WorldWideScience

Sample records for water disinfecting desinfection

  1. Emergency Disinfection of Drinking Water

    Science.gov (United States)

    How to boil and disinfect water to kill most disease-causing microorganisms during emergency situations where regular water service has been interrupted and local authorities recommend using only bottled water, boiled water, or disinfected water.

  2. [Disinfection for cistern water].

    Science.gov (United States)

    Ling, B; Han, G G; Shi, N; Shang, Q

    2001-03-01

    Rainwater is often collected into cisterns (pits or tanks) for household using as drinking water source in the rural areas of the northwest and the southeast coast in China, where no enough fresh water resource is available. However, the total number of bacteria and coliforms in the cisterns water was higher than the standard of that in drinking water. In order to ensure the safety for drinking, the effectiveness, conditions of treatment and cost for such disinfection methods compared with solar radiation, ultraviolet (UV), chloridation, micro-filteration and KDF were studied in 10 households in Cixi of Zhejiang Province and Weiyuan of Gansu Provinces, respectively. The micro-filteration is more compatible for bacteria removal in the tanks, while chloridation more for disinfection in the underground pits.

  3. Solar water disinfection

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R. [Universal Recycled Water Systems, Orlando, FL (United States); Collier, R. [Enerscope, Inc., Merritt Island, FL (United States)

    1996-11-01

    Non-potable drinking water is a major problem for much of the world`s population. It has been estimated that from 15 to 20 million children under the age of 5 die from diarrheal conditions brought on by infected drinking water every year. This is equivalent to a fully-loaded DC-10 crashing every ten minutes of every day, 365 days a year. Heat is one of the most effective methods of disinfecting drinking water. Using conventional means of heating water (heating on an open-flamed stove) results in an extremely energy-intensive process. The main obstacle is that for areas of the world where potable water is a problem, fuel supplies are either too expensive, not available, or the source of devastating environmental problems (deforestation). The apparatus described is a solar-powered water disinfection device that can overcome most if not all of the barriers that presently limit technological solutions to drinking water problems. It uses a parabolic trough solar concentrator with a receiver tube that is also a counterflow heat exchanger. The system is totally self-contained utilizing a photovoltaic-powered water pump, and a standard automotive thermostat for water flow control. The system is designed for simplicity, reliability and the incorporation of technology readily accessible in most areas of the world. Experiments at the Florida Solar Energy Center have demonstrated up to 2,500 liters of safe drinking water per day with 28 square meters of solar concentrator.

  4. Water disinfection agents and disinfection by-products

    Science.gov (United States)

    Ilavský, J.; Barloková, D.; Kapusta, O.; Kunštek, M.

    2017-10-01

    The aim of this work is to describe factors of water quality change in the distribution network and legislative requirements in Slovakia for disinfectants and disinfection byproducts (DBPs). In the experimental part, the time dependence of the application of the chlorine dioxide and sodium hypochlorite on the formation of some by-products of disinfection for drinking water from WTP Hriňová is studied. We monitored trihalomethanes, free chlorine, chlorine dioxide and chlorites.

  5. Alternative disinfectant water treatments

    Science.gov (United States)

    Alternative disinfestant water treatments are disinfestants not as commonly used by the horticultural industry. Chlorine products that produce hypochlorous acid are the main disinfestants used for treating irrigation water. Chlorine dioxide will be the primary disinfestant discussed as an alternativ...

  6. Silver disinfection in water distribution systems

    Science.gov (United States)

    Silvestry Rodriguez, Nadia

    Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems.

  7. Ultraviolet (UV) Disinfection for Drinking Water Systems

    Science.gov (United States)

    UV disinfection is an effective process for inactivating many microbial pathogens in water with potential to serve as stand-alone treatment or in combination with other disinfectants. USEPA provided guidance on the validation of UV reactors nearly a decade ago. Since then, lesson...

  8. Intracellular mechanisms of solar water disinfection

    Science.gov (United States)

    Castro-Alférez, María; Polo-López, María Inmaculada; Fernández-Ibáñez, Pilar

    2016-12-01

    Solar water disinfection (SODIS) is a zero-cost intervention measure to disinfect drinking water in areas of poor access to improved water sources, used by more than 6 million people in the world. The bactericidal action of solar radiation in water has been widely proven, nevertheless the causes for this remain still unclear. Scientific literature points out that generation of reactive oxygen species (ROS) inside microorganisms promoted by solar light absorption is the main reason. For the first time, this work reports on the experimental measurement of accumulated intracellular ROS in E. coli during solar irradiation. For this experimental achievement, a modified protocol based on the fluorescent probe dichlorodihydrofluorescein diacetate (DCFH-DA), widely used for oxidative stress in eukaryotic cells, has been tested and validated for E. coli. Our results demonstrate that ROS and their accumulated oxidative damages at intracellular level are key in solar water disinfection.

  9. Disinfection of water distribution systems for Legionella.

    Science.gov (United States)

    Lin, Y S; Stout, J E; Yu, V L; Vidic, R D

    1998-06-01

    Hospital-acquired legionnaires' disease arises from the presence of Legionella in hospital water systems. Legionella not only persists in hot water tanks but is also found in the biofilm throughout the entire water distribution system. Conditions within water systems that promote Legionella colonization include water temperature, configuration and age of the hot water tank, physicochemical constituents of the water, plumbing materials, and commensal microflora. Hospital-acquired legionnaires' disease has been prevented by instituting control measures directed at the water distribution system. These include superheat-and-flush, copper/silver ionization, ultraviolet light, instantaneous heating systems, and hyperchlorination. Each of the above disinfection methods has been proven to be effective in the short-term, but long-term efficacy has been difficult due to limitations associated with each method. The complexities of Legionella disinfection, including advantages and disadvantages of each method, are reviewed. A successful Legionella prevention program requires cooperation and communication among hospital administrative personnel, engineers, and infection control staff. Routine environmental surveillance cultures for Legionella are the critical component for successful long-term disinfection. Culture results document the efficacy of the disinfection method and alert the hospital staff to consider Legionella in hospitalized patients with pneumonia.

  10. development of an automated batch-process solar water disinfection

    African Journals Online (AJOL)

    user

    (Joules) preset at the beginning of the experiment/disinfection process. Fig. 2: Schematic diagram of the automated batch- process solar water disinfection system. Fig. 3: Pictorial view of the automated batch-process solar water disinfection system. Figure 4: Circuitry of Arduino® microcontroller with the different sensors ...

  11. Biological Treatment of Water Disinfection Byproducts using ...

    Science.gov (United States)

    Major disinfection by-products (DBPs) from the chlorination process of drinking water include trihalomethanes (THMs) and haloacetic acides (HAA5). THMs mainly consist of chloroform, and other harsh chemicals. Prolonged consumptions of drinking water containing high levels of THMs has been linked with diseases of the liver, kidneys, bladder, or central nervous system and may increase likelihood of cancer. A risk also exists for THMs exposure via inhalation while showering, bathing or washing clothes and dishes. Due to these risks, the U.S. EPA regulate THMs content in drinking water. This research investigates biological degradation of THM using chloroform as a model compound. The study aims to decrease possible risks of THMs through filtration. Throughout this year’s presentations, there is a common theme of health and safety concerns. UC researchers are working hard to clean water ways of naturally occurring contaminates as well as man-made toxins found in our waterways. The significance of these presentations translates into the promise of safer environments, and more importantly saved lives, as UC’s faculty continues to produce real-world solutions to problems threatening the world around us. A biotech process has been developed and demonstrated that effectively remove and treat volatile disinfection by-products from drinking water. The process strips low concentration disinfection by-products, such as trihalomethanes, that are formed during the chlori

  12. Carbon nanoparticles for solar disinfection of water.

    Science.gov (United States)

    Maddigpu, Pratap Reddy; Sawant, Bhairavi; Wanjari, Snehal; Goel, M D; Vione, Davide; Dhodapkar, Rita S; Rayalu, S

    2018-02-05

    The present manuscript deals with the application of carbon nano particles (CNP) and chitosan (CHIT) in the form of CHIT-CNP composite for the disinfection of water. The CHIT-CNP composite was prepared by the solution casting method and characterized by TEM, XRD and elemental analysis. In the present investigation we study the disinfection efficiency towards E. coli bacteria of both CNP and CHIT-CNP, under sunlight (SODIS) in identical experimental conditions. Both CNP and CHIT-CNP enhanced disinfection as compared to SODIS alone, and comparable performance was achieved when the same dose of CNP in the two materials was applied. However, the CHIT-CNP composite is in the form of a fabric and it is easier to use and handle as compared to the CNP powder, especially in rural and resource-constrained areas. Moreover the SODIS-CHIT-CNP setup, when used in a compound parabolic collector (CPC) reactor showed high bactericidal efficiency compared to SODIS alone, which is promising for practical applications. The disinfection potential of the CNP powder was compared with that of the well-known material TiO 2 Degussa P25 (DP 25 ): DP 25 gave 6-log kill of bacteria in 180min, whereas CNP produced 6-log kill in 150min. Copyright © 2017. Published by Elsevier B.V.

  13. MODELING DISINFECTANT RESIDUALS IN DRINKING-WATER STORAGE TANKS

    Science.gov (United States)

    The factors leading to the loss of disinfectant residual in well-mixed drinking-water storage tanks are studied. Equations relating disinfectant residual to the disinfectant's reation rate, the tank volume, and the fill and drain rates are presented. An analytical solution for ...

  14. [Disinfection efficiency for outlet water from biological activated carbon process by different disinfecting modes].

    Science.gov (United States)

    Zhi, Xing-hua; Bai, Xiao-hui; Meng, Ming-qun

    2011-05-01

    Lab-scale tests were designed to treat the leak of bacteria from BAC process. Water samples from outlet of BAC pool in Xujing Waterworks in Shanghai were disinfected by NaClO and NH2Cl disinfectant to compare the disinfection efficiency. Heterotrophic bacteria in disinfected water were cultivated and counted and halo hydrocarbons were detected by GC. To keep the disinfecting efficacy [lg(N0/N)] over 2 under the water temperature of 30 degrees C, NaClO should have an initial concentration more than 1.84 mg/L total chlorine and contact with bacteria for about 30 minutes. As to NH2Cl disinfection, the initial concentration should be more than 2.20 mg/L total chlorine and contacting time should be prolonged to about 90 minutes. The production of CHCl3 ranged from 4.97 to 7.10 microg/L and CCl4 ranged from 0.01 to 0.71 microg/L in NaClO disinfection tests with a initial disinfecting concentration in the range of 1.53-2.42 mg/L total chlorine values. In NH2Cl disinfecting tests, CHCl3 ranged from 4.43 to 5.55 microg/L and CCl4 ranged from 0.01 to 0.64 microg/L when initial disinfecting concentration limited in the range of 2.10-2.86 mg/L total chlorine values. All was below the state drinking water standard. The results showed that the disinfection process can be divided into fast step and slow step. NaCl0 has higher disinfecting efficiency on bacteria than NH2Cl, but neither can reach 100% effectivity. Meanwhile the risk of producing halo hydrocarbon over standard was proved to be negligible.

  15. Spiral-shaped reactor for water disinfection

    KAUST Repository

    Soukane, Sofiane

    2016-04-20

    Chlorine-based processes are still widely used for water disinfection. The disinfection process for municipal water consumption is usually carried out in large tanks, specifically designed to verify several hydraulic and disinfection criteria. The hydrodynamic behavior of contact tanks of different shapes, each with an approximate total volume of 50,000 m3, was analyzed by solving turbulent momentum transport equations with a computational fluid dynamics code, namely ANSYS fluent. Numerical experiments of a tracer pulse were performed for each design to generate flow through curves and investigate species residence time distribution for different inlet flow rates, ranging from 3 to 12 m3 s−1. A new nature-inspired Conch tank design whose shape follows an Archimedean spiral was then developed. The spiral design is shown to strongly outperform the other tanks’ designs for all the selected plug flow criteria with an enhancement in efficiency, less short circuiting, and an order of magnitude improvement in mixing and dispersion. Moreover, following the intensification philosophy, after 50% reduction in its size, the new design retains its properties and still gives far better results than the classical shapes.

  16. Disinfection of contaminated water by using solar irradiation.

    Science.gov (United States)

    Caslake, Laurie F; Connolly, Daniel J; Menon, Vilas; Duncanson, Catriona M; Rojas, Ricardo; Tavakoli, Javad

    2004-02-01

    Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min.

  17. Antimicrobial-Coated Granules for Disinfecting Water

    Science.gov (United States)

    Akse, James R.; Holtsnider, John T.; Kliestik, Helen

    2011-01-01

    Methods of preparing antimicrobialcoated granules for disinfecting flowing potable water have been developed. Like the methods reported in the immediately preceding article, these methods involve chemical preparation of substrate surfaces (in this case, the surfaces of granules) to enable attachment of antimicrobial molecules to the surfaces via covalent bonds. A variety of granular materials have been coated with a variety of antimicrobial agents that include antibiotics, bacteriocins, enzymes, bactericides, and fungicides. When employed in packed beds in flowing water, these antimicrobial-coated granules have been proven effective against gram-positive bacteria, gram-negative bacteria, fungi, and viruses. Composite beds, consisting of multiple layers containing different granular antimicrobial media, have proven particularly effective against a broad spectrum of microorganisms. These media have also proven effective in enhancing or potentiating the biocidal effects of in-line iodinated resins and of very low levels of dissolved elemental iodine.

  18. Recent advances in drinking water disinfection: successes and challenges.

    Science.gov (United States)

    Ngwenya, Nonhlanhla; Ncube, Esper J; Parsons, James

    2013-01-01

    Drinking water is the most important single source of human exposure to gastroenteric diseases, mainly as a result of the ingestion of microbial contaminated water. Waterborne microbial agents that pose a health risk to humans include enteropathogenic bacteria, viruses, and protozoa. Therefore, properly assessing whether these hazardous agents enter drinking water supplies, and if they do, whether they are disinfected adequately, are undoubtedly aspects critical to protecting public health. As new pathogens emerge, monitoring for relevant indicator microorganisms (e.g., process microbial indicators, fecal indicators, and index and model organisms) is crucial to ensuring drinking water safety. Another crucially important step to maintaining public health is implementing Water Safety Plans (WSPs), as is recommended by the current WHO Guidelines for Drinking Water Quality. Good WSPs include creating health-based targets that aim to reduce microbial risks and adverse health effects to which a population is exposed through drinking water. The use of disinfectants to inactivate microbial pathogens in drinking water has played a central role in reducing the incidence of waterborne diseases and is considered to be among the most successful interventions for preserving and promoting public health. Chlorine-based disinfectants are the most commonly used disinfectants and are cheap and easy to use. Free chlorine is an effective disinfectant for bacteria and viruses; however, it is not always effective against C. parvum and G. lamblia. Another limitation of using chlorination is that it produces disinfection by-products (DBPs), which pose potential health risks of their own. Currently, most drinking water regulations aggressively address DBP problems in public water distribution systems. The DBPs of most concern include the trihalomethanes (THMs), the haloacetic acids (HAAs), bromate, and chlorite. However, in the latest edition of the WHO Guidelines for Drinking Water Quality

  19. Sewage disinfection towards protection of drinking water resources.

    Science.gov (United States)

    Kolch, A

    2000-01-01

    Wastewater applied in agriculture for irrigation could replace the use of natural drinking-water resources. With respect to high concentrations of human pathogens wastewater has to be disinfected prior to use. This paper introduces disinfection methods with emphasis on UV irradiation.

  20. Waterline ATS B. globigii spore water disinfection data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Disinfection of B. globigii spores (a non-pathogenic surrogate for B. anthracis) in clean and dirty water using the ATS-Waterline system, which uses ultraviolet...

  1. A review of heterogeneous photocatalysis for water and surface disinfection.

    Science.gov (United States)

    Byrne, John Anthony; Dunlop, Patrick Stuart Morris; Hamilton, Jeremy William John; Fernández-Ibáñez, Pilar; Polo-López, Inmaculada; Sharma, Preetam Kumar; Vennard, Ashlene Sarah Margaret

    2015-03-30

    Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give "self-disinfecting" surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes.

  2. A Review of Heterogeneous Photocatalysis for Water and Surface Disinfection

    Directory of Open Access Journals (Sweden)

    John Anthony Byrne

    2015-03-01

    Full Text Available Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give “self-disinfecting” surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes.

  3. Stability and effectiveness of chlorine disinfectants in water distribution systems.

    Science.gov (United States)

    Olivieri, V P; Snead, M C; Krusé, C W; Kawata, K

    1986-11-01

    A test system for water distribution was used to evaluate the stability and effectiveness of three residual disinfectants--free chlorine, combined chlorine, and chlorine dioxide--when challenged with a sewage contaminant. The test distribution system consisted of the street main and internal plumbing for two barracks at Fort George G. Meade, MD. To the existing pipe network, 152 m (500 ft) of 13-mm (0.5 in.) copper pipe were added for sampling, and 60 m (200 ft) of 2.54-cm (1.0 in.) plastic pipe were added for circulation. The levels of residual disinfectants tested were 0.2 mg/L and 1.0 mg/L as available chlorine. In the absence of a disinfectant residual, microorganisms in the sewage contaminant were consistently recovered at high levels. The presence of any disinfectant residual reduced the microorganism level and frequency of occurrence at the consumer's tap. Free chlorine was the most effective residual disinfectant and may serve as a marker or flag in the distribution network. Free chlorine and chlorine dioxide were the least stable in the pipe network. The loss of disinfectant in the pipe network followed first-order kinetics. The half-life determined in static tests for free chlorine, chlorine dioxide, and combined chlorine was 140, 93, and 1680 min.

  4. Effect of point‐of‐use disinfection, flocculation and combined flocculation–disinfection on drinking water quality in western Kenya

    National Research Council Canada - National Science Library

    Crump, J.A; Okoth, G.O; Slutsker, L; Ogaja, D.O; Keswick, B.H; Luby, S.P

    2004-01-01

    .... Methods and Results:  We evaluated a novel combined flocculant‐disinfectant point‐of‐use water treatment product and compared its effect on drinking water quality with existing technologies in western Kenya...

  5. Development of an Ultrasonic Resonator for Ballast Water Disinfection

    Science.gov (United States)

    Osman, Hafiiz; Lim, Fannon; Lucas, Margaret; Balasubramaniam, Prakash

    Ultrasonic disinfection involves the application of low-frequency acoustic energy in a water body to induce cavitation. The implosion of cavitation bubbles generates high speed microjets >1 km/s, intense shock wave >1 GPa, localized hot spots >1000 K, and free-radicals, resulting in cell rupture and death of micro-organisms and pathogens. Treatment of marine ballast water using power ultrasonics is an energy-intensive process. Compared with other physical treatment methods such as ultraviolet disinfection, ultrasonic disinfection require 2 to 3 orders of magnitude more energy to achieve similar rate of micro-organism mortality. Current technology limits the amount of acoustic energy that can be transferred per unit volume of fluid and presents challenges when it comes to high-flow applications. Significant advancements in ultrasonic processing technology are needed before ultrasound can be recognized as a viable alternative disinfection method. The ultrasonic resonator has been identified as one of the areas of improvement that can potentially contribute to the overall performance of an ultrasonic disinfection system. The present study focuses on the design of multiple-orifice resonators (MOR) for generating a well-distributed cavitation field. Results show that the MOR resonator offers significantly larger vibrational surface area to mass ratio. In addition, acoustic pressure measurements indicate that the MOR resonators are able to distribute the acoustic energy across a larger surface area, while generating 2-4 times higher pressures than existing ultrasonic probes.

  6. A novel fiber optical device for ultraviolet disinfection of water.

    Science.gov (United States)

    Lu, Gang; Li, Chaolin; Zheng, Yinggang; Zhang, Qian; Peng, Juan; Fu, Ming

    2008-07-24

    Since there are several problems in traditional UV disinfection techniques, a highly efficient, reliable and economical method, using quartz optical fibers to deliver UV light is proposed. The principle of the experimental setup is that ultraviolet rays are gathered by a reflector and converge on a light point, the diameter of approximately 5mm. In this way UV light can be transferred into water to kill the bacteria in the water. This paper presents preliminary results on water disinfection using this new UV disinfection setup. Its suitability for application could be shown in experiments with E. coli (ATCC8099) as test microorganisms. We have optimized the distribution of the optical fibers in the water in bench-scale study. This result can provide guidance for pilot-scale and field-scale study of this new technique. The results show that the new technique had a good performance under different conditions as follows: (a) turbidity level=10.2 NTU, (b) ferric ion concentration=0.3 mg/L, and (c) humic acid concentration=5 mg/L. The new technique provides a promising approach to disinfection treatment of drinking water.

  7. Survival of Viral Biowarfare Agents in Disinfected Waters

    Directory of Open Access Journals (Sweden)

    Mary Margaret Wade

    2010-01-01

    Full Text Available Protecting civilian and military water supplies has received more attention since the United States began its war on terror in 2001. Both chlorine and bromine are used by branches of the U.S. military for disinfecting water supplies; however, limited data exists as to the effectiveness of these additives when used against viral biowarfare agents. The present study sought to evaluate the survival of selected viral biothreat agents in disinfected water. Disinfected water samples were spiked with vaccinia virus strain WR and Venezuelan equine encephalitis (VEE virus strain TC-83 each separately to a final concentration of approximately 1×106 PFU/mL, and survival was assessed by plaque assay. Both viruses were inactivated by 1 mg/L free available chlorine (FAC and 2mg/L total bromine within one hour. In conclusion, these results demonstrate that both chlorine and bromine are effective disinfectants against vaccinia virus and VEE strain TC-83 at the concentrations tested.

  8. Photocatalytic Enhancement for Solar Disinfection of Water: A Review

    Directory of Open Access Journals (Sweden)

    J. Anthony Byrne

    2011-01-01

    Full Text Available It is estimated that 884 million people lack access to improved water supplies. Many more are forced to rely on supplies that are microbiologically unsafe, resulting in a higher risk of waterborne diseases, including typhoid, hepatitis, polio, and cholera. Due to poor sanitation and lack of clean drinking water, there are around 4 billion cases of diarrhea each year resulting in 2.2 million deaths, most of these are children under five. While conventional interventions to improve water supplies are effective, there is increasing interest in household-based interventions to produce safe drinking water at an affordable cost for developing regions. Solar disinfection (SODIS is a simple and low cost technique used to disinfect drinking water, where water is placed in transparent containers and exposed to sunlight for 6 hours. There are a number of parameters which affect the efficacy of SODIS, including the solar irradiance, the quality of the water, and the nature of the contamination. One approach to SODIS enhancement is the use of semiconductor photocatalysis to produce highly reactive species that can destroy organic pollutants and inactivate water pathogens. This paper presents a critical review concerning semiconductor photocatalysis as a potential enhancement technology for solar disinfection of water.

  9. Subacute toxicity assessment of water disinfection byproducts on zebrafish.

    Science.gov (United States)

    Rácz, Gergely; Csenki, Zsolt; Kovács, Róbert; Hegyi, Arpád; Baska, Ferenc; Sujbert, László; Zsákovics, Ivett; Kis, Renáta; Gustafson, Ryan; Urbányi, Béla; Szende, Béla

    2012-07-01

    Disinfection of raw water is essential to the production of drinking water. However, by-products of disinfection may exert toxic effects. The potential toxic effects of two of these compounds, 4-ethylbenzaldehyde (EBA) and 2,4-difluoroaniline (DFA) were investigated using the zebrafish (Danio rerio) model. The two compounds, dissolved, were introduced in duplicate aquariums containing zebrafish in two different concentrations based on LC50 values. The aquarium water containing EBA or DFA was changed every 96 h throughout the 3 months of treatment. Behavior of the fish in each replicate was inspected twice daily. In course of treatment with both concentrations, fish exposed to DFA displayed behavior associated with visible anxiety, while EBA treated were lethargic and did not evade capture. Application of both concentrations of each component into the aquarium water resulted in dystrophic lesions in the liver, kidney and skin of the fish while preneoplastic lesions and tumors were not observed.

  10. QUENCHING OF CHLORINATION DISINFECTION BY-PRODUCT FORMATION IN DRINKING WATER BY HYDROGEN PEROXIDE. (R825362)

    Science.gov (United States)

    Reactions between chlorine disinfectants, dissolved organic matter, and other chemicals in water form a series of disinfection by-products (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs), that are toxic and subject to increasingly stringent regulations. Th...

  11. [Genotoxicity of drinking water during chlorine and chloramine disinfection and the influence of disinfection conditions using the umu-test].

    Science.gov (United States)

    Liu, Qing; Zhang, Li-Ping; Liu, Wen-Jun; Nie, Xue-Biao; Zhang, Su-Xia; Zhang, Shun

    2010-01-01

    In this study, the effects of disinfectant dosage, reaction time and the ratio of Cl2 to N of disinfectant on genotoxicity of effluent of ozone-biological activated carbon (O3-BAC) during chlorine or chloramine disinfection were investigated using umu-test. It was found that, the genotoxicity of effluent of O3-BAC before disinfection ranged from 20-70 ng/L, and it increased after disinfection by chlorine or chloramines. With the same reaction time(24 h), genotoxicity after chlorination (40-95 ng/L) was higher than that after chloramination (20-40 ng/L) under same initial dosage. For chlorination, with initial dosage increasing from 0 mg/L to 10 mg/L, genotoxicity increased firstly, and got the maximum value at about 0.5-1 mg/L dosage, then decreased and got the minimum value at about 3-5 mg/L dosage, and finally increased again. For chloramination, genotoxicity didn't change that much. With the dosage of 3 mg/L and reaction time increasing from 0 h to 72 h, no matter for chlorine or chloramines disinfection, genotoxicity of effluent of O3-BAC both increased firstly, and got the maximum value at about 2 h, then decreased and got the minimum value at about 18 h, and finally increased again, and genotoxicity after chlorine disinfection (83-120 ng/L) was higher than that after chloramines disinfection (20-62 ng/L) under same reaction time. Further more, effects of the different ratios of Cl2 to N of disinfectant on genotoxicity of effluent of O3-BAC were also studied. Results of this study demonstrate that under test conditions, chloramine disinfection is safer than chlorine disinfection in the aspect of genotoxicity for drinking water, and the changes of genotoxicity are different from those of total HAAs.

  12. Infectious Disinfection: "Exploring Global Water Quality"

    Science.gov (United States)

    Mahaya, Evans; Tippins, Deborah J.; Mueller, Michael P.; Thomson, Norman

    2009-01-01

    Learning about the water situation in other regions of the world and the devastating effects of floods on drinking water helps students study science while learning about global water quality. This article provides science activities focused on developing cultural awareness and understanding how local water resources are integrally linked to the…

  13. Chlorine dioxine DBPs (disinfection by-products in drinking water

    Directory of Open Access Journals (Sweden)

    C. Lasagna

    2013-01-01

    Full Text Available Since the 1970s it has been well known that, though water for human consumption is generally disinfected before being distributed along the network, the use of chemicals results in the formation of many different Disinfection By-Products (DBPs. In the case of chlorine dioxide, the most important and represented DBPs are chlorite and chlorate: after an introduction concerning the current Italian regulation on this subject, in the experimental part the results of a 7-year minitoring campaign, concerning water of different origin collected from taps in various Italian regions, are shown. The analytical technique used for the determination of chlorite and chlorate was Ion Chromatography. The result obtained are finally discussed.

  14. Solar disinfection of drinking water and oral rehydration solutions

    Energy Technology Data Exchange (ETDEWEB)

    Acra, A.; Raffoul, Z.; Karahagopian, Y.

    1984-01-01

    This document provides concise information on oral rehydration therapy for the control of diarrheal diseases in developing countries; however, the main emphasis has been placed on the disinfection of oral rehydration solutions, or the water used in their preparation, as achieved by exposure to sunlight in transparent containers. The fundamental principles of solar energy are presented as well as studies which demonstrate the efficacy of the method. 2 figures, 6 tables.

  15. Conventional and Alternative Disinfection Methods of Legionella in Water Distribution Systems – Review

    Directory of Open Access Journals (Sweden)

    Pūle Daina

    2016-12-01

    Full Text Available Prevalence of Legionella in drinking water distribution systems is a widespread problem. Outbreaks of Legionella caused diseases occur despite various disinfectants are used in order to control Legionella. Conventional methods like thermal disinfection, silver/copper ionization, ultraviolet irradiation or chlorine-based disinfection have not been effective in the long term for control of biofilm bacteria. Therefore, research to develop more effective disinfection methods is still necessary.

  16. The effect of disinfectant solutions on the hardness of acrylic resin denture teeth.

    Science.gov (United States)

    Pavarina, A C; Vergani, C E; Machado, A L; Giampaolo, E T; Teraoka, M T

    2003-07-01

    This investigation studied the effects of disinfectant solutions on the hardness of acrylic resin denture teeth. The occlusal surfaces of 64 resin denture teeth were ground flat with abrasives up to 400-grit silicon carbide paper. Measurements were made after polishing and after the specimens were stored in water at 37 degrees C for 48 h. The specimens were then divided into four groups and immersed in chemical disinfectants (4% chlorhexidine; 1% sodium hypochlorite and sodium perborate) for 10 min. The disinfection methods were performed twice to simulate clinical conditions and hardness measurements were made. Specimens tested as controls were immersed in water during the same disinfection time. Eight specimens were produced for each group. After desinfection procedures, testing of hardness was also performed after the samples were stored at 37 degrees C for 7, 30, 60, 90 and 120 days. Data were analysed using two-way analysis of variance (anova) and Tukey's test at 95% confidence level. According to the results, no significant differences were found between materials and immersion solutions (P > 0.05). However, a continuous decrease in hardness was noticed after ageing (P acrylic resin denture teeth softened upon immersion in water regardless the disinfecting solution.

  17. Vortex Stabilized Plasma for Rapid Water Disinfection & Pharmaceutical Degradation

    Science.gov (United States)

    Hershcovitch, Ady

    2016-10-01

    Good quality drinking water is dwindling for large segments of the world population. Aggravating the problem is proliferation of antibiotics in the water supply, which give rise to drug resistant pathogens. One option for water supply increase is recycling waste and polluted water by inexpensive, environmentally friendly methods. Presently disinfection uses chemicals and UV radiation. Chemicals are limited by residual toxicity, while UV consumes much electricity. Current methods can remove only certain classes of drugs due to their large variety of physical and chemical properties. Plasmas in water are very attractive for degrading all pharmaceuticals and deactivating pathogens: intense arc current can physically break up any molecular bonds. UV radiation, ozone, etc. generation inside the water volume disinfects. Present utilized plasmas: glow, pulsed arcs are not power efficient; vortex stabilized plasmas are power efficient that can advance water treatment state-of-the-art by orders of magnitude. Proposed techniquefeatures novel components facilitating large diameter vortex stabilized in-water arcs with optimized plasma parameters for maximal UV-C emission; and harvests hydrogen centered by the vortex.

  18. Photocatalytic disinfection of water using low cost compound parabolic collectors

    Energy Technology Data Exchange (ETDEWEB)

    McLoughlin, O.A.; Gill, L.W. [Dublin Univ. (Ireland). Dept. of Civil, Structural and Environmental Engineering; Ibanez, F.; Gernjak, W.; Malato Rodriguez, S. [Plataforma Solar de Almeria (CIEMAT), Tabemas (Spain)

    2004-11-01

    The objective of this work was to assess the effectiveness of using near UV light to disinfect water supplies for potential applications in developing countries. A pilot scale photoreactor comprised of non-tracking compound parabolic collectors installed at Plataforma Solar de Almeria was examined and a comparison of disinfection efficiency using E. coli K-12 was carried out with a reactor configuration of 3 and 1 m{sup 2} illuminated area. Tests were also carried out using suspensions of titanium dioxide (TiO{sub 2}) at concentrations ranging from 0 to 9 mg/l. The removal of E. coli K-12 from initial concentrations of 1 x 10{sup 5} CFU/ml to below the limit of detection was achieved both with and without the use of TiO{sub 2}. Levels of inactivation in 35 l of inoculated water of up to 4-log removal were achieved in under 30 min. The addition of TiO{sub 2} created an enhancement to the process only at the 3 mg/l dose. However, the results have also suggested the possibility that another disinfection mechanism, possibly governed by the frequency of intermittent UV light exposure, was regulating the overall inactivation kinetics of the trials. (Author)

  19. Controlling Legionella in hospital drinking water: an evidence-based review of disinfection methods.

    Science.gov (United States)

    Lin, Yusen E; Stout, Janet E; Yu, Victor L

    2011-02-01

    Hospital-acquired Legionnaires' disease is directly linked to the presence of Legionella in hospital drinking water. Disinfecting the drinking water system is an effective preventive measure. The efficacy of any disinfection measures should be validated in a stepwise fashion from laboratory assessment to a controlled multiple-hospital evaluation over a prolonged period of time. In this review, we evaluate systemic disinfection methods (copper-silver ionization, chlorine dioxide, monochloramine, ultraviolet light, and hyperchlorination), a focal disinfection method (point-of-use filtration), and short-term disinfection methods in outbreak situations (superheat-and-flush with or without hyperchlorination). The infection control practitioner should take the lead in selection of the disinfection system and the vendor. Formal appraisals by other hospitals with experience of the system under consideration is indicated. Routine performance of surveillance cultures of drinking water to detect Legionella and monitoring of disinfectant concentrations are necessary to ensure long-term efficacy.

  20. EFFICACY OF NOVEL WATER DISINFECTION TECHNIQUES IN HORTICULTURAL NUTRIENT RECYCLING.

    Science.gov (United States)

    Heungens, K; Clierinck, M; Inghelbrecht, S; Vissers, M

    2015-01-01

    Hydroponic systems used for growing potted ornamentals in greenhouses are commonly ebb-and-flow irrigation systems. The drainage water is usually recycled to save water and nutrients. To avoid the spread of pathogens in these closed irrigation systems, disinfection of the recycled water is standard practice. Growers can use slow sand filtration or UV-radiation techniques, but these methods are often either not sulted for specific problems or they require an excessively large investment. The objective of this study was to test less expensive but effective alternative disinfection systems. The efficacy of five disinfection systems against fungi and oomycetes was determined: Aqua-Hort (based on Cu-ions), Reciclean (performic acid), D1-OX Forte (CIO2), ECA (electrochemically activated water = anodic oxidation: hypochlorite and free radicals) and Newtec (also anodic oxidation). These five systems and a no-sterilization control were integrated in small closed ebb-and-flow circuits with nutrient solution reservoirs of 400 L each. Activity against Fusarium was excellent with ECA, good with Newtec and DI-OX Forte, moderate with high doses of Reciclean (250 ppm H2O2 and poor with the Aqua-Hort. There was no Pythium in the ECA and Newtec systems, while still so in the Aqua-Hort system, even at high doses (up to 7 ppm Cu++). Although the Reciclean (up to 100 ppm H2O2) and Aqua-Hort systems did not perform well against the pathogens, they did very well against algae; especially Reciclean was also useful against duckweed in water and liverwort on soil substrates. Concentrations of total Cl were elevated in water, substrate and plants after treatments with ECA and Newtec; other accumulations were Cu (Aqua-Hort), Na and SO4 (DI-OX Forte). However, only on a limited number of plant species these accumulations produced phytotoxic effects.

  1. ANALYZING DRINKING WATER FOR DISINFECTION BYPRODUCTS

    Science.gov (United States)

    In the mid 19th Century, Chinese workers on the North American transcontinental railroad suffered less illness than other groups. While generally mysterious at the time, today the reason is obvious. The Chinese preference for tea required heating the water, thus killing many path...

  2. Toxic impact of bromide and iodide on drinking water disinfected with chlorine or chloramines.

    Science.gov (United States)

    Yang, Yang; Komaki, Yukako; Kimura, Susana Y; Hu, Hong-Ying; Wagner, Elizabeth D; Mariñas, Benito J; Plewa, Michael J

    2014-10-21

    Disinfectants inactivate pathogens in source water; however, they also react with organic matter and bromide/iodide to form disinfection byproducts (DBPs). Although only a few DBP classes have been systematically analyzed for toxicity, iodinated and brominated DBPs tend to be the most toxic. The objectives of this research were (1) to determine if monochloramine (NH2Cl) disinfection generated drinking water with less toxicity than water disinfected with free chlorine (HOCl) and (2) to determine the impact of added bromide and iodide in conjunction with HOCl or NH2Cl disinfection on mammalian cell cytotoxicity and genomic DNA damage induction. Water disinfected with chlorine was less cytotoxic but more genotoxic than water disinfected with chloramine. For both disinfectants, the addition of Br(-) and I(-) increased cytotoxicity and genotoxicity with a greater response observed with NH2Cl disinfection. Both cytotoxicity and genotoxicity were highly correlated with TOBr and TOI. However, toxicity was weakly and inversely correlated with TOCl. Thus, the forcing agents for cytotoxicity and genotoxicity were the generation of brominated and iodinated DBPs rather than the formation of chlorinated DBPs. Disinfection practices need careful consideration especially when using source waters containing elevated bromide and iodide.

  3. [First results on the use of chloramines to reduce disinfection byproducts in drinking water].

    Science.gov (United States)

    Azara, Antonio; Muresu, Elena; Dettori, Marco; Ciappeddu, Pierluigi; Deidda, Antonio; Maida, Alessandro

    2010-01-01

    The presence of disinfection byproducts (DBP) in drinking water raises concerns about the safety of chlorination and is one of the problems inherent the use of surface water as a source of drinking water. In order to reduce the presence of DBP (in particular of chlorites), we evaluated the combined use of chlorine dioxide for primary disinfection and monochloramine for residual disinfection in a water purification plant and distribution system in Sardinia (Italy). The results are very encouraging. Disinfection byproducts were reduced and other parameters were found to be within the recommended standards, indicating further improvements of the purification process.

  4. Decontamination of B. globigii spores from drinking water infrastructure using disinfectants

    Data.gov (United States)

    U.S. Environmental Protection Agency — Decontamination of Bacillus spores adhered to common drinking water infrastructure surfaces was evaluated using a variety of disinfectants. Corroded iron and...

  5. Formation of organic chloramines during water disinfection: chlorination versus chloramination.

    Science.gov (United States)

    Lee, Wontae; Westerhoff, Paul

    2009-05-01

    Many of the available studies on formation of organic chloramines during chlorination or chloramination have involved model organic nitrogen compounds (e.g., amino acids), but not naturally occurring organic nitrogen in water. This study assessed organic chloramine formation during chlorination and chloramination of 16 natural organic matter (NOM) solutions and 16 surface waters which contained dissolved organic nitrogen (DON). Chlorination rapidly formed organic chloramines within 10 min, whereas chloramination formed organic chloramination much more slowly, reaching the maximum concentration between 2 and 120 h after the addition of monochloramine into the solutions containing DON. The average organic chloramine formation upon addition of free chlorine and monochloramine into the NOM solutions were 0.78 mg-Cl(2)/mg-DON at 10 min and 0.16 mg-Cl(2)/mg-DON at 24h, respectively. Organic chloramine formation upon chlorination and chloramination increased as the dissolved organic carbon/dissolved organic nitrogen (DOC/DON) ratio decreased (i.e., DON contents increased). Chlorination of molecular weight (10,000 Da) fractionated water showed that molecular weight of DON would not impact the amount of organic chloramines produced. Comparison of three different disinfection schemes at water treatment plants (free chlorine, preformed monochloramine, and chlorine/ammonia additions) indicated organic chloramine formation could lead to a possible overestimation of disinfection capacity in many chloraminated water systems that add chlorine followed by an ammonia addition to form monochloramine.

  6. Formulation of a mathematical model to predict solar water disinfection.

    Science.gov (United States)

    Salih, Fadhil M

    2003-09-01

    A mathematical model was formulated that will facilitate the prediction of solar disinfection by analyzing the effect of sunlight exposure (x(1)) and the load of bacterial contamination (x(2)), as predictor variables, on the efficiency of solar disinfection (y). Aliquots of 0.1 ml containing average numbers of E. coli, ranging between 1 and 5 x 10(3)cells/ml raw water, were introduced into each of the 96 wells of polystyrene microtitre plates. Plates, with the lid on, were exposed to sunlight for varying exposures ranging between 1.04 x 10(3) and 8.40 x 10(3)kJ m(-2). Double strength nutrient broth was then added. After 48 h incubation wells containing visible contamination were considered as containing one cell or more that survived the exposure. Data showed that disinfection is dependent both on the load of bacterial contamination and sunlight exposure. This relationship is characterized by curves having shoulders followed by a steep decline and then tailing off in an asymptotic fashion. The shoulder size increased with the increase of the contamination load, however, the slope remains the same. Statistical analysis indicates a positive correlation among the variables (R(2) = 0.893); the mathematical model, y=1-(1-e(-kx(1)))(x(2)), represents the relationship, with k being the solar inactivation constant. The exposure required to produce a given decontamination level can be predicted using the equation: x(1)=-1/kln[1-(1-y)(-1/x(2))]e(-micro/rho.m/A), where micro is the linear attenuation coefficient (m(-1)), rho is the density, m is the mass and A is the area of the exposed part of the sample. The predictor variables (x(1), x(2)) strongly influence the efficiency of solar disinfection, which can be predicted using the suggested mathematical model. The present data provides a means to predict the efficiency of solar disinfection as an approach to improve the quality of drinking water mainly in developing countries with adequate sunshine all year-round.

  7. An overview of water disinfection in developing countries and the potential for solar thermal water pasteurization

    Energy Technology Data Exchange (ETDEWEB)

    Burch, J.; Thomas, K.E.

    1998-01-01

    This study originated within the Solar Buildings Program at the U.S. Department of Energy. Its goal is to assess the potential for solar thermal water disinfection in developing countries. In order to assess solar thermal potential, the alternatives must be clearly understood and compared. The objectives of the study are to: (a) characterize the developing world disinfection needs and market; (b) identify competing technologies, both traditional and emerging; (c) analyze and characterize solar thermal pasteurization; (d) compare technologies on cost-effectiveness and appropriateness; and (e) identify research opportunities. Natural consequences of the study beyond these objectives include a broad knowledge of water disinfection problems and technologies, introduction of solar thermal pasteurization technologies to a broad audience, and general identification of disinfection opportunities for renewable technologies.

  8. The effect of disinfectant agents in eliminating the contamination of dental unit water

    NARCIS (Netherlands)

    Ozcan, M; Kulak, Y; Kazazoglu, E

    High concentrations of water-borne organisms cause multiple public health problems. Contamination of water exiting the dental unit water lines could be inhibited with the use of some disinfectants. The purpose of this investigation was to establish the effect of two disinfectants and to test their

  9. The Recreational Water Cycle: From Source Water to Tap Water to Spa and Swimming Pool Water: Effects of Disinfectants and Precursors and Implications for Exposure and Toxicity

    Science.gov (United States)

    The current study investigates the effect of different disinfection treatments on the disinfection by-products (DBPs) formed in finished drinking water vs. tap water vs. swimming pool water vs. spa waters. To this end, complete water pathway samples (untreated source waters ->fi...

  10. Stability and effectiveness of chlorine disinfectants in water distribution systems.

    OpenAIRE

    Olivieri, V P; Snead, M C; Krusé, C W; Kawata, K

    1986-01-01

    A test system for water distribution was used to evaluate the stability and effectiveness of three residual disinfectants--free chlorine, combined chlorine, and chlorine dioxide--when challenged with a sewage contaminant. The test distribution system consisted of the street main and internal plumbing for two barracks at Fort George G. Meade, MD. To the existing pipe network, 152 m (500 ft) of 13-mm (0.5 in.) copper pipe were added for sampling, and 60 m (200 ft) of 2.54-cm (1.0 in.) plastic p...

  11. Field-testing UV disinfection of drinking water

    Energy Technology Data Exchange (ETDEWEB)

    Gadgil, A.; Drescher, A.; Greene, D. [Lawrence Berkeley National Lab., CA (United States); Miller, P. [Natural Resources Defense Council (United States); Motau, C. [South African Center for Essential Community Services (South Africa); Stevens, F. [Durban Metro Water (South Africa)

    1997-09-01

    A recently invented device, ``UV Waterworks,`` uses ultraviolet (UV) light to disinfect drinking water. Its novel features are: low cost, robust design, rapid disinfection, low electricity use, low maintenance, high flow rate and ability to work with unpressurized water sources. The device could service a community of 1,000 persons, at an annual total cost of less than 10 US cents per person. UV Waterworks has been successfully tested in the laboratory. Limited field trials of an early version of the device were conducted in India in 1994--95. Insights from these trials led to the present design. Extended field trials of UV Waterworks, initiated in South Africa in February 1997, will be coordinated by the South African Center for Essential Community Services (SACECS), with technical and organizational support from Lawrence Berkeley National Laboratory(LBNL) and the Natural Resources Defense Council (both US). The first of the eight planned sites of the year long trial is an AIDS hospice near Durban. Durban metro Water and LBNL lab-tested a UV Waterworks unit prior to installing it at the hospice in August, 1997. The authors describe the field test plans and preliminary results from Durban.

  12. Integrated Disinfection By-Products Mixtures Research: Concentration by Reverse Osmosis Membrane Techniques of Disinfection By-Products from Water Disinfected by Chlorination and Ozonation/Postchlorination

    Science.gov (United States)

    To conduct the health-effect studies described in subsequent articles in this series, concentrated aqueous mixtures of disinfection by-products were required for the two water treatment trains described in the preceding article (Miltner et al., 2008). To accomplish this, the fini...

  13. Hardness of heat-polymerized acrylic resins after disinfection and long-term water immersion.

    Science.gov (United States)

    Neppelenbroek, Karin Hermana; Pavarina, Ana Cláudia; Vergani, Carlos Eduardo; Giampaolo, Eunice Teresinha

    2005-02-01

    In selecting a disinfectant for dental prostheses, compatibility between the disinfectant and the type of denture base material must be considered to avoid adverse effects on the hardness of the acrylic resin. This study investigated the hardness of 2 denture base resins after disinfection and long-term water immersion. Thirty-two disk-shaped specimens (13 mm in diameter and 8 mm thick) were fabricated from each resin (Lucitone 550 and QC-20), polished, stored in water at 37 degrees C for 48 hours, and submitted to hardness tests (Vickers hardness number [VHN]) before disinfection. Disinfection methods included scrubbing with 4% chlorhexidine gluconate for 1 minute, immersion for 10 minutes in 1 of the tested disinfectant solutions (n=8) (3.78% sodium perborate, 4% chlorhexidine gluconate, or 1% sodium hypochorite), and immersion in water for 3 minutes. The disinfection procedures were repeated 4 times, and 12 hardness measurements were made on each specimen. Control specimens (not disinfected) were stored in water for 56 minutes. Hardness tests (VHN) were also performed after 15, 30, 60, 90, and 120 days of storage in water. Statistical analyses of data were conducted with a repeated measures 3-way analysis of variance (ANOVA) and Tukey post-hoc test (alpha=.05). Mean values +/- SD for Lucitone 550 (16.52 +/- 0.94 VHN) and QC-20 (9.61 +/- 0.62 VHN) demonstrated a significant (P disinfection, regardless of material and disinfectant solutions used (Lucitone 550: 15.25 +/- 0.74; QC-20: 8.09 +/- 0.39). However, this effect was reversed after 15 days of storage in water. Both materials exhibited a continuous increase (P disinfection regardless of the disinfectant solution used.

  14. Disinfection for small water supplies: a technical guide

    CSIR Research Space (South Africa)

    Solsona, F

    1990-01-01

    Full Text Available This guide will present some disinfection systems, which will be useful in supporting disinfection programmes. The description of the different systems will provide a guideline for the selection of equipment base on balancing the simplicity...

  15. Chloraminated Concentrated Drinking Water for Disinfection Byproduct Mixtures Research: Evaluating Free Chlorine Contact Times

    Science.gov (United States)

    Complex mixtures of disinfection by-products (DBPs) are formed when the disinfectant oxidizes constituents (e.g., natural organic matter (NOM) and organic pollutants) present in the source water. Since 1974, over 600 DBPs have been identified in drinking water, yet a large portio...

  16. Chloramination of Concentrated Drinking Water: Evaluation of Disinfection Byproduct Formation and Dosing Scenarios - Portland

    Science.gov (United States)

    Complex mixtures of disinfection by-products (DBPs) are formed when the disinfectant oxidizes constituents (e.g., natural organic matter (NOM) and organic pollutants) found in the source water. Since 1974, over 600 DBPs have been identified in drinking water. Despite intense iden...

  17. Why Do People Stop Treating Contaminated Drinking Water with Solar Water Disinfection (SODIS)?

    Science.gov (United States)

    Tamas, Andrea; Mosler, Hans-Joachim

    2011-01-01

    Solar Water Disinfection (SODIS) is a simple method designed to treat microbiologically contaminated drinking water at household level. This article characterizes relapse behavior in comparison with continued SODIS use after a 7-month nonpromotion period. In addition, different subtypes among relapsers and continuers were assumed to diverge mainly…

  18. Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water.

    Science.gov (United States)

    Ufermann, Petra; Petersen, Hauke; Exner, Martin

    2011-12-01

    The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions

  19. Optimizing the solar water disinfection (SODIS) method by decreasing turbidity with NaCl

    OpenAIRE

    Dawney, Brittney; Pearce, Joshua

    2012-01-01

    International audience; Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (

  20. Disinfection of bore well water with chlorine dioxide/sodium hypochlorite and hydrodynamic cavitation.

    Science.gov (United States)

    Wang, Yifei; Jia, Aiyin; Wu, Yue; Wu, Chunde; Chen, Lijun

    2015-01-01

    The effect of hydrodynamic cavitation (HC) on potable water disinfection of chemicals was investigated. The bore well water was introduced into HC set-up to examine the effect of HC alone and combination of HC and chemicals such as chlorine dioxide and sodium hypochlorite. The effect of inlet pressure and geometrical parameters on disinfection was studied using HC alone and the results showed that increasing inlet pressure and using more and bigger holes of orifice plates can result in a higher disinfection rates. When HC was combined with chemicals, HC can reduce the doses of the chemicals and shorten the time of disinfection. It was also found that the decrease in bacteria concentration followed a first-order kinetic model. As for the experiment of combination of HC and sodium hypochlorite for disinfection, HC not only improves the disinfection rate but also degrades natural organic matter and chloroform. Compared with only sodium hypochlorite disinfection, combined processes get higher disinfection rate and lower production of chloroform, particularly the pretreatment with HC enhances the disinfection rate by 32% and there is a simultaneous reduction in production of chloroform by 39%.

  1. Spatial and temporal evaluations of disinfection by-products in drinking water distribution systems in Beijing, China.

    Science.gov (United States)

    Wei, Jianrong; Ye, Bixiong; Wang, Wuyi; Yang, Linsheng; Tao, Jing; Hang, Zhiyu

    2010-09-15

    Disinfection by-products were determined in 15 water treatment plants in Beijing City. The effects of different water sources (surface water source, mixture water source and ground water source), seasonal variation and spatial variation were examined. Trihalomethanes and haloacetic acids were the major disinfection by-products found in all treated water samples, which accounted for 42.6% and 38.1% of all disinfection by-products respectively. Other disinfection by-products including haloacetonitriles, chloral hydrate, haloketones and chloropicrin were usually detected in treated water samples but at lower concentrations. The levels of disinfection by-products in drinking water varied with different water sources and followed the order: surface water source > mixture water source > ground water source. High spatial and seasonal variation of disinfection by-products in the drinking water of Beijing was shown as a result. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Effect of Disinfectants on Preventing the Cross-Contamination of Pathogens in Fresh Produce Washing Water.

    Science.gov (United States)

    Banach, Jennifer L; Sampers, Imca; Van Haute, Sam; van der Fels-Klerx, H J Ine

    2015-07-23

    The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water disinfectants during produce processing with the aim to prevent cross-contamination of pathogens. Process wash water disinfection requires short contact times so microorganisms are rapidly inactivated. Free chlorine, chlorine dioxide, ozone, and peracetic acid were considered suitable disinfectants. A disinfectant's reactivity with the organic matter will determine the disinfectant residual, which is of paramount importance for microbial inactivation and should be monitored in situ. Furthermore, the chemical and worker safety, and the legislative framework will determine the suitability of a disinfection technique. Current research often focuses on produce decontamination and to a lesser extent on preventing cross-contamination. Further research on a sanitizer's efficacy in the washing water is recommended at the laboratory scale, in particular with experimental designs reflecting industrial conditions. Validation on the industrial scale is warranted to better understand the overall effects of a sanitizer.

  3. Efficacy of detergent and water versus bleach for disinfection of direct contact ophthalmic lenses.

    Science.gov (United States)

    Abbey, Ashkan M; Gregori, Ninel Z; Surapaneni, Krishna; Miller, Darlene

    2014-06-01

    Although manufacturers recommend cleaning ophthalmic lenses with detergent and water and then with a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus that of bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus and 2 viral strains (adenovirus and herpes simplex virus [HSV] type-1) were individually inoculated onto 20 gonioscopy and laser lenses. The lenses were washed with detergent and water and then disinfected with 10% bleach. All the lenses were cultured after inoculation, after washing with detergent and water, and after disinfecting with the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks, and viral cultures were observed for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). All 20 lenses inoculated with S. epidermidis, C. straitum, adenovirus, and HSV-1 showed growth after inoculation but no growth after washing with detergent/water and after disinfecting with the bleach. All lenses showed positive HSV and adenovirus PCR results after inoculation and negative PCR results after washing with detergent/water and after disinfecting with bleach. All methicillin-resistant S. aureus-contaminated lenses showed growth after inoculation and no growth after washing with detergent and water. However, 1 lens showed positive growth after disinfecting with bleach. Cleaning with detergent and water seemed to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage.

  4. Genotoxicity of drinking water treated with different disinfectants and effects of disinfection conditions detected by umu-test.

    Science.gov (United States)

    Nie, Xuebiao; Liu, Wenjun; Zhang, Liping; Liu, Qing

    2017-06-01

    The genotoxicity of drinking water treated with 6 disinfection methods and the effects of disinfection conditions were investigated using the umu-test. The pretreatment procedure of samples for the umu-test was optimized for drinking water analysis. The results of the umu-test were in good correlation with those of the Ames-test. The genotoxicity and production of haloacetic acids (HAAs) were the highest for chlorinated samples. UV+chloramination is the safest disinfection method from the aspects of genotoxicity, HAA production and inactivation effects. For chloramination, the effects of the mass ratio of Cl 2 to N of chloramine on genotoxicity were also studied. The changes of genotoxicity were different from those of HAA production, which implied that HAA production cannot represent the genotoxic potential of water. The genotoxicity per chlorine decay of chlorination and chloramination had similar trends, indicating that the reaction of organic matters and chlorine made a great contribution to the genotoxicity. The results of this study are of engineering significance for optimizing the operation of waterworks. Copyright © 2016. Published by Elsevier B.V.

  5. Establishing Solar Water Disinfection as a water treatment method at ...

    African Journals Online (AJOL)

    1.1 billion People worldwide do not have access to safe drinking water and therefore are exposed to a high risk for diarrhoeal diseases. As a consequence, about 6,000 children die each day of dehydration due to diarrhoea. Adequate water treatment methods and safe storage of drinking water, combined with hygiene ...

  6. Oxidation of the antibacterial agent norfloxacin during sodium hypochlorite disinfection of marine culture water.

    Science.gov (United States)

    Zhang, Yuanyuan; Rong, Chuan; Song, Yanqun; Wang, Yinghui; Pei, Jiying; Tang, Xinying; Zhang, Ruijie; Yu, Kefu

    2017-09-01

    Chlorination disinfection and antibiotic addition are two universal processes of marine culture. The generation of disinfection byproducts (DBPs) is unavoidable. Antibiotic residue not only pollutes water but also acts as a precursor to the production of new DBPs. The fate of antibiotic norfloxacin (NOR) in chlorination disinfection was investigated. It was observed that NOR could be oxidized by disinfection agent sodium hypochlorite, but the oxidation rate varied considerably with the type of disinfected water. For fresh water, marine culture water and sea water, the reaction rate constant was 0.066 min(-1), 0.466 min(-1) and 1.241 min(-1), respectively. The difference was primarily attributed to the promotion role of bromide ions in seawater and marine culture water. Moreover, the bromide ions could result in the generation of brominated DBPs (Br-DBPs). The kinetics, products, reaction centers and mechanisms were investigated. The active site of NOR was found to be the N4 atom on piperazinyl in fresh water. During marine culture water and sea water disinfection, the carboxyl on NOR was oxidized and two Br-DBPs were formed. This was attributed to the lowering of the reaction's required activation energy when performed in the presence of bromide ions. The Br-DBPs were also confirmed in real shrimp pond brackish water. Quantitative structure activity relationships and the total organic halogen analysis showed that the DBPs in marine culture water possessed stronger toxicological properties than the DBPs in fresh water. The toxicity increase was attributed to the production of Br-DBPs in the disinfection process of marine culture water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Batch process solar disinfection is an efficient means of disinfecting drinking water contaminated with Shigella dysenteriae type I.

    Science.gov (United States)

    Kehoe, S C; Barer, M R; Devlin, L O; McGuigan, K G

    2004-01-01

    The mortality and morbidity rate caused by Shigella dysenteriae type I infection is increasing in the developing world each year. In this paper, the possibility of using batch process solar disinfection (SODIS) as an effective means of disinfecting drinking water contaminated with Sh. dysenteriae type I is investigated. Phosphate-buffered saline contaminated with Sh. dysenteriae type I was exposed to simulated solar conditions and the inactivation kinetics of this organism was compared with that of Sh. flexneri, Vibrio cholerae and Salmonella typhimurium. Recovery of injured Sh. dysenteriae type I may be improved by plating on medium supplemented with catalase or pyruvate. Sh. dysenteriae type I is very sensitive to batch process SODIS and is easily inactivated even during overcast conditions. Batch process SODIS is an appropriate intervention for use in developing countries during Sh. dysenteriae type I epidemics.

  8. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  9. Life Cycle Environmental Impacts of Disinfection Technologies Used in Small Drinking Water Systems.

    Science.gov (United States)

    Jones, Christopher Holladay; Shilling, Elizabeth G; Linden, Karl G; Cook, Sherri Michelle

    2018-02-05

    Small drinking water systems serve a fifth of the U.S. population and rely heavily on disinfection. While chlorine disinfection is common, there is interest in minimizing chemical addition, especially due to carcinogenic disinfection byproducts and chlorine-resistant pathogens, by using ultraviolet technologies; however, the relative, broader environmental impacts of these technologies are not well established, especially in the context of small (water systems. The objective of this study was to identify environmental trade-offs between chlorine and ultraviolet disinfection via comparative life cycle assessment. The functional unit was the production of 1 m3 of drinking water to U.S. Treatment included cartridge filtration followed by either chlorine disinfection or ultraviolet disinfection with chlorine residual addition. Environmental performance was evaluated for various chlorine contact zone materials (plastic, concrete, steel), ultraviolet validation factors (1.2 to 4.4), and electricity sources (renewable; U.S. average, high, and low impact grids). Performance was also evaluated when filtration and chlorine residual were not required. From an LCA perspective, replacing chlorine with UV was preferred only in a limited number of cases (i.e., high pumping pressure but filtration is not required). In all others, chlorine was environmentally preferred, although some contact zone materials and energy sources had an impact on the comparison. Utilities can use these data to inform their disinfection technology selection and operation to minimize environmental and human health impacts.

  10. Disinfection of dental unit water line using aloe vera: in vitro study.

    Science.gov (United States)

    Pareek, Sonia; Nagaraj, Anup; Sharma, Prateek; Atri, Mansi; Walia, Satinder; Naidu, Shravani; Yousuf, Asif

    2013-01-01

    Context. Dental unit waterlines may be heavily contaminated with microorganisms and are a potential source of infection for both practicing staff and immunocompromised patients particularly. Contamination of dental unit water lines could be inhibited with the use of disinfectants. The present study investigates the effect of aloe-vera-based disinfectant in reducing the microbial growth in dental unit water lines (DUWLs). Aims. To compare the efficacy of aloe vera, hydrogen peroxide (H2O2), and 5% sodium hypochlorite (NaOCl) in controlling microbial contamination of DUWLs. Materials and Methods. After obtaining baseline water samples, the dental unit waterlines were treated with aloe vera, 10% hydrogen peroxide, and 5% sodium hypochlorite. Each of the three disinfectants was used in increasing concentrations and their inhibiting effect was compared. Water samples were analyzed for microbiological quality by the total viable count (TVC) method. Statistical Analysis Used. SPSS 16. Results. There was significant reduction in mean CFU/ml when treated with disinfectants each for a period of one week. Aloe-vera solution was found to be the most effective in reducing the microbial colonies. Conclusions. Improving the water quality from dental unit water lines is of considerable importance; chemical-based disinfectants can be replaced with herbal disinfectants for treating microbial contamination in dental unit waterlines.

  11. Effect of Disinfectants on Preventing the Cross-Contamination of Pathogens in Fresh Produce Washing Water

    Directory of Open Access Journals (Sweden)

    Jennifer L. Banach

    2015-07-01

    Full Text Available The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water disinfectants during produce processing with the aim to prevent cross-contamination of pathogens. Process wash water disinfection requires short contact times so microorganisms are rapidly inactivated. Free chlorine, chlorine dioxide, ozone, and peracetic acid were considered suitable disinfectants. A disinfectant’s reactivity with the organic matter will determine the disinfectant residual, which is of paramount importance for microbial inactivation and should be monitored in situ. Furthermore, the chemical and worker safety, and the legislative framework will determine the suitability of a disinfection technique. Current research often focuses on produce decontamination and to a lesser extent on preventing cross-contamination. Further research on a sanitizer’s efficacy in the washing water is recommended at the laboratory scale, in particular with experimental designs reflecting industrial conditions. Validation on the industrial scale is warranted to better understand the overall effects of a sanitizer.

  12. Chlorine dioxide as a disinfectant for Ralstonia solanacearum control in water, storage and equipment

    Directory of Open Access Journals (Sweden)

    Popović Tatjana

    2016-01-01

    Full Text Available Brown rot or bacterial wilt caused by bacterium Ralstonia solanacearum is the main limiting factor in potato production. Quarantine measures are necessary to avoid spread of disease to disease-free areas. R. solanacearum has been shown to contaminate watercourses from which crop irrigation is then prohibited causing further potential losses in yield and quality. The bacteria also spread via surfaces that diseased seed potatoes come into contact with. This study showed bactericidal activity of chlorine dioxide (CIO2 on R. solanacearum for disinfection of water, surface and equipment. The results showed that CIO2 solution at concentration of 2 ppm at 30 minutes of exposure time had bactericidal effect for disinfection of water. For surface and equipment disinfection, concentration of 50 ppm showed total efficacy at 30 min and 5 sec exposure time, respectively. Results suggest that use of CIO2 as a disinfectant has a potential for control of brown rot pathogen in water, storage and equipment.

  13. Bactericidal Effect of Solar Water Disinfection under Real Sunlight Conditions▿

    Science.gov (United States)

    Boyle, M.; Sichel, C.; Fernández-Ibáñez, P.; Arias-Quiroz, G. B.; Iriarte-Puña, M.; Mercado, A.; Ubomba-Jaswa, E.; McGuigan, K. G.

    2008-01-01

    Batch solar disinfection (SODIS) inactivation kinetics are reported for suspensions in water of Campylobacter jejuni, Yersinia enterocolitica, enteropathogenic Escherichia coli, Staphylococcus epidermidis, and endospores of Bacillus subtilis, exposed to strong natural sunlight in Spain and Bolivia. The exposure time required for complete inactivation (at least 4-log-unit reduction and below the limit of detection, 17 CFU/ml) under conditions of strong natural sunlight (maximum global irradiance, ∼1,050 W m−2 ± 10 W m−2) was as follows: C. jejuni, 20 min; S. epidermidis, 45 min; enteropathogenic E. coli, 90 min; Y. enterocolitica, 150 min. Following incomplete inactivation of B. subtilis endospores after the first day, reexposure of these samples on the following day found that 4% (standard error, 3%) of the endospores remained viable after a cumulative exposure time of 16 h of strong natural sunlight. SODIS is shown to be effective against the vegetative cells of a number of emerging waterborne pathogens; however, bacterial species which are spore forming may survive this intervention process. PMID:18359829

  14. Technological prospection on membranes containing silver nanoparticles for water disinfection.

    Science.gov (United States)

    Linhares, Aline Marques Ferreira; Grando, Rafaela Lora; Borges, Cristiano Piacsek; da Fonseca, Fabiana Valéria

    2017-09-20

    Membrane separation is an established technological process, and since the 1980s it has been used commercially at large industrial plants worldwide. Water and wastewater disinfection are one of the applications of membrane technologies, but fouling and biofouling are still a challenge for the sector. The use of silver nanoparticles in membranes because of their biocidal action has attracted research interest. This technology foresight study investigates the academic literature and patenting activity to map out the technological progress and difficulties in the area. One hundred and sixty-seven articles on the subject published between 2005 and 2017 were retrieved, and it was found that the greatest number of publications occurred in 2016. A wide range of materials being used to make membranes and institutions involved in researching this technology were identified. Fifty-nine patents of relevance were also retrieved, with 2011 and 2013 seeing the highest number of patent applications filed. The countries with the most academic output and priority patents are the United States and China, but no institution stands out from the others in the area. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  15. Bactericidal effect of solar water disinfection under real sunlight conditions.

    Science.gov (United States)

    Boyle, M; Sichel, C; Fernández-Ibáñez, P; Arias-Quiroz, G B; Iriarte-Puña, M; Mercado, A; Ubomba-Jaswa, E; McGuigan, K G

    2008-05-01

    Batch solar disinfection (SODIS) inactivation kinetics are reported for suspensions in water of Campylobacter jejuni, Yersinia enterocolitica, enteropathogenic Escherichia coli, Staphylococcus epidermidis, and endospores of Bacillus subtilis, exposed to strong natural sunlight in Spain and Bolivia. The exposure time required for complete inactivation (at least 4-log-unit reduction and below the limit of detection, 17 CFU/ml) under conditions of strong natural sunlight (maximum global irradiance, approximately 1,050 W m(-2) +/- 10 W m(-2)) was as follows: C. jejuni, 20 min; S. epidermidis, 45 min; enteropathogenic E. coli, 90 min; Y. enterocolitica, 150 min. Following incomplete inactivation of B. subtilis endospores after the first day, reexposure of these samples on the following day found that 4% (standard error, 3%) of the endospores remained viable after a cumulative exposure time of 16 h of strong natural sunlight. SODIS is shown to be effective against the vegetative cells of a number of emerging waterborne pathogens; however, bacterial species which are spore forming may survive this intervention process.

  16. [The use of UV rays for the disinfection of water. I. Microbiologic studies of drinking water].

    Science.gov (United States)

    Martiny, H; Wlodavezyk, K; Harms, G; Rüden, H

    1988-01-01

    As a physical disinfection method without chemicals required the ultraviolet irradiation was tested for disinfection of drinking water. The survival was measured as a function of exposure to radiation for S. enteritidis, E. cloacae, C. freundii, S. marcescens, E. coli, K. pneumoniae und S. faecium. The bacteria were grown in trypton soya broth until they were well into the exponential phase. Two different UV-disinfection units were tested. Both consist of cylindrical shaped chambers with one low-pressure mercury-discharge lamp with their longitudinal axis parallel to the chambers. With 10(6) cfu/ml the experiments were done with three different rates of flow of 7,2 m3/h, 4,0 m3/h and 2,0 m3/h. The minimum exposures to radiation necessary to cause a 99.999% reduction were 10-86 mWs/cm2 depending on the test bacterium and on the UV-disinfection unit. The minimum doses ranged for S. enteritidis up to 13 mWs/cm2, for E. coli up to 21 mWs/cm2, for K. pneumoniae up to 39 mWs/cm2, for S. faecium up to 42 mWs/cm2, for E. cloacae up to 43 mWs/cm2, for C. freundii up to 72 mWs/cm2, and for S. marcescens up to 86 mWs/cm2.

  17. Effect of Disinfectants on Preventing the Cross-Contamination of Pathogens in Fresh Produce Washing Water

    NARCIS (Netherlands)

    Banach, J.L.; Sampers, I.; Haute, van S.; Fels, van der H.J.

    2015-01-01

    The potential cross-contamination of pathogens between clean and contaminated produce in the washing tank is highly dependent on the water quality. Process wash water disinfectants are applied to maintain the water quality during processing. The review examines the efficacy of process wash water

  18. Solar disinfection of water for low income communities; Desinfeccao solar de agua para comunidades de baixa renda

    Energy Technology Data Exchange (ETDEWEB)

    Felix, Lorna Falcao

    2010-03-15

    The use of solar energy for water disinfection, and is accessible to disadvantaged communities because of its low cost, has the advantage of using disposable materials such as bottles of polyethylene terephthalate (PET). We present a study that used two methods of disinfection: the methodology proposed by the project Solar Water Disinfection (SODIS), which consisted of water disinfection by solar radiation and temperature and the methodology which the temperature of the water for disinfection. In both, we seek to eliminate microorganisms that cause serious diseases such as dysentery, typhoid, cholera, etc. Water samples were collected in the community of Bass, where the population has low income and the incidence of waterborne diseases is high. The experiments were divided into two stages. In step 1 we studied the feasibility of disinfection and in step 2 the feasibility of the pilot plant to obtain adequate levels of disinfection temperatures desired. The results showed the efficiency of the disinfection process, reaching an average of 80 to 100% death of microorganisms, but regrowth was observed in some samples. Finally on the good results of stage 1, is designed and built and tested in an experimental pilot plant, which has shown to be feasible to promote water disinfection through the use of solar energy. The water after treatment is in accordance with the limits established by Brazilian legislation for clean water, maintaining a positive performance for the disinfection and acceptable levels of bacterial regrowth. (author)

  19. [Comparison of the effects of chlorine dioxide, sodium hypochlorite and their combination on simulative water disinfection].

    Science.gov (United States)

    Wang, Ying; Li, Na; Lu, Yi; Wang, Yazhou

    2008-05-01

    To compare the effects of disinfection of chlorine dioxide (ClO2), sodium hypochlorite(NaClO) and their combination (ClO + NaClO) on simulative water samples. The simulative water samples containing 5.0 x 10(4) - 5.0 x 10(5) cfu/100ml Escherichia coli were prepared in laboratory and disinfected by different doses of chlorine dioxide, sodium hypochlorite and their combination for 60, 60, 30 + 60 min respectively. The kill ratio for Escherichia coli, and the residual chlorine dioxide, and the product of chlorite ion (ClO2-) and total residual chlorine were detected and compared by the membrane filter(MF) technique and electrometric titration. The minimum effective dosage (MED) for disinfect of simulative water samples were 0.4 mg/L of chlorine dioxide, 0.5 mg/L of sodium hypochlorite, and the 0.1 mg/L + 0.3 mg/L or 0.2 mg/L + 0.2 mg/L of their combination. By comparision with disinfection of ClO2 and NaClO alone, the residual chlorine dioxide increased 13.43% - 166.67% in simulative water sample under disinfection by the combination of ClO2 + NaClO, While chlorite ion decreased 13.11% - 19.97% and total residual chlorine increased 9.34% - 40.15%. The combination of chlorine dioxide and sodium hypochlorite for disinfection of drinking water could achieve better effect of disinfection and decrease disinfection by-products as well.

  20. A practical demonstration of water disinfection using TiO2 films and sunlight.

    Science.gov (United States)

    Gelover, Silvia; Gómez, Luis A; Reyes, Karina; Teresa Leal, Ma

    2006-10-01

    The scope of this study is the assessment of the efficiency of solar disinfection by heterogeneous photocatalysis with sol-gel immobilized (titanium dioxide) TiO2 films over glass cylinders. The solar disinfection process known as SODIS was considered as a reference. Spring water naturally polluted with coliform bacteria was exposed to sunlight in plastic bottles with and without TiO2 over simple solar collectors and the disinfection effectiveness was measured. Total and fecal coliforms quantification was performed by means of the chromogenic substrate method in order to obtain the efficiency of each disinfection treatment. The disinfection with TiO2 was more efficient than the SODIS process, inactivating total coliforms as well as fecal coliforms. On a sunny day (more than 1000 W m(-2) irradiance), it took the disinfection with immobilized TiO2 15 min of irradiation to inactivate the fecal coliforms to make them undetectable. For inactivation of total coliforms, 30 min was required, so that in less than half the time it takes SODIS, the treated water complies with the microbial standards for drinking water in Mexico. Another important part of this study has been to determine the bacterial regrowth in water after the disinfection processes were tested. After SODIS, bacterial regrowth of coliforms was observed. In contrast, when using the TiO2 catalyst, coliforms regrowth was not detected, neither for total nor for fecal coliforms. The disinfection process using TiO2 kept treated water free of coliforms at least for seven days after sun irradiation. This demonstration opens the possibility of application of this simple method in rural areas of developing countries.

  1. PLAN OF ACTIONS TO PREVENT, CONTROL AND DESINFECT CONTAMINATED PRODUCTS OF FUNGI AND AFLATOXINS

    OpenAIRE

    Armijo C., J.; Departamento Académico de Operaciones Unitarias, Facultad de Química e Ing. Química Universidad Nacional Mayor de San Marcos Lima, Perú; Calderón, J.; Departamento Académico de Operaciones Unitarias, FQIQ, Universidad Nacional Mayor de San Marcos, Lima, Perú

    2014-01-01

    Aflatoxins, a group of highly toxic substances produced by certain species of Aspergillus, especially A. flavus, have been found to occur in agricultural products such as corn, peanuts, cotton seed, animal feed, and many varieties of nuts. Experimental studies show that aflatoxins are carcinogenic. This paper proposes a plan of actions to prevent, control and desinfecting products contaminated with aflatoxins. Post harvest treatment of the product involves drying and storage temperature of 5 ...

  2. [The problem in the reactivation of microorganisms on evaluating the efficacy of water disinfectants].

    Science.gov (United States)

    Artemova, T Z; Nedachin, A E; Zholdakova, Z I; Sinitsyna, O O; Gipp, E K; Butorina, N N; Mamonov, R A; Tul'skaia, E A

    2010-01-01

    The investigation deals with the topical problem of whether bacterial viability and properties may be restored after the achieved bacteriostatic effect of water disinfection, which reduces the reliability of the control and adequate assessment of its epidemic safety. The objective of the investigation was to study whether bacteria might be reactivated in the estimation of water disinfection with guanidine-containing agents as an alternative to chlorine. Experiments were carried out on the waters from model water reservoirs, by simulating water contamination with residential waste waters and on the natural water from the Moscow River, by reproducing the purification conditions: coagulation, filtration, disinfection with a binary mixture of polyhexamethyleneguanidine hydrochloride and quaternary ammonium compound. The experimental studies of the efficacy of the binary agent against indicator, opportunistic, and pathogenic bacteria indicated that the viability of bacterial cells might be reactivated and restored after water disinfection and cell multiplication upon further exposure. Microorganisms that had the greatest capacity for reactivation after use of the binary agent, as evidenced by the group values of the total number of saprophytes (microbial number) at 37 degrees C, coliform bacteria, and Pseudomonas aeruginosa, were identified. The findings show it necessary to consider reactivation processes in the evaluation of novel disinfectants, which requires a supplemented procedure for obligatorily estimating their exposure 24 hours after use of a reagent.

  3. Chemical Identification and Flavor Profile Analysis of Iodinated Phenols Produced From Disinfection of Spacecraft Drinking Water

    OpenAIRE

    Mirlohi, Susan

    1997-01-01

    The National Aeronautics and Space Administration (NASA) is considering the use of iodine for disinfection of recycled wastewater and potable water in the International Space Station (ISS). Like Chlorine and other halogen compounds, iodine can form disinfection by-products (DBPs) in the presence of organic compounds. Recycled wastewater sources proposed for reuse in the space station include laundry, urine, and humidity condensate. These contain large concentrations of iodine-demanding compou...

  4. Optimization of fixed titanium dioxide film on PET bottles and visual indicator for water disinfection

    Science.gov (United States)

    Heredia-Munoz, Manuel Antonio

    Water is perhaps the most important resource that sustains human life. According to the World Health Organization (WHO), almost two billion people do not have access to the required water that is needed to satisfy their daily needs and one billion do not have access to clean sources of water for consumption, most of them living in isolated and poor areas around the globe. Poor quality water increases the risk of cholera, typhoid fever and dysentery, and other water-borne illness making this problem a real crisis that humankind is facing. Several water disinfection technologies have been proposed as solutions for this problem. Solar water disinfection using TiO2 coated PET bottles was the alternative that is studied in this work. This technology does not only inactivate bacteria but also disintegrates organic chemicals that can be present in water. The objectives of this work address the optimization of the TiO 2 coated PET bottles technologies. The improvement on the bottle coating process, using two coats of 10% W/V of TiO2 in a solution of vinegar and sodium bicarbonate to form the TiO2 film, the use of a different indigo carmine (1.25 X 10-1mg/pill) concentration in the pill indicator of contamination, the increase of the disinfection rate through shaking the bottles, degradation under intermittent UV radiation and the effect of bottle size on photocatalytic water disinfection were among the most important findings. A new mathematical model that describes better photocatalytic water disinfection in TiO2 coated bottles and simulates water disinfection under different working conditions was another important achievement. These results can now be used to design a strategy for disseminating this technology in areas where it is required and, in that way, generate the greatest positive impact on the people needing safe drinking water.

  5. Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine.

    Science.gov (United States)

    Kahler, Amy M; Cromeans, Theresa L; Metcalfe, Maureen G; Humphrey, Charles D; Hill, Vincent R

    2016-06-01

    It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.

  6. Disinfection by-products and extractable organic compounds in South African tap water

    Directory of Open Access Journals (Sweden)

    Carien Nothnagel

    2008-04-01

    Full Text Available An important step in urban purification of drinking water is disinfection by e.g. chlorination where potential pathogenic micro-organisms in the water supply are killed. The presence of organic material in natural water leads to the formation of organic by- products during disinfection. Over 500 of these disinfection by-products (DBPs have been identified and many more are estimated to form during the disinfection step. Several DBPs such as trihalomethanes (THMs, which is carcinogenic, poses serious health risks to the community. There is very few quantitative data available which realizes the actual levels of these compounds present in drinking water. The levels of four THMs present in drinking water were measured. It included chloroform, bromodichloromethane, chlorodibromomethane and bromoform. Although microbiological parameters are considered to get more attention than disinfection by-products, the measurement of the levels of these compounds in South-African drinking water is essential together with establishing minimum acceptable concentration levels. The target range for total trihalomethanes (TTHMs established by the US EPA at the end of 2003 is 0-0.08ug/mL. The aim of this paper is to create an awareness of the problem as well as presenting preliminary results obtained with the method of analysis. Preliminary results indicate that urgent attention must be given to the regulation and monitoring of DBPs in South African drinking water.

  7. The effect of chlorine and combined chlorine/UV treatment on coliphages in drinking water disinfection.

    Science.gov (United States)

    Zyara, Alyaa M; Torvinen, Eila; Veijalainen, Anna-Maria; Heinonen-Tanski, Helvi

    2016-08-01

    Chlorine disinfection is a globally used method to ensure the safety of drinking water. However, it has not always been successful against viruses and, therefore, it is important to find new methods to disinfect water. Seventeen different coliphages were isolated from the treated municipal wastewater. These coliphages and MS2 were treated with different dosages of chlorine in drinking water, and a combined chlorine/ultraviolet irradiation treatment for the chlorine-resistant coliphages. Chlorine disinfection with 0.3-0.5 mg/L total chlorine (free Cl-dosage 0.12-0.21 mg/L) for 10 min achieved 2.5-5.7 Log10-reductions for 11 sensitive coliphages. The six most resistant coliphages showed no reduction with these chlorine concentrations. MS2 was intermediate in chlorine resistance, and thus it is not a good indicator for viruses in chlorine disinfection. In the combined treatment total chlorine of 0.05-0.25 mg/L (free Cl-dosage 0.02-0.08 mg/L) and ultraviolet irradiation (14-22 mWs/cm(2)) were more effective than chlorine alone, and 3-5 Log10-reductions were achieved for the chlorine-resistant strains. The chlorination efficiency could be increased by higher dosages and longer contact times, but this could increase the formation of disinfection by-products. Therefore, the combination treatment is a recommended disinfection method.

  8. Formation and modeling of disinfection by-products in drinking water of six cities in China.

    Science.gov (United States)

    Ye, Bixiong; Wang, Wuyi; Yang, Linsheng; Wei, Jianrong; E, Xueli

    2011-05-01

    Water quality parameters including TOC, UV(254), pH, chlorine dosage, bromide concentration and disinfection by-products were measured in water samples from 41 water treatment plants of six selected cities in China. Chloroform, bromodichloromethane, dibromochloromethane, dichloroacetic acid and trichloroacetic acid were the major disinfection by-products in the drinking water of China. Bromoform and dibromoacetic acid were also detected in many water samples. Higher concentrations of trihalomethanes and haloacetic acids were measured in summer compared to winter. The geographical variations in DBPs showed that TTHM levels were higher in Zhengzhou and Tianjin than other selected cities. And the HAA5 levels were highest in Changsha and Tianjin. The modeling procedure that predicts disinfection by-products formation was studied and developed using artificial neural networks. The performance of the artificial neural networks model was excellent (r > 0.84).

  9. Attitudinal and Relational Factors Predicting the Use of Solar Water Disinfection: A Field Study in Nicaragua

    Science.gov (United States)

    Altherr, Anne-Marie; Mosler, Hans-Joachim; Tobias, Robert; Butera, Fabrizio

    2008-01-01

    Solar water disinfection (SODIS) is an uncomplicated and cheap technology providing individuals with safe drinking water by exposing water-filled plastic bottles to sunlight for 6 hours to kill waterborne pathogens. Two communities were visited, and 81 families (40 SODIS users and 41 nonusers) were interviewed. The relationship between several…

  10. Response of Simulated Drinking Water Biofilm Mechanical and Structural Properties to Long-Term Disinfectant Exposure.

    Science.gov (United States)

    Shen, Yun; Huang, Conghui; Monroy, Guillermo L; Janjaroen, Dao; Derlon, Nicolas; Lin, Jie; Espinosa-Marzal, Rosa; Morgenroth, Eberhard; Boppart, Stephen A; Ashbolt, Nicholas J; Liu, Wen-Tso; Nguyen, Thanh H

    2016-02-16

    Mechanical and structural properties of biofilms influence the accumulation and release of pathogens in drinking water distribution systems (DWDS). Thus, understanding how long-term residual disinfectants exposure affects biofilm mechanical and structural properties is a necessary aspect for pathogen risk assessment and control. In this study, elastic modulus and structure of groundwater biofilms was monitored by atomic force microscopy (AFM) and optical coherence tomography (OCT) during three months of exposure to monochloramine or free chlorine. After the first month of disinfectant exposure, the mean stiffness of monochloramine- or free-chlorine-treated biofilms was 4 to 9 times higher than those before treatment. Meanwhile, the biofilm thickness decreased from 120 ± 8 μm to 93 ± 6-107 ± 11 μm. The increased surface stiffness and decreased biofilm thickness within the first month of disinfectant exposure was presumably due to the consumption of biomass. However, by the second to third month during disinfectant exposure, the biofilm mean stiffness showed a 2- to 4-fold decrease, and the biofilm thickness increased to 110 ± 7-129 ± 8 μm, suggesting that the biofilms adapted to disinfectant exposure. After three months of the disinfectant exposure process, the disinfected biofilms showed 2-5 times higher mean stiffness (as determined by AFM) and 6-13-fold higher ratios of protein over polysaccharide, as determined by differential staining and confocal laser scanning microscopy (CLSM), than the nondisinfected groundwater biofilms. However, the disinfected biofilms and nondisinfected biofilms showed statistically similar thicknesses (t test, p > 0.05), suggesting that long-term disinfection may not significantly remove net biomass. This study showed how biofilm mechanical and structural properties vary in response to a complex DWDS environment, which will contribute to further research on the risk assessment and control of biofilm-associated-pathogens in DWDS.

  11. Differential toxicity of drinking water disinfected with combinations of ultraviolet radiation and chlorine.

    Science.gov (United States)

    Plewa, Michael J; Wagner, Elizabeth D; Metz, Deborah H; Kashinkunti, Ramesh; Jamriska, Katherine J; Meyer, Maria

    2012-07-17

    Alternative technologies to disinfect drinking water such as ultraviolet (UV) disinfection are becoming more widespread. The benefits of UV disinfection include reduced risk of microbial pathogens such as Cryptosporidium and reduced production of regulated drinking water disinfection byproducts (DBPs). The objective of this research was to determine if mammalian cell cytotoxicity and genotoxicity varied in response to different chlorination protocols with and without polychromatic medium pressure UV (MPUV) and monochromatic low pressure UV (LPUV) disinfection technologies. The specific aims were to analyze the mammalian cell cytotoxicity and genotoxicity of concentrated organic fractions from source water before and after chlorination and to determine the cytotoxicity and genotoxicity of the concentrated organic fractions from water samples treated with UV alone or UV before or after chlorination. Exposure of granular activated carbon-filtered Ohio River water to UV alone resulted in the lowest levels of mammalian cell cytotoxicity and genotoxicity. With combinations of UV and chlorine, the lowest levels of cytotoxicity and genotoxicity were observed with MPUV radiation. The best combined UV plus chlorine methodology that generated the lowest cytotoxicity and genotoxicity employed chlorination first followed by MPUV radiation. These data may prove important in the development of multibarrier methods of pathogen inactivation of drinking water, while limiting unintended toxic consequences.

  12. Reduced Efficiency of Chlorine Disinfection of Naegleria fowleri in a Drinking Water Distribution Biofilm.

    Science.gov (United States)

    Miller, Haylea C; Wylie, Jason; Dejean, Guillaume; Kaksonen, Anna H; Sutton, David; Braun, Kalan; Puzon, Geoffrey J

    2015-09-15

    Naegleria fowleri associated with biofilm and biological demand water (organic matter suspended in water that consumes disinfectants) sourced from operational drinking water distribution systems (DWDSs) had significantly increased resistance to chlorine disinfection. N. fowleri survived intermittent chlorine dosing of 0.6 mg/L for 7 days in a mixed biofilm from field and laboratory-cultured Escherichia coli strains. However, N. fowleri associated with an attached drinking water distribution biofilm survived more than 30 times (20 mg/L for 3 h) the recommended concentration of chlorine for drinking water. N. fowleri showed considerably more resistance to chlorine when associated with a real field biofilm compared to the mixed laboratory biofilm. This increased resistance is likely due to not only the consumption of disinfectants by the biofilm and the reduced disinfectant penetration into the biofilm but also the composition and microbial community of the biofilm itself. The increased diversity of the field biofilm community likely increased N. fowleri's resistance to chlorine disinfection compared to that of the laboratory-cultured biofilm. Previous research has been conducted in only laboratory scale models of DWDSs and laboratory-cultured biofilms. To the best of our knowledge, this is the first study demonstrating how N. fowleri can persist in a field drinking water distribution biofilm despite chlorination.

  13. Characterization of a stirred tank electrochemical cell for water disinfection processes

    Energy Technology Data Exchange (ETDEWEB)

    Polcaro, A.M. [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, p.zza D' Armi, 09123 Cagliari (Italy)]. E-mail: polcaro@dicm.unica.it; Vacca, A. [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, p.zza D' Armi, 09123 Cagliari (Italy); Mascia, M. [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, p.zza D' Armi, 09123 Cagliari (Italy); Palmas, S. [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, p.zza D' Armi, 09123 Cagliari (Italy); Pompei, R. [Dipartimento di Scienze e Tecnologie Biomediche, Universita degli Studi di Cagliari, via Porcell, 4-09123 Cagliari (Italy); Laconi, S. [Dipartimento di Scienze e Tecnologie Biomediche, Universita degli Studi di Cagliari, via Porcell, 4-09123 Cagliari (Italy)

    2007-02-01

    Laboratory experiments were performed to characterize the behaviour of an electrochemical cell equipped with boron-doped diamond anodes and to verify its effectiveness in water disinfection. The hydrodynamic regime was determined when the cell worked either in batch or in continuous mode. Galvanostatic electrolyses of aqueous 1 mM Na{sub 2}SO{sub 4} solutions were performed to investigate on the oxidant production in different experimental conditions. The same solutions contaminated by E. coli, enterococci and coliforms were used as test media to verify the effectiveness of the system in the disinfection process. Experimental results indicated that the major inactivation mechanism of bacteria in the electrochemical cell is a disinfection by electrochemically generated oxidants, however a cooperative effect of superficial reaction has to be taken into account. The great capability of BDD anode to produce reactive oxygen species (ROS) and other oxidizing species during the electrolysis allows to establish a chlorine-free disinfection process.

  14. Enhancing the Performance of Solar Water Disinfection with Potassium Persulfat: Laboratory Study with Enterococcus faecalis

    Directory of Open Access Journals (Sweden)

    Ghader Ghanizadeh

    2017-10-01

    Full Text Available Background & Aims of the Study: The safe drinking water providing is one of the most crucial objections in these centenaries. Bacterial water contamination and high rate of morbidity and mortality is crucial health threat. Efficiency of potassium persulfat (KPS associated solar disinfection as a novel water disinfection technology was evaluated in batch scale experiments, using Ent. faecalis (ATTCC 29212. Material and Methods: This research is a descriptive and experimental study which done on Tehran city, Iran. Ent. faecalis (ATTCC 29212 was provided in standard form from reference laboratory. Desired bacterial density in water was prepared by Mc Farland method. Water specimens were exhibited with solar radiations from 10 a.m to 16 p.m of Tehran local time. All experiments were conducted into 1.5 L volume of Damavand bottled water. Non-injured bacteria cells were detected by plating onto Bile Esculin azide agar media. Turbid water samples were provided by spiking of sterile slurry. Contact time (1-6 h, turbidity (30-200 NTU, KPS concentration (0.1, 0.7, 1.5 and 2 mMol/l, Ent. faecalis density(1000 and 1500 cell/ml and UV intensity  were independent and disinfection efficiency was a dependent variable, respectively. Results: Intensity of UVA solar irradiation varied from 3770 to 6263.3 µW/Cm2, with the highest value was measured on 13.30 p.m. In single SODIS and 1 hour contact time, increasing of bacterial closeness from 1000 to 1500 cell/ml implied disinfection performance decreasing in which, the vital bacteria was 10 and 20 cell/ml, respectively; but beyond of this contact time, a complete disinfection was occurred. Disinfection of Ent. faecalis was achieved within 2 h with single solar irradiation but KPS associated solar disinfection with applied dosage of KPS provide completely disinfection in 1 h in which the process efficiency was not influenced by increasing of bacterial density and turbidity up to 200 NTU. Conclusion: Association of

  15. A pilot study of solar water disinfection in the wilderness setting.

    Science.gov (United States)

    Tedeschi, Christopher M; Barsi, Christopher; Peterson, Shane E; Carey, Kevin M

    2014-09-01

    Solar disinfection of water has been shown to be an effective treatment method in the developing world, but not specifically in a wilderness or survival setting. The current study sought to evaluate the technique using materials typically available in a wilderness or backcountry environment. Untreated surface water from a stream in rural Costa Rica was disinfected using the solar disinfection (SODIS) method, using both standard containers as well as containers and materials more readily available to a wilderness traveler. Posttreatment samples using polyethylene terephthalate (PET) bottles, as well as Nalgene and Platypus water containers, showed similarly decreased levels of Escherichia coli and total coliforms. The SODIS technique may be applicable in the wilderness setting using tools commonly available in the backcountry. In this limited trial, specific types of containers common in wilderness settings demonstrated similar performance to the standard containers. With further study, solar disinfection in appropriate conditions may be included as a viable treatment option for wilderness water disinfection. Copyright © 2014 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  16. Formation of nitrogenous disinfection by-products in 10 chlorinated and chloraminated drinking water supply systems.

    Science.gov (United States)

    Liew, Deborah; Linge, Kathryn L; Joll, Cynthia A

    2016-09-01

    The presence of nitrogenous disinfection by-products (N-DBPs) in drinking water supplies is a public health concern, particularly since some N-DBPs have been reported to be more toxic than the regulated trihalomethanes and haloacetic acids. In this paper, a comprehensive evaluation of the presence of N-DBPs in 10 drinking water supply systems in Western Australia is presented. A suite of 28 N-DBPs, including N-nitrosamines, haloacetonitriles (HANs), haloacetamides (HAAms) and halonitromethanes (HNMs), were measured and evaluated for relationships with bulk parameters in the waters before disinfection. A number of N-DBPs were frequently detected in disinfected waters, although at generally low concentrations (water, N-DBP concentrations were significantly correlated with dissolved organic carbon (DOC) and ammonia, and these, in addition to high bromide in one of the waters, led to elevated concentrations of brominated HANs (26.6 μg/L of dibromoacetonitrile). There were significant differences in the occurrence of all classes of N-DBPs between chlorinated and chloraminated waters, except for HNMs, which were detected at relatively low concentrations in both water types. Trends observed in one large distribution system suggest that N-DBPs can continue to form or degrade within distribution systems, and redosing of disinfectant may cause further by-product formation.

  17. ANALYTICAL METHODS FOR WATER DISINFECTION BY-PRODUCTS IN FOODS AND BEVERAGES

    Science.gov (United States)

    The determination of exposure to drinking water disinfection byproducts (DBPs) requires an understanding of how drinking water comes in contact with humans through multiple pathways. In order to facilitate the investigation of human exposure to DBPs via foods and beverages, analy...

  18. Evaluation of Disinfection Byproducts formed from the Chlorination of Lyophilized and Reconstituted NOM Concentrate from a Drinking Water Source

    Science.gov (United States)

    Drinking water treatment and disinfection byproduct (DBP) research can be complicated by difficulties in shipping large water quantities and NOM geographical and temporal variability. Access to a drinking water representative, shelf-stable, concentrated NOM source would solve th...

  19. Evaluation of Disinfection Byproducts Formed from the Chlorination of Lyophilized and Reconstituted NOM Concentrate from a Drinking Water Source - Poster

    Science.gov (United States)

    Drinking water treatment and disinfection byproduct (DBP) research can be complicated by difficulties in shipping large water quantities and NOM geographical and temporal variability. Access to a drinking water representative, shelf-stable, concentrated NOM source would solve th...

  20. Solar water disinfection (SODIS): A review from bench-top to roof-top

    Energy Technology Data Exchange (ETDEWEB)

    McGuigan, Kevin G., E-mail: kmcguigan@rcsi.ie [Royal College of Surgeons in Ireland, Dublin 2 (Ireland); Conroy, Ronan M. [Royal College of Surgeons in Ireland, Dublin 2 (Ireland); Mosler, Hans-Joachim [EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133: CH-8600 Duebendorf (Switzerland); Preez, Martella du; Ubomba-Jaswa, Eunice [CSIR, Natural Resources and the Environment, Pretoria, Gauteng (South Africa); Fernandez-Ibanez, Pilar [Plataforma Solar de Almeria - CIEMAT, P.O. Box 22, 07200 Tabernas, Almeria (Spain)

    2012-10-15

    Graphical abstract: . Water being treated by solar disinfection outside a primary school classroom in Southern Uganda. Students fill their bottles at home and expose them to the sun while they are at school. Highlights: Black-Right-Pointing-Pointer A thorough review of current state of play of solar water disinfection. Black-Right-Pointing-Pointer An examination of both laboratory and field studies. Black-Right-Pointing-Pointer Description of the economic and behaviour change aspects of this technology. - Abstract: Solar water disinfection (SODIS) has been known for more than 30 years. The technique consists of placing water into transparent plastic or glass containers (normally 2 L PET beverage bottles) which are then exposed to the sun. Exposure times vary from 6 to 48 h depending on the intensity of sunlight and sensitivity of the pathogens. Its germicidal effect is based on the combined effect of thermal heating of solar light and UV radiation. It has been repeatedly shown to be effective for eliminating microbial pathogens and reduce diarrhoeal morbidity including cholera. Since 1980 much research has been carried out to investigate the mechanisms of solar radiation induced cell death in water and possible enhancement technologies to make it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking water with the solar disinfection (SODIS) technique. This review attempts to revise all relevant knowledge about solar disinfection from microbiological issues, laboratory research, solar testing, up to and including real application studies, limitations, factors influencing adoption of the technique and health impact.

  1. Seasonal evaluation of disinfection by-products throughout two full-scale drinking water treatment plants.

    Science.gov (United States)

    Zhong, Xin; Cui, Chongwei; Yu, Shuili

    2017-07-01

    Carbonyl compounds can occur alpha-hydrogens or beta-diketones substitution reactions with disinfectants contributed to halogenated by-products formation. The objective of this research was to study the occurrence and fate of carbonyl compounds as ozonation by-products at two full-scale drinking water treatment plants (DWTPs) using different disinfectants for one year. The quality of the raw water used in both plants was varied according to the season. The higher carbonyl compounds concentrations were found in raw water in spring. Up to 15 (as the sum of both DWTPs) of the 24 carbonyl compounds selected for this work were found after disinfection. The dominant carbonyl compounds were formaldehyde, glyoxal, methyl-glyoxal, fumaric, benzoic, protocatechuic and 3-hydroxybenzoic acid at both DWTPs. In the following steps in each treatment plant, the concentration patterns of these carbonyl compounds differed depending on the type of disinfectant applied. Benzaldehyde was the only aromatic aldehyde detected after oxidation with ozone in spring. As compared with DWTP 1, five new carbonyl compounds were formed (crotonaldehyde, benzaldehyde, formic, oxalic and malonic acid) disinfection by ozone, and the levels of the carbonyl compounds increased. In addition, pre-ozonation (PO) and main ozonation (OZ) increased the levels of carbonyl compounds, however coagulation/flocculation (CF), sand filtration (SF) and granular activated carbon filtration (GAC) decreased the levels of carbonyl compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Disinfection of drain water of tomato by means of UV radiation and slow sand filtration in real greenhouse circumstances.

    Science.gov (United States)

    De Rocker, E; Goen, K; Van Poucke, K

    2006-01-01

    The efficiency of the disinfection of drain water was tested at 11 greenhouses with tomato cultivation on rockwool substrate in Flanders (Belgium) by means of mycological analysis. In addition the presence of phytopathogenic fungi in the drain water was analysed at 2 supplementary greenhouses with recirculation without disinfection.

  3. Progressive Increase in Disinfection Byproducts and Mutagenicity from Sourceto Tap to Swimming Pool and Spa Water: Implications for Public Health

    Science.gov (United States)

    Pools and spas are enjoyed throughout the world for exercise and relaxation. However, there are no previous studies on the mutagenicity of disinfected spa (hot tub) waters or comprehensive identification of disinfection byproducts (DBPs) formed in spas. Using 28 water samples f...

  4. THE USE OF MODELS FOR GRANTING VARIANCES FROM MANDATORY DISINFECTION OF GROUND WATER USED AS A PUBLIC WATER SUPPLY

    Science.gov (United States)

    In November 1985, a Maximum Contaminant Level Goal of zero viruses in drinking water was published. By 1991, the U.S. Environmental Protection Agency Office of Drinking Water to promulgate regulations requiring that all ground water used for potable purposes disinfected prior to ...

  5. Efficiency in the disinfection of water for human consumption in rural communities using solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Dominguez, A. [Instituto de Investigaciones Electricas, Mor (Mexico); Alarcon-Herrera, M.T.; Martin-Dominguez, I.R. [Centtro de Investigacion en Materiales Avanzados, Chih (Mexico); Gonzalez-Herrera, A. [Instituto Mexicano de Tecnologia del Agua, Mor (Mexico)

    2005-01-01

    The efficiency of solar disinfection for the inactivation of Total Coliforms (TC) and Escherichia coli (EC) in drinking water was tested in rural communities of the Guachochi Municipality, in the Tarahumara Sierra, State of Chihuahua, Mexico. The study zone was selected mostly because it lacks formal water supply systems and the population is forced to consume untreated water directly from rivers and shallow or artesian wells without treatment. To determine the bacteriological quality of the water consumed by the population, the amount of TC and EC in the water supplies of 23 communities in the studied municipality was determined. The efficiency of the solar energy based water disinfection process was determined for several months of the humid and dry seasons with water from the most contaminated sources of the study zone. The performed tests consisted in studying the effect of disinfecting water by direct exposure to sunlight during the whole day, with and without solar concentrators, in plastic bottles of commercial beverages. The three types of bottles used were transparent, partially painted black (one half of the bottle, along the longitudinal axis), and totally black. The study shows that, in this geographic zone, the available water must be disinfected before consumption and disinfection efficiency can reach 100% through the use of solar radiation. It was found that, since more than 6 h of daily solar radiation are available during most of the year in this zone, no solar concentrators are really necessary to ensure the complete elimination of bacteria. A complete disinfection takes place by simply placing water bottles in the sunlight during the whole day. Nevertheless, the use of solar concentrators and bottles partially painted black increases the TC and EC inactivation efficiency, reducing the solar exposure time required for a total disinfection to just 2 h. With the use of solar concentrators and partially blackened bottles, the water temperature

  6. Point-of-use water disinfection using ultraviolet and visible light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lui, Gough Yumu, E-mail: gough@student.unsw.edu.au [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Roser, David, E-mail: djroser@unsw.edu.au [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Corkish, Richard, E-mail: r.corkish@unsw.edu.au [School of Photovoltaics and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Ashbolt, Nicholas J., E-mail: ashbolt@ualberta.ca [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); School of Public Health, South Academic Building, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); Stuetz, Richard, E-mail: r.stuetz@unsw.edu.au [UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2016-05-15

    Improvements in point-of-use (POU) drinking water disinfection technologies for remote and regional communities are urgently needed. Conceptually, UV-C light-emitting diodes (LEDs) overcome many drawbacks of low-pressure mercury tube based UV devices, and UV-A or visible light LEDs also show potential. To realistically evaluate the promise of LED disinfection, our study assessed the performance of a model 1.3 L reactor, similar in size to solar disinfection bottles. In all, 12 different commercial or semi-commercial LED arrays (270–740 nm) were compared for their ability to inactivate Escherichia coli K12 ATCC W3110 and Enterococcus faecalis ATCC 19433 over 6 h. Five log{sub 10} and greater reductions were consistently achieved using the 270, 365, 385 and 405 nm arrays. The output of the 310 nm array was insufficient for useful disinfection while 430 and 455 nm performance was marginal (≈ 4.2 and 2.3-log{sub 10}s E. coli and E. faecalis over the 6 h). No significant disinfection was observed with the 525, 590, 623, 660 and 740 nm arrays. Delays in log-phase inactivation of E. coli were observed, particularly with UV-A wavelengths. The radiation doses required for > 3-log{sub 10} reduction of E. coli and E. faecalis differed by 10 fold at 270 nm but only 1.5–2.5 fold at 365–455 nm. Action spectra, consistent with the literature, were observed with both indicators. The design process revealed cost and technical constraints pertaining to LED electrical efficiency, availability and lifetime. We concluded that POU LED disinfection using existing LED technology is already technically possible. UV-C LEDs offer speed and energy demand advantages, while UV-A/violet units are safer. Both approaches still require further costing and engineering development. Our study provides data needed for such work. - Highlights: • Disinfection of E. coli and E. faecalis achieved with 270 and 365–455 nm LEDs • No significant disinfection was found with 310 and > 455 nm LEDs

  7. Pipeline materials modify the effectiveness of disinfectants in drinking water distribution systems.

    Science.gov (United States)

    Lehtola, Markku J; Miettinen, Ilkka T; Lampola, Tiia; Hirvonen, Arja; Vartiainen, Terttu; Martikainen, Pertti J

    2005-05-01

    We studied how pipe material can modify the effectiveness of UV- and chlorine disinfection in drinking water and biofilms. This study was done with two pipe materials: copper and composite plastic (polyethylene, PE) in a pilot scale water distribution network. UV-disinfection decreased viable bacterial numbers in the pilot waterworks and outlet water of pipes on average by 79%, but in biofilms its disinfecting effect was minor. Chlorine decreased effectively the microbial numbers in water and biofilms of PE pipes. In outlet water from copper pipes, the effect of chlorination was weaker; microbial numbers increased back to the level before chlorination within a few days. In the biofilms present in the copper pipes, chlorine decreased microbial numbers only in front of the pipeline. One reason for weaker efficiency of chlorine in copper pipes was that its concentration declined more rapidly in the copper pipes than in the PE pipes. These results means that copper pipes may require a higher chlorine dosage than plastic pipes to achieve effective disinfection of the pipes.

  8. SOLAR WATER DISINFECTION IN NORTHEAST BRAZIL: KINETICS OF THE PROCESS AND THE STUDY FOR THE DEVELOPMENT OF A PILOT PLANT

    Directory of Open Access Journals (Sweden)

    LORNA FALCÃO FÉLIX

    2009-09-01

    Full Text Available An experimental and numerical study of decontamination efficiency was carried through to evaluate the application of solar energy in water treatment in Northeast Brazil. The methodology used was the one proposed by Solar Water Disinfection (SODIS. Contaminated water samples were collected at the community of Robalo, Sergipe State, Brazil, which is characterized by poverty, social exclusion and a high incidence of waterborne diseases. The method used for pre- and post-disinfection microbiological analyses was the Colilert® QuantiTray (IDEXX one. The results show that the efficiency of the disinfection process reached 80 to 100%, however a post-treatment increase in colony counts was observed in some samples. The experimental results were treated numerically, to give disinfection kinetics, thus allowing theoretical and experimental data to be compared. This study further presents considerations for the development of an experimental pilot plant for water disinfection using SODIS.

  9. Calibrating an optimal condition model for solar water disinfection in peri-urban household water treatment in Kampala, Uganda.

    Science.gov (United States)

    Okurut, Kenan; Wozei, Eleanor; Kulabako, Robinah; Nabasirye, Lillian; Kinobe, Joel

    2013-03-01

    In low income settlements where the quality of drinking water is highly contaminated due to poor hygienic practices at community and household levels, there is need for appropriate, simple, affordable and environmentally sustainable household water treatment technology. Solar water disinfection (SODIS) that utilizes both the thermal and ultra-violet effect of solar radiation to disinfect water can be used to treat small quantities of water at household level to improve its bacteriological quality for drinking purposes. This study investigated the efficacy of the SODIS treatment method in Uganda and determined the optimal condition for effective disinfection. Results of raw water samples from the study area showed deterioration in bacteriological quality of water moved from source to the household; from 3 to 36 cfu/100 mL for tap water and 75 to 126 cfu/100 mL for spring water, using thermotolerant coliforms (TTCs) as indicator microorganisms. SODIS experiments showed over 99.9% inactivation of TTCs in 6 h of exposure, with a threshold temperature of 39.5 ± 0.7°C at about 12:00 noon, in the sun during a clear sunny day. A mathematical optimal condition model for effective disinfection has been calibrated to predict the decline of the number of viable microorganisms over time.

  10. Solar water disinfection (SODIS): a review from bench-top to roof-top.

    Science.gov (United States)

    McGuigan, Kevin G; Conroy, Ronán M; Mosler, Hans-Joachim; du Preez, Martella; Ubomba-Jaswa, Eunice; Fernandez-Ibañez, Pilar

    2012-10-15

    Solar water disinfection (SODIS) has been known for more than 30 years. The technique consists of placing water into transparent plastic or glass containers (normally 2L PET beverage bottles) which are then exposed to the sun. Exposure times vary from 6 to depending on the intensity of sunlight and sensitivity of the pathogens. Its germicidal effect is based on the combined effect of thermal heating of solar light and UV radiation. It has been repeatedly shown to be effective for eliminating microbial pathogens and reduce diarrhoeal morbidity including cholera. Since 1980 much research has been carried out to investigate the mechanisms of solar radiation induced cell death in water and possible enhancement technologies to make it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking water with the solar disinfection (SODIS) technique. This review attempts to revise all relevant knowledge about solar disinfection from microbiological issues, laboratory research, solar testing, up to and including real application studies, limitations, factors influencing adoption of the technique and health impact. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Trihalomethanes in chlorine and bromine disinfected swimming pools: air-water distributions and human exposure.

    Science.gov (United States)

    Lourencetti, Carolina; Grimalt, Joan O; Marco, Esther; Fernandez, Pilar; Font-Ribera, Laia; Villanueva, Cristina M; Kogevinas, Manolis

    2012-09-15

    This first study of trihalomethanes (THMs) in swimming pools using bromine agents for water disinfection under real conditions shows that the mixtures of these compounds are largely dominated by bromoform in a similar process as chloroform becomes the dominant THM in pools disinfected with chlorine agents. Bromoform largely predominates in air and water of the pool installations whose concentration changes are linearly correlated. However, the air concentrations of bromoform account for about 6-11% of the expected concentrations according to theoretical partitioning defined by the Henry law. Bromoform in exhaled air of swimmers is correlated with the air concentrations of this disinfectant by-product in the pool building. Comparison of the THM exhaled air concentrations between swimmers and volunteers bathing in the water without swimming or standing in the building outside the water suggest that physical activity enhance exposure to these disinfectant by-products. They also indicate that in swimming pools, besides inhalation, dermal absorption is a relevant route for the incorporation of THMs, particularly those with lower degree of bromination. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. ANIMAL MODELS FOR STUDYING MISCARRIAGE: ILLUSTRATION WITH STUDY OF DRINKING WATER DISINFECTION BY-PRODUCTS

    Science.gov (United States)

    Animal models for studying miscarriage: Illustration with study of drinking water disinfection by-productsAuthors & affiliations:Narotsky1, M.G. and S. Bielmeier Laffan2.1Reproductive Toxicology Division, NHEERL, ORD, U.S. Environmental Protection Agency, Research Tri...

  13. Community challenges when using large plastic bottles for Solar Energy Disinfection of Water (SODIS)

    National Research Council Canada - National Science Library

    Borde, Preeti; Elmusharaf, Khalifa; McGuigan, Kevin G; Keogh, Michael B

    2016-01-01

    ... disinfection (SODIS) is a simple and cheap method which uses natural sunlight to treat contaminated water filled into transparent plastic containers and exposed to direct sunlight for up to 6 h. SODIS has conventionally been implemented using 1-2 L polyethylene terephthalate (PET) bottles which have shown good characteristics of microbiological ina...

  14. AN INTEGRATED RESEARCH AGENDA TO EVALUATE TAP WATER DISINFECTION BYPRODUCTS AND HUMAN HEALTH: PART 1

    Science.gov (United States)

    An Integrated Research Agenda to Evaluate Tap Water Disinfection Byproducts and Human Health: Part I Michele Lynberg1, David Ashley 2, Pauline Mendola3, J. R. Nuckols4, Kenneth Cantor5, Benjamin Blount 2, Philip Singer6, Charles Wilkes7, Lorraine Backer1, and Peter Langlo...

  15. Influence of solar water disinfection on immunity against cholera: a review

    CSIR Research Space (South Africa)

    Ssemakalu, CC

    2014-09-01

    Full Text Available on the spread of waterborne diseases 115 The consumption of SODIS water in sub-Saharan African and various East Asian countries 116 has reduced the percentage of individuals acquiring water borne diseases such as dysentery 117 typhoid and cholera (Conroy, et... review, the possible influence that solar water disinfection may have on the immunity 35 against cholera is discussed. 36 Keywords: Cholera, SODIS, Solar Ultraviolet Radiation, Vaccine, V. cholerae, Waterborne 37 disease 38 39 40 3...

  16. Efficacy of Various Chemical Disinfectants on Biofilms Formed in Spacecraft Potable Water System Component

    Science.gov (United States)

    Wong, Willy; Garcia, Veronica; Castro, Victoria; Ott, Mark; Duane

    2009-01-01

    As the provision of potable water is critical for successful habitation of the International Space Station (ISS), life support systems were installed in December 2008 to recycle both humidity from the atmosphere and urine to conserve available water in the vehicle. Pre-consumption testing from the dispensing needle at the Potable Water Dispenser (PWD) indicated that bacterial concentrations exceeded the current ISS specifications of 50 colony forming units (CFU) per ml. Subsequent investigations revealed that a corrugated stainless steel flex hose upstream of the dispensing needle in the PWD was filled with non-sterile water and left at room temperature for over one month before launch. To simulate biofilm formation that was suspected in the flight system, sterile flex hoses were seeded with a consortium of bacterial isolates previously recovered from other ISS water systems, which included Ralstonia pickettii, Burkholderia multivorans, Caulobacter vibrioides., and Cupriavidus pauculus. After 5 days of incubation, these hoses were challenged with various chemical disinfectants including hydrogen peroxide, colloidal silver, and buffered pH solutions to determine the ability of the disinfectants to decrease and maintain bacterial concentrations below ISS specifications. Disinfection efficacy over time was measured by collecting daily heterotrophic plate counts following exposure to the disinfectants. A single flush with either 6% hydrogen peroxide solution or a mixture of 3% hydrogen peroxide and 400 ppb colloidal silver effectively reduced the bacterial concentrations to less than 1 CFU/ml for a period of up to 2 months. Testing results indicated that hydrogen peroxide and mixtures of hydrogen peroxide and colloidal silver have tremendous potential as alternative disinfectants for ISS water systems.

  17. Evaluation of Filtration and UV Disinfection for Inactivation of Viruses in Non-Community Water Systems in Minnesota

    Science.gov (United States)

    This study evaluated filtration and disinfection processes for removal and inactivation of pathogens in non-community water systems (NCWS) in two surface water supplies. Pretreatment systems included 1) pressure sand filtration, and 2) granular activated carbon adsorption, and 3...

  18. Development of a research strategy for integrated technology-based toxicological and chemical evaluation of complex mixtures of drinking water disinfection byproducts.

    OpenAIRE

    Simmons, Jane Ellen; Richardson, Susan D.; Speth, Thomas F; Miltner, Richard J; Rice, Glenn; Schenck, Kathleen M; Hunter, E Sidney; Teuschler, Linda K.

    2002-01-01

    Chemical disinfection of water is a major public health triumph of the 20th century. Dramatic decreases in both morbidity and mortality of waterborne diseases are a direct result of water disinfection. With these important public health benefits comes low-level, chronic exposure to a very large number of disinfection byproducts (DBPs), chemicals formed through reaction of the chemical disinfectant with naturally occurring inorganic and organic material in the source water. This article provid...

  19. Modelling of Disinfection by-products formation via UV irradiation of the water from Tajan River (source water for Sari drinking water, Iran)

    OpenAIRE

    Allahbakhsh Javid; Aliakbar Roudbari; Ahmad Reza Yari

    2013-01-01

    Background & Aims of the Study Irradiation with ultraviolet light (UV) is used for the disinfection of bacterial contaminants in the production of potable water. The main objective of the study was to investigate and model Disinfection By-Products (DBPs) formation due to the UV Irradiation of the Tajan River water under different Irradiation conditions. Materials & Methods:  Water samples were collected throughout September 2011 to August 2013. Transportation of the sampl...

  20. Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures.

    Science.gov (United States)

    Marchesi, Isabella; Ferranti, Greta; Mansi, Antonella; Marcelloni, Anna M; Proietto, Anna R; Saini, Navneet; Borella, Paola; Bargellini, Annalisa

    2016-05-15

    Physical and chemical disinfection methods have been proposed with the aim of controlling Legionella water contamination. To date, the most effective procedures for reducing bacterial contamination have not yet been defined. The aim of this study was to assess the long-term effectiveness of various disinfection procedures in order to reduce both culturable and nonculturable (NC) legionellae in different hospital water networks treated with heat, chlorine dioxide, monochloramine, and hydrogen peroxide. The temperature levels and biocide concentrations that proved to give reliable results were analyzed. In order to study the possible effects on the water pipes, we verified the extent of corrosion on experimental coupons after applying each method for 6 months. The percentage of positive points was at its lowest after treatment with monochloramine, followed by chlorine dioxide, hydrogen peroxide, and hyperthermia. Different selections of Legionella spp. were observed, as networks treated with chlorine-based disinfectants were contaminated mainly by Legionella pneumophila serogroup 1, hyperthermia was associated with serogroups 2 to 14, and hydrogen peroxide treatment was associated mainly with non-pneumophila species. NC cells were detected only in heat-treated waters, and also when the temperature was approximately 60°C. The corrosion rates of the coupons were within a satisfactory limit for water networks, but the morphologies differed. We confirm here that chemical disinfection controls Legionella colonization more effectively than hyperthermia does. Monochloramine was the most effective treatment, while hydrogen peroxide may be a promising alternative to chlorine-based disinfectants due to its ability to select for other, less virulent or nonpathogenic species. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  1. Safety and durability of low-density polyethylene bags in solar water disinfection applications.

    Science.gov (United States)

    Danwittayakul, Supamas; Songngam, Supachai; Fhulua, Tipawan; Muangkasem, Panida; Sukkasi, Sittha

    2017-08-01

    Solar water disinfection (SODIS) is a simple point-of-use process that uses sunlight to disinfect water for drinking. Polyethylene terephthalate (PET) bottles are typically used as water containers for SODIS, but a new SODIS container design has recently been developed with low-density polyethylene (LDPE) bags and can overcome the drawbacks of PET bottles. Two nesting layers of LDPE bags are used in the new design: the inner layer containing the water to be disinfected and the outer one creating air insulation to minimize heat loss from the water to the surroundings. This work investigated the degradation of LDPE bags used in the new design in actual SODIS conditions over a period of 12 weeks. The degradation of the LDPE bags was investigated weekly using a scanning electron microscope, Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometer, and tensile strength tester. It was found that the LDPE bags gradually degraded under the sunlight due to photo-oxidation reactions, especially in the outer bags, which were directly exposed to the sun and surroundings, leading to the reduction of light transmittance (by 11% at 300 nm) and tensile strength (by 33%). In addition, possible leaching of organic compounds into the water contained in the inner bags was examined using gas chromatography-mass spectrometer. 2,4-Di-tert-butylphenol was found in some SODIS water samples as well as the as-received water samples, in the concentration range of 1-4 μg/L, which passes the Environmental Protection Agency Drinking Water Guidance on Disinfection By-Products.

  2. Trihalomethane formation during water disinfection in four water supplies in the Somes river basin in Romania.

    Science.gov (United States)

    Ristoiu, Dumitru; von Gunten, Urs; Mocan, Aurel; Chira, Romeo; Siegfried, Barbara; Haydee Kovacs, Melinda; Vancea, Sidonia

    2009-08-01

    After the discovery of chloroform in drinking water, an extensive amount of work has been dedicated to the factors influencing the formation of halogenated disinfections by-products (DBPs). The disinfection practice can vary significantly from one country to another. Whereas no disinfectant is added to many water supplies in Switzerland or no disinfectant residual is maintained in the distribution system, high disinfectant doses are applied together with high residual concentrations in the distribution system in other countries such as the USA or some southern European countries and Romania. In the present study, several treatment plants in the Somes river basin in Romania were investigated with regard to chlorine practice and DBP formation (trihalomethanes (THMs)). Laboratory kinetic studies were also performed to investigate whether there is a relationship between raw water dissolved organic matter, residual chlorine, water temperature and THM formation. Drinking water samples were collected from different sampling points in the water treatment plant (WTP) from Gilau and the corresponding distribution system in Cluj-Napoca and also from Beclean, Dej and Jibou WTPs. The water samples were collected once a month from July 2006 to November 2007 and stored in 40-mL vials closed with Teflon lined screw caps. Water samples were preserved at 4 degrees C until analysis after sodium thiosulfate (Na(2)S(2)O(3)) had been added to quench residual chlorine. All samples were analysed for THMs using headspace GC-ECD between 1 and 7 days after sampling. The sample (10 mL) was filled into 20-mL headspace vials and closed with a Teflon-lined screw cap. Thereafter, the samples were equilibrated in an oven at 60 degrees C for 45 min. The headspace (1 mL) was then injected into the GC (Cyanopropylphenyl Polysiloxane column, 30 m x 53 mm, 3 microm film thickness, Thermo Finnigan, USA). The MDLs for THMs were determined from the standard deviation of eight standards at 1 microg/L. The

  3. Do Iodine Contrast Media Compounds Used for Medical Imaging Contribute to the Formation of Iodinated Disinfection By-Products in Drinking Water?

    Science.gov (United States)

    Iodinated disinfection byproducts (DBPs) have recently gained attention due to their cyto- and genotoxicity and increased formation in drinking water treated with chloramine, which has become an increasingly popular disinfectant in the United States. One of these—iodoacetic acid...

  4. BLANKET REPRESENTATION AND EXPEDIENT OF DISINFECTING WATER USING PULSING ELECTROMAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    Ibragimova Ozoda

    2013-11-01

    Full Text Available ABSTRACT:  The paper deals with comparative analysis of existing expedients and devices of disinfecting water, spots ways of the solution and a new method of  water purification using electromagnetic field applied in a cross wise direction. ABSTRAK: Dalam operasi, analisis perbandingan dijalankan bagi menentukan  kesesuaian yang sedia ada dan alatan untuk menyahjangkit air. Dengan mengaplikasikan medan magnet lintang, penyelesaian masalah dikenal pasti dengan meningkatkan kemagnetan terhadap medan elektromagnet ke atas air.

  5. Factors associated with compliance among users of solar water disinfection in rural Bolivia

    OpenAIRE

    Christen, Andri; Duran Pacheco, Gonzalo; Hattendorf, Jan; Arnold, Benjamin F; Cevallos, Myriam; Indergand, Stefan; Colford, John M; Mäusezahl, Daniel

    2011-01-01

    Abstract Background Diarrhoea is the second leading cause of childhood mortality, with an estimated 1.3 million deaths per year. Promotion of Solar Water Disinfection (SODIS) has been suggested as a strategy for reducing the global burden of diarrhoea by improving the microbiological quality of drinking water. Despite increasing support for the large-scale dissemination of SODIS, there are few reports describing the effectiveness of its implementation. It is, therefore, important to identify ...

  6. Solar disinfection: an approach for low-cost household water treatment technology in Southwestern Ethiopia.

    Science.gov (United States)

    Dessie, Awrajaw; Alemayehu, Esayas; Mekonen, Seblework; Legesse, Worku; Kloos, Helmut; Ambelu, Argaw

    2014-01-10

    Disinfection of contaminated water using solar radiation (SODIS) is known to inactivate bacteria. Its inactivation efficiency depends on local conditions where the disinfection is made. This study was aiming to test the efficiency of solar disinfection using different water parameters as low-cost household water treatment technology. Inactivation of microbes was tested using fecal coliform as test organism. The SODIS experiment was carried out at turbidity 2NTU, pH 7, and various water temperature (38.1°C, 41.8°C, 45.6°Cand 51.1°C) and solar intensities, using clear and black plastic bottles filled to different depths. The results show that the rate of microbial inactivation in relation to depth of water, turbidity, container type, intensity of light and color of container was statistically significant (p SODIS could play a significant role in the provision of safe water in rural communities of developing countries where there is ample sunshine, specifically in sub-Saharan African countries.

  7. Biological efficacy and toxic effect of emergency water disinfection process based on advanced oxidation technology.

    Science.gov (United States)

    Tian, Yiping; Yuan, Xiaoli; Xu, Shujing; Li, Rihong; Zhou, Xinying; Zhang, Zhitao

    2015-12-01

    An innovative and removable water treatment system consisted of strong electric field discharge and hydrodynamic cavitation based on advanced oxidation technologies was developed for reactive free radicals producing and waterborne pathogens eliminating in the present study. The biological efficacy and toxic effects of this advanced oxidation system were evaluated during water disinfection treatments. Bench tests were carried out with synthetic microbial-contaminated water, as well as source water in rainy season from a reservoir of Dalian city (Liaoning Province, China). Results showed that high inactivation efficiency of Escherichia coli (>5 log) could be obtained for synthetic contaminated water at a low concentration (0.5-0.7 mg L(-1)) of total oxidants in 3-10 s. The numbers of wild total bacteria (108 × 10(3) CFU mL(-1)) and total coliforms (260 × 10(2) MPN 100 mL(-1)) in source water greatly reduced to 50 and 0 CFU mL(-1) respectively after treated by the advanced oxidation system, which meet the microbiological standards of drinking water, and especially that the inactivation efficiency of total coliforms could reach 100%. Meanwhile, source water qualities were greatly improved during the disinfection processes. The values of UV254 in particular were significantly reduced (60-80%) by reactive free radicals. Moreover, the concentrations of possible disinfection by-products (formaldehyde and bromide) in treated water were lower than detection limits, indicating that there was no harmful effect on water after the treatments. These investigations are helpful for the ecotoxicological studies of advanced oxidation system in the treatments of chemical polluted water or waste water. The findings of this work suggest that the developed water treatment system is ideal in the acute phases of emergencies, which also could offer additional advantages over a wide range of applications in water pollution control.

  8. Advanced Oxidation Technology for Potable Water Disinfection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The availability of high-quality potable water is essential in crewed space missions. Closed loop water recycling systems as well as potable water holding tanks and...

  9. [Microbial contamination of wash water in automatic washing and disinfection machines].

    Science.gov (United States)

    Kolch, A; Krizek, L; Schoenen, D

    1993-11-01

    Samples were taken from the water containing tube system of 7 cleaning and disinfection machines located at the university clinics. The machines were used for the treatment of medical tools. The samples were bacteriologically examined. The results showed systemic contaminations of the tubes of all tested machines. The well known positive effect of common ion-exchangers on bacterial growth was not the only reason for the high degree of microbial contaminations. Partial bacterial growth on the inner sides of the water tubes was detected. The reason was the use of bacteriological objectionable tube materials. Recontamination of the post treated medical tools is possible at any time by the last washing water. Preceding sterile filtration showed as supposed no effect. Consequences for the use of cleaning and disinfection machines are discussed.

  10. Effect of disinfectant, water age, and pipe materials on bacterial and eukaryotic community structure in drinking water biofilm.

    Science.gov (United States)

    Wang, Hong; Masters, Sheldon; Edwards, Marc A; Falkinham, Joseph O; Pruden, Amy

    2014-01-01

    Availability of safe, pathogen-free drinking water is vital to public health; however, it is impossible to deliver sterile drinking water to consumers. Recent microbiome research is bringing new understanding to the true extent and diversity of microbes that inhabit water distribution systems. The purpose of this study was to determine how water chemistry in main distribution lines shape the microbiome in drinking water biofilms and to explore potential associations between opportunistic pathogens and indigenous drinking water microbes. Effects of disinfectant (chloramines, chlorine), water age (2.3 days, 5.7 days), and pipe material (cement, iron, PVC) were compared in parallel triplicate simulated water distribution systems. Pyrosequencing was employed to characterize bacteria and terminal restriction fragment polymorphism was used to profile both bacteria and eukaryotes inhabiting pipe biofilms. Disinfectant and water age were both observed to be strong factors in shaping bacterial and eukaryotic community structures. Pipe material only influenced the bacterial community structure (ANOSIM test, P water age on both bacteria and eukaryotes were noted. Disinfectant concentration had the strongest effect on bacteria, while dissolved oxygen appeared to be a major driver for eukaryotes (BEST test). Several correlations of similarity metrics among populations of bacteria, eukaryotes, and opportunistic pathogens, as well as one significant association between mycobacterial and proteobacterial operational taxonomic units, provides insight into means by which manipulating the microbiome may lead to new avenues for limiting the growth of opportunistic pathogens (e.g., Legionella) or other nuisance organisms (e.g., nitrifiers).

  11. [Combined use of active chlorine and coagulants for drinking water purification and disinfection].

    Science.gov (United States)

    Rakhmanin, Iu A; Zholdakova, Z I; Poliakova, E E; Kir'ianova, L F; Miasnikov, I N; Tul'skaia, E A; Artemova, T Z; Ivanova, L V; Dmitrieva, R A; Doskina, T V

    2004-01-01

    The authors made an experimental study of the efficiency of water purification procedures based on the combined use of active chlorine and coagulants and hygienically evaluated the procedures. The study included the evaluation of water disinfection with various coagulants and active chlorine; the investigation of the processes of production of deleterious organic chlorine compounds; the assessment of the quality of water after its treatment. The coagulants representing aluminum polyoxychloride: RAX-10 (AQUA-AURATE 10) and RAX-18 (AQUA-AURATE 18), and aluminum sulfate, technically pure grade were tested. The treatment of river water with the coagulants RAX-10 and RAX-18, followed by precipitation, filtration, and chlorination under laboratory conditions, was shown to result in water disinfection to the levels complying with the requirements described in SanPiN 2.1.4.1074-01. RAX-18 showed the best disinfecting activity against total and heat-tolerant coliform bacteria, but also to the highly chlorine-resistant microrganisms--the spores of sulfite-reducing Clostridia, phages, and viruses. Since the coagulants have an increased sorptive capacity relative to humus and other organic substances, substitution of primary chlorination for coagulant treatment may induce a reduction in the risk of formation of oncogenically and mutagenically hazardous chlorinated hydrocarbons.

  12. Drinking water quality and solar disinfection: effectiveness in peri-urban households in Nepal.

    Science.gov (United States)

    Rainey, Rochelle C; Harding, Anna K

    2005-09-01

    The study examined pH, turbidity and fecal contamination of drinking water from household water storage containers, wells and taps, and the Godawari River, and tested the effectiveness of solar disinfection (SODIS) in reducing levels of fecal contamination from household containers. The research was conducted in 40 households in a village 6 km outside the capital city of Kathmandu, Nepal. Three rounds of data were collected: a baseline in March 2002 followed by training in solar disinfection, and follow-ups in June and July 2002. Untreated drinking water was found to have levels of contamination ranging from 0 to too numerous to count fecal coliform CFU 100ml(-1). Source water was significantly more contaminated than water from the household storage containers. Wells were less contaminated than taps. SODIS reduced the level of contamination under household conditions. Turbidity from taps was above 30 NTU in the rainy season, above the maximum for effective solar disinfection. SODIS was routinely adopted by only 10% of the participating households during the study.

  13. Influence of solar water disinfection on immunity against cholera - a review.

    Science.gov (United States)

    Ssemakalu, Cornelius Cano; Ubomba-Jaswa, Eunice; Motaung, Keolebogile Shirley; Pillay, Michael

    2014-09-01

    Cholera remains a problem in developing countries. This is attributed to the unavailability of proper water treatment, sanitary infrastructure and poor hygiene. As a consequence, countries facing cholera outbreaks rely on interventions such as the use of oral rehydration therapy and antibiotics to save lives. In addition to vaccination, the provision of chlorine tablets and hygiene sensitization drives have been used to prevent new cholera infections. The implementation of these interventions remains a challenge due to constraints associated with the cost, ease of use and technical knowhow. These challenges have been reduced through the use of solar water disinfection (SODIS). The success of SODIS in mitigating the risk associated with the consumption of waterborne pathogens has been associated with solar irradiation. This has prompted a lot of focus on the solar component for enhanced disinfection. However, the role played by the host immune system following the consumption of solar-irradiated water pathogens has not received any significant attention. The mode of inactivation resulting from the exposure of microbiologically contaminated water results in immunologically important microbial states as well as components. In this review, the possible influence that solar water disinfection may have on the immunity against cholera is discussed.

  14. Disinfection of Spacecraft Potable Water Systems by Photocatalytic Oxidation Using UV-A Light Emitting Diodes

    Science.gov (United States)

    Birmele, Michele N.; O'Neal, Jeremy A.; Roberts, Michael S.

    2011-01-01

    Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in <180 minutes of contact

  15. Experience in using thermal disinfection to remove viable bacteria and endotoxins in centraly distributed reverse osmosis water.

    Science.gov (United States)

    Alayoud, Ahmed; Hamzi, Mohamed Amine; Razkaoui, Abdelaziz; Benyahia, Mohammed

    2014-01-01

    The water used for dilution of hemodialysis concentrates has to meet official quality recommendations regarding microbiology and chemical parameters. To avoid chemical use and to simplify treatments, hot water has been used to control microbial contamination of water distribution systems. In this study we evaluated the efficacy of heat disinfection in maintaining the quality of dialysis water generated by reverse osmosis (RO). During the first part of the study, we consecutively used (1) continuous water circulation, (2) daily heat disinfection and (3) a combination of daily heat disinfection and weekly chemical disinfection while checking bacterial count and endotoxin level every 4-5 weeks. During the second part of the study, we continued using daily heat disinfection while checking bacterial count and endotoxin level on weekly basis. The endotoxin levels at all sampling points of the water treatment system were lower than 0.005/ ml throughout the study. The application of heat disinfection alone reduced bacterial levels but an escape phenomenon occurred. After an interval of 21 days, an exponential increase of bacterial count was noted and cultures from the RO unit revealed growth of Pseudomonas fluorescence. The addition of chemical disinfection was successful in eliminating micro-organisms. Throughout this study, micro-organisms and endotoxins were not detectable in dialysate fluid and substitution fluid in dialysis monitors. The isolation of a thermo-sensitive organism from the RO unit after a period of relying on thermal disinfection suggests the existence of dead space in the RO unit that is not adequately exposed to heat but is accessible to chemical disinfection. .

  16. Water disinfection using photo-Fenton: Effect of temperature on Enterococcus faecalis survival.

    Science.gov (United States)

    Ortega-Gómez, E; Fernández-Ibáñez, P; Ballesteros Martín, M M; Polo-López, M I; Esteban García, B; Sánchez Pérez, J A

    2012-11-15

    The photo-Fenton process is a promising alternative to classical water disinfection treatments, although information in this regard is scarce due to its operational limitations. The effect of temperature (10, 20, 30 and 40 °C) was studied on water disinfection using the photo-Fenton reaction at initial near neutral pH with resorcinol as a model of natural organic matter (NOM). Enterococcus faecalis, a Gram-positive microorganism, was selected as an indicator of wastewater faecal contamination. The individual effects of different variables involved in this process (mechanical stress, UVA, H(2)O(2), Fe(2+), H(2)O(2)/Fe(2+), UVA/Fe(2+), UVA/H(2)O(2) and UVA/H(2)O(2)/Fe(2+)) were determined. UVA and H(2)O(2) led to a 2.5-log decrease individually and the combined effect of both variables managed to disinfect up to the detection limit (i.e. from a 5.5 to a 6-log reduction) over the same treatment time. Only by adding 10 mg L(-1) of Fe(2+), the inactivation time was reduced from 120 min (H(2)O(2)/UVA) to 80 min (H(2)O(2)/UVA/Fe(2+); photo-Fenton) with 120 mg L(-1) of H(2)O(2). A higher disinfection result for E. faecalis was observed by increasing temperature according to the Arrhenius equation in the photo-Fenton process. The detection limit was not reached at 10 °C and, to achieve the detection limit at 20, 30 and 40 °C, 80, 65 and 40 min were needed, respectively. The decrease in treatment time is a key factor in applying the photo-Fenton disinfection process to a wastewater treatment plant. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Acceptability of solar disinfection of drinking water treatment in Kathmandu Valley, Nepal.

    Science.gov (United States)

    Rainey, Rochelle C; Harding, Anna K

    2005-10-01

    This research examines the acceptability of solar disinfection of drinking water (SODIS) in a village in Kathmandu Valley, Nepal, using constructs from the Health Belief Model as a framework to identify local understandings of water, sanitation and health issues. There has been no published research on the acceptability of SODIS in household testing in Nepal. Understanding the context of water and water purity in Nepalese villages is essential to identify culturally appropriate interventions to improve the quality of drinking water and health. Forty households from the village census list were randomly selected and the senior woman in each household was asked to participate. Baseline data on water sources and behaviors were collected in March 2002, followed by training in SODIS. Follow-up data were collected in June and July 2002. Only 9% of households routinely adopted SODIS. Participants mentioned the benefit of treating water to reduce stomach ailments, but this did not outweigh the perceived barriers of heavy domestic and agricultural workloads, other cultural barriers, uncertainty about the necessity of treating the water, and lack of knowledge that untreated drinking water causes diarrhea. Strategies for developing safe water systems must include public health education about waterborne diseases, source water protection, and a motivational component to achieve implementation and sustained use. In addition, other options for disinfecting water should be provided, given the women's work constraints and low level of formal education.

  18. Efficient Disinfection of Tap and Surface Water with Single High Power 285 nm LED and Square Quartz Tube

    Directory of Open Access Journals (Sweden)

    Martin Hessling

    2016-01-01

    Full Text Available A small water disinfection system based on the combination of a strong single 25 mW LED with a wavelength of 285 nm and a short quartz tube with an outer rectangular cross section is presented. For the disinfection tests clear tap water and slightly turbid and yellow pond water are contaminated with high concentrations of Escherichia coli bacteria. These water samples are exposed to the germicidal 285 nm LED radiation while they flow through the quartz tube. The portion of surviving germs is determined by membrane filtration for different water qualities and flow rates. For clear tap water the bacteria concentration can be reduced by at least three orders of magnitude up to flow rates of about 20 L/h. In pond water the maximum flow rate for such a reduction is less than 3 L/h. These high disinfection capabilities and the small size of this system, allow its integration in medical systems for point of use disinfection or even its application in the Third World for decentralized water disinfection powered by small solar cells, because this disinfection capacity should be sufficient for small groups or families.

  19. Evaluation of thirteen haloacetic acids and ten trihalomethanes formation by peracetic acid and chlorine drinking water disinfection.

    Science.gov (United States)

    Xue, Runmiao; Shi, Honglan; Ma, Yinfa; Yang, John; Hua, Bin; Inniss, Enos C; Adams, Craig D; Eichholz, Todd

    2017-12-01

    Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs. Iodo-HAAs and iodo-THMs (I-HAAs and I-THMs) are formed during the disinfection of the water containing high levels of iodide and are much more toxic than their chlorinated and brominated analogs. Peracetic acid (PAA) is a strong antimicrobial disinfectant that is expected to reduce the formation of HAAs and THMs during disinfection. In this study, the formations of thirteen HAAs and ten THMs, including the iodinated forms, have been investigated during PAA disinfection and chlorination as the comparison. The DBP formations under different iodide concentrations, pHs, and contact times were systematically investigated. Two types of commercial PAAs containing different concentrations of PAA and hydrogen peroxide (H 2 O 2 ) were studied. A solid-phase microextraction gas chromatography-mass spectrometry method was upgraded for THM analysis including I-THMs. HAAs were analyzed by following a recently developed high performance ion chromatography-tandem mass spectrometry method. Results show that the ratio of PAA and H 2 O 2 concentration significantly affect the formation of I-THMs and I-HAAs. During PAA disinfection with lower PAA than H 2 O 2 , no detectable levels of THMs and HAAs were observed. During PAA disinfection with higher PAA than H 2 O 2 , low levels of monoiodoacetic acid, diiodoacetic acid, and iodoform were formed, and these levels were enhanced with the increase of iodide concentration. No significant quantities of chloro- or bromo-THMs and HAAs were formed during PAA disinfection treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Electrochemically activated water as an alternative to chlorine for decentralized disinfection

    KAUST Repository

    Ghebremichael, Kebreab A.

    2011-06-01

    Electrochemically activated (ECA) water is being extensively studied and considered as an alternative to chlorine for disinfection. Some researchers claim that ECA is by and large a chlorine solution, while others claim the presence of reactive oxygen species such as ozone and hydroxyl radicals in addition to chlorine. This study compares sodium hypochlorite (NaOCl) and ECA in terms of disinfection efficacy, trihalomethanes (THMs) formation, stability and composition. The studies were carried out under different process conditions (pH 5,7 and 9, disinfectant concentrations of 2-5 mg/L and dissolved organic carbon (DOC) concentration of 2-4 mg/L). The results indicated that in the presence of low DOC (<2 mg/L) ECA showed better disinfection efficacy for Escherichia coli inactivation, formed lower THM and had better stability compared with NaOCl at both pH 5 and 7. Stability studies of stock solutions showed that over a period of 30 days, ECA decayed by only 5% while NaOCl decayed by 37.5% at temperatures of 4 °C. In a fresh ECA of 200 mg/L chlorine, about 5.3 mg/L ozone and 36.9 mg/L ClO2 were detected. The study demonstrates that ECA could be a suitable alternative to NaOCl where decentralized production and use are required. © IWA Publishing 2011.

  1. Selective Photocatalytic Disinfection by Coupling StrepMiniSog to the Antibody Catalyzed Water Oxidation Pathway.

    Directory of Open Access Journals (Sweden)

    Elizabeth M Wurtzler

    Full Text Available For several decades reactive oxygen species have been applied to water quality engineering and efficient disinfection strategies; however, these methods are limited by disinfection byproduct and catalyst-derived toxicity concerns which could be improved by selectively targeting contaminants of interest. Here we present a targeted photocatalytic system based on the fusion protein StrepMiniSOG that uses light within the visible spectrum to produce reactive oxygen species at a greater efficiency than current photosensitizers, allowing for shorter irradiation times from a fully biodegradable photocatalyst. The StrepMiniSOG photodisinfection system is unable to cross cell membranes and like other consumed proteins, can be degraded by endogenous digestive enzymes in the human gut, thereby reducing the consumption risks typically associated with other disinfection agents. We demonstrate specific, multi-log removal of Listeria monocytogenes from a mixed population of bacteria, establishing the StrepMiniSOG disinfection system as a valuable tool for targeted pathogen removal, while maintaining existing microbial biodiversity.

  2. Nano-silver in drinking water and drinking water sources: stability and influences on disinfection by-product formation.

    Science.gov (United States)

    Tugulea, A-M; Bérubé, D; Giddings, M; Lemieux, F; Hnatiw, J; Priem, J; Avramescu, M-L

    2014-10-01

    Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag(+) ions (as AgNO3). The stability of the nano-silver dispersions in

  3. Disinfection Byproduct Formation in Reverse-Osmosis Concentrated and Lyophilized Natural Organic Matter from a Drinking Water Source

    Science.gov (United States)

    Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking wa...

  4. Estimated Effects of Disinfection By-Products on Preterm Birth in a Population Served by a Single Water Utility

    National Research Council Canada - National Science Library

    Chad Lewis; Irwin H. Suffet; Katherine Hoggatt; Beate Ritz

    Objectives: We evaluated the association between drinking-water disinfection by-products and preterm births using improved exposure assessment and more appropriate analysis methods than used in prior studies. Methods...

  5. Synthesis and characterization of alginate beads encapsulated zinc oxide nanoparticles for bacteria disinfection in water.

    Science.gov (United States)

    Motshekga, Sarah Constance; Sinha Ray, Suprakas; Maity, Arjun

    2017-11-03

    The use of polymer nanocomposites as novel materials for water remediation has emerged as a promising alternative for disinfection of bacteria contaminated water. Sodium alginate, a natural biopolymer has been investigated in this study by encapsulating antimicrobial zinc oxide nanoparticles supported bentonite. The confirmation of the alginate nanocomposites was done by use of TEM, SEM-EDS and XRD. The antimicrobial activity of the alginate nanocomposites was investigated by batch studies using surface water and synthetic bacteria contaminated water containing Staphylococcus aureus. The effect of nanocomposite amount and initial bacteria concentration has been studied. The inactivation results indicated that the nanocomposite effectively inactivated bacteria in both the synthetic and surface water. With an amount of 0.5 g of the nanocomposites, no bacteria was observed in the water after 70 min of contact time with initial bacteria concentration of 200 cfu/ml for synthetic water and within a min, no bacteria was observed in the water for surface water. It is worth noting that 200 cfu/ml is the bacteria concentration range in which environmental water is likely to contain. Therefore, the results of this study have indicated that the alginate nanocomposites can be deemed as a potential antimicrobial agent for water disinfection. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Effect of drinking water disinfection by-products in human peripheral blood lymphocytes and sperm.

    Science.gov (United States)

    Ali, Aftab; Kurzawa-Zegota, Malgorzata; Najafzadeh, Mojgan; Gopalan, Rajendran C; Plewa, Michael J; Anderson, Diana

    2014-12-01

    Drinking water disinfection by-products (DBPs) are generated by the chemical disinfection of water and may pose hazards to public health. Two major classes of DBPs are found in finished drinking water: haloacetic acids (HAAs) and trihalomethanes (THMs). HAAs are formed following disinfection with chlorine, which reacts with iodide and bromide in the water. Previously the HAAs were shown to be cytotoxic, genotoxic, mutagenic, teratogenic and carcinogenic. To determine the effect of HAAs in human somatic and germ cells and whether oxidative stress is involved in genotoxic action. In the present study both somatic and germ cells have been examined as peripheral blood lymphocytes and sperm. The effects of three HAA compounds: iodoacetic acid (IAA), bromoacetic acid (BAA) and chloroacetic acid (CAA) were investigated. After determining appropriate concentration responses, oxygen radical involvement with the antioxidants, butylated hydroxanisole (BHA) and the enzyme catalase, were investigated in the single cell gel electrophoresis (Comet) assay under alkaline conditions, >pH 13 and the micronucleus assay. In the Comet assay, BHA and catalase were able to reduce DNA damage in each cell type compared to HAA alone. In the micronucleus assay, micronuclei (MNi) were found in peripheral lymphocytes exposed to all three HAAs and catalase and BHA were in general, able to reduce MNi induction, suggesting oxygen radicals play a role in both assays. These observations are of concern to public health since both human somatic and germ cells show similar genotoxic responses. Copyright © 2014. Published by Elsevier B.V.

  7. Occurrence and control of nitrogenous disinfection by-products in drinking water--a review.

    Science.gov (United States)

    Bond, Tom; Huang, Jin; Templeton, Michael R; Graham, Nigel

    2011-10-01

    The presence of nitrogenous disinfection by-products (N-DBPs), including nitrosamines, cyanogen halides, haloacetonitriles, haloacetamides and halonitromethanes, in drinking water is of concern due to their high genotoxicity and cytotoxicity compared with regulated DBPs. Occurrence of N-DBPs is likely to increase if water sources become impacted by wastewater and algae. Moreover, a shift from chlorination to chloramination, an option for water providers wanting to reduce regulated DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs), can also increase certain N-DBPs. This paper provides a critical review of the occurrence and control of N-DBPs. Data collated from surveys undertaken in the United States and Scotland were used to calculate that the sum of analysed halonitromethanes represented 3-4% of the mass of THMs on a median basis; with Pearson product moment correlation coefficients of 0.78 and 0.83 between formation of dihaloacetonitriles and that of THMs and HAAs respectively. The impact of water treatment processes on N-DBP formation is complex and variable. While coagulation and filtration are of moderate efficacy for the removal of N-DBP precursors, such as amino acids and amines, biofiltration, if used prior to disinfection, is particularly successful at removing cyanogen halide precursors. Oxidation before final disinfection can increase halonitromethane formation and decrease N-nitrosodimethylamine, and chloramination is likely to increase cyanogen halides and NDMA relative to chlorination. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Photoelectrocatalytic disinfection of water and wastewater: performance evaluation by qPCR and culture techniques.

    Science.gov (United States)

    Venieri, Danae; Chatzisymeon, Efthalia; Politi, Eleonora; Sofianos, Spiridon S; Katsaounis, Alexandros; Mantzavinos, Dionissios

    2013-03-01

    Photoelectrocatalytic oxidation (PEC) was evaluated as a disinfection technique using water and secondary treated wastewater spiked with Escherichia coli and Enterococcus faecalis. PEC experiments were carried out using a TiO(2)/Ti-film anode and a zirconium cathode under simulated solar radiation. Bacterial inactivation was monitored by culture and quantitative polymerase chain reaction (qPCR). Inactivation rates were enhanced when the duration of the treatment was prolonged and when the bacterial density and the complexity of the water matrix were decreased. E. coli cells were reduced by approximately 6 orders of magnitude after 15 min of PEC treatment in water at 2V of applied potential and an initial concentration of 10(7) CFU/mL; pure photocatalysis (PC) led to about 5 log reduction, while electrochemical oxidation alone resulted in negligible inactivation. The superiority of PEC relative to PC can be attributed to a more efficient separation of the photogenerated charge carriers. Regarding disinfection in mixed bacterial suspensions, E. coli was more susceptible than E. faecalis at a potential of 2V. The complex composition of wastewater affected disinfection efficiency, yielding lower inactivation rates compared to water treatment. qPCR yielded lower inactivation rates at longer treatment times than culture techniques, presumably due to the fact that the latter do not take into account the viable but not culturable state of microorganisms.

  9. Solar disinfection of poliovirus and Acanthamoeba polyphaga cysts in water - a laboratory study using simulated sunlight.

    Science.gov (United States)

    Heaselgrave, W; Patel, N; Kilvington, S; Kehoe, S C; McGuigan, K G

    2006-08-01

    To determine the efficacy of solar disinfection (SODIS) in disinfecting water contaminated with poliovirus and Acanthamoeba polyphaga cysts. Organisms were subjected to a simulated global solar irradiance of 850 Wm(-2) in water temperatures between 25 and 55 degrees C. SODIS at 25 degrees C totally inactivated poliovirus after 6-h exposure (reduction of 4.4 log units). No SODIS-induced reduction in A. polyphaga cyst viability was observed for sample temperatures below 45 degrees C. Total cyst inactivation was only observed after 6-h SODIS exposure at 50 degrees C (3.6 log unit reduction) and after 4 h at 55 degrees C (3.3 log unit reduction). SODIS is an effective means of disinfecting water contaminated with poliovirus and A. polyphaga cysts, provided water temperatures of 50-55 degrees C are attained in the latter case. This research presents the first SODIS inactivation curve for poliovirus and provides further evidence that batch SODIS provides effective protection against waterborne protozoan cysts.

  10. Microbiological effectiveness of disinfecting water by boiling in rural Guatemala.

    Science.gov (United States)

    Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

    2010-03-01

    Boiling is the most common means of treating water in the home and the benchmark against which alternative point-of-use water treatment options must be compared. In a 5-week study in rural Guatemala among 45 households who claimed they always or almost always boiled their drinking water, boiling was associated with a 86.2% reduction in geometric mean thermotolerant coliforms (TTC) (N = 206, P water, 71.2% of stored water samples from self-reported boilers met the World Health Organization guidelines for safe drinking water (0 TTC/100 mL), and 10.7% fell within the commonly accepted low-risk category of (1-10 TTC/100 mL). As actually practiced in the study community, boiling significantly improved the microbiological quality of drinking water, though boiled and stored drinking water is not always free of fecal contaminations.

  11. Solar Water Disinfection in Household Settings: Hype or Hope?

    OpenAIRE

    M?usezahl, Daniel; Christen, Andri; Pacheco, Gonzalo Duran; Tellez, Fidel Alvarez; Iriarte, Mercedes; Zapata, Maria E.; Cevallos, Myriam; Hattendorf, Jan; Cattaneo, Monica Daigl; Arnold, Benjamin; Smith, Thomas A.; Colford, John M.

    2009-01-01

    Editors' Summary Background Thirsty? Well, turn on the tap and have a drink of refreshing, clean, safe water. Unfortunately, more than one billion people around the world don't have this option. Instead of the endless supply of safe drinking water that people living in affluent, developed countries take for granted, more than a third of people living in developing countries only have contaminated water from rivers, lakes, or wells to drink. Because of limited access to safe drinking water, po...

  12. Halogenated by-products of disinfecting ozonised recreational waters; Subproductos halaogenados de desinfeccion en aguas recreacionales ozonizadas

    Energy Technology Data Exchange (ETDEWEB)

    Goma i Huguet, A.; Quintana i Comte, J.; Soler i Vilaro, J.

    2005-07-01

    Recreational water like the present in swimming pools suffers, more than water from supply, formation of certain by-products in the local disinfection system because a mechanism of accumulation. Using advanced oxidation process, like onization, drives to a reduction of such an effect. Assessment of the presence of these disinfection by-products with and without onization, as well as the discussion of certain key aspects of how to ozonate, are the aim of this paper. (Author) 7 refs.

  13. Solar water disinfection by singlet oxygen photogenerated with polymer-supported Ru(II) sensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Hernandez, M. Emilia; Manjon, Francisco; Garcia-Fresnadillo, David; Orellana, Guillermo [Laboratory of Applied Photochemistry, Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2006-10-15

    Using Escherichia coli and Enterococcus faecalis as model microorganisms, water disinfection has been demonstrated with singlet molecular oxygen (a reactive oxygen species) photogenerated by polymer-supported Ru(II) sensitizers and solar light. Both laboratory and sunlight tests were performed. The Ru(II) polypyridyl complex and its insoluble support have been optimized to provide maximum efficiency of singlet oxygen production and contact with the microorganism. (author)

  14. Silver-based Antibacterial Surfaces for Drinking Water Disinfection - An overview

    Science.gov (United States)

    Risks associated with current disinfection techniques, including the formation of disinfection by-products and multi-drug resistant bacterial species, have prompted the exploration of advanced disinfection methods. One such technique employs silver nanoparticles incorporation on ...

  15. Water Purification and Disinfection by using Solar Energy: Towards Green Energy Challenge

    Directory of Open Access Journals (Sweden)

    Md Z.H. Khan

    2015-12-01

    Full Text Available The aim of this work was to design a solar water treatment plant for household purpose. Water purification is the process of eradicating detrimental chemicals, biological poisons, suspended solids and gases from contaminated water. In this work we have reported an investigation of compact filter which is cost effective for developing countries and ease of maintenance. We have arranged a solar water disinfection system that improves the microbiological quality of drinking water at household level. We get 14 L pure water and 16 ml water vapour within 240 min by using filtration method. From our work we get hot water up to 49°C. The efficiency of the system at sunny days and cloudy days are 18.23% and 18.13% respectively. This simple solar hybrid system helps to remove turbidity as well as chemical and pathogenic contaminants from water sources in the most affordable, and expedient manner possibly.

  16. Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.

    Science.gov (United States)

    Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

    2015-01-01

    Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a drinking water treatment plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests was performed at the laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests was performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 min after ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, mesoporous GAC. Therefore, this carbon removes organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and UV absorbance at wavelength 254 nm using mineral carbons; therefore, the use of a mineral mesoporous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP.

  17. Effect of ultrasonic pretreatment on purified water disinfection; Efecto del pretratamiento con ultrasonidos sobre la desinfeccion de agua depurada

    Energy Technology Data Exchange (ETDEWEB)

    Simon Andreu, P.; Lardin Mifsut, C.; Vergara Romero, L.; Polo Canas, P. M.; Perez Sanchez, P.; Rancano Perez, A.

    2009-07-01

    Due to the importance of a suitable water disinfection in order to insure a pollutant effect minimization against environment, this work has been carried out to determine how can affect an ultrasonic pre-treatment upon disinfection step. It has been confirmed the ultrasonic disintegration of bacterial cells in treated water and disinfectant power of treatment by itself, which is not enough to be used as a single method in water disinfection. It has also been proved that from a technical and economical point of view the combination of UV and ultrasound improves the UV treatment performance. Finally, it has been detected that an ultrasonic pre-treatment increases chlorination effectiveness, however the high cost in this combination makes it unfeasible of industrial scale. (Author) 6 refs.

  18. The Use of Genetic Algorithms in UV Disinfection of Drinking Water

    Directory of Open Access Journals (Sweden)

    Hugo Zaldaña

    2015-06-01

    Full Text Available In order to have drinking water, some countries have to use chlorine. It is use cause is effective and it’s cheap. An alternative to this process is the UV disinfection of drinking water. Most of the devices in the market use UV bulbs or mercury lamps. The UV LED, which is cheaper and smaller, allows creating new smaller devices. The main contribution of this paper is the use of Genetic Algorithms to help design a drinking water device with UV LEDs.

  19. Factors from the transtheoretical model differentiating between solar water disinfection (SODIS) user groups.

    Science.gov (United States)

    Kraemer, Silvie M; Mosler, Hans-Joachim

    2011-01-01

    Solar water disinfection (SODIS) is a sustainable household water treatment technique that could prevent millions of deaths caused by diarrhoea. The behaviour change process necessary to move from drinking raw water to drinking SODIS is analysed with the Transtheoretical Model of Change (TTM). User groups and psychological factors that differentiate between types of users are identified. Results of a 1.5 year longitudinal study in Zimbabwe reveal distinguishing factors between groups, from which it can be deduced that they drive the development of user groups. Implications are drawn for campaigns with the aim of bringing all user types to a regular use.

  20. Effect of disinfectant, water age, and pipe material on occurrence and persistence of Legionella, mycobacteria, Pseudomonas aeruginosa, and two amoebas.

    Science.gov (United States)

    Wang, Hong; Masters, Sheldon; Hong, Yanjuan; Stallings, Jonathan; Falkinham, Joseph O; Edwards, Marc A; Pruden, Amy

    2012-11-06

    Opportunistic pathogens represent a unique challenge because they establish and grow within drinking water systems, yet the factors stimulating their proliferation are largely unknown. The purpose of this study was to examine the influence of pipe materials, disinfectant type, and water age on occurrence and persistence of three opportunistic pathogens (Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa), broader genera (Legionella and mycobacteria), and two amoeba hosts (Acanthamoeba spp. and Hartmanella vermiformis). Triplicate simulated distribution systems (SDSs) compared iron, cement, and PVC pipe materials fed either chlorinated or chloraminated tap water and were sampled at water ages ranging from 1 day to 5.7 days. Quantitative polymerase chain reaction quantified gene copies of target microorganisms in both biofilm and bulk water. Legionella, mycobacteria, P. aeruginosa, and both amoebas naturally colonized the six SDSs, but L. pneumophila and M. avium were not detected. Disinfectant type and dose was observed to have the strongest influence on the microbiota. Disinfectant decay was noted with water age, particularly in chloraminated SDSs (due to nitrification), generally resulting in increased microbial detection frequencies and densities with water age. The influence of pipe material became apparent at water ages corresponding to low disinfectant residual. Each target microbe appeared to display a distinct response to disinfectant type, pipe materials, water age, and their interactions. Differences between the first and the second samplings (e.g., appearance of Legionella, reduction in P. aeruginosa and Acanthamoeba) suggest a temporally dynamic drinking water microbial community.

  1. Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial.

    Science.gov (United States)

    Conroy, R M; Elmore-Meegan, M; Joyce, T; McGuigan, K G; Barnes, J

    Solar radiation reduces the bacterial content of water, and may therefore offer a method for disinfection of drinking water that requires few resources and no expertise. We distributed plastic water bottles to 206 Maasai children aged 5-16 years whose drinking water was contaminated with faecal coliform bacteria. Children were instructed to fill the bottle with water and leave it in full sunlight on the roof of the hut (solar group), or to keep their filled bottles indoors in the shade (control group). A Maasai-speaking fieldworker who lived in the community interviewed the mother of each child once every 2 weeks for 12 weeks. Occurrence and severity of diarrhoea was recorded at each follow-up visit. Among the 108 children in households allocated solar treatment, diarrhoea was reported in 439 of the 2-week reporting periods during the 12-week trial (average 4.1 [SD 1.2] per child). By comparison, the 98 children in the control households reported diarrhoea during 444 2-week reporting periods (average 4.5 [1.2] per child). Diarrhoea severe enough to prevent performance of duties occurred during 186 reporting periods in the solar group and during 222 periods in the control group (average 1.7 [1.2] vs 2.3 [1.4]). After adjustment for age, solar treatment of drinking water was associated with a reduction in all diarrhoea episodes (odds ratio 0.66 [0.50-0.87]) and in episodes of severe diarrhoea (0.65 [0.50-0.86]). Our findings suggest that solar disinfection of water may significantly reduce morbidity in communities with no other means of disinfection of drinking water, because of lack of resources or in the event of a disaster.

  2. Survey of disinfection efficiency of small drinking water treatment ...

    African Journals Online (AJOL)

    A survey involving 181 water treatment plants across 7 provinces of South Africa: Mpumalanga, Limpopo, North West, Free State, KwaZulu-Natal, Eastern Cape and Western Cape was undertaken to identify the challenges facing small water treatment plants (SWTPs) in South Africa . Information gathered included ...

  3. Silver nanowire-carbon fiber cloth nanocomposites synthesized by UV curing adhesive for electrochemical point-of-use water disinfection.

    Science.gov (United States)

    Hong, Xuesen; Wen, Junjie; Xiong, Xuhua; Hu, Yongyou

    2016-07-01

    Novel silver nanowire (AgNW) - carbon fiber cloth (CC) nanocomposites were synthesized by a rapid and facile method. Acting as filter in an electrical gravity filtration device, the AgNW-CC nanocomposites were applied to electrochemical point-of-use water disinfection. AgNW-CC nanocomposites were characterized by FESEM, XRD, and FTIR. Their disinfection performance toward Escherichia coli and bacteriophage MS2 was evaluated by inhibition zone tests, optical density growth curve tests, and flow tests. The results showed that complex 3D AgNW networks with controllable silver release (<100 ppb) were fabricated on CC by using UV curing adhesive. AgNW-CC nanocomposites exhibited excellent intrinsic antibacterial activities against E. coli. The concentration of AgNWs and UV adhesive controlled the released silver and hence led to the change in antibacterial activity. The external electric field significantly enhanced the disinfection efficiency of AgNW-CC nanocomposites. Over 99.999% removal of E. coli and MS2 could be achieved. More complex AgNW networks contributed to higher disinfection efficiency under 10 V and 10(6) CFU (PFU) mL(-1) of microorganism. UV adhesive could keep the disinfection performance from being affected by flow rate. The convenient synthesis and outstanding disinfection performance offer AgNW-CC nanocomposites opportunities in the application of electrochemical point-of-use drinking water disinfection. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Microbiological effectiveness and cost of boiling to disinfect drinking water in rural Vietnam.

    Science.gov (United States)

    Clasen, Thomas F; Thao, Do Hoang; Boisson, Sophie; Shipin, Oleg

    2008-06-15

    Despite certain shortcomings, boiling is still the most common means of treating water in the home and the benchmark against which alternative household-based disinfection and filtration methods must be measured. We assessed the microbiological effectiveness and cost of boiling among a vulnerable population relying on unimproved water sources and commonly practicing boiling as a means of disinfecting water. In a 12 week study among 50 households from a rural community in Vietnam, boiling was associated with a 97% reduction in geometric mean thermotolerant coliforms (TTCs) (p water, 37% of stored water samples from self-reported boilers met the WHO standard for safe drinking water (0 TTC/100 mL), and 38.3% fell within the low risk category (1--10 TTC/100 mL). Nevertheless, 60.5% of stored drinking water samples were positive for TTC, with 22.2% falling into the medium risk category (11--100 TTC/100 mL). The estimated cost of wood used to boil water was US$ 0.272 per month for wood collectors and US$ 1.68 per month for wood purchasers, representing approximately 0.48% to 1.04%, respectively, of the average monthly income of participating households.

  5. Evaluation of the Solar Water Disinfection Method Using an Ultraviolet Measurement Device

    Science.gov (United States)

    Leung, H.

    2015-12-01

    Drinking water security is a growing problem for the population of planet Earth. According to WHO, more than 750 million people on our planet lack access to safe drinking water, resulting in approximately 502,000 diarrhoea deaths in 2012. In order to solve this problem, the Swiss water research institute, Eawag, has developed a method of solar water disinfection, called, "SODIS" The theory of SODIS is simple to understand: a clear plastic bottle filled with water is placed under full sunlight for at least 6 hours. The ultraviolet radiation kills the pathogens in the water, making the originally contaminated water safe for drinking. In order to improve this method, Helioz, an Austrian social enterprise, has created the WADI, a UV measurement device which determines when water is safe for drinking using the SODIS method. When using the WADI, the device should be placed under the sun and surrounded with bottles of water that need to be decontaminated. There is a UV sensor on the WADI, and since the bottles of water and the WADI will have equal exposure to sunlight, the WADI will be able to measure the impact of the sunlight on the contaminated water. This experiment tests the accuracy of the WADI device regarding the time interval needed for contaminated water to be disinfected. The experiment involves using the SODIS method to purify bottles of water contaminated with controlled samples of E. coli. Samples of the water are taken at different time intervals, and the E. coli levels are determined by growing the bacteria from the water samples on agar plates. Ultimately, this helps determine when the water is safe for drinking, and are compared against the WADI's measurements to test the reliability of the device.

  6. Bioanalytical and chemical evaluation of disinfection by-products in swimming pool water.

    Science.gov (United States)

    Yeh, Ruby Y L; Farré, Maria José; Stalter, Daniel; Tang, Janet Y M; Molendijk, Jeffrey; Escher, Beate I

    2014-08-01

    Pool water disinfection is vital to prevent microbial pathogens. However, potentially hazardous disinfection by-products (DBP) are formed from the reaction between disinfectants and organic/inorganic precursors. The aim of this study was to evaluate the presence of DBPs in various swimming pool types in Brisbane, Australia, including outdoor, indoor and baby pools, and the dynamics after a complete water renewal. Chemical analysis of 36 regulated and commonly found DBPs and total adsorbable organic halogens as well as in vitro bioassays targeting cytotoxicity, oxidative stress and genotoxicity were used to evaluate swimming pool water quality. Dichloroacetic acid and trichloroacetic acid dominated in the pool water samples with higher levels (up to 2600 μg/L) than the health guideline values set by the Australian Drinking Water Guidelines (100 μg/L). Chlorinated DBPs occurred at higher concentrations compared to tap water, while brominated DBPs decreased gradually with increasing pool water age. Biological effects were expressed as chloroacetic acid equivalent concentrations and compared to predicted effects from chemical analysis and biological characterisation of haloacetic acids. The quantified haloacetic acids explained 35-118% of the absorbable organic halogens but less than 4% of the observed non-specific toxicity (cytotoxicity), and less than 1% of the observed oxidative stress response and genotoxicity. While the DBP concentrations in Australian pools found in this study are not likely to cause any adverse health effect, they are higher than in other countries and could be reduced by better hygiene of pool users, such as thorough showering prior to entering the pool and avoiding urination during swimming. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Assessing the genotoxicity of two commonly occurring byproducts of water disinfection: Chloral hydrate and bromal hydrate.

    Science.gov (United States)

    Manasfi, Tarek; De Méo, Michel; Di Giorgio, Carole; Coulomb, Bruno; Boudenne, Jean-Luc

    2017-01-01

    Water disinfection treatments result in the formation of disinfection byproducts (DBPs) that have been linked to adverse human health outcomes including higher incidence of bladder and colorectal cancer. However, data about the genotoxicity of DBPs is limited to only a small fraction of compounds. Chloral hydrate (CH) and bromal hydrate (BH) are two trihaloacetaldehydes commonly detected in disinfected waters, but little is known about their genotoxicity, especially BH. We investigated the genotoxicity of CH and BH using a test battery that includes three in vitro genotoxicity assays. We conducted the Ames test using Salmonella bacterial strains TA97a, TA98, TA100 and TA102, and the alkaline comet assay and the micronucleus test both using Chinese hamster ovary cells. We carried out the tests in the absence and presence of the metabolic fraction S9 mix. CH did not exhibit statistically significant genotoxic effects in any of the three assays. In contrast, BH exhibited mutagenic activity in the Salmonella strain TA100 and induced statistically significant DNA lesions in CHO cells as appeared in the comet assay. The genotoxic potential of BH in both assays decreased in the presence of the metabolic fraction S9 mix. BH did not induce chromosomal damage in CHO cells. Our results show that BH exhibited genotoxic activity by causing mutations and primary DNA damage while CH did not induce genotoxic effects. Our findings highlight concerns about the higher genotoxicity of brominated DBPs in comparison to their chlorinated analogues. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Evaluation of Disinfectants Used in Pre-Chilling water Tanks of Poultry Processing Plants

    Directory of Open Access Journals (Sweden)

    BHL Guastalli

    Full Text Available ABSTRACT In poultry processing plants, disinfectants are often added to pre-chilling water tanks to reduce microbial contamination. The present study aimed at evaluating the effect of five disinfectants (acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride, chlorine dioxide, peracetic acid, and sodium hypochlorite on the populations of food quality indicator microorganisms and on Salmonella Enteritidis (SE in the presence and absence of organic matter. The results showed that chlorine dioxide and sodium hypochlorite did not reduce microbial carcass counts. On the other hand, acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid reduced total and fecal coliform counts. Peracetic acid reduced the number of psychrotrophic microorganisms. All products were effective in reducing SE counts only in the absence of organic matter. Acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid could be candidates for the replacement of sodium hypochlorite (commonly used in Brazil in pre-chilling tanks.

  9. Use of solar energy for disinfection of polluted water

    Directory of Open Access Journals (Sweden)

    Y. Jamil

    2009-05-01

    Full Text Available Polluted water is causing serious health problems especially in the rural areas of Pakistan. People have limited access to safe water supply and many diseases like diarrhea and gastrointestinal diseases are transmitted by consumption of polluted water. We have investigated the potential of using solar energy to pasteurize water. Low cost indigenously available materials have been utilized to design and fabricate a solar box type pasteurizer having a capacity of three liters. The performance study of the pasteurizer was performed during the month of May 2008. The designed pasteurizer maintained water temperature in the range of60 oC to 70 oC continuously for more than an hour which is enough for deactivation of coliform bacteria. The maximum water temperature on a clear sunny day was found to be 67 oC, corresponding to an ambient temperature of40 oC. With the pasteurizer facing south, a very little repositioning was required. The low cost and operational simplicity of the pasteurizer make it affordable and usable. It is more useful in rural areas where other sources of energy like electricity and gas are not easily available

  10. [Study on pipe material's influence on chlorine dioxide drinking water disinfection].

    Science.gov (United States)

    He, Tao; Yue, Yinling; Ling, Bo; Zhang, Lan

    2010-09-01

    To study the pipe material's influence on chlorine dioxide drinking water disinfection. 0.8 mg/L chlorine dioxide solution was injected into 5 kinds of pipes respectively, PPR, PVC-U, Steel with Zinc coating, copper and PE pipes. Dipped free from light for 48 hours and the concentrations of chlorine dioxide, chlorite and chlorate were tested from samples taken from each kind of pipe at 1, 2, 3, 4, 5, 6, 12, 24 and 48 hours respectively. Chlorine dioxides decay rates in the water dipping the pipes increase as the dipping time increases and the decay of chlorine dioxide mainly occurs within 6 hours after the dipping. But for different pipe, the influence of decay differs. The consumption of chlorine dioxide of the metal pipes is more than that of the plastic pipes. And with 2 hours after the dipping experiment begins, the concentrations of the chlorite of the copper pipe and of the steel with zinc coating pipe increase quickly and reach the maximum concentration. But then the chlorite concentration decreases greatly. After dipped 24 hours, the chlorite in the water in the pipe can not be detected. For other plastic piples, all the chlorite concentrations in the dipping water increase as the dipping time increase. Compared with the start of the dipping experiment, the chlorate concentration in the dipping water of each pipe has no obvious change. The material of the water transportation pipe does have influence on chlorine dioxide drinking water disinfection.

  11. Frequency of use controls chemical leaching from drinking-water containers subject to disinfection.

    Science.gov (United States)

    Andra, Syam S; Makris, Konstantinos C; Shine, James P

    2011-12-15

    Microbial-, and chemical-based burden of disease associated with lack of access to safe water continues to primarily impact developing countries. Cost-effective health risk-mitigating measures, such as of solar disinfection applied to microbial-contaminated water stored in plastic bottles have been increasingly tested in developing countries adversely impacted by epidemic water-borne diseases. Public health concerns associated with chemical leaching from water packaging materials led us to investigate the magnitude and variability of antimony (Sb) and bromine (Br) leaching from reused plastic containers (polyethylene terephthalate, PET; and polycarbonate, PC) subject to UV and/or temperature-driven disinfection. The overall objective of this study was to determine the main and interactive effects of temperature, UV exposure duration, and frequency of bottle reuse on the extent of leaching of Sb and Br from plastic bottles into water. Regardless of UV exposure duration, frequency of reuse (up to 27 times) was the major factor that linearly increased Sb leaching from PET bottles at all temperatures tested (13-47 °C). Leached Sb concentrations (∼360 ng L(-1)) from the highly reused (27 times) PET bottles (minimal Sb leaching from PC bottles, water at much lower concentrations. Additional research on potential leaching of organic chemicals from water packaging materials is deemed necessary under relevant environmental conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Socioeconomic status and exposure to disinfection by-products in drinking water in Spain

    Directory of Open Access Journals (Sweden)

    Serra Consol

    2011-03-01

    Full Text Available Abstract Background Disinfection by-products in drinking water are chemical contaminants that have been associated with cancer and other adverse effects. Exposure occurs from consumption of tap water, inhalation and dermal absorption. Methods We determined the relationship between socioeconomic status and exposure to disinfection by-products in 1271 controls from a multicentric bladder cancer case-control study in Spain. Information on lifetime drinking water sources, swimming pool attendance, showering-bathing practices, and socioeconomic status (education, income was collected through personal interviews. Results The most highly educated subjects consumed less tap water (57% and more bottled water (33% than illiterate subjects (69% and 17% respectively, p-value = 0.003. These differences became wider in recent time periods. The time spent bathing or showering was positively correlated with attained educational level (p Conclusions The most highly educated subjects were less exposed to chlorination by-products through ingestion but more exposed through dermal contact and inhalation in pools and showers/baths. Health risk perceptions and economic capacity may affect patterns of water consumption that can result in differences in exposure to water contaminants.

  13. Disinfection of Pythium-infested recirculation water by UV-oxidation technology.

    Science.gov (United States)

    Runia, W T; Boonstra, S

    2001-01-01

    Selective disinfection against Pythium aphanidermatum in recirculation water was tested with UV-irradiation and with UV-oxidation technology with the objective to reduce the electrical energy consumption per cubic meter treated water. UV-oxidation technology is based on injection of hydrogen peroxide in recirculation water, just before passage along a UV-lamp, thus creating hydroxyl radicals. Pythium aphanidermatum was applied artificially to recirculation water from tomatoes, grown, in rockwool and coconut fibre. Other parameters in this study were pH and transmission value (T10) of the infested recirculation water. Results indicated that the recommended UV-C dose of 100 mJ/cm2 for elimination of fungal pathogens in general can be lowered in case recirculation water is infected with Pythium aphanidermatum only. When UV-oxidation technology was applied with 1 mmol hydrogen peroxide per litre recirculation water, the UV-C dose could be reduced even more in comparison with merely UV irradiation.

  14. Potential application of high pressure carbon dioxide in treated wastewater and water disinfection: Recent overview and further trends.

    Science.gov (United States)

    Vo, Huy Thanh; Imai, Tsuyoshi; Ho, Truc Thanh; Dang, Thanh-Loc Thi; Hoang, Son Anh

    2015-10-01

    Recently emerging disadvantages in conventional disinfection have heightened the need for finding a new solution. Developments in the use of high pressure carbon dioxide for food preservation and sterilization have led to a renewed interest in its applicability in wastewater treatment and water disinfection. Pressurized CO2 is one of the most investigated methods of antibacterial treatment and has been used extensively for decades to inhibit pathogens in dried food and liquid products. This study reviews the literature concerning the utility of CO2 as a disinfecting agent, and the pathogen inactivation mechanism of CO2 treatment is evaluated based on all available research. In this paper, it will be argued that the successful application and high effectiveness of CO2 treatment in liquid foods open a potential opportunity for its use in wastewater treatment and water disinfection. The findings from models with different operating conditions (pressure, temperature, microorganism, water content, media …) suggest that most microorganisms are successfully inhibited under CO2 treatment. It will also be shown that the bacterial deaths under CO2 treatment can be explained by many different mechanisms. Moreover, the findings in this study can help to address the recently emerging problems in water disinfection, such as disinfection by-products (resulting from chlorination or ozone treatment). Copyright © 2015. Published by Elsevier B.V.

  15. Microbial disinfection of water with endotoxin degradation by photocatalysis using Ag@TiO2 core shell nanoparticles.

    Science.gov (United States)

    S, Sreeja; K, Vidya Shetty

    2016-09-01

    The studies on photocatalytic disinfection of water contaminated with Escherichia coli using Ag core and TiO2 shell (Ag@TiO2) nanoparticles under UV irradiation showed that these nanoparticles are very efficient in water disinfection both in their free and immobilised form. Complete disinfection of 40 × 10(8) CFU/mL could be achieved in 60 min with 0.4 g/L catalyst loading and in 35 min with 1 g/L catalyst loading. Ag@TiO2 nanoparticles were found to be superior to TiO2 nanoparticles in photocatalytic disinfection of water. Kinetics of disinfection followed Chick's law, and the pseudo-first-order rate constant was 0.0168 min(-1) for a catalyst loading of 0.1 g/L. Disinfection of water and degradation of endotoxins (harmful disinfection residual) occurred simultaneously during photocatalysis thereby making the treated water safe for use. Endotoxin degradation showed a shifting order of kinetics. The rate of photocatalysis with nanoparticles immobilised in cellulose acetate film was marginally lower as compared to that of free nanoparticles. Negligible Ag ion leakage and re-growth of cells post-photo-catalytic treatment of water confirmed that complete disintegration of E. coli occurred during photocatalysis making the treated water safe for use. Therefore, Ag@TiO2 nanoparticles have a potential for large-scale application in drinking water treatment plants and household purification units.

  16. [Water disinfection by the combined exposure to super-high frequency energy and available chlorine produced during water electrolysis].

    Science.gov (United States)

    Klimarev, S I; Siniak, Iu E

    2014-01-01

    The article reports the results of studying the effects on polluted water of SHF-energy together with the residual free (active) chlorine as a by-product of electrolysis action on dissolved chlorine-containing salts. Purpose of the studies was to evaluate input of these elements to the water disinfection effect. The synergy was found to kill microorganisms without impacts on the physicochemical properties of processed water or nutrient medium; therefore, it can be used for water treatment, and cultivation of microorganisms in microbiology.

  17. Solar disinfection of wastewater to reduce contamination of lettuce crops by Escherichia coli in reclaimed water irrigation.

    Science.gov (United States)

    Bichai, Françoise; Polo-López, M Inmaculada; Fernández Ibañez, Pilar

    2012-11-15

    Low-cost disinfection methods to allow safe use of recycled wastewater for irrigation can have important beneficial implications in the developing world. This study aims to assess the efficiency of solar disinfection to reduce microbial contamination of lettuce crops when solar-treated wastewater effluents are used for irrigation. The irrigation study was designed as a complete experimental loop, including (i) the production of irrigation water through solar disinfection of real municipal wastewater treatment plant effluents (WWTPE), (ii) the watering of cultivated lettuce crops at the end of solar treatment, and (iii) the detection of microbial contamination on the irrigated crops 24 h after irrigation. Solar disinfection was performed using two types of reactors: (i) 20-L batch borosilicate glass reactors equipped with CPC to optimize solar irradiation, and (ii) 1.5-L PET bottles, i.e. the traditional SODIS recipients commonly used for disinfection of drinking water in developing communities. Both solar and H(2)O(2)-aided solar disinfection processes were tested during ≤5 h exposure of WWTPE, and Escherichia coli inactivation was analysed. A presence/absence detection method was developed to analyse lettuce leaves sampled 24 h after watering for the detection of E. coli. Results of inactivation assays show that solar disinfection processes can bring down bacterial concentrations of >10(3)-10(4)E. coli CFU mL(-1) in real WWTPE to <2 CFU/mL (detection limit). The absence of E. coli on most lettuce samples after irrigation with solar-disinfected effluents (26 negative samples/28) confirmed an improved safety of irrigation practices due to solar treatment, while crops irrigated with raw WWTPE showed contamination. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Metagenomic Analyses of Drinking Water Receiving Different Disinfection Treatments

    Science.gov (United States)

    A metagenome-based approach was utilized for assessing the taxonomic affiliation and function potential of microbial populations in free chlorine (CHL) and monochloramine (CHM) treated drinking water (DW). A total of 1,024, 242 (averaging 544 bp) and 849, 349 (averaging 554 bp) ...

  19. Chlorine Disinfection in the Use of Individual Water Purification Devices

    Science.gov (United States)

    2006-03-01

    Salmonella typhi, and Shigella dysenteriae showed that HOCl is more effective than OCl- for inactivation of these bacteria (reference 21). Further...Protection Agency (EPA), Registration Division Office of Pesticide Program, Criteria and Standards Division Office of Drinking Water, 1987. Guide

  20. Organic chloramines in chlorine-based disinfected water systems: A critical review.

    Science.gov (United States)

    How, Zuo Tong; Kristiana, Ina; Busetti, Francesco; Linge, Kathryn L; Joll, Cynthia A

    2017-08-01

    This paper is a critical review of current knowledge of organic chloramines in water systems, including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine (the difference between the measured free and total chlorine concentrations), and may include N-chloramines, N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic monochloramines. However, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation. Copyright © 2017. Published by Elsevier B.V.

  1. Tracking disinfection by-products and arsenic removal during various drinking water treatment trains.

    Science.gov (United States)

    Tubić, Aleksandra; Dalmacija, Bozo; Agbaba, Jasmina; Ivancev-Tumbas, Ivana; Klasnja, Mile; Dalmacija, Milena

    2010-01-01

    In the central Banat region (Northern Serbia), groundwater is used as a drinking water source. Raw water originates from a 40-80 m and 100-150 m deep layer. It contains a high amount of natural organic matter (DOC = 9.17+/-0.87 mg C/L) with a trihalomethanes formation potential of 448+/-88.2 microg/L and a haloacetic acid formation potential of 174+/-68.9 microg/L. A high amount of arsenic (86.0+/-3.4 microg/L) is also found in this water. This study used a pilot-scale system to investigate the possibilities of combining polyaluminium chloride and ferrous-chloride to remove disinfection by-products precursors and arsenic by coagulation. Two treatment trains with different pre-treatment steps were investigated (ozone vs. H2O2/O3). For the final water polishing, filtration with granulated activated carbon (GAC) was applied. Both investigated treatment lines achieved a satisfactory chemical water quality. Simulation of disinfection conditions was performed and the contents of trihalomethanes and haloacetic acids measured, to investigate whether the chemical quality of the water remained satisfactory over a 48 hour period.

  2. Disinfection and reduction of organic load of sewage water by electron beam radiation

    Science.gov (United States)

    Maruthi, Y. Avasn; Das, N. Lakshmana; Hossain, Kaizar; Sarma, K. S. S.; Rawat, K. P.; Sabharwal, S.

    2011-09-01

    The efficacy of electron beam radiation for the disinfection and reduction of organic load of sewage water was assessed with ILU-6 Accelerator at Radiation Technology Development Division of the Bhabha Atomic Research Centre, Mumbai India. The current problem on environmental health in relation to water pollution insists for the safe disposal of sewage water. In general, sewage water comprises heterogeneous organic based chemicals as well as pathogens. EB treatment of the wastewater has found to be very effective in reducing the pathogens as well as organic load. EB dose of 1.5 kGy was sufficient for complete elimination of total coli forms. The experimental results elucidated the reduction of biological oxygen demand—BOD (35 and 51.7%) in both inlet and outlet sewage samples. Similarly reduction of chemical oxygen demand—COD was observed (37.54 and 52.32%) in both sewage samples with respect to increase in irradiation doses (0.45-6 kGy). The present study demonstrated the potential of ionizing radiation for disinfection of sewage and to increase the water quality of the wastewater by decreasing BOD and COD. So, the irradiation sewage water can find its application either in agriculture for irrigation, in industry for cooling purpose and some selected domestic purposes.

  3. Comparison of media for enumeration of coliform bacteria and Escherichia coli in non-disinfected water.

    Science.gov (United States)

    Pitkänen, Tarja; Paakkari, Piia; Miettinen, Ilkka T; Heinonen-Tanski, Helvi; Paulin, Lars; Hänninen, Marja-Liisa

    2007-03-01

    In this work alternative media for detection and enumeration of E. coli and coliform bacteria were compared to the reference method ISO 9308-1 (LTTC) using non-disinfected water samples with background flora. The alternative media included LES Endo agar medium (LES Endo), Colilert-18 with 51-well Quanti-tray (Colilert), Chromocult Coliform agar (CC), Harlequin E. coli/Coliform medium (HECM) and Chromogenic Escherichia coli/Coliform medium (CECM). A total of 110 samples of groundwater, bathing water and spiked water was used. Our results revealed that confirmation of coliform bacteria counts is necessary, not only on lactose-based LTTC and LES Endo media, but also on the chromogenic agar media tested, due to the growth of oxidase positive colonies. LTTC and CC media also allowed the growth of some morphologically typical coliform colonies containing gram-positive bacteria. The recovery of coliform bacteria was lower on LES Endo than on LTTC. In most cases Colilert, CC, HECM and CECM gave higher coliform counts than LTTC. The use of the LTTC medium led to higher E. coli counts than obtained with any of the alternative mediums. There are three explanations for this: (1) high sensitivity of LTTC, (2) false positives on LTTC or (3) false negatives especially with Colilert, but also with chromogenic agar media. Although LTTC was found to be a very sensitive medium, the high degree of background growth of non-disinfected waters disturbed substantially the use of it. In conclusion, our results suggest that Colilert, CC and CECM are potential alternative media for detection of coliform bacteria and E. coli from non-disinfected water.

  4. Simple Continuous-Flow Device for Combined Solar Thermal Pasteurization and Solar Disinfection for Water Sterilization

    Directory of Open Access Journals (Sweden)

    Anthony Amsberry

    2015-02-01

    Full Text Available A collection unit and reflective concentrators were used to thermally preheat water to at least 70 °C for thermal pasteurization prior to a solar disinfection stage. The device is offered as a novel combined cycle to be used for either solar thermal pasteurization, during seasonalpeaks in solar irradiation, or as a solar preheat for UV solar disinfection which would occur in a flow-through solar disinfection trough. Inexpensive materials were used in order to simulate in field functionality and applicability to rural regions with low solar input. Solar incidence at Oregon State University, with latitude 45.5°, was recorded during trials conducted during May 1 to June 10 for the purpose of directly scaling the water treatment volumetric flowrate of the device for any future tests in other locations. This scaling by solar irradiation makes this dataset useful for other locations with higher or lower solar input and needing more or less treated water. The simple gravity-fed continuous system presented in this article makes use of a large cold water reservoir, a shell-and-tube heat exchanger, and a solar collector. The system, operating at flowrates of 100-150 mL/min is able to reach outlet temperatures of 74°C.  The system is projected to produce 55 L of purified water daily when operating on a sunny day with peak UV radiation above 700 W/m2. System cost was $55 with an added optional $15 for the shell-and-tube heat exchanger.

  5. Cyto- and genotoxic profile of groundwater used as drinking water supply before and after disinfection.

    Science.gov (United States)

    Pellacani, C; Cassoni, F; Bocchi, C; Martino, A; Pinto, G; Fontana, F; Furlini, M; Buschini, A

    2016-12-01

    The assessment of the toxicological properties of raw groundwater may be useful to predict the type and quality of tap water. Contaminants in groundwater are known to be able to affect the disinfection process, resulting in the formation of substances that are cytotoxic and/or genotoxic. Though the European directive (98/83/EC, which establishes maximum levels for contaminants in raw water (RW)) provides threshold levels for acute exposure to toxic compounds, the law does not take into account chronic exposure at low doses of pollutants present in complex mixture. The purpose of this study was to evaluate the cyto- and genotoxic load in the groundwater of two water treatment plants in Northern Italy. Water samples induced cytotoxic effects, mainly observed when human cells were treated with RW. Moreover, results indicated that the disinfection process reduced cell toxicity, independent of the biocidal used. The induction of genotoxic effects was found, in particular, when the micronucleus assay was carried out on raw groundwater. These results suggest that it is important to include bio-toxicological assays as additional parameters in water quality monitoring programs, as their use would allow the evaluation of the potential risk of groundwater for humans.

  6. Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review.

    Science.gov (United States)

    Du, Ye; Lv, Xiao-Tong; Wu, Qian-Yuan; Zhang, Da-Yin; Zhou, Yu-Ting; Peng, Lu; Hu, Hong-Ying

    2017-08-01

    Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds. Copyright © 2017. Published by Elsevier B.V.

  7. Pilot Study for UVA-LED Disinfection of Escherichia coli in Water for Space and Earth Applications

    Science.gov (United States)

    Ragolta, Carolina

    2010-01-01

    To test the efficacy of UVA-LED disinfection, a solution of Escherichia coli was pumped through a modified drip flow reactor at a flow rate of 1 ml/min. The experiment was conducted in a controlled environment chamber to ensure that temperature did not cause disinfection. The reactor featured three wells with different treatments: UVA-LED irradiation, UVA-LEDs with Ti02, and UVA-LEDs with nanosilver. Samples from each well were taken throughout a 340 hour period, inactivated, assayed, and analyzed for E. coli disinfection. Results of the duplicate experiments indicated longer exposure times are needed for UVA-LED disinfection of E. coli in water. Further research would consider a longer sampling period and different test conditions, such as increased contact area and various flow rates.

  8. FEASIBILITY STUDY OF USING COMPLEX OF HYDROGEN PEROXIDE AND SILVER FOR DISINFECTING SWIMMING POOL WATER AND ITS ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    R. Nabizadeh ، N. Samadi ، Z. Sadeghpour ، M. Beikzadeh

    2008-10-01

    Full Text Available In this research the application of Nanosil containing hydrogen peroxide and silver was studied in disinfecting swimming pool water and it's Environment. The effect of the disinfectant on Candida albicans (ATCC No. 10231, Aspergillus niger (ATCCNo. 16404, Pseudomonas aeruginosa (ATCC No. 9027, Serratia marcescens (PTCC No. 1111, Klebsiella pneumoniae (ATCC No. 10031 and Staphylococcus aureus (ATCC No. 29737 was evaluated. The main objective of this experiment was to determine the effective dose of Nanosil which could be used for disinfecting the environment of swimming pools and other surface area. Then, the effectiveness of Nanosil was studied in two private and one public swimming pools. Heterotrophic plate count, thermotolerant coliforms, Pseudomonas aeruginosa and Staphylococcus aureus were monitored as the target microorganisms in disinfection practice According to the result of this study, it is recommended to apply the Nanosil with the concentration of ≥3% (30000 mg/L for contact time of 30 min or more for practical disinfection in swimming pools environment. The application of Nanosil in real conditions of two private and one public swimming pools indicated that the acceptable microbial quality is also achievable if the disinfectant residual concentration would be as high as 20 mg/L in swimming pool water.

  9. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

    Science.gov (United States)

    Maw, Myint Myint; Wang, Junsheng; Li, Fabo; Jiang, Jinhu; Song, Younan; Pan, Xinxiang

    2015-01-01

    Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods. PMID:26516836

  10. Case study approach to modeling historical disinfection by-product exposure in Iowa drinking waters.

    Science.gov (United States)

    Krasner, Stuart W; Cantor, Kenneth P; Weyer, Peter J; Hildesheim, Mariana; Amy, Gary

    2017-08-01

    In the 1980s, a case-control epidemiologic study was conducted in Iowa (USA) to analyze the association between exposure to disinfection by-products (DBPs) and bladder cancer risk. Trihalomethanes (THMs), the most commonly measured and dominant class of DBPs in drinking water, served as a primary metric and surrogate for the full DBP mixture. Average THM exposure was calculated, based on rough estimates of past levels in Iowa. To reduce misclassification, a follow-up study was undertaken to improve estimates of past THM levels and to re-evaluate their association with cancer risk. In addition, the risk associated with haloacetic acids, another class of DBPs, was examined. In the original analysis, surface water treatment plants were assigned one of two possible THM levels depending on the point of chlorination. The re-assessment considered each utility treating surface or groundwater on a case-by-case basis. Multiple treatment/disinfection scenarios and water quality parameters were considered with actual DBP measurements to develop estimates of past levels. The highest annual average THM level in the re-analysis was 156μg/L compared to 74μg/L for the original analysis. This allowed the analysis of subjects exposed at higher levels (>96μg/L). The re-analysis established a new approach, based on case studies and an understanding of the water quality and operational parameters that impact DBP formation, for determining historical exposure. Copyright © 2017. Published by Elsevier B.V.

  11. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

    Directory of Open Access Journals (Sweden)

    Myint Myint Maw

    2015-10-01

    Full Text Available Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina algae in ballast water treated by sodium hypochlorite (NaClO solution. Light-induced chlorophyll fluorescence (LICF intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods.

  12. Wetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors.

    Science.gov (United States)

    Hansen, Angela M; Kraus, Tamara E C; Bachand, Sandra M; Horwath, William R; Bachand, Philip A M

    2017-12-06

    Constructed wetlands are used worldwide to improve water quality while also providing critical wetland habitat. However, wetlands have the potential to negatively impact drinking water quality by exporting dissolved organic carbon (DOC) that upon disinfection can form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs). We used a replicated field-scale study located on organic rich soils in California's Sacramento-San Joaquin Delta to test whether constructed flow-through wetlands which receive water high in DOC that is treated with either iron- or aluminum-based coagulants can improve water quality with respect to DBP formation. Coagulation alone removed DOC (66-77%) and THM (67-70%) precursors, and was even more effective at removing HAA precursors (77-90%). Passage of water through the wetlands increased DOC concentrations (1.5-7.5mgL-1), particularly during the warmer summer months, thereby reversing some of the benefits from coagulant addition. Despite this addition, water exiting the wetlands treated with coagulants had lower DOC and DBP precursor concentrations relative to untreated source water. Benefits of the coagulation-wetland systems were greatest during the winter months (approx. 50-70% reduction in DOC and DBP precursor concentrations) when inflow water DOC concentrations were higher and wetland DOC production was lower. Optical properties suggest DOC in this system is predominantly comprised of high molecular weight, aromatic compounds, likely derived from degraded peat soils. Published by Elsevier B.V.

  13. Effect of batch-process solar disinfection on survival of Cryptosporidium parvum oocysts in drinking water.

    Science.gov (United States)

    Méndez-Hermida, F; Castro-Hermida, J A; Ares-Mazás, E; Kehoe, S C; McGuigan, K G

    2005-03-01

    The results of batch-process solar disinfection (SODIS) of Cryptosporidium parvum oocysts in water are reported. Oocyst suspensions were exposed to simulated sunlight (830 W m(-2)) at 40 degrees C. Viability assays (4',6'-diamidino-2-phenylindole [DAPI]/propidium iodide and excystation) and infectivity tests (Swiss CD-1 suckling mice) were performed. SODIS exposures of 6 and 12 h reduced oocyst infectivity from 100% to 7.5% (standard deviation = 2.3) and 0% (standard deviation = 0.0), respectively.

  14. Safety of treated water for re-use purposes--comparison of filtration and disinfection processes.

    Science.gov (United States)

    Wang, X C; Qiu, F G; Jin, P K

    2006-01-01

    A study was conducted on the distribution of pollutants in treated wastewater and the its safety for re-use purposes. Based on the results of a series of tertiary treatment experiments, the effects of three filtration processes, i.e. coagulation-filtration, ozonation-biological activated carbon filtration (O3-BAC) and ultrafiltration (UF), and two chemical disinfection processes, i.e. chlorination and ozonation, on the safety of water re-use were evaluated. It was found that the concentrations of the main pollutants in the secondary effluent and further filtered water follow a log-normal distribution and, therefore, a log-normal probabilistic function can be used to evaluate the suitability of the treated water for re-use purposes. Among the three filtration processes evaluated, UF is the most effective in turbidity removal but less effective in colour and COD removal, while coagulation-filtration and O3-BAC can ensure a good removal of all these pollutants. Regarding chemical disinfection, although chlorine is very effective in inactivation of coliform bacteria, it can not achieve a substantial decrease in viruses. As ozone is applied, effective virus removal can be achieved.

  15. Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review.

    Science.gov (United States)

    Song, Kai; Mohseni, Madjid; Taghipour, Fariborz

    2016-05-01

    Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. [Effect of ammonia-oxidizing bacteria (AOB) on chloraminated disinfection attenuation in drinking water distribution system].

    Science.gov (United States)

    Bai, Xiao-Hui; Cai, Yun-Long; Zhou, Bin-Hui; Zhi, Xing-Hua

    2009-06-15

    The growth of microbe and formation of biofilm in water distribution system were important factors affecting the security of water quality. The number of ammonia-oxidizing bacteria (AOB) in biofilm of a chloraminated drinking water distribution system in Shanghai was detected by MPN-Griess method, and the relations among AOB, nitrification and chloraminated disinfection were analyzed. Meanwhile, the effects of AOB on chloraminated disinfection fastness and attenuation by simulation experiment were studied. The result indicated that the number of ammonia-oxidizing bacteria in pipe biofilm was between 1.0 x 10(2)-4.3 x 10(5) MPN/g dry biofilm. Correlation coefficients of AOB with ammonia, nitrite and nitrate were -0.563, 0.603 and -0.563. Correlation coefficients of AOB with total chlorine and mono-chloramine were -0.659 and -0.571. Fastness of AOB to chloramine was higher than heterotrophic bacteria and AOB can deplete more chloramine than HPC.

  17. Innovative Plasma Disinfection Technique with the Reduced-pH Method and the Plasma-Treated Water (PTW) -Safety and Powerful Disinfection with Cryopreserved PTW-

    Science.gov (United States)

    Kitano, Katsuhisa; Ikawa, Satoshi; Nakashima, Yoichi; Tani, Atsushi; Yokoyama, Takashi; Ohshima, Tomoko

    2015-09-01

    Among the applications of the plasma disinfection to human body, plasma sterilization in liquid is crucial. We found that the plasma-treated water (PTW) has strong bactericidal activity under low pH condition and the half-lives of its activity depend on temperature. Lower temperature brings longer half-life and the bactericidal activity of PTW can be kept by cryopreservation. These physicochemical properties were in accordance with Arrhenius equation both in liquid and solid states. From the experimental results of ESR (Electron Spin Resonance) measurement of O2-in liquid against PTW with spin trapping method, half-lives of PTW were also in accordance with Arrhenius equation. It suggests that high concentration PTW as integrated value can be achieved by cooling of plasma apparatus. Pure PTW has disinfection power of 22 log reduction (B. subtilis). This corresponds to 65% H2O2, 14% hypochlorous acid and 0.33% peracetic acid, which are deadly poison for human. On the other hand, PTW is deactivated soon at body temperature. This indicates that toxicity to human body seems to be low. PTW, which is a sort of indirect plasma exposure, with pH and temperature controls could be applied for safety and powerful disinfection. MEXT (15H03583, 23340176, 25108505). NCCE (23-A-15).

  18. Chlorine dioxide oxidation of Escherichia coli in water - A study of the disinfection kinetics and mechanism.

    Science.gov (United States)

    Ofori, Isaac; Maddila, Suresh; Lin, Johnson; Jonnalagadda, Sreekantha B

    2017-06-07

    This study investigated the kinetics and mechanism of chlorine dioxide (ClO2) inactivation of a Gram-negative bacteria Escherichia coli (ATCC 35218) in oxidant demand free (ODF) water in detail as a function of disinfectant concentration (0.5-5.0 mg/L), water pH (6.5-8.5), temperature variations (4-37°C) and bacterial density (105-107 cfu/mL). The effects of ClO2 on bacterial cell morphology, outer membrane permeability, cytoplasmic membrane disruption and intracellular enzymatic activity were also studied to elucidate the mechanism of action on the cells. Increasing temperature and disinfectant concentration were proportional to the rate of cell killing, but efficacy was found to be significantly subdued at 0.5 mg/L and less dependent on the bacterial density. The bactericidal efficiency was higher at alkaline pH of 8 or above as compared to neutral and slightly acidic pH of 7 and 6.5 respectively. The disinfection kinetic curves followed a biphasic pattern of rapid inactivation within the initial 2 min which were followed by a tailing even in the presence of residual biocide. The curves were adequately described by the Cavg Hom model. Transmission Electron Microscopy images of the bacteria cells exposed to lethal concentrations of ClO2 indicated very little observable morphological damage to the outer membranes of the cells. ClO2 however was found to increase the permeability of the outer and cytoplasmic membranes leading to the leakage of membrane components such as 260 nm absorbing materials and inhibiting the activity of the intracellular enzyme β-D-galactosidase. It is suggested that the disruption of the cytoplasmic membrane and subsequent efflux of intracellular components result in the inactivation of the Gram-negative bacteria.

  19. Occurrence of brominated disinfection byproducts in the air and water of chlorinated seawater swimming pools.

    Science.gov (United States)

    Manasfi, Tarek; Temime-Roussel, Brice; Coulomb, Bruno; Vassalo, Laurent; Boudenne, Jean-Luc

    2017-05-01

    An undesirable consequence of disinfection is the formation of chemical contaminants known as disinfection byproducts (DBPs). Chronic exposure to DBPs has been linked to adverse health effects. The occurrence of DBPs in chlorinated pools filled with seawater (such as thalassotherapy pools and pools in spas) has received little attention so far. The present study evaluated the speciation and levels of disinfection byproducts in indoor swimming pools filled with seawater and treated with chlorine. Water and air samples were collected from three indoor swimming pools located in Southern France. Several classes of DBPs including trihalomethanes, haloacetic acids, haloacetonitriles, and trihaloacetaldehydes were analyzed in water. Halogenated volatile organic compounds were analyzed in air. Extractable organic halides (EOX) contents were determined using combustion/micro-coulometry system. The speciation of DBPs identified in the three pools was predominantly brominated. The mean (arithmetic) concentration of bromoform, dibromoacetic acid, tribromoacetic acid, dibromoacetonitrile and bromal hydrate in the three pools was 79.2, 72.9, 59.9, 26.9 and 10.0μg/L, respectively. By weight, HAAs represented the most abundant chemical class followed by THMs. In air, bromoform was the most abundant THM occurring at a mean concentration of 133.2μg/m(3) in the three pools. The mean EOX level was 706μgCl(-)/L for the three pools. In average, the quantified DBPs accounted for only 14% of EOX, thus 86% of EOX remained unknown. Further research is warranted to identify the unknown DBPs. Copyright © 2017 Elsevier GmbH. All rights reserved.

  20. Alternative Electrode Materials and Ceramic Filter Minimize Disinfection Byproducts in Point-of-Use Electrochemical Water Treatment

    Science.gov (United States)

    Yoon, Yeojoon; Jung, Youmi; Kwon, Minhwan; Cho, Eunha; Kang, Joon-Wun

    2013-01-01

    Abstract Effects of various electrodes and prefiltration to minimize disinfection byproducts (DBPs) in electrochemical water disinfection was evaluated. The target microorganism, Escherichia coli O157:H7, was effectively inactivated even applying a solar-charged storage battery for the electrolysis process. Extent of microbial inactivation decreased with lower water temperature and higher pH in the free chlorine disinfection system. The RuO2/Ti electrode was most efficient because it produced the lowest concentration of chlorate and the highest generation of free chlorine. Prefiltration using a ceramic filter inhibited formation of halogenated DBPs because it removed precursors of DBPs. For safe point-of-use water treatment, the use of a hybrid prefiltration stage with the electrolysis system is strongly recommended to reduce risks from DBPs. The system is particularly suited to use in developing regions. PMID:24381482

  1. APPLICATION OF SOLID PHASE MICROEXTRACTION GC/MS TO THE CHARACTERIZATION OF HYDROPHILIC DISINFECTION BY-PRODUCTS IN WATER

    Science.gov (United States)

    The U.S. Environmental Protection Agency has given high priority to research aimed at developing methods to extract hydrophilic disinfection by-products (DBPs) from drinking water. Public water supplies are treated with a variety of chemicals aimed at reducing or eliminating inf...

  2. Reproductive toxicity of a mixture of regulated drinking-water disinfection by-products in a multigenerational rat bioassay

    Science.gov (United States)

    BACKGROUND:Trihalomethanes (THMs) and haloaretic acids (HAAs) are regulated disinfection by-products (DBPs); their joint reproductive toxicity in drinking water is unknown.OBJECTIVE: We aimed to evaluate a drinking water mixture of the four regulated THMs and five regulated HAAs ...

  3. Assessment of bismuth thiols and conventional disinfectants on drinking water biofilms.

    Science.gov (United States)

    Codony, F; Domenico, P; Mas, J

    2003-01-01

    Biofilms in water distribution systems represent a far more significant reservoir of micro-organisms than the water phase. Biofilms are (i) resistant to disinfectants, (ii) nuclei for microbial regrowth, (iii) a refuge for pathogens, (iv) accompanied by taste and odour problems, and (v) corrode surfaces. The effects of the current strategies for disinfection of drinking water systems in large buildings (chlorination, copper and silver ionization, and hyper-heating) were compared with a new generation of bismuth thiol (BT) biocides. Multispecies biofilms were treated with 0.8 mg l(-1) of free chlorine, 400 and 40 microg l(-1) of copper and silver ions, respectively, at 55 and 70 degrees C, and bismuth-2,3-dimercaptopropanol (BisBAL). Furthermore, the effect of combined heat and BisBAL on planktonic cell viability was examined in monoculture using Escherichia coli suspensions. Inactivation rates for BisBAL were similar to copper-silver ions, where the effects were slower than for free chlorine or temperature. The BisBAL effect on E. coli monocultures was augmented greatly by increasing temperatures. Like copper-silver ions, BTs show more persistent residual effects than chlorine and hyper-heating in water systems. BT efficiency increased with temperature. Like copper-silver ions, BT action is relatively slow. BT presents a new approach to containing water biofilms. BT action is not as rapid, but is more thorough than chlorine, and less caustic. BTs may also be more efficacious in hot water systems. At sub-minimum inhibition concentration levels, BTs uniquely inhibit bacterial exopolysaccharide, thereby retarding biofilm formation. Thus, the combination of bactericidal and residual effects may prevent slime build-up in hot water systems.

  4. Disinfection action of electrostatic versus steric-stabilized silver nanoparticles on E. coli under different water chemistries.

    Science.gov (United States)

    Fauss, Emma K; MacCuspie, Robert I; Oyanedel-Craver, Vinka; Smith, James A; Swami, Nathan S

    2014-01-01

    The capping layer stabilizing silver nanoparticles (AgNPs) affects its aggregation, dissolution, and net disinfection action, especially under conditions of varying water composition, such as, pH, ionic strength and organic matter content. Herein, we correlate the silver ion (Ag(+)) release and reactive oxygen species (ROS) generation rates for AgNPs of varying functionalization to their net disinfection coefficient on Escherichia coli, under conditions of differing water chemistries. For electrostatically stabilized citrate-capped AgNPs, the rate of ROS generation, as measured using a fluorescent dye, is found to dominate over that of Ag(+) release, especially for smaller sized AgNP suspensions (~10nm) at low pH (~6.2). For these AgNPs, the ROS disinfection mechanism is confirmed to dominate net disinfection action, as measured by the live/dead assay, especially at low levels of organic matter. Steric stabilization of AgNPs by protein or starch-capped layers enables disinfection through reducing AgNP aggregation and promoting silver dissolution over ROS generation. We suggest the involvement of protons and dissolved oxygen in causing the independent formation of Ag(+) and ROS, regardless of the AgNP capping layer. While protein-capping layers effectively stabilize AgNPs, the generated ROS is likely dissipated by interference with the bulky capping layer, whereas the interference is lower with citrate-capping layers. Steric stabilization of AgNPs enables disinfection within a wide range of water chemistries, whereas effective disinfection can occur under electrostatic stabilization, only at low NaCl (<1 mmol/L) and organic matter (<5 mg/L) levels. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Demonstration of the Enhanced Disinfection of E. coli Water Contamination by Associated Solar Irradiation with Potassium Persulfate.

    Science.gov (United States)

    Ghanizadeh, Ghader; Naseri Ara, Ali; Esmaili, Davoud; Masoumbeigi, Hossein

    2015-10-01

    Tremendous amount of researches have investigated the issue of water photodisnfection. The aim of this research is to illustrate the influences of bacterial density, turbidity, exposure time and potassium persulfate (KPS) dosage on the efficacy of associated solar disinfection (SODIS) with KPS for E. coli (ATCC: 25922) eradication as an efficient and inexpensive process. Desired bacterial density and turbidity was achieved by spiking of 0.5 Mc Farland (1.5×10(8) cell/ml) and sterile soil slurry in 1 liter of the commercially bottled water. The highest value of UVA solar irradiation measured at 13.30 p.m was 5510 μW/Cm(2). Increase of bacterial density from 1000 to 1500 cell/ml led to an increase in disinfection lapse time, except in 2 mMol/l KPS. Spiking of 0.1 mMol/l of KPS was not effective; however, increase of KPS dosage from 0.1 mMol/l to 0.7, 1.5 and 2 mMol/l led to the enhancement of disinfection time from 4 h to 3 h and 1 h, respectively. For bacterial density of 1000 cell/ml, increasing KPS dosage up to 0.7 mMol/l had no improved effect; however, beyond this dosage the disinfection time decreased to 1 h. Without KPS and up to 150 NTU within 4 h exposure time, E. coli disinfection was completed. In 2 mMol/l KPS and 1000 and 1500 cell/ml, the 2 h contact time was sufficient up to 150 and 100 NTU, respectively; moreover, complete disinfection was not achieved at higher turbidity. Association of KPS with SODIS can lead to decreasing of water disinfection time.

  6. Development and evaluation of a reflective solar disinfection pouch for treatment of drinking water.

    Science.gov (United States)

    Walker, D Carey; Len, Soo-Voon; Sheehan, Brita

    2004-04-01

    A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles. The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period. These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials.

  7. MULTISPECTRAL IDENTIFICATION OF CHLORINE DIOXIDE DISINFECTION BY-PRODUCTS IN DRINKING WATER

    Science.gov (United States)

    This paper discusses the identification of organic disinfection by-products (DBPs) at a pilot plant in Evansville, Indiana, that uses chlorine dioxide as a primary disinfectant. nconventional multispectral identification techniques (gas chromatography combined with high and low r...

  8. Evaluation of Handheld Assays for the Detection of Ricin and Staphylococcal Enterotoxin B in Disinfected Waters

    Directory of Open Access Journals (Sweden)

    Mary Margaret Wade

    2011-01-01

    Full Text Available Development of a rapid field test is needed capable of determining if field supplies of water are safe to drink by the warfighter during a military operation. The present study sought to assess the effectiveness of handheld assays (HHAs in detecting ricin and Staphylococcal Enterotoxin B (SEB in water. Performance of HHAs was evaluated in formulated tap water with and without chlorine, reverse osmosis water (RO with chlorine, and RO with bromine. Each matrix was prepared, spiked with ricin or SEB at multiple concentrations, and then loaded onto HHAs. HHAs were allowed to develop and then read visually. Limits of detection (LOD were determined for all HHAs in each water type. Both ricin and SEB were detected by HHAs in formulated tap water at or below the suggested health effect levels of 455 ng/mL and 4.55 ng/mL, respectively. However, in brominated or chlorinated waters, LODs for SEB increased to approximately 2,500 ng/mL. LODs for ricin increased in chlorinated water, but still remained below the suggested health effect level. In brominated water, the LOD for ricin increased to approximately 2,500 ng/mL. In conclusion, the HHAs tested were less effective at detecting ricin and SEB in disinfected water, as currently configured.

  9. Community challenges when using large plastic bottles for Solar Energy Disinfection of Water (SODIS).

    Science.gov (United States)

    Borde, Preeti; Elmusharaf, Khalifa; McGuigan, Kevin G; Keogh, Michael B

    2016-09-05

    Communities living in developing countries as well as populations affected by natural or man-made disasters can be left at great risk from water related diseases, especially those spread through the faecal-oral route. Conventional water treatments such as boiling and chlorination can be effective but may prove costly for impoverished communities. Solar water disinfection (SODIS) has been shown to be a cheap and effective way for communities to treat their water. The exposure to sunlight is typically carried out in small volume plastic beverage bottles (up to 2 l). Given the water requirements of consumption and basic personal hygiene, this may not always meet the needs of communities. Recent work has shown 19-L plastic water dispenser containers to be effective SODIS reactors, comparable in efficacy to PET bottles. In this paper we outline the need for studying SODIS in large volumes and discuss 4 main associated challenges. Apart from clean water needed for consumption, access to adequate water is essential for sanitation and hygiene. Contamination of treated water through unwashed hands or vessels contributes heavily to the spread of water borne pathogens in communities. Traditional water treatments such as boiling and chlorination can be effective but may prove financially burdensome for low income communities. SODIS in large vessels could be used as a simple method to meet water requirements in low income and disaster affected populations. However, there have been some concerns associated with the conventional SODIS method; we identify the main ones to be: (1) cold or cloudy weather; (2) the fear of leaching in plastic bottles; (3) water turbidity, and; (4) community acceptance. The application of SODIS in large bottles like WDCs has the potential to be an efficient and cost effective method of disinfecting water, either for consumption until more rigorous water treatments can be put in place, or for sanitation and hygiene to curb the spread of fecal

  10. Community challenges when using large plastic bottles for Solar Energy Disinfection of Water (SODIS

    Directory of Open Access Journals (Sweden)

    Preeti Borde

    2016-09-01

    Full Text Available Abstract Background Communities living in developing countries as well as populations affected by natural or man-made disasters can be left at great risk from water related diseases, especially those spread through the faecal-oral route. Conventional water treatments such as boiling and chlorination can be effective but may prove costly for impoverished communities. Solar water disinfection (SODIS has been shown to be a cheap and effective way for communities to treat their water. The exposure to sunlight is typically carried out in small volume plastic beverage bottles (up to 2 l. Given the water requirements of consumption and basic personal hygiene, this may not always meet the needs of communities. Recent work has shown 19-L plastic water dispenser containers to be effective SODIS reactors, comparable in efficacy to PET bottles. In this paper we outline the need for studying SODIS in large volumes and discuss 4 main associated challenges. Discussion Apart from clean water needed for consumption, access to adequate water is essential for sanitation and hygiene. Contamination of treated water through unwashed hands or vessels contributes heavily to the spread of water borne pathogens in communities. Traditional water treatments such as boiling and chlorination can be effective but may prove financially burdensome for low income communities. SODIS in large vessels could be used as a simple method to meet water requirements in low income and disaster affected populations. However, there have been some concerns associated with the conventional SODIS method; we identify the main ones to be: (1 cold or cloudy weather; (2 the fear of leaching in plastic bottles; (3 water turbidity, and; (4 community acceptance. Summary The application of SODIS in large bottles like WDCs has the potential to be an efficient and cost effective method of disinfecting water, either for consumption until more rigorous water treatments can be put in place, or for

  11. Boiling of simulated tap water: effect on polar brominated disinfection byproducts, halogen speciation, and cytotoxicity.

    Science.gov (United States)

    Pan, Yang; Zhang, Xiangru; Wagner, Elizabeth D; Osiol, Jennifer; Plewa, Michael J

    2014-01-01

    Tap water typically contains numerous halogenated disinfection byproducts (DBPs) as a result of disinfection, especially of chlorination. Among halogenated DBPs, brominated ones are generally significantly more toxic than their chlorinated analogues. In this study, with the aid of ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry by setting precursor ion scans of m/z 79/81, whole spectra of polar brominated DBPs in simulated tap water samples without and with boiling were revealed. Most polar brominated DBPs were thermally unstable and their levels were substantially reduced after boiling via decarboxylation or hydrolysis; the levels of a few aromatic brominated DBPs increased after boiling through decarboxylation of their precursors. A novel adsorption unit for volatile total organic halogen was designed, which enabled the evaluation of halogen speciation and mass balances in the simulated tap water samples during boiling. After boiling for 5 min, the overall level of brominated DBPs was reduced by 62.8%, of which 39.8% was volatilized and 23.0% was converted to bromide; the overall level of chlorinated DBPs was reduced by 61.1%, of which 44.4% was volatilized and 16.7% was converted to chloride; the overall level of halogenated DBPs was reduced by 62.3%. The simulated tap water sample without boiling was cytotoxic in a chronic (72 h) exposure to mammalian cells; this cytotoxicity was reduced by 76.9% after boiling for 5 min. The reduction in cytotoxicity corresponded with the reduction in overall halogenated DBPs. Thus, boiling of tap water can be regarded as a "detoxification" process and may reduce human exposure to halogenated DBPs through tap water ingestion.

  12. Progressive Increase in Disinfection By-products and Mutagenicity from Source to Tap to Swimming Pool and Spa Water: Impact of Human Use

    Science.gov (United States)

    Pools and spas are enjoyed throughout the world for exercise and relaxation. However, there are no previous studies on mutagenicity of disinfected spa (hot tub) waters or comprehensive identification of disinfection byproducts (DBPs) formed in spas. Using 28 water samples from ...

  13. The potential of solar water disinfection as a household water treatment method in peri-urban Zimbabwe

    Science.gov (United States)

    Murinda, Sharon; Kraemer, Silvie

    The potential for reducing diarrhoea morbidity and improving the health status of children in developing countries using solar water disinfection (SODIS) has been demonstrated in past research. A baseline survey was conducted to explore the feasibility and necessity of introducing SODIS in peri-urban communities of Zimbabwe. The survey sought to establish drinking water quality in these areas and to determine the health and hygiene beliefs as well as practices related to water handling in the household. Microbiological water quality tests and personal interviews were carried out in Epworth township and Hopley farm, two peri-urban areas near the capital of Zimbabwe, Harare. These two areas are among the poorest settlements around Harare with 80% of inhabitants being informal settlers. Community meetings were held to introduce solar water disinfection prior to the survey. This was followed by administration of questionnaires, which aimed to investigate whether the community had ever heard about SODIS, whether they were practicing it, other means that were being used to treat drinking water as well as health and hygiene beliefs and practices. It was found out that most households cannot afford basic water treatment like boiling as firewood is expensive. People generally reported that the water was not palatable due to objectionable odour and taste. Microbiological water quality tests proved that drinking water was contaminated in both areas, which makes the water unsafe for drinking and shows the necessity of treatment. Although the majority of people interviewed had not heard of SODIS prior to the interview, attitudes towards its introduction were very positive and the intention to do SODIS in the future was high. Amongst the ones who had heard about SODIS before the study, usage was high. Plastic PET bottles, which were used for the SODIS experiments are currently unavailable and this has been identified as a potential hindrance to the successful implementation of

  14. [Microbiological studies of the significance of natural and simulated water transmission in the evaluation of UV plants for water disinfection].

    Science.gov (United States)

    Leuker, G; Hingst, V

    1990-10-01

    The efficiency of UV-irradiation for water disinfection was tested using an UV-plant with constant flow between 0.7 and 11.5 m3/h. Within the range of water transmission (254 nm) between 40% and 98% (1 cm), which naturally was found in tap water, water from the Neckar river and biologically treated sewage water in an amount of 96%, 78% and ca. 60%, simulation was performed by artificial addition of fluorescein to demineralized water. Data obtained show similar results for the reduction of E. faecium and C. albicans, which were used as test strains. The investigation show no major discrepancies in the range of transmission from 80-96%, which is relevant for tap water disinfection. Water transmission at 254 nm was confirmed as important factor for UV-irradiation. Also found suitable was fluorescein for simulation of the natural water transmission without affecting the test strains. Thus UV-sensitivity of test strains could be detected by combination of flow rate and simulated water transmission using fluorescein. P. aeruginosa and E. coli were found to be more UV-sensitive than S. enteritidis and S. marcescens. UV-resistance increased on the scale from E. faecium, S. aureus, M. luteus up to C. albicans. The efficiency of an UV-plant can be experimentally defined by a specific combination of flow rate (up to a certain amount) and water transmission. Thus the question can be answered whether and UV-plant is able to fulfill the specific requirements in use. These results, regarding the artificial variation of transmission values, are to be considered important for the specification of an additional measure of safety for minimal irradiation exposure times.

  15. Amoebae in domestic water systems: resistance to disinfection treatments and implication in Legionella persistence.

    Science.gov (United States)

    Thomas, V; Bouchez, T; Nicolas, V; Robert, S; Loret, J F; Lévi, Y

    2004-01-01

    Monitoring of microbial changes during and after application of various disinfection treatments in a model domestic water system. A pilot-scale domestic water system consisting of seven galvanized steel re-circulation loops and copper dead legs was constructed. Culture techniques, confocal laser scanning microscopy after fluorescent in situ hybridization and viability staining with the BacLight LIVE/DEAD kit were used for planktonic and biofilm flora monitoring. Before starting the treatments, the system was highly contaminated with Legionella pneumophila and biofilm populations mainly consisted of beta-proteobacteria. In the water and the biofilm of the loops, continuous application of chlorine dioxide (0.5 mg l(-1)), or chlorine (2.5 mg l(-1)) were very effective in reducing the microbial flora, including L. pneumophila. Heterotrophic bacteria, although strongly reduced, were still detectable after ozone application (0.5 mg l(-1)), whereas with monochloramine (0.5 mg l(-1)) and copper-silver ionization (0.8/0.02 mg l(-1)), the contamination remained significantly higher. Monochloramine and copper-silver did not remove the biofilm. During copper-silver application, Legionella re-growth was observed. Only chlorine dioxide led to detectable effects in the dead leg. Amoebae could not be eliminated, and after interrupting the treatments, L. pneumophila quickly recovered their initial levels, in all cases. Chlorine dioxide, applied as a continuous treatment, was identified in this study as the most efficient for controlling L. pneumophila in a domestic water system. Chlorine dioxide showed a longer residual activity, leading to improved performance in the dead leg. Amoebae resisted to all the treatments applied and probably acted as reservoirs for L. pneumophila, allowing a quick re-colonization of the system once the treatments were interrupted. Control of microbial contamination requires maintenance of a constant disinfectant residual throughout the water system

  16. Water disinfection with solar radiation; Desinfeccion del agua con radiacion solar

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Alejandra; Cortes, Juana E; Rodriguez, Miriam; Mundo, Alfredo; Vazquez, Sandra [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico); Estrada, Claudio A [Centro de Investigacion en Energia, Temixco, Morelos (Mexico)

    2000-07-01

    Water disinfection by exposure to solar radiation is a low cost and easy application option to rural communities. The treatment of water can be done using plastic bags or plastic bottles of two litters setting on a reflective material. The efficient of the plastic bottles is lower than the one plastic bags, but the plastic bottles have a much better control of the treated water avoiding its recontamination. In order to increase the efficiency of disinfection using plastic bottles, two solar concentrators, using flat mirrors, were designed and built. Effluent water from a treatment plant of residual waters was used for the testing. Several comparison were carried out taking into account the position of the concentrators, the transparency of the bottles and the bags. The results show that using the concentrator that adjust its position to the sun every hour, a 100% disinfection is obtained in 4 hours of direct exposure to the sun rays in a sunny day. The period of time can be reduced up to 2 hours, if instead using transparent bottles, the bottles are black painted at their bottom half. With these results, the basis to design a cheap concentrator of easy construction to be used in rural communities have been settle. [Spanish] La desinfeccion del agua por exposicion a la luz solar fotodesinfeccion es una opcion de bajo costo y facil aplicacion para las comunidades rurales. El tratamiento puede llevarse a cabo utilizando bolsas o botellas de plastico transparente de dos litros de capacidad colocadas sobre un material reflejante. Las botellas son menos eficientes que las bolsas, pero permiten un mejor control del agua tratada evitando su recontaminacion. Para aumentar la eficiencia de la desinfeccion utilizando las botellas, se disenaron y construyeron dos concentradores solares de espejos planos que permitieron disminuir el tiempo de exposicion requerido cuando se utilizan estas. Para las pruebas de desinfeccion se utilizo agua del efluente de una planta de tratamiento

  17. Factors affecting the diffusion of solar water disinfection: a field study in Bolivia.

    Science.gov (United States)

    Heri, Simone; Mosler, Hans-Joachim

    2008-08-01

    This study examines a broad array of theory-based factors derived from diffusion research that affect the current and intended use of solar water disinfection (SODIS), a simple, low-cost technology for treating drinking water at the household level. The perceived attributes of an innovation, the nature of the social system in which it is diffused, the extent of change agents' promotional efforts in diffusing it, and the nature of the communication channels used were operationalized by 16 variables. The aim of the study is to determine the influence of each factor and its predictive power. Eight areas in Bolivia were visited, and 644 families were interviewed on the basis of a structured questionnaire. Simultaneous multiple regression analysis showed that 9 of the 16 factors derived from diffusion research contributed significantly to predicting the current use of SODIS. The implications of the findings for customizing future SODIS diffusion activities are outlined.

  18. Control of disinfection by-products in canned vegetables caused by water used in their processing.

    Science.gov (United States)

    Cardador, Maria Jose; Gallego, Mercedes

    2017-01-01

    Canned vegetables come into contact with sanitizers and/or treated water in industry during several steps (namely washing, sanitising, blanching and filling with sauces or brine solutions) and therefore they can contain disinfection by-products - DBPs). This study focused on the occurrence of trihalomethanes (THMs) and haloacetic acids (HAAs) in a wide variety of canned vegetables (75 samples). For each vegetable, the edible solid and liquid phases of the package were separated and analysed individually. DBPs can be present in both solid (up to eight species) and liquid (up to 11 species) phases, their levels being higher in liquid ones. Volatile THMs predominate in the edible solid phase (up to four species), while HAAs do so in the liquid phase (up to five species) according to their ionic and non-volatile nature. The lowest concentrations of DBPs were found in tomatoes because they were often preserved in their own juice, without water.

  19. Secondary formation of disinfection by-products by UV treatment of swimming pool water

    DEFF Research Database (Denmark)

    Spiliotopoulou, Aikaterini; Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

    2015-01-01

    be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence...... trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment. The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates......Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile...

  20. Solar Water disinfection for human consumption; Desinfeccao Solar de Agua para consumo humano

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, A.; Vilar, V.; Boaventura, R.

    2008-07-01

    In this work a pilot plant with 0.59 m{sup 2} of solar collectors has been used for studying the disinfection by solar photo catalysis of waters contaminated with Escherichia coli, Enterococcus faecal or humic acids. the results obtained showed a higher resistance of Enterococcus to the photo catalytic treatment ([TiO{sub 2}] =50 mg/L) compared with E. coli, being necessary a higher amount of UV energy for killing them, using an initial bacteria concentration of 1x10{sup 5} CFU/mL. For the treatment of water contaminated with humic acids was applied 20 kJ UV/L to reduce the TOC concentration from 6.9 mg/L to 1 mg/L. (Author)

  1. Virus Disinfection in Water by Biogenic Silver Immobilized in Polyvinylidene Fluoride Membranes

    Energy Technology Data Exchange (ETDEWEB)

    B De Gusseme; T Hennebel; E Christiaens; H Saveyn; K Verbeken; J Fitts; N Boon; W Vertraete

    2011-12-31

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sup 0}{sub powder} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {mu}g L{sub -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {mu}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale.

  2. Disinfection characteristics of the dissolved organic fractions at several stages of a conventional drinking water treatment plant in Southern China.

    Science.gov (United States)

    Zhao, Zhen-Ye; Gu, Ji-Dong; Li, Hai-Bo; Li, Xiao-Yan; Leung, Kenneth Mei-Yee

    2009-12-30

    Dissolved organic matter (DOM) influences many aspects of drinking water treatment, including the formation of harmful disinfection by-products (DBPs) when disinfectants are applied. DOM was isolated and fractionated using membrane ultra-filtration (UF) and reverse osmosis (RO) to eight individual fractions based on molecular weight cut-offs from a conventional surface water treatment plant (WTP) in Guangzhou of PR China. Molecular weights of these eight fractions were further calibrated using high performance size exclusion chromatography (HPSEC) and they ranged from 0.36 to 182.6 kDa. Fractions with molecular weight membrane and RO were the major ones in all four stages of the water treatment processes; both ZM-500 and YM-100 membranes showed the highest removal efficiency when coupling with conventional coagulation and sedimentation processes. The elemental analysis showed that YC-05 fraction had greater polarity and aromaticity than any of the others. Furthermore, disinfection characteristics and trihalomethane formation potential (THMFP) were determined for all DOM fractions obtained in this study. YC-05 fraction was the major precursor for trihalomethane (THMs) formation among the samples tested and could be removed effectively by particulate activated carbon (PAC) adsorption. RO fraction could not be removed by PAC adsorption and, as a result, consumed more chlorine in the disinfection process. The results suggested that advanced drinking water treatment should focus on the removal of low molecular weight DOM in the source water.

  3. Disinfection of titanium dioxide nanotubes using super-oxidized water decrease bacterial viability without disrupting osteoblast behavior

    Energy Technology Data Exchange (ETDEWEB)

    Beltrán-Partida, Ernesto [Department of Biomaterials, Dental Materials and Tissue Engineering, Faculty of Dentistry Mexicali, Autonomous University of Baja California, Av. Zotoluca and Chinampas St., 21040 Mexicali, Baja California (Mexico); Department of Corrosion and Materials, Engineering Institute, Autonomous University of Baja California, Blvd. Benito Juarez and Normal St., 21280 Mexicali, Baja California (Mexico); Valdez-Salas, Benjamín, E-mail: benval@uabc.edu.mx [Department of Corrosion and Materials, Engineering Institute, Autonomous University of Baja California, Blvd. Benito Juarez and Normal St., 21280 Mexicali, Baja California (Mexico); Escamilla, Alan; Curiel, Mario [Department of Corrosion and Materials, Engineering Institute, Autonomous University of Baja California, Blvd. Benito Juarez and Normal St., 21280 Mexicali, Baja California (Mexico); Valdez-Salas, Ernesto [Ixchel Medical Centre, Av. Bravo y Obregón, 21000 Mexicali, Baja California (Mexico); Nedev, Nicola [Department of Corrosion and Materials, Engineering Institute, Autonomous University of Baja California, Blvd. Benito Juarez and Normal St., 21280 Mexicali, Baja California (Mexico); Bastidas, Jose M. [National Centre for Metallurgical Research, CSIC, Av. Gregorio del Amo 8, 28040 Madrid (Spain)

    2016-03-01

    Amorphous titanium dioxide (TiO{sub 2}) nanotubes (NTs) on Ti6Al4V alloy were synthesized by anodization using a commercially available super-oxidized water (SOW). The NT surfaces were sterilized by ultraviolet (UV) irradiation and disinfected using SOW. The adhesion and cellular morphology of pig periosteal osteoblast (PPO) cells and the behavior of Staphylococcus aureus (S. aureus) cultured on the sterilized and disinfected surfaces were investigated. A non-anodized Ti6Al4V disc sterilized by UV irradiation (without SOW) was used as control. The results of this study reveal that the adhesion, morphology and filopodia development of PPO cells in NTs are dramatically improved, suggesting that SOW cleaning may not disrupt the benefits obtained by NTs. Significantly decreased bacterial viability in NTs after cleaning with SOW and comparing with non-cleaned NTs was seen. The results suggest that UV and SOW could be a recommendable method for implant sterilization and disinfection without altering osteoblast behavior while decreasing bacterial viability. - Highlights: • The effect of super-oxidized water cleaning was studied on Ti6Al4V nanotubes. • Super oxidized-water cleaning caused a decline in S. aureus viability. • Osteoblast behavior was not disrupted after super-oxidized water disinfection. • Super-oxidized water is suggested as a cleaning protocol for TiO{sub 2} nanotubes.

  4. Solar water disinfection (SODIS); Traitement de l'eau par l'energie solaire

    Energy Technology Data Exchange (ETDEWEB)

    Wegelin, M. [Water Treatment, EAWAG/SANDEC, Duebendorf (Switzerland)

    1998-07-01

    Solar water disinfection uses solar energy to inactivate and destroy pathogenic microorganisms present in the water. The use of solar energy, which is universally available and free of charge. is the basis of this low-cost technology to be applied on household level for the treatment of small quantifies of drinking water. The treatment basically consists in filling transparent containers with water and expose them to full sunlight for several hours. Extensive laboratory and field tests carried out by EAWAG and its partners revealed that synergies induced by the combined application of radiation and thermal treatment have a significant effect on the die-off rate of the microorganisms. For example, field tests demonstrated that the concentration of Vibrio cholerae is reduced by a factor of 1000 during an exposure time of 30 minutes and a water temperature of 50 deg.C. The use of half-side blackened bottles or of plastic bags is a simple application of the batch process which. however, limits the daily capacity to the volume of water stored in the containers. Continuous-flow systems consist of solar collectors and heat exchangers which significantly increase the use of the available solar energy and, thereby, also the output of treated water. (author)

  5. Disinfectant effect of chloride treatment on swimming pool water and water intended for human consumption in the Balearic Islands (Spain); Efecto desinfectante del tramiento con cloro en aguas de piscinas y aguas destinadas al consumo umano en Baleares

    Energy Technology Data Exchange (ETDEWEB)

    Sastre-Coll, A.; Duran Abad, M.; Rosello Jimenez, C.; Monegal, M. R.; Adrover Julia, M. M.; Baberhauserhaide, K.; Gonzalez Ensenat, M.; Vidal Oliver, M.; Arderiu Costas, E.; Lliteras Riutort, R. M.; Menas Ribas, I.; Reviriego Riudavets, B.; Pozo fernandez, M.; Mir Massanet, F.

    2008-07-01

    The disinfectant effect of chlorine treatments on swimming pool water and water intended for human consumption in the Balearic Islands was assessed. the results show a correct disinfection in drinking water with 0,3 mg/l of free chlorine concentration. On the other hand 0,5 and 2.0 mg/l of free chlorine are needed to disinfect the swimming pool water during low and high tourist season respectively. The lack of the disinfectant effect of smaller free chlorine doses seems to be related to the pH values of the water analysed. (Author)

  6. Solar disinfection improves drinking water quality to prevent diarrhea in under-five children in sikkim, India.

    Science.gov (United States)

    Rai, Bb; Pal, Ranabir; Kar, Sumit; Tsering, Dechen C

    2010-09-01

    Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children. To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method. This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1(st) May 2007 to 30(th) November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET) bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance. After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS) users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant. In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in PET bottles in the intervention group.

  7. Toxicity of drinking water disinfection byproducts: cell cycle alterations induced by the monohaloacetonitriles.

    Science.gov (United States)

    Komaki, Yukako; Mariñas, Benito J; Plewa, Michael J

    2014-10-07

    Haloacetonitriles (HANs) are a chemical class of drinking water disinfection byproducts (DBPs) that form from reactions between disinfectants and nitrogen-containing precursors, the latter more prevalent in water sources impacted by algae bloom and municipal wastewater effluent discharge. HANs, previously demonstrated to be genotoxic, were investigated for their effects on the mammalian cell cycle. Treating Chinese hamster ovary (CHO) cells with monoHANs followed by the release from the chemical treatment resulted in the accumulation of abnormally high DNA content in cells over time (hyperploid). The potency for the cell cycle alteration followed the order: iodoacetonitrile (IAN) > bromoacetonitrile (BAN) ≫ chloroacetonitrile (CAN). Exposure to 6 μM IAN, 12 μM BAN and 900 μM CAN after 26 h post-treatment incubation resulted in DNA repair; however, subsequent cell cycle alteration effects were observed. Cell proliferation of HAN-treated cells was suppressed for as long as 43 to 52 h. Enlarged cell size was observed after 52 h post-treatment incubation without the induction of cytotoxicity. The HAN-mediated cell cycle alteration was mitosis- and proliferation-dependent, which suggests that HAN treatment induced mitosis override, and that HAN-treated cells proceeded into S phase and directly into the next cell cycle. Cells with multiples genomes would result in aneuploidy (state of abnormal chromosome number and DNA content) at the next mitosis since extra centrosomes could compromise the assembly of bipolar spindles. There is accumulating evidence of a transient tetraploid state proceeding to aneuploidy in cancer progression. Biological self-defense systems to ensure genomic stability and to eliminate tetraploid cells exist in eukaryotic cells. A key tumor suppressor gene, p53, is oftentimes mutated in various types of human cancer. It is possible that HAN disruption of the normal cell cycle and the generation of aberrant cells with an abnormal number of

  8. Occurrence of nitrogenous and carbonaceous disinfection byproducts in drinking water distributed in Shenzhen, China.

    Science.gov (United States)

    Huang, Huang; Zhu, Haihui; Gan, Wenhui; Chen, Xue; Yang, Xin

    2017-12-01

    A 12-month sampling program was conducted throughout a drinking water distribution system in Shenzhen and the data from 251 samples provide a comprehensive picture of the spatial and seasonal variability of 17 species disinfection by-products (DBPs) in a city with subtropical monsoon climate. The carbonaceous disinfection by-product (C-DBPs) included four trihalomethanes (THMs), three trihaloacetaldehydes (THAs) and two haloketones (HKs). Their median concentrations over the entire period were 19.9 μg/L, 3.4 μg/L and 1.4 μg/L, respectively. The nitrogenous DBPs (N-DBPs) monitored were four haloacetonitriles (HANs) and four haloacetamides (HAcAms). Their median levels were 2.0 μg/L and 1.5 μg/L, respectively. Low levels of brominated DBP species (bromine substitution factors ≤ 0.5) were observed. The BSF of each DBP class followed the trend: THMs ≈ DHAcAms > DHANs > THAs. All the DBP concentrations showed clear seasonal variations with the highest average concentrations in spring. Correlation analyses showed that the THMs and CH levels in Shenzhen drinking water could be used as statistical indicators of the levels of unregulated N-DBPs (0.4 water in China, and provide an important reference data set for DBP occurrence in cities with a subtropical monsoon climate around the world. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Potential impacts of disinfection processes on elimination and deactivation of antibiotic resistance genes during water and wastewater treatment.

    Science.gov (United States)

    Dodd, Michael C

    2012-07-01

    Antibiotic resistance genes (ARGs), in association with antibiotic resistant bacteria (ARB), have been identified as widespread contaminants of treated drinking waters and wastewaters. As a consequence, concerns have been raised that ARB or ARG transport between aquatic compartments may enhance the spread of antibiotic resistance amongst non-resistant bacterial communities by means of horizontal gene transfer processes. Most often, discussion of horizontal gene transfer focuses on the probable role of conjugative plasmid or transposon exchange, which requires live ARB donor cells. Conventional water and wastewater disinfection processes generally provide highly effective means for mitigating the transport of live ARB; thereby minimizing risks of conjugative gene transfer. However, even if ARB present in a treated water are fully inactivated during a disinfection process, the possibility remains that intact remnants of DNA contained within the resulting cell debris could still confer resistance genotypes to downstream bacterial populations by means of natural transformation and/or transduction, which do not require live donor cells. Thus, a systematic evaluation of the capability of common disinfection technologies to ensure the destruction of bacterial DNA, in addition to pathogen inactivation, seems warranted. With that objective in mind, this review seeks to provide a concise introduction to the significance of ARB and ARG occurrence in environmental systems, coupled with a review of the role that commonly used water and wastewater disinfection processes may play in minimizing ARG transport and dissemination.

  10. Destruction of disinfection byproducts and their precursors in swimming pool water by combined UV treatment and ozonation

    DEFF Research Database (Denmark)

    Cheema, Waqas Akram; Kaarsholm, Kamilla Marie Speht; Andersen, Henrik Rasmus

    Both UV treatment and ozonation are used to reduce different types of disinfection byproducts (DBP) in swimming pools. UV treatment is most common as it is particularly efficient in removing the repulsive chlorine like smelling chloramines (combined chlorine). UV treatment of a pool water increased...

  11. Developmental toxicity of mixtures: the water disinfection by-products dichloro-, dibromo- and bromochloro acetic acid in rat embryo culture

    Science.gov (United States)

    The chlorination of drinking water results in production of numerous disinfection by-products (DBPs). One of the important classes of DBPs is the haloacetic acids. We have previously shown that the haloacetic acids (HAs), dichloro (DCA), dibromo (DBA) and bromochloro (BCA) acetic...

  12. Exposure to drinking water disinfection by-products and pregnancy loss.

    Science.gov (United States)

    Savitz, David A; Singer, Philip C; Herring, Amy H; Hartmann, Katherine E; Weinberg, Howard S; Makarushka, Christina

    2006-12-01

    Previous research has suggested that exposure to elevated levels of drinking water disinfection by-products (DBPs) may cause pregnancy loss. In 2000-2004, the authors conducted a study in three US locations of varying DBP levels and evaluated 2,409 women in early pregnancy to assess their tap water DBP concentrations, water use, other risk factors, and pregnancy outcome. Tap water concentrations were measured in the distribution system weekly or biweekly. The authors considered DBP concentration and ingested amount and, for trihalomethanes only, bathing/showering and integrated exposure that included ingestion. On the basis of 258 pregnancy losses, they did not find an increased risk of pregnancy loss in relation to trihalomethane, haloacetic acid, or total organic halide concentrations; ingested amounts; or total exposure. In contrast to a previous study, pregnancy loss was not associated with high personal trihalomethane exposure (> or =75 micro g/liter and > or =5 glasses of water/day) (odds ratio = 1.1, 95% confidence interval: 0.7, 1.7). Sporadic elevations in risk were found across DBPs, most notably for ingested total organic halide (odds ratio = 1.5, 95% confidence interval: 1.0, 2.2 for the highest exposure quintile). These results provide some assurance that drinking water DBPs in the range commonly encountered in the United States do not affect fetal survival.

  13. Effect of ozonation of swimming pool water on formation of volatile disinfection by-products - A laboratory study

    DEFF Research Database (Denmark)

    Hansen, Kamilla Marie Speht; Spiliotopoulou, Aikaterini; Cheema, Waqas Akram

    2016-01-01

    Ozonation experiments were performed using unchlorinated tap water used for filling municipal swimming pools, actual pool water and pool water polluted by addition of fresh tap water and artificial body fluid to evaluate ozone kinetics and water quality effects on formation of volatile disinfection...... was approximated 17-19 min in all samples. Subsequent chlorination revealed ozone removed reactivity of dissolved organic carbon toward chlorine for tap and polluted pool water, decreasing formation rate of trihalomethanes (TTHM). In pool water higher rates of TTHM formation was observed after the initial ozone...

  14. Characterization of organic matter and disinfection by-products in membrane backwash water from drinking water treatment.

    Science.gov (United States)

    Zhang, Lingling; Gu, Ping; Zhong, Zijie; Yang, Dong; He, Wenjie; Han, Hongda

    2009-09-15

    Two pilot-scale membrane plants were set up to produce drinking water, and membrane backwash water was discharged during the production process. This work studied the characteristics of dissolved organic matter (DOM) in membrane backwash water from submerged microfiltration (MBWS) and pressurized ultrafiltration (MBWP) both of which are coupled with the pre-coagulation process. The results showed that the two waters had similar molecular weight (MW) distributions. Dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP) in MBWS and MBWP were both mainly distributed in MW>30 kDa and MWwater (LRW, the raw water for the two pilot-scale membrane plants in this study), organic matter enriched in membrane backwash water was mainly in sizes of MW>30 kDa. In addition, organic matter with MW>10 kDa was higher in MBWP than in MBWS. The quality of membrane backwash water was influenced by the changes in LRW quality during different periods. The quality of membrane backwash water was worse in alga-laden period than in normal period and organic matter concentrations in MWmembrane backwash water was more reactive to form trihalomethanes (THMs) in the disinfection process. The variability of specific UV absorbance and THMFP/DOC was consistent in membrane backwash water.

  15. Fluence Rate in UV Photoreactor for Disinfection of Water: Isotropically Radiating Cylinder

    Directory of Open Access Journals (Sweden)

    Roman Ilinsky

    2014-01-01

    Full Text Available The calculation of fluence rate in the photochemical reactor using ultraviolet (UV radiation for disinfection of water for the case, when a cylinder of infinite length is used as a light source, has been considered. Such a cylinder is filled with an isotropically radiating medium. The dependence of the fluent rate on the diameter of the radiating cylinder has been analytically analyzed. The limiting case when the diameter of the radiating cylinder tends to zero has been considered and the notion of “effective interval” has been introduced. Based on this notion, the comparison of fluence rates for the cylinders of finite and infinite lengths has been performed. In the calculations of fluence rate, it is advisable to use the Chebyshev method for the operations of numerical integration.

  16. Thermal contribution to the inactivation of Cryptosporidium in plastic bottles during solar water disinfection procedures.

    Science.gov (United States)

    Gómez-Couso, Hipólito; Fontán-Sainz, María; Ares-Mazás, Elvira

    2010-01-01

    To determine the thermal contribution, independent of ultraviolet radiation, on the inactivation of Cryptosporidium parvum during solar water disinfection procedures (SODIS), oocysts were exposed for 4, 8, and 12 hours to temperatures recorded in polyethylene terephthalate bottles in previous SODIS studies carried out under field conditions. Inclusion/exclusion of the fluorogenic vital dye propidium iodide, spontaneous excystation, and infectivity studies were used to determine the inactivation of oocysts. There was a significant increase in the percentage of oocysts that took up propidium iodide and in the number of oocysts that excysted spontaneously. There was also a significant decrease in the intensity of infection elicited in suckling mice at the end of all exposure times. The results of the study demonstrate the importance of temperature in the inactivation of C. parvum oocysts during application of SODIS under natural conditions.

  17. What's in the pool? A comprehensive identification of disinfection by-products and assessment of mutagenicity of chlorinated and brominated swimming pool water

    NARCIS (Netherlands)

    Richardson, S.D.; Demarini, D.M.; Kogevinas, M.; Fernandez, P.; Marco, E.; Lourencetti, C.; Balleste, C.; Heederik, D.|info:eu-repo/dai/nl/072910542; Meliefste, K.; McKague, A.B.; Marcos, R.; Font-Ribera, L.; Grimalt, J.O.; Villanueva, C.M.

    2010-01-01

    BACKGROUND: Swimming pool disinfectants and disinfection by-products (DBPs) have been linked to human health effects, including asthma and bladder cancer, but no studies have provided a comprehensive identification of DBPs in the water and related that to mutagenicity. OBJECTIVES: We performed a

  18. ASCORBIC ACID TREATMENT TO REDUCE RESIDUAL HALOGEN-BASED OXIDANTS PRIOR TO THE DETERMINATION OF HALOGENATED DISINFECTION BYPRODUCTS IN POTABLE WATER

    Science.gov (United States)

    Treatment of potable water samples with ascorbic acid has been investigated as a means for reducing residual halogen-based oxidants (disinfectants)i.e., HOCl, Cl2, Brw and BrCl, prior to determination of EPA Method 551.1A and 551.1B analytes. These disinfection byproducts include...

  19. OXIDATIVE DNA DAMAGE FROM POTASSIUM BROMATE EXPOSURE IN LONG-EVANS RATS IS NOT ENHANCED BY A MIXTURE OF DRINKING WATER DISINFECTION BY-PRODUCTS

    Science.gov (United States)

    Public drinking water treated with chemical disinfectants contains a complex mixture of disinfection by-products (DBPs) for which the relative toxicity of the mixtures needs to be characterized to accurately assess risk. Potassium bromate (KBrO3) is a by-product from ozonation of...

  20. Solar light irradiation significantly reduced cytotoxicity and disinfection byproducts in chlorinated reclaimed water.

    Science.gov (United States)

    Lv, Xiao-Tong; Zhang, Xue; Du, Ye; Wu, Qian-Yuan; Lu, Yun; Hu, Hong-Ying

    2017-11-15

    Chlorinated reclaimed water is widely used for landscaping and recreational purposes, resulting in human exposure to toxic disinfection byproducts. Although the quality of chlorinated reclaimed water might be affected by sunlight during storage, the effects of solar light irradiation on the toxicity remain unknown. This study investigated the changes in cytotoxicity and total organic halogen (TOX) of chlorinated reclaimed water exposed to solar light. Irradiation with solar light for 12 h was found to significantly reduce the cytotoxicity of chlorinated reclaimed water by about 75%, with ultraviolet light being responsible for the majority of this reduction. Chlorine residual in reclaimed water tended to increase the cytotoxicity, and the synergy between solar light and free chlorine could not enhance the reduction of cytotoxicity. Adding hydroxyl radical scavengers revealed that the contribution of hydroxyl radical to cytotoxicity reduction was limited. Solar light irradiation concurrently reduced TOX. The low molecular weight (1 kDa) fraction was probably caused by photoconversion from high toxic TOX to low toxic TOX. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Disinfection byproduct formation resulting from settled, filtered, and finished water treated by titanium dioxide photocatalysis.

    Science.gov (United States)

    Mayer, Brooke K; Daugherty, Erin; Abbaszadegan, Morteza

    2014-12-01

    This study evaluated strategies targeting disinfection byproduct (DBP) mitigation using TiO2 photocatalysis with varying influent water quality. A Purifics Photo-CAT Lab reactor was used to assess total trihalomethane (TTHM) and haloacetic acid (HAA) formation as a function of photocatalytic treatment using water from a conventional coagulation/flocculation/sedimentation process, granular activated carbon filtration, and a DBP hot spot in the water distribution system. Regardless of influent water quality, photocatalysis reduced DBP precursors; however, low-energy limited photocatalysis (photocatalysis is not a suitable option when TTHMs and HAA5s are a concern, regardless of the level of pretreatment. Limited photocatalysis yields incomplete oxidation, wherein larger, more aromatic, humic organic compounds are broken into smaller molecular weight, less aromatic, and less humic moieties, which have considerable potential to produce DBPs. More complete mineralization of DBP precursors is obtained using extended photocatalysis (80-160 kW h m(-3)), which substantially decreases DBP precursors as well as TTHM and HAA5 concentrations. In order to balance DBP mitigation, energy, and chemical usage, targeted use of TiO2 photocatalysis is necessary in a water treatment train (e.g., extended photocatalysis at a distribution system hot spot, where the volumetrically high energy requirements may be justifiable). Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Excystation of Cryptosporidium parvum at temperatures that are reached during solar water disinfection.

    Science.gov (United States)

    Gómez-Couso, H; Fontán-Sainz, M; Fernández-Alonso, J; Ares-Mazás, E

    2009-04-01

    Species belonging to the genera Cryptosporidium are recognized as waterborne pathogens. Solar water disinfection (SODIS) is a simple method that involves the use of solar radiation to destroy pathogenic microorganisms that cause waterborne diseases. A notable increase in water temperature and the existence of a large number of empty or partially excysted (i.e. unviable) oocysts have been observed in previous SODIS studies with water experimentally contaminated with Cryptosporidium parvum oocysts under field conditions. The aim of the present study was to evaluate the effect of the temperatures that can be reached during exposure of water samples to natural sunlight (37-50 degrees C), on the excystation of C. parvum in the absence of other stimuli. In samples exposed to 40-48 degrees C, a gradual increase in the percentage of excystation was observed as the time of exposure increased and a maximum of 53.81% of excystation was obtained on exposure of the water to a temperature of 46 degrees C for 12 h (versus 8.80% initial isolate). Under such conditions, the oocyst infectivity evaluated in a neonatal murine model decreased statistically with respect to the initial isolate (19.38% versus 100%). The results demonstrate the important effect of the temperature on the excystation of C. parvum and therefore on its viability and infectivity.

  3. Solar radiation disinfection of drinking water at temperate latitudes: inactivation rates for an optimised reactor configuration.

    Science.gov (United States)

    Davies, C M; Roser, D J; Feitz, A J; Ashbolt, N J

    2009-02-01

    Solar radiation-driven inactivation of bacteria, virus and protozoan pathogen models was quantified in simulated drinking water at a temperate latitude (34 degrees S). The water was seeded with Enterococcus faecalis, Clostridium sporogenes spores, and P22 bacteriophage, each at ca 1x10(5) mL(-1), and exposed to natural sunlight in 30-L reaction vessels. Water temperature ranged from 17 to 39 degrees C during the experiments lasting up to 6h. Dark controls showed little inactivation and so it was concluded that the inactivation observed was primarily driven by non-thermal processes. The optimised reactor design achieved S90 values (cumulative exposure required for 90% reduction) for the test microorganisms in the range 0.63-1.82 MJ m(-2) of Global Solar Exposure (GSX) without the need for TiO2 as a catalyst. High turbidity (840-920 NTU) only reduced the S(90) value by 0.05). However, inactivation was significantly reduced for E. faecalis and P22 when the transmittance of UV wavelengths was attenuated by water with high colour (140 PtCo units) or a suboptimally transparent reactor lid (prob.SODIS type pasteurization were not produced, non-thermal inactivation alone appeared to offer a viable means for reliably disinfecting low colour source waters by greater than 4 orders of magnitude on sunny days at 34 degrees S latitude.

  4. Achieving long-term use of solar water disinfection in Zimbabwe.

    Science.gov (United States)

    Mosler, H-J; Kraemer, S M; Johnston, R B

    2013-01-01

    To use a psychological theory of behavioural change to measure and interpret the effectiveness of different promotional strategies for achieving long-term usage of a household water treatment and safe storage (HWTS) system in peri-urban Zimbabwe. Solar disinfection (SODIS) was introduced into five peri-urban communities near Harare, Zimbabwe. Six different interventions were developed and were applied in four communities in different combinations, with the fifth remaining as a control area where no interventions were implemented. Throughout the 26 months of the study nine longitudinal panel surveys were conducted in which SODIS usage was estimated using three separate metrics: reported, calculated, and observed. A total of 1551 people were interviewed. The three indicators of SODIS usage broadly agreed with one another. By any measure, the most effective intervention was household visits by trained promoters in combination with persuasion. Households which received household visits maintained SODIS usage rates of 65% or more, even six months after the cessation of all promotional activities. Households receiving other interventions were significantly less effective. Interventions like prompts or public commitment after the application of household visits were effective at maintaining good practices once these were established. Household promotion in combination with persuasion appears more effective than other approaches, especially when followed with interventions targeting the maintenance of the new behaviour. With this intervention it is possible that around 65% of the households continue to use solar water disinfection (SODIS) more than two years after the initial promotion, and six months after the end of all interventions. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  5. Solar water disinfection by photocatalytic singlet oxygen production in heterogeneous medium

    Energy Technology Data Exchange (ETDEWEB)

    Villen, Laura; Manjon, Francisco; Garcia-Fresnadillo, David; Orellana, Guillermo [Laboratory of Applied Photochemistry, Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2006-12-01

    Water disinfection in isolated rural areas of less-developed countries poses specific problems since operational expenses must be low, chemicals are not easily deployable and qualification of operators is scarce. Therefore, alternative technologies to the widespread chlorination have been considered for household use. We have evaluated the viability of a photocatalytic process for bacteria inactivation with sunlight, affordable 0.8m{sup 2} compound parabolic collectors (CPC) and an UV-vis absorbing ruthenium (II) tris-chelate complex immobilised (2gm{sup -2}) onto porous silicone as singlet molecular oxygen generator. We have tested the efficiency of two CPC prototypes with different configuration of the photosensitising material, namely, a coaxial- and a fin-type one. Mineral water flowing at 2Lmin{sup -1} and spiked with Escherichia coli or Enterococcus faecalis was subject to the photocatalytic treatment for 5h (a 0.6-0.8MJm{sup -2}L{sup -1} dose of 360-700nm sunlight radiation at 40{sup o}N latitude). Using the fin-type reactor under these conditions, the bacterial survival for 10{sup 4} to 10{sup 2}CFUmL{sup -1} initial concentrations drop to ca. 1% and 0.1% for E. coli and E. faecalis, respectively. The average disinfection rates are similar with both photoreactor designs, regardless the bacteria used (ca. 2x10{sup 4} and 2x10{sup 6}CFUL{sup -1}h{sup -1} for the low and the high initial levels of bacteria, respectively). The novel systems are comparable to or better than solid-supported TiO{sub 2} photocatalysts at inactivating waterborne bacteria. (author)

  6. Enhanced formation of disinfection byproducts in shale gas wastewater-impacted drinking water supplies.

    Science.gov (United States)

    Parker, Kimberly M; Zeng, Teng; Harkness, Jennifer; Vengosh, Avner; Mitch, William A

    2014-10-07

    The disposal and leaks of hydraulic fracturing wastewater (HFW) to the environment pose human health risks. Since HFW is typically characterized by elevated salinity, concerns have been raised whether the high bromide and iodide in HFW may promote the formation of disinfection byproducts (DBPs) and alter their speciation to more toxic brominated and iodinated analogues. This study evaluated the minimum volume percentage of two Marcellus Shale and one Fayetteville Shale HFWs diluted by fresh water collected from the Ohio and Allegheny Rivers that would generate and/or alter the formation and speciation of DBPs following chlorination, chloramination, and ozonation treatments of the blended solutions. During chlorination, dilutions as low as 0.01% HFW altered the speciation toward formation of brominated and iodinated trihalomethanes (THMs) and brominated haloacetonitriles (HANs), and dilutions as low as 0.03% increased the overall formation of both compound classes. The increase in bromide concentration associated with 0.01-0.03% contribution of Marcellus HFW (a range of 70-200 μg/L for HFW with bromide = 600 mg/L) mimics the increased bromide levels observed in western Pennsylvanian surface waters following the Marcellus Shale gas production boom. Chloramination reduced HAN and regulated THM formation; however, iodinated trihalomethane formation was observed at lower pH. For municipal wastewater-impacted river water, the presence of 0.1% HFW increased the formation of N-nitrosodimethylamine (NDMA) during chloramination, particularly for the high iodide (54 ppm) Fayetteville Shale HFW. Finally, ozonation of 0.01-0.03% HFW-impacted river water resulted in significant increases in bromate formation. The results suggest that total elimination of HFW discharge and/or installation of halide-specific removal techniques in centralized brine treatment facilities may be a better strategy to mitigate impacts on downstream drinking water treatment plants than altering

  7. Chlorine disinfection of Pseudomonas aeruginosa, total coliforms, Escherichia coli and Enterococcus faecalis: revisiting reclaimed water regulations.

    Science.gov (United States)

    Coronel-Olivares, Claudia; Reyes-Gómez, Lidia María; Hernández-Muñoz, Aurelio; Martínez-Falcón, Ana Paola; Vázquez-Rodríguez, Gabriela A; Iturbe, Ulises

    2011-01-01

    Pathogenic organisms can be transmitted orally through drinking water or through skin and mucosae by both direct and indirect contact, and their presence in water thus has a negative impact on public health. In wastewater treatment plants (WWTP), water is disinfected to inactivate pathogens. The quantification of several microbial indicators in aquatic systems is required to estimate the biological quality of such systems. So far, coliform bacteria have been used as traditional indicators world-wide. This study has assessed the resistance of total coliforms, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis to three dosages of sodium hypochlorite (NaClO) at two exposure times. The bacteria were isolated from secondary effluents of a WWTP located in Hidalgo, Mexico. The results show that the number of colony-forming units of all studied bacterial types decreased when both the NaClO concentration and exposure times increased. However, they were not eliminated. The inclusion of the species Pseudomonas aeruginosa in regulations for treated wastewater quality as a new indicator is highly recommended due to its importance as an opportunistic pathogen. The detection of this species along with the traditional organisms could be particulary significant for reclaimed water to be used with direct human contact.

  8. Multiple linear regression modeling of disinfection by-products formation in Istanbul drinking water reservoirs.

    Science.gov (United States)

    Uyak, Vedat; Ozdemir, Kadir; Toroz, Ismail

    2007-06-01

    Oxidation of raw water with chlorine results in formation of trihalomethanes (THM) and haloacetic acids (HAA). Factors affecting their concentrations have been found to be organic matter type and concentration, pH, temperature, chlorine dose, contact time and bromide concentration, but the mechanisms of their formation are still under investigation. Within this scope, chlorination experiments have been conducted with water reservoirs from Terkos, Buyukcekmece and Omerli lakes, Istanbul, with different water quality regarding bromide concentration and organic matter content. The factors studied were pH, contact time, chlorine dose, and specific ultraviolet absorbance (SUVA). The determination of disinfection by-products (DBP) was carried out by gas chromatography techniques. Statistical analysis of the results was focused on the development of multiple regression models for predicting the concentrations of total THM and total HAA based on the use of pH, contact time, chlorine dose, and SUVA. The developed models provided satisfactory estimations of the concentrations of the DBP and the model regression coefficients of THM and HAA are 0.88 and 0.61, respectively. Further, the Durbin-Watson values confirm the reliability of the two models. The results indicate that under these experimental conditions which indicate the variations of pH, chlorine dosages, contact time, and SUVA values, the formation of THM and HAA in water can be described by the multiple linear regression technique.

  9. Virus disinfection in water by biogenic silver immobilized in polyvinylidene fluoride membranes

    Energy Technology Data Exchange (ETDEWEB)

    Gusseme, B.D.; Fitts, J.; Hennebel, T.; Christiaens, E.; Saveyn, H.; Verbeken, K.; Boon, N.; Verstraete, W.

    2011-03-01

    The development of innovative water disinfection strategies is of utmost importance to prevent outbreaks of waterborne diseases related to poor treatment of (drinking) water. Recently, the association of silver nanoparticles with the bacterial cell surface of Lactobacillus fermentum (referred to as biogenic silver or bio-Ag{sup 0}) has been reported to exhibit antiviral properties. The microscale bacterial carrier matrix serves as a scaffold for Ag{sup 0} particles, preventing aggregation during encapsulation. In this study, bio-Ag{sup 0} was immobilized in different microporous PVDF membranes using two different pre-treatments of bio-Ag{sup 0} and the immersion-precipitation method. Inactivation of UZ1 bacteriophages using these membranes was successfully demonstrated and was most probably related to the slow release of Ag{sup +} from the membranes. At least a 3.4 log decrease of viruses was achieved by application of a membrane containing 2500 mg bio-Ag{sub powder}{sup 0} m{sup -2} in a submerged plate membrane reactor operated at a flux of 3.1 L m{sup -2} h{sup -1}. Upon startup, the silver concentration in the effluent initially increased to 271 {micro}g L{sup -1} but after filtration of 31 L m{sup -2}, the concentration approached the drinking water limit (= 100 {micro}g L{sup -1}). A virus decline of more than 3 log was achieved at a membrane flux of 75 L m{sup -2} h{sup -1}, showing the potential of this membrane technology for water disinfection on small scale. In biogenic silver, silver nanoparticles are attached to a bacterial carrier matrix. Bio-Ag{sup 0} was successfully immobilized in PVDF membranes using immersion-precipitation. The antiviral activity of this material was demonstrated in a plate membrane reactor. The antimicrobial mechanism was most probably related to the slow release of Ag{sup +} ions. The membranes can be applied for treatment of limited volumes of contaminated water.

  10. The effect of inorganic precursors on disinfection byproduct formation during UV-chlorine/chloramine drinking water treatment.

    Science.gov (United States)

    Lyon, Bonnie A; Dotson, Aaron D; Linden, Karl G; Weinberg, Howard S

    2012-10-01

    Ultraviolet (UV) disinfection is being increasingly used in drinking water treatment. It is important to understand how its application to different types of water may influence finished water quality, particularly as anthropogenic activity continues to impact the quality of source waters. The objective of this study was to evaluate the effect of inorganic precursors on the formation of regulated and unregulated disinfection byproducts (DBPs) during UV irradiation of surface waters when combined with chlorination or chloramination. Samples were collected from three drinking water utilities supplied by source waters with varying organic and inorganic precursor content. The filtered samples were treated in the laboratory with a range of UV doses delivered from low pressure (LP, UV output at 253.7 nm) and medium pressure (MP, polychromatic UV output 200-400 nm) mercury lamps followed by chlorination or chloramination, in the presence and absence of additional bromide and nitrate. The regulated trihalomethanes and haloacetic acids were not affected by UV pretreatment at disinfection doses (40-186 mJ/cm²). With higher doses (1000 mJ/cm²), trihalomethane formation was increased 30-40%. While most effects on DBPs were only observed with doses much higher than typically used for UV disinfection, there were some effects on unregulated DBPs at lower doses. In nitrate-spiked samples (1-10 mg N/L), chloropicrin formation doubled and increased three- to six-fold with 40 mJ/cm² MP UV followed by chloramination and chlorination, respectively. Bromopicrin formation was increased in samples containing bromide (0.5-1 mg/L) and nitrate (1-10 mg N/L) when pretreated with LP or MP UV (30-60% with 40 mJ/cm² LP UV and four- to ten-fold increase with 40 mJ/cm² MP UV, after subsequent chlorination). The formation of cyanogen chloride doubled and increased three-fold with MP UV doses of 186 and 1000 mJ/cm², respectively, when followed by chloramination in nitrate-spiked samples but

  11. The Effect of Different Boiling and Filtering Devices on the Concentration of Disinfection By-Products in Tap Water

    OpenAIRE

    Glòria Carrasco-Turigas; Villanueva, Cristina M.; Fernando Goñi; Panu Rantakokko; Nieuwenhuijsen, Mark J.

    2013-01-01

    Disinfection by-products (DBPs) are ubiquitous contaminants in tap drinking water with the potential to produce adverse health effects. Filtering and boiling tap water can lead to changes in the DBP concentrations and modify the exposure through ingestion. Changes in the concentration of 4 individual trihalomethanes (THM4) (chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)), MX, and bromate were tested when boiling and filtering high bromine-conta...

  12. Drinking water biofilms on copper and stainless steel exhibit specific molecular responses towards different disinfection regimes at waterworks.

    Science.gov (United States)

    Jungfer, Christina; Friedrich, Frank; Varela Villarreal, Jessica; Brändle, Katharina; Gross, Hans-Jürgen; Obst, Ursula; Schwartz, Thomas

    2013-09-01

    Biofilms growing on copper and stainless steel substrata in natural drinking water were investigated. A modular pilot-scale distribution facility was installed at four waterworks using different raw waters and disinfection regimes. Three-month-old biofilms were analysed using molecular biology and microscopy methods. High total cell numbers, low counts of actively respiring cells and low numbers of cultivable bacteria indicated the high abundance of viable but not cultivable bacteria in the biofilms. The expression of the recA SOS responsive gene was detected and underlined the presence of transcriptionally active bacteria within the biofilms. This effect was most evident after UV disinfection, UV oxidation and UV disinfection with increased turbidity at waterworks compared to chemically treated and non-disinfected systems. Furthermore, live/dead staining techniques and environmental scanning electron microscopy imaging revealed the presence of living and intact bacteria in biofilms on copper substrata. Cluster analyses of DGGE profiles demonstrated differences in the composition of biofilms on copper and steel materials.

  13. The effect of boiling water on disinfection by-product exposure.

    Science.gov (United States)

    Krasner, Stuart W; Wright, J Michael

    2005-03-01

    Chloraminated and chlorinated waters containing bromide were used to determine the impact of boiling on disinfection by-product (DBP) concentrations. No significant changes were detected in the concentrations of the dihalogenated haloacetic acids (DXAAs) (i.e., dichloro-, bromochloro-, dibromoacetic acid) upon boiling of chloraminated water, whereas the levels of the trihalogenated haloacetic acids (TXAAs) (i.e., trichloro- (TCAA), bromodichloro- (BDCAA), dibromochloroacetic acid (DBCAA)) decreased over time (e.g., 9-37% for TCAA). Increased DXAA concentrations (58-68%) were detected in the boiled chlorinated sample, which likely resulted from residual chlorine reacting with DXAA precursors. TCAA concentration was unchanged after boiling chlorinated water for 1 min, but a 30% reduction was observed after 5 min of boiling. BDCAA concentrations decreased 57% upon boiling for 1 min and were completely removed after 2 min of boiling, whereas DBCAA was removed after boiling chlorinated water for 1 min. Trihalomethane concentrations were reduced in both chloraminated (74-98%) and chlorinated (64-98%) water upon boiling. Boiling chloraminated water for 1 min reduced chloroform concentration by 75%. Chloroform was reduced by only 34% in chlorinated water after a 1 min boil, which indicates that simultaneous formation and volatilization of chloroform was occurring. Most of the remaining DBPs (e.g. haloketones, chloral hydrate, haloacetonitriles) were removed by at least 90% after 1 min of boiling in both samples. These data suggest that other mechanisms (e.g., hydrolysis) may have been responsible for removal of the non-volatile DBPs and further highlight the importance of examining individual species when estimating thermal effects on DBP concentrations.

  14. Occurrence, profiling and prioritization of halogenated disinfection by-products in drinking water of China.

    Science.gov (United States)

    Ding, Huanhuan; Meng, Liping; Zhang, Haifeng; Yu, Jianwei; An, Wei; Hu, Jianying; Yang, Min

    2013-07-01

    The occurrence of 28 disinfection by-products (DBPs), which were divided into 5 groups, in 70 drinking water treatment plants in 31 cities across China was investigated, and the toxic potency of each DBP group was calculated using mammalian cell toxicity data from previous studies for profiling. Of the 28 DBPs, 21 were detected with an average frequency of detection of 50%. Trihalomethanes (THM4) and haloacetic acids (HAAs) were the most predominant species, whose median concentration levels were at 10.53 and 10.95 μg L(-1), respectively. Two of four iodinated trihalomethanes (I-THMs) were detected, and the concentration of the I-THMs ranged from under the detection limit to 5.58 μg L(-1). The total concentration of haloacetonitriles (HANs) in different water samples ranged from under the limit of detection to 39.20 μg L(-1), with a median concentration of 1.11 μg L(-1). Two of four halonitromethanes (HNMs) were detected, and the maximum concentrations of chloronitromethane (CNM) and trichloronitromethane (TCNM) were 0.96 and 0.28 μg L(-1), respectively. HANs were found to be the most potent DBP group in terms of cytotoxicity, and HANs and HAAs had the same level of genotoxic potency. These results indicate that although at a low concentration level, the toxic potency of the unregulated HANs in drinking water may not be neglected.

  15. The photocatalytic enhancement of acrylic and PET solar water disinfection (SODIS) bottles.

    Science.gov (United States)

    Carey, J M; Perez, T M; Arsiaga, E G; Loetscher, L H; Boyd, J E

    2011-01-01

    The solar water disinfection method (SODIS) was modified by the addition of a photocatalytic layer of titania on the interior surface of polyethylene terephthalate (PET) and acrylic bottles. Titania was solvent deposited on the interior of commercially available PET bottles, as well as bottles that were constructed from acrylic. Uncoated and titania-coated acrylic bottles removed 3,000,000-5,000,000 colony forming units per milliliter of K12 E. coli from 670 mL of contaminated water in 40 min of solar irradiance. After five hours of sunlight exposure, the concentration of 10 ppm methyl orange (a representative organic water contaminant), was reduced by 61% using the titania-coated acrylic bottles. The concentration of 87 ppb microcystin-LR (a representative algal toxin) was reduced by 70% after 7 hours of sunlight exposure in the titania-coated acrylic bottles. Acrylic is an effective alternative to PET for use in the SODIS method due to its greater UV transparency. The addition of titania to PET and acrylic bottles confers the ability to remove chemical contaminants in addition to inactivating microbiological contaminants.

  16. Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

    Science.gov (United States)

    Moletta-Denat, Marina; Frère, Jacques; Onillon, Séverine; Trouilhé, Marie-Cécile; Robine, Enric

    2012-01-01

    Legionella species are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics of Legionella spp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics of Legionella and eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenic Legionella species remained after the heat shock and chemical treatments (Legionella pneumophila and Legionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebae sp., Vannella sp., and Hartmanella vermiformis) and after the first heat shock treatment, but only H. vermiformis remained. However, another protozoan affiliated with Alveolata, which is known as a host cell for Legionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effective Legionella disinfection may be dependent on the elimination of these important microbial components. We suggest that eradicating Legionella in hot water networks requires better study of bacterial and eukaryal species associated with Legionella in biofilms. PMID:22820326

  17. Disinfection byproduct formation in drinking water sources: A case study of Yuqiao reservoir.

    Science.gov (United States)

    Zhai, Hongyan; He, Xizhen; Zhang, Yan; Du, Tingting; Adeleye, Adeyemi S; Li, Yao

    2017-08-01

    This study investigated the potential formation of disinfection byproducts (DBPs) during chlorination and chloramination of 20 water samples collected from different points of Yuqiao reservoir in Tianjin, China. The concentrations of dissolved organic matter and ammonia decreased downstream the reservoir, while the specific UV absorbance (SUVA: the ratio of UV254 to dissolved organic carbon) increased [from 0.67 L/(mg*m) upstream to 3.58 L/(mg*m) downstream]. The raw water quality played an important role in the formation of DBPs. During chlorination, haloacetic acids (HAAs) were the major DBPs formed in most of the water samples, followed by trihalomethanes (THMs). CHCl3 and CHCl2Br were the major THM species, while trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were the major HAA species. Chloramination, on the other hand, generally resulted in lower concentrations of THMs (CHCl3), HAAs (TCAA and DCAA), and haloacetonitriles (HANs). All the species of DBPs formed had positive correlations with the SUVA values, and HANs had the highest one (R(2) = 0.8). The correlation coefficients between the analogous DBP yields and the SUVA values in chlorinated samples were close to those in chloraminated samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Modelling of Non-Linear Pilot Disinfection Water System: A Bond Graph Approach

    Directory of Open Access Journals (Sweden)

    Naoufel ZITOUNI

    2012-08-01

    Full Text Available The ultraviolet (UV irradiations are used to solve the bacteriological problem of the drinking water quality. A discharge-gas lamp is used to produce this type of irradiation. The UV lamp is fed by photovoltaic (PV energy via electronic ballast composed by an inverter, a transformer and resonant circuit (RLC. The aim of this work is to give a useful global model of the system. In particular, we introduce the complicated UV lamp model and the water disinfection kinetics, where the radiant energy flux emitted by the discharge-gas lamp and the arc voltage are a complex functions of the current and time. This system is intended to be mainly used in rural zones, the photovoltaic modules as source of energy is an adequate solution. To optimise the power transfer from the PV array to ballast and UV lamp, a Maximum Power Point Tracking (MPPT device may be located between PV array and the loads. In this paper, we developed a bond-graph model which gives the water quality from UV flow, gas type, pressure, lamp current and geometrical characteristic. Finally reliable simulations are established and compared with experimental tests.

  19. Visible light photocatalytic water disinfection and its kinetics using Ag-doped titania nanoparticles.

    Science.gov (United States)

    Younas, Hassan; Qazi, Ishtiaq A; Hashmi, Imran; Awan, M Ali; Mahmood, Asif; Qayyum, Hafiz Adil

    2014-01-01

    The UN estimated about five million deaths every year due to water-borne diseases, accounting from four billion patients. Keeping in view, the ever increasing health issues and to undermine this statistics, a reliable and sustainable water-treatment method has been developed using visible light for water treatment. titania nanoparticles (NPs) have been synthesized successfully by a more applicable method Viz: liquid impregnation (LI) method. The bacterial death rate by photocatalysis under visible light was studied by employing a typical fluorescent source and was found to follow pseudo first-order reaction kinetics. The nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy to deduce their size range, surface morphology, and elemental compositions, respectively. Among all the prepared grades, 1% Ag-TiO2 was found to be a very effective photocatalytic agent against Escherichia coli. The resulted photoinactivated data were also evaluated by different empirical kinetic models for bacterial inactivation. Hom, Hom-power, Rational, and Selleck models were not able to explain the disinfection kinetics but modified-Hom model fitted best with the experimentally obtained data by producing a shoulder, log-linear, and a tail region.

  20. Development of silver and zinc oxide decorated nanoclay containing polymeric composites for water disinfection applications

    Energy Technology Data Exchange (ETDEWEB)

    Motshekga, Sarah C. [DST/CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, 0001 (South Africa); Ray, Suprakas Sinha [DST/CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Onyango, Maurice S. [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, 0001 (South Africa); Momba, Maggie N. B. [Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Arcadia Campus, 0001 Pretoria (South Africa)

    2015-05-22

    Contaminated drinking water has serious implications to the human health that could lead to death. The rapid growth of bacterial contamination in drinking water is alarming, and yet a robust and cost effective method with less limitation has not been developed. The current study is aimed at evaluating the performance of nanoclay composites dispersed in chitosan biopolymer as an antibacterial material. The performances of the composites were evaluated using the batch kinetic studies. Three composites of Ag-CtsB, ZnO-CtsB and Ag/ZnO-CtsB were prepared and evaluated against gram negative Escherichia coli and gram positive Enterococcus faecalis bacteria. The composites were characterized by powder X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and BET surface area measurements. Antibacterial activity results showed that the composites can be a potent bactericide material for water disinfection as they are highly effective against both gram negative and gram positive bacteria tested. Whereas both Ag-CtsB and ZnO-CtsB composites showed good antibacterial activity against bacteria with removal efficiency from 51%, best antibacterial activity was observed with Ag/ZnO-CtsB composite with removal efficiency from 78%. The results revealed that Ag/ZnO-CtsB composite is a promising bactericide that is highly effective against both gram negative and gram positive bacteria tested.

  1. Chemical disinfection of combined sewer overflow waters using performic acid or peracetic acids

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar; Thornberg, Dines; Berner, Jesper

    2014-01-01

    We investigated the possibility of applying performic acid (PFA) and peracetic acid (PAA) for disinfection of combined sewer overflow (CSO) in existing CSO management infrastructures. The disinfection power of PFA and PAA towards Escherichia coli (E. coli) and Enterococcus was studied in batch......-scale and pre-field experiments. In the batch-scale experiment, 2.5 mg L− 1 PAA removed approximately 4 log unit of E. coli and Enterococcus from CSO with a 360 min contact time. The removal of E. coli and Enterococcus from CSO was always around or above 3 log units using 2–4 mg L− 1 PFA; with a 20 min contact...... time in both batch-scale and pre-field experiments. There was no toxicological effect measured by Vibrio fischeri when CSO was disinfected with PFA; a slight toxic effect was observed on CSO disinfected with PAA. When the design for PFA based disinfection was applied to CSO collected from an authentic...

  2. Exopolymeric substances from drinking water biofilms: Dynamics of production and relation with disinfection by products.

    Science.gov (United States)

    Lemus Pérez, M F; Rodríguez Susa, M

    2017-06-01

    Exopolymeric substances (EPS) as an external matrix of biofilm could react with disinfectants in drinking water networks forming disinfection by-products (DBP). Based on an experimental setup using two chlorine conditions-biofilm 1 (2.6 ± 0.8 mgCl/L) and biofilm 2 (0.7 ± 0.2 mg Cl/L)-samples of biofilms were recovered during 9 campaigns and EPS were extracted. Analyses of SUVA, fluorescence and amino acid (AA) content were carried out on the EPS to observe variation over time and correlations with DBP formation potential (DBPfp) after chlorination. SUVA values were under 2 L/mgC*m showing that both EPS were hydrophilic. Slightly higher SUVA in biofilm 2 with low variation over time was observed. Fluorescence showed that aromatic proteins and fulvic like substances were the principal components and increased in biofilm 1 over time. AA decreased with time, and higher values of alanine, threonine, proline and isoleucine were observed in biofilm 2. Based on general associations, the SUVA of biofilm 2 correlated well with chloroform (CF) (r = 0.80). Generally, in both biofilms, tryptophan-like substances were negatively correlated with DBP while humic acid-like substances correlated positively, but with low indexes (r = 0.3-0.6). Correlations of data from individual sampling increased the indices (r over 0.8), suggesting a temporal influence of other factors on DBPfp such as inorganics, filtered water and the structural composition of EPS. In biofilm 1, Br-haloacetic acids (Br-HAA), dibromoacetonitrile and bromochloro acetonitrile were inversely associated with arginine and valine, as were di and trichloropropanone to arginine. On the contrary, in biofilm 2, the following amino acids correlated positively with DBP: alanine with Br-HAA, alanine with CF, alanine with N-DBP (chloropicrin, di and tri-chloro acetonitrile), and valine with CF. As this is the first report about the relation between temporal variation of EPS and DBPfp of biofilms in two different

  3. Applications of Photocatalytic Disinfection

    Directory of Open Access Journals (Sweden)

    Joanne Gamage

    2010-01-01

    Full Text Available Due to the superior ability of photocatalysis to inactivate a wide range of harmful microorganisms, it is being examined as a viable alternative to traditional disinfection methods such as chlorination, which can produce harmful byproducts. Photocatalysis is a versatile and effective process that can be adapted for use in many applications for disinfection in both air and water matrices. Additionally, photocatalytic surfaces are being developed and tested for use in the context of “self-disinfecting” materials. Studies on the photocatalytic technique for disinfection demonstrate this process to have potential for widespread applications in indoor air and environmental health, biological, and medical applications, laboratory and hospital applications, pharmaceutical and food industry, plant protection applications, wastewater and effluents treatment, and drinking water disinfection. Studies on photocatalytic disinfection using a variety of techniques and test organisms are reviewed, with an emphasis on the end-use application of developed technologies and methods.

  4. Improved Drinking Water Disinfection with UVC-LEDs for Escherichia Coli and Bacillus Subtilis Utilizing Quartz Tubes as Light Guide

    Directory of Open Access Journals (Sweden)

    Andrej Gross

    2015-08-01

    Full Text Available A new approach is investigated utilizing light guidance capabilities of optical pure quartz glass in order to maximize drinking water disinfection efficiency with UVC-light-emitting diodes (LEDs. Two experimental setups consisting of soda-lime AR® glass (VWR, Darmstadt, Germany or HSQ® 100 quartz glass (Heraeus, Wasserburg, Germany reactors were designed to compare disinfection rates with and without total reflection of UVC radiation along the reactor walls. Each reactor was filled with 9 mL bacteria samples containing either E. coli DSM (Deutsche Sammlung von Mikroorganismen 498 or B. subtilis DSM 402 strains (concentration 1–3 × 106 colony forming units (CFU/mL with and without additional mixing and irradiation periods of 10, 40, and 90 s. Disinfection rates were increased up to 0.95 log10 (E. coli and 0.75 log10 (B. subtilis by the light guide approach in stagnant samples. The same experiments with mixing of the samples resulted in an increased disinfection efficiency of 3.07 log10 (E. coli and 1.59 log10 (B. subtilis. Optical calculations determine that total reflection is achieved with the applied UVC-LED’s viewing angle of 15°. Furthermore measurements show that HSQ® 100 quartz has a transmittance of 92% at 280 nm UVC irradiation compared to the transmittance of soda-lime glass of 2% (1 mm wall thickness.

  5. Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

    Science.gov (United States)

    Birmele, Michele N.; McCoy, LaShelle e.; Roberts, Michael S.

    2011-01-01

    Microbial growth is common on wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and physical disinfection methods. Advanced control technologies are needed to limit microorganisms and increase the reliability of life support systems required for long-duration human missions. Silver ions and compounds are widely used as antimicrobial agents for medical applications and continue to be used as a residual biocide in some spacecraft water systems. The National Aeronautics and Space Administration (NASA) has identified silver fluoride for use in the potable water system on the next generation spacecraft. Due to ionic interactions between silver fluoride in solution and wetted metallic surfaces, ionic silver is rapidly depleted from solution and loses its antimicrobial efficacy over time. This report describes research to prolong the antimicrobial efficacy of ionic silver by maintaining its solubility. Three types of metal coupons (lnconel 718, Stainless Steel 316, and Titanium 6AI-4V) used in spacecraft potable water systems were exposed to either a continuous flow of water amended with 0.4 mg/L ionic silver fluoride or to a static, pre-treatment passivation in 50 mg/L ionic silver fluoride with or without a surface oxidation pre-treatment. Coupons were then challenged in a high-shear, CDC bioreactor (BioSurface Technologies) by exposure to six bacteria previously isolated from spacecraft potable water systems. Continuous exposure to 0.4 mg/L ionic silver over the course of 24 hours during the flow phase resulted in a >7-log reduction. The residual effect of a 24-hour passivation treatment in 50 mg/L of ionic silver resulted in a >3-log reduction, whereas a two-week treatment resulted in a >4-log reduction. Results indicate that 0.4 mg/L ionic silver is an effective biocide against many bacteria and that a prepassivation of metal surfaces with silver can provide additional microbial control.

  6. Desalinated and blended water in Saudi Arabia: human exposure and risk analysis from disinfection byproducts

    Directory of Open Access Journals (Sweden)

    Chowdhury Imran Rahman

    2017-01-01

    Full Text Available Saudi Arabia produces the largest amount of desalinated water as a single country. The desalinated water is typically blended with treated groundwater, pH adjusted and chlorinated prior to supply to the communities. The desalinated seawater and/or blended water contains various types of disinfection byproducts (DBPs, some of which may induce cancer risks to human through lifetime exposure. In this study, occurrences of trihalomethanes (THMs in desalinated and blended water in Saudi Arabia were investigated and their exposure and risks were predicted. The chronic daily intakes of CHCl3, BDCM, DBCM and CHBr3 were estimated to be 8.38×10−5, 7.57×10−5, 2.54×10−5 and 4.32×10−4 mg/kg-day respectively. The overall cancer risk was 1.78×10−5 with the range of 7.40×10−7 – 9.26×10−5 and the average hazard index was 3.49×10−2 with the range of 1.20×10−3 – 2.34×10−1. The loss of disability adjusted life years (DALY were estimated to be 25.1 per year and the average cancer risk had 8.48×10−7 DALY per person per year. The financial burden was estimated to be US$2.72 million with the range of US$2.52–2.91 million. The findings may assist in better understanding and reducing cancer risks from DBPs in desalinated and blended water.

  7. Dielectric Barrier Discharge based Mercury-free plasma UV-lamp for efficient water disinfection.

    Science.gov (United States)

    Prakash, Ram; Hossain, Afaque M; Pal, U N; Kumar, N; Khairnar, K; Mohan, M Krishna

    2017-12-12

    A structurally simple dielectric barrier discharge based mercury-free plasma UV-light source has been developed for efficient water disinfection. The source comprises of a dielectric barrier discharge arrangement between two co-axial quartz tubes with an optimized gas gap. The outer electrode is an aluminium baked foil tape arranged in a helical form with optimized pitch, while the inner electrode is a hollow aluminium metallic rod, hermetically sealed. Strong bands peaking at wavelengths 172 nm and 253 nm, along with a weak band peaking at wavelength 265 nm have been simultaneously observed due to plasma radiation from the admixture of xenon and iodine gases. The developed UV source has been used for bacterial deactivation studies using an experimental setup that is an equivalent of the conventional house-hold water purifier system. Deactivation studies for five types of bacteria, i.e., E. coli, Shigella boydii, Vibrio, Coliforms and Fecal coliform have been demonstrated with 4 log reductions in less than ten seconds.

  8. Removing of Disinfection By-Product Precursors from Surface Water by Using Magnetic Graphene Oxide.

    Directory of Open Access Journals (Sweden)

    Zhongmou Liu

    Full Text Available The magnetic graphene oxide (MGO was successfully synthesised by the in situ chemical co-precipitation method with Fe3+, Fe2+ and graphene oxide (GO in laboratory and, was used as an adsorbent for disinfection by-product (DBP precursors removing from four natural surface water samples. The results indicate that various DBPs formation significantly decreased by 7-19% to 78-98% for the four samples after MGO treatment and, the treatment process was rapidly reached equilibrium within 20 minutes. The DBP precursors removal efficiency decreased with the increasing pH value from 4 to 10. Hydrophobic compounds (humic acid and fulvic acid are more sensitive to MGO, whereas hydrophilic and nitrogenous compounds (aromatic proteins are more insensitive. MGO could be regenerated by using 20% (v/v ethanol and, the DBP precursors removal efficiency can stay stable after five cycles. These results indicate that MGO can be utilized as a promising adsorbent for the removal of DBP precursors from natural surface water.

  9. Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water.

    Science.gov (United States)

    McGuigan, K G; Méndez-Hermida, F; Castro-Hermida, J A; Ares-Mazás, E; Kehoe, S C; Boyle, M; Sichel, C; Fernández-Ibáñez, P; Meyer, B P; Ramalingham, S; Meyer, E A

    2006-08-01

    To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water. Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m(-2) for different exposure times at a constant temperature of 40 degrees C. Infectivity tests were carried out using CD-1 suckling mice in the Cryptosporidium experiments and newly weaned CD-1 mice in the Giardia experiments. Exposure times of > or =10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4',6-diamidino-2-phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall. Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia. These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man-made disasters against not only bacterial but also protozoan pathogens.

  10. Efficacy of the solar water disinfection method in turbid waters experimentally contaminated with Cryptosporidium parvum oocysts under real field conditions.

    Science.gov (United States)

    Gómez-Couso, H; Fontán-Saínz, M; Sichel, C; Fernández-Ibáñez, P; Ares-Mazás, E

    2009-06-01

    To investigate the efficacy of the solar water disinfection (SODIS) method for inactivating Cryptosporidium parvum oocysts in turbid waters using 1.5 l polyethylene terephthalate (PET) bottles under natural sunlight. All experiments were performed at the Plataforma Solar de Almería, located in the Tabernas Desert (Southern Spain) in July and October 2007. Turbid water samples [5, 100 and 300 nephelometric turbidity units (NTU)] were prepared by addition of red soil to distilled water, and then spiked with purified C. parvum oocysts. PET bottles containing the contaminated turbid waters were exposed to full sunlight for 4, 8 and 12 h. The samples were then concentrated by filtration and the oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. Results After an exposure time of 12 h (cumulative global dose of 28.28 MJ/m(2); cumulative UV dose of 1037.06 kJ/m(2)) the oocyst viabilities were 11.54%, 25.96%, 41.50% and 52.80% for turbidity levels of 0, 5, 100 and 300 NTU, respectively, being significantly lower than the viability of the initial isolate (P < 0.01). SODIS method significantly reduced the potential viability of C. parvum oocysts on increasing the percentage of oocysts that took up the dye PI (indicator of cell wall integrity), although longer exposure periods appear to be required than those established for the bacterial pathogens usually tested in SODIS assays. SODIS.

  11. Comparison of UV-LED and low pressure UV for water disinfection: Photoreactivation and dark repair of Escherichia coli.

    Science.gov (United States)

    Li, Guo-Qiang; Wang, Wen-Long; Huo, Zheng-Yang; Lu, Yun; Hu, Hong-Ying

    2017-12-01

    Studies on ultraviolet light-emitting diode (UV-LED) water disinfection have shown advantages, such as safety, flexible design, and lower starting voltages. However, information about reactivation after UV-LED disinfection is limited, which is an important issue of UV light-based technology. In this study, the photoreactivation and dark repair of Escherichia coli after UV-LEDs and low pressure (LP) UV disinfection were compared. Four UV-LED units, 265 nm, 280 nm, the combination of 265 + 280 (50%), and 265 + 280 (75%) were tested. 265 nm LEDs was more effective than 280 nm LEDs and LP UV lamps for E. coli inactivation. No synergic effect for disinfection was observed from the combination of 265 and 280 nm LEDs. 265 nm LEDs had no different reactivation performances with that of LP UV, while 280 nm LEDs could significantly repress photoreactivation and dark repair at a low irradiation intensity of 6.9 mJ/cm2. Furthermore, the UV-induced damage of 280 nm LEDs was less repaired which was determined by endonuclease sensitive site (ESS) assay. The impaired protein activities by 280 nm LEDs might be one of the reasons that inhibited reactivation. A new reactivation rate constant, Kmax, was introduced into the logistic model to simulate the reactivation data, which showed positive relationship with the maximum survival ratio and was more reasonable to interpret the results of photoreactivation and dark repair. This study revealed the distinct roles of different UV lights in disinfection and reactivation, which is helpful for the future design of UV-LED equipment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Solar disinfection improves drinking water quality to prevent diarrhea in under-five children in Sikkim, India

    Directory of Open Access Journals (Sweden)

    B B Rai

    2010-01-01

    Full Text Available Background: Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children. Aims and Objectives: To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method. Materials and Methods: This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1 st May 2007 to 30 th November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance. Results: After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant. Conclusions: In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in

  13. Photodynamic inactivation of microbial pathogens: disinfection of water and prevention of water-borne diseases.

    Science.gov (United States)

    Jori, Giulio; Magaraggia, Michela; Fabris, Clara; Soncin, Marina; Camerin, Monica; Tallandini, Laura; Coppellotti, Olimpia; Guidolin, Laura

    2011-01-01

    Porphyrins have been shown to act as very efficient photosensitizing agents against a broad number of microbial pathogens, including bacteria, fungi, and protozoa. This property has promising applications at a clinical level for the treatment of infectious diseases by photodynamic therapy. Moreover, this technique is also being used to address environmental problems of high significance, such as the decontamination of wastewaters, the disinfection of fish-farming tanks, the protection of animal species (e.g., amphibians and reptiles) that are endangered by pathogens whose life cycle takes place largely in aqueous media, and the control of populations of noxious insects. Such diversified applications take advantage of the availability of a truly large number of porphyrin derivatives with chemical structures that can be tailored to comply with the physical and chemical properties as well as the biological features of several milieus. In addition, the property typical of porphyrins to absorb essentially all of the wavelengths in the sun emission spectrum allows the promotion of processes largely based on natural resources with significant energy savings and low impact on ecosystems.

  14. Retrospective analysis of endodontic casuistics related to the chemo-mechanical root canal desinfection

    OpenAIRE

    Wenk, Katja

    2016-01-01

    Objectives: The aim of the present study was to investigate and compare the clinical outcomes of two different standardized endodontic irrigation protocols. It was assumed that the additional use of ethylenediaminetetraacetate (EDTA) as irrigation fluid and passive ultrasonic irrigation (PUI) would result in an increased rate of treatment success compared to the irrigation only using sodium hypochlorite (NaOCl) during the chemical root canal disinfection. Materials and methods: Data and ra...

  15. APPLICATION OF OZONATION IN DRINKING WATER DISINFECTION BASED ON AN ENVIRONMENTAL MANAGEMENT STRATEGY APPROACH USING SWOT METHOD

    Directory of Open Access Journals (Sweden)

    G. R. Nabi Bidhendi, H. Hoveidi, H. R. Jafari, A. R. Karbassi, T. Nasrabadi

    2006-01-01

    Full Text Available The disinfecting process has been considered as one of the most important steps in drinking water treatment and improper attention to this process can caused a social disaster. Until now, different methods have been used for drinking water disinfection, such as using the ultra-violet light and adding ozone or chloride. Because of the water sources contaminations, especially in surface water which is in closer contact with different pollutants, adding chloride to water, generally applied all over the world, can cause some adverse impacts on the residential users such as the ones caused by chlorinated chemicals and Trihalomethanes as the secondary products. Regarding to high level of electrical energy consumption and considering resulted costs, this method have not been developed in Iran. This study aimed to explain the drinking water ozonation process opportunities and threats. Usage of ozone is a useful and effective method and could be resulted in high oxidizing property, not producing carcinogens and eliminating bacteria, viruses and other disease-causing elements. On the other hand mentioned method will process in shorter time in comparison with other water treatment methods. There are different techniques for the strategic management as a suitable tool to conduct related environmental management plan. The study management methodology is based on SWOT; so it describes the management functional strategies for ozonation as a suitable drinking water treatment method. Finally, using the QSPM matrix, the hierarchical priority of these strategies was defined. It seems quite important that for the implementation of this process, the foreign experiments in disinfecting drinking water be studied and some proper workforce be trained.

  16. Disinfection potential of ozone, ultraviolet-C and their combination in wash water for the fresh-cut vegetable industry.

    Science.gov (United States)

    Selma, María V; Allende, Ana; López-Gálvez, Francisco; Conesa, María A; Gil, María I

    2008-09-01

    The purpose of this research was to investigate the disinfection efficacy of ozone (O(3)) and UV-C illumination (UV), and their combination (O(3)-UV) for reducing microbial flora of fresh-cut onion, escarole, carrot, and spinach wash waters collected from the industry. Furthermore, the influence of water physicochemical parameters on the decontamination efficacy and the effect of these technologies on physicochemical quality of wash water were analyzed. O(3), UV, and O(3)-UV were effective disinfection treatments on vegetable wash water, with a maximum microbial reduction of 6.6 log CFU mL(-1) after 60 min treatment with O(3)-UV. However, maximum total microbial reductions achieved by UV and O(3) treatments after 60 min were 4.0 and 5.9 log CFU mL(-1), lower than by O(3)-UV treatment. Furthermore, turbidity of wash water was reduced significantly by O(3) and O(3)-UV treatments, while UV treatment did not affect the physicochemical quality of the water. Conclusions derived from this study illustrate that O(3) and O(3)-UV are alternatives to other sanitizers used in the fresh-cut washing processes. The use of these technologies would allow less frequent changing of spent water and the use of much lower sanitizer doses. Nevertheless, in specific applications such as carrot wash water, where levels of undesirable microbial and chemical constituents are lower than other vegetable wash water, UV treatment could be an appropriate treatment considering cost-effectiveness criteria.

  17. Disinfection byproduct formation during biofiltration cycle: Implications for drinking water production.

    Science.gov (United States)

    Delatolla, R; Séguin, C; Springthorpe, S; Gorman, E; Campbell, A; Douglas, I

    2015-10-01

    The goal of this study was to investigate the potential of biofiltration to reduce the formation potential of disinfection byproducts (DBPs). Particularly, the work investigates the effect of the duration of the filter cycle on the formation potential of total trihalomethanes (TTHM) and five species of haloacetic acids (HAA5), dissolved oxygen (DO), organic carbon, nitrogen and total phosphorous concentrations along with biofilm coverage of the filter media and biomass viability of the attached cells. The study was conducted on a full-scale biologically active filter, with anthracite and sand media, at the Britannia water treatment plant (WTP), located in Ottawa, Ontario, Canada. The formation potential of both TTHMs and HAA5s decreased due to biofiltration. However the lowest formation potentials for both groups of DBPs and or their precursors were observed immediately following a backwash event. Hence, the highest percent removal of DBPs was observed during the early stages of the biofiltration cycle, which suggests that a higher frequency of backwashing will reduce the formation of DBPs. Variable pressure scanning electron microscopy (VPSEM) analysis shows that biofilm coverage of anthracite and sand media increases as the filtration cycle progressed, while biomass viability analysis demonstrates that the percentage of cells attached to the anthracite and sand media also increases as the filtration cycle progresses. These results suggest that the development and growth of biofilm on the filters increases the DPB formation potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Effects of halobenzoquinone and haloacetic acid water disinfection byproducts on human neural stem cells.

    Science.gov (United States)

    Fu, Katherine Z; Li, Jinhua; Vemula, Sai; Moe, Birget; Li, Xing-Fang

    2017-08-01

    Human neural stem cells (hNSCs) are a useful tool to assess the developmental effects of various environmental contaminants; however, the application of hNSCs to evaluate water disinfection byproducts (DBPs) is scarce. Comprehensive toxicological results are essential to the prioritization of DBPs for further testing and regulation. Therefore, this study examines the effects of DBPs on the proliferation and differentiation of hNSCs. Prior to DBP treatment, characteristic protein markers of hNSCs from passages 3 to 6 were carefully examined and it was determined that hNSCs passaged 3 or 4 times maintained stem cell characteristics and can be used for DBP analysis. Two regulated DBPs, monobromoacetic acid (BAA) and monochloroacetic acid (CAA), and two emerging DBPs, 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ) and 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), were chosen for hNSC treatment. Both 2,6-DBBQ and 2,6-DCBQ induced cell cycle arrest at S-phase at concentrations up to 1μmol/L. Comparatively, BAA and CAA at 0.5μmol/L affected neural differentiation. These results suggest DBP-dependent effects on hNSC proliferation and differentiation. The DBP-induced cell cycle arrest and inhibition of normal hNSC differentiation demonstrate the need to assess the developmental neurotoxicity of DBPs. Copyright © 2017. Published by Elsevier B.V.

  19. Antimicrobial materials for water disinfection based on visible-light photocatalysts

    Science.gov (United States)

    Wu, Pinggui

    Since the discovery of photocatalytic water-splitting on TiO2 in 1972, enormous effort has been devoted to the study of TiO2. Since the optical properties of TiO2 and e--h + recombination are essential to the photon-driven applications, these two areas have drawn tremendous research attention in the past few years. But there is no single optimal system to date that has visible-light activity, high photo-efficiency and easy recovery. In this study, chemical co-doping approach was adopted to achieve desirable properties of TiO2-based photocatalyst. Nitrogen and metal ions selected from the transition metal or the rare earth element group were incorporated into TiO2 to induce a red-shift to the visible-light absorption regime and to enhance photocatalytic activity. The anion and cation co-doped TiO2 was made into various forms, including thin film, fiber, and foam that circumvent the problems associated with catalyst recovery. Chemical composition, structure, microstructure, optical, and photocatalytic properties were investigated to characterize each type of the materials. Electronic structure calculation and electron paramagnetic resonance spectroscopy were conducted to understand the role of nitrogen and metal ions. The photocatalytic property of these visible-light-active photocatalysts were studied in the inactivation of bacteria and bacterial spores in water. Fast killing rate was obtained for the inactivation of E. coli, P. aeruginosa, S. aureus and B. subtilis endospores. The results of mechanistic study provided evidence of oxidative damages, and indicated that hydroxyl radicals are one of the key killing species. Atomic force microscopy and electron microscopy showed that the cell walls were attacked by photocatalytic inactivation. The potential application of the photocatalyst in water disinfection was demonstrated by flow-through tests.

  20. Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region

    Energy Technology Data Exchange (ETDEWEB)

    Ndounla, J., E-mail: juliette.ndounla@epfl.ch [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering GPAO, Station 6, CH 1015 Lausanne (Switzerland); Institut International d' Ingénierie de l' Eau et de l' Environnement, Laboratoire Eau, Dépollution, Ecosystème et Santé (LEDES), 01 BP 594 Ouagadougou 01 (Burkina Faso); Pulgarin, C., E-mail: Cesar.pulgarin@epfl.ch [Ecole Polytechnique Fédérale de Lausanne, Institute of Chemical Sciences and Engineering GPAO, Station 6, CH 1015 Lausanne (Switzerland)

    2014-09-15

    The photo-disinfection of water from two different wells (W1, pH: 4.6–5.1 ± 0.02) and (W2 pH: 5.6–5.7 ± 0.02) was carried out during the rainy season at Ouagadougou–Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24 h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO{sub 3}{sup −} concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO{sub 3}{sup −} concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and

  1. La desinfección-antisepsia y esterilización en la atención primaria de salud: Laboratorios Desinfection-antisepsis and sterilization in primay health care: Laboratories

    National Research Council Canada - National Science Library

    Abilio Ubaldo Rodríguez Pérez

    2006-01-01

    ... una política en este sentido.Desinfection-antisepsis and sterilization are procedures that are used as elements to break up the microorganisms transmission chain, preventing possible contaminations in the laboratories at the...

  2. Health gains from solar water disinfection (SODIS): evaluation of a water quality intervention in Yaoundé, Cameroon.

    Science.gov (United States)

    Graf, Jürg; Zebaze Togouet, Serge; Kemka, Norbert; Niyitegeka, Domitille; Meierhofer, Regula; Gangoue Pieboji, Joseph

    2010-12-01

    In developing countries, the burden of diarrhoea is still enormous. One way to reduce transmission of pathogens is by water quality interventions. Solar water disinfection (SODIS) is a low-cost and simple method to improve drinking water quality on household level. This paper evaluates the implementation of SODIS in slum areas of Yaoundé, Cameroon. Promoters trained 2,911 households in the use of SODIS. Two surveys with randomly selected households were conducted before (N=2,193) and after (N=783) the intervention. Using a questionnaire, interviewers collected information on the health status of children under five, on liquid consumption, hygiene and other issues. Prior to the intervention, diarrhoea prevalence amounted to 34.3% among children. After the intervention, it remained stable in the control group (31.8%) but dropped to 22.8% in the intervention group. Households fully complying with the intervention exhibited even less diarrhoea prevalence (18.3%) and diarrhoea risk could be reduced by 42.5%. Multivariate analyses revealed that the intervention effects are also observed when other diarrhoea risk factors, such as hygiene and cleanliness of household surroundings, are considered. According to the data, adoption of the method was associated with marital status. Findings suggest health benefits from SODIS use. Further promotional activities in low-income settings are recommended.

  3. Secondary formation of disinfection by-products by UV treatment of swimming pool water

    Energy Technology Data Exchange (ETDEWEB)

    Spiliotopoulou, Aikaterini [Water ApS, Farum Gydevej 64, 3520 Farum (Denmark); Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark); Hansen, Kamilla M.S., E-mail: kmsh@env.dtu.dk [Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark); Andersen, Henrik R. [Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 113, 2800 Kongens Lyngby (Denmark)

    2015-07-01

    Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination. Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment. The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination. Additionally, no significant

  4. Disinfection of drinking water contaminated with Cryptosporidium parvum oocysts under natural sunlight and using the photocatalyst TiO2.

    Science.gov (United States)

    Méndez-Hermida, Fernando; Ares-Mazás, Elvira; McGuigan, Kevin G; Boyle, Maria; Sichel, Cosima; Fernández-Ibáñez, Pilar

    2007-09-25

    The results of a batch-process solar disinfection (SODIS) and solar photocatalytic disinfection (SPCDIS) on drinking water contaminated with Cryptosporidium are reported. Cryptosporidium parvum oocyst suspensions were exposed to natural sunlight in Southern Spain and the oocyst viability was evaluated using two vital dyes [4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI)]. SODIS exposures (strong sunlight) of 8 and 12h reduced oocyst viability from 98% (+/-1.3%) to 11.7% (+/-0.9%) and 0.3% (+/-0.33%), respectively. SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder (SPCDIS) were found to be more effective than those which were not. After 8 and 16 h of overcast and cloudy solar irradiance conditions, SPCDIS reduced oocyst viability from 98.3% (+/-0.3%) to 37.7% (+/-2.6%) and 11.7% (+/-0.7%), respectively, versus to that achieved using SODIS of 81.3% (+/-1.6%) and 36.0% (+/-1.0%), respectively. These results confirm that solar disinfection of drinking water can be an effective household intervention against Cryptosporidium contamination.

  5. Assessing regulatory violations of disinfection by-products in water distribution networks using a non-compliance potential index.

    Science.gov (United States)

    Islam, Nilufar; Sadiq, Rehan; Rodriguez, Manuel J; Legay, Christelle

    2016-05-01

    Inactivating pathogens is essential to eradicate waterborne diseases. However, disinfection forms undesirable disinfection by-products (DBPs) in the presence of natural organic matter. Many regulations and guidelines exist to limit DBP exposure for eliminating possible health impacts such as bladder cancer, reproductive effects, and child development effects. In this paper, an index named non-compliance potential (NCP) index is proposed to evaluate regulatory violations by DBPs. The index can serve to evaluate water quality in distribution networks using the Bayesian Belief Network (BBN). BBN is a graphical model to represent contributing variables and their probabilistic relationships. Total trihalomethanes (TTHM), haloacetic acids (HAA5), and free residual chlorine (FRC) are selected as the variables to predict the NCP index. A methodology has been proposed to implement the index using either monitored data, empirical model results (e.g., multiple linear regression), and disinfectant kinetics through EPANET simulations. The index's usefulness is demonstrated through two case studies on municipal distribution systems using both full-scale monitoring and modeled data. The proposed approach can be implemented for data-sparse conditions, making it especially useful for smaller municipal drinking water systems.

  6. Gas Chromatography Analyses for Trihalomethanes: An Experiment Illustrating Important Sources of Disinfection By-Products in Water Treatment

    Science.gov (United States)

    Olson, Terese M.; Gonzalez, Alicia C.; Vasquez, Victor R.

    2001-09-01

    Chlorination processes are an important disinfection strategy in drinking water treatment. Side-reactions of chlorine species with naturally present organic matter, however, are known to produce toxic disinfection by-products (DBPs). One important class of DBPs is trihalomethanes. This experiment demonstrates how trihalomethanes form in a chlorination process by using a model substrate, resorcinol, to mimic the reactive moieties present in natural organic matter. To further simulate how bromo-substituted trihalomethanes are typically obtained in a chlorination process, bromide is also added to the resorcinol solution. Reaction pathways and yields for the formation of trihalomethanes are discussed. The experiment provides a meaningful example of gas chromatography analyses of mixtures of environmentally relevant compounds and is suitable for an undergraduate junior/senior level or graduate environmental chemistry course.

  7. Water and Wastewater Disinfection with Peracetic Acid and UV Radiation and Using Advanced Oxidative Process PAA/UV

    Directory of Open Access Journals (Sweden)

    Jeanette Beber de Souza

    2015-01-01

    Full Text Available The individual methods of disinfection peracetic acid (PAA and UV radiation and combined process PAA/UV in water (synthetic and sanitary wastewater were employed to verify the individual and combined action of these advanced oxidative processes on the effectiveness of inactivation of microorganisms indicators of fecal contamination E. coli, total coliforms (in the case of sanitary wastewater, and coliphages (such as virus indicators. Under the experimental conditions investigated, doses of 2, 3, and 4 mg/L of PAA and contact time of 10 minutes and 60 and 90 s exposure to UV radiation, the results indicated that the combined method PAA/UV provided superior efficacy when compared to individual methods of disinfection.

  8. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection

    Science.gov (United States)

    Barber, Larry B.; Hladik, Michelle; Vajda, Alan M.; Fitzgerald, Kevin C.; Douville, Chris

    2015-01-01

    The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m3 d−1 design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration = 2.7 μg L−1; n=5) and 10 HDBPs (mean total concentration = 4.5 μg L−1), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration = 1.4 μg L−1) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had greater relative

  9. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection.

    Science.gov (United States)

    Barber, Larry B; Hladik, Michelle L; Vajda, Alan M; Fitzgerald, Kevin C; Douville, Chris

    2015-10-01

    The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m(3) d(-1) design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration=2.7 μg L(-1); n=5) and 10 HDBPs (mean total concentration=4.5 μg L(-1)), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration=1.4 μg L(-1)) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had greater relative proportions of

  10. Application of ultrasound and quartz sand for the removal of disinfection byproducts from drinking water.

    Science.gov (United States)

    Yang, Wu; Dong, Lili; Luo, Zhen; Cui, Xiaochun; Liu, Jiancong; Liu, Zhongmou; Huo, Mingxin

    2014-04-01

    To the best of our knowledge, little information is available on the combined use of ultrasound (US) and quartz sand (QS) in the removal of disinfection byproducts (DBPs) from drinking water. This study investigates the removal efficiency for 12 DBPs from drinking water by 20 kHz sonolytic treatment, QS adsorption, and their combination. Results indicate that DBPs with logKow≤1.12 could not be sonolysized; for logKow≥1.97, more than 20% removal efficiency was observed, but the removal efficiency was unrelated to logKow. DBPs containing a nitro group are more sensitive to US than those that comprise nitrile, hydrogen, and hydroxyl groups. Among the 12 investigated DBPs, 9 could be adsorbed by QS adsorption. The adsorption efficiency ranged from 12% for 1,1-dichloro-2-propanone to 80% for trichloroacetonitrile. A synergistic effect was found between the US and QS on DBPs removal, and all the 12 DBPs could be effectively removed by the combined use of US and QS. In the presence of US, part of the QS particles were corroded into small particles which play a role in increasing the number of cavitation bubbles and reducing cavitation bubble size and then improve the removal efficiency of DBPs. On the other hand, the presence of US enhances the DBP mass transfer rate to cavitation bubbles and quartz sand. In addition, sonolytic treatment led to a slight decrease of pH, and TOC values decreased under all the three treatment processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Sourav Das

    2017-07-01

    Full Text Available Water borne pathogens present a threat to human health and their disinfection from water poses a challenge, prompting the search for newer methods and newer materials. Disinfection of the Gram-negative bacterium Escherichia coli and the Gram-positive coccal bacterium Staphylococcus aureus in an aqueous matrix was achieved within 60 and 90 min, respectively, at 35 °C using solar-photocatalysis mediated by sonochemically synthesized Ag@ZnO core-shell nanoparticles. The efficiency of the process increased with the increase in temperature and at 55 °C the disinfection for the two bacteria could be achieved in 45 and 60 min, respectively. A new ultrasound-assisted chemical precipitation technique was used for the synthesis of Ag@ZnO core-shell nanoparticles. The characteristics of the synthesized material were established using physical techniques. The material remained stable even at 400 °C. Disinfection efficiency of the Ag@ZnO core-shell nanoparticles was confirmed in the case of real world samples of pond, river, municipal tap water and was found to be better than that of pure ZnO and TiO2 (Degussa P25. When the nanoparticle- based catalyst was recycled and reused for subsequent disinfection experiments, its efficiency did not change remarkably, even after three cycles. The sonochemically synthesized Ag@ZnO core-shell nanoparticles thus have a good potential for application in solar photocatalytic disinfection of water borne pathogens.

  12. Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles.

    Science.gov (United States)

    Das, Sourav; Ranjana, Neha; Misra, Ananyo Jyoti; Suar, Mrutyunjay; Mishra, Amrita; Tamhankar, Ashok J; Lundborg, Cecilia Stålsby; Tripathy, Suraj K

    2017-07-10

    Water borne pathogens present a threat to human health and their disinfection from water poses a challenge, prompting the search for newer methods and newer materials. Disinfection of the Gram-negative bacterium Escherichia coli and the Gram-positive coccal bacterium Staphylococcus aureus in an aqueous matrix was achieved within 60 and 90 min, respectively, at 35 °C using solar-photocatalysis mediated by sonochemically synthesized Ag@ZnO core-shell nanoparticles. The efficiency of the process increased with the increase in temperature and at 55 °C the disinfection for the two bacteria could be achieved in 45 and 60 min, respectively. A new ultrasound-assisted chemical precipitation technique was used for the synthesis of Ag@ZnO core-shell nanoparticles. The characteristics of the synthesized material were established using physical techniques. The material remained stable even at 400 °C. Disinfection efficiency of the Ag@ZnO core-shell nanoparticles was confirmed in the case of real world samples of pond, river, municipal tap water and was found to be better than that of pure ZnO and TiO₂ (Degussa P25). When the nanoparticle- based catalyst was recycled and reused for subsequent disinfection experiments, its efficiency did not change remarkably, even after three cycles. The sonochemically synthesized Ag@ZnO core-shell nanoparticles thus have a good potential for application in solar photocatalytic disinfection of water borne pathogens.

  13. Factors associated with compliance among users of solar water disinfection in rural Bolivia.

    Science.gov (United States)

    Christen, Andri; Duran Pacheco, Gonzalo; Hattendorf, Jan; Arnold, Benjamin F; Cevallos, Myriam; Indergand, Stefan; Colford, John M; Mäusezahl, Daniel

    2011-04-04

    Diarrhoea is the second leading cause of childhood mortality, with an estimated 1.3 million deaths per year. Promotion of Solar Water Disinfection (SODIS) has been suggested as a strategy for reducing the global burden of diarrhoea by improving the microbiological quality of drinking water. Despite increasing support for the large-scale dissemination of SODIS, there are few reports describing the effectiveness of its implementation. It is, therefore, important to identify and understand the mechanisms that lead to adoption and regular use of SODIS. We investigated the behaviours associated with SODIS adoption among households assigned to receive SODIS promotion during a cluster-randomized trial in rural Bolivia. Distinct groups of SODIS-users were identified on the basis of six compliance indicators using principal components and cluster analysis. The probability of adopting SODIS as a function of campaign exposure and household characteristics was evaluated using ordinal logistic regression models. Standardised, community-level SODIS-implementation in a rural Bolivian setting was associated with a median SODIS use of 32% (IQR: 17-50). Households that were more likely to use SODIS were those that participated more frequently in SODIS promotional events (OR=1.07, 95%CI: 1.01-1.13), included women (OR=1.18, 95%CI: 1.07-1.30), owned latrines (OR=3.38, 95%CI: 1.07-10.70), and had severely wasted children living in the home (OR=2.17, 95%CI: 1.34-3.49). Most of the observed household characteristics showed limited potential to predict compliance with a comprehensive, year-long SODIS-promotion campaign; this finding reflects the complexity of behaviour change in the context of household water treatment. However, our findings also suggest that the motivation to adopt new water treatment habits and to acquire new knowledge about drinking water treatment is associated with prior engagements in sanitary hygiene and with the experience of contemporary family health concerns

  14. Factors associated with compliance among users of solar water disinfection in rural Bolivia

    Directory of Open Access Journals (Sweden)

    Cevallos Myriam

    2011-04-01

    Full Text Available Abstract Background Diarrhoea is the second leading cause of childhood mortality, with an estimated 1.3 million deaths per year. Promotion of Solar Water Disinfection (SODIS has been suggested as a strategy for reducing the global burden of diarrhoea by improving the microbiological quality of drinking water. Despite increasing support for the large-scale dissemination of SODIS, there are few reports describing the effectiveness of its implementation. It is, therefore, important to identify and understand the mechanisms that lead to adoption and regular use of SODIS. Methods We investigated the behaviours associated with SODIS adoption among households assigned to receive SODIS promotion during a cluster-randomized trial in rural Bolivia. Distinct groups of SODIS-users were identified on the basis of six compliance indicators using principal components and cluster analysis. The probability of adopting SODIS as a function of campaign exposure and household characteristics was evaluated using ordinal logistic regression models. Results Standardised, community-level SODIS-implementation in a rural Bolivian setting was associated with a median SODIS use of 32% (IQR: 17-50. Households that were more likely to use SODIS were those that participated more frequently in SODIS promotional events (OR = 1.07, 95%CI: 1.01-1.13, included women (OR = 1.18, 95%CI: 1.07-1.30, owned latrines (OR = 3.38, 95%CI: 1.07-10.70, and had severely wasted children living in the home (OR = 2.17, 95%CI: 1.34-3.49. Conclusions Most of the observed household characteristics showed limited potential to predict compliance with a comprehensive, year-long SODIS-promotion campaign; this finding reflects the complexity of behaviour change in the context of household water treatment. However, our findings also suggest that the motivation to adopt new water treatment habits and to acquire new knowledge about drinking water treatment is associated with prior engagements in sanitary

  15. [Substantiation of both safety indices for control over the use of chemicals for water disinfection and need to harmonize them with international requirements].

    Science.gov (United States)

    Tul'skaia, E A; Rakhmanin, Iu A; Zholdakova, Z I

    2012-01-01

    The domestic and also foreign indices applied for control over the safety of chemical disinfecting of water are considered. The data confirming need of extension of the list of legislatively approved indices are provided of water, efficiency and safety indicators, harmful impurity, transformation products. On the basis of the performed analysis of literature data and own investigations the following indices for inclusion in the processed. Sanitary standards and rules on drinking water are suggested: the total content of THM, the total content of haloacetic acids, the total maintenance of up to AHC index (adsorbed halogen-containing organic compounds) in water chlorination; chlorite- and chlorate ions in application of dioxide of chlorine; control over efficiency of water disinfection up to the steadiest microorganisms depending on an applied method. Introduction of settlement about necessity of control over the content of dangerous monomers and impurities in a commodity products in application of polymeric reagents and means of water disinfection is proved.

  16. A new method to prevent the corrosion of dental metals, during disinfection using functional water: sacrificial protection.

    Science.gov (United States)

    Kashiwabara, Toshiya; Goto, Takaharu; Sato, Yutaka; Tomotake, Yoritoki; Nagao, Kan; Ichikawa, Tetsuo

    2010-07-01

    This paper demonstrates a simple method using sacrificial protection for preventing the corrosion of dental metals. Dental metals are directly connected or/and wound with a pure commercial aluminum/zinc wire/plate with high ionization tendency, before their immersion into oxidizing functional water. Dental materials such as Co-Cr alloy wires, stainless steel, and Au-Ag-Pd alloys did not corrode when this method was used. Thus, this method is very simple and effective for preventing corrosion of dental metals during disinfection using functional water. Copyright 2010 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  17. Application of an electrochemical chlorine-generation system combined with solar energy as appropriate technology for water disinfection.

    Science.gov (United States)

    Choi, Jusol; Park, Chan Gyu; Yoon, Jeyong

    2013-02-01

    Affordable water disinfection is key to reducing the waterborne disease experienced worldwide where resources are limited. A simple electrochemical system that can generate chlorine as a disinfectant from the electrolysis of sodium chloride is an appropriate technology to produce clean water, particularly if driven by solar energy. This study examined the affordability of an electrochemical chlorine generation system using solar energy and developed the necessary design information for its implementation. A two-electrode batch reactor, equipped with commercial IrO(2)-coated electrodes and a solar panel (approximate area 0.2 m(2)), was used to produce chlorine from a 35g/L solution of NaCl. Within 1 h, sufficient chlorine (0.8 g) was generated to produce clean drinking water for about 80 people for 1 day (target microorganism: Escherichia coli; daily drinking water requirement: 2 L per person; chlorine demand: 4 mg/L; solar power: 650 W/m(2) in Seoul, Korea. Small household batteries were demonstrated to be a suitable alternative power source when there is insufficient solar irradiation. Using a 1 m(2) solar panel, the reactor would take only 15 min in Seoul, Korea, or 7 min in the tropics (solar power 1300 W/m(2)), to generate 1 g of chlorine. The solar-powered electrochemical chlorine generation system for which design information is provided here is a simple and affordable way to produce chlorine with which to convert contaminated water into clean drinking water.

  18. Shift in the microbial ecology of a hospital hot water system following the introduction of an on-site monochloramine disinfection system.

    Science.gov (United States)

    Baron, Julianne L; Vikram, Amit; Duda, Scott; Stout, Janet E; Bibby, Kyle

    2014-01-01

    Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital's hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.

  19. Solar water disinfection (SODIS) of Escherichia coli, Enterococcus spp., and MS2 coliphage: effects of additives and alternative container materials.

    Science.gov (United States)

    Fisher, Michael B; Iriarte, Mercedes; Nelson, Kara L

    2012-04-15

    The use of alternative container materials and added oxidants accelerated the inactivation of MS2 coliphage and Escherichia coli and Enterococcus spp. bacteria during solar water disinfection (SODIS) trials. Specifically, bottles made from polypropylene copolymer (PPCO), a partially UVB-transparent plastic, resulted in three-log inactivation of these organisms in approximately half the time required for disinfection in bottles made from PET, polycarbonate, or Tritan(®), which absorb most UVB light. Furthermore, the addition of 125 mg/L sodium percarbonate in combination with either citric acid or copper plus ascorbate tended to accelerate inactivation by factors of 1.4-19. Finally, it was observed that the inactivation of E. coli and enterococci derived from local wastewater was far slower than the inactivation of laboratory-cultured E. coli and Enterococcus spp., while the inactivation of MS2 was slowest of all. These results highlight the importance of UVB in SODIS under certain conditions, and also the greater sunlight resistance of some viruses and of bacteria of fecal origin, as compared to the laboratory-cultured bacteria commonly used to model their inactivation. Furthermore, this study illustrates promising new avenues for accelerating the inactivation of bacteria and viruses by solar disinfection. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Glutathione-mediated detoxification of halobenzoquinone drinking water disinfection byproducts in T24 cells.

    Science.gov (United States)

    Li, Jinhua; Wang, Wei; Zhang, Hongquan; Le, X Chris; Li, Xing-Fang

    2014-10-01

    Halobenzoquinones (HBQs) are a new class of drinking water disinfection byproducts (DBPs) and are capable of producing reactive oxygen species and causing oxidative damage to proteins and DNA in T24 human bladder carcinoma cells. However, the exact mechanism of the cytotoxicity of HBQs is unknown. Here, we investigated the role of glutathione (GSH) and GSH-related enzymes including glutathione S-transferase (GST) and glutathione peroxidase (GPx) in defense against HBQ-induced cytotoxicity in T24 cells. The HBQs are 2,6-dichloro-1,4-benzoquinone (DCBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), 2,3,6-trichloro-1,4-benzoquinone (TriCBQ), and 2,6-dibromobenzoquinone (DBBQ). We found that depletion of cellular GSH could sensitize cells to HBQs and extracellular GSH supplementation could attenuate HBQ-induced cytotoxicity. HBQs caused significant cellular GSH depletion and increased cellular GST activities in a concentration-dependent manner. Our mass spectrometry study confirms that HBQs can conjugate with GSH, explaining in part the mechanism of GSH depletion by HBQs. The effects of HBQs on GPx activity are compound dependent; DCMBQ and DBBQ decrease cellular GPx activities, whereas DCBQ and TriCBQ have no significant effects. Pearson correlation analysis shows that the cellular GSH level is inversely correlated with ROS production and cellular GST activity in HBQ-treated cells. These results support a GSH and GSH-related enzyme-mediated detoxification mechanism of HBQs in T24 cells. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Application of solar disinfection for treatment of contaminated public water supply in a developing country: field observations.

    Science.gov (United States)

    Mustafa, Atif; Scholz, Miklas; Khan, Sadia; Ghaffar, Abdul

    2013-03-01

    A sustainable and low-cost point-of-use household drinking water solar disinfection (SODIS) technology was successfully applied to treat microbiologically contaminated water. Field experiments were conducted to determine the efficiency of SODIS and evaluate the potential benefits and limitations of SODIS under local climatic conditions in Karachi, Pakistan. In order to enhance the efficiency of SODIS, the application of physical interventions were also investigated. Twenty per cent of the total samples met drinking water guidelines under strong sunlight weather conditions, showing that SODIS is effective for complete disinfection under specific conditions. Physical interventions, including black-backed and reflecting rear surfaces in the batch reactors, enhanced SODIS performance. Microbial regrowth was also investigated and found to be more controlled in reactors with reflective and black-backed surfaces. The transfer of plasticizer di(2-ethylhexyl)phthalate (DEHP) released from the bottle material polyethylene terephthalate (PET) under SODIS conditions was also investigated. The maximum DEHP concentration in SODIS-treated water was 0.38 μg/L less than the value of 0.71 μg/L reported in a previous study and well below the WHO drinking-quality guideline value. Thus SODIS-treated water can successfully be used by the people living in squatter settlements of mega-cities, such as Karachi, with some limitations.

  2. A review on wastewater disinfection

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Amin

    2013-01-01

    Full Text Available Changes in regulations and development of new technologies have affected the selection of alternative for treated wastewater disinfection. Disinfection is the last barrier of wastewater reclamation process to protect ecosystem safety and human health. Driving forces include water scarcity and drinking water supply, irrigation, rapid industrialization, using reclaimed water, source protection, overpopulation, and environmental protection. The safe operation of water reuse depends on effluent disinfection. Understanding the differences in inactivation mechanisms is critical to identify rate-limiting steps involved in the inactivation process as well as to develop more effective disinfection strategies. Disinfection byproducts discharged from wastewater treatment plants may impair aquatic ecosystems and downstream drinking-water quality. Numerous inorganic and organic micropollutants can undergo reactions with disinfectants. Therefore, to mitigate the adverse effects and also to enhance that efficiency, the use of alternative oxidation/disinfection systems should be evaluated as possible alternative to chlorine. This review gives a summary of the traditional, innovative, and combined disinfection alternatives and also disinfection byproducts for effluent of municipal wastewater treatment plants.

  3. Magnetically Recoverable and Reusable Antimicrobial Nanocomposite Based on Activated Carbon, Magnetite Nanoparticles, and Silver Nanoparticles for Water Disinfection

    Directory of Open Access Journals (Sweden)

    Ping Y. Furlan

    2017-06-01

    Full Text Available Recent advancements in nanotechnology have led to the development of innovative, low-cost and highly efficient water disinfection technologies that may replace or enhance the conventional methods. In this study, we introduce a novel procedure for preparing a bifunctional activated carbon nanocomposite in which nanoscale-sized magnetic magnetite and antimicrobial silver nanoparticles are incorporated (MACAg. The antimicrobial efficacy of the nanocomposite was tested against Escherichia coli (E. coli. MACAg (0.5 g, 0.04% Ag was found to remove and kill 106–107 CFU (colony-forming units in 30 min via a shaking test and the removing and killing rate of the nanocomposites increased with increasing silver content and decreased with increasing CFU. The inhibition zone tests revealed, among the relevant components, only Ag nanoparticles and Ag+ ions showed antimicrobial activities. The MACAg was easily recoverable from treated water due to its magnetic properties and was able to remove and kill 106 CFU after multiple-repeated use. The MACAg nanocomposite also demonstrated its feasibility and applicability for treating a surface water containing 105 CFU. Combining low cost due to easy synthesis, recoverability, and reusability with high antimicrobial efficiency, MACAg may provide a promising water disinfection technology that will find wide applications.

  4. Modelling formation of disinfection by-products in water distribution: Optimisation using a multi-objective evolutionary algorithm

    KAUST Repository

    Radhakrishnan, Mohanasundar

    2012-05-01

    Concerns have been raised regarding disinfection by-products (DBPs) formed as a result of the reaction of halogen-based disinfectants with DBP precursors. In order to appreciate the chemical and biological tradeoffs, it is imperative to understand the formation trends of DBPs and their spread in the distribution network. However, the water at a point in a complex distribution system is a mixture from various sources, whose proportions are complex to estimate and requires advanced hydraulic analysis. To understand the risks of DBPs and to develop mitigation strategies, it is important to understand the distribution of DBPs in a water network, which requires modelling. The goal of this research was to integrate a steady-state water network model with a particle backtracking algorithm and chlorination as well as DBPs models in order to assess the tradeoffs between biological and chemical risks in the distribution network. A multi-objective optimisation algorithm was used to identify the optimal proportion of water from various sources, dosages of alum, and dosages of chlorine in the treatment plant and in booster locations to control the formation of chlorination DBPs and to achieve a balance between microbial and chemical risks. © IWA Publishing 2012.

  5. Models for estimation of the presence of non-regulated disinfection by-products in small drinking water systems.

    Science.gov (United States)

    Guilherme, Stéphanie; Rodriguez, Manuel J

    2017-10-23

    Among all the organic disinfection by-products (DBPs), only trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated in drinking water, while most DBPs are not. Very little information exists on the occurrence of non-regulated DBPs, particularly in small water systems (SWS). Paradoxically, SWS are more vulnerable to DBPs because of a low capacity to implement adequate treatment technologies to remove DBP precursors. Since DBP analyses are expensive, usually SWS have difficulties to implement a rigorous characterization of these contaminants. The purpose of this study was to estimate non-regulated DBP levels in SWS from easy measurements of relevant parameters regularly monitored. Since no information on non-regulated DBPs in SWS was available, a sampling program was carried out in 25 SWS in two provinces of Canada. Five DBP families were investigated: THMs, HAAs, haloacetonitriles (HANs), halonitromethanes (HNMs), and haloketones (HKs). Multivariate linear mixed regression models were developed to estimate HAN, HK, and HNM levels from water quality characteristics in the water treatment plant, concentrations of regulated DBPs, and residual disinfectant levels. The models obtained have a good explanatory capacity since R (2) varies from 0.77 to 0.91 according to compounds and conditions for application (season and type of treatment). Model validation with an independent database suggested their ability for generalization in similar SWS in North America.

  6. Solar water disinfection (SODIS): A review from bench-top to roof-top

    CSIR Research Space (South Africa)

    McGuigan, KG

    2012-10-01

    Full Text Available it faster and safer. Since SODIS is simple to use and inexpensive, the method has spread throughout the developing world and is in daily use in more than 50 countries in Asia, Latin America, and Africa. More than 5 million people disinfect their drinking...

  7. [Degradation Kinetics and Formation of Disinfection By-products During Linuron Chlorination in Drinking Water].

    Science.gov (United States)

    Ling, Xiao; Hu, Chen-yan; Cheng, Ming; Gu, Jian

    2015-05-01

    Chlorination degradation of linuron was studied using the common disinfectant sodium hypochlorite, the effects of chlorine dosage, pH value, bromine ion concentrationand temperature were systematically investigated, and the formation characteristics of disinfection by-products (DBPs) during the chlorination reaction was analyzed. The results showed that the chlorination degradation kinetics of linuron by sodium hypochlorite could be well described by the second-order kinetic model. Moreover, pH values had a great impact on the degradation reaction, and the rate constant reached the maximum level at pH 7, and the base elementary reaction rate constants of HOCl and OCl- with linuron were 4.84 x 10(2) L · (mol · h)(-1) and 3.80 x 10(2) L · (mol · h)(-1), respectively. The reaction rate decreased with the addition of bromide ion and increased with increasing temperature. Furthermore, many kinds of disinfection by- products were produced during the chlorination degradation of linuron, including CF, DCAN, TCNM and halogen acetone. Under conditions of different solution pH and different bromide ion concentrations, there would be significant difference in the types and concentrations of disinfection by-products.

  8. Comet assay and micronucleus test in circulating erythrocytes of Cyprinus carpio specimens exposed in situ to lake waters treated with disinfectants for potabilization.

    Science.gov (United States)

    Buschini, A; Martino, A; Gustavino, B; Monfrinotti, M; Poli, P; Rossi, C; Santoro, M; Dörr, A J M; Rizzoni, M

    2004-02-14

    The detection of a possible genotoxic effect of surface water treated with disinfectants for potabilization is the aim of the present work. The Comet assay and the micronucleus test were applied in circulating erythrocytes of Cyprinus carpio. Young specimens (20-30 g) were exposed in experimental basins, built within the potabilization plant of Castiglione del Lago (Perugia, Italy). In this plant the water of the Trasimeno Lake is treated and disinfected for potabilization before it is distributed to the people in the net of drinkable water. A continuous flow of water at a constant rate was supplied to basins; the water was continuously treated at a constant concentration with one of the three tested disinfectants (sodium hypochlorite, peracetic acid and chloride dioxide), one control basin being supplied with untreated water. Three sampling campaigns were performed: October 2000, February 2001 and June 2001. Repeated blood samplings through intracardiac punctures allowed to follow the same fish populations after different exposure times: before introduction of the disinfectant, and 10 or 20 days afterwards. An additional blood sampling was performed 3 h after addition of the disinfectant in other, simultaneously exposed, fish populations. Genotoxic damage was shown in fish exposed to water disinfected with sodium hypochlorite and chloride dioxide. The Comet assay showed an immediate response, i.e. DNA damage that was induced directly in circulating erythrocytes, whereas micronuclei reached their highest frequencies at later sampling times, when a genotoxic damage in stem cells of the cephalic kidney is expressed in circulating erythrocytes. The quality of the untreated surface water seems to be the most important parameter for the long-term DNA damage in circulating erythrocytes.

  9. Characterization and disinfection by-product formation potential of natural organic matter in surface and ground waters from Northern Florida

    Science.gov (United States)

    Rostad, C.E.; Leenheer, J.A.; Katz, B.; Martin, B.S.; Noyes, T.I.

    2000-01-01

    Streamwaters in northern Florida have large concentrations of natural organic matter (NOM), and commonly flow directly into the ground water system through karst features, such as sinkholes. In this study NOM from northern Florida stream and ground waters was fractionated, the fractions characterized by infrared (IR) and nuclear magnetic resonance (NMR), and then chlorinated to investigate their disinfection by-product (DBP) formation potential (FP). As the NOM character changed (as quantified by changes in NOM distribution in various fractions, such as hydrophilic acids or hydrophobic neutrals) due to migration through the aquifer, the total organic halide (TOX)-FP and trihalomethane (THM)-FP yield of each of these fractions varied also. In surface waters, the greatest DBP yields were produced by the colloid fraction. In ground waters, DBP yield of the hydrophobic acid fraction (the greatest in terms of mass) decreased during infiltration.

  10. Water disinfection and hygiene behaviour in an urban slum in Kenya: impact on childhood diarrhoea and influence of beliefs.

    Science.gov (United States)

    Graf, Jürg; Meierhofer, Regula; Wegelin, Martin; Mosler, Hans-Joachim

    2008-10-01

    In this research project, we studied factors that presumably affect the incidence of diarrhoea among young children in urban slums in developing countries: consumption of safe drinks, hygiene behaviour, cleanliness of household surroundings and the quality of raw water. Beliefs concerning the causes of diarrhoea were also related to health-improving behaviour, namely the application of the water-treatment method SODIS (solar water disinfection) and hygiene behaviour. We conducted a survey in a shanty town in Nairobi, Kenya. Field workers interviewed 500 households. Analysis with regression models revealed that two out of the four postulated factors were significant: children have a lower risk of contracting diarrhoea when they consume high percentages of safe drinks and live in households with good hygiene. As regards beliefs, we found that biomedical knowledge of children's diarrhoea as well as the perceived social norm for treating water was associated with the use of SODIS and good hygiene.

  11. UV/TiO2 photocatalytic disinfection of carbon-bacteria complexes in activated carbon-filtered water: Laboratory and pilot-scale investigation.

    Science.gov (United States)

    Zhao, Jin Hui; Chen, Wei; Zhao, Yaqian; Liu, Cuiyun; Liu, Ranbin

    2015-01-01

    The occurrence of carbon-bacteria complexes in activated carbon filtered water has posed a public health problem regarding the biological safety of drinking water. The application of combined process of ultraviolet radiation and nanostructure titanium dioxide (UV/TiO2) photocatalysis for the disinfection of carbon-bacteria complexes were assessed in this study. Results showed that a 1.07 Lg disinfection rate can be achieved using a UV dose of 20 mJ cm(-2), while the optimal UV intensity was 0.01 mW cm(-2). Particle sizes ≥8 μm decreased the disinfection efficiency, whereas variation in particle number in activated carbon-filtered water did not significantly affect the disinfection efficiency. Photoreactivation ratio was reduced from 12.07% to 1.69% when the UV dose was increased from 5 mJ cm(-2) to 20 mJ cm(-2). Laboratory and on-site pilot-scale experiments have demonstrated that UV/TiO2 photocatalytic disinfection technology is capable of controlling the risk posed by carbon-bacteria complexes and securing drinking water safety.

  12. Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments

    Science.gov (United States)

    Mitchell, A.J.; Cole, Rebecca A.

    2008-01-01

    The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region and Montana. It is important to limit the spread of the faucet snail; small fisheries equipment can serve as a method of snail distribution. Treatments with chemical disinfection, pH extremes, and heated water baths were tested to determine their effectiveness as a disinfectant for small fisheries equipment. Two treatments eliminated all test snails: (1) a 24-h exposure to Hydrothol 191 at a concentration of at least 20 mg/L and (2) a treatment with 50°C heated water for 1 min or longer. Faucet snails were highly resistant to ethanol, NaCl, formalin, Lysol, potassium permanganate, copper sulfate, Baquacil, Virkon, household bleach, and pH extremes (as low as 1 and as high as 13).

  13. Factors involved in sustained use of point-of-use water disinfection methods: a field study from Flores Island, Indonesia.

    Science.gov (United States)

    Roma, E; Bond, T; Jeffrey, P

    2014-09-01

    Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients' acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase. This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government). Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies.

  14. Inactivation and injury of total coliform bacteria after primary disinfection of drinking water by TiO{sub 2} photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, Luigi, E-mail: l.rizzo@unisa.it [Department of Civil Engineering, University of Salerno, 84084 Fisciano (Italy)

    2009-06-15

    In this study the potential application of TiO{sub 2} photocatalysis as primary disinfection system of drinking water was investigated in terms of coliform bacteria inactivation and injury. As model water the effluent of biological denitrification unit for nitrate removal from groundwater, which is characterized by high organic matter and bacteria release, was used. The injury of photocatalysis on coliform bacteria was characterized by means of selective (mEndo) and less selective (mT7) culture media. Different catalyst loadings as well as photolysis and adsorption effects were investigated. Photocatalysis was effective in coliform bacteria inactivation (91-99% after 60 min irradiation time, depending on both catalyst loading and initial density of coliform bacteria detected by mEndo), although no total removal was observed after 60 min irradiation time. The contribution of adsorption mechanism was significant (60-98% after 60 min, depending on catalyst loading) compared to previous investigations probably due to the nature of source water rich in particulate organic matter and biofilm. Photocatalysis process did not result in any irreversible injury (98.8% being the higher injury) under investigated conditions, thus a bacteria regrowth may take place under optimum environment conditions if any final disinfection process (e.g., chlorine or chlorine dioxide) is not used.

  15. Determination of the minor disinfection by-products formed in the water plant of Sant Joan Despi (Barcelona, Spain); Determinacion de los subproductos de desinfeccion minoritarios formados en la planta de Sant Joan Despi (Barcelona)

    Energy Technology Data Exchange (ETDEWEB)

    Cancho, B.; Galceran, M.T. [Universitat de Barcelona (Spain); Ventura, F. [AGBAR. Societat General d` Aigues de Barcelona, S.A. (Spain)

    1997-09-01

    Chlorine is widely used in drinking water disinfection due to be a powerful and not expense disinfection. Although the benefits of disinfection, the formation of stable disinfection by-products of the health concern, is the result of the interaction of aqueous chlorine with natural organic matter presents in water. Disinfection by-products generated in major concentration are trihalomethane and haloacetic acids. Disinfection by-products generated in minor concentration are haloacetonitriles, haloketones,chloral hydrate and chloropicrin and some new groups such as cyanogen halides and trihaloacetaldydes. In this work two analytical methods.: headspace/gas chromatography/electron capture detector and liquid-liquid microextraction/gas chromatography/electron capture detector are studied and compared to determine the minor by-products and to establish finally, a systematic control of them in the different stages of the Water Treatment Plant of San Joan Despi (Barcelona, Spain). (Author) 12 refs.

  16. Decontamination of Bacillus spores adhered to iron and cement-mortar drinking water infrastructure in a model system using disinfectants.

    Science.gov (United States)

    Szabo, Jeffrey G; Meiners, Greg; Heckman, Lee; Rice, Eugene W; Hall, John

    2017-02-01

    Decontamination of Bacillus spores adhered to common drinking water infrastructure surfaces was evaluated using a variety of disinfectants. Corroded iron and cement-mortar lined iron represented the infrastructure surfaces, and were conditioned in a 23 m long, 15 cm diameter (75 ft long, 6 in diameter) pilot-scale drinking water distribution pipe system. Decontamination was evaluated using increased water velocity (flushing) alone at 0.5 m s(-1) (1.7 ft s(-1)), as well as free chlorine (5 and 25 mg L(-1)), monochloramine (25 mg L(-1)), chlorine dioxide (5 and 25 mg L(-1)), ozone (2.0 mg L(-1)), peracetic acid 25 mg L(-1)) and acidified nitrite (0.1 mol L(-1) at pH 2 and 3), all followed by flushing at 0.3 m s(-1) (1 ft s(-1)). Flushing alone reduced the adhered spores by 0.5 and 2.0 log10 from iron and cement-mortar, respectively. Log10 reduction on corroded iron pipe wall coupons ranged from 1.0 to 2.9 at respective chlorine dioxide concentrations of 5 and 25 mg L(-1), although spores were undetectable on the iron surface during disinfection at 25 mg L(-1). Acidified nitrite (pH 2, 0.1 mol L(-1)) yielded no detectable spores on the iron surface during the flushing phase after disinfection. Chlorine dioxide was the best performing disinfectant with >3.0 log10 removal from cement-mortar at 5 and 25 mg L(-1). The data show that free chlorine, monochloramine, ozone and chlorine dioxide followed by flushing can reduce adhered spores by > 3.0 log10 on cement-mortar. Published by Elsevier Ltd.

  17. INTERRELATIONSHIPS AMONG EPIGENETIC MECHANISMS FOR RISK ASSESSMENT OF DICHLOROACETIC ACID, A DRINKING WATER BY-PRODUCT OF THE CHLORINE DISINFECTION PROCESS

    Science.gov (United States)

    The reauthorization of The Safe Drinking Water Act of 1996 requires the EPA to develop a priority list of chemicals that are present in drinking water and to conduct research into the modes and mechanisms of action by which they produce adverse effects. The disinfection by-produc...

  18. Assessing spatial fluctuations, temporal variability, and measurement error in estimated levels of disinfection by-products in tap water: implications for exposure assessment

    OpenAIRE

    Symanski, E; Savitz, D; Singer, P

    2004-01-01

    Aims: To assess spatial fluctuations, temporal variability, and errors due to sampling and analysis in levels of disinfection by-products in routine monitoring tap water samples and in water samples collected in households within the same distribution system for an exposure assessment study.

  19. Solar and photocatalytic disinfection of protozoan, fungal and bacterial microbes in drinking water.

    Science.gov (United States)

    Lonnen, J; Kilvington, S; Kehoe, S C; Al-Touati, F; McGuigan, K G

    2005-03-01

    The ability of solar disinfection (SODIS) and solar photocatalytic (TiO(2)) disinfection (SPC-DIS) batch-process reactors to inactivate waterborne protozoan, fungal and bacterial microbes was evaluated. After 8 h simulated solar exposure (870 W/m(2) in the 300 nm-10 microm range, 200 W/m(2) in the 300-400 nm UV range), both SPC-DIS and SODIS achieved at least a 4 log unit reduction in viability against protozoa (the trophozoite stage of Acanthamoeba polyphaga), fungi (Candida albicans, Fusarium solani) and bacteria (Pseudomonas aeruginosa, Escherichia coli). A reduction of only 1.7 log units was recorded for spores of Bacillus subtilis. Both SODIS and SPC-DIS were ineffective against the cyst stage of A. polyphaga.

  20. Safe drinking water and clean air: an experimental study evaluating the concept of combining household water treatment and indoor air improvement using the Water Disinfection Stove (WADIS).

    Science.gov (United States)

    Christen, Andri; Navarro, Carlos Morante; Mäusezahl, Daniel

    2009-09-01

    Indoor air pollution and unsafe water remain two of the most important environmental risk factors for the global burden of infectious diseases. Improved stoves and household water treatment (HWT) methods represent two of the most effective interventions to fight respiratory and diarrhoeal illnesses at household level. Since new improved stoves are highly accepted and HWT methods have their drawbacks regarding sustained use, combining the two interventions in one technical solution could result in notable positive convenience and health benefits. A WAter DIsinfection Stove (WADIS) based on a Lorena-stove design with a simple flow-through boiling water-treatment system was developed and tested by a pilot experimental study in rural Bolivia. The results of a post-implementation evaluation of two WADIS and 27 Lorena-stoves indicate high social acceptance rather due to convenience gains of the stove than to perceived health improvements. The high efficacy of the WADIS-water treatment system, with a reduction of microbiological contamination load in the treated water from 87600 thermotolerant coliform colony forming units per 100mL (CFU/100mL) to zero is indicative. The WADIS concept unifies two interventions addressing two important global burdens of disease. WADIS' simple design, relying on locally available materials and low manufacturing costs (approx. 6 US) indicates potential for spontaneous diffusion and scaling up.

  1. Promotion of solar water disinfection: comparing the effectiveness of different strategies in a longitudinal field study in Bolivia.

    Science.gov (United States)

    Tamas, Andrea; Tobias, Robert; Mosler, Hans-Joachim

    2009-12-01

    Solar water disinfection (SODIS) is a simple method designed to treat microbiologically contaminated drinking water at the household level. This study focused on the effective promotion of the SODIS method using various strategies. In a longitudinal field study, we compared 2 interpersonal strategies (promoters and opinion leaders) and a centralized strategy (health fair) with a control group. Indicators of effectiveness were SODIS knowledge, SODIS adoption rate, and potential reach. The results suggest that use of promoters is the most successful strategy in terms of reaching people and changing their behavior toward SODIS use. The opinion leaders-although less effective-show some potential to stimulate communication among people about SODIS. Only the health fair did not have a big impact on behavior. Further discussion includes the costs of the various promotional activities, limitations, and recommendations for future projects.

  2. Modelling of Disinfection by-products formation via UV irradiation of the water from Tajan River (source water for Sari drinking water, Iran

    Directory of Open Access Journals (Sweden)

    Allahbakhsh Javid

    2013-11-01

    Full Text Available Background & Aims of the Study Irradiation with ultraviolet light (UV is used for the disinfection of bacterial contaminants in the production of potable water. The main objective of the study was to investigate and model Disinfection By-Products (DBPs formation due to the UV Irradiation of the Tajan River water under different Irradiation conditions. Materials & Methods:  Water samples were collected throughout September 2011 to August 2013. Transportation of the sample to the laboratory was done on ice in a cooler, and physiochemical analysis was conducted immediately within one day. Dissolved organic carbon (DOC was determined by a TOC analyzer. Irradiation experiments were conducted in a series of 25 mL glass serum bottles with Teflon septa. The present study adopts an orthogonal design. The design involved irradiation with UV at a UV/DOC ratio of 0.5–3.0 and incubating (headspace-free storage for 5–25 sec. A 1 mM phosphate buffer maintained the pH at 6, 7, or 8 respectively, and an incubator maintained the temperature (Temp at 15, 20, or 25 °C respectively. The development of empirical models for DBPs formation used a multivariate regression procedure (stepwise which applied the SPSS System for Windows (Version 16.0. Results:  The results showed that the total DBPs formation ranged between 12.3 and 67.4 mg/l and that control of the levels was primarily due to the reaction time and the dissolved organic carbon level (DOC in the water. Conclusions:  Reaction time and level of DOC concentrations in water exerted a dominant influence on the formation of DBPs during the UV irradiation of water from the Tajan River. The relationships between the measured and predicted values were satisfactory with R 2 values ranging from 0.89 (for Octanal–0.92 (for Formaldehydes. The DOC level in water is the key factor in controlling DBPs formation.

  3. Shift in the microbial ecology of a hospital hot water system following the introduction of an on-site monochloramine disinfection system.

    Directory of Open Access Journals (Sweden)

    Julianne L Baron

    Full Text Available Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital's hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.

  4. Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region.

    Science.gov (United States)

    Ndounla, J; Pulgarin, C

    2014-09-15

    The photo-disinfection of water from two different wells (W1, pH: 4.6-5.1 ± 0.02) and (W2 pH: 5.6-5.7 ± 0.02) was carried out during the rainy season at Ouagadougou-Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO3(-) concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO3(-) concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and ammonia. Copyright © 2014 Elsevier B

  5. Surface water disinfection by chlorination and advanced oxidation processes: Inactivation of an antibiotic resistant E. coli strain and cytotoxicity evaluation.

    Science.gov (United States)

    Miranda, Andreza Costa; Lepretti, Marilena; Rizzo, Luigi; Caputo, Ivana; Vaiano, Vincenzo; Sacco, Olga; Lopes, Wilton Silva; Sannino, Diana

    2016-06-01

    The release of antibiotics into the environment can result in antibiotic resistance (AR) spread, which in turn can seriously affect human health. Antibiotic resistant bacteria have been detected in different aquatic environments used as drinking water source. Water disinfection may be a possible solution to minimize AR spread but conventional processes, such as chlorination, result in the formation of dangerous disinfection by-products. In this study advanced oxidation processes (AOPs), namely H2O2/UV, TiO2/UV and N-TiO2/UV, have been compared with chlorination in the inactivation of an AR Escherichia coli (E. coli) strain in surface water. TiO2 P25 and nitrogen doped TiO2 (N-TiO2), prepared by sol-gel method at two different synthesis temperatures (0 and -20°C), were investigated in heterogeneous photocatalysis experiments. Under the investigated conditions, chlorination (1.0 mg L(-1)) was the faster process (2.5 min) to achieve total inactivation (6 Log). Among AOPs, H2O2/UV resulted in the best inactivation rate: total inactivation (6 Log) was achieved in 45 min treatment. Total inactivation was not observed (4.5 Log), also after 120 min treatment, only for N-doped TiO2 synthesized at 0°C. Moreover, H2O2/UV and chlorination processes were evaluated in terms of cytotoxicity potential by means of 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenylte-trazolium colorimetric test on a human-derived cell line and they similarly affected HepG2 cells viability. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Study of process of water disinfection it saw energy solar using an experimental reactor; Estudo do proceso de desinfeccao de agua via energia solar utilizando um reator experimental

    Energy Technology Data Exchange (ETDEWEB)

    Batista, C. H.; Prado, L. R.; Lima, A. S.; Egues, S. M. S.; Araujo, P. M. M.

    2008-07-01

    In this work, was conducted an experimental study of the efficiency of a solar reactor in the disinfection of drinking water using photolysis (UV) and heterogeneous photo catalysis (TiO{sub 2}/UV). The experiments were conducted in batch mode, evaluating the effects of reactor inclination and the presence of a solar concentrator. The results indicated that the employed system was capable to promote the complete disinfection in 150 min using only the photo thermic effect, and in 120 min with the addition of immobilized TiO{sub 2} and the solar concentrator. (Author)

  7. MEETING IN CHINA: CHLORINATED VS. CHLORAMINATED DRINKING WATER: TOXICITY-BASED IDENTIFICATION OF DISINFECTION BY-PRODUCTS USING ESI-MS AND ESI-MS/MS

    Science.gov (United States)

    Drinking water disinfection by-products (DBPs) are of concern because epidemiologic studies have shown that they are associated with bladder cancer and adverse reproductive/developmental effects in human populations, and some cause cancer in laboratory animals. As a result, the U...

  8. Effect of peracetic acid, ultraviolet radiation, nanofiltration-chlorine in the disinfection of a non conventional source of water (Tula Valley).

    Science.gov (United States)

    Trujillo, J; Barrios, J A; Jimenez, B

    2008-01-01

    Water supply for human consumption requires certain quality that reduces health risks to consumers. In this sense, the process of disinfection plays an important role in the elimination of pathogenic microorganisms. Even though chlorination is the most applied process based on its effectiveness and cost, its application is being questioned considering the formation of disinfection by-products (DBPs). Therefore, alternative disinfectants are being evaluated and some treatment processes have been proposed to remove DBPs precursors (organic matter. This paper reports the results of disinfection of a non conventional source of water (aquifer recharged unintentionally with raw wastewater) with peracetic acid (PAA) and ultraviolet radiation (UV) as well as nanofiltration (NF) followed by chlorination to produce safe drinking water. The results showed that a dose of 2 mg/L PAA was needed to eliminate total and faecal coliforms. For UV light, a dose of 12.40 mWs/cm2 reduced total and faecal coliforms below the detection limit. On the other hand, chlorine demand of water before NF was 1.1-1.3 mg/L with a trihalomethane formation potential (THMFP) of 118.62 microg/L, in contrast with chlorination after NF where the demand was 0.5 mg/L and THMFP of 17.64 microg/L. The recommended scheme is nanofiltration + chlorination.

  9. Hepatic antioxidant enzymes and total glutathione of Cyprinus carpio exposed to three disinfectants, chlorine dioxide, sodium hypochlorite and peracetic acid, for superficial water potabilization.

    Science.gov (United States)

    Elia, Antonia Concetta; Anastasi, Valeria; Dörr, Ambrosius Josef Martin

    2006-09-01

    This study was carried out in order to assess the effects of disinfectant-treatment on antioxidant response of Cyprinus carpio L. Therefore, enzymatic activities of glutathione S-transferases, glyoxalase I, glyoxalase II, glutathione peroxidases, glutathione reductase, catalase and total glutathione content of carp liver, exposed to surface water treated with three disinfectants for potabilization, sodium hypochlorite, chlorine dioxide and peracetic acid were investigated. Specimens of carp were exposed in four experimental tanks supplied with a continuous water flow from Lake Trasimeno (Italy), three of them treated with constant concentration of sodium hypochlorite, chlorine dioxide and peracetic acid, for 10 and 20 days, while the control tank was supplied with untreated lake water. Differences in biochemical parameters were observed in specimens following exposure to these disinfectants and mainly, chlorine compounds induced marked biochemical variations of carp liver, compared to those induced by peracetic acid treatment. Our results showed that antioxidant parameters of Cyprinus carpio could be used as biomarkers of oxidative stress when this species is exposed to disinfectants for water potabilization.

  10. Monitoring trihalomethanes and nitrogenous disinfection by-products in blending desalinated waters using solid-phase microextraction and gas chromatography.

    Science.gov (United States)

    González-Hernández, Providencia; Hernández-Padrón, Manuel; Pino, Verónica; Afonso, Ana M; Ayala, Juan H

    2017-04-01

    A simple and efficient method has been developed for the extraction and determination of 16 common volatile halogenated disinfection by-products (DBPs) (four trihalomethanes, six haloacetonitriles, and six halonitromethanes) in blending desalinated waters, using headspace solid-phase microextraction and gas chromatography with flame ionization detector (HS-SPME/GC-FID). After the optimization using factorial designs of the HS-SPME parameters (optimum: carboxen/polydimethylsiloxane such as fiber, extraction time of 60 min at 30°C, pH 7, addition of 40% (w/v) of sodium chloride, and desorption time of 2 min at 250°C), quantification limits ranged from 3.03 to 40.8 µg L(-1), and relative standard deviation (inter-day) were lower than 9.7% for all the target DBPs. Adequate relative recoveries (with the exception of chloronitromethane) were obtained even when spiking waters at low levels (25 µg L(-1)), with values between 83.1% and 119% for ultrapure water, and between 87.4% and 115% for blending desalinated waters, supporting in this way the applicability of the method. The influence of various dechlorinating agents on the stability of 16 DBPs in water was evaluated, with ammonium chloride being the most suitable inhibitor of residual chlorine and carrying out the analytical determination of DBPs within 48 h after sampling. Different blending desalinated water samples collected in the South of Tenerife Island (Spain) were successfully analyzed.

  11. Effect of pH on the formation of disinfection byproducts in swimming pool water – Is less THM better?

    DEFF Research Database (Denmark)

    Hansen, Kamilla Marie Speht; Willach, Sarah; Antoniou, Maria

    2012-01-01

    This study investigated the formation and predicted toxicity of different groups of disinfection byproducts (DBPs) from human exudates in relation to chlorination of pool water at different pH values. Specifically, the formation of the DBP groups trihalomethanes (THMs), haloacetic acids (HAAs......), haloacetonitriles (HANs) and trichloramine (NCl3), resulting from the chlorination of body fluid analog, were investigated at 6.0 ≤ pH ≤ 8.0. Either the initial concentration of active chorine or free chlorine was kept constant in the tested pH range. THM formation was reduced by decreasing pH but HAN, and NCl3...... formation increased at decreasing pH whereas the formation of HAAs remained constant. Under our experimental conditions, the formation of NCl3 (suspected asthma inducing compound) at pH = 6.0 was an order of magnitude higher than at pH = 7.5. Furthermore, the effect of the presence of bromide on DBP...

  12. Effect of the radiation intensity, water turbidity and exposure time on the survival of Cryptosporidium during simulated solar disinfection of drinking water.

    Science.gov (United States)

    Gómez-Couso, Hipólito; Fontán-Sainz, María; McGuigan, Kevin G; Ares-Mazás, Elvira

    2009-10-01

    The solar disinfection (SODIS) technique is a highly effective process that makes use of solar energy to inactivate pathogenic microorganisms in drinking water in developing countries. The pathogenic protozoan parasite Cryptosporidium parvum is often found in surface waters and is associated with waterborne outbreaks of cryptosporidiosis. In the present study, a complete multi-factorial mathematical model was used to investigate the combined effects of the intensity of solar radiation (200, 600 and 900W/m(2) in the 320nm to 10microm range), water turbidity (5, 100 and 300 NTU) and exposure time (4, 8 and 12h) on the viability and infectivity of C. parvum oocysts during simulated SODIS procedures at a constant temperature of 30 degrees C. All three factors had significant effects (p or =600W/m(2) and times of exposure between 8 and 12h were required to reduce the oocyst infectivity in water samples with different degrees of turbidity.

  13. Isolation of Bacillus subtilis as indicator in the disinfection of residual water by means of gamma radiation; Aislamiento de Bacillus subtilis como indicador en la desinfeccion de aguas residuales mediante radiacion gamma

    Energy Technology Data Exchange (ETDEWEB)

    Mata J, M.; Colin C, A. [Facultad de Quimica, UAEM, Paseo Colon esq. Tollocan s/n, Toluca, 50000 Estado de Mexico (Mexico); Lopez V, H.; Brena V, M.; Carrasco A, H.; Pavon R, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    In the attempt to get more alternatives of disinfection of residual water, the Bacillus subtilis was isolated by means of gamma radiation as a bio indicator of disinfection since it turned out to be resistant to the 5 KGy dose, comparing this one with other usual microorganisms as biondicators like E. coli and S typhimurium which turn out more sensitive to such dose. (Author)

  14. Real-time ArcGIS and heterotrophic plate count based chloramine disinfectant control in water distribution system.

    Science.gov (United States)

    Bai, Xiaohui; Zhi, Xinghua; Zhu, Huifeng; Meng, Mingqun; Zhang, Mingde

    2015-01-01

    This study investigates the effect of chloramine residual on bacteria growth and regrowth and the relationship between heterotrophic plate counts (HPCs) and the concentration of chloramine residual in the Shanghai drinking water distribution system (DWDS). In this study, models to control HPCs in the water distribution system and consumer taps are also developed. Real-time ArcGIS was applied to show the distribution and changed results of the chloramine residual concentration in the pipe system by using these models. Residual regression analysis was used to get a reasonable range of the threshold values that allows the chloramine residual to efficiently inhibit bacteria growth in the Shanghai DWDS; the threshold values should be between 0.45 and 0.5 mg/L in pipe water and 0.2 and 0.25 mg/L in tap water. The low residual chloramine value (0.05 mg/L) of the Chinese drinking water quality standard may pose a potential health risk for microorganisms that should be improved. Disinfection by-products (DBPs) were detected, but no health risk was identified.

  15. Evaluation of Drinking Water Disinfectant Byproducts Compliance Data as an Indirect Measure for Short-Term Exposure in Humans

    Directory of Open Access Journals (Sweden)

    Shahid Parvez

    2017-05-01

    Full Text Available In the absence of shorter term disinfectant byproducts (DBPs data on regulated Trihalomethanes (THMs and Haloacetic acids (HAAs, epidemiologists and risk assessors have used long-term annual compliance (LRAA or quarterly (QA data to evaluate the association between DBP exposure and adverse birth outcomes, which resulted in inconclusive findings. Therefore, we evaluated the reliability of using long-term LRAA and QA data as an indirect measure for short-term exposure. Short-term residential tap water samples were collected in peak DBP months (May–August in a community water system with five separate treatment stations and were sourced from surface or groundwater. Samples were analyzed for THMs and HAAs per the EPA (U.S. Environmental Protection Agency standard methods (524.2 and 552.2. The measured levels of total THMs and HAAs were compared temporally and spatially with LRAA and QA data, which showed significant differences (p < 0.05. Most samples from surface water stations showed higher levels than LRAA or QA. Significant numbers of samples in surface water stations exceeded regulatory permissible limits: 27% had excessive THMs and 35% had excessive HAAs. Trichloromethane, trichloroacetic acid, and dichloroacetic acid were the major drivers of variability. This study suggests that LRAA and QA data are not good proxies of short-term exposure. Further investigation is needed to determine if other drinking water systems show consistent findings for improved regulation.

  16. A low-energy intensive electrochemical system for the eradication of Escherichia coli from ballast water: process development, disinfection chemistry, and kinetics modeling.

    Science.gov (United States)

    Nanayakkara, K G Nadeeshani; Alam, A K M Khorshed; Zheng, Yu-Ming; Chen, J Paul

    2012-06-01

    The invasion of biological organisms via ballast water has created threats to the environment and human health. In this study, a cost-effective electrochemical disinfection reactor was developed to inactivate Escherichia coli, one of the IMO-regulated indicator microbes, in simulated ballast water. The complete inactivation of E. coli could be achieved within a very short time (150, 120, or 60 s) with an energy consumption as low as 0.0090, 0.0074 or 0.0035 kWh/m(3) for ballast water containing E. coli at concentrations of 10(8), 10(7) and 10(6) CFU/100 mL, respectively. Electrochemical chlorination was the major disinfection mechanism in chloride-abundant electrolytes, whereas oxidants such as ozone and free radicals contributed to 20% of the disinfection efficiency in chloride-free electrolytes. Moreover, a disinfection kinetics model was successfully developed to describe the inactivation of E. coli. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Development of a research strategy for integrated technology-based toxicological and chemical evaluation of complex mixtures of drinking water disinfection byproducts.

    Science.gov (United States)

    Simmons, Jane Ellen; Richardson, Susan D; Speth, Thomas F; Miltner, Richard J; Rice, Glenn; Schenck, Kathleen M; Hunter, E Sidney; Teuschler, Linda K

    2002-01-01

    Chemical disinfection of water is a major public health triumph of the 20th century. Dramatic decreases in both morbidity and mortality of waterborne diseases are a direct result of water disinfection. With these important public health benefits comes low-level, chronic exposure to a very large number of disinfection byproducts (DBPs), chemicals formed through reaction of the chemical disinfectant with naturally occurring inorganic and organic material in the source water. This article provides an overview of joint research planning by scientists residing within the various organizations of the U.S. Environmental Protection Agency Office of Research and Development. The purpose is to address concerns related to potential health effects from exposure to DBPs that cannot be addressed directly from toxicological studies of individual DBPs or simple DBP mixtures. Two factors motivate the need for such an investigation of complex mixtures of DBPs: a) a significant amount of the material that makes up the total organic halide and total organic carbon portions of the DBPs has not been identified; and b) epidemiologic data, although not conclusive, are suggestive of potential developmental, reproductive, or carcinogenic health effects in humans exposed to DBPs. The plan is being developed and the experiments necessary to determine the feasibility of its implementation are being conducted by scientists from the National Health and Environmental Effects Research Laboratory, the National Risk Management Research Laboratory, the National Exposure Research Laboratory, and the National Center for Environmental Assessment. PMID:12634133

  18. Point-of-Use Removal of Cryptosporidium parvum from Water: Independent Effects of Disinfection by Silver Nanoparticles and Silver Ions and by Physical Filtration in Ceramic Porous Media.

    Science.gov (United States)

    Abebe, Lydia S; Su, Yi-Hsuan; Guerrant, Richard L; Swami, Nathan S; Smith, James A

    2015-11-03

    Ceramic water filters (CWFs) impregnated with silver nanoparticles are a means of household-level water treatment. CWFs remove/deactivate microbial pathogens by employing two mechanisms: metallic disinfection and physical filtration. Herein we report on the independent effects of silver salt and nanoparticles on Cryptosporidium parvum and the removal of C. parvum by physical filtration in porous ceramic filter media. Using a murine (mouse) model, we observed that treatment of oocysts with silver nitrate and proteinate-capped silver nanoparticles resulted in decreased infection relative to untreated oocysts. Microscopy and excystation experiments were conducted to support the disinfection investigation. Heat and proteinate-capped silver-nanoparticle treatment of oocysts resulted in morphological modifications and decreased excystation rates of sporozoites. Subsequently, disk-shaped ceramic filters were produced to investigate the transport of C. parvum. Two factors were varied: sawdust size and clay-to-sawdust ratio. Five disks were prepared with combinations of 10, 16, and 20 mesh sawdust and sawdust percentage that ranged from 9 to 11%. C. parvum removal efficiencies ranged from 1.5 log (96.4%) to 2.1 log (99.2%). The 16-mesh/10% sawdust had the greatest mean reduction of 2.1-log (99.2%), though there was no statistically significant difference in removal efficiency. Based on our findings, physical filtration and silver nanoparticle disinfection likely contribute to treatment of C. parvum for silver impregnated ceramic water filters, although the contribution of physical filtration is likely greater than silver disinfection.

  19. Water disinfection with ozone, copper and silver ions, and temperature increase to control Legionella: seven years of experience in a university teaching hospital.

    Science.gov (United States)

    Blanc, D S; Carrara, Ph; Zanetti, G; Francioli, P

    2005-05-01

    The efficacy of ozonation, copper-silver ionization and increased temperature in controlling Legionella spp. in the hot water distribution networks of a university hospital was evaluated. Two separate water distribution networks were studied; network 1 which supplies the surgical intensive care units, and network 2 which supplies the medical intensive care units and the emergency room. Network 1 has been disinfected by ozonation since 1995, and network 2 has been disinfected by ionisation since 1999. The hot water temperature was increased from 50 to 65 degrees C in 1998 and 2000 in networks 1 and 2, respectively. Water samples and swabs of the water outlets were cultured for Legionella spp. between four and six times each year, providing data before and after implementation of the disinfection procedures. There was no significant difference in the proportion of samples positive for Legionella spp. after ozonation in network 1 or after ionization in network 2. In both networks, there was a significant reduction in legionella isolates after increasing the hot water temperature to 65 degrees C. Maintaining the hot water temperature above 50 degrees C throughout both networks proved to be the most effective control measure in our hospital.

  20. Disinfection by-product formation following chlorination of drinking water: artificial neural network models and changes in speciation with treatment.

    Science.gov (United States)

    Kulkarni, Pranav; Chellam, Shankararaman

    2010-09-01

    Artificial neural network (ANN) models were developed to predict disinfection by-product (DBP) formation during municipal drinking water treatment using the Information Collection Rule Treatment Studies database complied by the United States Environmental Protection Agency. The formation of trihalomethanes (THMs), haloacetic acids (HAAs), and total organic halide (TOX) upon chlorination of untreated water, and after conventional treatment, granular activated carbon treatment, and nanofiltration were quantified using ANNs. Highly accurate predictions of DBP concentrations were possible using physically meaningful water quality parameters as ANN inputs including dissolved organic carbon (DOC) concentration, ultraviolet absorbance at 254nm and one cm path length (UV(254)), bromide ion concentration (Br(-)), chlorine dose, chlorination pH, contact time, and reaction temperature. This highlights the ability of ANNs to closely capture the highly complex and non-linear relationships underlying DBP formation. Accurate simulations suggest the potential use of ANNs for process control and optimization, comparison of treatment alternatives for DBP control prior to piloting, and even to reduce the number of experiments to evaluate water quality variations when operating conditions are changed. Changes in THM and HAA speciation and bromine substitution patterns following treatment are also discussed. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Disinfection Byproducts in Drinking Water and Evaluation of Potential Health Risks of Long-Term Exposure in Nigeria.

    Science.gov (United States)

    Benson, Nsikak U; Akintokun, Oyeronke A; Adedapo, Adebusayo E

    2017-01-01

    Levels of trihalomethanes (THMs) in drinking water from water treatment plants (WTPs) in Nigeria were studied using a gas chromatograph (GC Agilent 7890A with autosampler Agilent 7683B) equipped with electron capture detector (ECD). The mean concentrations of the trihalomethanes ranged from zero in raw water samples to 950 μg/L in treated water samples. Average concentration values of THMs in primary and secondary disinfection samples exceeded the standard maximum contaminant levels. Results for the average THMs concentrations followed the order TCM > BDCM > DBCM > TBM. EPA-developed models were adopted for the estimation of chronic daily intakes (CDI) and excess cancer incidence through ingestion pathway. Higher average intake was observed in adults (4.52 × 10-2 mg/kg-day), while the ingestion in children (3.99 × 10-2 mg/kg-day) showed comparable values. The total lifetime cancer incidence rate was relatively higher in adults than children with median values 244 and 199 times the negligible risk level.

  2. Disinfection Byproducts in Drinking Water and Evaluation of Potential Health Risks of Long-Term Exposure in Nigeria

    Directory of Open Access Journals (Sweden)

    Nsikak U. Benson

    2017-01-01

    Full Text Available Levels of trihalomethanes (THMs in drinking water from water treatment plants (WTPs in Nigeria were studied using a gas chromatograph (GC Agilent 7890A with autosampler Agilent 7683B equipped with electron capture detector (ECD. The mean concentrations of the trihalomethanes ranged from zero in raw water samples to 950 μg/L in treated water samples. Average concentration values of THMs in primary and secondary disinfection samples exceeded the standard maximum contaminant levels. Results for the average THMs concentrations followed the order TCM > BDCM > DBCM > TBM. EPA-developed models were adopted for the estimation of chronic daily intakes (CDI and excess cancer incidence through ingestion pathway. Higher average intake was observed in adults (4.52×10-2 mg/kg-day, while the ingestion in children (3.99×10-2 mg/kg-day showed comparable values. The total lifetime cancer incidence rate was relatively higher in adults than children with median values 244 and 199 times the negligible risk level.

  3. Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

    OpenAIRE

    Harding, Alexander S.; Schwab, Kellogg J.

    2012-01-01

    We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Sl...

  4. Solar disinfection of drinking water (SODIS): an investigation of the effect of UV-A dose on inactivation efficiency.

    Science.gov (United States)

    Ubomba-Jaswa, Eunice; Navntoft, Christian; Polo-López, M Inmaculada; Fernandez-Ibáñez, Pilar; McGuigan, Kevin G

    2009-05-01

    The effect of solar UV-A irradiance and solar UV-A dose on the inactivation of Escherichia coli K-12 using solar disinfection (SODIS) was studied. E. coli K-12 was seeded in natural well-water contained in borosilicate glass tubes and exposed to sunlight at different irradiances and doses of solar UV radiation. In addition, E. coli K-12 was also inoculated into poly(ethylene) terephthalate (PET) bottles and in a continuous flow system (10 L min(-1)) to determine the effect of an interrupted and uninterrupted solar dose on inactivation. Results showed that inactivation from approximately 10(6) CFU mL(-1) to below the detection level (4 CFU/mL) for E. coli K-12, is a function of the total uninterrupted dose delivered to the bacteria and that the minimum dose should be >108 kJ m(-2) for the conditions described (spectral range of 0.295-0.385 microm). For complete inactivation to below the limit of detection, this dose needs to be received regardless of the incident solar UV intensity and needs to be delivered in a continuous and uninterrupted manner. This is illustrated by a continuous flow system in which bacteria were not fully inactivated (residual viable concentration approximately 10(2) CFU/mL) even after 5 h of exposure to strong sunlight and a cumulative dose of >108 kJ m(-2). This has serious implications for attempts to scale-up solar disinfection through the use of re-circulatory continuous flow reactors.

  5. Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source.

    Science.gov (United States)

    Pressman, Jonathan G; McCurry, Daniel L; Parvez, Shahid; Rice, Glenn E; Teuschler, Linda K; Miltner, Richard J; Speth, Thomas F

    2012-10-15

    Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation. Published by Elsevier Ltd.

  6. Comparison of the Efficacies of Disinfectants To Control Microbial Contamination in Dental Unit Water Systems in General Dental Practices across the European Union

    Science.gov (United States)

    Schel, A. J.; Marsh, P. D.; Bradshaw, D. J.; Finney, M.; Fulford, M. R.; Frandsen, E.; Østergaard, E.; ten Cate, J. M.; Moorer, W. R.; Mavridou, A.; Kamma, J. J.; Mandilara, G.; Stösser, L.; Kneist, S.; Araujo, R.; Contreras, N.; Goroncy-Bermes, P.; O'Mullane, D.; Burke, F.; O'Reilly, P.; Hourigan, G.; O'Sullivan, M.; Holman, R.; Walker, J. T.

    2006-01-01

    Water delivered by dental unit water systems (DUWS) in general dental practices can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWS provide a reservoir for microorganisms and should be controlled. This study compared disinfection products for their ability to meet the American Dental Association's guideline of <200 CFU · ml−1 for DUWS water. Alpron, BioBlue, Dentosept, Oxygenal, Sanosil, Sterilex Ultra, and Ster4Spray were tested in DUWS (n = 134) in Denmark, Germany, Greece, Ireland, The Netherlands, Spain, and the United Kingdom. Weekly water samples were tested for total viable counts (TVCs) on yeast extract agar, and, where possible, the effects of products on established biofilm (TVCs) were measured. A 4- to 5-week baseline measurement period was followed by 6 to 8 weeks of disinfection (intermittent or continuous product application). DUWS water TVCs before disinfection ranged from 0 to 5.41 log CFU · ml−1. Disinfectants achieved reductions in the median water TVC ranging from 0.69 (Ster4Spray) to 3.11 (Dentosept) log CFU · ml−1, although occasional high values (up to 4.88 log CFU · ml−1) occurred with all products. Before treatment, 64% of all baseline samples exceeded American Dental Association guidelines, compared to only 17% following commencement of treatment; where tested, biofilm TVCs were reduced to below detectable levels. The antimicrobial efficacies of products varied (e.g., 91% of water samples from DUWS treated with Dentosept or Oxygenal met American Dental Association guidelines, compared to 60% of those treated with Ster4Spray). Overall, the continuously applied products performed better than those applied intermittently. The most effective products were Dentosept and Oxygenal, although Dentosept gave the most consistent and sustained antimicrobial effect over time. PMID:16461690

  7. Evaluation of Drinking Water Disinfectant Byproducts Compliance Data as an Indirect Measure for Short-Term Exposure in Humans.

    Science.gov (United States)

    Parvez, Shahid; Frost, Kali; Sundararajan, Madhura

    2017-05-20

    In the absence of shorter term disinfectant byproducts (DBPs) data on regulated Trihalomethanes (THMs) and Haloacetic acids (HAAs), epidemiologists and risk assessors have used long-term annual compliance (LRAA) or quarterly (QA) data to evaluate the association between DBP exposure and adverse birth outcomes, which resulted in inconclusive findings. Therefore, we evaluated the reliability of using long-term LRAA and QA data as an indirect measure for short-term exposure. Short-term residential tap water samples were collected in peak DBP months (May-August) in a community water system with five separate treatment stations and were sourced from surface or groundwater. Samples were analyzed for THMs and HAAs per the EPA (U.S. Environmental Protection Agency) standard methods (524.2 and 552.2). The measured levels of total THMs and HAAs were compared temporally and spatially with LRAA and QA data, which showed significant differences (p regulatory permissible limits: 27% had excessive THMs and 35% had excessive HAAs. Trichloromethane, trichloroacetic acid, and dichloroacetic acid were the major drivers of variability. This study suggests that LRAA and QA data are not good proxies of short-term exposure. Further investigation is needed to determine if other drinking water systems show consistent findings for improved regulation.

  8. The Effect of Different Boiling and Filtering Devices on the Concentration of Disinfection By-Products in Tap Water

    Directory of Open Access Journals (Sweden)

    Glòria Carrasco-Turigas

    2013-01-01

    Full Text Available Disinfection by-products (DBPs are ubiquitous contaminants in tap drinking water with the potential to produce adverse health effects. Filtering and boiling tap water can lead to changes in the DBP concentrations and modify the exposure through ingestion. Changes in the concentration of 4 individual trihalomethanes (THM4 (chloroform (TCM, bromodichloromethane (BDCM, dibromochloromethane (DBCM, and bromoform (TBM, MX, and bromate were tested when boiling and filtering high bromine-containing tap water from Barcelona. For filtering, we used a pitcher-type filter and a household reverse osmosis filter; for boiling, an electric kettle, a saucepan, and a microwave were used. Samples were taken before and after each treatment to determine the change in the DBP concentration. pH, conductivity, and free/total chlorine were also measured. A large decrease of THM4 (from 48% to 97% and MX concentrations was observed for all experiments. Bromine-containing trihalomethanes were mostly eliminated when filtering while chloroform when boiling. There was a large decrease in the concentration of bromate with reverse osmosis, but there was a little effect in the other experiments. These findings suggest that the exposure to THM4 and MX through ingestion is reduced when using these household appliances, while the decrease of bromate is device dependent. This needs to be considered in the exposure assessment of the epidemiological studies.

  9. The effect of different boiling and filtering devices on the concentration of disinfection by-products in tap water.

    Science.gov (United States)

    Carrasco-Turigas, Glòria; Villanueva, Cristina M; Goñi, Fernando; Rantakokko, Panu; Nieuwenhuijsen, Mark J

    2013-01-01

    Disinfection by-products (DBPs) are ubiquitous contaminants in tap drinking water with the potential to produce adverse health effects. Filtering and boiling tap water can lead to changes in the DBP concentrations and modify the exposure through ingestion. Changes in the concentration of 4 individual trihalomethanes (THM4) (chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)), MX, and bromate were tested when boiling and filtering high bromine-containing tap water from Barcelona. For filtering, we used a pitcher-type filter and a household reverse osmosis filter; for boiling, an electric kettle, a saucepan, and a microwave were used. Samples were taken before and after each treatment to determine the change in the DBP concentration. pH, conductivity, and free/total chlorine were also measured. A large decrease of THM4 (from 48% to 97%) and MX concentrations was observed for all experiments. Bromine-containing trihalomethanes were mostly eliminated when filtering while chloroform when boiling. There was a large decrease in the concentration of bromate with reverse osmosis, but there was a little effect in the other experiments. These findings suggest that the exposure to THM4 and MX through ingestion is reduced when using these household appliances, while the decrease of bromate is device dependent. This needs to be considered in the exposure assessment of the epidemiological studies.

  10. Health impacts of long-term exposure to disinfection by-products in drinking water in Europe: HIWATE.

    Science.gov (United States)

    Nieuwenhuijsen, Mark J; Smith, Rachel; Golfinopoulos, Spyros; Best, Nicky; Bennett, James; Aggazzotti, Gabriella; Righi, Elena; Fantuzzi, Guglielmina; Bucchini, Luca; Cordier, Sylvaine; Villanueva, Cristina M; Moreno, Victor; La Vecchia, Carlo; Bosetti, Cristina; Vartiainen, Terttu; Rautiu, Radu; Toledano, Mireille; Iszatt, Nina; Grazuleviciene, Regina; Kogevinas, Manolis

    2009-06-01

    There appears to be very good epidemiological evidence for a relationship between chlorination by-products, as measured by trihalomethanes (THMs), in drinking water and bladder cancer, but the evidence for other cancers, including colorectal cancer appears to be inconclusive and inconsistent. There appears to be some evidence for a relationship between chlorination by-products, as measured by THMs, and small for gestational age (SGA)/intrauterine growth retardation (IUGR) and preterm delivery, but evidence for other outcomes such as low birth weight (LBW), stillbirth, congenital anomalies and semen quality appears to be inconclusive and inconsistent.The overall aim of the HIWATE study is to investigate potential human health risks (e.g. bladder and colorectal cancer, premature births, SGA, semen quality, stillbirth, congenital anomalies) associated with long-term exposure to low levels of disinfectants (such as chlorine) and DBPs occurring in water for human consumption and use in the food industry. The study will comprise risk-benefit analyses including quantitative assessments of risk associated with microbial contamination of drinking water versus chemical risk and will compare alternative treatment options. The outcome will be improved risk assessment and better information for risk management. The work is divided into different topics (exposure assessment, epidemiology, risk assessment and management) and studies.

  11. THE TOXICOLOGY OF COMPLEX MIXTURES OF DISINFECTION BY-PRODUCTS

    Science.gov (United States)

    Chemical disinfection of water is a major public health advance that has decreased dramatically water-borne disease. Chemical disinfectants react with naturally occurring organic and inorganic matter in water to produce a wide variety of disinfection byproducts (DBPs). DBP num...

  12. Solar water disinfection (SODIS): Impact on hepatitis A virus and on a human Norovirus surrogate under natural solar conditions.

    Science.gov (United States)

    Polo, David; García-Fernández, Irene; Fernández-Ibáñez, Pilar; Romalde, Jesús L

    2015-03-01

    This study evaluates the effectiveness of solar water disinfection (SODIS) in the reduction and inactivation of hepatitis A virus (HAV) and of the human Norovirus surrogate, murine Norovirus (MNV-1), under natural solar conditions. Experiments were performed in 330 ml polyethylene terephthalate (PET) bottles containing HAV or MNV-1 contaminated waters (10(3) PFU/ml) that were exposed to natural sunlight for 2 to 8 h. Parallel experiments under controlled temperature and/or in darkness conditions were also included. Samples were concentrated by electropositive charged filters and analysed by RT-real time PCR (RT-qPCR) and infectivity assays. Temperature reached in bottles throughout the exposure period ranged from 22 to 40ºC. After 8 h of solar exposure (cumulative UV dose of ~828 kJ/m2 and UV irradiance of ~20 kJ/l), the results showed significant (PSODIS conditions induced a loss of infectivity between 33.4% and 83.4% after 4 to 8 h in HAV trials, and between 33.4% and 66.7% after 6 h to 8 h in MNV-1 trials. The results obtained indicated a greater importance of sunlight radiation over the temperature as the main factor for viral reduction. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  13. A novel gravity-driven nanofibrous membrane for point-of-use water disinfection: polydopamine-induced in situ silver incorporation.

    Science.gov (United States)

    Wang, Jianqiang; Wu, Yichao; Yang, Zhe; Guo, Hao; Cao, Bin; Tang, Chuyang Y

    2017-05-24

    We report a facile method for preparing silver-loaded membranes for point-of-use disinfection and disaster relief applications. A bio-inspired material, polydopamine, was coated onto a highly porous nanofibrous polyacrylonitrile substrate. We then take advantage of the redox properties of polydopamine to form silver nanoparticles in situ. These nanoparticles were uniformly distributed on the surface of nanofibers with no apparent agglomeration at a silver loading up to 4.36 wt.% (cPAN-Ag1.5). The silver-incorporated membrane cPAN-Ag1.5 achieved a high pure water flux of 130 Lm-2 h-1 at 10-cm water head, demonstrating the feasibility of energy-efficient gravity-driven filtration and eliminating the need for electrical power. The strong anti-bacterial activity and high physical rejection of the membrane led to an excellent disinfection power, with no viable bacterial cells detected in its permeate water. The membrane exhibited >7 log reduction for E. coli and >6 log reduction for B. subtilis. The strategy reported here provides an efficient and green route to synthesize point-of-use membranes. Combining their excellent permeability and disinfection effectiveness, these membranes offer an ideal solution to water supply in disaster-affected areas.

  14. Analysis and occurrence of odorous disinfection by-products from chlorination of amino acids in three different drinking water treatment plants and corresponding distribution networks.

    Science.gov (United States)

    Brosillon, Stephan; Lemasle, Marguerite; Renault, Emilie; Tozza, Dominique; Heim, Veronique; Laplanche, Alain

    2009-11-01

    Previous studies have established that odorous and stable chloraldimines are formed during amino acid chlorination in drinking water treatment. In order to identify at low level (10(-8) M) the presence of these odorous disinfection by-products in drinking water matrixes an analytical method was developed by using head space apparatus (HS) combined with a sorbent trap system linked to a GC with a mass spectrometer detector (HS/Trap/GC/MS). The analyses were carried out in three different drinking water supplies from the Paris area, during the four seasons. Free amino acids were monitored at the inlet of the plant. The odorous disinfection by-products were analyzed at the outlet of each drinking water treatment plant and the different distribution networks were connected to the corresponding plant. The results confirmed that the odorous chloraldimines are produced during chlorination of free amino acids in three different matrixes in different seasons throughout the year (N-chloroisobutaldimine; N-chloromethyl-2-butaldimine; N-chloromethyl-3-butaldimine (6-10 nM). The analytical method (HS/Trap/GC/MS) used to monitor odorous disinfection by-products appeared to be adapted for the detection of these by-products at nM level.

  15. Biofilm Composition and Threshold Concentration for Growth of Legionella pneumophila on Surfaces Exposed to Flowing Warm Tap Water without Disinfectant.

    Science.gov (United States)

    van der Kooij, Dick; Bakker, Geo L; Italiaander, Ronald; Veenendaal, Harm R; Wullings, Bart A

    2017-03-01

    Legionella pneumophila in potable water installations poses a potential health risk, but quantitative information about its replication in biofilms in relation to water quality is scarce. Therefore, biofilm formation on the surfaces of glass and chlorinated polyvinyl chloride (CPVC) in contact with tap water at 34 to 39°C was investigated under controlled hydraulic conditions in a model system inoculated with biofilm-grown L. pneumophila The biofilm on glass (average steady-state concentration, 23 ± 9 pg ATP cm-2) exposed to treated aerobic groundwater (0.3 mg C liter-1; 1 μg assimilable organic carbon [AOC] liter-1) did not support growth of the organism, which also disappeared from the biofilm on CPVC (49 ± 9 pg ATP cm-2) after initial growth. L. pneumophila attained a level of 4.3 log CFU cm-2 in the biofilms on glass (1,055 ± 225 pg ATP cm-2) and CPVC (2,755 ± 460 pg ATP cm-2) exposed to treated anaerobic groundwater (7.9 mg C liter-1; 10 μg AOC liter-1). An elevated biofilm concentration and growth of L. pneumophila were also observed with tap water from the laboratory. The Betaproteobacteria Piscinibacter and Methyloversatilis and amoeba-resisting Alphaproteobacteria predominated in the clones and isolates retrieved from the biofilms. In the biofilms, the Legionella colony count correlated significantly with the total cell count (TCC), heterotrophic plate count, ATP concentration, and presence of Vermamoeba vermiformis This amoeba was rarely detected at biofilm concentrations of water-associated disease outbreaks reported in the United States. The organism proliferates in biofilms on surfaces exposed to warm water in engineered freshwater installations. An investigation with a test system supplied with different types of warm drinking water without disinfectant under controlled hydraulic conditions showed that treated aerobic groundwater (0.3 mg liter-1 of organic carbon) induced a low biofilm concentration that supported no or very limited growth of L

  16. Solar disinfection of drinking water in the prevention of dysentery in South African children under 5 years: the role of participant motivation

    CSIR Research Space (South Africa)

    Du Preez, M

    2010-11-01

    Full Text Available , Mcguigan, K 2 and Conroy, R.M 3 1Natural Resources and the Environment, CSIR,P.O. Box 395, Pretoria, South Africa 2Department of Physiology & Medical Physics Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland 3...Division of Population Health Sciences, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland Abstract Solar disinfection (SODIS) effectively improves the microbial quality of drinking water for preventing diarrhea...

  17. A School-based Trial Protocol in Community Promotion of Solar Water Disinfection (SODIS): A Case Study of Ndagwe Sub County, Central Uganda

    OpenAIRE

    Asiimwe, Jacent Kamuntu

    2013-01-01

    Improvement in microbial quality of drinking water by solar disinfection (SODIS) results in reduced diarrheal episodes among users. In this study, a randomized cluster stepped wedge study design was used to assess the use of primary school pupils as community promoters of SODIS technology in Ndagwe sub county, central Uganda. The intervention (SODIS) was introduced to pupils in the different school clusters at different time points throughout the year. Pupils were to only drink SODIS treated ...

  18. New disinfection and sterilization methods.

    OpenAIRE

    Rutala, W A; Weber, D.J.

    2001-01-01

    New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxid...

  19. Zeolites modified with silver for the development of a water disinfection system; Zeolitas modificadas con plata para el desarrollo de un sistema de desinfeccion de agua

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio V, S.

    2013-07-01

    In spite of great strides that have been taken in sanitation technologies, there still exist health problems due to microbiological contamination by water. The waterborne diseases have not been completely eradicated and are a big problem of economic interest and health. Moreover, the microbicidal properties of silver have been used for a long time. The use of silver as a disinfectant has many advantages; for example it inhibits a wide spectrum of microorganisms, it has oligo dynamic properties and owing its mechanisms of cell inactivation, it also does not allow the emergence of new resistant strains. In the present research, the kinetics of water disinfection with silver has been investigated, to develop small system for water disinfection, based in silver modified Mexican clinoptilolite. The chemical species of silver play a significant role in the disinfection processes. For this reason, in this work, were both the Ag{sup +} and nanoparticles of Ag{sup ο} considered. The synthesis of nanoparticles of Ag{sup ο} woes performed by thermal and chemical reduction. It was found that the chemical reduction of Ag{sup +} to Ag{sup ο} was more efficient because it presented more defined nano structures and better distribution than those of thermal reduction. Clinoptilolite of Taxco (Guerrero) was chosen to exchange the native ions from the clinoptilolite by Ag{sup +} from the aqueous medium, or to deposit the nanoparticles of Ag{sup ο} on this surface. These silver modified zeolitic materials were characterized by scanning electron microscopy (Sem), elemental analyses (EDS), X-ray diffraction (XRD) and neutron activation analysis (NAA). The results showed that the crystallographic structure of the clinoptilolite did not change during thermal and chemical reduction treatments of Ag{sup +} to obtain the nanoparticles of Ag{sup ο}. The bactericide activity of the silver modified zeolitic materials (with Ag{sup +} or nanoparticles of Ag{sup ο}) was evaluated on

  20. Spatial and seasonal variability of tap water disinfection by-products within distribution pipe networks.

    Science.gov (United States)

    Charisiadis, Pantelis; Andra, Syam S; Makris, Konstantinos C; Christophi, Costas A; Skarlatos, Dimitrios; Vamvakousis, Vasilis; Kargaki, Sophia; Stephanou, Euripides G

    2015-02-15

    Gradually-changing shocks associated with potable water quality deficiencies are anticipated for urban drinking-water distribution systems (UDWDS). The impact of structural UDWDS features such as, the number of pipe leaking incidences on the formation of water trihalomethanes (THM) at the geocoded household level has never been studied before. The objectives were to: (i) characterize the distribution of water THM concentrations in households from two district-metered areas (DMAs) with contrasting UDWDS characteristics sampled in two seasons (summer and winter), and (ii) assess the within- and between-household, spatial variability of water THM accounting for UDWDS characteristics (household distance from chlorination tank and service pipe leaking incidences). A total of 383 tap water samples were collected from 193 households located in two DMAs within the UDWDS of Nicosia city, Cyprus, and analyzed for the four THM species. The higher intraclass correlation coefficient (ICC) values for water tribromomethane (TBM) (0.75) followed by trichloromethane (0.42) suggested that the two DMAs differed with respect to these analytes. On the other hand, the low ICC values for total THM levels between the two DMAs suggested a large variance between households. The effect of households nested under each DMA remained significant (pnetwork characteristics. Our results could find use by water utilities in overcoming techno-economic difficulties associated with the large spatiotemporal variability of THM, while accounting for the influence of UDWDS features at points of water use. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Silver Nanoparticles (AgNP impregnated filters in drinking water disinfection

    Directory of Open Access Journals (Sweden)

    Rus Alexandru

    2017-01-01

    Full Text Available This paper describes how simple portable devices could eliminate water pathogens by using Silver Nanoparticles, based on their antimicrobial properties. Recent studies indicated that silver nanoparticles can achieve up to 100% antibacterial activity removal. Results are showing that Silver Nanoparticles retention in the filter structure, E. coli bacteria removal, water quality and water flow rate must be evaluated as main efficiency indicators of the designed filters, in order to obtain the optimal filter. To apply the antimicrobial property of Silver in drinking-water treatment, a filter is produced using Additive Manufacturing techniques and coated with different concentrations of silver solutions.

  2. Investigation of bromide ion effects on disinfection by-products formation and speciation in an Istanbul water supply.

    Science.gov (United States)

    Uyak, Vedat; Toroz, Ismail

    2007-10-22

    Recent epidemiological studies reported that brominated DBPs may be more carcinogenic than their chlorinated analogs. Thus, this research was designed to investigate the role of bromide ion in the formation and speciation of disinfection by-products (DBPs) during chlorination of Buyukcekmece Lake Water (BLW) in Istanbul. Chlorination of BLW samples was carried out at pH 7.0 with 5 and 12 mg/l chlorine dosages. For each chlorine dosage, six bromide concentrations ranging from 0.05 to 4.0mg/l were added to form a 2 x 6 experimental matrix. In general, increasing bromide concentration gradually shifted trihalomethanes (THMs) and haloacetic acids (HAAs) speciation from chlorinated species to the mixed bromochloro species during chlorination. The halogen substitution ability of HOBr and HOCl during the formation of THMs and HAAs can be estimated through the use of probability theory. It was concluded that, in both halogen substitution for THM and dihalogenated HAA formation, HOBr was found to be 20 times more reactive than HOCl.

  3. Uji Efektivitas Jeruk Nipis (Citrus aurantifolia dalam Mempercepat Laju Disinfeksi Bakteri Escheria Coli pada Proses Solar Water Disinfection

    Directory of Open Access Journals (Sweden)

    Saprian Saprian

    2015-08-01

    Full Text Available Solar Water Disinfection (SODIS memerlukan waktu rata-rata berkisar antara 5-6 jam untuk dapat membunuh bakteri 3-4 Log pada air berkapasitas maksimal 2 liter atau 1 jam dengan suhu di atas 50°C. Penelitian terbaru menunjukkan bahwa dengan mengkombinasikan SODIS dengan psoralens, zat aktif seperti yang terdapat pada jeruk Lemon (Citrus Limon dapat menginaktivasi bakteri hingga 5,6 Log reduksi dalam rentang waktu 30 menit pada suhu 29°C. Mengingat faktor ketersediaan dan harga jeruk lemon di Indonesia maka pada penelitian ini dilakukan pengamatan dengan menggunakan jeruk nipis (Citrus aurantifolia. Penelitian ini dilakukan untuk mengetahui seberapa besar potensi jeruk nipis untuk dipergunakan dalam mempercepat laju disinfeksi pada proses SODIS. Adapun faktor-faktor yang akan dipelajari terkait dengan hubungan antara variasi dosis jeruk nipis, perubahan pH dan suhu air terhadap efisiensi inaktivasi bakteri yang mampu dihasilkan. Variasi jeruk nipis yang digunakan adalah 0%, 2%, 4% dan 6% dengan variasi waktu 0 menit, 30 menit, 60 menit dan 120 menit. Hasil penelitian menunjukkan bahwa perlakuan SODIS dengan menggunakan jeruk nipis mampu menginaktivasi E. coli sebesar 5.4 Log dengan waktu 1 jam pada suhu 32°C. Hal ini menunjukkan bahwa Jeruk nipis berpotensi untuk digunakan dalam mempercepat laju disinfeksi E. coli pada air minum. Kata Kunci : SODIS, E.coli, Psoralens, Jeruk Nipis

  4. FATE OF REVERSE OSMOSIS (RO) MEMBRANES DURING OXIDATION BY DISINFECTANTS USED IN WATER TREATMENT: IMPACT ON MEMBRANE STRUCTURE AND PERFORMANCES

    KAUST Repository

    Maugin, Thomas

    2013-12-01

    Providing pretreatment prior RO filtration is essential to avoid biofouling and subsequent loss of membrane performances. Chlorine is known to degrade polymeric membrane, improving or reducing membrane efficiency depending on oxidation conditions. This study aimed to assess the impact of alternative disinfectant, NH2Cl, as well as secondary oxidants formed during chloramination of seawater, e.g. HOBr, HOI, or used in water treatment e.g. ClO2, O3, on membrane structure and performances. Permeability, total and specific rejection (Cl-, SO4 2-, Br-, Boron), FTIR profile, elemental composition were analyzed. Results showed that each oxidant seems to react differently with the membrane. HOCl, HOBr, ClO2 and O3 improved membrane permeability but decreased rejection in different extent. In comparison, chloramines resulted in identical trends but oxidized membrane very slowly. On the contrary, iodine improved membrane rejection e.g. boron, but decreased permeability. Reaction conducted with chlorine, bromine, iodine and chloramines resulted in the incorporation of halogen in the membrane structure. All oxidant except iodine were able to break amide bonds of the membrane structure in our condition. In addition, chloramine seemed to react with membrane differently, involving a potential addition of nitrogen. Chloramination of seawater amplified membrane performances evolutions due to generation of bromochloramine. Moreover, chloramines reacted both with NOM and membrane during oxidation in natural seawater, leading to additional rejection drop.

  5. Drinking-water disinfection by-products and semen quality: a cross-sectional study in China.

    Science.gov (United States)

    Zeng, Qiang; Wang, Yi-Xin; Xie, Shao-Hua; Xu, Liang; Chen, Yong-Zhe; Li, Min; Yue, Jing; Li, Yu-Feng; Liu, Ai-Lin; Lu, Wen-Qing

    2014-07-01

    Exposure to disinfection by-products (DBPs) has been demonstrated to impair male reproductive health in animals, but human evidence is limited and inconsistent. We examined the association between exposure to drinking-water DBPs and semen quality in a Chinese population. We recruited 2,009 men seeking semen analysis from the Reproductive Center of Tongji Hospital in Wuhan, China, between April 2011 and May 2012. Each man provided a semen sample and a urine sample. Semen samples were analyzed for sperm concentration, sperm motility, and sperm count. As a biomarker of exposure to drinking-water DBPs, trichloroacetic acid (TCAA) was measured in the urine samples. The mean (median) urinary TCAA concentration was 9.58 (7.97) μg/L (interquartile range, 6.01-10.96 μg/L). Compared with men with urine TCAA in the lowest quartile, increased adjusted odds ratios (ORs) were estimated for below-reference sperm concentration in men with TCAA in the second and fourth quartiles (OR = 1.79; 95% CI: 1.19, 2.69 and OR = 1.51; 95% CI: 0.98, 2.31, respectively), for below-reference sperm motility in men with TCAA in the second and third quartiles (OR = 1.46; 95% CI: 1.12, 1.90 and OR = 1.30; 95% CI: 1.00, 1.70, respectively), and for below-reference sperm count in men with TCAA in the second quartile (OR 1.62; 95% CI: 1.04, 2.55). Nonmonotonic associations with TCAA quartiles were also estimated for semen parameters modeled as continuous outcomes, although significant negative associations were estimated for all quartiles above the reference level for sperm motility. Our findings suggest that exposure to drinking-water DBPs may contribute to decreased semen quality in humans.

  6. A novel combined solar pasteurizer/TiO2 continuous-flow reactor for decontamination and disinfection of drinking water.

    Science.gov (United States)

    Monteagudo, José María; Durán, Antonio; Martín, Israel San; Acevedo, Alba María

    2017-02-01

    A new combined solar plant including an annular continuous-flow compound parabolic collector (CPC) reactor and a pasteurization system was designed, built, and tested for simultaneous drinking water disinfection and chemical decontamination. The plant did not use pumps and had no electricity costs. First, water continuously flowed through the CPC reactor and then entered the pasteurizer. The temperature and water flow from the plant effluent were controlled by a thermostatic valve located at the pasteurizer outlet that opened at 80 °C. The pasteurization process was simulated by studying the effect of heat treatment on the death kinetic parameters (D and z values) of Escherichia coli K12 (CECT 4624). 99.1% bacteria photo-inactivation was reached in the TiO2-CPC system (0.60 mg cm-2 TiO2), and chemical decontamination in terms of antipyrine degradation increased with increasing residence time in the TiO2-CPC system, reaching 70% degradation. The generation of hydroxyl radicals (between 100 and 400 nmol L-1) was a key factor in the CPC system efficiency. Total thermal bacteria inactivation was attained after pasteurization in all cases. Chemical degradation and bacterial photo-inactivation in the TiO2-CPC system were improved with the addition of 150 mg L-1 of H2O2, which generated approximately 2000-2300 nmol L-1 of HO● radicals. Finally, chemical degradation and bacterial photo-inactivation kinetic modelling in the annular CPC photoreactor were evaluated. The effect of the superficial liquid velocity on the overall rate constant was also studied. Both antipyrine degradation and E. coli photo-inactivation were found to be controlled by the catalyst surface reaction rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Disinfection by-product formation of UV treated swimming pool water

    DEFF Research Database (Denmark)

    Spiliotopoulou, Aikaterini; Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

    2015-01-01

    Water samples from 3 indoor swimming pool facilities were tested to evaluate UV-induced effects on swimming pool water chemistry. Concentration change of several DBPs was investigated in experiments including medium pressure UV treatment with and without chlorine and post-UV chlorination. Post-UV...

  8. Microbiological effectiveness and cost of disinfecting water by boiling in semi-urban India.

    Science.gov (United States)

    Clasen, Thomas; McLaughlin, Catherine; Nayaar, Neeru; Boisson, Sophie; Gupta, Romesh; Desai, Dolly; Shah, Nimish

    2008-09-01

    Despite shortcomings, boiling is the most common means of treating water at home and the benchmark against which emerging point-of-use water treatment approaches are measured. In a 5-month study, we assessed the microbiological effectiveness and cost of the practice among 218 self-reported boilers relying on unprotected water supplies. Boiling was associated with a 99% reduction in geometric mean fecal coliforms (FCs; P water, 59.6% of stored drinking water samples from self-reported boilers met the World Health Organization standard for safe drinking water (0 FC/100 mL), and 5.7% were between 1 and 10 FC/100 mL. Nevertheless, 40.4% of stored drinking water samples were positive for FCs, with 25.1% exceeding 100 FC/100 mL. The estimated monthly fuel cost for boiling was INR 43.8 (US$0.88) for households using liquid petroleum gas and INR 34.7 (US$0.69) for households using wood.

  9. Disinfectant-resistant bacteria in Buenos Aires city hospital wastewater Resistência bacteriana a desinfetantes em efluentes de um hospital em Buenos Aires, Argentina

    Directory of Open Access Journals (Sweden)

    L. Nuñez

    2007-12-01

    Full Text Available Large quantities of disinfectants are used in hospitals, externally on human skin or to eliminate microorganisms from inanimate objects. After use, residual quantities of these products reach the wastewater, exposing the bacteria that survive in hospital wastewaters to a wide range of biocides that could act as a selective pressure for the development of resistance. Increasing attention has been directed recently to the resistance of bacteria to disinfectants. The aim of this paper was to determine the disinfectant bacterial resistance pattern of the microflora released to the urban sewer system by hospital effluents. The characterization of the waste water microflora was performed by determination of the CFU of heterotrophic bacteria, fecal indicator bacteria, Pseudomonas sp. and Staphylococcus sp., in a Buenos Aires hospital effluent. The bacterial resistance to the disinfectants more frequently used in the hospital practice, glutaraldehyde, chlorhexidine and povidone-iodine, was then evaluated. Disinfectant resistant bacterial strains were isolated and typified. Between 10³ and 10(6 chlorexidine resistant bacteria/100 mL were isolated from the samples. Bacteria resistant to other disinfectants ranged between 10³ and 10(4 /100 mL. The bacterial population resistant to desinfectants to was mainly composed by Enterobacteriaceae, Staphylococcus spp, and Bacillus spp, which are highly associated to nosocomial infections. The results obtained show that the hospital effluents are of importance in the bacterial resistance selection process, particularly in the case of disinfectants.Os hospitais utilizam uma grande quantidade de desinfetantes para eliminar microorganismos tanto da pele humana como de superfícies inanimadas. Após sua utilização, esses produtos podem chegar ao esgoto em quantidades residuais. A pressão seletiva exercida pelos antimicrobianos nos efluentes hospitalares propicia a disseminação de linhagens resistentes. Além dos

  10. Seasonal evaluation of the presence of 46 disinfection by-products throughout a drinking water treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Maria; Montesinos, Isabel; Cardador, M.J.; Silva, Manuel; Gallego, Mercedes, E-mail: mercedes.gallego@uco.es

    2015-06-01

    In this work, we studied a total of 46 regulated and non-regulated disinfection by-products (DBPs) including 10 trihalomethanes (THMs), 13 haloacetic acids (HAAs), 6 halonitromethanes (HNMs), 6 haloacetonitriles (HANs) and 11 aldehydes at different points in a drinking water treatment plant (DWTP) and its distribution network. Determining an increased number of compounds and using accurate, sensitive analytical methodologies for new DBPs can be useful to overcome some challenges encountered in the comprehensive assessment of the quality and safety of drinking water. This paper provides a detailed picture of the spatial and seasonal variability of DBP concentrations from raw water to distribution network. Samples were collected on a monthly basis at seven different points in the four seasons of a year to acquire robust data for DBPs and supplementary quality-related water parameters. Only 5 aldehydes and 2 HAAs were found in raw water. Chlorine dioxide caused the formation of 3 new aldehydes (benzaldehyde included), 5 HAAs and chloroform. The concentrations of DBPs present in raw water were up to 6 times higher in the warmer seasons (spring and summer). The sedimentation process further increased their concentrations and caused the formation of three new ones. Sand filtration substantially removed aldehydes and HAAs (15–50%), but increased the levels of THMs, HNMs and HANs by up to 70%. Chloramination raised the levels of 8 aldehydes and 7 HAAs; also, it caused the formation of monoiodoacetic acid, dibromochloromethane, dichloroiodomethane and bromochloroacetonitrile. Therefore, this treatment increases the levels of existing DBPs and leads to the formation of new ones to a greater extent than does chlorine dioxide. Except for 5 aldehydes, the 23 DBPs encountered at the DWTP exit were found at increased concentrations in the warmer seasons (HAAs by about 50% and THMs by 350%). - Highlights: • Occurrence of 46 regulated and non-regulated DBPs through a DWTP was

  11. Physicochemical Quality and Chemical Safety of Chlorine as a Reconditioning Agent and Wash Water Disinfectant for Fresh-Cut Lettuce Washing

    Science.gov (United States)

    Van Haute, Sam; Holvoet, Kevin; Uyttendaele, Mieke

    2013-01-01

    Chlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated with Escherichia coli O157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The model that incorporated chlorine dose and chemical oxygen demand (COD) of the wash water accurately predicted inactivation. Listeria monocytogenes was more resistant to chlorine reconditioning in artificial wash water than Salmonella spp. and Escherichia coli O157. During the washing process with inoculated lettuce (4 log CFU/g), in the absence of chlorine, there was a rapid microbial buildup in the water that accumulated to 5.4 ± 0.4 log CFU/100 ml after 1 h. When maintaining a residual concentration of 1 mg/liter free chlorine, wash water contamination was maintained below 2.7, 2.5, and 2.5 log CFU/100 ml for tap water and artificial process water with COD values of 500 and 1,000 mg O2/liter, respectively. A model was developed to predict water contamination during the dynamic washing process. Only minor amounts of total trihalomethanes were formed in the water during reconditioning. Total trihalomethanes accumulated to larger amounts in the water during the wash water disinfection experiments and reached 124.5 ± 13.4 μg/liter after 1 h of execution of the washing process in water with a COD of 1,000 mg O2/liter. However, no total trihalomethanes were found on the fresh-cut lettuce after rinsing. PMID:23396332

  12. Physicochemical quality and chemical safety of chlorine as a reconditioning agent and wash water disinfectant for fresh-cut lettuce washing.

    Science.gov (United States)

    Van Haute, Sam; Sampers, Imca; Holvoet, Kevin; Uyttendaele, Mieke

    2013-05-01

    Chlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated with Escherichia coli O157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The model that incorporated chlorine dose and chemical oxygen demand (COD) of the wash water accurately predicted inactivation. Listeria monocytogenes was more resistant to chlorine reconditioning in artificial wash water than Salmonella spp. and Escherichia coli O157. During the washing process with inoculated lettuce (4 log CFU/g), in the absence of chlorine, there was a rapid microbial buildup in the water that accumulated to 5.4 ± 0.4 log CFU/100 ml after 1 h. When maintaining a residual concentration of 1 mg/liter free chlorine, wash water contamination was maintained below 2.7, 2.5, and 2.5 log CFU/100 ml for tap water and artificial process water with COD values of 500 and 1,000 mg O2/liter, respectively. A model was developed to predict water contamination during the dynamic washing process. Only minor amounts of total trihalomethanes were formed in the water during reconditioning. Total trihalomethanes accumulated to larger amounts in the water during the wash water disinfection experiments and reached 124.5 ± 13.4 μg/liter after 1 h of execution of the washing process in water with a COD of 1,000 mg O2/liter. However, no total trihalomethanes were found on the fresh-cut lettuce after rinsing.

  13. Risk of stillbirth in the relation to water disinfection by-products: a population-based case-control study in Taiwan.

    Directory of Open Access Journals (Sweden)

    Bing-Fang Hwang

    Full Text Available BACKGROUND: Few epidemiological studies that have assessed the relation between water disinfection by-products (DBPs and the risk of stillbirth provide inconsistent results. The objective was to assess the relation between exposure to water disinfection by-products and the risk of stillbirth. METHODS: We conducted a population-based case-control study of 3,289 cases of stillbirth and a random sample of 32,890 control subjects from 396,049 Taiwanese newborns in 2001-2003 using information from the Birth Registry and Waterworks Registry in Taiwan. We compared the risk of stillbirth in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs representing high (TTHMs 20+ µg/L, medium (TTHMs 10-19 µg/L, low exposure (TTHMs 5-9 µg/L, and 0-4 µg/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and 5 previous studies focusing on stillbirth. FINDINGS: In logistic regression analysis adjusting for gender, maternal age, plurality, conception of season and population density of the municipality where the mother lived during pregnancy, the odds ratio (OR for stillbirth was 1.10 (95% CI 1.00-1.21 for medium exposure and 1.06 (95% 0.96-1.17 for high exposure compared to reference category. In the meta-analysis, the summary odds ratio for stillbirth (1.11, 95% CI: 1.03, 1.19 was consistently elevated. CONCLUSIONS: The present study is consistent with the hypothesis that the risk of stillbirth is related to prenatal exposure to disinfection by-products. This finding on stillbirth is consistent with previous epidemiologic studies, which strengthens the weight of evidence.

  14. Understanding the Impacts and Meaning of Maintaining Detectable Disinfection Residuals in Drinking Water Distribution Systems: Controlling Waterborne Pathogens, Disinfection Byproducts, Organic Chloramines, and Nitrification

    Science.gov (United States)

    : EPA Region 6, in collaboration with the Office of Research and Development and Office of Water (OW) in Cincinnati, Ohio, and the Louisiana Department of Health and Hospitals (LDHH), proposes a drinking water research project to understand how maintaining various drinking water...

  15. Spatial variations in the occurrence of potentially genotoxic disinfection by-products in drinking water distribution systems in China.

    Science.gov (United States)

    Li, Chunmei; Wang, Donghong; Xu, Xiong; Xu, Meijia; Wang, Zijian

    2017-12-01

    We investigated the occurrence of disinfection by-products (DBPs) with genotoxic potential in plant effluent and distribution water samples from four drinking water treatment plants in two Chinese cities using comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry. We tested the samples for 37 DBPs with genotoxic potential, which we had previously identified and prioritized in water under controlled laboratory conditions. Thirty of these DBPs were found in the water samples at detection frequencies of between 10% and 100%, and at concentrations between 3.90 and 1.77 × 10 3  ng/L. Of the DBPs detected, the concentrations of 1,1,1-trichloropropan-2-one were highest, and ranged from 299 to 1.77 × 10 3  ng/L with an average of 796 ng/L. The concentrations of 6-chloro-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine and 2,6-ditert-butylcyclohexa-2,5-diene-1,4-dione were also much higher, and ranged from 107 to 721 ng/L, and from 152 to 504 ng/L, respectively. Concentrations of 1,1,1-trichloropropan-2-one, 2-chloro-1-phenylethanone, 2,2-dichloro-1-phenylethanone and 6-chloro-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine were highest at or near the treatment plants and decreased with increasing distance from the plants. Patterns in the concentrations of benzaldehyde, 2-phenylpropan-2-ol, and 1-methylnaphthalene differed between plants. The levels of DBPs such as 4-ethylbenzaldehyde, (E)-non-2-enal, and 1-phenylethanone were relatively constant within the distribution systems, even at the furthest sampling points (20 km < d < 30 km). A risk assessment showed that there was no risk to human health. It is, however, important to note that, because of limited availability of toxicity data, only five DBPs were evaluated in this study. The risks to health associated with exposure to the target potentially genotoxic DBPs should not be ignored because of their prolonged existence in drinking water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. UV disinfection of indigenous aerobic spores: implications for UV reactor validation in unfiltered waters.

    Science.gov (United States)

    Mamane-Gravetz, Hadas; Linden, Karl G

    2004-07-01

    Conventional validation testing of UV reactors use cultured microorganisms spiked into test water flowing through a reactor. These tests are limited by the microbe titer it is possible to grow, thus limiting the size of the reactor it is possible to validate. The goal of this study was to examine the UV inactivation of indigenous aerobic spores naturally occurring in raw/unfiltered water supplies and to assess their use as an alternative indicator for validation testing of UV reactor performance, specifically for unfiltered water supplies planning large UV reactors. These spores were found in all raw waters tested in concentrations ranging between 20 and 12,000 CFU/100 mL and were very resistant to UV irradiation compared to a range of different microbes in the literature (i.e. adenovirus, MS-2 coliphage, and Cryptosporidium parvum). The inactivation of indigenous natural aerobic spores followed first-order kinetics with an inactivation coefficient ranging between 0.013 and 0.022 cm2/mJ with a high correlation coefficient. It was determined that naturally occurring aerobic spores, well characterized with respect to UV 253.7 nm inactivation, can be a useful tool when validating plant performance, and might also be used as a regular monitor of UV fluence and performance in a water treatment plant.

  17. Environmentally friendly disinfectant: Production, disinfectant action and efficiency

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan I.

    2006-01-01

    Full Text Available Silver is a known disinfectant from ancient times, and it has been widely used for various purposes: for food and water disinfection, curing of wounds and as a universal antibiotic for a wide spectrum of diseases - until the Second World War and the discovery of penicillin. Until recently, it was assumed that silver, being a heavy metal, was toxic for humans and living beings. However, the newest research provides facts that the usage of silver, even for drinking water disinfection, is benign if it is added in small concentrations (in parts per billion. It has been shown in the newer scientific and technical literature that silver in colloidal form is a powerful (secondary disinfectant for drinking water, that it can be effectively used for the disinfection of water containers including swimming pools, installations in food industry, medicine, etc. Particularly, it has been shown that colloidal silver combined with hydrogen peroxide shows synergism having strong bactericidal and antiviral effects. The combination can be successfully used as a disinfectant in agriculture, food production and medicine. The original electrochemical process of production, the mechanism of physical-chemical reactions in that process and the mechanism of the antiseptic affect of the environmentally friendly disinfectant, based on the synergism of colloidal silver and hydrogen peroxide and the activity of electrochemically activated water, is shown. The starting solution was anolyte, obtained in electrochemical activation by water electrolysis of a highly diluted solution of K-tartarate in demineralized water (5.5-1CT4 M. The problem of electrolysis of very dilute aqueous solutions in membrane cells was particularly treated. It was shown that the efficiency of the electrolysis depends on the competition between the two processes: the rates of the processes of hydrogen and oxygen generation at the electrodes and the process of diffusion of hydrogen and hydroxyl ions

  18. Identification of Halohydrins as Potential Disinfection By-Products in Treated Drinking Water

    Directory of Open Access Journals (Sweden)

    Karl J. Jobst

    2011-01-01

    It appears that DBP-A is 3-chloro-2-methylbutan-2-ol and that DBP-B is its bromo analogue. DBP-B has been detected in ozonated waters containing bromide. Our study also shows that these DBPs can be laboratory artefacts, generated by the reaction of residual chlorine in the sample with 2-methyl-2-butene, the stabilizer in the CH2Cl2 used for extraction. This was shown by experiments using CH2Cl2 stabilized with deuterium labelled 2-methyl-2-butene. Quenching any residual chlorine in the drinking water sample with sodium thiosulfate minimizes the formation of these artefacts.

  19. SOLAIR disinfection of coliform bacteria in hand-drawn drinking water

    African Journals Online (AJOL)

    specifically UV-A and UV-B radiation) and oxygen (from atmospheric air) to damage, inactivate and / or kill the coliform bacteria found in contaminated water. It is a natural process (virtually self-purification) with no need to add any potentially hazardous ...

  20. Reduction of disinfection by-products in natural waters using nanofiltration membranes

    OpenAIRE

    Sentana Gadea, Irene; Rodríguez Pastor, Manuel; Sentana Cremades, Eloy; M'Birek, Chafik; Prats Rico, Daniel

    2008-01-01

    Póster presentado en Conference on Membranes in Drinking and Industrial Water Production, Toulouse, 20–24 October 2008. This study was financial supported by the “Generalitat Valenciana GV07/129 ” of the Spanish Government and Project de I+D 2007-2010 CTQ2007-66780 by the Spanish Government.

  1. Solar drinking water disinfection (SODIS to reduce childhood diarrhoea in rural Bolivia: a cluster-randomized, controlled trial.

    Directory of Open Access Journals (Sweden)

    Daniel Mäusezahl

    2009-08-01

    Full Text Available Solar drinking water disinfection (SODIS is a low-cost, point-of-use water purification method that has been disseminated globally. Laboratory studies suggest that SODIS is highly efficacious in inactivating waterborne pathogens. Previous field studies provided limited evidence for its effectiveness in reducing diarrhoea.We conducted a cluster-randomized controlled trial in 22 rural communities in Bolivia to evaluate the effect of SODIS in reducing diarrhoea among children under the age of 5 y. A local nongovernmental organisation conducted a standardised interactive SODIS-promotion campaign in 11 communities targeting households, communities, and primary schools. Mothers completed a daily child health diary for 1 y. Within the intervention arm 225 households (376 children were trained to expose water-filled polyethyleneteraphtalate bottles to sunlight. Eleven communities (200 households, 349 children served as a control. We recorded 166,971 person-days of observation during the trial representing 79.9% and 78.9% of the total possible person-days of child observation in intervention and control arms, respectively. Mean compliance with SODIS was 32.1%. The reported incidence rate of gastrointestinal illness in children in the intervention arm was 3.6 compared to 4.3 episodes/year at risk in the control arm. The relative rate of diarrhoea adjusted for intracluster correlation was 0.81 (95% confidence interval 0.59-1.12. The median length of diarrhoea was 3 d in both groups.Despite an extensive SODIS promotion campaign we found only moderate compliance with the intervention and no strong evidence for a substantive reduction in diarrhoea among children. These results suggest that there is a need for better evidence of how the well-established laboratory efficacy of this home-based water treatment method translates into field effectiveness under various cultural settings and intervention intensities. Further global promotion of SODIS for general use

  2. Solar drinking water disinfection (SODIS) to reduce childhood diarrhoea in rural Bolivia: a cluster-randomized, controlled trial.

    Science.gov (United States)

    Mäusezahl, Daniel; Christen, Andri; Pacheco, Gonzalo Duran; Tellez, Fidel Alvarez; Iriarte, Mercedes; Zapata, Maria E; Cevallos, Myriam; Hattendorf, Jan; Cattaneo, Monica Daigl; Arnold, Benjamin; Smith, Thomas A; Colford, John M

    2009-08-01

    Solar drinking water disinfection (SODIS) is a low-cost, point-of-use water purification method that has been disseminated globally. Laboratory studies suggest that SODIS is highly efficacious in inactivating waterborne pathogens. Previous field studies provided limited evidence for its effectiveness in reducing diarrhoea. We conducted a cluster-randomized controlled trial in 22 rural communities in Bolivia to evaluate the effect of SODIS in reducing diarrhoea among children under the age of 5 y. A local nongovernmental organisation conducted a standardised interactive SODIS-promotion campaign in 11 communities targeting households, communities, and primary schools. Mothers completed a daily child health diary for 1 y. Within the intervention arm 225 households (376 children) were trained to expose water-filled polyethyleneteraphtalate bottles to sunlight. Eleven communities (200 households, 349 children) served as a control. We recorded 166,971 person-days of observation during the trial representing 79.9% and 78.9% of the total possible person-days of child observation in intervention and control arms, respectively. Mean compliance with SODIS was 32.1%. The reported incidence rate of gastrointestinal illness in children in the intervention arm was 3.6 compared to 4.3 episodes/year at risk in the control arm. The relative rate of diarrhoea adjusted for intracluster correlation was 0.81 (95% confidence interval 0.59-1.12). The median length of diarrhoea was 3 d in both groups. Despite an extensive SODIS promotion campaign we found only moderate compliance with the intervention and no strong evidence for a substantive reduction in diarrhoea among children. These results suggest that there is a need for better evidence of how the well-established laboratory efficacy of this home-based water treatment method translates into field effectiveness under various cultural settings and intervention intensities. Further global promotion of SODIS for general use should be

  3. Health impact assessment of Solar Disinfection (SODIS) of drinking water in three African countries

    CSIR Research Space (South Africa)

    du Preez, M

    2010-09-01

    Full Text Available .................................................................................. 48 2.6 PHASE 4: 12-MONTH MAIN SURVEY........................................................... 48 iii 2.6.1 Analytical methods ............................................................................ 50 2.6.1.1 Water quality.... .................................................................................................... 25 Figure 2.1: Schematic overview of field study schedule. ............................................ 37 Figure 2.2: Symbol Pocket PC handheld computer used to capture field data. ........... 40 Figure 2.3: Example of a monthly diarrhoeal diary...

  4. Effects of two water disinfectants (chloramine T and peracetic acid) on the epidermis and gills of Garra rufa used in human ichthyotherapy.

    Science.gov (United States)

    Sirri, R; Zaccaroni, A; Di Biase, A; Mordenti, O; Stancampiano, L; Sarli, G; Mandrioli, L

    2013-01-01

    Doctor fish (Garra rufa) have recently been used for aesthetic purposes and as a medical treatment in patients with psoriasis (ichthyotherapy). For this particular kind of human therapy it is essential to guarantee adequate hygienic conditions for both people and fish. The aim of this study was to test two concentrations of water disinfectants, chloramine T and peracetic acid, on Garra rufa to ascertain possible exposure damage to the epidermis and gills. Fish were exposed to 2 mg/l and 10 mg/l of chloramine T and to 15 microl/l and 45 microl/l of peracetic acid in a 40-minute static bath up to six times a day for one week. The epidermis and gills were checked for histological changes and the number of epidermal mucous cells, club cells and taste buds were quantified; mucous cells were also characterized histochemically to detect alterations in mucin production. No mortality or severe histological changes were found in treated or control fish. Cell count showed a significant increase (p chloramine T (mean 74.3 +/- 15.6) and with 45 microl/1 of peracetic acid (mean 78.17 +/- 10.5) compared to controls (mean 107.0 +/- 19.2). Histochemical evaluation of mucous cells did not reveal changes in mucin type in fish exposed to the two disinfectants. The results suggest a good tolerability of Garra rufa to the two disinfectants at the concentrations tested.

  5. Chemical disinfection of combined sewer overflows

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar

    for a preliminary risk assessment of disinfectants entering the aquatic ecosystem in the receiving water’s post-disinfection discharge. Performic acid (PFA) and peracetic acid (PAA) are used to disinfect CSO water, in order to reduce the number of indicator bacteria. Moreover, PFA and PAA do not form toxic by......-products when they react with the ammonia present in the CSO. Disinfectant dose and contact time in the present study were designed by disinfecting a laboratory-simulated CSO with different wastewater concentrations. Degradation kinetics of PFA and PAA in the simulated CSO as well as the disinfection efficiency...... were studied. PAA degradation in the simulated CSO was slower compared to the degradation of PFA, the latter of which, at a dose (1-8 mg/L) and with 10 minutes’ contact time, efficiently removed 4.2 logs of E. coli and 3 logs of Enterococcus spp from the simulated CSO. Furthermore, the ecotoxicity...

  6. Decontamination formulations for disinfection and sterilization

    Science.gov (United States)

    Tucker, Mark D.; Engler, Daniel E.

    2007-09-18

    Aqueous decontamination formulations that neutralize biological pathogens for disinfection and sterilization applications. Examples of suitable applications include disinfection of food processing equipment, disinfection of areas containing livestock, mold remediation, sterilization of medical instruments and direct disinfection of food surfaces, such as beef carcasses. The formulations include at least one reactive compound, bleaching activator, inorganic base, and water. The formulations can be packaged as a two-part kit system, and can have a pH value in the range of 7-8.

  7. Bactericidal activity and silver release of porous ceramic candle filter prepared by sintering silica with silver nanoparticles/zeolite for water disinfection

    Science.gov (United States)

    Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Thanh Nguyen, Duc; Hien Nguyen, Quoc

    2014-09-01

    Porous ceramic candle filters (PCCF) were prepared by sintering silica from rice husk with silver nanoparticles (AgNPs)/zeolite A at about 1050 °C to create bactericidal PCCF/AgNPs for water disinfection. The silver content in PCCF/AgNPs was of 300-350 mg kg-1 determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and the average pore size of PCCF/AgNPs was of 50-70 Å measured by Brunauer-Emmett-Teller (BET) method. The bactericidal activity and silver release of PCCF/AgNPs have been investigated by flow test with water flow rate of 5 L h-1 and initial inoculation of E. coli in inlet water of 106 CFU/100 mL. The volume of filtrated water was collected up to 500 L. Results showed that the contamination of E. coli in filtrated water was <1 CFU/100 mL and the content of silver released from PCCF/AgNPs into filtrated water was <1 μg L-1, it is low, far under the WHO guideline of 100 μg L-1 at maximum for drinking water. Based on the content of silver in PCCF/AgNPs and in filtrated water, it was estimated that one PCCF/AgNPs could be used to filtrate of ˜100 m3 water. Thus, as-prepared PCCF/AgNPs releases low content of silver into water and shows effectively bactericidal activity that is promising to apply as point-of-use water treatment technology for drinking water disinfection.

  8. Does the reuse of PET bottles during solar water disinfection pose a health risk due to the migration of plasticisers and other chemicals into the water?

    Science.gov (United States)

    Schmid, Peter; Kohler, Martin; Meierhofer, Regula; Luzi, Samuel; Wegelin, Martin

    2008-12-01

    Solar water disinfection (SODIS) is a simple, effective and inexpensive water treatment procedure suitable for application in developing countries. Microbially contaminated water is filled into transparent polyethylene terephthalate (PET) plastic bottles and exposed to full sunlight for at least 6h. Solar radiation and elevated temperature destroy pathogenic germs efficiently. Recently, concerns have been raised insinuating a health risk by chemicals released from the bottle material polyethylene terephthalate (PET). Whereas the safety of PET for food packaging has been assessed in detail, similar investigations for PET bottles used under conditions of the SODIS treatment were lacking until now. In the present study, the transfer of organic substances from PET to water was investigated under SODIS conditions using used colourless transparent beverage bottles of different origin. The bottles were exposed to sunlight for 17h at a geographical latitude of 47 degrees N. In a general screening of SODIS treated water, only food flavour constituents of previous bottle contents could be identified above a detection limit of 1 microg/L. Quantitative determination of plasticisers di(2-ethylhexyl)adipate (DEHA) and di(2-ethylhexyl)phthalate (DEHP) revealed maximum concentrations of 0.046 and 0.71 microg/L, respectively, being in the same range as levels of these plasticisers reported in studies on commercial bottled water. Generally, only minor differences in plasticiser concentrations could be observed in different experimental setups. The most decisive factor was the country of origin of bottles, while the impact of storage conditions (sunlight exposure and temperature) was less distinct. Toxicological risk assessment of maximum concentrations revealed a minimum safety factor of 8.5 and a negligible carcinogenic risk of 2.8 x 10(-7) for the more critical DEHP. This data demonstrate that the SODIS procedure is safe with respect to human exposure to DEHA and DEHP.

  9. Water disinfection by-products and the risk of specific birth defects: a population-based cross-sectional study in Taiwan

    Directory of Open Access Journals (Sweden)

    Hwang Bing-Fang

    2008-06-01

    Full Text Available Abstract Background Recent findings suggest that exposure to disinfection by-products may increase the risk of birth defects. Previous studies have focused mainly on birth defects in general or groups of defects. The objective of the present study was to assess the effect of water disinfection by-products on the risk of most common specific birth defects. Methods We conducted a population-based cross-sectional study of 396,049 Taiwanese births in 2001–2003 using information from the Birth Registry and Waterworks Registry. We compared the risk of eleven most common specific defects in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs representing high (TTHMs 20+ μg/L, medium (TTHMs 10–19 μg/L, low exposure (TTHMs 5–9 μg/L, and 0–4 μg/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and previous studies focusing on the same birth defects. Results In multivariate logistic regression analysis the risk of ventricular septal defects (adjusted odds ratio 1.81, 95% confidence interval: 0.98 3.35, cleft palate (1.56. 95% CI: 1.00, 2.41, and anencephalus (1.96, 95% CI: 0.94, 4.07 were elevated in the high exposure compared to the reference category. In the meta-analysis, the summary odds ratio for ventricular septal defects (1.59, 95% CI: 1.21, 2.07 was consistently elevated. Conclusion The present study suggests that prenatal exposure to disinfection by-products increases the risk of ventricular septal defects, cleft palate, and anencephalus. The evidence on ventricular septal defects is consistent in the three available studies.

  10. Comparison of different solar reactors for household disinfection of drinking water in developing countries: evaluation of their efficacy in relation to the waterborne enteropathogen Cryptosporidium parvum.

    Science.gov (United States)

    Gómez-Couso, H; Fontán-Sainz, M; Navntoft, C; Fernández-Ibáñez, P; Ares-Mazás, E

    2012-11-01

    Solar water disinfection (SODIS) is a type of treatment that can significantly improve the microbiological quality of drinking water at household level and therefore prevent waterborne diseases in developing countries. Cryptosporidium parvum is an obligate protozoan parasite responsible for the diarrhoeal disease cryptosporidiosis in humans and animals. Recently, this parasite has been selected by the WHO as a reference pathogen for protozoan parasites in the evaluation of household water treatment options. In this study, the field efficacy of different static solar reactors [1.5 l transparent plastic polyethylene terephthalate (PET) bottles as well as 2.5 l borosilicate glass and 25 l methacrylate reactors fitted with compound parabolic concentrators (CPC)] for solar disinfection of turbid waters experimentally contaminated with C. parvum oocysts was compared. Potential oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. The results demonstrate that static solar reactors fitted with CPCs are an excellent alternative to the conventional SODIS method with PET bottles. These reactors improved the efficacy of the SODIS method by enabling larger volumes of water to be treated and, in some cases, the C. parvum oocysts were rendered totally unviable, minimising the negative effects of turbidity. Copyright © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

  11. Prevalence and distribution of Legionella spp in potable water systems in Germany, risk factors associated with contamination, and effectiveness of thermal disinfection.

    Science.gov (United States)

    Kruse, Eva-Brigitta; Wehner, Arno; Wisplinghoff, Hilmar

    2016-04-01

    Worldwide, Legionella spp are a common cause of community-acquired pneumonia. Potable water systems are a main reservoir; however, exposure in the community is unknown. Water samples from 718 buildings in Germany were collected. Possible risk factors were prospectively recorded. All samples were tested for Legionella spp using cultural microbiologic methods. Samples were assigned to 1 of 5 levels of contamination. Statistical analysis was performed to determine the influence of risk factors for contamination and, in a subgroup of buildings, for unsuccessful thermal disinfection. In total, 4,482 water samples from 718 different water supply systems were analyzed. In 233 buildings (32.7%), Legionella spp were identified, 148 (63.5%) of which had a medium or higher level of contamination. The most common species was Legionella pneumophila (94%). Contamination was strongly associated with temperature in the circulation, but not with the size of the building, time of the year, or transport time to the laboratory. Thermal disinfection was successful in fewer than half of the buildings. There is relevant exposure to Legionella spp in the community. Water systems are not always up to current technical standards. Although microbiological risk assessment remains a challenge, there is a case for monitoring for Legionella spp outside of hospitals. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  12. Prolonged effect of two combined methods for Legionella disinfection in a hospital water system.

    Science.gov (United States)

    Casari, E; Ferrario, A; Montanelli, A

    2007-01-01

    This study was conducted in our 650 bed general hospital, which is situated on the southern outskirts of Milan (Italy). After a first nosocomial case of pneumonia (caused by Legionella pneumophila serogroup 1), we first used a conventional method (heat shock) without success. To solve the problem we then tried a copper-silver ionization system combined with a chlorine dioxide device. During the four years after the installation of these two systems we recorded a significant (p ionization system, combined with a chlorine dioxide device, is a highly promising method for the control of Legionella pneumophila in a hospital water distribution system.

  13. The alkaline comet assay used in evaluation of genotoxic damage of drinking water disinfection by-products (bromoform and chloroform

    Directory of Open Access Journals (Sweden)

    Messaouda Khallef

    2015-06-01

    Full Text Available The alkaline comet assay (pH 12.3 is a useful method for monitoring genotoxic effects of environmental pollutants in the root nuclei of Allium cepa and various plants; it allows the detection of single- and double-strand breaks, incomplete excision-repair sites and cross-links. It has been introduced to detect even small changes in DNA structure. It is a technically simple, highly sensitive, fast and economic test which detects in vitro and in vivo genotoxicity (DNA integrity and packing mode in any cell types examined, and requires just a few cells for its execution (Liman et al., 2011; Yıldız et al., 2009. Chloroform and bromoform are the most important trihalomethanes found in drinking water. Different concentrations of bromoform (25, 50, 75and 100µg/ml and chloroform (25, 50, 100 and 200 µg/ml were introduced to onion tuber roots. Distilled water was used as a negative control and methyl methansulfonate (MMS-10 µg/ml as positive control. All obtained data were subjected to statistical analyses by using SPSS 15.0 for Windows software. For comparison purposes, Duncan multiple range tests using one-way analysis of variance (ANOVA were employed and p<0.05 was accepted as the test of significance. Comet assay results showed that DNA damage was significant at p <0.05 for the different concentrations of chloroform and bromoform compared to the negative control which has a damage rate equal to 3.5 ± 0.7 and the positive control which has damage rate equal to 13.5 ± 2.12. The exposure of root tip cells to these disinfection by-products increases DNA damage. All concentrations examined in this study of bromoform and chloroform cause significant harm, which could be due to DNA damage induced by oxidative stress. The measurement of DNA damage in the nuclei of higher plant tissues is a new area of study with SCGE. This assay could be incorporated into in situ monitoring of atmosphere, water and soil: the comet assay allows a fast detection without

  14. Multi-species biofilms defined from drinking water microorganisms provide increased protection against chlorine disinfection.

    Science.gov (United States)

    Schwering, Monika; Song, Joanna; Louie, Marie; Turner, Raymond J; Ceri, Howard

    2013-09-01

    A model biofilm, formed of multiple species from environmental drinking water, including opportunistic pathogens, was created to explore the tolerance of multi-species biofilms to chlorine levels typical of water-distribution systems. All species, when grown planktonically, were killed by concentrations of chlorine within the World Health Organization guidelines (0.2-5.0 mg l(-1)). Higher concentrations (1.6-40-fold) of chlorine were required to eradicate biofilm populations of these strains, ~70% of biofilms tested were not eradicated by 5.0 mg l(-1) chlorine. Pathogenic bacteria within the model multi-species biofilms had an even more substantial increase in chlorine tolerance; on average ~700-1100 mg l(-1) chlorine was required to eliminate pathogens from the biofilm, 50-300-fold higher than for biofilms comprising single species. Confocal laser scanning microscopy of biofilms showed distinct 3D structures and multiple cell morphologies and arrangements. Overall, this study showed a substantial increase in the chlorine tolerance of individual species with co-colonization in a multi-species biofilm that was far beyond that expected as a result of biofilm growth on its own.

  15. Synthesis and characterization of ZnO nanorod films for photocatalytic disinfection of contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Juan, E-mail: rodriguezback@gmail.co [Facultad de Ciencias, Universidad Nacional de Ingenieria, P.O. Box 31-139, Av. Tupac Amaru 210, Lima (Peru); Universidad de Tarapaca, Av. General Velasquez 1775, Arica (Chile); Paraguay-Delgado, F. [Centro de Investigacion en Materiales Avanzados S. C. Miguel de Cervantes 120, Chihuahua, Chih, CP 31109 (Mexico); National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Canada T6G 2 M9 (Canada); Lopez, Alcides; Alarcon, Julio; Estrada, Walter [Facultad de Ciencias, Universidad Nacional de Ingenieria, P.O. Box 31-139, Av. Tupac Amaru 210, Lima (Peru)

    2010-11-01

    The growth of ZnO nanorods on a flat substrate was studied as a function of the main parameters used in their preparation and their ability to photocatalytically eliminate bacteria in water. The seed layer was obtained, by a spray pyrolysis technique, from a zinc acetate solution. Subsequently, to grow the rods, the seeds were immersed in a basic solution of zinc nitrate maintained at 90 {sup o}C. The growth parameters, thickness of the seed layer, acidity of the precursor solution used to obtain the seed layer, and the rate of crystal growth on the seed layer during the thermal bath treatment, were studied. The resulting materials were characterized morphologically by scanning electron microscopy and transmission electron microscopy (TEM); X-ray diffraction and TEM were used to study their structure and ultraviolet-visible spectroscopy to determine their absorbance. Most of the obtained materials were textured in the (002) direction perpendicular to the substrate. The rods have a hexagonal cross section between 60 and 150 nm. Using these rods, the photocatalytic degradation of Escherichia coli bacteria in water was studied; a positive influence of the surface area and crystalline growth on the degradation rate was observed.

  16. Solar disinfection of drinking water in the prevention of dysentery in South African children aged under 5 years: the role of participant motivation.

    Science.gov (United States)

    Du Preez, Martella; Mcguigan, Kevin G; Conroy, Ronan M

    2010-11-15

    Solar disinfection (SODIS) effectively improves the microbial quality of drinking water for preventing diarrhea; however, the effect of participant motivation has not been studied. This 1-year randomized controlled trial investigated the effect of SODIS of drinking water and motivation on the incidence of dysentery and nondysentery diarrhea among children of age 6 months to 5 years living in periurban communities in South Africa.We compared 383 children in 297 households using SODIS with 335 children in 267 households with no intervention. At baseline 62.4% of the study households had stored water which met World Health Organization guidelines for zero thermotolerant coliforms per 100 mL. Dysentery was recorded using a pictorial diary. Incidence of dysentery was significantly associated with higher motivation, defined as 75% or better completion of diarrhea data. Incidence rates were lower in those drinking solar disinfected water (incidence rate ratio 0.64, 95% CI 0.39 - 1.0, P = 0.071) but not statistically significant. Compared with the control, participants with higher motivation achieved a significant reduction in dysentery (incidence rate ratio 0.36, 95% CI 0.16 - 0.81, P = 0.014). However, there was no significant reduction in risk at lower levels of motivation. Solar disinfection was not significantly associated with nondysentery diarrhea risk overall (P = 0.419). A statistically significant reduction in dysentery was achieved only in households with higher motivation, showing that motivation is a significant determinant for measurable health gains. Failure of three-quarters of participants to achieve a significant reduction in dysentery suggests that research into effective implementation is required.

  17. Antimicrobial Resources for Disinfection of Potable Water Systems for Future Spacecraft

    Science.gov (United States)

    Morford, Megan A.; Birmele, Michele; Roberts, Michael S.

    2012-01-01

    As human exploration adventures beyond low earth orbit, life support systems will require more innovation and research to become self-sustaining and durable. One major concern about future space travel is the ability to store and decontaminate water for consumption and hygiene. This project explores materials and technologies for possible use in future water systems without requiring point-of-use (POU) filtering or chemical additives such as iodine or silver that require multiple doses to remain effective. This experimentation tested the efficacy of a variety of antimicrobial materials against biofilm formation in a high shear CDC Biofilm Reactor (CBR) and some materials in a low shear Drip Flow Reactor (DFR) which(also utilizes ultra violet light emitting diodes (UVLEDs) as an antimicrobial resource. Most materials were tested in the CBR using the ASTM E 2562-07 1method involving the Pseudomonas aeruginosa and coupon samples that vary in their antimicrobial coatings and surface layer topographies. In a controlled environmental chamber (CEC), the CBR underwent a batch phase, continuous flow phase (CFP), and a harvest before analysis. The DFR portion of this experimentation was performed in order to assess the antimicrobial capabilities of ultraviolet-A LEDs (UV-A) in potable water systems. The ASTM E 2647-08 was modified in order to incorporate UV-A LEDs and to operate as a closed, re-circulating system. The modified DFR apparatus that was utilized contains 4 separate channels each of which contain 2 UV-A LEDs (1 chamber is masked off to serve as a control) and each channel is equipped with its own reservoir and peristaltic pump head. The 10 DFR runs discussed in this report include 4 initial experimental runs that contained blank microscope slides to test the UVA LEDs alone, 2 that incorporated solid silver coupons, 2 that utilized titanium dioxide (Ti02) coupons as a photocatalyst, and 2 runs that utilized silver coated acrylic slides. Both the CBR and DFR

  18. Effect of Changing Treatment Disinfectants on the Microbiology of Distributed Water and Pipe Biofilm Communities using Conventional and Metagenomic Approaches

    Science.gov (United States)

    The purpose of this research was to add to our knowledge of chlorine and monochloramine disinfectants, with regards to effects on the microbial communities in distribution systems. A whole metagenome-based approach using sophisticated molecular tools (e.g., next generation sequen...

  19. Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams

    Science.gov (United States)

    Hladik, Michelle; Focazio, Michael J.; Engle, Mark

    2014-01-01

    Fluids co-produced with oil and gas production (produced waters) are often brines that contain elevated concentrations of bromide. Bromide is an important precursor of several toxic disinfection by-products (DBPs) and the treatment of produced water may lead to more brominated DBPs. To determine if wastewater treatment plants that accept produced waters discharge greater amounts of brominated DBPs, water samples were collected in Pennsylvania from four sites along a large river including an upstream site, a site below a publicly owned wastewater treatment plant (POTW) outfall (does not accept produced water), a site below an oil and gas commercial wastewater treatment plant (CWT) outfall, and downstream of the POTW and CWT. Of 29 DBPs analyzed, the site at the POTW outfall had the highest number detected (six) ranging in concentration from 0.01 to 0.09 μg L− 1 with a similar mixture of DBPs that have been detected at POTW outfalls elsewhere in the United States. The DBP profile at the CWT outfall was much different, although only two DBPs, dibromochloronitromethane (DBCNM) and chloroform, were detected, DBCNM was found at relatively high concentrations (up to 8.5 μg L− 1). The water at the CWT outfall also had a mixture of inorganic and organic precursors including elevated concentrations of bromide (75 mg L− 1) and other organic DBP precursors (phenol at 15 μg L− 1). To corroborate these DBP results, samples were collected in Pennsylvania from additional POTW and CWT outfalls that accept produced waters. The additional CWT also had high concentrations of DBCNM (3.1 μg L− 1) while the POTWs that accept produced waters had elevated numbers (up to 15) and concentrations of DBPs, especially brominated and iodinated THMs (up to 12 μg L− 1 total THM concentration). Therefore, produced water brines that have been disinfected are potential sources of DBPs along with DBP precursors to streams wherever these wastewaters are discharged.

  20. Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams.

    Science.gov (United States)

    Hladik, Michelle L; Focazio, Michael J; Engle, Mark

    2014-01-01

    Fluids co-produced with oil and gas production (produced waters) are often brines that contain elevated concentrations of bromide. Bromide is an important precursor of several toxic disinfection by-products (DBPs) and the treatment of produced water may lead to more brominated DBPs. To determine if wastewater treatment plants that accept produced waters discharge greater amounts of brominated DBPs, water samples were collected in Pennsylvania from four sites along a large river including an upstream site, a site below a publicly owned wastewater treatment plant (POTW) outfall (does not accept produced water), a site below an oil and gas commercial wastewater treatment plant (CWT) outfall, and downstream of the POTW and CWT. Of 29 DBPs analyzed, the site at the POTW outfall had the highest number detected (six) ranging in concentration from 0.01 to 0.09 μg L(-1) with a similar mixture of DBPs that have been detected at POTW outfalls elsewhere in the United States. The DBP profile at the CWT outfall was much different, although only two DBPs, dibromochloronitromethane (DBCNM) and chloroform, were detected, DBCNM was found at relatively high concentrations (up to 8.5 μg L(-1)). The water at the CWT outfall also had a mixture of inorganic and organic precursors including elevated concentrations of bromide (75 mg L(-1)) and other organic DBP precursors (phenol at 15 μg L(-1)). To corroborate these DBP results, samples were collected in Pennsylvania from additional POTW and CWT outfalls that accept produced waters. The additional CWT also had high concentrations of DBCNM (3.1 μg L(-1)) while the POTWs that accept produced waters had elevated numbers (up to 15) and concentrations of DBPs, especially brominated and iodinated THMs (up to 12 μg L(-1) total THM concentration). Therefore, produced water brines that have been disinfected are potential sources of DBPs along with DBP precursors to streams wherever these wastewaters are discharged. © 2013.

  1. THM reduction on water distribution network with chlorine dioxide as disinfectant; Reduccion de THM en red de distribucion utilizando dioxido de cloro como desinfectante

    Energy Technology Data Exchange (ETDEWEB)

    Ventura, G.; Gorriz, D.; Pascual, E.; Romero, M.

    2009-07-01

    A disinfectant change on water distribution network, by chlorine dioxide in that case, avoids THM formation. In the other hand it creates big doubts about utilization and analytical determination of another oxidant different to chlorine. Just a need to comply the current legislation points us to make a change as the one mentioned above and carried out in DWTP Rio Verde, being managed by Acosol, where the THM formation is been reduced to 80%, according to the new limit of 100{mu}g/l, along the 200 km of the supply network. (Author) 13 refs.

  2. Prechlorination of algae-laden water: The effects of transportation time on cell integrity, algal organic matter release, and chlorinated disinfection byproduct formation.

    Science.gov (United States)

    Qi, Jing; Lan, Huachun; Liu, Ruiping; Miao, Shiyu; Liu, Huijuan; Qu, Jiuhui

    2016-10-01

    The prechlorination-induced algal organic matter (AOM) released from Microcystis aeruginosa (M. aeruginosa) cells has been reported to serve as a source of precursors for chlorinated disinfection byproducts (DBPs). However, previous studies have mainly focused on the precursors either extracted directly from the cell suspension or derived immediately after algal suspension prechlorination. This study aims to investigate the impacts of water transportation time after algal suspension prechlorination on cell integrity, AOM release, and DBP formation during the dissolved phase chlorination. The damage to cell integrity after prechlorination was indicated to depend not only on chlorine dose but also on transportation time. The highest dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) values were observed at 2 mg/L chlorine preoxidation before transportation, but were obtained at 0.4 mg/L chlorine after 480-min simulated transportation. The variation of DON with transportation time was indicated to be mainly influenced by the small molecular weight nitrogenous organic compounds, such as amino acids. Additionally, formation of the corresponding chlorinated carbonaceous disinfection byproducts (C-DBPs) and nitrogenous disinfection byproducts (N-DBPs) during the dissolved phase chlorination showed the same variation tendency as DOC and DON respectively. The highest C-DBP (98.4 μg/L) and N-DBP (5.5 μg/L) values were obtained at 0.4 mg/L chlorine preoxidation after 480-min simulated transportation. Therefore, when prechlorination is applied for algae-laden water pretreatment, not only chlorine dose but also transportation time needs to be considered with regard to their effects on cell integrity, AOM release, and chlorinated DBP formation. Copyright © 2016. Published by Elsevier Ltd.

  3. Influence of Natural Organic Matter (NOM) Character on the Distribution of Chlorinated and Chloraminated Disinfection By-Products (DBPs) at Rand Water

    Science.gov (United States)

    Marais, Savia S.; Ncube, Esper J.; Haarhoff, Johannes; Msagati, Titus AM; Mamba, Bhekie B.; Nkambule, Thabo I.

    2016-04-01

    Certain disinfection by-products (DBPs) are likely human carcinogens or present mutagenic effects while many DBPs are unidentified. Considering the possibility of DBPs being harmful to human health and the fact that trihalomethanes (THMs) are the only regulated DBP in the South African National Standard (SANS:241) for drinking water, special interest in the precursors to these DBPs' formation is created. It is essential to understand the reactivity and character of the precursors responsible for the formation of DBPs in order to enhance precursor removal strategies during the treatment of drinking water. In this study the character of NOM within surface water and the subsequent distribution of THMs formed in the drinking water from Rand Waters' full scale treatment plant were investigated. Molecular size distribution (MSD) of NOM within the surface water was determined by high performance size exclusion chromatography (HPSEC). Specific ultraviolet absorbance (SUVA) and UV254 measurements formed part of the NOM character study as they provide an indication of the aromaticity of organic matter. The four THMs; bromoform, chloroform, dibromochloromethane (DBCM) and bromodichloromethane (BDCM)were measured by gas chromatography. The sum of these four THMs was expressed as total trihalomethane (TTHM). On average the chloroform constituted 76.2% of the total TTHM, BDCM 22.5% while DBCM and bromoform measured below the detection limit. THM speciation after chlorination and chloramination concentrations increased in the sequence bromoform NOM of high molecular size (peak I) and TTHM formation specifically during the summer months (R2= 0.971, p NOM also related well to chloroform formation (R2 = 0.963, p NOM character was evident in the source water in summer when high temperatures and rainfall occurred. The results displayed are an indication that aromatic NOM were the main precursor to TTHM formation, more prominently during summer. Keywords: disinfection by

  4. Removal of the precursors of N-nitrosodiethylamine (NDEA), an emerging disinfection byproduct, in drinking water treatment process and its toxicity to adult zebrafish (Danio rerio).

    Science.gov (United States)

    Zheng, Jian; Lin, Tao; Chen, Wei

    2018-01-01

    N-nitrosodiethylamine (NDEA) is one of the emerging nitrogenous disinfection byproducts with probable cytotoxicity, genotoxicity, and carcinogenesis. Its potential toxicological effects have received extensive attention but remain to be poorly understood. In this study, changes in NDEA precursors in drinking water treatment process were studied using the trial of its formation potential (FP), and the toxicity induced by NDEA to adult zebrafish was investigated. NDEA FP in the raw water of Taihu Lake ranged from 46.9 to 68.3 ng/L. The NDEA precursors were removed effectively by O3/BAC process. Hydrophilic fraction and low-molecular-weight fraction (water treatment process and its toxicity effect on zebrafish as a model animal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Real-time determination of the efficacy of residual disinfection to limit wastewater contamination in a water distribution system using filtration-based luminescence.

    Science.gov (United States)

    Lee, Jiyoung; Deininger, Rolf A

    2010-05-01

    Water distribution systems can be vulnerable to microbial contamination through cross-connections, wastewater backflow, the intrusion of soiled water after a loss of pressure resulting from an electricity blackout, natural disaster, or intentional contamination of the system in a bioterrrorism event. The most urgent matter a water treatment utility would face in this situation is detecting the presence and extent of a contamination event in real-time, so that immediate action can be taken to mitigate the problem. The current approved microbiological detection methods are culture-based plate count methods, which require incubation time (1 to 7 days). This long period of time would not be useful for the protection of public health. This study was designed to simulate wastewater intrusion in a water distribution system. The objectives were 2-fold: (1) real-time detection of water contamination, and (2) investigation of the sustainability of drinking water systems to suppress the contamination with secondary disinfectant residuals (chlorine and chloramine). The events of drinking water contamination resulting from a wastewater addition were determined by filtration-based luminescence assay. The water contamination was detected by luminescence method within 5 minutes. The signal amplification attributed to wastewater contamination was clear-102-fold signal increase. After 1 hour, chlorinated water could inactivate 98.8% of the bacterial contaminant, while chloraminated water reduced 77.2%.

  6. Concentration, chlorination, and chemical analysis of drinking water for disinfection byproduct mixtures health effects research: U.S. EPA's Four Lab Study.

    Science.gov (United States)

    Pressman, Jonathan G; Richardson, Susan D; Speth, Thomas F; Miltner, Richard J; Narotsky, Michael G; Hunter, E Sidney; Rice, Glenn E; Teuschler, Linda K; McDonald, Anthony; Parvez, Shahid; Krasner, Stuart W; Weinberg, Howard S; McKague, A Bruce; Parrett, Christopher J; Bodin, Nathalie; Chinn, Russell; Lee, Chih-Fen T; Simmons, Jane Ellen

    2010-10-01

    The U.S. Environmental Protection Agency's "Four Lab Study" involved participation of researchers from four national Laboratories and Centers of the Office of Research and Development along with collaborators from the water industry and academia. The study evaluated toxicological effects of complex disinfection byproduct (DBP) mixtures, with an emphasis on reproductive and developmental effects that have been associated with DBP exposures in some human epidemiologic studies. This paper describes a new procedure for producing chlorinated drinking water concentrate for animal toxicology experiments, comprehensive identification of >100 DBPs, and quantification of 75 priority and regulated DBPs. In the research reported herein, complex mixtures of DBPs were produced by concentrating a natural source water with reverse osmosis membranes, followed by addition of bromide and treatment with chlorine. By concentrating natural organic matter in the source water first and disinfecting with chlorine afterward, DBPs (including volatiles and semivolatiles) were formed and maintained in a water matrix suitable for animal studies. DBP levels in the chlorinated concentrate compared well to those from EPA's Information Collection Rule (ICR) and a nationwide study of priority unregulated DBPs when normalized by total organic carbon (TOC). DBPs were relatively stable over the course of the animal studies (125 days) with multiple chlorination events (every 5-14 days), and a significant portion of total organic halogen was accounted for through a comprehensive identification approach. DBPs quantified included regulated DBPs, priority unregulated DBPs, and additional DBPs targeted by the ICR. Many DBPs are reported for the first time, including previously undetected and unreported haloacids and haloamides. The new concentration procedure not only produced a concentrated drinking water suitable for animal experiments, but also provided a greater TOC concentration factor (136

  7. New disinfection and sterilization methods.

    Science.gov (United States)

    Rutala, W A; Weber, D J

    2001-01-01

    New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxide sterilization (Attest), and a hydrogen peroxide plasma sterilizer that has a shorter cycle time and improved efficacy (Sterrad 50).

  8. Stormwater disinfection using Electrochemical oxidation

    OpenAIRE

    WENJUN FENG

    2017-01-01

    This thesis demonstrates that electrochemical oxidation can be a promising stormwater disinfection technique to achieve regulatory water re-uses targets. It discusses the implications for the practical implementation of the technology and identifies areas for future research in regards to optimisation of the technology

  9. Enhanced formation of bromate and brominated disinfection byproducts during chlorination of bromide-containing waters under catalysis of copper corrosion products.

    Science.gov (United States)

    Hu, Jun; Qiang, Zhimin; Dong, Huiyu; Qu, Jiuhui

    2016-07-01

    Copper corrosion products (CCPs) in water distribution pipes may catalyze the reactions among disinfectant, natural organic matter (NOM), and bromide (Br(-)). This study investigated the simultaneous formation of bromate (BrO3(-)) and brominated disinfection byproducts (Br-DBPs) during chlorination of Br(-)-containing waters in the presence of three CCPs (i.e., CuO, Cu2O, and Cu(2+)). In a synthetic water, both oxidant decay and BrO3(-) formation were enhanced by CCPs, whereas the presence of humic acid (HA) significantly inhibited BrO3(-) formation due to its competition for HOBr to form Br-DBPs. In the HOClBr(-)CuO system, the BrO3(-) yield increased obviously with increasing CuO dose and initial Br(-) concentration, while the catalytic formation of Br-DBPs was rather limited. A molar conversion (Br(-) to BrO3(-)) of 22.1% was observed under CuO catalysis, compared with little conversion in the absence of CuO. In the HOClBr(-)Cu2O/Cu(2+) systems, Cu2O or Cu(2+) mainly enhanced the formation of Br-DBPs, with enhancement ratios of 69.9% and 50.1%, respectively. The degree of enhancement on Br-DBPs formation became more apparent with increasing pH, while that on BrO3(-) formation reached maximal at pH 7.6. The catalytic formation of Br-DBPs and BrO3(-) by CCPs was also verified in three filtered real waters, although to a lesser extent because of the water matrix effect. In mechanism, the CCPs promoted the formation of BrO3(-) and Br-DBPs through catalyzing the HOBr disproportionation pathway and the reaction of HOBr toward HA, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Source Water Management for Disinfection By-Product Control using New York City's Operations Support Tool and On-Line Monitoring

    Science.gov (United States)

    Weiss, W. J.; Becker, W.; Schindler, S.

    2012-12-01

    The United States Environmental Protection Agency's 2006 Stage 2 Disinfectant / Disinfection Byproduct Rule (DBPR) for finished drinking waters is intended to reduce overall DBP levels by limiting the levels of total trihalomethanes (TTHM) and five of the haloacetic acids (HAA5). Under Stage 2, maximum contaminant levels (MCLs), 80 μg/L for TTHM and 60 μg/L for HAA5, are based on a locational running annual average for individual sites instead of as the system-wide quarterly running annual average of the Stage 1 DBPR. This means compliance will have to be met at sampling locations of peak TTHM and HAA5 concentrations rather than an average across the entire system. Compliance monitoring under the Stage 2 DBPR began on April 1, 2012. The New York City (NYC) Department of Environmental Protection (DEP) began evaluating potential impacts of the Stage 2 DBPR on NYC's unfiltered water supply in 2002 by monitoring TTHM and HAA5 levels at various locations throughout the distribution system. Initial monitoring indicated that HAA5 levels could be of concern in the future, with the potential to intermittently violate the Stage 2 DBPR at specific locations, particularly those with high water age. Because of the uncertainty regarding the long-term prospect for compliance, DEP evaluated alternatives to ensure compliance, including operational changes (reducing chlorine dose, changing flow configurations to minimize water age, altering pH, altering source water withdrawals); changing the residual disinfectant from free chlorine to chloramines; and engineered treatment alternatives. This paper will discuss the potential for using DEP's Operations Support Tool (OST) and enhanced reservoir monitoring to support optimization of source water withdrawals to minimize finished water DBP levels. The OST is a state-of-the-art decision support system (DSS) to provide computational and predictive support for water supply operations and planning. It incorporates a water supply system

  11. Occurrence and Spatial and Temporal Variations of Disinfection By-Products in the Water and Air of Two Indoor Swimming Pools

    Directory of Open Access Journals (Sweden)

    Tardif Robert

    2012-07-01

    Full Text Available In order to improve disinfection by-product (DBP exposure assessment, this study was designed to document both water and air levels of these chemical contaminants in two indoor swimming pools and to analyze their within-day and day-to-day variations in both of them. Intensive sampling was carried out during two one-week campaigns to measure trihalomethanes (THMs and chloramines (CAMs in water and air, and haloacetic acids (HAAs in water several times daily. Water samples were systematically collected at three locations in each pool and air samples were collected at various heights around the pool and in other rooms (e.g., changing room in the buildings. In addition, the ability of various models to predict air concentrations from water was tested using this database. No clear trends, but actual variations of contamination levels, appeared for both water and air according to the sampling locations and times. Likewise, the available models resulted in realistic but imprecise estimates of air contamination levels from water. This study supports the recommendation that suitable minimal air and water sampling should be carried out in swimming pools to assess exposure to DBPs.

  12. Using limes and synthetic psoralens to enhance solar disinfection of water (SODIS): a laboratory evaluation with norovirus, Escherichia coli, and MS2.

    Science.gov (United States)

    Harding, Alexander S; Schwab, Kellogg J

    2012-04-01

    We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Slurry and 5.6 logs by SODIS + Lime Juice in 30-minute solar exposures, compared with a 1.5 log reduction with SODIS alone (N = 3; P 3.9 logs by SODIS + Lime Slurry, 1.9 logs by SODIS + Lime Juice, and 1.4 logs by SODIS in 2.5-hour solar exposures (N = 3; P SODIS, with SODIS against human norovirus should be investigated further.

  13. An Evaluation of the Quality of the Desinfection Process in Inanimated Surfaces of Basic Health Units by Biomarkers Research

    Directory of Open Access Journals (Sweden)

    Ana Paula Bandeira Fucci

    2013-06-01

    Full Text Available Infection Related Health Care – IRHC may occur by exogenous transmission through the contamination of contaminated surfaces. This study aimed at verifying the quality of the process of disinfecting inanimate surfaces of Basic Health Units – BHU in a northeastern city in São Paulo state, through the presence of biomarkers, Staphylococcus aureus and Escherichia coli. We evaluated 7 UBS in random times and days, covering the following areas: dressing-room doorknob, drinking fountains and faucets, office desk, reception counter. Sterile swabs were rubbed on a 20 cm2 surface and transported to the laboratory in Stuart medium to the Clinical Analyses Didactic Laboratory of UNIFEV. The samples were cultured on Blood agar and MacConkey agar at 35 ± 1oC for 24 hours in aerobic and microaerophilic jar, respectively. Staphylococcus aureus was identified by the production of hemolysin, catalase and coagulase. Escherichia coli was identified using the biochemical tests: TSI, citrate, urease, indole, lysine, ornithine and arginine. Of the 105 samples analyzed, 6.66% of the samples were positive for Staphylococcus aureus and Escherichia coli to 2.85%. The Areas which showed the presence of biomarkers were: the reception booth, booth pharmacy, handles of the dressing room, dressing room faucet and drinking fountain. These results corroborate other studies that show that inanimate surfaces are important sources of contamination in the healthcare environment, contributing to crosscontamination and, consequently, to the increase of infection to the patient who is subjected to procedures in this environment. Within this context, government, by means of public health policies, is responsible for the training of health professionals, contributing to the promotion and prevention of public health

  14. Optical monitoring of Disinfection By-product Precursors with Fluorescence Excitation-Emission Mapping (F-EEM): Practical Application Issues for Drinking, Waste and Reuse Water Industry

    Science.gov (United States)

    Gilmore, A. M.

    2012-12-01

    Drinking water, wastewater and reuse plants must deal with regulations associated with bacterial contamination and halogen disinfection procedures that can generate harmful disinfection by-products (DBPs) including trihalomethanes (THMs), haloacetic acids (HOAAs) and other compounds. The natural fluorescent chromophoric dissolved organic matter (CDOM) is regulated as the major DBP precursor. This study outlines the advantages and current limitations associated with optical monitoring of water treatment processes using tcontemporary Fluorescence Excitation-Emission Mapping (F-EEM). The F-EEM method coupled with practical peak indexing and multi-variate analyses is potentially superior in terms of cost, speed and sensitivity over conventional total organic carbon (TOC) meters and specific UV-absorbance (SUVA) measurements. Hence there is strong interest in developing revised environmental regulations around the F-EEM technique instruments which can incidentally simultaneously measure the SUVA and DOC parameters. Importantly, the F-EEM technique, compared to the single-point TOC and SUVA signals can resolve CDOM classes distinguishing those that strongly cause DBPs. The F-EEM DBP prediction method can be applied to surface water sources to evaluate DBP potential as a function of the point sources and reservoir depth profiles. It can also be applied in-line to rapidly adjust DOC removal processes including sedimentation-flocculation, microfiltration, reverse-osmosis, and ozonation. Limitations and interferences for F-EEMs are discussed including those common to SUVA and TOC in contrast to the advantages including that F-EEMs are less prone to interferences from inorganic carbon and metal contaminations and require little if any chemical preparation. In conclusion, the F-EEM method is discussed in terms of not only the DBP problem but also as a means of predicting (concurrent to DBP monitoring) organic membrane fouling in water-reuse and desalination plants.

  15. In vitro antimicrobial activity of three new generation disinfectants

    African Journals Online (AJOL)

    It has broad spectrum of activity against bacteria, viruses, protozoan cysts, algae and animal planktons, both dissolved in water and gas phase. Its bactericidal activity remains constant over a broader pH range from pH 3 to 8. ClO2 has been used for many disinfection procedures such as water disinfection. In water, chlorine.

  16. USING MEMBRANES TO CONCENTRATE DISINFECTION BYPRODUCTS FOR SUBSEQUENT HEALTH EFFECTS STUDIES

    Science.gov (United States)

    Chemical disinfection of water is a major public health advance that has decreased dramatically water-borne disease. Disinfecting agents react with naturally occurring organic and inorganic matter in water to produce a wide variety of disinfection byproducts (DBPs). Although mo...

  17. The influence of disinfectants on mutagenicity and on toxicity of urban waste water; Valutazione di trattamenti di disinfezione di acque reflue urbane mediante test di tossicita' e di mutagenesi

    Energy Technology Data Exchange (ETDEWEB)

    Monarca, S. [Brescia Univ., Brescia (IT). Dipt. di Medicina Sperimentale e Applicata] [and others

    1999-12-01

    The aim of the research was to study the influence of disinfectants alternative to chlorine, such as chlorine dioxide, ozone, peracetic acid and UV radiation, have on the formation of mutagenic and toxic compounds in waste water disinfection. Preliminary results are presented and discussed. [Italian] Scopo del lavoro e' stato lo studio dell'azione antimicrobica di diversi disinfettanti su acque reflue urbane dopo trattamento secondario, correlando tale parametro con l'attivita' tossica e genotossica prodotta dalla disinfezione. I risultati vengono presentati e discussi.

  18. Field comparison of solar water disinfection (SODIS) efficacy between glass and polyethylene terephalate (PET) plastic bottles under sub-Saharan weather conditions.

    Science.gov (United States)

    Asiimwe, J K; Quilty, B; Muyanja, C K; McGuigan, K G

    2013-12-01

    Concerns about photodegradation products leaching from plastic bottle material into water during solar water disinfection (SODIS) are a major psychological barrier to increased uptake of SODIS. In this study, a comparison of SODIS efficacy using glass and plastic polyethylene terephalate (PET) bottles was carried out under strong real sunlight and overcast weather conditions at Makerere University in central Uganda. Both clear and turbid natural water samples from shallow wells and open dug wells, respectively, were used. Efficacy was determined from the inactivation of a wild strain of Escherichia coli in solar-exposed contaminated water in both glass and PET bottles. The studies reveal no significant difference in SODIS inactivation between glass and PET bottles (95% CI, p > 0.05), for all water samples under the different weather conditions except for clear water under overcast conditions where there was a small but significant difference (95% CI, p = 0.047) with less viable bacterial counts in PET bottles at two intermediate time points but not at the end of the exposure. The results demonstrate that SODIS efficacy in glass under tropical field conditions is comparable to PET plastic. SODIS users in these regions can choose either of reactors depending on availability and preference of the user.

  19. Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region.

    Science.gov (United States)

    Ndounla, J; Pulgarin, C

    2015-11-01

    The photo-disinfection of natural alkaline surface water (pH 8.6 ± 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2(-), NO3(-), NH4(+), HPO4(2-), and bicarbonate (HCO3(-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.

  20. Ozonization effects on trihalo methane formation during the disinfection of drinking water with chlorine; Efectos de la ozonizacion sobre la formacion de trihalometanos durante la desinfeccion final del agua potable con cloro

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Vidal, F. J.; Perez Serrano, A.; Orozco Barrentxea, C.; Sanllorente Santamaria, M. C.; Ibeas Reoyo, M. V.

    2001-07-01

    One of the main aspects in the control of drinking water treatment is the formation of disinfection by-products (DBP), some of the most important are the trihalomethanes (THM). The use of ozone as primary disinfectant in drinking water treatment plants reduces noticeably the amount of THM generated after the chlorination at the end of the treatment. The aim of this work is to study the main factors influencing the ozone effect in this process: the delay between the time of ozonization and chlorination, the applied ozone dose and the presence of bromide ion ind the raw water. These factors have been studied on natural waters (Uzquiza Reservoir-Burgos) and on synthetic waters (fulvic and humic acids extracted from the mentioned reservoir). (Author) 36 refs.

  1. The use of ozonation and catalytic ozonation combined with ultrafiltration for the control of natural organic matter (NOM) and disinfection by-products (DBPs) in drinking water

    Science.gov (United States)

    Karnik, Bhavana Sushilkumar

    Commercially available titania membranes, with a molecular weight cut-off of 15, 5, 1 kD were used in a ozonation/membrane system that was fed with water from Lake Lansing. The effects of ozonation on permeate flux recovery and membrane fouling was investigated. In addition the effects of ozonation/membrane filtration hybrid process on the removal of the natural organic matter (NOM) and the formation of disinfection by-products (DBPS) were monitored. The commercial membrane (CeRAM Inside, Tami North America, St. Laurent, Quebec, Canada) was coated with iron oxide nanoparticles (4--6 nm in diameter) using a layer-by-layer technique and sintered in air for 30 minutes. Surface characterization was carried out using electron microscopy techniques and atomic force microscopy, to study the changes in structure and surface morphology of the membranes. The removal and survival of bacteria in the process was also evaluated using fluorescence microscopy and microbial assays. Finally the surface catalytic reaction was investigated to propose the mechanism responsible for the improved performance of the hybrid process. The permeate flux through a titania coated ceramic membrane was significantly affected by ozonation. A minimum threshold ozone concentration (2.5 g/m 3) could achieve complete recovery of permeate flux after fouling. Ozonation/filtration decreased the concentration of chlorinated disinfection by-products up to 80%. With catalyst coated membranes, the concentration of dissolved organic carbon was reduced by >85% and the concentrations of disinfection by-products decreased by up to 90%. Furthermore with the coated membrane, the concentrations of ozonation by-products in the permeate were reduced by >50% as compared to that obtained with the uncoated membranes, thus reducing the risk of potential regrowth of bacteria in the distribution system. Application of the hybrid process lead to greater than 7 log removal of bacteria. Surface characterization showed that

  2. Chemical degradation of drinking water disinfection byproducts by millimeter-sized particles of iron-silicon and magnesium-aluminum alloys.

    Science.gov (United States)

    Li, Tianyu; Chen, Yongmei; Wan, Pingyu; Fan, Maohong; Yang, X Jin

    2010-03-03

    The candidature of Fe-Si and Mg-Al alloys at millimeter-scale particle sizes for chemical degradation of disinfection byproducts (DBPs) in drinking water systems was substantiated by their enhanced corrosion resistance and catalytic effect on the degradation. The Mg-Al particles supplied electrons for reductive degradation, and the Fe-Si particles acted as a catalyst and provided the sites for the reaction. The alloy particles are obtained by mechanical milling and stable under ambient conditions. The proposed method for chemical degradation of DBPs possesses the advantages of relatively constant degradation performance, long-term durability, no secondary contamination, and ease of handling, storage and maintenance in comparison with nanoparticle systems.

  3. Effects of ozone pretreatment on the formation of disinfection by-products and its associated bromine substitution factors upon chlorination/chloramination of Tai Lake water.

    Science.gov (United States)

    Wang, Fangyuan; Ruan, Mengyong; Lin, Hongjun; Zhang, Yu; Hong, Huachang; Zhou, Xiaoling

    2014-03-15

    This study investigated the effects of preozonation on disinfection by-products (DBPs) formation during chlorination and chloramination of the water collected from Tai Lake. Results showed that the high ozone dose (0.6-1.0 mg O₃/mg DOC) pretreatment reduced the yields of trihaloacetic acids (reduced 62-63% in chlorination), dihaloacetonitriles (reduced 53-55% and 14-26% in chlorination and chloramination, respectively) and trihaomethanes (reduced 19% in chloramination), but markedly increased the formation of halonitromethanes (increased 4.7-5.6 times in chlorination and 2.1-2.7 times in chloramination), haloketones (increased 4.8-7.1 times in chlorination and 2.5-2.9 times in chloramination) and dihaloacetic acids (increased 1.5-2.4 times in chlorination and 0.3-0.6 times in chloramination). Thus the high ozone dose pretreatment should be avoided during chlorination/chloramination of Tai Lake water. Also, chloramination (with and without preozonation) produced much lower DBPs yields as compared with chlorination (with and without preozonation), indicating that chloramine was a better choice to control the DBPs yields. Further analysis also revealed that the bromine substitution factors (BSFs) of DBPs varied with disinfection mode. In chlorinamination, the BSFs generally showed a decrease trend with the ozone dose, yet in chlorination, the BSFs mostly exhibited first an increase and then a decrease trend. Moreover, the BSFs of DBPs in chloramination (with or without preozonation) were dominantly lower than those in chlorination (with or without preozonation). Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Evaluation of Alternative Methods for Wastewater Disinfection

    Science.gov (United States)

    1994-09-01

    viruses in water and wastewater (Trojan, undated:l). Used properly, ultraviolet light can effectively destroy bacteria, viruses, algae and other...highly effective in disinfecting wastewaters of an industrial nature and viable for medium to large plants, where purified oxygen is readily available or...Alternatives This appendix provides information and cost data obtained from vendors in the wastewater disinfection industry . This data is provided for

  5. Sequential disinfection of E. coli O157:H7 on shredded lettuce leaves by aqueous chlorine dioxide, ozonated water, and thyme essential oil

    Science.gov (United States)

    Singh, Nepal; Singh, Rakesh K.; Bhunia, Arun K.; Stroshine, Richard L.; Simon, James E.

    2001-03-01

    There have been numerous studies on effectiveness of different sanitizers for microbial inactivation. However, results obtained from different studies indicate that microorganism cannot be easily removed from fresh cut vegetables because of puncture and cut surfaces with varying surface topographies. In this study, three step disinfection approach was evaluated for inactivation of E. coli O157:H7 on shredded lettuce leaves. Sequential application of thyme oil, ozonated water, and aqueous chlorine dioxide was evaluated in which thyme oil was applied first followed by ozonated water and aqueous chlorine dioxide. Shredded lettuce leaves inoculated with cocktail culture of E. coli O157:H7 (C7927, EDL 933 and 204 P), were washed with ozonated water (15 mg/l for 10min), aqueous chlorine dioxide (10 mg/l,for 10min) and thyme oil suspension (0.1%, v/v for 5min). Washing of lettuce leaves with ozonated water, chlorine dioxide and thyme oil suspension resulted in 0.44, 1.20, and 1.46 log reduction (log10 cfu/g), respectively. However, the sequential treatment achieved approximately 3.13 log reductions (log10 cfu/g). These results demonstrate the efficacy of sequential treatments in decontaminating shredded lettuce leaves containing E. coli O157:H7.

  6. A preliminary Ames fluctuation assay assessment of the genotoxicity of drinking water that has been solar disinfected in polyethylene terephthalate (PET) bottles.

    Science.gov (United States)

    Ubomba-Jaswa, Eunice; Fernández-Ibáñez, Pilar; McGuigan, Kevin G

    2010-12-01

    Though microbially safe, concerns have been raised about the genotoxic/mutagenic quality of solar-disinfected drinking water, which might be compromised as a result of photodegradation of polyethylene terephthalate (PET) bottles used as SODIS reactors. This study assessed genotoxic risk associated with the possible release of genotoxic compounds into water from PET bottles during SODIS, using the Ames fluctuation test. Negative genotoxicity results were obtained for water samples that had been in PET bottles and exposed to normal SODIS conditions (strong natural sunlight) over 6 months. Under SODIS conditions, bottles were exposed to 6 h of sunlight, followed by overnight room temperature storage. They were then emptied and refilled the following day and exposed to sunlight again. Genotoxicity was detected after 2 months in water stored in PET bottles and exposed continuously (without refilling) to sunlight for a period ranging from 1 to 6 months. However, similar genotoxicity results were also observed for the dark control (without refill) samples at the same time-point and in no other samples after that time; therefore it is unlikely that this genotoxicity event is related to solar exposure.

  7. ASSESSMENT OF THE EFFICIENCY OF DISINFECTION METHOD ...

    African Journals Online (AJOL)

    eobe

    The efficiencies of three disinfection methods namely boiling, water guard and pur purifier were assessed. ... Water is an indispensable resource for supporting life systems [2-. 4], while access to safe drinking water is a basic human right, which is essential for healthy life ...... developing country context: improving decisions.

  8. Disinfection of water using solar energy (SODIS): inactivation and reactivation of bacteria; Desinfeccao de agua utilizando energia solar (SODIS): inativacao e recrescimento bacteriano

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcelo Jacomini Moreira da

    2004-07-01

    Besides being an available natural source, the solar energy is very applicable in places where there are bad recourses and low money resources, because there are not either the need of chemical products neither a huge cost (commercial materials can be re-used). To make this job we used re-used half painted black PET bottles with the variables: exposed to heat times: 1, 2, 4 e 6 hours and we used also a concentrator of rays of sunshine. The affluent control parameters were: turbidity, apparent color, temperature, total coliforms and E. coli. The effluent parameters were just the last three: temperature, total coliforms and E.coli. To asses the bacteria reactivation the water was kept in bottles for 24 hours, pretending a situation that is very common in brazilian rural houses. We conclude that the use of the concentrator of rays of sunshine can reduce the exposition to heat from 6 to 4 hours, without prejudice the SODIS efficiency and using the concentrator of rays of sunshine for 6 hours we can obtain the process of solar pasteurization (SOPAS), with a 70 deg C water temperature and stopping the re-growth of bacteria. We also observed that when there are clouds in the sky the incidence of solar radiation and the SODIS efficiency decrease, even if the water temperature is higher during the disinfection, although this factor does not mean a significant influence statistically. (author)

  9. High compliance randomized controlled field trial of solar disinfection of drinking water and its impact on childhood diarrhea in rural Cambodia.

    Science.gov (United States)

    McGuigan, Kevin G; Samaiyar, Priyajit; du Preez, Martella; Conroy, Ronán M

    2011-09-15

    Recent solar disinfection (SODIS) studies in Bolivia and South Africa have reported compliance rates below 35% resulting in no overall statistically significant benefit associated with disease rates. In this study, we report the results of a 1 year randomized controlled trial investigating the effect of SODIS of drinking water on the incidence of dysentery and nondysentery diarrhea among children of age 6 months to 5 years living in rural communities in Cambodia. We compared 426 children in 375 households using SODIS with 502 children in 407 households with no intervention. Study compliance was greater than 90% with only 5% of children having less than 10 months of follow-up and 2.3% having less than 6 months. Adjusted for water source type, children in the SODIS group had a reduced incidence of dysentery, with an incidence rate ratio (IRR) of 0.50 (95% CI 0.27-0.93, p = 0.029). SODIS also had a protective effect against nondysentery diarrhea, with an IRR of 0.37 (95% CI 0.29-0.48, p SODIS is an effective and culturally acceptable point-of-use water treatment method in the culture of rural Cambodia and may be of benefit among similar communities in neighboring South East Asian countries.

  10. The efficacy of potassium ferrate as a chemical disinfectant on E. coli, Vibrio cholera, human adenovirus, and Giardia lamblia

    Science.gov (United States)

    Introduction: Drinking water and wastewater go through numerous treatments to remove microorganisms and other contaminants one of many processes along the treatment train is disinfection. There are different ways to disinfect these waters, however to date the most common disinf...

  11. Simultaneous Determination of Disinfection By-products in Water Samples from Advanced Membrane Treatments by Headspace Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    C. Martínez

    2014-01-01

    Full Text Available A headspace-solid phase microextraction (HS-SPME and gas chromatography-mass spectrometry (GC-MS method has been developed for the simultaneously determination of 20 disinfection by-products (DBPs in water samples from reverse osmosis (RO membranes. Selected compounds belong to different families including: trihalomethanes (THMs, halogenated acetonitriles (HANs, halogenated nitromethanes (HNMs, halogenated ketones (HKs and other halogenated DBPs. Four commercial fibres with different polarities were tested for the extraction of the compounds and the main variables affecting HS-SPME such as extraction time, extraction temperature and pH of the samples were optimized by applying a central composite design. The method showed good detection limits in the range of 0.003 g l-1 up to 0.010 g l-1 for most of the compounds with reasonable linearity with r2 higher than 0.991. Moreover, the repeatability of the method, expressed as relative standard deviation (RSD was lower than 13% (n = 5, 1 g l-1 in brackish and wastewater samples. The validated method has been applied for the determination of the target DBPs in RO water samples from application research units, which treated water from various origins (wastewater, brackish water and sea water, showing good performance in the different types of studied samples. The analysis revealed the presence of several DBPs regarding different families, such as trichloromethane (with concentrations up to 0.36 μg l -1 , chloroiodomethane (0.5-1.44 μg l -1 , dibromochloromethane (found at concentrations up to 0.76 μg l -1 and tribromoacetaldehyde (at concentrations up to 11 μg l -1 in the influent samples. The tendency of most of them indicated a trend of removal by reverse osmosis treatments, especially the total concentration of THMs which decreased below the limit of detection.

  12. Photodecomposition of humic acid and natural organic matter in swamp water using a TiO(2)-coated ceramic foam filter: potential for the formation of disinfection byproducts.

    Science.gov (United States)

    Mori, Masanobu; Sugita, Tsuyoshi; Mase, Akinori; Funatogawa, Takahiro; Kikuchi, Masaru; Aizawa, Kazuhiko; Kato, Shigekazu; Saito, Yoichi; Ito, Tsukasa; Itabashi, Hideyuki

    2013-01-01

    This paper reports on the photodecomposition of aqueous humic acid (HA) by a TiO(2)-coated ceramic foam filter (TCF) reactor and on the potential for the formation of disinfection byproducts (DBPs) upon chlorination of the photocatalytically treated solutions. This photocatalytic reactor can also be applied to the removal of natural organic matter (NOM) in swamp waters. The proposed photocatalytic reaction system was operated as per standardized methodologies. First, the ability of the TCF to decompose HA (a representative compound of NOM) was evaluated from the changes in the total organic carbon (TOC) and UV(254) with the reaction time. Remarkably, TOC removal and UV(254) values ranging from 44% to 61% and from 60% to 83%, respectively, were achieved. The potential for the formation of DBPs (total trihalomethane and total haloacetic acid) by chlorination of the phototreated solution was strongly dependent on the TOC removal and UV(254) values in the solution. The degree of photodecomposition of NOMs in the swamp water samples and the DBP formation potential showed similar trends as in the case of the standard solutions containing HA. The method used in this study could be effectively used to evaluate the efficiency of TCF for reducing HA and NOM, while suppressing the formation of DBP products. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Adsorption of natural organic matter and disinfection byproduct precursors from surface water onto TiO2nanoparticles: pH effects, isotherm modelling and implications for using TiO2for drinking water treatment.

    Science.gov (United States)

    Gora, Stephanie L; Andrews, Susan A

    2017-05-01

    Titanium dioxide is a photocatalyst that can remove organic contaminants of interest to the drinking water treatment industry, including natural organic matter (NOM) and disinfection byproduct (DBP) precursors. The photocatalytic reaction occurs in two steps: adsorption of the contaminant followed by degradation of the adsorbed contaminant upon irradiation with UV light. The second part of this process can lead to the formation of reactive intermediates and negative impacts on treated water quality, such as increased DBP formation potential (DBPfp). Adsorption alone does not result in the formation of reactive intermediates and thus may prove to be a safe way to incorporate TiO 2 into drinking water treatment processes. The goal of this study was to expand on the current understanding of NOM adsorption on TiO 2 and examine it in a drinking water context by observing NOM adsorption from real water sources and evaluating the effects of the resulting reductions on the DBPfp of the treated water. Bottle point isotherm tests were conducted with raw water from two Canadian water treatment plants adjusted to pH 4, pH 6 and pH 8 and dosed with TiO 2 nanoparticles. The DOC results were a good fit to a modified Freundlich isotherm. DBP precursors and liquid chromatography with organic carbon detection NOM fractions associated with DBP formation were removed to some extent at all pHs, but most effectively at pH 4. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Zero-G Condensing Heat Exchanger with Integral Disinfection

    Science.gov (United States)

    Burke, Kenneth A. (Inventor)

    2012-01-01

    The system that operates in a zero gravity environment and has an integral ozone generating capability is disclosed. The system contributes to the control of metabolic water vapors in the air, and also provided disinfection of any resulting condensate within the system, as well as disinfection of the air stream that flows throughout the disclosed system.

  15. A biocoagulant slow sand filtration for disinfection of Toxoplasma ...

    African Journals Online (AJOL)

    Considering that is widely used for various domestic chores; filtration disinfection of T. gondii was considered. A bench scale disinfection of oocysts of T. gondii with 0.2 g of powdered Moringa oleifera seeds per 10 ml of contaminated water from Mezam River showed a reduction of 50 oocysts per 10 ml to 10 oocysts in 15 ...

  16. 40 CFR 141.65 - Maximum residual disinfectant levels.

    Science.gov (United States)

    2010-07-01

    ... following as the best technology, treatment techniques, or other means available for achieving compliance... treatment processes to reduce disinfectant demand and control of disinfection treatment processes to reduce.... 141.65 Section 141.65 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER...

  17. Chemical disinfection of combined sewer overflows

    DEFF Research Database (Denmark)

    Chhetri, Ravi Kumar

    of the residual disinfectants PFA, PAA and chlorine dioxide (ClO2), and their degradation products hydrogen peroxide and chlorite, in relation to organisms in the aquatic ecosystem was studied. With the help of ecotoxicity data, a preliminary environmental risk assessment of PFA, PAA and ClO2 for CSO disinfection...... of PFA, PAA and ClO2, a minimum dilution factor (590 times for PFA, 138 times for PAA and 700 times for ClO2) is needed for discharge into the surface water, to avoid the risk of toxic effect in the aquatic environment, albeit the rapid degradation of PFA and ClO2 in water will not have an acute toxic...... for a preliminary risk assessment of disinfectants entering the aquatic ecosystem in the receiving water’s post-disinfection discharge. Performic acid (PFA) and peracetic acid (PAA) are used to disinfect CSO water, in order to reduce the number of indicator bacteria. Moreover, PFA and PAA do not form toxic by...

  18. Effects of a behavior change campaign on household drinking water disinfection in the Lake Chad basin using the RANAS approach.

    Science.gov (United States)

    Lilje, Jonathan; Mosler, Hans-Joachim

    2018-04-01

    Worldwide, an estimated 700 million people rely on unimproved drinking water sources; even more consume water that is not safe to drink. Inadequate drinking water quality constitutes a major risk factor for cholera and other diarrheal diseases around the globe, especially for young children in developing countries. Household water treatment and safe storage systems represent an intermediate solution for settings that lack infrastructure supplying safe drinking water. However, the correct and consistent usage of such treatment technologies rely almost exclusively on the consumer's behavior. This study targeted at evaluating effects of a behavior change campaign promoting the uptake of household drinking water chlorination in communities along the Chari and Logone rivers in Chad. The campaign was based on formative research using health psychological theory and targeted several behavioral factors identified as relevant. A total of 220 primary caregivers were interviewed concerning their household water treatment practices and mindset related to water treatment six months after the campaign. The Risks, Attitudes, Norms, Abilities, and Self-regulation (RANAS) model was used to structure the interviews as the RANAS approach had been used for designing the campaign. Results show significantly higher self-reported drinking water chlorination among participants of the intervention. Significant differences from a control group were identified regarding several behavioral factors. Mediation analysis revealed that the intervention positively affected participants' individual risk estimation for diarrheal disease, health knowledge, perceived efforts and benefits of water treatment, social support strategies, knowledge of how to perform chlorination, and perceived ability to do so. The campaign's effect on water treatment was mainly mediated through differences in health knowledge, changes in norms, and self-efficacy convictions. The findings imply that water treatment behavior

  19. High compliance randomized controlled field trial of solar disinfection of drinking water and its impact on childhood diarrhea in rural Cambodia

    CSIR Research Space (South Africa)

    McGuigan, KG

    2011-09-01

    Full Text Available Recent solar disinfection (SODIS) studies in Bolivia and South Africa have reported compliance rates below 35% resulting in no overall statistically significant benefit associated with disease rates. In this study, the authors report the results...

  20. To add or not to add: the use of quenching agents for the analysis of disinfection by-products in water samples.

    Science.gov (United States)

    Kristiana, Ina; Lethorn, Arron; Joll, Cynthia; Heitz, Anna

    2014-08-01

    The formation of disinfection by-products (DBPs) is a public health concern due to their potential adverse health effects. Robust and sensitive methods for the analysis of DBPs, as well as appropriate sample handling procedures, are essential to obtain accurate, precise and reliable data on DBP occurrence and formation. In particular, the use of an appropriate quenching agent is critical to prevent further formation of DBPs during the holding time between sample collection and analysis. Despite reports of decomposition of DBPs caused by some quenching agents, particularly sulphite and thiosulphate, a survey of the literature shows that they are still the most commonly used quenching agents in analysis of DBPs. This study investigated the effects of five quenching agents (sodium sulphite, sodium arsenite, sodium borohydride, ascorbic acid, and ammonium chloride) on the stability of seven different classes of DBPs commonly found in drinking waters, in order to determine the most appropriate quenching agent for the different classes of DBPs. All of the quenching agents tested did not adversely affect the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs), and thus are suitable for quenching of disinfectant residual prior to analysis of these DBPs. Ascorbic acid was found to be suitable for the analysis of haloacetonitriles (HANs) and haloketones (HKs), but should not be used for the analysis of chlorite. Sodium arsenite, sodium borohydride, and ascorbic acid were all acceptable for the analysis of haloacetaldehydes (HALs). All of the quenching agents tested adversely affected the concentration of chloropicrin. A 'universal' quenching agent, suitable for all groups of DBPs studied, was not identified. However, based on the results of this study, we recommend the use of ascorbic acid for quenching of samples to be analysed for organic DBPs (i.e. THMs, HAAs, HANs, HKs, and HALs) and sodium sulphite for analysis of inorganic DBPs. Our study is the first

  1. Performance of Ag-TiO2 Photocatalysts towards the Photocatalytic Disinfection of Water under Interior-Lighting and Solar-Simulated Light Irradiations

    Directory of Open Access Journals (Sweden)

    Camilo A. Castro

    2012-01-01

    Full Text Available This paper reports the characterization and photoactivity of Ag-TiO2 materials using different amounts of silver during the hydrothermal synthesis. Photocatalysts were characterized by means of TEM, XPS, XRD, DRS, and N2 sorption isotherms to determine the textural properties. The photocatalyst's configuration was observed to be as anatase-brookite mixed phase particles with Ag partially oxidized aggregates on the TiO2 surface, which increased visible light absorption of the material. Moreover, photoproduction of singlet oxygen was followed by EPR analysis under visible light irradiations following the formation of TEMPOL. Such photoproduction was totally decreased by using the singlet oxygen scavenger DABCO. Photocatalysts were tested towards the photocatalytic disinfection of water suing a solar light simulator and an interior-light irradiation setup. Results evidenced an increase in the photooxidative effect of TiO2, while dark processes evidenced that part of the inactivation process is due to the Ag-TiO2 surface bactericidal effect and possible lixiviated Ag+.

  2. Effectiveness of solar disinfection using batch reactors with non-imaging aluminium reflectors under real conditions: Natural well-water and solar light.

    Science.gov (United States)

    Navntoft, C; Ubomba-Jaswa, E; McGuigan, K G; Fernández-Ibáñez, P

    2008-12-11

    Inactivation kinetics are reported for suspensions of Escherichia coli in well-water using compound parabolic collector (CPC) mirrors to enhance the efficiency of solar disinfection (SODIS) for batch reactors under real, solar radiation (cloudy and cloudless) conditions. On clear days, the system with CPC reflectors achieved complete inactivation (more than 5-log unit reduction in bacterial population to below the detection limit of 4CFU/mL) one hour sooner than the system fitted with no CPC. On cloudy days, only systems fitted with CPCs achieved complete inactivation. Degradation of the mirrors under field conditions was also evaluated. The reflectivity of CPC systems that had been in use outdoors for at least 3 years deteriorated in a non-homogeneous fashion. Reflectivity values for these older systems were found to vary between 27% and 72% compared to uniform values of 87% for new CPC systems. The use of CPC has been proven to be a good technological enhancement to inactivate bacteria under real conditions in clear and cloudy days. A comparison between enhancing optics and thermal effect is also discussed.

  3. Removal of Disinfection By-Products from Contaminated Water Using a Synthetic Goethite Catalyst via Catalytic Ozonation and a Biofiltration System

    Directory of Open Access Journals (Sweden)

    Yu-Hsiang Wang

    2014-09-01

    Full Text Available The effects of synthetic goethite (α-FeOOH used as the catalyst in catalytic ozonation for the degradation of disinfection by-product (DBP precursors are investigated. A biofiltration column applied following the catalytic ozonation process is used to evaluate the efficiency of removing DBP precursors via biotreatment. Ozone can rapidly react with aromatic compounds and oxidize organic compounds, resulting in a decrease in the fluorescence intensity of dissolved organic matter (DOM. In addition, catalytic ozonation can break down large organic molecules, which causes a blue shift in the emission-excitation matrix spectra. Water treated with catalytic ozonation is composed of low-molecular structures, including soluble microbial products (SMPs and other aromatic proteins (APs. The DOM in SMPs and APs is removed by subsequent biofiltration. Catalytic ozonation has a higher removal efficiency for dissolved organic carbon and higher ultraviolet absorbance at 254 nm compared to those of ozonation without a catalyst. The use of catalytic ozonation and subsequent biofiltration leads to a lower DBP formation potential during chlorination compared to that obtained using ozonation and catalytic ozonation alone. Regarding DBP species during chlorination, the bromine incorporation factor (BIF of trihalomethanes and haloacetic acids increases with increasing catalyst dosage in catalytic ozonation. Moreover, the highest BIF is obtained for catalytic ozonation and subsequent biofiltration.

  4. Inactivation modeling of human enteric virus surrogates, MS2, Qβ, and ΦX174, in water using UVC-LEDs, a novel disinfecting system.

    Science.gov (United States)

    Kim, Do-Kyun; Kim, Soo-Ji; Kang, Dong-Hyun

    2017-01-01

    In order to assure the microbial safety of drinking water, UVC-LED treatment has emerged as a possible technology to replace the use of conventional low pressure (LP) mercury vapor UV lamps. In this investigation, inactivation of Human Enteric Virus (HuEV) surrogates with UVC-LEDs was investigated in a water disinfection system, and kinetic model equations were applied to depict the surviving infectivities of the viruses. MS2, Qβ, and ΦX 174 bacteriophages were inoculated into sterile distilled water (DW) and irradiated with UVC-LED printed circuit boards (PCBs) (266nm and 279nm) or conventional LP lamps. Infectivities of bacteriophages were effectively reduced by up to 7-log after 9mJ/cm2 treatment for MS2 and Qβ, and 1mJ/cm2 for ΦX 174. UVC-LEDs showed a superior viral inactivation effect compared to conventional LP lamps at the same dose (1mJ/cm2). Non-log linear plot patterns were observed, so that Weibull, Biphasic, Log linear-tail, and Weibull-tail model equations were used to fit the virus survival curves. For MS2 and Qβ, Weibull and Biphasic models fit well with R2 values approximately equal to 0.97-0.99, and the Weibull-tail equation accurately described survival of ΦX 174. The level of UV-susceptibility among coliphages measured by the inactivation rate constant, k, was statistically different (ΦX 174 (ssDNA)>MS2, Qβ (ssRNA)), and indicated that sensitivity to UV was attributed to viral genetic material. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Environmental cleaning and disinfection.

    Science.gov (United States)

    Traverse, Michelle; Aceto, Helen

    2015-03-01

    The guidelines in this article provide veterinarians, veterinary technicians, and veterinary health care workers with an overview of evidence-based recommendations for the best practices associated with environmental cleaning and disinfection of a veterinary clinic that deals with small animals. Hospital-associated infections and the control and prevention programs necessary to alleviate them are addressed from an environmental perspective. Measures of hospital cleaning and disinfection include understanding mechanisms and types of contamination in veterinary settings, recognizing areas of potential concern, addressing appropriate decontamination techniques and selection of disinfectants, the management of potentially contaminated equipment, laundry, and waste management, and environmental surveillance strategies. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Humidifier disinfectants, unfinished stories

    Directory of Open Access Journals (Sweden)

    Yeyong Choi

    2016-02-01

    Full Text Available Once released into the air, humidifier disinfectants became tiny nano-size particles, and resulted in chemical bronchoalveolitis. Families had lost their most beloved members, and even some of them became broken. Based on an estimate of two million potential victims who had experienced adverse effects from the use of humidifier disinfectants, we can say that what we have observed was only the tip of the iceberg. Problems of entire airways, as well as other systemic effects, should be examined, as we know these nano-size particles can irritate cell membranes and migrate into systemic circulation. The story of humidifier disinfectant is not finished yet.

  7. Activity and action screening of selected disinfectants

    Directory of Open Access Journals (Sweden)

    Kateřina Balharová

    2006-01-01

    Full Text Available This research work is aimed to monitoring of selected disinfectants´activity in operational conditions. Hereby there have been monitored two acidic disinfectants Despon K and Mikasan D, which have had-by their producer-stated different recommended concentration. These solutions were monitored in viewpoint of their activity at different temperature, time of circulation, pH and water hardness. In this work there were measured pH of solutions in unloaded medium to be compared with pH of solutions in loaded medium and this measuring was carried out regularly each week within a one month period. During this period there was also monitored total plate count (TPC, which was stated in the dairy, where samples were taken two-times monthly. It has been found, that the disinfectants Mikasan D and Mikal 94D are effective even by high water hardness.

  8. Disinfection of laryngoscopes: A survey of practice

    Directory of Open Access Journals (Sweden)

    Vaishali Prabhakar Chaskar

    2017-01-01

    Full Text Available Background and Aims: The laryngoscope is a common piece of equipment used by anaesthesiologists. It has been identified as a potential source of cross infection. Although guidelines exist regarding appropriate disinfection practices, recent reviews suggest ineffectiveness of current methods of disinfection and poor compliance with the established protocols. We conducted a questionnaire-based survey to study the current disinfection practices being followed by a cross section of anaesthesiologists. Methods: A simple questionnaire containing 13 questions was distributed amongst anaesthesiologists in an anaesthesia conference. Data were analysed with percentage analysis. Results: Out of 250 delegates who attended the conference, 150 submitted the completed questionnaires. Residents constituted 41% and 46% were consultants. Eighteen (12% used only tap water for cleaning and 132 (88% used a chemical agent after rinsing with water. Out of 132, 76 (51% used detergent/soap solution, 29 (19% would wash and then soak in disinfectant or germicidal agents (glutaraldehyde, povidone iodine and chlorhexidine and 18 (12% would wipe the blade with an alcohol swab. With respect to disinfection of laryngoscope handles, 70% respondents said they used an alcohol swab, 18% did not use any method, 9% were not aware of the method being used, while 3% did not respond. Conclusion: Our results indicate wide variation in methods of decontamination of laryngoscopes. Awareness regarding laryngoscope as a potential source of infection was high. We need to standardise and implement guidelines on a national level and make available resources which will help to improve patient safety.

  9. La desinfección-antisepsia y esterilización en la atención primaria de salud: Laboratorios Desinfection-antisepsis and sterilization in primay health care: Laboratories

    Directory of Open Access Journals (Sweden)

    Abilio Ubaldo Rodríguez Pérez

    2006-09-01

    Full Text Available La desinfección-antisepsia y esterilización son procedimientos que se utilizan como elementos de ruptura de la cadena de transmisión de microorganismos, evitando posibles contaminaciones a nivel de laboratorios para el nivel primario de asistencia médica, por lo que es nuestro objetivo describirlos en el presente trabajo y establecer una política en este sentido.Desinfection-antisepsis and sterilization are procedures that are used as elements to break up the microorganisms transmission chain, preventing possible contaminations in the laboratories at the primary health care level. It is our objective to describe them and to establish a policy in this sense.

  10. Formation of bromate and halogenated disinfection byproducts during chlorination of bromide-containing waters in the presence of dissolved organic matter and CuO

    KAUST Repository

    Liu, Chao

    2015-12-02

    Previous studies showed that significant bromate (BrO3-) can be formed via the CuO-catalyzed disproportionation of hypobromous acid (HOBr) pathway. In this study, the influence of CuO on the formation of BrO3- and halogenated disinfection byproducts (DBPs) (e.g., trihalomethanes, THMs and haloacetic acids, HAAs) during chlorination of six dissolved organic matter (DOM) isolates was investigated. Only in the presence of slow reacting DOM (from treated Colorado River water, i.e., CRW-BF-HPO), significant BrO3- formation is observed, which competes with bromination of DOM (i.e., THM and HAA formation). Reactions between HOBr and 12 model compounds in the presence of CuO indicates that CuO-catalyzed HOBr disproportionation is completely inhibited by fast reacting phenols, while it predominates in the presence of practically unreactive compounds (acetone, butanol, propionic, and butyric acids). In the presence of slow reacting di- and tri-carboxylic acids (oxalic, malonic, succinic, and citric acids), BrO3- formation varies, depending on its competition with bromoform and dibromoacetic acid formation (i.e., bromination pathway). The latter pathway can be enhanced by CuO due to the activation of HOBr. Therefore, increasing CuO dose (0-0.2 g L-1) in a reaction system containing chlorine, bromide, and CRW-BF-HPO enhances the formation of BrO3-, total THMs and HAAs. Factors including pH and initial reactant concentrations influence the DBP formation. These novel findings have implications for elevated DBP formation during transportation of chlorinated waters in copper-containing distribution systems.

  11. Evaluating dissolved organic carbon-water partitioning using polyparameter linear free energy relationships: Implications for the fate of disinfection by-products.

    Science.gov (United States)

    Neale, Peta A; Escher, Beate I; Goss, Kai-Uwe; Endo, Satoshi

    2012-07-01

    The partitioning of micropollutants to dissolved organic carbon (DOC) can influence their toxicity, degradation, and transport in aquatic systems. In this study carbon-normalized DOC-water partition coefficients (K(DOC-w)) were measured for a range of non-polar and polar compounds with Suwannee River fulvic acid (FA) using headspace and solid-phase microextraction (SPME) methods. The studied chemicals were selected to represent a range of properties including van der Waal forces, cavity formation and hydrogen bonding interactions. The K(DOC-w) values were used to calibrate a polyparameter linear free energy relationship (pp-LFER). The difference between experimental and pp-LFER calculated K(DOC-w) values was generally less than 0.3 log units, indicating that the calibrated pp-LFER could provide a good indication of micropollutant interaction with FA, though statistical analysis suggested that more data would improve the predictive capacity of the model. A pp-LFER was also calibrated for Aldrich humic acid (HA) using K(DOC-w) values collected from the literature. Both experimental and pp-LFER calculated K(DOC-w) values for Aldrich HA were around one order of magnitude greater than Suwannee River FA. This difference can be explained by the higher cavity formation energy in Suwannee River FA. Experimental and pp-LFER calculated K(DOC-w) values were compared for halogenated alkanes and alkenes, including trihalomethane disinfection by-products, with good agreement between the two approaches. Experimental and calculated values show that DOC-water partitioning is generally low; indicating that sorption to DOC is not an important fate process for these chemicals in the environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Solar disinfection (SODIS): simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti.

    Science.gov (United States)

    Oates, Peter M; Shanahan, Peter; Polz, Martin F

    2003-01-01

    Haiti and other developing countries do not have sufficient meteorological data to evaluate if they meet the solar disinfection (SODIS) threshold of 3-5 h of solar radiation above 500 W/m2, which is required for adequate microbial inactivation in drinking water. We have developed a mathematical model based on satellite-derived daily total energies to simulate monthly mean, minimum, and maximum 5-h averaged peak solar radiation intensities. This model can be used to assess if SODIS technology would be applicable anywhere in the world. Field measurements were made in Haiti during January 2001 to evaluate the model and test SODIS efficacy as a point-of-use treatment option. Using the total energy from a measured solar radiation intensity profile, the model recreated the intensity profile with 99% agreement. NASA satellite data were then used to simulate the mean, minimum, and maximum 5-h averaged peak intensities for Haiti in January, which were within 98.5%, 62.5%, and 86.0% agreement with the measured values, respectively. Most of the discrepancy was attributed to the heterogeneous nature of Haiti's terrain and the spatial resolution of the NASA data. Additional model simulations suggest that SODIS should be effective year-round in Haiti. Actual SODIS efficacy in January was tested by the inactivation of total coliform, E. coli, and H2S-producing bacteria. Exposure period proved critical. One-day exposure achieved complete bacterial inactivation 52% of the time, while a 2-day exposure period achieved complete microbial inactivation 100% of the time. A practical way of providing people with cold water every morning that has undergone a 2-day exposure would be to rotate three groups of bottles every morning, so two groups are out in the sun and one is being used for consumption.

  13. Randomized intervention study of solar disinfection of drinking water in the prevention of dysentery in Kenyan children aged under 5 years.

    Science.gov (United States)

    du Preez, Martella; Conroy, Ronan M; Ligondo, Sophie; Hennessy, James; Elmore-Meegan, Michael; Soita, Allan; McGuigan, Kevin G

    2011-11-01

    We report the results of a randomized controlled intervention study (September 2007 to March 2009) investigating the effect of solar disinfection (SODIS) of drinking water on the incidence of dysentery, nondysentery diarrhea, and anthropometric measurements of height and weight among children of age 6 months to 5 years living in peri-urban and rural communities in Nakuru, Kenya. We compared 555 children in 404 households using SODIS with 534 children in 361 households with no intervention. Dysentery was recorded using a pictorial diary. Incidence rate ratios (IRR) for both number of days and episodes of dysentery and nondysentery diarrhea were significantly (P SODIS, corresponding to an average of 0.8 cm over a 1-year period over the group as a whole (95% CI 0.7 to 1.6 cm, P = 0.031). Median weight-for-age was higher in those on SODIS, corresponding to a 0.23 kg difference in weight over the same period; however, the confidence interval spanned zero and the effect fell short of statistical significance (95% CI -0.02 to 0.47 kg, P = 0.068). SODIS and control households did not differ in the microbial quality of their untreated household water over the follow-up period (P = 0.119), but E. coli concentrations in SODIS bottles were significantly lower than those in storage containers over all follow-up visits (P SODIS on childhood anthropometry, compared with children in the control group and should alleviate concerns expressed by some commentators that the lower rates of dysentery associated with SODIS are the product of biased reporting rather than reflective of genuinely decreased incidence.

  14. Killing of Gyrodactylus salaris by heat and chemical disinfection.

    Science.gov (United States)

    Koski, Perttu; Anttila, Pasi; Kuusela, Jussi

    2016-03-23

    Gyrodactylus salaris is a monogenean, which has collapsed tens of wild Atlantic salmon populations. One of the means of preventing the spread of the parasite is the disinfection of the fishing equipment, which is used in the rivers having susceptible salmon populations. Little is known about the dosage of disinfectants against G. salaris. There are not standards for the testing of disinfectants against multicellular parasites. The present investigation developed a method to test disinfectants and examined the effectiveness of heated water and a commercially available disinfectant (Virkon S) in killing G. salaris. Individual G. salaris worms were followed under the microscope during treatment with heated water or Virkon S disinfectant blend. The logarithm of the time needed to kill the parasite was used as a dependent variable in linear regression. The upper 99.98 % prediction line for the dependent variable was used to obtain a value resembling the time needed for a 4 log reduction of the microbial pathogen, which is commonly used as a criterion for disinfectants. Also 6 log reduction was applied. Exposure to a relatively low temperature was found to kill the parasite. Even 5-50 min treatment (=10-100 times the 99.98 % upper prediction value) with heated water at 40 °C might be used. This would enable the utilisation of hot tap water in the disinfection of fishing gear. The present practice of 1 % Virkon S for 15 min was also found to kill the parasite. The follow-up of single parasites of a test population and the use of the calculated upper predictive line in the regression analysis offers a method to analyse the effects of disinfectants on parasites like G. salaris. The results of our tests give possibilities for using disinfection methods, which may be more acceptable by the fishermen than the present ones.

  15. Chloramines in Drinking Water

    Science.gov (United States)

    Chloramines are disinfectants used to treat drinking water. Chloramines are most commonly formed when ammonia is added to chlorine to treat drinking water. Chloramines provide longer-lasting disinfection as the water moves through pipes to consumers.

  16. Inactivation of bacterial contaminants in drinking water using a novel batch-process TiO2-assisted solar photocatalytic disinfection (SPC-DIS) reactor for use in developing countries

    Energy Technology Data Exchange (ETDEWEB)

    McGuigan, K. G.; Duffy, E. F.; Al Touati, F.; Kehoe, S. C.; McLoughlin, O. A.; Gill, L. W.; Gernjak, W.; Oller, I.; Maldonado, M. I.; Malato, S.; Reed, R. H.

    2004-07-01

    The technical feasibility and performance of photocatalytic TiO2 coatings in batch-process solar disinfection (SODIS) reactors to improve potability of drinking water in developing countries have been studied. Borosilicate glass and PET plastic SODIS reactor fitted with flexible plastic inserts coated with TiO2 powder were shown to be 20% and 25% more effective, respectively, than standard SODIS reactors for the inactivation of E. coli K12 . Approximately 550J is required per litre of water to produce each 1-long-unit reduction in bacterial population within SPC-DIS reactors of the design described in this study. (Author) 14 refs.

  17. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Rodríguez-Martínez, Sarah; Puertas-Bennasar, Antoni; Araujo, Rosa M.

    2015-01-01

    Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed. PMID:26241039

  18. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella.

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Rodríguez-Martínez, Sarah; Puertas-Bennasar, Antoni; Araujo, Rosa M

    2015-01-01

    Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed.

  19. The efficacy of potassium ferrate as a chemical disinfectant on E. coli, Vibrio cholera, human adenovirus, and Giardia lamblia - Abstract

    Science.gov (United States)

    Introduction: Drinking water and wastewater effluents go through numerous treatments to remove microorganisms and other contaminants in the United States. One of many processes along the treatment train is disinfection, and to date the most common disinfectants still remain chemi...

  20. In vitro adhesion of Acanthamoeba castellanii to soft contact lenses depends on water content and disinfection procedure.

    Science.gov (United States)

    Reverey, Julia F; Fromme, Roland; Leippe, Matthias; Selhuber-Unkel, Christine

    2014-08-01

    To compare the potential of different soft contact lenses to be contaminated with Acanthamoeba castellanii as a function of material parameters and cleaning procedures. Different unworn soft hydrogel and silicone hydrogel contact lenses were incubated with human pathogenic A. castellanii. The adhesion of the acanthamoebae was investigated on the contact lenses and put into relation to their material parameters. The efficacy of a recommended contact lens cleaning procedure in reducing A. castellanii adhesion was investigated. We found that material parameters such as elastic modulus, silicone content, ionic properties and swelling do not influence the adhesion of acanthamoebae to soft contact lenses. A material parameter that influenced adhesion significantly was the water content of the lens. With increasing water content, the adhesion of acanthamoebae increased. By following the cleaning instructions of the manufacturer the contamination of the lenses with A. castellanii could be reduced to a minimum, as shown both on contact lenses and in control experiments. With this study we show that for the tested lenses, the adhesion of A. castellanii to contact lenses is independent of the silicone content of the lens, but depends nonlinearly on the water content of the lens. Furthermore, we demonstrate that applying proper lens cleaning procedures minimizes the risk of acanthamoebae adhesion to contact lenses. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  1. Microbial contamination and disinfection methods of pacifiers

    Science.gov (United States)

    NELSON, Paulo; LOUVAIN, Márcia Costa; MACARI, Soraia; LUCISANO, Marília Pacífico; da SILVA, Raquel Assed Bezerra; de QUEIROZ, Alexandra Mussolino; GATON-HERNÁNDEZ, Patrícia; da SILVA, Léa Assed Bezerra

    2015-01-01

    Objectives To evaluate the microbial contamination of pacifiers by Mutans Streptococci (MS) and the efficacy of different methods for their disinfection. Methods Twenty-eight children were assigned to a 4-stage changeover system with a 1-week interval. In each stage, children received a new pacifier and the parents were instructed to maintain their normal habits for 1 week. After this time, the pacifiers were subjected to the following 4 disinfection methods: spraying with 0.12% chlorhexidine solution, Brushtox® or sterile tap water, and immersion in boiling tap water for 15 minutes. Microbiological culture for MS and Scanning Electron Microscopy (SEM) were performed. The results were analyzed statistically by Friedman’s non-parametric test (a=0.05). Results The 0.12% chlorhexidine spray was statistically similar to the boiling water (p>0.05) and more effective than the Brushtox® spray and control (p<0.05). The analysis of SEM showed the formation of a cariogenic biofilm in all groups with positive culture. Conclusions Pacifiers become contaminated by MS after their use by children and should be disinfected routinely. Spraying with a 0.12% chlorhexidine solution and immersion in boiling water promoted better disinfection of the pacifiers compared with a commercial antiseptic toothbrush cleanser (Brushtox®). PMID:26537723

  2. Effective household disinfection methods of kitchen sponges

    Science.gov (United States)

    Several household disinfecting treatments to kill bacteria, yeasts and molds on kitchen sponges were evaluated. Sponges were soaked in 10 percent bleach for 3 min, lemon juice (pH 2.9) or deionized water for 1 min; placed in a microwave oven for 1 min; or placed in a dishwasher operating with a dryi...

  3. Effects of biofilm formation on haemodialysis monitor disinfection.

    Science.gov (United States)

    Cappelli, Gianni; Sereni, Luisa; Scialoja, Maria Grazia; Morselli, Massimo; Perrone, Salvatore; Ciuffreda, Angela; Bellesia, Massimo; Inguaggiato, Paola; Albertazzi, Alberto; Tetta, Ciro

    2003-10-01

    Biofilms are composed of communities of micro-organisms adhering to essentially any surface. We evaluated whether biofilm formation in the hydraulic circuit of a purposely contaminated haemodialysis monitor would modify the efficacy of different disinfection modalities against bacteria and endotoxin concentrations. A water-borne Pseudomonas aeruginosa (109) suspension was recirculated for 1 h and was left standing for 72 h (stationary phase) in the hydraulic circuit of the monitor. The monitor was then washed and disinfected by different physical (heat, 85 degrees C) or chemical (hypochlorite or peracetic acid) disinfection modalities (protocol A). In protocol B, the bacterial suspension was also recirculated for 1 h, but the monitor was then immediately washed and disinfected by different chemical disinfection modalities (hypochlorite or peracetic acid). Biofilm formation was revealed by scanning and confocal laser electron microscopy after the stationary phase (protocol A), but was absent when the monitor was immediately washed and disinfected (protocol B). In the presence of biofilm (protocol A), heat in association with citric acid was the most effective modality for reducing both colony forming units and endotoxin concentrations, whereas heat by itself was the least effective method of disinfection. Dwelling (60 h) with diluted peracetic acid completely prevented the formation of biofilm. In the absence of biofilm (protocol B), chemical disinfection proved to be effective against both colony forming units and endotoxin concentrations. We found that biofilm formation may markedly reduce the efficacy of presently available disinfection modalities. Therefore, different disinfection modalities and the combined action of descaling (by citric acid) and disinfection (physical/chemical agents) should be used periodically in haemodialysis monitors. In addition, dwelling with diluted peracetic acid should be adopted whenever monitors are not in use.

  4. Effects of different cavity‑disinfectants and potassium titanyl ...

    African Journals Online (AJOL)

    disinfectants and potassium titanyl phosphate (KTP) laser on microtensile bond strength to primary dentin. Chlorhexidine (CHX), propolis (PRO), ozonated water (OW), gaseous ozone (OG) and KTP laser were used for this purpose. Methodology: ...

  5. Disinfection by-products and their precursors in a water treatment plant in North China: Seasonal changes and fraction analysis.

    Science.gov (United States)

    Chen, Chao; Zhang, Xiao-Jian; Zhu, Ling-Xia; Liu, Jing; He, Wen-Jie; Han, Hong-da

    2008-07-01

    A one-year-long monitoring project was conducted to assay the concentrations of THMs, HAAs and their formation potential along the conventional process in a water treatment plant in North China. Subsequent investigations of organic matter fractionation and the contribution of the algae to the precursor were also conducted to trace the source of the DBPs. The results showed that the concentration of DBPs and their formation potential varied with the seasons. The highest concentrations of THMs and the highest HAAs formation potential, each almost 500 microg/L, were detected in autumn and the lowest were in spring, no more than 100 microg/L. Both organic matter and algae were found to be important DBP precursors. The hydrophobic acid fraction in dissolved organic matter has the highest formation potential for both THM and HAA. Algae contribute about 20% to 50% of the total formation potential during an algal bloom. The efficiency of each unit process for DBPs and precursors was also assayed. Unfortunately, the conventional drinking water treatment process is limited in its efficiency for precursor removal. The pre-chlorination and filtration process had a negative effect on DBP or precursor removal.

  6. New Water Disinfectant: an Insoluble Quaternary Ammonium Resin-Triiodide Combination that Releases Bactericide on Demand 1

    Science.gov (United States)

    Taylor, S. L.; Fina, L. R.; Lambert, J. L.

    1970-01-01

    Strongly basic anion-exchange resins form stable, water-insoluble combinations with triiodide ions. The combinations have remarkable antibacterial properties: 3.0 × 105Escherichia coli cells per ml were killed when passed through a 3.8-g column of commercially available resin treated with triiodide (volume 4 ml after treatment). In an attempt to deplete the resin-triiodide complex, 1.14 × 109E. coli cells in 15 liters were passed through the column with no significant loss of effectiveness. The antibacterial capabilities of the resin-triiodide columns ranged from 106Salmonella typhimurium per ml to 1.1 × 104Streptococcus faecalis per ml. Staphylococcus aureus and Pseudomonas aeruginosa were also tested and killed at concentrations of 1.8 × 104 and 1.3 × 105 per ml, respectively. The cells were not filtered from the water. They emerged from the column in nonviable form. This was demonstrated by using 14C-labeled bacteria. The irreversible nature of the antibacterial action was revealed when attempts to wash the damaged cells did not restore viability. PMID:4991917

  7. THE POWER TO DETECT A DIFFERENCE: DETERMINING SAMPLE SIZE REQUIREMENTS FOR EVALUATION OF REPRODUCTIVE/DEVELOPMENTAL EFFECTS FROM EXPOSURE TO COMPLEX MIXTURES OF DISINFECTION BYPRODUCTS

    Science.gov (United States)

    Toxicological assessment of environmentally-realistic complex mixtures of drinking-water disinfection byproducts (DBPs) are needed to address concerns raised by some epidemiological studies showing associations between exposure to chemically disinfected water and adverse reproduc...

  8. Disinfection for infection prevention over the course of time

    Science.gov (United States)

    Hell, M.; Pauser, G.

    2007-01-01

    In recent years and decades increasingly more emphasis has been placed on alcohol-based solutions for hygienic and surgical hand disinfection. Traditional handwashing with soap and water has been largely replaced in the everyday clinical setting, as has the use of disinfectant soap-based solutions for surgical hand disinfection. It has been possible in recent years to reduce the exposure time for alcohol-based hand disinfection in surgery from 5 to 3 minutes, and there are plans to reduce this even further. The growing awareness of the tolerability issues has also given rise to favorable developments here. There have also been dramatic changes in preoperative skin disinfection. The non-alcoholic solutions with a slow onset of action (e.g. iodophors) have been virtually replaced by alcohol-based solutions of demonstrated efficacy. Non-alcoholic solutions continue to be used for disinfection of mucous membranes, but iodine-based products are being phased out here. The term “instrument disinfection” has been largely supplanted now by the expression “instrument reprocessing or medical device decontamination” (which is also underpinned by legislation) and it takes account of the trend towards thermal disinfection. Meticulous cleaning is thus an indispensable precondition for sterilization, which normally follows disinfection. The greatest lack of consensus at European level relates to surface