WorldWideScience

Sample records for aeration

  1. Solar powered dugout aeration

    International Nuclear Information System (INIS)

    Pasture dugouts are a significant source of water for livestock on the Canadian Prairies and as such, must maintain the best water quality possible. Aeration improves the water quality and is part of a good management plan to reduce overall water treatment costs. Although dugouts can be aerated naturally through wind and wave action and photosynthesis, this generally aerates only the top portion of the dugout. Artificial aeration by air injection into the lowest point of the dugout ensures that the water is oxygenated throughout the entire dugout. Solar aeration can be used in remote areas where grid power is not practical. With solar powered aeration systems, solar panels are used to generate the electrical power needed to run the compressor while storing excess energy in batteries. A solar aeration system includes solar panels, deep cycle batteries to store excess power, a control board with a regulator, a compressor, a weighed feeder hose, and an air diffuser. This publication presented the design of a solar aeration system and its cost. 1 tab., 3 figs

  2. Aerator Placement Strategies

    Science.gov (United States)

    The purpose of this study was to determine the effects on fish production, water quality and economics of concentrating paddlewheel aeration in large commercial ponds, compared to the current method of aerator placement. Ten 17-acre ponds (approximately 600 X 1300 ft) were brought into the study in ...

  3. Catfish production using intensive aeration

    Science.gov (United States)

    For the last 3 years, researchers at UAPB and NWAC have been monitoring and verifying production yields in intensively aerated catfish ponds with aeration rates greater than 6 hp/acre. We now have three years of data on commercial catfish production in intensively aerated ponds. With stocking densi...

  4. Aeration equipment for small depths

    Science.gov (United States)

    Sluše, Jan; Pochylý, František

    2015-05-01

    Deficit of air in water causes complications with cyanobacteria mainly in the summer months. Cyanobacteria is a bacteria that produces poison called cyanotoxin. When the concentration of cyanobacteria increases, the phenomena "algal bloom" appears, which is very toxic and may kill all the organisms. This article describes new equipment for aeration of water in dams, ponds and reservoirs with small depth. This equipment is mobile and it is able to work without any human factor because its control is provided by a GPS module. The main part of this equipment consists of a floating pump which pumps water from the surface. Another important part of this equipment is an aerator where water and air are blended. Final aeration process runs in the nozzles which provide movement of all this equipment and aeration of the water. Simulations of the flow are solved by multiphase flow with diffusion in open source program called OpenFOAM. Results will be verified by an experiment.

  5. Deflector plants turbine aeration

    International Nuclear Information System (INIS)

    Water quality requirements have become a focal point in recent re-licensing of hydroelectric projects. The Federal Energy Regulatory Commission has significantly increased the relevance of license conditions to insure that turbine discharges meet state or other specific criteria for dissolved oxygen (D.O.). Due to naturally occurring depletion of D.O. at increased depths in large reservoirs, water withdrawn from this strata may result in unacceptably low levels of D.O. Different researchers have evaluated various methods of improving D.O. content in hydro turbine discharges, including; diffusers, weirs, oxygen injection, and variations of turbine venting. The authors describe an approach called deflector plate turbine aeration. This computer based, engineered approach allows systems to be evaluated, designed, and installed with predictable performance and costs. Many experts in this field now agree that, to the extent practical, turbine venting offers the most dependable, maintenance free, and cost effective solution to the low D.O. problem. The approach presented in this paper has resulted in proven results

  6. Cavity length below chute aerators

    Institute of Scientific and Technical Information of China (English)

    WU JianHua; RUAN ShiPing

    2008-01-01

    It is proved that air entrainment is one of the efficient measures dealing with cavitation control for the release works of hydropower projects. There are many factors to be considered in designing a chute aerator. One of the most important factors concerns the cavity length below the aerator, which has outstanding effects on air entrainment against cavitation damage. It is crucial to determine reasonable emergence angle for the calculation of the cavity length. In the present paper the overall effects of structural and hydraulic parameters on the emergence angle of the flow from the aerator were analyzed. Four improved expressions of the emergence angle with weight coefficient were investigated through experimental data of 68 points observed from 12 aerators of 6 hydropower projects, of both model and prototype, on the basis of error theory. A method to calculate the cavity length below aerators was suggested, which considers overall effects of the above mentioned parameters. Comparison between the method in this paper and the other five methods of calculating the cavity length showed that the present method is much more reliable than the existing methods while the mean error of the method is less than others.

  7. Cavity length below chute aerators

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is proved that air entrainment is one of the efficient measures dealing with cavi-tation control for the release works of hydropower projects. There are many factors to be considered in designing a chute aerator. One of the most important factors concerns the cavity length below the aerator,which has outstanding effects on air entrainment against cavitation damage. It is crucial to determine reasonable emergence angle for the calculation of the cavity length. In the present paper the overall effects of structural and hydraulic parameters on the emergence angle of the flow from the aerator were analyzed. Four improved expressions of the emer-gence angle with weight coefficient were investigated through experimental data of 68 points observed from 12 aerators of 6 hydropower projects,of both model and prototype,on the basis of error theory. A method to calculate the cavity length be-low aerators was suggested,which considers overall effects of the above men-tioned parameters. Comparison between the method in this paper and the other five methods of calculating the cavity length showed that the present method is much more reliable than the existing methods while the mean error of the method is less than others.

  8. AERATION OF THE ICE-COVERED WATER POOLS USING THE WAVE FLOW AERATOR

    OpenAIRE

    Solomin E.E; Sirotkin E.A.; SolominE.V.

    2013-01-01

    This article describes the technical advantages and economic benefits of the ice-covered pool aeration plants consuming power from renewable energy sources. We made a comparative evaluation of the wave flow-aeration method and other methods of pool aeration. We showed the indexes and the characteristics of the wave flow-maker for aeration of ice-covered pools on the territory of Russia. We also made calculations of the economic benefits of aeration plants using the devices converting renewabl...

  9. Who's working on fishpond aeration

    OpenAIRE

    Kibria, S.

    1991-01-01

    The findings are provided of a literature search conducted on the topic of fishpond aeration, using ASFA for the period 1971-1990 and the ICLARM library and professional staff collection. A total of 97 articles were found. The type of publication is indicated and details given of some of the recent publications and some research institutions working in this field.

  10. Aeration equipment for small depths

    Directory of Open Access Journals (Sweden)

    Sluše Jan

    2015-01-01

    Full Text Available Deficit of air in water causes complications with cyanobacteria mainly in the summer months. Cyanobacteria is a bacteria that produces poison called cyanotoxin. When the concentration of cyanobacteria increases, the phenomena „algal bloom“ appears, which is very toxic and may kill all the organisms. This article describes new equipment for aeration of water in dams, ponds and reservoirs with small depth. This equipment is mobile and it is able to work without any human factor because its control is provided by a GPS module. The main part of this equipment consists of a floating pump which pumps water from the surface. Another important part of this equipment is an aerator where water and air are blended. Final aeration process runs in the nozzles which provide movement of all this equipment and aeration of the water. Simulations of the flow are solved by multiphase flow with diffusion in open source program called OpenFOAM. Results will be verified by an experiment.

  11. Research on the Effectiveness of Aerators

    Directory of Open Access Journals (Sweden)

    Vytenis Leonavičius

    2013-02-01

    Full Text Available In biological wastewater treatment plants, the right selection of an aerator is one of the most important elements. The choice of the aerator must take in account its performance – dissolved oxygen content per unit of energy consumed, oxidative capacity and supply of the required amount of air so that the required concentration of oxygen is saturated properly. The experiments have been conducted carefully examining the efficiency of the selected deep–cavitation aerator operating without the aerator tip or with attached two and three–blade tips. The performed investigation included air dispersion methods of opposite ejecting for determining air flow, flow pressure and dependence of vibration on different placement of the aerator under varying positions of corners. It has been established that compared to air ejecting flow, changes in pressure and vibration are most significantly influenced by a deep–cavitation aerator having a three–blade tip.Article in Lithuanian

  12. Research on the Effectiveness of Aerators

    Directory of Open Access Journals (Sweden)

    Vytenis Leonavičius

    2012-12-01

    Full Text Available In biological wastewater treatment plants, the right selection of an aerator is one of the most important elements. The choice of the aerator must take in account its performance – dissolved oxygen content per unit of energy consumed, oxidative capacity and supply of the required amount of air so that the required concentration of oxygen is saturated properly. The experiments have been conducted carefully examining the efficiency of the selected deep–cavitation aerator operating without the aerator tip or with attached two and three–blade tips. The performed investigation included air dispersion methods of opposite ejecting for determining air flow, flow pressure and dependence of vibration on different placement of the aerator under varying positions of corners. It has been established that compared to air ejecting flow, changes in pressure and vibration are most significantly influenced by a deep–cavitation aerator having a three–blade tip.Article in Lithuanian

  13. Intermittent Aeration in Biological Treatment of Wastewater

    Directory of Open Access Journals (Sweden)

    H. Doan

    2009-01-01

    Full Text Available Problem statement: E-coating process is widely used to provide a protective coating layer on metal parts in the automotive and metal finishing industry. The wastewater from the coating process contains organic compounds that are used in the cleaning, pretreatment and coating steps. Organic pollutants can be removed biologically. In the aerobic biological treatment, water aeration accounts for a significant portion of the total operating cost of the treatment process. Intermittent aeration is thus of benefit since it would reduce the energy consumption in the wastewater treatment. In the present study, wastewater from an electro-coating process was treated biologically using a packed column as an aerator where the wastewater was aerated by a countercurrent air flow. The objective was to obtain an optimum aeration cycle. Approach: Intermittent aeration time was varied at different preset cycles. An operational optimum of the aeration time (or air-water contacting time in the column was determined from the BOD5 removal after a certain treatment period. For continuous aeration of the wastewater, the air-liquid contacting time in the column was 52 min for 24 h of treatment. A unit energy consumption for pumping liquid and air, which was defined as the energy consumption per percent BOD5 removed, was used as a criterion to determine the optimum contacting time. Results: Optimum air-liquid contacting times were found to be about 38, 26 and 22 min for the treatment times of 24, 48 and 72 h, consecutively. This indicates that 27-58% saving on the unit energy consumption can be achieved using intermittent aeration of the wastewater. On the basis of the overall BOD5 removal, 17% and 23% savings in energy were observed with the intermittent aeration as compared to the continuous aeration of the wastewater for 48 and 72 h. Conclusion: The results obtained indicate that an appropriate intermittent aeration cycle can bring about a substantial energy saving

  14. COMPUTER AIDED DESIGN OF DIFFUSED AERATION SYSTEMS

    Science.gov (United States)

    CADDAS (Computer Aided Design of Diffused Aeration Systems) is a microcomputer-based program that analyzes the cost and performance of diffused aeration used in activated sludge wastewater treatment systems. The program can analyze both coarse bubble and fine pore diffusers as we...

  15. Penetration height correlations for non-aerated and aerated transverse liquid jets in supersonic cross flow

    Energy Technology Data Exchange (ETDEWEB)

    Ghenai, Chaouki [Florida Atlantic University, Department of Mechanical Engineering, College of Engineering and Computer Science, Boca Raton, FL (United States); Sapmaz, Hayri [Boston Scientific, Miami, FL (United States); Lin, Cheng-Xian [University of Tennessee, Department of Mechanical, Aerospace, and Biomedical Engineering, Knoxville, TN (United States)

    2009-01-15

    Experimental results on the mixing of non-aerated and aerated transverse liquid jet in supersonic cross flow (M=1.5) are presented in this paper. The goal of this study is to investigate the effect of the gas/liquid mass ratio on the penetration and atomization of an aerated liquid jet in high speed cross flow and to develop correlations for the penetration heights. High speed imaging system was used in this study for the visualization of the injection of aerated liquid jet. The results show the effect of jet/cross flow momentum flux ratio, the gas/liquid mass ratio and the Ohnesorge number on the penetration of aerated liquid jet in supersonic cross-flow. New correlations of the spray penetration height for the non-aerated liquid jet (GLR=0) and the net gain in spray penetration height for the aerated liquid jet (GLR>0) are presented. (orig.)

  16. ASPECTS REGARDING THE METHODS OF SOIL AERATION

    OpenAIRE

    A. UNGURAŞU; A. UNGUREANU

    2011-01-01

    Aspects regarding the methods of soil aeration. Soil aeration is a process to be carried out continuously the gas exchange between soil and atmosphere. The process is done mainly by the movement of water inside and outside him. There are three major gases in the soil (nitrogen,oxygen and carbon dioxide). Soil air composition differs from that of air by higher CO2 content (0,3 to 0,5%). The air in the soil is very important for the dynamics of soil. Soil aeration is accomplished through mass f...

  17. Effect of Aeration on Seafood Processing Wastewater

    OpenAIRE

    Neena Sunny; Jinu John

    2014-01-01

    The main environmental problems of fish industries are high water consumption and high organic matter, oil and grease, ammonia, nitrogen and salt contents in the waste water. Aeration helps in the oxidation of these minerals. This paper consequently focuses on how the various constituents of waste water vary with aeration. Diffused fine bubble aeration was done in a circular tank at various flow rates (3 l/minute,6.2 l/minute.6.4l/minute) at a constant time period of 20 hours ...

  18. HYDRAULIC RESEARCH OF AERATORS ON TUNNEL SPILLWAYS

    Institute of Scientific and Technical Information of China (English)

    RUAN Shi-ping; WU Jian-hua; WU Wei-wei; XI Ru-ze

    2007-01-01

    The selection of the configuration and size of an aerator was of importance for a tunnel spillway under the conditions of high speed flows. Experimental investigations were conducted on the effects of entrained air on the tunnel spillway in the Goupitan Project, based on the criterion of gravity similarity and the condition of aerated flow velocity of over 6 m/s, with physical models. The configurations of the aerators were presented of a larger bottom air concentration, to protect the tunnel spillway from cavitation as well as to see no water fills in the grooves.

  19. The Influence of Aerator Mounting and Wastewater Treatment Plant Design on the Performance of Aeration Systems

    OpenAIRE

    Ala Sokolova; Mindaugas Rimeika

    2011-01-01

    The paper analyzes the impact of the way of mounting a tube diffuser, the design of an aeration tank and the presence of a fixed carrier on the operational parameters of aeration systems used in small wastewater treatment plants. It was found out that the vertically mounted tube diffuser decreased standard oxygen transfer rate (SOTR) of the aeration system by approximately 20% and standard oxygen transfer efficiency (SOTE) by 25% comparing to the horizontally mounted tube diffuser. It was als...

  20. DESIGN MANUAL: FINE PORE AERATION SYSTEMS

    Science.gov (United States)

    This manual presents the best current practices for selecting, designing, operating, maintaining, and controlling fine pore aeration systems used in the treatment of municipal wastewater. It was prepared by the American Society of Civil Engineers Committee on Oxygen Transfer unde...

  1. EMERGENCE ANGLE OF FLOW OVER AN AERATOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aerator is an important device for release works of hydraulic structures with high-speed flow in order to protect them from cavitation damage. This kind of protecting effect is related closely to cavity length below the aerator, while the cavity length is dominated by the emergence angle over the aerator. Therefore it is crucial to determine this angle accurately. In the present paper the affecting intensities of flow depth and the fluctuating velocity on this angle were analyzed through two introduced parameters. Furthermore, the improved expressions of emergence angle estimation, for both ramp-type and step-type aerators, were presented by means of 68 sets of experimental data from 6 projects based on error theory. The results showed that the present method has higher accuracy than the previously reported methods.

  2. T.A. BROWN MECHANICAL AERATOR

    Science.gov (United States)

    Students in the Environmental Engineering and Waster Resources capstone design class in the Department of Civil and Environmental Engineering will undertake a project in conjunction with Serasih Indonesia to develop a prototype mechanical aerator to be used in aquaculture live...

  3. Intermittent Aeration in Biological Treatment of Wastewater

    OpenAIRE

    Doan, H.; Lohi, A.

    2009-01-01

    Problem statement: E-coating process is widely used to provide a protective coating layer on metal parts in the automotive and metal finishing industry. The wastewater from the coating process contains organic compounds that are used in the cleaning, pretreatment and coating steps. Organic pollutants can be removed biologically. In the aerobic biological treatment, water aeration accounts for a significant portion of the total operating cost of the treatment process. Intermittent aeration is ...

  4. AERATION OF THE ICE-COVERED WATER POOLS USING THE WAVE FLOW AERATOR

    Directory of Open Access Journals (Sweden)

    Solomin E.E

    2013-12-01

    Full Text Available This article describes the technical advantages and economic benefits of the ice-covered pool aeration plants consuming power from renewable energy sources. We made a comparative evaluation of the wave flow-aeration method and other methods of pool aeration. We showed the indexes and the characteristics of the wave flow-maker for aeration of ice-covered pools on the territory of Russia. We also made calculations of the economic benefits of aeration plants using the devices converting renewable energy. The project can be scaled and extended to the territory of the CIS, Europe, USA and Canada in the changing climate conditions and the variety of feed reservoirs around the world.

  5. Effects of aeration on gamma irradiation of sewage sludge

    International Nuclear Information System (INIS)

    In this paper the effect of aeration on gamma irradiation of sewage sludge was investigated to examine the potential solubilization of solids in sewage sludge to ultimately reduce the solids volume for disposal. Results showed that aeration increased the effectiveness of gamma radiation. The efficiency of sludge solubilization with aeration was increased by around 25% compared to that without aeration at an irradiation dose of 2.5-9 kGy. The soluble protein, polysaccharide and humic (like) substance concentrations were higher under aerated conditions. With aeration the overall reaction appears to be oxidative as evidenced by the higher nitrate and nitrite ion concentrations in solution.

  6. Effects of aeration on gamma irradiation of sewage sludge

    Science.gov (United States)

    Chu, Libing; Wang, Jianlong; Wang, Bo

    2010-08-01

    In this paper the effect of aeration on gamma irradiation of sewage sludge was investigated to examine the potential solubilization of solids in sewage sludge to ultimately reduce the solids volume for disposal. Results showed that aeration increased the effectiveness of gamma radiation. The efficiency of sludge solubilization with aeration was increased by around 25% compared to that without aeration at an irradiation dose of 2.5-9 kGy. The soluble protein, polysaccharide and humic (like) substance concentrations were higher under aerated conditions. With aeration the overall reaction appears to be oxidative as evidenced by the higher nitrate and nitrite ion concentrations in solution.

  7. Effect of Aeration on Seafood Processing Wastewater

    Directory of Open Access Journals (Sweden)

    Neena Sunny

    2014-04-01

    Full Text Available The main environmental problems of fish industries are high water consumption and high organic matter, oil and grease, ammonia, nitrogen and salt contents in the waste water. Aeration helps in the oxidation of these minerals. This paper consequently focuses on how the various constituents of waste water vary with aeration. Diffused fine bubble aeration was done in a circular tank at various flow rates (3 l/minute,6.2 l/minute.6.4l/minute at a constant time period of 20 hours using air stones and the percentage reduction in ammonia, total Kjeldahl nitrogen , BOD,COD and salts were found out . It was found that as flow rate of aeration increase the percentage removal of above constituents also increased. Optimum removal was possible at a flow rate of 6.4l/min. BOD, COD, Ammoniacal nitrogen, Kjeldahl nitrogen, were found to be removed by 91.2%, 82.79%,57.76%, 90.6% respectively . Aeration had no effect on salts and lipids .

  8. Sawdust discharge rate from aerated hoppers

    Institute of Scientific and Technical Information of China (English)

    Pan Chen; Zhulin Yuan; Chien-Song Chyang; Fu-Xiong Zhuan

    2011-01-01

    This paper presents a numerical and experimental study of the discharge rate of sawdust from an aerated hopper as an important parameter in many industrial processes involving the handling of other granular materials. Numerical experiments are conducted by means of an Eulerian-Eulerian approach coupled with the kinetic theory of granular flow (KTGF). Emphasis is given to the effects of particle size, hopper outlet width, hopper half angle, aeration height and air flow rate. The results show that the discharge rate is significantly affected by hopper outlet width, particle size and air flow rate, but is not sensitive to the hopper half angle and aeration height: increasing hopper outlet width or air flow rate increases discharge rate, while increasing particle size decreases discharge rate. Close agreement between numerical predictions and experimental results is obtained.

  9. FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

    Institute of Scientific and Technical Information of China (English)

    MA Fei; WU Jian-hua

    2012-01-01

    The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control.Based on the theoretical considerations,the experiments of the aerator for a discharge tunnel were conducted,and the relationships between the flow regime and hydraulic and geometric parameters were investigated.The results showed that,there are two kinds of threshold values for the flow regime conversions.One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity,and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity.Two empirical expressions were obtained for the conversions of the flow regimes,which can be used in the designs of the aerators.

  10. The Influence of Aerator Mounting and Wastewater Treatment Plant Design on the Performance of Aeration Systems

    Directory of Open Access Journals (Sweden)

    Ala Sokolova

    2011-02-01

    Full Text Available The paper analyzes the impact of the way of mounting a tube diffuser, the design of an aeration tank and the presence of a fixed carrier on the operational parameters of aeration systems used in small wastewater treatment plants. It was found out that the vertically mounted tube diffuser decreased standard oxygen transfer rate (SOTR of the aeration system by approximately 20% and standard oxygen transfer efficiency (SOTE by 25% comparing to the horizontally mounted tube diffuser. It was also defined that the design of the aeration tank might have an impact on the operation parameters of the aeration system: when the centre shell used to protect a diffuser was dismantled from a test tank, SOTR and SOTE increased by approximately 20%. It was also established that the presence of the fixed carrier in the aeration tank did not have an impact on the performance of aeration systems. Finally, research was carried out to compare the operational parameters of two diffusers of different types offered on the market and used in small wastewater treatment plants. It was found out that the performance different type diffusers  might vary considerably.Article in Lithuanian

  11. PRESSURE CHARACTERISTICS OF CAVITATION CONTROL BY AERATION

    Institute of Scientific and Technical Information of China (English)

    DONG Zhi-yong; LU Yang-quan; JU Wen-jie; CAI Xin-ming; DING Chun-sheng

    2005-01-01

    This experimental investigation was systematically conducted with the aid of a non-circulating water tunnel in the Hydraulics Laboratory at Zhejiang University of Technology in China.The test velocity is between 20m/s and 40m/s.The least air concentration to prevent cavitation erosion lies between 1.7% and 4.5%.Pressure waveforms with and without aeration in cavitation and cavitation erosion regions were measured.Time-averaged pressure profiles with and without aeration were compared.Pressure characteristics corresponding to least air concentration to prevent cavitation erosion in cavitation and cavitation erosion regions were analyzed.

  12. Acid mine water aeration and treatment system

    Science.gov (United States)

    Ackman, Terry E.; Place, John M.

    1987-01-01

    An in-line system is provided for treating acid mine drainage which basically comprises the combination of a jet pump (or pumps) and a static mixer. The jet pump entrains air into the acid waste water using a Venturi effect so as to provide aeration of the waste water while further aeration is provided by the helical vanes of the static mixer. A neutralizing agent is injected into the suction chamber of the jet pump and the static mixer is formed by plural sections offset by 90 degrees.

  13. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

    Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat...

  14. Soil Aeration Variability as Affected by Reoxidation

    Institute of Scientific and Technical Information of China (English)

    A.WOLI(N)SKA; Z.ST(E)PNIEWSKA

    2013-01-01

    The interplay between soil physical parameters during the recovery from anoxic stresses (reoxidation) is largely unrecognized.This study was conducted to characterise the soil aeration status and derive correlations between variable aeration factors during reoxidation.Surface layers (0-30 cm) of three soil types,Haplic Phaeozem,Mollic Gleysol,and Eutric Cambisol (FAO soil group),were selected for analysis.The moisture content was determined for a range of pF values (0,1.5,2.2,2.7,and 3.2),corresponding to the available water for microorganisms and plant roots.The variability of a number of soil aeration parameters,such as water potential (pF),air-filled porosity (Eg),oxygen diffusion rate (ODR),and redox potential (Eh),were investigated.These parameters were found to be interrelated in most cases.There were significant (P < 0.001) negative correlations of pF,Eg,and ODR with Eh.A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment.These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.

  15. Evaluation of oxygen transfer parameters of fine-bubble aeration system in plug flow aeration tank of wastewater treatment plant

    Institute of Scientific and Technical Information of China (English)

    Xiaohong Zhou; Yuanyuan Wu; Hanchang Shi; Yanqing Song

    2013-01-01

    Knowledge of the oxygen mass transfer of aerators under operational conditions in a full-scale wastewater treatment plant (WWTP) is meaningful for the optimization of WWTP,however,scarce to best of our knowledge.Through analyzing a plug flow aeration tank in the Lucun WWTP,in Wuxi,China,the oxygenation capacity of fine-bubble aerators under process conditions have been measured insitu using the off-gas method and the non-steady-state method.The off-gas method demonstrated that the aerators in different corridors in the aeration tank of WWTP had significantly different oxygen transfer performance; furthermore,the aerators in the same corridor shared almost equal oxygen transfer performance over the course of a day.Results measured by the two methods showed that the oxygen transfer performance of fine-bubble aerators in the aeration tank decreased dramatically compared with that in the clean water.The loss of oxygen transfer coefficient was over 50% under low-aeration conditions (aeration amount < 0.67 Nm3/hr).However,as the aeration amount reached 0.96 Nm3/hr,the discrepancy of oxygen transfer between the process condition and clean water was negligible.The analysis also indicated that the non-steady-state and off-gas methods resulted in comparable estimates of oxygen transfer parameters for the aerators under process conditions.

  16. Development of a water purification system via enhanced aeration 1. Phenomenological characteristics of the aeration system

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, M.; Nonaka, M. [Tokyo Univ. (Japan)

    1998-07-25

    An enormous number of industrial and municipal waste materials should directly and indirectly enhance the environmental pollution in rivers, lakes and reservoirs. The change of the human life style is also another important factor affecting on the pollution of water environments. One of the most effective and economical ways to conserve, improve and purity the water environment should be the enhancement of the dissolved oxygen concentration by aeration. In this study, an enhanced aeration system is developed to cope with low efficiency, scale-up difficulty and restricted versatility accompanied with conventional aeration systems. The developed aeration system utilizes the centrifugal shear stress to generate an enormous number of fine air bubbles and to establish the high propagation performance of mixing energy. The pressure loss of the cyclone-like aerator is deduced from the dimensional analysis and experimental works, which serves to scale up the aeration system and to evaluate the energy consumption of the whole system. 14 refs., 10 figs., 1 tab.

  17. Landfill aeration worldwide: Concepts, indications and findings

    International Nuclear Information System (INIS)

    Highlights: ► Different landfill aeration concepts and accordant application areas are described. ► Examples of full scale projects are provided for Europe, North-America and Asia. ► Major project findings are summarised, including prospects and limitations. ► Inconsistencies between laboratory and full scale results have been elaborated. ► An explanatory approach in connection with the inconsistencies is provided. - Abstract: The creation of sustainable landfills is a fundamental goal in waste management worldwide. In this connection landfill aeration contributes towards an accelerated, controlled and sustainable conversion of conventional anaerobic landfills into a biological stabilized state associated with a minimised emission potential. The technology has been successfully applied to landfills in Europe, North America and Asia, following different strategies depending on the geographical region, the specific legislation and the available financial resources. Furthermore, methodologies for the incorporation of landfill aeration into the carbon trade mechanisms have been developed in recent years. This manuscript gives an overview on existing concepts for landfill aeration; their application ranges and specifications. For all of the described concepts examples from different countries worldwide are provided, including details regarding their potentials and limitations. Some of the most important findings from these aeration projects are summarised and future research needs have been identified. It becomes apparent that there is a great demand for a systematisation of the available results and implications in order to further develop and optimise this very promising technology. The IWWG (International Waste Working Group) Task Group “Landfill Aeration” contributes towards the achievement of this goal.

  18. Radon in water aeration system operational performance

    International Nuclear Information System (INIS)

    North East Environmental Products, Inc. is a manufacturer of residential scale aeration systems for removal of radon and volatile organic chemicals from private water supplies. This paper is a review of the operational history of residential scale point of entry (POE) radon aeration systems. Emphasis is placed on the difficulties and solutions encountered in actual installations caused by both mechanical difficulties and water quality parameters. A summary of radon reduction efficiency is presented for wells with radon concentrations from 21,000 to 2,600,000 pCi/L. A discussion of customer concerns and attitudes is presented along with other areas for further technical improvement. Training techniques for dealers and installers are also discussed. An update of the current status of the radon in water industry includes current sales volumes as compared to the potential market and an update on the radon in water MCL standard setting process from an industry perspective

  19. CFD model of an aerating hydrofoil

    International Nuclear Information System (INIS)

    Improving water quality in the tailrace below hydroelectric dams has become a priority in many river systems. In warm climates, water drawn by the turbine from deep in a reservoir can be deficient in dissolved oxygen (DO), a critical element in maintaining a healthy aquatic ecosystem. Many different solutions have been proposed in order to increase the DO levels in turbine discharge, including: turbine aeration systems (adding air to the water through either the turbine hub, the periphery or through distributed aeration in the runner blades); bubble diffusers in the reservoir or in the tailrace; aerating weirs downstream of the dams; and surface water pumps in the reservoir near the dam. There is a significant potential to increase the effectiveness of these solutions by improving the way that oxygen is introduced into the water; better distributions of bubbles will result in better oxygen transfer. In the present study, a two-phase Computational Fluid Dynamics model has been formulated using a commercial code to study the distribution of air downstream of a simple aerating hydrofoil. The two-phase model uses the Eulerian-Eulerian approach. Appropriate relations are used to model the interphase forces, including the Grace drag force model, the Favre averaged drag force and the Sato enhanced eddy viscosity. The model is validated using experimental results obtained in the water tunnel at the University of Minnesota's Saint Anthony Falls Laboratory. Results are obtained for water velocities between 5 and 10 m/s, air flow rates between 0.5 and 1.5 sL/min and for angles of attack between 0° and -8°. The results of this study show that the CFD model provides a good qualitative comparison to the experimental results by well predicting the wake location at the different flow rates and angles of attack used

  20. Aeration and hydrodynamics in submerged membrane bioreactors

    OpenAIRE

    Braak, Etienne; Alliet-Gaubert, Marion; Schetrite, Sylvie; Albasi, Claire

    2011-01-01

    Membrane bioreactor (MBR) is already a well-developed wastewater treatment process for both municipal and industrial applications. Nonetheless, membrane fouling remains a significant problem for its wider development. In the case of submerged membrane bioreactors (SMBRs), one of the most efficient strategies to limit fouling is the use of a gas/liquid two-phase flow to enhance the mass transfer. However, the effect of aeration still remains incompletely understood. The complexity ...

  1. Cavity filling water control below aerator devices

    Institute of Scientific and Technical Information of China (English)

    钱尚拓; 吴建华; 马飞; 徐建荣; 彭育; 汪振

    2014-01-01

    With the rapid development of high dam projects within China, the dragon-drop-tail spillway tunnel is introduced and widely used. In view of the high water head and the large flow velocity on the dragon-drop-tail section, aerator devices are usually placed for the cavitation damage control. For the device placed in its initial position, it is a serious concern to design a suitable flow regime of the cavity and to control the cavity filling water due to the large flow depth and the low Froude number through this aera-tor. In this study, the relationships between the geometries of the aerator device and the jet impact angle of the lower trajectory of the flow are theoretically analyzed with/without a local slope. Nine test cases with different geometries are designed, the effectiveness of the filling water control is experimentally investigated under different operation conditions, and two criteria of the local slope design are proposed. It is concluded that the cavity flow regime and the filling water can be improved if a small impact angle and some sui-table geometries of the local slope are designed.

  2. Inverse problem of bottom slope design for aerator devices

    Institute of Scientific and Technical Information of China (English)

    吴建华; 樊博; 许唯临

    2013-01-01

    Air entrainment is an effective approach to protect release works from cavitation damage. The traditional method of aera-tor device designs is that, for given flow conditions, the geometries of the aerator device are designed and then the effects are experi-mentally tested for cavitation damage control. The present paper proposes an inverse problem method of determining the bottom slopes in front of and behind an aerator if the requirements of air entrainment, flow conditions and some of aerator geometric para-meters are given. An RBF neural network model is developed and the relevant bottom slopes are calculated in different conditions of flow and geometry on the basis of the data of 19 aerator devices from different discharge tunnels with safe operation. The case study shows that the methodology provides an effective way to design aerator devices under given target conditions.

  3. Oxidation of magnetite in aerated aqueous media

    International Nuclear Information System (INIS)

    Metastable equilibria involving phases less stable than hematite can be significantly more oxidizing than the calculated equilibrium between well-crystallized hematite and magnetite. In this report, generalized solubility and stability relationships between magnetite and Fe2O3.xH2O phases are derived to describe the metastable equilibria. Experiments with synthetic magnetite powders in aerated aqueous solutions show that crystalline hematite is formed within days at temperatures above 100 C in pure water or solutions containing anions (e.g., Cl-, SO42-, HCO3-) that do not form very strong surface complexes with iron oxides. In the presence of dissolved phosphate or silica, however, the dissolution-precipitation route to hematite is strongly inhibited, and maghemite is a persistent metastable product. Thus, phosphate or silica are expected to delay the approach to magnetite-hematite equilibrium in aerated groundwaters conditioned by magnetite. These findings are presented in the context of nuclear fuel waste disposal. (author). 63 refs., 1 tab., 11 figs

  4. HYDRODYNAMICS INfluence on oxidative capacity of AERATION BASIN

    OpenAIRE

    Kulkov Viktor Nikolaevich; Solopanov Evgenij Jurjevich

    2012-01-01

    The velocity fields of water flow to the impact on the hydrodynamic conditions in the aeration basin by the guide plate. It is shown that one can optimize the hydrodynamics of the aeration basin in order to increase its oxidative capacity.

  5. Composting paper mill deinking sludge with forced aeration

    Energy Technology Data Exchange (ETDEWEB)

    Brouillette, M.; Trepanier, L.; Gallichand, J.; Beauchamp, C. [Laval Univ., Quebec City, PQ (Canada)

    1996-04-01

    A composting strategy to dispose of deinking sludge was discussed. Deinking sludge is a waste by-product containing mainly paper fibres, clay particles and ink. Composting with forced aeration can reduce the volume and stabilize the sludge so it may be economically used in agricultural, landscaping and horticultural applications. In this study, static pile forced aeration was used as an alternative to mechanical pile turning. Two piles of 2 to 3 metres in height were used with three aeration pipes of different aeration levels. Results showed that 3 metre piles required longer aeration times to maintain temperatures in the required range of 50-65 degrees C. Water content remained within 60-71% for optimum composting. Fibre levels decreased gradually during the experiment, with cellulose being the most degraded. Aeration improved micro organic activity; organic nitrogen was also higher in aerated treatments. It was concluded that composting of deinking sludge with forced aeration is feasible in northeastern Canada even with outside temperatures as low as -20 degrees C. 20 refs., 4 tabs., 8 figs.

  6. OXIDATION OF AS(III) BY AERATION AND STORAGE

    Science.gov (United States)

    A study of the effects of aeration and storage on the oxidation of arsenic(III) was undertaken at three utilities in the US to establish the engineering significance of aeration as a potential pre-treatment method for arsenic removal. The results of this study clearly establish t...

  7. Aeration for the removal of Rn from small water supplies

    International Nuclear Information System (INIS)

    Aeration is an emerging technology for the removal of radon from small public and private water supplies. It offers advantages over granular activated carbon (GAC) by avoiding the retention of radon progeny which causes an elevated gamma exposure rate and a potential for low level radioactive waste generation. A new diffused bubble aeration technology also offers advantages over packed tower aeration in terms of economics, performance, and aesthetics. This paper reports on recent field data from twenty prototype diffused bubble aeration systems located in six northeastern states. Theoretical and actual performance will be discussed for flows ranging from point-of-entry (POE) up to 400 gpm. The technology is capable of removing greater than 99.9 percent of the raw water radon from these supplies. Removal is greater than that achieved with GAC or packed tower aeration

  8. EFFECT OF AERATOR ON HYDRAULIC DRAG ACTING ON A CHUTE

    Institute of Scientific and Technical Information of China (English)

    NI Han-gen; LI Xin; ZHOU Jing; JIN Qiao

    2005-01-01

    The formulae used to calculate the friction in the non-uniform flow chute were examined with the experimental data, and the results show that the accuracy of the formula is enough for engineering applications. A comparison between the results of friction respectively from the uniform flow assumption and the non-uniform flow approximation indicates that the former is an order of magnitude larger than the latter in the case of steep chute. The hydraulic drag on a steep chute with aerators was measured on the hydraulic model directly and the coefficient of the aerator effect on the drag was obtained. The variation patterns of the wall shear just downstream of the aerators were investigated and the mechanism of the increase in the drag by aerator were analyzed qualitatively with the measured water-depths just downstream the aerators.

  9. Two-phase flow simulation of aeration on stepped spillway

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiangju; LUO Lin; ZHAO Wenqian; LI Ran

    2004-01-01

    Stepped spillways have existed as escape works for a very long time. It is found that water can trap a lot of air when passing through steps and then increasing oxygen content in water body, so stepped spillways can be used as a measure of re-aeration and to improve water quality of water body. However, there is no reliable theoretical method on quantitative calculation of re-aeration ability for the stepped spillways. By introducing an air-water two-phase flow model, this paper used k-ε turbulence model to calculate the characteristic variables of free-surface aeration on stepped spillway. The calculated results fit with the experimental results well. It supports that the numerical modeling method is reasonable and offers firm foundation on calculating re-aeration ability of stepped spillways. The simulation approach can provide a possible optimization tool for designing stepped spillways of more efficient aeration capability.

  10. Interaction between afternoon aeration and tilapia stocking density

    OpenAIRE

    Francisco Roberto dos Santos Lima; Davi de Holanda Cavalcante; Vanessa Tomaz Rebouças; Marcelo Vinícius do Carmo e Sá

    2016-01-01

    The present study aimed at determining the effects of the interaction between afternoon aeration and stocking density of Nile tilapia on variables of water and soil quality, growth performance and effluent quality. The experiment was a 3 x 2 factorial randomized block design, with three stocking densities (8, 12 and 16 fish per tank or 43.5, 65.3, and 87.0 g m-3) under two mechanical aeration regimes, absence (control; three replicates) and afternoon aeration (four replicates). The afternoon ...

  11. Research on Aeration Systems Efficiency in Small Wastewater Treatment Plants

    OpenAIRE

    Ala Sokolova

    2011-01-01

    Large amount of small wastewater treatment plants does not work properly. One of the reasons could be wrong design of the aeration system. Therefore, the aim of this research is to analyse the performance of two aeration systems used in Lithuanian small wastewater treatment plants. Both aeration systems are designed for the following parameters: 4 PE and 0,8 m3/d wastewater flow. These data correspond to the oxygen requirement of 40,9 g O2/h. Summarizing the results of the research, it was fo...

  12. Feasibility of automatic aeration for insect pest management for rice stored in East Texas

    Science.gov (United States)

    Aeration using automatic controllers was compared with manually-activated aeration (manual aeration) in bins of farm-stored rice in Nome, TX, from 17 September 2002 through the end of the year. Manual aeration was defined as the farm owner activating the fans manually in mid-October, while automati...

  13. Comparison of Energy Dissipation with and without Aerators

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Experimental results showed that aerators increase the energy dissipation of the flow in the channel by reducing the velocity coefficient φ in the deflector bucket and the jet-trajectory length, by increasing energy dissipation of the jet flow in the air and the diffusion length of the jet falling into the pool and by reducing the energy intensity of the jet falling into the pool. The energy dissipation prevents wash out downstream.When air is not entrained in the water flow, the aerators act as artificial irregularities in the channel. The energy dissipation due to the aerators in the channel without entrained air is greater than when air is entrained in the water flow.Correlations of the experimental data can be used to estimate the energy dissipation effect of the aerators on the outlet structure for the three test cases.

  14. EVALUATION OF AERATION/CIRCULATION AS A LAKE RESTORATION TECHNIQUE

    Science.gov (United States)

    Artificial circulation and hypolimnetic aeration are management techniques for oxygenating eutrophic lakes subject to water quality problems, algal blooms, and fishkills. Artificial circulation is achieved by injecting diffused air into lower waters, by mechanial pumping of water...

  15. Generating CO2-credits through landfill in situ aeration

    International Nuclear Information System (INIS)

    Landfills are some of the major anthropogenic sources of methane emissions worldwide. The installation and operation of gas extraction systems for many landfills in Europe and the US, often including technical installations for energy recovery, significantly reduced these emissions during the last decades. Residual landfill gas, however, is still continuously produced after the energy recovery became economically unattractive, thus resulting in ongoing methane emissions for many years. By landfill in situ aeration these methane emissions can be widely avoided both, during the aeration process as well as in the subsequent aftercare period. Based on model calculations and online monitoring data the amount of avoided CO2-eq. can be determined. For an in situ aerated landfill in northern Germany, acting as a case study, 83-95% (depending on the kind and quality of top cover) of the greenhouse gas emission potential could be reduced under strictly controlled conditions. Recently the United Nations Framework Convention on Climate Change (UNFCCC) has approved a new methodology on the 'Avoidance of landfill gas emissions by in situ aeration of landfills' (). Based on this methodology landfill aeration projects might be considered for generation of Certified Emission Reductions (CERs) in the course of CDM projects. This paper contributes towards an evaluation of the potential of landfill aeration for methane emissions reduction.

  16. CAVITATION CONTROL BY AERATION AND ITS COMPRESSIBLE CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    DONG Zhi-yong; SU Pei-lan

    2006-01-01

    This paper presents an experimental investigation and a theoretical analysis of cavitation control by aeration and its compressible characteristics at the flow velocity V=20m/s-50m/s. Pressure waveforms with and without aeration in cavitation region were measured. The variation of compression ratio with air concentration was described, and the relation between the least air concentration to prevent cavitation erosion and flow velocity proposed based on our experimental study. The experimental results show that aeration remarkably increases the pressure in cavitation region, and the corresponding pressure wave exhibits a compression wave/shock wave. The pressure increase in cavitation region of high-velocity flow with aeration is due to the fact that the compression waves/shock wave after the flow is aerated. The compression ratio increases with air concentration rising. The relation between flow velocity and least air concentration to prevent cavitation erosion follows a semi-cubical parabola. Also, the speed of sound and Mach number of high-velocity aerated flow were analyzed.

  17. Effect of aeration on fast gas pressure tests

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-jia; JIANG Cheng-lin; LI Xiao-wei; TANG Jun; WANG Chen; YANG Fei-long; WANG Fa-kai; ZHANG Chao-jie; DENG Shu-hua

    2009-01-01

    Given the problem of the long time required for testing gas pressure, we propose a fast-test method in which we used a technique of fast borehole sealing and air replenishing. Based on the characteristics of gas emission from boreholes to be tested, we built a theoretical model for calculating parameters during the process of increasing natural pressure and aeration. Using this model, we investigated the effect of different aeration conditions on velocity of pressure tests. The result shows that: 1) aerating air into boreholes can speed up gas pressure tests and 2) the more similar the pressure of the aerated air to the original gas pressure, the smaller the gas volume absorbed by coal and the shorter the time needed in pressure test. A case study in the Lu'an mining area shows that the time needed for gas pressure test is only 4 h using our method of aeration and 29 h under conditions of increasing natural pressure, saving time by 86.2%. This case study also indicates that, by using the aeration method, only one hour is needed for gas pressure to reach a stable state, which breaks the record of the shortest time needed for gas pressure tests in China.

  18. Winery Wastewater Treatment Applying Aerated Submerged

    Directory of Open Access Journals (Sweden)

    Alessandra Pellizzaro Bento

    2010-06-01

    Full Text Available The winery wastewater usually shows conditions of low pH, high organic loads and concentrations of carbon, nitrogen and phosphorus that are inappropriate for biologic treatment. The purpose of this research was to apply the technology of aerated submerged biofilter (ASB for the winery effluent treatment during the harvest (ASB 1 and non harvest (ASB 2 at lab scale. Therefore, two up flow biofilter built on glass (5 liters volume were installed. The nutrient balance of the winery wastewater was adjusted and the correction of the pH was done by oyster shell used as filter material. The efficiency removal (COD for the harvest reactor was 90% while for the non harvest was 82%. The oyster shells contributed to an increase on average of 180 mg/L of alkalinity to the BAS 1 and 318 mg/L for the BAS 2. As regards the metals, the average values in the treated effluent to meet iron and zinc is permitted by the environmental standards of Santa Catarina. Under the experimental conditions applied in this research, this kind of reactor has presented potential for the treatment of winery wastewater. However, operational improvements would be required in the reactors to adequate them to the specific management into the wineries.

  19. A new step aeration approach towards the improvement of nitrogen removal in a full scale Carrousel oxidation ditch.

    Science.gov (United States)

    Jin, Pengkang; Wang, Xianbao; Wang, Xiaochang; Ngo, Huu Hao; Jin, Xin

    2015-12-01

    Two aeration modes, step aeration and point aeration, were used in a full-scale Carrousel oxidation ditch with microporous aeration. The nitrogen removal performance and mechanism were analyzed. With the same total aeration input, both aeration modes demonstrated good nitrification outcomes with the average efficiency in removing NH4(+)-N of more than 98%. However, the average removal efficiencies for total nitrogen were 89.3% and 77.6% under step aeration and point aeration, respectively. The results indicated that an extended aerobic zone followed the aeration zones could affect the proportion of anoxic and oxic zones. The step aeration with larger anoxic zones indicated better TN removal efficiency. More importantly, step aeration provided the suitable environment for both nitrifiers and denitrifiers. The diversity and relative abundance of denitrifying bacteria under the step aeration (1.55%) was higher than that under the point aeration (1.12%), which resulted in an overall higher TN removal efficiency. PMID:26363498

  20. Characterization of Odorant Compounds from Mechanical Aerated Pile Composting and Static Aerated Pile Composting.

    Science.gov (United States)

    Kumari, Priyanka; Lee, Joonhee; Choi, Hong-Lim

    2016-04-01

    We studied airborne contaminants (airborne particulates and odorous compounds) emitted from compost facilities in South Korea. There are primarily two different types of composting systems operating in Korean farms, namely mechanical aerated pile composting (MAPC) and aerated static pile composting (SAPC). In this study, we analyzed various particulate matters (PM10, PM7, PM2.5, PM1, and total suspended particles), volatile organic compounds and ammonia, and correlated these airborne contaminants with microclimatic parameters, i.e., temperature and relative humidity. Most of the analyzed airborne particulates (PM7, PM2.5, and PM1) were detected in high concentration at SAPC facilities compered to MAPC; however these differences were statistically non-significant. Similarly, most of the odorants did not vary significantly between MAPC and SAPC facilities, except for dimethyl sulfide (DMS) and skatole. DMS concentrations were significantly higher in MAPC facilities, whereas skatole concentrations were significantly higher in SAPC facilities. The microclimate variables also did not vary significantly between MAPC and SAPC facilities, and did not correlate significantly with most of the airborne particles and odorous compounds, suggesting that microclimate variables did not influence their emission from compost facilities. These findings provide insight into the airborne contaminants that are emitted from compost facilities and the two different types of composting agitation systems. PMID:26949962

  1. Pure and aerated water entry of a flat plate

    Science.gov (United States)

    Ma, Z. H.; Causon, D. M.; Qian, L.; Mingham, C. G.; Mai, T.; Greaves, D.; Raby, A.

    2016-01-01

    This paper presents an experimental and numerical investigation of the entry of a rigid square flat plate into pure and aerated water. Attention is focused on the measurement and calculation of the slamming loads on the plate. The experimental study was carried out in the ocean basin at Plymouth University's COAST laboratory. The present numerical approach extends a two-dimensional hydro-code to compute three-dimensional hydrodynamic impact problems. The impact loads on the structure computed by the numerical model compare well with laboratory measurements. It is revealed that the impact loading consists of distinctive features including (1) shock loading with a high pressure peak, (2) fluid expansion loading associated with very low sub-atmospheric pressure close to the saturated vapour pressure, and (3) less severe secondary reloading with super-atmospheric pressure. It is also disclosed that aeration introduced into water can effectively reduce local pressures and total forces on the flat plate. The peak impact loading on the plate can be reduced by half or even more with 1.6% aeration in water. At the same time, the lifespan of shock loading is prolonged by aeration, and the variation of impulse is less sensitive to the change of aeration than the peak loading.

  2. Methanogenesis acceleration of fresh landfilled waste by micro-aeration

    Institute of Scientific and Technical Information of China (English)

    SHAO Li-ming; HE Pin-jing; ZHANG Hua; YU Xiao-hua; LI Guo-jian

    2005-01-01

    When municipal solid waste(MSW) with high content of food waste is landfilled, the rapid hydrolysis of food waste results in the imbalance of anaerobic metabolism in the landfill layer, indicated by accumulation of volatile fatty acids(VFA) and decrease of pH value.This occurrence could lead to long lag time before the initiation of methanogenesis and to the production of strong leachate. Simulated landfill columns with forced aeration, with natural ventilation, and with no aeration, were monitored regarding their organics degradation rate with leachate recirculation. Hydrolysis reactions produced strong leachate in the column with no aeration. With forced aeration, the produced VFA could be effectively degraded, leading to the reduction in COD of the leachate effluent since the week 3. The CH4 in the frequency of twice/d, could amount to 40% (v/v) after only 20 weeks. This amount had increased up to 50% afterward even with no aeration. Most of COD in the recirculated leachate was removed. Using natural ventilation, CH4 could also be produced and the COD of the leachate effluent be reduced after 10 weeks of operation. However, the persistent existence of oxygen in the landfill layer yielded instability in methanogenesis process.

  3. Aspects concerning the quality of aeration for environmental friendly turbines

    Science.gov (United States)

    Bunea, F.; Houde, S.; Ciocan, G. D.; Oprina, G.; Baran, G.; Pincovschi, I.

    2010-08-01

    The hydro renewable energy provides a reliable power source; it does not pollute the air or land but affects the aquatic habitat due to low dissolved oxygen (DO) level in the water discharged from turbines. Hydro-turbines intake generally withdraws water from the bottom layer of the reservoirs with low DO level. In the different methods used for improving DO downstream the hydropower plants the volume of air is considered to be the main parameter of the injection. The energetic consumption is affected, in terms of loss of turbine efficiency due to air injection. The authors propose a study to show the importance of the quality of air injection, meaning bubble size, pressure loss on the aeration device etc. Different types of fine bubble aeration systems have been tested and compared. The capacity to predict the aeration by numerical simulation is analysed.

  4. Aspects concerning the quality of aeration for environmental friendly turbines

    International Nuclear Information System (INIS)

    The hydro renewable energy provides a reliable power source; it does not pollute the air or land but affects the aquatic habitat due to low dissolved oxygen (DO) level in the water discharged from turbines. Hydro-turbines intake generally withdraws water from the bottom layer of the reservoirs with low DO level. In the different methods used for improving DO downstream the hydropower plants the volume of air is considered to be the main parameter of the injection. The energetic consumption is affected, in terms of loss of turbine efficiency due to air injection. The authors propose a study to show the importance of the quality of air injection, meaning bubble size, pressure loss on the aeration device etc. Different types of fine bubble aeration systems have been tested and compared. The capacity to predict the aeration by numerical simulation is analysed.

  5. Experimental Analysis of Pressure Fluctuations behind a Bottom Aerator

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Experimental observations show that the random process of two-phase flow beh ind an aerator is an ergodic process and its amplitude distribution is similar t o a normal distribution. The maximum pressure fluctuation is at the re-attachme n t point where the jet-trajectory flow over the aerator re-attaches to bottom o f the channel, and its amplitude is 2-3 times larger than when there is no aerato r. There is a dominant frequency of 1.24 Hz in the model, but the coherence in th e frequency domain is not obvious for other frequencies beside the dominant frequ ency. There is a large vortex at the re-attachment point behind the aerator but correlation among the measurement points is not obvious in the time domain.

  6. RE-AERATION LAW OF WATER FLOW OVER SPILLWAYS

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiang-ju; LUO Lin; CHEN Yong-can; ZHAO Wen-qian

    2006-01-01

    In order to explore the re-aeration law of water flow over spillway, the transfer process of oxygen in water flow over spillway was studied. The interfacial mass transfer coefficients were obtained by experiments. The flow fields and the turbulence characteristics are simulated by numerical methods. The fractional volume of fluid model (VOF) of the air-water two phase flows was introduced to track the interface. Consequently, the quantitative expression of the interfacial mass transfer coefficients related with velocity and kinetic energy at the free surface was derived and the re-aeration model for the water flow over spillway was established. The examination with the experimental data of different conditions shows the validity of the re-aeration model for the water flow over spillways. This study will be important to evaluate the dissolved oxygen concentration and self-purification ability of rivers.

  7. Studies of radon mitigation in well water by aeration

    International Nuclear Information System (INIS)

    The 222Rn concentration in natural water in different countries usually is about few Bq/L and is the subject of the National legislation as well as International norms and recommendations. The United States Environmental Protection Agency (USEPA) established a limit of 11.1 Bq/L for the radon level in drinking water and this limit is considered as guideline in Canada and many countries of the European Union. This work presents the results of study of radon (222Rn) concentration reduction in well water using the aeration process developed at the Laboratory of Applied Nuclear Physics of the Federal University of Technology (UTFPR). The water samples were collected from a well at Pinheirinho region of Curitiba in 2011. Experimental setup was based on the Radon Monitor (AlphaGUARD). The 222Rn concentration was analyzed using the software DataEXPERT by Genitron Instruments, taking into account the volume of water sample, its temperature, atmospheric pressure and the total volume of the air in the vessels. Initial concentration of radon in water samples was 28,67 Bq/L which is bigger than maximum concentration recommended by USEPA. The mitigation was performed by means of diffusion aeration of water samples of 15L during the time interval of 24 hours following a period of 4 days. The efficiency of aeration mitigation was controlled by comparing the activity of radon in aerated water with reference water samples that were not aerated. Obtained results show very satisfactory decrease of 222Rn activity in water samples even after few hours of intense aeration. (author)

  8. INVESTIGATION ON THE SPLASH LENGTH OF THE AERATED JET

    Institute of Scientific and Technical Information of China (English)

    Liu Shi-he; Qu Bo

    2003-01-01

    Atomized flow forms as an aerated jet from high dams impacts against the downstream water surface at high speed. Of all the regions of atomized flow the splash region is in the center of storm rainfall, which might cause certain damage to the hydropower stations and thence more attention should be paid. In this paper the impact of the water drop at the outer edge of the aerated jet against the downstream water surface was analyzed, and the motion of the splash water drop was investigated. Furthermore, a new formula for the calculation of the splash length was suggested, which is in good agreement with the data of model tests and prototype observation.

  9. Modelling and test of aeration tank settling (ATS)

    DEFF Research Database (Denmark)

    Nielsen, M. K.; Bechmann, H.; Henze, Mogens

    2000-01-01

    The use of aeration tank settling during high hydraulic loads on large wastewater treatment plants has previously been demonstrated as a reliable technique and proven valuable. The paper proposes a simplified deterministic model to predict the efficiency of the method. It is shown that a qualitat......The use of aeration tank settling during high hydraulic loads on large wastewater treatment plants has previously been demonstrated as a reliable technique and proven valuable. The paper proposes a simplified deterministic model to predict the efficiency of the method. It is shown that a...

  10. Hydrodynamic behaviour of the lateral flow biological aerated filter

    Institute of Scientific and Technical Information of China (English)

    HE Qiang; WANG Yin; FANG Jun-hua; ZHANG Hong-jing; XU Jing

    2006-01-01

    Pulsed signal experiment was carried out to determine the hydrodynamic behaviours of lateral flow biological aerated filter(LBAF). With the analysis of experimental results, LBAF is viewed as an approximate plug flow reactor, and hydraulic retention time distribution function was derived based on LBAF. The results show that flow rate and aeration strength are two critical factors which influence flow patterns in LBAF reactor. The hydrodynamic behaviour analysis of LBAF is the theoretical basis of future research on improving capacity factor and developing kinetic model for the reactor.

  11. AERATION EFFECT OF SUBMERGED JET ON HYDRAULIC CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A water-air two-phase turbulence mathematical model was proposed, The mass-weighted average was adoptedfor velocity, air mass fraction and turbulent parameters. Thealgebraic stress equation was used to calculate the Reynoldsstress. The pulsating flux of air mass fraction was simulatedby employing the concept of the eddy viscosity. The numericalsimulation of aerated flow in plunge pool shows that, for the same depth, aeration may decrease the time-averaged pressureon pool floor and increase slightly the turbulent intensity. Thecomputed concentration and pressure distributions coincidewith the experimental data.

  12. Characteristics of integrated biological aerated filter in municipal wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    HE Qiang; ZHANG Yu-ping; XU Jian-bin

    2005-01-01

    In this paper, the characteristics of integrated biological aerated filter (IBAF) applied to municipal wastewater treatment were studied in a pilot scale experiment. The experimental results showed that IBAF has high efficiencies in removing organic pollutants, such as CODCr and SS, in municipal wastewater. The removal rates of CODCr and SS can reach over 90% and 80%, respectively, when COD and SS in the influent are 234 mg L-1 and 112 mg L-1, hydraulic retention time (HRT) is 8 h, and the aerated intensity is in the range of (0.5 to 0.6) L m-2 s-1.

  13. Case study of aeration performance under changing process conditions

    DEFF Research Database (Denmark)

    Iranpour, R.; Shao, Y.J.; Ahring, Birgitte Kiær;

    2002-01-01

    Off gas analyses of oxygen transfer efficiency (OTE) at Terminal Island Treatment Plant of Los Angeles document changing performance of fine-pore diffusers in an activated sludge plant from 1991 to 1998. Although the plant treats a challenging waste stream, the aeration tanks are little different...... from other plants. Recent sessions provided improved time and space resolution, compared to previous work. Samples were more closely spaced, and some samples were taken in the intervals between the aeration grids, at the ends of the tanks, and near the edges of the grids. Very short term fluctuations...

  14. Relation between Shunt, Aeration, and Perfusion in Experimental Acute Lung Injury

    OpenAIRE

    Musch, Guido; Bellani, Giacomo; Vidal Melo, Marcos F; Harris, R. Scott; Winkler, Tilo; Schroeder, Tobias; Venegas, Jose G

    2007-01-01

    Rationale: In a pulmonary process characterized by spatially heterogeneous loss of aeration, the impairment of gas exchange is expected to depend on the regional distribution of perfusion relative to that of aeration.

  15. In-tank aeration, a necessary compliment of loaded systems in an airlift recirculating aquaculture system

    Science.gov (United States)

    Water treatment components in recirculating aquaculture systems in generally address solids removal, nitrification, circulation, aeration, and degasification. Airlift pumps in a recirculating aquaculture system can address water circulation, aeration, and degasification. Recent data indicates oxygen...

  16. Sequential Aeration of Membrane-Aerated Biofilm Reactors for High-Rate Autotrophic Nitrogen Removal: Experimental Demonstration

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Sun, Sheng-Peng; Lackner, Susanne;

    2010-01-01

    One-stage autotrophic nitrogen (N) removal, requiring the simultaneous activity of aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB), can be obtained in spatially redox-stratified biofilms. However, previous experience with Membrane-Aerated Biofilm Reactors (MABRs) has revealed a...... difficulty in reducing the abundance and activity of nitrite oxidizing bacteria (NOB), which drastically lowers process efficiency. Here we show how sequential aeration is an effective strategy to attain autotrophic N removal in MABRs: Two separate MABRs, which displayed limited or no N removal under......S rRNA gene confirmed that sequential aeration, even at elevated average O2 loads, stimulated the abundance of AnAOB and AOB and prevented the increase in NOB. Nitrous oxide (N2O) emissions were 100-fold lower compared to other anaerobic ammonium oxidation (Anammox)-nitritation systems. Hence, by...

  17. Development and evaluation of a new aerator for the catfish industry

    Science.gov (United States)

    Traditional paddle-wheel aerators have been used for supplemental and emergency aeration in the aquaculture industry for over 30 years but distribute a high volume of water which dilutes the aeration effort over the entire pond volume. Thus, a great deal of equipment and a large amount of power is r...

  18. Influence of aeration degree of cultural liquid on biosintetical activity of fungus culture Blakeslea trispora

    OpenAIRE

    A. S. Anatsky; Y. A. Kunshchikova

    2009-01-01

    Β-carotene biosynthetic processes of the fungus Blakeslea trispora are studied for different technological modes of cultural liquid aeration under industrial conditions. It is shown, that the increase of aeration degree stimulates the accumulation of biomass and carotene’s formation. The operating practices of the maximal aeration since the 10th hour of cultivation are recommended to the use.

  19. Effect of pond aeration on growth and survival of Penaeus monodon Fab.

    OpenAIRE

    R. K. Mohanty

    2001-01-01

    The effect of paddle wheel aeration on shrimp growth and survival were studied at a commercial farm at Chandipur coast of Orissa, India, at different stocking densities of Penaeus monodon. Four different aeration patterns were adopted and evaluated. Influence of individual aeration pattern on average survival rate was not highly significant (p

  20. Intermittent aeration to improve wastewater treatment efficiency in pilot-scale constructed wetland.

    Science.gov (United States)

    Uggetti, Enrica; Hughes-Riley, Theodore; Morris, Robert H; Newton, Michael I; Trabi, Christophe L; Hawes, Patrick; Puigagut, Jaume; García, Joan

    2016-07-15

    Forced aeration of horizontal subsurface flow constructed wetlands (HSSF CWs) is nowadays a recognized method to improve treatment efficiency, mainly in terms of ammonium removal. While numerous investigations have been reported testing constant aeration, scarce information can be found about the efficiency of intermittent aeration. This study aims at comparing continuous and intermittent aeration, establishing if there is an optimal regime that will increase treatment efficiency of HSSF CWs whilst minimizing the energy requirement. Full and intermittent aeration were tested in a pilot plant of three HSSF CWs (2.64m(2) each) fed with primary treated wastewater. One unit was fully aerated; one intermittently aerated (i.e. by setting a limit of 0.5mg/L dissolved oxygen within the bed) with the remaining unit not aerated as a control. Results indicated that intermittent aeration was the most successful operating method. Indeed, the coexistence of aerobic and anoxic conditions promoted by the intermittent aeration resulted in the highest COD (66%), ammonium (99%) and total nitrogen (79%) removals. On the other hand, continuous aeration promotes ammonium removal (99%), but resulted in nitrate concentrations in the effluent of up to 27mg/L. This study demonstrates the high potential of the intermittent aeration to increase wastewater treatment efficiency of CWs providing an extreme benefit in terms of the energy consumption. PMID:27062558

  1. Directional Flow of Summer Aeration to Manage Insect Pests in Stored Wheat

    Science.gov (United States)

    Field trials were conducted in metal wheat storage bins to determine whether pressure aeration, pushing ambient air from the bottom, or suction aeration, pulling air down from the top, would be more efficient at cooling the wheat mass and thereby limiting insect population growth. Aeration was accom...

  2. 7 CFR 201.55a - Moisture and aeration of substratum.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Moisture and aeration of substratum. 201.55a Section... and aeration of substratum. (a) The substratum must be moist enough to supply the needed moisture to the seeds at all times. Excessive moisture which will restrict aeration of the seeds should be...

  3. Non-autoclaved aerated concrete with mineral additives

    Science.gov (United States)

    Il'ina, L. V.; Rakov, M. A.

    2016-01-01

    We investigated the effect of joint grinding of Portland cement clinker, silica and carbonate components and mineral additives to specific surface of 280 - 300 m2/kg on the properties (strength, average density and thermal conductivity) of non-autoclaved aerated concrete, and the porosity of the hardened cement paste produced from Portland cement clinker with mineral additives. The joint grinding of the Portland cement clinker with silica and carbonate components and mineral additives reduces the energy consumption of non-autoclaved aerated concrete production. The efficiency of mineral additives (diopside, wollastonite) is due to the closeness the composition, the type of chemical bonds, physical and chemical characteristics (specific enthalpy of formation, specific entropy) to anhydrous clinker minerals and their hydration products. Considering the influence of these additions on hydration of clinker minerals and formation of hardened cement paste structure, dispersed wollastonite and diopside should be used as mineral additives. The hardness and, consequently, the elastic modulus of diopside are higher than that of hardened cement paste. As a result, there is a redistribution of stresses in the hardened cement paste interporous partitions and hardening, both the partitions and aerated concrete on the whole. The mineral additives introduction allowed to obtain the non-autoclaved aerated concrete with average density 580 kg/m3, compressive strength of 3.3 MPa and thermal conductivity of 0.131 W/(m.°C).

  4. Little River Pond Mill a wind-powered lagoon aerator

    International Nuclear Information System (INIS)

    The Little River Pond Mill is a wind-driven surface aerator designed to be used in facultative wastewater treatment plants. The aerator consists of an eight-blade wind turbine which is mounted to a gear box that transmits torque through the shaft to the impeller. A swing tail rotates the turbine into the wind and stabilizes the unit in high winds. This study was designed to investigate how the Little River Pond Mill operated in a lagoon environment, how it affected the performance of the lagoon, and to measure the oxygen transfer rate for a field-determined wind speed. Strong mixing capabilities have been observed in both the dugout and the lagoon installations even at low windspeeds. With the installation of the aerator there was a reduction in BOD and NH3N. The oxygen transfer rate was found to be 1.47 g O2/W h at an average wind speed of 19 km/h. Due to the Pond Mill's low power requirement, this aeration efficiency has been rated as 'quite reasonable' for this wind speed. 5 refs., 10 figs

  5. Tailwater concerns and the history of turbine aeration

    International Nuclear Information System (INIS)

    All new proposals for hydropower development and many of the almost 300 hydroelectric projects which will be relicensed before 2000 will have to address the issue of minimum dissolved oxygen concentrations. This paper highlights some of the causes and concerns of low dissolved oxygen concentrations in releases from hydropower projects and describes the history of hydroturbine aeration for reaerating these releases

  6. Fin characteristics of aerator devices with lateral deflectors

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; LI Dan; MA Fei; QIAN Shang-tuo

    2013-01-01

    The fins will be formed if the lateral deflectors in the side-walls with a bottom aerator device are improperly designed,and the flow regime downstream of the aerator device will be worsened.In this paper,the height and the length of the fins induced by the lateral deflectors are theoretically analyzed along with their influencing factors,and the fin characteristics are experimentally investigated on the basis of the theoretical analysis.It is shown that the intensities of the fins are strongly dependent on the ratio of the lateral cavity length to the bottom cavity length,and other factors,like the working head,the height and the angle of the lateral deflector,the flow Froude number around the aerator device,affect the fins indirectly through the changes of the lateral cavity length.When an aerator device with lateral deflectors is designed,it is crucial to match the above mentioned ratio,and to make the ratio of the two cavity lengths less than 1.0 in order to avoid the generation of the fins.

  7. No-till bioenergy cropping systems effect on soil aeration

    Science.gov (United States)

    Bioenergy cropping systems have been proposed as a way to enhance United States energy security. However, research on soil quality, such as the effects of maize stover harvesting on soil aeration and the relationships to soil structure and water, associated with bioenergy cropping systems has been l...

  8. HYDRAULIC CHARACTERISTICS OF CHUTE AERATORS FOR RELEASE WORKS

    Institute of Scientific and Technical Information of China (English)

    RUAN Shi-ping

    2008-01-01

    On the basis of model tests and theoretical analysis, hydraulic characteristics, air demand, air concentration distribution and their relationships between prototype and model of an aerator were studied. Some computational examples show that the present methods have higher accuracy, and can meet the need of engineering design.

  9. Aeration of bread dough influenced by different way processing

    NARCIS (Netherlands)

    Peighambardoust, S.H.; Fallah, E.; Hamer, R.J.; Goot, van der A.J.

    2010-01-01

    The effect of steady shearing versus z-blade mixing on mechanical aeration and gas retaining ability of the dough during processing and subsequent proofing and bread baking stages was investigated. Reduction in moisture content led to reduction in both static and dynamic densities of z-blade mixed d

  10. Nutrients removal using moving beds with aeration cycles

    International Nuclear Information System (INIS)

    Moving Bed Biofilm Reactors (MBBR) are based on the biomass growth over a media that moves into the reactor due to aeration, mechanical agitation or recirculation. These reactors have been gaining popularity and they are employed in hundreds of plants everywhere with different treatment purposes (organic matter removal, nitrification/denitrification), both for urban and industrial wastewater. (Author)

  11. Ventilation/perfusion mismatch during lung aeration at birth.

    Science.gov (United States)

    Lang, Justin A R; Pearson, James T; te Pas, Arjan B; Wallace, Megan J; Siew, Melissa L; Kitchen, Marcus J; Fouras, Andreas; Lewis, Robert A; Wheeler, Kevin I; Polglase, Graeme R; Shirai, Mikiyasu; Sonobe, Takashi; Hooper, Stuart B

    2014-09-01

    At birth, the transition to newborn life is triggered by lung aeration, which stimulates a large increase in pulmonary blood flow (PBF). Current theories predict that the increase in PBF is spatially related to ventilated lung regions as they aerate after birth. Using simultaneous phase-contrast X-ray imaging and angiography we investigated the spatial relationships between lung aeration and the increase in PBF after birth. Six near-term (30-day gestation) rabbits were delivered by caesarean section, intubated and an intravenous catheter inserted, before they were positioned for X-ray imaging. During imaging, iodine was injected before ventilation onset, after ventilation of the right lung only, and after ventilation of both lungs. Unilateral ventilation increased iodine levels entering both left and right pulmonary arteries (PAs) and significantly increased heart rate, iodine ejection per beat, diameters of both left and right PAs, and number of visible vessels in both lungs. Within the 6th intercostal space, the mean gray level (relative measure of iodine level) increased from 68.3 ± 11.6 and 70.3 ± 7.5%·s to 136.3 ± 22.6 and 136.3 ± 23.7%·s in the left and right PAs, respectively. No differences were observed between vessels in the left and right lungs, despite the left lung not initially being ventilated. The increase in PBF at birth is not spatially related to lung aeration allowing a large ventilation/perfusion mismatch, or pulmonary shunting, to occur in the partially aerated lung at birth. PMID:24994883

  12. The potential for aeration of MSW landfills to accelerate completion

    International Nuclear Information System (INIS)

    Landfilling is a popular waste disposal method, but, as it is practised currently, it is fundamentally unsustainable. The low short-term financial costs belie the potential long-term environmental costs, and traditional landfill sites require long-term management in order to mitigate any possible environmental damage. Old landfill sites might require aftercare for decades or even centuries, and in some cases remediation may be necessary. Biological stabilisation of a landfill is the key issue; completion criteria provide a yardstick by which the success of any new technology may be measured. In order for a site to achieve completion it must pose no risk to human health or the environment, meaning that attenuation of any emissions from the site must occur within the local environment without causing harm. Remediation of old landfill sites by aerating the waste has been undertaken in Germany, the United States, Italy and The Netherlands, with considerable success. At a pilot scale, aeration has also been used in newly emplaced waste to accelerate stabilisation. This paper reviews the use of aerobic landfill worldwide, and assesses the ways in which the use of aerobic landfill techniques can decrease the risks associated with current landfill practices, making landfill a more sustainable waste disposal option. It focuses on assessing ways to utilise aeration to enhance stabilisation. The results demonstrated that aeration of old landfill sites may be an efficient and cost-effective method of remediation and allow the date of completion to be brought forward by decades. Similarly, aeration of newly emplaced waste can be effective in enhancing degradation, assisting with completion and reducing environmental risks. However, further research is required to establish what procedure for adding air to a landfill would be most suitable for the UK and to investigate new risks that may arise, such as the possible emission of non-methane organic compounds

  13. Nitrous oxide emissions from an intermittent aeration activated sludge system of an urban wastewater treatment plant

    OpenAIRE

    William Z. de Mello; Renato P. Ribeiro; Ariane C. Brotto; Débora C. Kligerman; Andrezza de S. Piccoli; Jaime L. M. Oliveira

    2013-01-01

    This study investigated the emission of N2O during the sequential aerated (60-min) and non-aerated (30-min) stages of an intermittent aeration cycle in an activated sludge wastewater treatment plant (WWTP). N2O emission occurred during both stages; however, emission was much higher during aeration. Air stripping is the major factor controlling transfer of N2O from the sewage to the atmosphere. The N2O emissions exclusively from the aeration tank represented 0.10% of the influent total nitroge...

  14. Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast.

    Science.gov (United States)

    Liu, Chen-Guang; Hao, Xue-Mi; Lin, Yen-Han; Bai, Feng-Wu

    2016-01-01

    Ethanol fermentation requires oxygen to maintain high biomass and cell viability, especially under very-high-gravity (VHG) condition. In this work, fermentation redox potential (ORP) was applied to drive the aeration process at low dissolved oxygen (DO) levels, which is infeasible to be regulated by a DO sensor. The performance and characteristics of flocculating yeast grown under 300 and 260 g glucose/L conditions were subjected to various aeration strategies including: no aeration; controlled aeration at -150, -100 and -50 mV levels; and constant aeration at 0.05 and 0.2 vvm. The results showed that anaerobic fermentation produced the least ethanol and had the highest residual glucose after 72 h of fermentation. Controlled aerations, depending on the real-time oxygen demand, led to higher cell viability than the no-aeration counterpart. Constant aeration triggered a quick biomass formation, and fast glucose utilization. However, over aeration at 0.2 vvm caused a reduction of final ethanol concentration. The controlled aeration driven by ORP under VHG conditions resulted in the best fermentation performance. Moreover, the controlled aeration could enhance yeast flocculating activity, promote an increase of flocs size, and accelerate yeast separation near the end of fermentation. PMID:27161047

  15. Performance of completely autotrophic nitrogen removal over nitrite process under different aeration modes and dissolved oxygen

    Institute of Scientific and Technical Information of China (English)

    Jinsong GUO; Guohong YANG; Fang FANG; Yu QIN

    2008-01-01

    In this study, three sequential batch biofilm reactors (SBBRs) were operated for 155 days to evaluate the performance of completely autotrophic nitrogen removal over nitrite (CANON) process under different aeration modes and dissolved oxygen (DO). Synthetic wastewater with 160-mg NH4+-N/L was fed into the reac-tors. In the continuously-aerated reactor, the efficiency of the ammonium nitrogen conversion and total nitrogen (TN) removal reached 80% and 70%, respectively, with DO between 0.8-1.0 mg/L. Whereas in the intermit-tently-aerated reactor, at the aeration/non-aeration ratio of 1.0, ammonium was always under the detection limit and 86% of TN was removed with DO between 2.0 2.5 mg/L during the aeration time. Results show that CANON could be achieved in both continuous and inter-mittent aeration pattern. However, to achieve the same nitrogen removal efficiency, the DO needed in the inter-mittently-aerated sequential batch biofilm reactor (SBBR) during the aeration period was higher than that in the continuously-aerated SBBR. In addition, the DO in the CANON system should be adjusted to the aeration mode, and low DO was not a prerequisite to CANON process.

  16. Effective pine bark composting with the Dome Aeration Technology

    International Nuclear Information System (INIS)

    In South Africa garden refuse is primarily disposed of in domestic landfills. Due to the large quantities generated, any form of treatment would be beneficial for volume reduction, waste stabilization and resource recovery. Dome Aeration Technology (DAT) is an advanced process for aerobic biological degradation of garden refuse and general waste [Paar, S., Brummack, J., Gemende, B., 1999a. Advantages of dome aeration in mechanical-biological waste treatment. In: Proceedings of the 7th International Waste Management and Landfill Symposium, Cagliari, 4-8 October 1999; Paar, S., Brummack, J., Gemende, B., 1999b. Mechanical-biological waste stabilization by the dome aeration method. Environment Protection Engineering 25 (3/99). Mollekopf, N., Brummack, J., Paar, S., Vorster, K., 2002. Use of the Dome Aeration Technology for biochemical stabilization of waste prior to landfilling. In: Proceedings of the Wastecon 2002, Waste Congress and Exhibition, Durban, South Africa.]. It is a non-reactor open windrow composting process, with the main advantage being that the input material needs no periodic turning. A rotting time of only 3-4 months indicates the high efficiency. Additionally, the low capital/operational costs, low energy inputs and limited plant requirements provide potential for use in aerobic refuse stabilization. The innovation in the DAT process is the passive aeration achieved by thermally driven advection through open windrows caused by temperature differences between the degrading material and the outside environment. This paper investigates the application of Dome Aeration Technology to pine bark composting as part of an integrated waste management strategy. A full-scale field experiment was performed at the Bisasar Road Landfill Site in Durban to assess the influence of climate, waste composition and operational conditions on the process. A test windrow was constructed and measurements of temperature and airflow through the material were taken. The process

  17. Radon removal from water supplies by diffused bubble aeration system

    International Nuclear Information System (INIS)

    The removal efficiency of moderate levels of radon from groundwater supplies was evaluated using the diffused bubble aeration technique. An aeration system was designed, constructed and operated for that purpose. The effect of air-to-water ratio and detention time on radon removal were evaluated through 32 runs. The possibility to reduce the radon activity in the influent stream to the U.S. Environmental Protection Agency proposed maximum contaminant level (MCL) was verified through many alternative combined values of both air-to-water ratios and detention times. The results showed that at detention time of 19 minutes and air-to-water ratio of 12, the average radon removal is about 97%. The stripping constant characterizing this system was calculated and the removal efficiency at extended values of detention time was predicted. The data obtained are site specific, being dependent on container size, type of diffusers, temperature, and influent radon radioactivity. (author)

  18. Feasibility of biological aerated filters (BAFs) for treating landfill leachate.

    OpenAIRE

    Stephenson, Tom; Pollard, Simon J. T.; Cartmell, Elise

    2004-01-01

    Ammonia can be removed from landfill leachate through aerobic biological processes. The biological aerated filter (BAF) combines biological treatment and subsequent biomass separation in one reactor providing a small footprint alternative to conventional systems. Leachate from an operational landfill was found to be aerobically treatable using the OECD recommended Modified Zahn- Wellens test. This leachate was used as feed to a pilot-scale BAF at influent COD and ammoniacal-...

  19. Landfill aeration for emission control before and during landfill mining.

    Science.gov (United States)

    Raga, Roberto; Cossu, Raffaello; Heerenklage, Joern; Pivato, Alberto; Ritzkowski, Marco

    2015-12-01

    The landfill of Modena, in northern Italy, is now crossed by the new high velocity railway line connecting Milan and Bologna. Waste was completely removed from a part of the landfill and a trench for the train line was built. With the aim of facilitating excavation and further disposal of the material extracted, suitable measures were defined. In order to prevent undesired emissions into the excavation area, the aerobic in situ stabilisation by means of the Airflow technology took place before and during the Landfill Mining. Specific project features involved the pneumatic leachate extraction from the aeration wells (to keep the leachate table low inside the landfill and increase the volume of waste available for air migration) and the controlled moisture addition into a limited zone, for a preliminary evaluation of the effects on process enhancement. Waste and leachate were periodically sampled in the landfill during the aeration before the excavation, for quality assessment over time; the evolution of biogas composition in the landfill body and in the extraction system for different plant set-ups during the project was monitored, with specific focus on uncontrolled migration into the excavation area. Waste biological stability significantly increased during the aeration (waste respiration index dropped to 33% of the initial value after six months). Leachate head decreased from 4 to 1.5m; leachate recirculation tests proved the beneficial effects of moisture addition on temperature control, without hampering waste aerobization. Proper management of the aeration plant enabled the minimization of uncontrolled biogas emissions into the excavation area. PMID:26445364

  20. Modeling of damage due to shrinkage in autoclaved aerated concrete

    OpenAIRE

    Koudelka, T.; Kruis, J.; Sysala, S.; M. Vokáč

    2015-01-01

    The paper deals with numerical modeling of damage evolution in autoclaved aerated concrete (AAC) due to shrinkage. It represents coupled thermo-hydro-mechanical problem where the temperature and moisture transports are fully coupled. The mechanical problem is partially coupled with transport part because the AAC shrinkage is influenced by moisture evolution. These models were implemented to the SIFEL software package and they were used for numerical simulation of drying wall made from AAC blo...

  1. Optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits.

    Science.gov (United States)

    Ozkan, Fahri; Tuna, M Cihat; Baylar, Ahmet; Ozturk, Mualla

    2014-01-01

    Oxygen is an important component of water quality and its ability to sustain life. Water aeration is the process of introducing air into a body of water to increase its oxygen saturation. Water aeration can be accomplished in a variety of ways, for instance, closed-conduit aeration. High-speed flow in a closed conduit involves air-water mixture flow. The air flow results from the subatmospheric pressure downstream of the gate. The air entrained by the high-speed flow is supplied by the air vent. The air entrained into the flow in the form of a large number of bubbles accelerates oxygen transfer and hence also increases aeration efficiency. In the present work, the optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits was studied experimentally. Results showed that aeration efficiency increased with the air-demand ratio to a certain point and then aeration efficiency did not change with a further increase of the air-demand ratio. Thus, there was an optimum value for the air-demand ratio, depending on the Froude number, which provides maximum aeration efficiency. Furthermore, a design formula for aeration efficiency was presented relating aeration efficiency to the air-demand ratio and Froude number. PMID:25225935

  2. In situ nitrogen removal from leachate by bioreactor landfill with limited aeration

    International Nuclear Information System (INIS)

    The feasibility of simultaneous nitrification and denitrification in a bioreactor landfill with limited aeration was assessed. Three column reactors, simulating bioreactor landfill operations under anaerobic condition (as reference), intermittent forced aeration and enhanced natural aeration were hence established, where aerated columns passed through two phases, i.e., fresh landfill and well-decomposed landfill. The experimental results show that limited aeration decreased nitrogen loadings of leachate distinctly in the fresh landfill. In the well-decomposed landfill, the NH4+-N of the input leachate could be nitrified completely in the aerated landfill columns. The nitrifying loadings of the column cross section reached 7.9 g N/m2 d and 16.9 g N/m2 d in the simulated landfill columns of intermittent forced aeration and enhanced natural aeration, respectively. The denitrification was influenced by oxygen distribution in the landfill column. Intermittent existence of oxygen in the landfill with the intermittent forced aeration was favorable to denitrify the NO2--N and NO3--N, indicated by the high denitrification efficiency (>99%) under the condition of BOD5/TN of more than 5.4 in leachate; locally persistent existence of oxygen in the landfill with enhanced natural aeration could limit the denitrification, indicated by relatively low denitrification efficiency of about 75% even when the BOD5/TN in leachate had an average of 7.1

  3. Violent breaking wave impacts. Part 3. Effects of scale and aeration

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Bullock, G. N.; Hogg, A. J.

    2015-01-01

    The effects of scale and aeration on violent breaking wave impacts with trapped and entrained air are investigated both analytically and numerically. By dimensional analysis we show that the impact pressures for Froude scaled conditions prior to the impact depend on the scale and aeration level....... The Bagnold-Mitsuyasu scaling law for the compression of an air pocket by a piston of incompressible water is rederived and generalised to 3D air pockets of arbitrary shape. Numerical results for wall pressure, force and impulse are then presented for a flip-through impact, a low-aeration impact and a...... high-aeration impact, for nine scales and five levels of initial aeration. Two of these impact types trap a pocket of air at the wall. Among the findings of the paper is that for fixed initial aeration, impact pressures from the flip-through impact broadly follow Froude scaling. This is also the case...

  4. Effects of aeration position on organics, nitrogen and phosphorus removal in combined oxidation pond-constructed wetland systems.

    Science.gov (United States)

    Wang, Xiaoou; Tian, Yimei; Zhao, Xinhua; Peng, Sen; Wu, Qing; Yan, Lijian

    2015-12-01

    Given that few studies investigated the effects of aeration position (AP) on the performance of aerated constructed wetlands, the aim of this study was to evaluate the effects of AP on organics, nitrogen and phosphorus removal in lab-scale combined oxidation pond-constructed wetland (OP-CW) systems. Results showed that middle aeration allowed the CW to possess more uniform oxygen distribution and to achieve greater removals of COD and NH3-N, while the CW under bottom aeration and surface aeration demonstrated more distinct stratification of oxygen distribution and surface aeration brought about better TN removal capacity for the OP-CW system. However, no significant influence of artificial aeration or AP on TP removal was observed. Overall, AP could significantly affect the spatial distribution of dissolved oxygen by influencing the oxygen diffusion paths in aerated CWs, thereby influencing the removal of pollutants, especially organics and nitrogen, which offers a reference for the design of aerated CWs. PMID:26360599

  5. Modeling of mixing for stirred bioreactors: 3. Mixing time for aerated simulated broths

    OpenAIRE

    Cascaval Dan; Oniscu Corneliu; Galaction Anca-Irina; Ungureanu Fiorina

    2002-01-01

    This paper presents the experiments on mixing efficiency for aerated media for a laboratory stirred bioreactor with a double turbine impeller. The effects of stirrer rotation speed, air volumetric flow rate and stirrer position on the shaft on mixing time for aerated water and simulated broths (CMCNa solutions) were analyzed. Compared to non-aerated broths, the results indicated that the variation of mixing time with the considered parameters is very different, due to the complex flow mechani...

  6. The Influence of Micropore Oxygen Aeration on the Pond Water Quality Environment

    OpenAIRE

    Xiao-Jiang Chen; Yun-Gan Zhu; Zi-Ming Zhao

    2013-01-01

    In order to know the effects of micropore oxygen aeration on the water quality and economic output, take each 3 of micropore oxygen aeration (experimental pond) and impeller oxygenation (control pond) to make the comparison, indexs of two different aeration methods water were detected from May, 2012 to October, 2012. Such as water temperature, dissolved oxygen, ammonia nitrogen and nitrite, phytoplankton, chemical oxygen demand (CODMn). Results showed that, (1) the indexes of the dissolved ox...

  7. Aeration for fouling control in Submerged Membrane Bioreactors for wastewater treatment: shear simulation and experimental validations

    OpenAIRE

    Braak, Etienne; Schetrite, Sylvie; Anne-Archard, Dominique; Albasi, Claire; Alliet-Gaubert, Marion

    2012-01-01

    Aeration for fouling prevention in SMBRs represents a great part of energy consumption of the process. To decrease it a better understanding of the impact of aeration on filtration performances is required. In spite of its beneficial effect (shear stress on membrane surface, turbulences...), the aeration has an impact on a potential destructuration of mixed liquor that could be detrimental to filtration. Our study aims at estimating this impact for SADm and SADp close to those used in full sc...

  8. Municipal wastewater treatment plant aeration systems and their comparison at WWTP Ljutomer and Murska Sobota

    OpenAIRE

    Kolbl, Sabina

    2009-01-01

    Graduation thesis discusses aeration systems at wastewater treatment plants (WWTP), and compares the operation of the WWTPs at Ljutomer and Murska Sobota. The first four chapters cover the theoretical fundamentals of WWTP aeration and aeration systems. In the introductory section of thesis, the biological treatment of wastewater and its basic processes are briefly discussed. According to the DVWK-ATV-A 131E standards, fundamental equations are discussed for both the rate of consumption and th...

  9. Influence of aeration intensity and medium acidity on phosphate mobilization affected by soil bacteria

    OpenAIRE

    K. V. Lavrentyeva; P. I. Kharchenko; N. V. Cherevach; A. I. Vinnikov

    2009-01-01

    The paper deals with the investigation of phosphate solubilisation conducted by two bacteria Pseudomonas putida and Enterobacter dissolvens under conditions of different rates of aeration and рН. Bacterial development was characterized by different media acidity and aeration levels. It was established optimal aeration rates and potential of hydrogen for soil bacteria growth and phosphate solubilisation – 0.5721 mole О2/l per hour and pH ≈ 6.0.

  10. Nitrogen removal in a Sequencing Batch Biofilm Reactor : effect of carbon availability and intermittent aeration

    OpenAIRE

    Vieira, Maria Madalena Costa; Brito, A. G.; R. Nogueira

    2009-01-01

    This study aimed to investigate the effects of carbon availability and intermittent aeration on nitrogen removal in a Sequencing Batch Biofilm Reactor (SBBR). The percentage of nitrogen removal in the SBBRs operating with dump fill and slow fill with optimum intermittent aeration was quite similar, 75.7% and 69.2%, respectively, indicating that intermittent aeration allowed a considerable energy saving without compromising significantly nitrogen removal. Accumulation of stor...

  11. Characteristics of aeration properties of selected soil profiles from central europe

    OpenAIRE

    Brzezińska M.; Włodarczyk T.; Stępniewska Z.; Stępniewski W.; Gliński J.

    2000-01-01

    The purpose of this paper was to characterise soil structure from the point of view of its aeration properties and to verify applicability of some methods for the determination of different properties related to aeration. The studies were performed on 15 representative soil samples from Austria, Czech Republic, Hungary, Poland and Slovakia. The paper presents results of measurements of different soil aeration properties such as oxygen diffusion rate (ODR), redox potential (Eh), relative gas d...

  12. Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast

    OpenAIRE

    Liu, Chen-Guang; Hao, Xue-Mi; Lin, Yen-Han; Bai, Feng-Wu

    2016-01-01

    Ethanol fermentation requires oxygen to maintain high biomass and cell viability, especially under very-high-gravity (VHG) condition. In this work, fermentation redox potential (ORP) was applied to drive the aeration process at low dissolved oxygen (DO) levels, which is infeasible to be regulated by a DO sensor. The performance and characteristics of flocculating yeast grown under 300 and 260 g glucose/L conditions were subjected to various aeration strategies including: no aeration; controll...

  13. Low-cost/low-technology aeration techniques for removing radon from drinking water. Environmental research brief

    International Nuclear Information System (INIS)

    Simple treatment techniques designed as low-cost/low-technology aeration techniques were investigated as to determine their effectiveness for the removal of radon from drinking water. The techniques investigated consisted of flow through storage and minimal aeration in various configurations and were found to be effective in varying degrees for the reduction of radon. These low-cost/low-technology aeration techniques may be easily applied in small communities

  14. Performance Evaluation of an Oxidation Ditch System with a Disc Aerator

    OpenAIRE

    Abdel E. Ghaly; Ashley Thistle

    2011-01-01

    Problem statement: The oxidation ditch system has been used to treat various types of wastewaters. Several types of aerators are used to supply the treatment process with oxygen. Among these devices, the disc aerator has certain advantages regarding foam generation over the brush and paddle type rotors, but the main disadvantages of this aerator is the limited oxygenation capacity. The main objectives of this study were to study the effects of various design parameters and system operation pa...

  15. Aeration-Induced Changes in Temperature and Nitrogen Dynamics in a Dimictic Lake.

    Science.gov (United States)

    Holmroos, Heidi; Horppila, Jukka; Laakso, Sanna; Niemistö, Juha; Hietanen, Susanna

    2016-07-01

    Low levels of oxygen (O) in the hypolimnion layer of lakes are harmful to benthic animals and fish; they may also adversely affect nutrient cycles. Artificial aeration is often used in lake management to counteract these problems, but the effects of aeration on nitrogen (N) cycling are not known. We studied the effects of hypolimnetic aeration on N dynamics and temperature in a eutrophic lake by comparing continuous and pulsed aeration with a nonaerated station. Aeration decreased the accumulation of NH-N deep in the lake (20-33 m) by supplying O for nitrification, which in turn provided substrate for denitrification and promoted N removal. Aeration also increased the temperature in the hypolimnion. Denitrification rate was highest in the nonaerated deep areas (average, 7.62 mg N m d) due to very high rates during spring turnover of the water column, demonstrating that natural turnover provides O for nitrification. During stratification, denitrification was highest at the continuously aerated station (4.06 mg N m d) and lowest at the nonaerated station (3.02 mg N m d). At the periodically aerated station, aeration pauses did not restrict the increase in temperature but resulted in accumulation of NH-N and decreased the contribution of denitrification as a nitrate reduction process. Our findings demonstrate that hypolimnetic aeration can substantially affect N cycling in lakes and that the effect depends on the aeration strategy. Because N is one of the main nutrients controlling eutrophication, the effects of aeration methods on N removal should be considered as part of strategies to manage water quality in lakes. PMID:27380085

  16. CFD study to determine the optimal configuration of aerators in a full-scale waste stabilization pond.

    Science.gov (United States)

    Alvarado, Andres; Vesvikar, Mehul; Cisneros, Juan F; Maere, Thomas; Goethals, Peter; Nopens, Ingmar

    2013-09-01

    Aerated lagoons (ALs) are important variants of the pond wastewater treatment technology that have not received much attention in the literature. The hydraulic behaviour of ALs and especially the Facultative aerated lagoons (FALs) is very complex since the aeration in these systems is designed for oxygen transfer but not necessarily to create complete mixing. In this work, the energy expenditure of the aerators was studied by means of a scenario analysis. 3D CFD models (one phase and multiphase) of a 3 ha FAL in a waste stabilization pond system in Cuenca (Ecuador) were built for different configurations of aerators. The thrust produced by the aerators was modelled by an external momentum source applied as velocity vectors into the pond fluid. The predictions of a single phase model were in satisfactory agreement with experimental results. Subsequently, a scenario analysis assessing several aeration schemes with different numbers of aerators in operation were tested with respect to velocity profiles and residence time distribution (RTD) curves. This analysis showed that the aeration scheme with all 10 aerators switched on produces a similar hydraulic behaviour compared to using only 6 or 8 aerators. The current operational schemes comprise of switching off some aerators during the peak hours of the day and operating all 10 aerators during night. This current practice could be economically replaced by continuously operating 4 or 6 aerators without significantly affecting the overall mixing. Furthermore, a continuous mixing regime minimises the sediment oxygen demand enhancing the oxygen levels in the pond. PMID:23764602

  17. The use of mechanical aeration and its effects on water mass

    Directory of Open Access Journals (Sweden)

    SIPAÚBA-TAVARES L. H.

    1999-01-01

    Full Text Available Due to the increasing use of artificial aerators in fish ponds, and to the lack of studies on this subject, this work studied some of the aspects associated with their use. The influence of a diffuser type aerator (AR 120 on the biotic and abiotic variables was evaluated in a fish pond. Three points of the pond were marked for the taking of samples: 5, 10 and 23 m from the aerator. Samples were taken every day for 15 consecutive days: 5 days before the use of the aerator, 5 days with the aerator functioning and 5 days with it not functioning. The limnological variables studied did not show significant differences (P > 0.05 when the three sampling points were compared, but regarding the use of the aerator, variables such as water temperature, transparency, pH, dissolved oxygen, bicarbonate, free CO2, total phosphorus, orthophosphate, ammonia nitrate and nitrite concentrations showed significant differences (P 0.05 with the use of the aerator regarding conductivity, alkalinity, total CO2 and chlorophyll a values. The phytoplanktonic community suffered as a direct influence of the aerator (P < 0.05. The community was dominated by Chlorophyta, representing more than 70% of the total organisms present, followed by Cyanophyta and Chrysophyta which tended to increase in number after the use of the aerator. This probably occurred because these groups adapt quickly to changes in the environment.

  18. Monitoring transitory profiles of leachate humic substances in landfill aeration reactors in mesophilic and thermophilic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Huanhuan [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Yin, Ke; Ge, Liya; Giannis, Apostolos [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); Chuan, Valerie W.L. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Wang, Jing-Yuan, E-mail: JYWANG@ntu.edu.sg [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2015-04-28

    Highlights: • Polymerization and condensation of humic substances (HS) were enhanced by aeration. • Carboxylic group was enriched in HS by aeration presenting improved hydrophilicity. • Mobility of humic acid, as a result was enhanced by aeration especially in young landfill. • Waste age plays an important role in leachate management during aeration. - Abstract: The presence of humic substances (HS) in landfill leachate is of great interest because of their structural stability and potential toxicity. This study examined the effects of temperature and waste age on the transformation of HS during in situ aeration of bioreactor landfills. By establishing aerobic conditions, dissolved organic carbon (DOC) rapidly accumulated in the bioreactor leachate. Fractional analysis showed that the elevated concentration of humic acids (HAs) was primarily responsible for the increment of leachate strength. Further structural characterization indicated that the molecular weight (MW) and aromacity of HS were enhanced by aeration in conjunction with thermophilic temperature. Interestingly, elevation of HAs concentration was not observed in the aeration reactor with a prolonged waste age, as the mobility of HAs was lowered by the high MW derived from extended waste age. Based on these results, aeration may be more favorable in aged landfills, since dissolution of HAs could be minimized by the evolution to larger MW compared to young landfills. Moreover, increased operation temperature during aeration likely offers benefits for the rapid maturation of HS.

  19. Microstructure and Properties of Silty Siliceous Crushed Stone-lime Aerated Concrete

    Institute of Scientific and Technical Information of China (English)

    WANG Qiankun; CHEN Youzhi; LI Fangxian; SUN Tao; XU Bingbo

    2006-01-01

    The clayish crushed stone was used for making aerated concrete. Through studying hydro-thermal synthesis reaction, mix ratio, gas-forming and performance analysis, Grade-B05 and Grade-B06 aerated concrete were prepared successfully. The proper mix ratio and key processing parameters were achieved. The microstructure of aerated concrete with crush stone was analyzed by means of XRD and SEM. The experimental results indicate that the hydration products are poorly crystalline C-S-H (B), tobermorite and hydrogarnet. No component of clay was found. Unreacted SiO2 can be in existence, and the structure system of aerated concrete is homogeneous and dense.

  20. Monitoring transitory profiles of leachate humic substances in landfill aeration reactors in mesophilic and thermophilic conditions

    International Nuclear Information System (INIS)

    Highlights: • Polymerization and condensation of humic substances (HS) were enhanced by aeration. • Carboxylic group was enriched in HS by aeration presenting improved hydrophilicity. • Mobility of humic acid, as a result was enhanced by aeration especially in young landfill. • Waste age plays an important role in leachate management during aeration. - Abstract: The presence of humic substances (HS) in landfill leachate is of great interest because of their structural stability and potential toxicity. This study examined the effects of temperature and waste age on the transformation of HS during in situ aeration of bioreactor landfills. By establishing aerobic conditions, dissolved organic carbon (DOC) rapidly accumulated in the bioreactor leachate. Fractional analysis showed that the elevated concentration of humic acids (HAs) was primarily responsible for the increment of leachate strength. Further structural characterization indicated that the molecular weight (MW) and aromacity of HS were enhanced by aeration in conjunction with thermophilic temperature. Interestingly, elevation of HAs concentration was not observed in the aeration reactor with a prolonged waste age, as the mobility of HAs was lowered by the high MW derived from extended waste age. Based on these results, aeration may be more favorable in aged landfills, since dissolution of HAs could be minimized by the evolution to larger MW compared to young landfills. Moreover, increased operation temperature during aeration likely offers benefits for the rapid maturation of HS

  1. The Effect of Air Hole Location For Aeration Performance in Circular Conduits

    OpenAIRE

    GÖKGÖZ, akın; GÜNEŞ, Muhammed Cemal; AKKOYUNLU, Yusuf; Ergün, Ömer; Ünsal, Mehmet

    2014-01-01

    Dissolved oxygen in the water is one of the important parameters that indicates water quality. İt is also important for aquatic life in water. Aeration methods used for increase theoxygen amount in waters.The injection of air from the atmosphere into water is called aeration. Hydroulic structures widely used in aeration. İn this study, the effect of air hole location to aeration percformance in circular conduits way investigated. As a result,there is no significant effect of air hole location...

  2. Bioreactor tests preliminary to landfill in situ aeration: A case study

    International Nuclear Information System (INIS)

    Highlights: ► Carbon and nitrogen mass balances in aerated landfill simulation reactors. ► Waste stabilization in aerated landfill simulation reactors. ► Effect of temperature on biodegradation processes in aerated landfills. - Abstract: Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45 °C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45 °C in the landfill. The results obtained showed positive effects of the aeration on leachate quality and a significant reduction of waste biodegradability. Although a delay of biodegradation processes was observed in the reactor run at 45 °C, biodegradation rates increased after 2 months of aeration, providing very low values of the relevant parameters (as in the other aerated reactors) by the end of the study. Mass balances were carried out for TOC and N-NH4+; the findings obtained were encouraging and provided evidence of the effectiveness of carbon and nitrogen conversion processes in the aerated landfill simulation reactors

  3. Bioreactor tests preliminary to landfill in situ aeration: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Raga, Roberto, E-mail: roberto.raga@unipd.it [ICEA Department, University of Padova. Via Marzolo, 9, 35131 Padova (Italy); Cossu, Raffaello [ICEA Department, University of Padova. Via Marzolo, 9, 35131 Padova (Italy)

    2013-04-15

    Highlights: ► Carbon and nitrogen mass balances in aerated landfill simulation reactors. ► Waste stabilization in aerated landfill simulation reactors. ► Effect of temperature on biodegradation processes in aerated landfills. - Abstract: Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45 °C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45 °C in the landfill. The results obtained showed positive effects of the aeration on leachate quality and a significant reduction of waste biodegradability. Although a delay of biodegradation processes was observed in the reactor run at 45 °C, biodegradation rates increased after 2 months of aeration, providing very low values of the relevant parameters (as in the other aerated reactors) by the end of the study. Mass balances were carried out for TOC and N-NH{sub 4}{sup +}; the findings obtained were encouraging and provided evidence of the effectiveness of carbon and nitrogen conversion processes in the aerated landfill simulation reactors.

  4. Landfill aeration in the framework of a reclamation project in Northern Italy.

    Science.gov (United States)

    Raga, Roberto; Cossu, Raffaello

    2014-03-01

    In situ aeration by means of the Airflow technology was proposed for landfill conditioning before landfill mining in the framework of a reclamation project in Northern Italy. A 1-year aeration project was carried out on part of the landfill with the objective of evaluating the effectiveness of the Airflow technology for landfill aerobization, the evolution of waste biological stability during aeration and the effects on leachate and biogas quality and emissions. The main outcomes of the 1-year aeration project are presented in the paper. The beneficial effect of the aeration on waste biological stability was clear (63% reduction of the respiration index); however, the effectiveness of aeration on the lower part of the landfill is questionable, due to the limited potential for air migration into the leachate saturated layers. During the 1-year in situ aeration project approx. 275 MgC were discharged from the landfill body with the extracted gas, corresponding to 4.6 gC/kgDM. However, due to the presence of anaerobic niches in the aerated landfill, approx. 46% of this amount was extracted as CH4, which is higher than reported in other aeration projects. The O2 conversion quota was lower than reported in other similar projects, mainly due to the higher air flow rates applied. The results obtained enabled valuable recommendations to be made for the subsequent application of the Airflow technology to the whole landfill. PMID:24411985

  5. Aeration aggressive radon waters in water supply management

    International Nuclear Information System (INIS)

    222Rn and CO2 must be removed in the treatment of drinking water. Three methods are suggested of the aeration of radon waters, where ceramic filter candles, frits, or filter heads are used. A comparison is made of the three methods and tabulated. Taking into account the technical aspects of water treatment and the effects of radiation on the oro.anism, a reduction in 222Rn content down to 5 to 10 Bq/l may be considered purposeful. (E.S.)

  6. DIGITAL IMAGE MEASUREMENT OF BUBBLE MOTION IN AERATED WATER FLOWS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Digital image measurement method, as an ex-tension of Particle Image Velocimetry of single-phase flowmeasurement, was investigated for application to air-watertwo-phase flows. The method has strong potential ability inmeasuring bubble geometrical features and moving velocitiesfor complex bubble motion in aerated water flow. Both dilutedand dense bubble rising flows are measured using the digitalimage method. Measured bubble shapes and sizes, and bubblevelocities are affected by threshold selection for binary image.Several algorithms for selecting threshold are compared andmethods for calculating the time-averaged void fraction arediscussed.

  7. Pulverizing aeration as a method of lakes restoration

    Science.gov (United States)

    Kaczorowska, E.; Podsiadłowski, S.

    2012-04-01

    The principal threat to lakes of the temperate zone is posed by factors accelerating their eutrophication and causing marked deoxygenation of the deeper layers of water, mainly the hypo- and metalimnion. Among their effects are frequent phytoplankton blooms, including those of blue-green algae, and general deterioration of water quality also affecting the abundance and health status of fish. The chief concern is a disturbed proportion between the amount of complex chemical compounds, especially organic, and the oxygen content of lake waters. Natural processes of water oxygenation are not too intensive, because they are practically limited to the epilimnion layer, connected as they are with the activity of aquatic plants of the littoral and sublittoral zone (which tends to disappear in contaminated lakes) and wind energy (the effect of waving). In summer conditions, with a relatively great chemical activity of bottom deposits, the intensity of those processes is usually inadequate. Hence, in 1995 a research was launched in the Institute of Agricultural Engineering of the Agricultural University in Poznań on an integrated lake restoration technology whose core was a self-powered aerator capable of oxygenating also the bottom layers of water (the hypolimnion) of deep lakes. The aerator uses energy obtained from a Savonius rotor mainly to diffuse gases: to release hydrogen sulphide, which usually saturates the hypolimnion water completely, and then to saturate this water with oxygen. Even early studies showed the constructed device to be highly efficient in improving oxygen conditions in the bottom zone. They also made it clear that it should be equipped with an autonomous system designed to inactivate phosphorus, one of the principal factors determining the rate of lake degradation. In 2003 the first wind-driven pulverising aerator equipped with such a system was installed in Town Lake in Chodzież. The aim of this work is to present the principles of operation of a

  8. Optimization of a production line of aerated concrete

    International Nuclear Information System (INIS)

    The process optimization of large-scale production plant for the manufacture of aerated concrete was performed by means of tracer techniques. The behaviour of all components which were labelled with short-lived radionuclides such as 18F, 24Na, 42K, 43Sc, and 140La were investigated both in a 3-chamber ball mill and in a wet mixer. Based on the results obtained the technological parameters of the production plant could be changed in order to increase the economical effectiveness. (author)

  9. The use of bottle caps as submerged aerated filter medium.

    Science.gov (United States)

    Damasceno de Oliveira, Laurence; Motlagh, Amir Mohaghegh; Goel, Ramesh; de Souza Missagia, Beatriz; Alves de Abreu Filho, Benício; Lautenschlager, Sandro Rogério

    2014-01-01

    In this study, a submerged aerated filter (SAF) using bottle caps as a support medium was evaluated. The system was fed with effluent from an upflow anaerobic sludge blanket system at ETE 2-South wastewater treatment plant, under different volumetric organic load rates (VOLRs). The population of a particular nitrifying microbial community was assessed by fluorescent in situ hybridization with specific oligonucleotide probes. The system showed an average removal of chemical oxygen demand (COD) equal to 76% for VOLRs between 2.6 and 13.6 kg COD m(-3)_media.day(-1). The process of nitrification in conjunction with the removal of organic matter was observed from applying VOLRs lower than 5.5 kg COD m(-3)_media.day(-1) resulting in 78% conversion of NH4(+)-N. As the applied organic load was reduced, an increase in the nitrifying bacteria population was observed compared with total 4'-6-diamidino-2-phenylindole (DAPI) stained cells. Generally, SAF using bottle caps as a biological aerated filter medium treating wastewater from an anaerobic system showed promising removal of chemical oxygen demand (COD) and conversion of NH4(+)-N. PMID:24718345

  10. 3D CT Imaging Method for Measuring Temporal Bone Aeration

    International Nuclear Information System (INIS)

    Objective: 3D volume reconstruction of CT images can be used to measure temporal bene aeration. This study evaluates the technique with respect to reproducibility and acquisition parameters. Material and methods: Helical CT images acquired from patients with radiographically normal temporal bones using standard clinical protocols were retrospectively analyzed. 3D image reconstruction was performed to measure the volume of air within the temporal bone. The appropriate threshold values for air were determined from reconstruction of a phantom with a known air volume imaged using the same clinical protocols. The appropriate air threshold values were applied to the clinical material. Results: Air volume was measured according to an acquisition algorithm. The average volume in the temporal bone CT group was 5.56 ml, compared to 5.19 ml in the head CT group (p = 0.59). The correlation coefficient between examiners was > 0.92. There was a wide range of aeration volumes among individual ears (0.76-18.84 ml); however, paired temporal bones differed by an average of just 1.11 ml. Conclusions: The method of volume measurement from 3D reconstruction reported here is widely available, easy to perform and produces consistent results among examiners. Application of the technique to archival CT data is possible using corrections for air segmentation thresholds according to acquisition parameters

  11. The Potential of Extended Aeration System for Sago Effluent Treatment

    Directory of Open Access Journals (Sweden)

    Wahi A. Rashid

    2010-01-01

    Full Text Available Problem statement: Sago effluent contains large amount of organic material which has a potential to cause water pollution. In order to reduce this problem, an experiment was conducted to remove organic material from sago effluent using lab scale of Extended Aeration (EA system. Approach: The EA system consisted of the combination of physical and biological treatment unit. For Physical Treatment Unit (PTU, the sago effluent was filtered using 710 µm mesh size filter. For Biological Treatment Unit (BTU, the effluent were mixed and aerated with activated sago sludge for 48 h. The treatment efficiency with respect to Biological Oxygen Demand (BOD, Chemical Oxygen Demand (COD and Total Suspended Solid (TSS removal were evaluated and compared with regulatory requirement by Department of Environment, Malaysia. Results: The result showed, the EA system could reduce BOD, COD and TSS up to 84, 87.8 and 73% respectively, however it did not comply with the regulatory requirement. Conclusion: This study suggested the EA system have potential to be apply on sago effluent, however it should be integrated with additional treatment unit to achieve the effluent quality standard.

  12. Experimental investigations of aeration efficiency in high-head gated circular conduits.

    Science.gov (United States)

    Cihat Tuna, M; Ozkan, Fahri; Baylar, Ahmet

    2014-01-01

    The primary purpose of water aeration is to increase the oxygen saturation of the water. This can be achieved by using hydraulic structures because of substantial air bubble entrainment at these structures. Closed conduit aeration is a particular instance of this. While there has been a great deal of research on air-demand ratio within closed conduit, very little research has specifically addressed aeration efficiency of closed conduit. In the present work an experimental study was conducted to investigate the aeration efficiency of high-head gated circular conduits. Results showed that high-head gated circular conduits were effective for oxygen transfer. The effects of Froude number and ratio of the water cross-sectional flow area to the conduit cross-sectional area on aeration efficiency were particularly significant, whereas the effect of conduit length was only moderate. Further, a design formula for the aeration efficiency was presented relating the aeration efficiency to ratio of water cross-sectional flow area to conduit cross-sectional area and Froude number. The obtained results will be useful in future modeling processes and aid the practicing engineer in predicting aeration efficiency for design purposes. PMID:24647194

  13. Biodegradation of diesel oil and gasoline contaminated effluent employing intermittent aeration.

    Science.gov (United States)

    Vieira, P A; Vieira, R B; Faria, S; Ribeiro, E J; Cardoso, V L

    2009-09-15

    We examined the effects of aeration interval and agitation speed in an effort to optimize the biodegradation of effluent contaminated with diesel oil and gasoline. The biodegradation process employed a C(1) mixed culture and intermittent aeration. Optimization was performed using central composite design (CCD). The independent variables were aeration interval (X(1)) and agitation speed (X(2)) and the dependent variable was the degree of removal of total petroleum hydrocarbons (TPH). The optimum aeration interval (33h) and agitation speed (110rpm) resulted in TPH removal of 75.9% after 3 days. Five hydrocarbons classes were identified using gas chromatography: paraffins, isoparaffins, olefins, naphthenics, and aromatics. The following reductions were observed: 91.8% for the paraffins, 83.3% for the isoparaffins, 80.9% for the olefins, 39.3% for the naphthenics, and 80.9% for the aromatics. In comparative studies performed under constant aeration (CA), without aeration (WA), and intermittent aeration (IA) conditions, intermittent aeration resulted in the highest TPH removals, with 90% reduction after 22 days. Under the IA condition, the degradation percentages were 99.6% for the paraffins, 94% for the isoparaffins, 95.4% for the olefins, 70.8 for the naphthenics, and 83.4% for the aromatics. PMID:19356851

  14. Evaluating aeration techniques for decreasing phosphorus export from grasslands receiving manure

    Science.gov (United States)

    Given that surface-applied manures can contribute to phosphorus (P) in runoff, a study was conducted to examine mechanical aeration of grasslands for reducing P transport by increasing infiltration of rainfall and binding of P with soil minerals. The effects of three aeration treatments and a contr...

  15. Aerated Shewanella oneidensis in Continuously-fed Bioelectrochemical Systems for Power and Hydrogen Production

    Science.gov (United States)

    We studied the effects of aeration of Shewanella oneidensis on potentiostatic current production, iron(III) reduction, hydrogen production in a microbial electrolysis cell, and electric power generation in a microbial fuel cell. The potentiostatic performance of aerated S. oneidensis was considerab...

  16. 40 CFR 265.278 - Unsaturated zone (zone of aeration) monitoring.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Unsaturated zone (zone of aeration) monitoring. 265.278 Section 265.278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED..., STORAGE, AND DISPOSAL FACILITIES Land Treatment § 265.278 Unsaturated zone (zone of aeration)...

  17. EXPERIMENTAL STUDY ON A NEW TYPE OF AERATOR IN SPILLWAY WITH LOW FROUDE NUMBER AND MILD SLOPE FLOW

    Institute of Scientific and Technical Information of China (English)

    SU Pei-lan; LIAO Hua-sheng; QIU Yue; LI Chen-juan

    2009-01-01

    Experimental study on aeration characteristics of various aeration devices was conducted in the spillway tunnel of the Pubugou hydropower project, Sichuan Province, China. It is shown by comparison that the new type of aeration device, namely, the aerator with a trapezoidal-shaped slot and a steep-slope section(ATSS), can avoid water accumulation in the cavity of the aeration device in the project, thus can effectively solve the backwater problems arising from this project and be used for a wide range of different water levels, without any drain facilities. Above the water level of 840 m, the water contained in the cavity can be eliminated completely, which means that the recommended new type of aerator can meet the aeration demands in the spillway of the project with low Froude number and may be of practical significance and of interest to other projects with similar types of aeration devices.

  18. Effects of intermittent aeration on pollutants removal in subsurface wastewater infiltration system.

    Science.gov (United States)

    Pan, Jing; Fei, Hexin; Song, Siyu; Yuan, Fang; Yu, Long

    2015-09-01

    In this study, the pollutant removal performances in two pilot-scale subsurface wastewater infiltration systems (SWISs) with and without intermittent aeration were investigated. Matrix oxidation reduction potential (ORP) results showed that intermittent aeration well developed aerobic conditions in upper matrix and anoxic or anaerobic conditions in the subsequent sections, which resulted in high NH4(+)-N and TN removal. Moreover, intermittent aeration increased removal rates of COD and TP. Microbial populations and enzyme activities analysis proved that intermittent aeration not only obviously boosted the growth and reproduction of bacteria, fungus, actinomyces, nitrifying bacteria and denitrifying bacteria, but also successfully increased nitrate reductase (NR) and nitrite reductase (NIR) in the depth of 80 and 110 cm. The results suggest that the intermittent aeration could be a widespread research and application strategy for achieving the high removal performance in SWISs. PMID:26004389

  19. Nitrous oxide emissions from an intermittent aeration activated sludge system of an urban wastewater treatment plant

    Directory of Open Access Journals (Sweden)

    William Z. de Mello

    2013-01-01

    Full Text Available This study investigated the emission of N2O during the sequential aerated (60-min and non-aerated (30-min stages of an intermittent aeration cycle in an activated sludge wastewater treatment plant (WWTP. N2O emission occurred during both stages; however, emission was much higher during aeration. Air stripping is the major factor controlling transfer of N2O from the sewage to the atmosphere. The N2O emissions exclusively from the aeration tank represented 0.10% of the influent total nitrogen load and the per capita emission factor was almost 3 times higher than that suggested by the IPCC for inventories of N2O emission from WWTPs.

  20. EXPERIMENTAL INVESTIGATION ON SOUND SPEED PROPAGATING THROUGH HIGH SPEED AERATED FLOW IN OPEN CHANNEL

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experiment concerning the sound propaga-tion in aerated open channel flow was designed and conductedin a variable slope chute. The acquisition of sound data wasdone by the hydro-phones installed into the bottom wall of thechute. The data were analyzed and processed by the tape re-corder and a 3562A analyzer. The primary experimetal resultsindicated that the sound speed in aerated flow is varied with the air concentration and highly lower than each of the soundspeed in pure water or air. As released by the derived theoryformula, the minimum sound of 24m/s in aerated flow hap-pened when the air concentration achieved to 50%. This resultshows that the compressibility of high speed aerated flowshould be considered when the air concentration is near to50%. A criterion of compressibility of high speed aerated flowwas also giv. En in this paper.

  1. Influence of the waste oil concentration in water on the efficiency of the aeration process in refinery wastewater treatment:

    OpenAIRE

    PAVLOVIĆ, Milan; Simić, Stojan N.; Stanojević, Miroslav; Ševaljević, Mirjana

    2008-01-01

    Process, aeration system and aeration method for biological treatment of wastewater with activated sludge in bio-aeration tanks are chosen based on theflow parameters, composition of the wastewater and required characteristicsof the purified water. Choosing an aeration system is a very complex question, as the capacity of oxygen introduced into the wastewater should correspond to the oxygen consumption in order to achieve the most efficient purification. This paper presents the results of exp...

  2. Impact of aeration control on N2O emission in a full-scale activated sludge wastewater treatment plant

    OpenAIRE

    Filali, A.; Fayolle, Y.; Peu, P.; Philippe, L.; Nauleau, F.; Gillot, S.

    2013-01-01

    International audience This work investigated the impact of aeration control strategy on energy consumption and nitrous oxide (N2O) emission in a full-scale wastewater treatment plant. Two identical activated sludge processes treating the same effluent but operated with different aeration control strategies were compared. Aeration tank 1 was operated with a new control strategy favouring the simultaneous nitrification denitrification (SND) whereas aeration tank 2 was operated with a conven...

  3. Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

    International Nuclear Information System (INIS)

    The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM

  4. Aeration-Controlled Formation of Acid in Heterolactic Fermentations

    DEFF Research Database (Denmark)

    Adler-Nissen, Jens

    1994-01-01

    Controlled aeration of Leuconostoc mesenteroides was studied as a possible mechanism for control of the formation of acetic acid, a metabolite of major influence on the taste of lactic fermented foods. Fermentations were carried out in small scale in a medium in which growth was limited by the...... buffer capacity only. Ethanol and acetic acid formed during the fermentation were analyzed by rapid head space gas chromatography, and the ratio of the molar concentrations of these two volatiles quantitatively predicted the balance between the formation of acetic acid and lactic acid. The oxygen...... concentration during the fermentations decreased rapidly to zero, meaning that oxygen transfer was limited by the volumetric oxygen transfer rate, k1aC*. A linear correlation between k1aC* and the quantity of acetic acid produced was established, and it is suggested that such oxygenated heterolactic...

  5. DOMESTIC WASTEWATER PURIFICATION IN UPFLOW BIOFILM SYSTEM WITH DIFFUSED AERATION

    Directory of Open Access Journals (Sweden)

    A.Mesdaghinia

    1984-08-01

    Full Text Available The objective of this research was to conduct a bench scale study of fixed activated sludge treating domestic sewage. Two different units employing diffused aeration with plastic and aluminum media were studied in four separate phases. Data indicated that the system could produce a high quality effluent without any requirements for sludge recycling through the system. Suspended solids concentrations of 3-6 mg/1, BOD5 concentrations of 4-12 mg/1 and COD concentrations of 35-45 mg/1 were found in the effluent with wastewater retentions ranging from 3-15 hours, whereas an indication of nitrification was observed in higher detention periods. As far as the type of media was concerned, the plastic and aluminum media did not differ significantly once the microbes had grown on the media.

  6. Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ferretti, D., E-mail: daniele.ferretti@unipr.it [Department of Civil, Environmental, Land Management Engineering and Architecture, University of Parma, P.co Area delle Scienze 181/A, 43124 Parma (Italy); Michelini, E. [Department of Civil, Environmental, Land Management Engineering and Architecture, University of Parma, P.co Area delle Scienze 181/A, 43124 Parma (Italy); Rosati, G. [Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano (Italy)

    2015-01-15

    The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM.

  7. Modeling of damage due to shrinkage in autoclaved aerated concrete

    Czech Academy of Sciences Publication Activity Database

    Koudelka, T.; Kruis, J.; Sysala, Stanislav; Vokáč, M.

    Vol. 1648. Melville, NY: AIP Publishing, 2015 - (Simos, T.; Tsitouras, C.), 090012-1-090012-4. (AIP Conference Proceedings. 1648). ISBN 978-0-7354-1287-3. ISSN 0094-243X. [International Conference on Numerical Analysis and Applied Mathematics 2014 (ICNAAM-2014). Rhodes (GR), 22.09.2014-28.09.2014] R&D Projects: GA ČR GA13-18652S Institutional support: RVO:68145535 Keywords : autoclaved aerated concrete * isotropic damage * shrinkage * coupled problems Subject RIV: JM - Building Engineering http://scitation.aip.org/docserver/fulltext/aip/proceeding/aipcp/1648/10.1063/1.4912400/1.4912400.pdf?expires=1427792299&id=id&accname=guest&checksum=6AE655B2B43B3EDCD5D3CA15B4C56CB7

  8. Internal aeration development and the zonation of plants in wetlands

    DEFF Research Database (Denmark)

    Sorrell, Brian Keith

    Permanent and indefinite survival of plants in flooded soils depends primarily on adaptations that increase the supply of oxygen to tissues in anoxic soil and water, usually associated with features such as (i) increased tissue porosity, (ii) changes in tissue permeability to gases, and (iii...... support many species which have root aeration adaptations but are otherwise unspecialised for aquatic life. Permanent standing water is a much greater challenge for plants, and survival here is restricted to species with special adaptations to their oxygen transport physiology such as the development...... differing in flooding tolerance. Maintaining species diversity in managed wetlands therefore involves hydrological conditions suitable for a variety of plants that differ in their flooding tolerance. The shallowest areas of wetlands, in which soils are waterlogged but there is little standing water, can...

  9. Nitrogen and phosphorus removal under intermittent aeration conditions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A practice wastewater treatment plant was operated usingintermittent aeration activated sludge process to enhancebiological nitrogen and phosphorus removal. When the influentconcentrations of CODCr, BOD5, TN, TP, NH3-N, TKN, and SS varied ina range of 207.5-1640 mg/L, 61.8-637 mg/L, 28.5-75.6 mg/L, 4.38-20.2 mg/L, 13.6-31.9 mg/L, 28.5-75.6 mg/L, and 111-1208 mg/L, theeffluent means were less than 50 mg/L, 20 mg/L, 5 mg/L, 1.0 mg/L,5 mg/L, 10 mg/L, and 20 mg/L, respectively. Based on a long time ofoperating results, this process is very suitable for nutrientbiological removal for treating the municipal wastewater thosewater characteristics are similar as that of the Songjiang Municipal Waste water Treatment plant(SJMWTP).

  10. Optimization of aeration for biodiesel production by Scenedesmus obliquus grown in municipal wastewater.

    Science.gov (United States)

    Han, Song-Fang; Jin, Wenbiao; Tu, Renjie; Abomohra, Abd El-Fatah; Wang, Zhi-Han

    2016-07-01

    Despite the significant breakthroughs in research on microalgae as a feedstock for biodiesel, its production cost is still much higher than that of fossil diesel. One possible solution to overcome this problem is to optimize algal growth and lipid production in wastewater. The present study examines the optimization of pretreatment of municipal wastewater and aeration conditions in order to enhance the lipid productivity of Scenedesmus obliquus. Results showed that no significant differences were recorded in lipid productivity of S. obliquus grown in primary settled or sterilized municipal wastewater; however, ultrasound pretreatment of wastewater significantly decreased the lipid production. Whereas, aeration rates of 0.2 vvm significantly increased lipid content by 51 %, with respect to the non-aerated culture, which resulted in maximum lipid productivity (32.5 mg L(-1) day(-1)). Furthermore, aeration enrichment by 2 % CO2 resulted in increase of lipid productivity by 46 % over the CO2 non-enriched aerated culture. Fatty acid profile showed that optimized aeration significantly enhanced monounsaturated fatty acid production, composed mainly of C18:1, by 1.8 times over the non-aerated S. obliquus culture with insignificant changes in polyunsaturated fatty acid proportion; suggesting better biodiesel characteristics for the optimized culture. PMID:26969589

  11. The importance of aeration strategy in fuel alcohol fermentations contaminated with Dekkera/Brettanomyces yeasts.

    Science.gov (United States)

    Abbott, D A; Ingledew, W M

    2005-11-01

    Whole corn mash fermentations infected with industrially-isolated Brettanomyces yeasts were not affected even when viable Brettanomyces yeasts out-numbered Saccharomyces yeasts tenfold at the onset of fermentation. Therefore, aeration, a parameter that is pivotal to the physiology of Dekkera/Brettanomyces yeasts, was investigated in mixed culture fermentations. Results suggest that aeration strategy plays a significant role in Dekkera/Brettanomyces-mediated inhibition of fuel alcohol fermentations. Although growth of Saccharomyces cerevisiae was not impeded, mixed culture fermentations aerated at rates of > or =20 ml air l(-1) mash min(-1) showed decreased ethanol yields and an accumulation of acetic acid. The importance of aeration was examined further in combination with organic acid(s). Growth of Saccharomyces occurred more rapidly than growth of Brettanomyces yeasts in all conditions. The combination of 0.075% (w/v) acetic acid and contamination with Brettanomyces TK 1404W did not negatively impact the final ethanol yield under fermentative conditions. Aeration, however, did prove to be detrimental to final ethanol yields. With the inclusion of aeration in the control condition (no organic acid stress) and in each fermentation containing organic acid(s), the final ethanol yields were decreased. It was therefore concluded that aeration strategy is the key parameter in regards to the negative effects observed in fuel alcohol fermentations infected with Dekkera/Brettanomyces yeasts. PMID:15782293

  12. Composting of tobacco plant waste by manual turning and forced aeration system

    Directory of Open Access Journals (Sweden)

    Nonglak Saithep

    2009-05-01

    Full Text Available The efficiency of tobacco plant waste composting, by the manual turning and the forced aeration system, was compared. Tobacco plant waste, cow manure, urea fertiliser, and a compost inoculum mixture at a 100:10:0.2:0.01 ratio respectively, with 60% (w/v moisture content, were set up in piling forms. The piles of the manual turning system were provided with turning aeration by hand at intervals of 7 days during the composting process. For the forced aeration system, each pile was aerated by a 3-HP air pump with a flow rate of 19 litres min-1 for 15 minutes every morning and evening. The completely randomised design of turned and force-aerated piles was performed in triplicate. The composting activity of both systems during the composting period was measured by several parameters: temperature, pH, moisture content, C/N ratio, growth of microorganisms, cellulase activity, and nicotine degradation in the set-up piles. Both systems had similar temperature, pH, and moisture content conditions in the piles during the composting process. However, the forced aeration system was more advantageous for the growth of mesophilic and thermophilic microorganisms, for cellulase activity from cellulase-producing microorganisms, and for nicotine degradation, when compared to the manual turning system. In conclusion, the forced aeration system was more efficient than the manual turning system in composting and is a viable alternative method for the composting process.

  13. [Removal nitrogen of integrated vertical-flow constructed wetland under aeration condition].

    Science.gov (United States)

    Tao, Min; He, Feng; Xu, Dong; Zhou, Qiao-Hong; Liang, Wei; Chen, Shui-Ping; Wu, Zhen-Bin

    2011-03-01

    Oxygen is an important limit factor of nitrogen removal in constructed wetlands, so it is the key point for improving nitrogen removal efficiency of constructed wetlands that the optimization of oxygen distribution within wetlands. Therefore, oxygen status, nitrogen removal and purification mechanism of integrated vertical-flow constructed wetland (IVCW) under aeration condition in summer and winter have been studied. The results showed that both oxygen levels and aerobic zones were increased in the wetland substrates. The area of oxic zone I (expressing with depth) extended from 22 cm, 17 cm to 53 cm, 44 cm, in summer and winter, respectively. The electric potential (Eh) profiling demonstrated that artificial aeration maintained the pattern of sequential oxic-anoxic-oxic (O-A-O) redox zones within the aerated IVCW in winter, while only two oxic-anoxic (O-A) zones were present inside the non-aerated IVCW in the cold season. The decomposition of organic matter and nitrification were obviously enhanced by artificial aeration since the removal efficiency of COD, TN and NH4(+) -N were increased by 12.2%, 6.9% and 15.1% in winter, respectively. There was no significant accumulation of NO3(-) -N in the effluent with an aeration cycle of 8 h on and 16 h off in this experiment. Moreover, we found that oxic zone I was the main region of pollutants removal in IVCW system, and artificial aeration mainly acted to enhance the purification capacity of this oxic zone in the aerated IVCW. These results suggest that aeration is important for optimization and application of IVCW system. PMID:21634169

  14. Aeration of the teuftal landfill: Field scale concept and lab scale simulation.

    Science.gov (United States)

    Ritzkowski, Marco; Walker, Beat; Kuchta, Kerstin; Raga, Roberto; Stegmann, Rainer

    2016-09-01

    Long lasting post-closure care (PCC) is often the major financial burden for operators of municipal solid waste (MSW) landfills. Beside costs for the installation and maintenance of technical equipment and barriers, in particular long term treatment of leachate and landfill gas has to be paid from capital surplus. Estimations based on laboratory experiments project time periods of many decades until leachate quality allows for direct discharge (i.e. no need for further purification). Projections based on leachate samples derived from the last 37years for 35 German landfills confirm these assumption. Moreover, the data illustrate that in particular ammonium nitrogen concentrations are likely to fall below limit values only after a period of 300years. In order to avoid long lasting PCC the operator of Teuftal landfill, located in the Swiss canton Bern, decided to biologically stabilize the landfill by means of a combined in situ aeration and moisturization approach. In December 2014 the aeration started at a landfill section containing approximately 30% of the total landfill volume. From summer 2016 onwards the remaining part of the landfill will be aerated. Landfill aeration through horizontal gas and leachate drains is carried out for the first time in field scale in Europe. The technical concept is described in the paper. Parallel to field scale aeration, investigations for the carbon and nitrogen turnover are carried out by means of both simulated aerated landfills and simulated anaerobic landfills. The results presented in this paper demonstrate that aeration is capable to enhance, both carbon mobilization and discharge via the gas phase. This effect comes along with a significant increase in bio-stabilization of the waste organic fraction, which positively affects the landfill emission behavior in the long run. In terms of leachate pollution reduction it could be demonstrated that the organic load decrease fast and widely independent of the adjusted aeration

  15. Performance Evaluation of an Oxidation Ditch System with a Disc Aerator

    Directory of Open Access Journals (Sweden)

    Abdel E. Ghaly

    2011-01-01

    Full Text Available Problem statement: The oxidation ditch system has been used to treat various types of wastewaters. Several types of aerators are used to supply the treatment process with oxygen. Among these devices, the disc aerator has certain advantages regarding foam generation over the brush and paddle type rotors, but the main disadvantages of this aerator is the limited oxygenation capacity. The main objectives of this study were to study the effects of various design parameters and system operation parameters on the oxygenation capacity of the system. Approach: A bench scale oxidation ditch system equipped with a disc aerator was used to gain better understanding of the phenomena of oxygen transfer and to study the effects of hole diameter, number of holes per disc, disc thickness, disc speed, immersion depth and number of discs on the oxygenation capacity of the system. The unsteady state method with sulphite oxidation was used to deoxygenate the water. The test involved chemical removal of dissolved oxygen from water followed by oxygenation. The power consumed was measured, the oxygen transfer coefficient was determined and both the oxygenation capacity and oxygenation efficiency were calculated. Results: The oxygen transfer coefficient was affected by the immersion depth, hole diameter, disc speed, disc thickness and number of discs, with the disc speed having the greatest effect. The results showed that three physical processes simultaneously contributed to oxygen transfer by the disc aerator: bubble aeration, eddy aeration and surface aeration. Conclusion: The use of sodium sulphite with cobalt chloride for deoxygenation of the water via the oxidation ditch was effective and the results were very consistent and repeatable. The aerator disc of 2.55 cm thickness, 1.92 cm diameter and 48 holes was found to achieve the highest oxygenation capacity. The system is anticipated to provide a broad range of oxygen transfer rates under actual conditions (23

  16. Alteration of Iron Level in Drinking Water by Aeration in Gonbad Kavoos (North East of Iran)

    OpenAIRE

    Abdoljalal Marjani; Abdoljabbar Nazari; Mostefa Seyyed

    2009-01-01

    Problem statement: In this study, removal of iron was surveyed in well water in Gonbad Kavoos City. Approach: Samples were taken before and after aeration. Concentration of iron in each sample was measured by spectrophotometer. Results: The results showed that the iron concentration was decreased after aeration (0.55, 0.44, 0.44, 0.46, 0.40 and 0.41 mg L-1) when compared with before aeration of water (0.64, 0.68, 0.65, 0.62, 0.65 and 0.67 mg L-1), respectiv...

  17. USING AERATION FOR RECARBONATION OF WATER AFTER SOFTENING BY LIME-SODA ASH

    OpenAIRE

    Laith A. Al Anaz

    2013-01-01

    Theresearch focus on using the aeration process as means for water recarbonationafter lime-soda softening. The results indicated that aeration efficientfor  recarbonation of three water sampleswith different characteristics. The lime-soda softening increased the (pH)values of the three samples to  reach(10.08,10.39,10.54) respectively. The aeration decreased these (pH) values to(8.26,8.36,8.23) respectively within (60)minutes. The depression was related tothe convert of the hydroxide and carb...

  18. Aeration effect on Spirulina platensis growth and γ-linolenic acid production

    OpenAIRE

    Srinivasa Reddy Ronda; Chandra Sekhar Bokka; Chandrika Ketineni; Binod Rijal; Prasada Rao Allu

    2012-01-01

    The influence of aeration on algal growth and gamma-linolenic acid (GLA) production in a bubble column photobioreactor was investigated. Studies were performed in a 20-L reactor at different aeration rates (0.2– 2.5 vvm). Static, continuous, and periodic operation of air resulted in 41.9%, 88.4%, and 108% air saturation of dissolved oxygen, for which the corresponding values of GLA were 2.3, 6.5, and 7.5 mg·g-1 dry cell weight, respectively. An increase in the aeration rate from 0.2 to 2.5 vv...

  19. Improved Aeration Process - Catalytic Role Of The Iron Oxides In Arsenic Oxidation And Coprecipitation

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Søgaard, Erik Gydesen

    2013-01-01

    improved aeration process that can also help in developing better arsenic removal treatment. The results present advantages of arsenic oxidation in an aeration process in the presence of ferrihydrite surface that have been shown to adsorb arsenic simultaneously to its oxidation. The presence of...... aeration. Moreover, it was found that the adsorption rate was limited by an excess of dissolved iron, due to competition between arsenic and iron compounds for adsorption sites on iron oxyhydroxide surface. The results were obtained both in lab and pilot scale experiments, which enabled to illustrate...

  20. Computational Fluid Dynamics Modelling of Hydraulics and Sedimentation in Process Reactors during Aeration Tank Settling

    DEFF Research Database (Denmark)

    Jensen, M.D.; Ingildsen, P.; Rasmussen, Michael R.;

    2006-01-01

    Aeration tank settling is a control method allowing settling in the process tank during highhydraulic load. The control method is patented. Aeration tank settling has been applied in several wastewater treatment plants using the present design of the process tanks. Some process tank designs...... and outletcausing a disruption of the sludge blanket at the outlet and thereby reducing the retention of sludge in theprocess tank. The model has allowed us to establish a clear picture of the problems arising at the plantduring aeration tank settling. Secondly, several process tank design changes...

  1. Computational Fluid Dynamics Modelling of Hydraulics and Sedimentation in Process Reactors During Aeration Tank Settling

    DEFF Research Database (Denmark)

    Dam Jensen, Mette; Ingildsen, Pernille; Rasmussen, Michael R.;

    2005-01-01

    Aeration Tank Settling is a control method alowing settling in the process tank during high hydraulic load. The control method is patented. Aeration Tank Settling has been applied in several waste water treatment plant's using present design of the process tanks. Some process tank designs have...... and outlet causing a disruption of the sludge blanket at the outlet and thereby reducing the retention of sludge in the process tank. The model has allowed us to establish a clear picture of the problems arising at the plant during Aeration Tank Settling. Secondly, several process tank design changes...

  2. NUMERICAL SIMULATION OF 3-D AERATED JET BEHIND FLIP BUCKET OF OVERFLOW DAM

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Aerated jet,such as the jet flow behind the flip bucket of an overflow dam, widely exists in hydraulic engineering. Up to now the model test and prototype observation have been two main methods of studying the aerated jet for a special hydraulic project. In this paper, a three-dimensional mathematical model for the aerated jet was established. It seems that the suggested model has high predictive power by comparison with the results of model tests and prototype observations, which is very useful in the study of energy dissipation and jet flow atomization.

  3. AN INVESTIGATION OF FLOW CHARACTERISTIC OF AERATED DRAG REDUCTION IN TUBE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Under the aerated conditions of wall and top intube, the turbulent flow in the tube was measured by usingLDA. The turbulent structure of the flow field and the mech-anism of aerating drag reduction in the tube were discussed. It is shown that the energy dissipations of turbulence flow andmean flow will reduce and the flow velocity (or flow rate) willincrease by injecting mini-bubbles to the wall or top of tube,namely the effect of aerating drag reduction is attained.

  4. Numerical modelling of the strength of highly porous aerated autoclaved concrete

    Energy Technology Data Exchange (ETDEWEB)

    Schenider, T.; Greil, P. [Univ. of Erlangen-Nuernberg, Erlangen (Germany). Dept. of Materials Science; Schober, G. [Hebel AG, Fuerstenfeldbruck (Germany). Materialtechnische Entwicklung

    1998-12-31

    Highly porous building materials like aerated autoclaved concrete are characterized by low thermal conductivity and high mechanical strength, which both strongly depend on porosity. The influence of porosity distribution on the compressive strength of aerated autoclaved concrete was investigated by using finite element analysis and multiaxial Weibull theory. Calculations of failure probability of microstructures with ordered as well as random pore configurations show a dependence of compressive strength on the Weibull modulus of the matrix material and the size and arrangement of pores. The results of the calculations are compared to experimental data of aerated autoclaved concrete.

  5. Improving microalgal growth with reduced diameters of aeration bubbles and enhanced mass transfer of solution in an oscillating flow field.

    Science.gov (United States)

    Yang, Zongbo; Cheng, Jun; Lin, Richen; Zhou, Junhu; Cen, Kefa

    2016-07-01

    A novel oscillating gas aerator combined with an oscillating baffle was proposed to generate smaller aeration bubbles and enhance solution mass transfer, which can improve microalgal growth in a raceway pond. A high-speed photography system (HSP) was used to measure bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure mass-transfer coefficient and mixing time. Bubble diameter and generation time decreased with decreased aeration gas rate, decreased orifice diameter, and increased water velocity in the oscillating gas aerator. The optimized oscillating gas aerator decreased bubble diameter and generation time by 25% and 58%, respectively, compared with a horizontal tubular gas aerator. Using an oscillating gas aerator and an oscillating baffle in a raceway pond increased the solution mass-transfer coefficient by 15% and decreased mixing time by 32%; consequently, microalgal biomass yield increased by 19%. PMID:27035474

  6. Enhanced long-term organics and nitrogen removal and associated microbial community in intermittently aerated subsurface flow constructed wetlands.

    Science.gov (United States)

    Fan, Jinlin; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Wu, Haiming

    2016-08-01

    The long-term enhanced removal efficiency of organics and nitrogen in subsurface flow constructed wetlands (SSF CWs) with and without intermittent aeration for decentralized domestic wastewater was evaluated, and the function of intermittent aeration on microbial community was also investigated in this study. The high and long-term 95.6% COD, 96.1% NH4(+)-N and 85.8% TN removal efficiencies were achieved in experimental intermittently aerated SSF CW compared with non-aerated SSF CW. Aerated SSF CWs also exhibited the excellent removal performance when comparatively comparing with other strategies and techniques applied in CWs. In addition, fluorescence in situ hybridization (FISH) analysis revealed that associated microbial abundance significantly increased owing to intermittent aeration. These results indicated intermittent aeration CWs might be an effective and sustainable strategy for wastewater treatment in rural areas, but require further full-scale investigation in future. PMID:27246456

  7. Removal of radon by aeration: testing of various aeration techniques for small water works. For European Commission under Contract No FI4PCT960054 TENAWA project

    Energy Technology Data Exchange (ETDEWEB)

    Salonen, L.; Mehtonen, J. [Radiation and Nuclear Safety Authority, Helsinki (Finland); Turunen, H. [Vartiainen Oy, Water Engineering Company (Finland); Mjoenes, L.; Hagberg, N. [SSI, Swedish Radiation Protection Institute (Sweden); Raff, O. [ESWE, Institute of Water Research and Water Technology (Germany)

    2002-12-01

    Capability of various aeration techniques to remove radon from water in small waterworks was studied as a part of project (Treatment Techniques for Removing Natural Radionuclides from Drinking Water), which was carried out during 1997-1999 on a cost-shared basis (contract No. F14PCT960054) with The European Commission (CEC) under the supervision of the Directorate-General XII Radiation Protection Research Unit. In TENAWA project both laboratory and field experiments were performed in order to find reliable methods and equipment for removing natural radionuclides from ground water originating either from private wells or small waterworks. Because such techniques are more often needed in private households than at waterworks, the main emphasis of the research was aimed to solve the water treatment problems related to the private water supplies, especially bedrock wells. Radon was the most important radionuclide to be removed from water at waterworks whereas the removal of other radionuclides ({sup 234,238}U, {sup 226,228}Ra, {sup 210}Pb and {sup 210}Po) was oft required from radonrich bedrock waters. The currently available methods and equipment were mainly tested during the field and laboratory experiments but the project was also aimed to find new materials, absorbents and membranes applicable for radionuclide removal from various types of ground waters (e.g. soft, hard, acidic). Because iron, manganese or organic occur in waters with radionuclides, their simultaneous removal was also studied. The project was divided into 13 work packages. In this report the results of the work package 2.2 are described. Elevated levels of radon and other natural radionuclides in European ground waters have been observed mainly in wide areas of the crystalline Scandinavian bedrock, especially in the granite rock areas of Finland and Sweden but also in more limited crystalline rock areas of Central and Southern Europe, Ukraine and Scotland. The radon removal efficiencies of

  8. Removal of radon by aeration: testing of various aeration techniques for small water works. For European Commission under Contract No FI4PCT960054 TENAWA project

    International Nuclear Information System (INIS)

    Capability of various aeration techniques to remove radon from water in small waterworks was studied as a part of project (Treatment Techniques for Removing Natural Radionuclides from Drinking Water), which was carried out during 1997-1999 on a cost-shared basis (contract No. F14PCT960054) with The European Commission (CEC) under the supervision of the Directorate-General XII Radiation Protection Research Unit. In TENAWA project both laboratory and field experiments were performed in order to find reliable methods and equipment for removing natural radionuclides from ground water originating either from private wells or small waterworks. Because such techniques are more often needed in private households than at waterworks, the main emphasis of the research was aimed to solve the water treatment problems related to the private water supplies, especially bedrock wells. Radon was the most important radionuclide to be removed from water at waterworks whereas the removal of other radionuclides (234,238U, 226,228Ra, 210Pb and 210Po) was oft required from radonrich bedrock waters. The currently available methods and equipment were mainly tested during the field and laboratory experiments but the project was also aimed to find new materials, absorbents and membranes applicable for radionuclide removal from various types of ground waters (e.g. soft, hard, acidic). Because iron, manganese or organic occur in waters with radionuclides, their simultaneous removal was also studied. The project was divided into 13 work packages. In this report the results of the work package 2.2 are described. Elevated levels of radon and other natural radionuclides in European ground waters have been observed mainly in wide areas of the crystalline Scandinavian bedrock, especially in the granite rock areas of Finland and Sweden but also in more limited crystalline rock areas of Central and Southern Europe, Ukraine and Scotland. The radon removal efficiencies of different aeration methods

  9. Research on factors influencing radon exhalation rate on aerated concrete block

    International Nuclear Information System (INIS)

    The research was carried out on the variation of the radon exhalation rate of aerated concrete block with the water content and dimension by using the RAD7 radon monitor and the radon exhalation rate test cabin of building materials. The result indicates that the amount of the same samples has no influence on the samples' radon exhalation; if the volume of the aerated concrete block in the test cabin is unchanged and the surface area increases, the radon exhalation rate decreases, but the total of the radon exhaling from the surface of the aerated concrete block keeps constant; for the aerated concrete block, its radon exhalation rate increases with water content as logarithmic growth. (authors)

  10. Effects of impeller speed and aeration rate on flotation performance of sulphide ore

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effects of aeration rate and impeller speed on the concentrate sulfur grade and recovery for batch flotation of a complex sulphide ore were investigated. The relationships between the water recovery and solid entrainment were discussed. It is found that the solid entrainment is linearly related to the water recovery regardless of aeration rate and impeller speed, and the higher sulfur recovery at the aeration rate of 2 and 4 L/min for the impeller speed of 1 500 r/min is considered to be the contribution of true flotation. Finally, the sulfur recovery flux is correlated with the bubble surface area flux based on the froth image at the different aeration rates and impeller speeds.

  11. Improving microalgal growth with small bubbles in a raceway pond with swing gas aerators.

    Science.gov (United States)

    Yang, Zongbo; Cheng, Jun; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2016-09-01

    A novel swing gas aerator was developed to generate small bubbles for improving the mass transfer coefficient and microalgal growth rate in a raceway pond. A high-speed photography system (HSP) was used to measure the bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure the mass transfer coefficient and mixing time. Bubble generation time and diameter decreased by 21% and 9%, respectively, when rubber gas aerators were swung in the microalgae solution. When water pump power and gas aeration rate increased in a raceway pond with swing gas aerators and oscillating baffles (SGAOB), bubble generation time and diameter decreased but solution velocity and mass transfer coefficient increased. The mass transfer coefficient increased by 25% and the solution velocity increased by 11% when SGAOB was used, and the microalgal biomass yield increased by 18%. PMID:27243604

  12. SONIC SPEED AND SHOCK WAVE IN HIGH VELOCITY AERATED FLOWS FROM HIGH HEAD DISCHARGE STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    Dong Zhi-yong

    2003-01-01

    The compressible characteristics in aerated flows at the high velocity of about 50m/s were analyzed. Based on the theory of compressible the relations between the sonic speed and shock wave in high-velocity aerated flow were theoretically deduced. And comparisons with measured data were made. The theoretical and experimental results show the sonic speed in aerated flow is merely of the order of several-dozen meters per second, and its minimum value is only 20m/s, which is far much less than that in water or air alone. So high subsonic flow, supersonic flow and transonic flow as well as compression wave, shock wave and expansion wave similarly to aerodnamics may be produced in high velocity aerated flow at the speed of the order of 50m/s. Hence the influences of these compressible characteristics on high head discharge structures can not be neglected, especially on super high dams over 200m high.

  13. Effects of Aerated Irrigation on Leaf Senescence at Late Growth Stage and Grain Yield of Rice

    Institute of Scientific and Technical Information of China (English)

    ZHU Lian-feng; Yu Sheng-miao; JIN Qian-yu

    2012-01-01

    With the japonica inbred cultivar Xiushui 09,indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials,field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice.The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate.The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK,contributing to significant increases in effective panicles,seed setting rate and grain yield.In addition,the aerated irrigation improved root function,increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering,which delayed leaf senescence process,prolonged leaf functional activity and led to enhanced grain filling.

  14. Fluctuant characteristics of two-phase flow behind a bottom aerator

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Experimental observations show that the random process of two-phase flow behind an aerator is an ergodic process and its amplitude distribution is similar to a normal distribution. The maximum pressure fluctuation is at the re-attachment point where the jet-trajectory flow over the aerator re-attaches to the bottom of the channel, and its amplitude is 2—3 times larger than when there is no aerator. There is a dominant frequency of 1.24 Hz in the model, but the coherence in the frequency domain is not obvious for other frequencies beside the dominant frequency. There is a large vortex at the re-attachment point behind the aerator but correlation among the measurement points is not obvious in the time domain.

  15. Integral Parameters for Characterizing Water, Energy, and Aeration Properties of Soilless Plant Growth Media

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda; Lopez, Jose Choc Chen; Møldrup, Per;

    2013-01-01

    systems are regaining increased worldwide attention. The optimal control of water availability and aeration is an essential prerequisite to successfully operate plant growth systems with soilless substrates such as aggregated foamed glass, perlite, rockwool, coconut coir, or mixtures thereof. While...

  16. A Novel Aeration Method for the Preparation of Algae (Dunaliella Salina) Biomass for Biofuel Production.

    OpenAIRE

    U.O. Enwereuzoh; G.N. Onyeagoro

    2014-01-01

    Preparation of algae (Dunaliela Salina) biomass in ammonia (NH4 + ) and nitrate (NO3 - ) growth media for biofuel production was investigated, with special attention on the elimination of inhibitory oxygen that adversely affects algae growth. A novel aeration method based on high and efficient transfer of carbon dioxide (CO2) required to stabilize the CO2 of the algae growth medium in a short time was adopted for the elimination of the inhibitory oxygen. The novel aeration method was found...

  17. Subsurface aeration of anaerobic groundwater : iron colloid formation and the nitrification process

    OpenAIRE

    Wolthoorn, A.

    2003-01-01

    Keywords: Iron, anaerobic groundwater, groundwater purification, heterogeneous oxidation, iron colloid formation, electron microscopy, nitrification In anaerobic groundwater iron and ammonium can be found in relatively high concentrations. These substances need to be removed when groundwater is used for the production of drinking water. Subsurface aeration can be applied to remove iron before the groundwater reaches the purification plant. The primary goal of subsurface aeration is to oxidise...

  18. Expired CO2 Levels Indicate Degree of Lung Aeration at Birth

    OpenAIRE

    Hooper, Stuart B.; Fouras, Andreas; Siew, Melissa; Wallace, Megan; Kitchen, Marcus; te Pas, Arjan B; Klingenberg, Claus; Lewis, Robert; Davis, Peter; Morley, Colin J; Schmölzer, Georg M.

    2013-01-01

    As neonatal resuscitation critically depends upon lung aeration at birth, knowledge of the progression of this process is required to guide ongoing care. We investigated whether expired CO2 (ECO2) levels indicate the degree of lung aeration immediately after birth in two animal models and in preterm infants. Lambs were delivered by caesarean section and ventilated from birth. In lambs, ECO2 levels were significantly (p

  19. Microstructure–texture relationships of aerated sugar gels: Novel measurement techniques for analysis and control

    OpenAIRE

    Herremans, Els; Bongaers, Evi; Estrade, Pascal; Gondek, Ewa; Hertog, Maarten; Jakubczyk, Ewa; Nguyen Do Trong, Nghia; Rizzolo, Anna; Saeys, Wouter; Spinelli, Lorenzo; Torricelli, Alessandro; Vanoli, Maristella; Verboven, Pieter; Nicolaï, Bart

    2013-01-01

    Proper control of the texture properties of aerated foods demands accurate measurement tools. Aerated sugar gels with identical composition but different microstructures were produced by applying different mixing times of 2, 4 and 8 minutes. Compression test and acoustic emission measurements were carried out to characterize the mechanical properties of these foams. Significant differences in deformation properties and number of acoustic events were found depending on the foaming time, indic...

  20. Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution

    Science.gov (United States)

    Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

    2000-01-01

    This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

  1. Aeration effect on Spirulina platensis growth and γ-linolenic acid production

    Directory of Open Access Journals (Sweden)

    Srinivasa Reddy Ronda

    2012-03-01

    Full Text Available The influence of aeration on algal growth and gamma-linolenic acid (GLA production in a bubble column photobioreactor was investigated. Studies were performed in a 20-L reactor at different aeration rates (0.2-2.5 vvm. Static, continuous, and periodic operation of air resulted in 41.9%, 88.4%, and 108% air saturation of dissolved oxygen, for which the corresponding values of GLA were 2.3, 6.5, and 7.5 mg·g-1 dry cell weight, respectively. An increase in the aeration rate from 0.2 to 2.5 vvm enhanced both the specific growth rate and GLA content under periodic sparging in the bicarbonate medium. With a 6-fold increase in the aeration rate, the GLA content of the alga increased by 69.64% (5.6-9.5 mg· g-1 dry cell weight. In addition, the total fatty acid (TFA content in dry biomass increased from 2.22% to 4.41%, whereas the algae maintained a constant GLA to TFA ratio within the aeration rate tested. The dependence of GLA production on the aeration rate was explained by interrelating the GLA production rate with the specific growth rate using the Luedeking and Piret mixed growth model.

  2. Aeration effect on Spirulina platensis growth and γ-Linolenic acid production.

    Science.gov (United States)

    Ronda, Srinivasa Reddy; Bokka, Chandra Sekhar; Ketineni, Chandrika; Rijal, Binod; Allu, Prasada Rao

    2012-01-01

    The influence of aeration on algal growth and gamma-linolenic acid (GLA) production in a bubble column photobioreactor was investigated. Studies were performed in a 20-L reactor at different aeration rates (0.2- 2.5 vvm). Static, continuous, and periodic operation of air resulted in 41.9%, 88.4%, and 108% air saturation of dissolved oxygen, for which the corresponding values of GLA were 2.3, 6.5, and 7.5 mg·g(-1) dry cell weight, respectively. An increase in the aeration rate from 0.2 to 2.5 vvm enhanced both the specific growth rate and GLA content under periodic sparging in the bicarbonate medium. With a 6-fold increase in the aeration rate, the GLA content of the alga increased by 69.64% (5.6-9.5 mg· g(-1) dry cell weight). In addition, the total fatty acid (TFA) content in dry biomass increased from 2.22% to 4.41%, whereas the algae maintained a constant GLA to TFA ratio within the aeration rate tested. The dependence of GLA production on the aeration rate was explained by interrelating the GLA production rate with the specific growth rate using the Luedeking and Piret mixed growth model. PMID:24031799

  3. Improving arachidonic acid fermentation by Mortierella alpina through multistage temperature and aeration rate control in bioreactor.

    Science.gov (United States)

    Gao, Min-Jie; Wang, Cheng; Zheng, Zhi-Yong; Zhu, Li; Zhan, Xiao-Bei; Lin, Chi-Chung

    2016-05-18

    Effective production of arachidonic acid (ARA) using Mortierella alpina was conducted in a 30-L airlift bioreactor. Varying the aeration rate and temperature significantly influenced cell morphology, cell growth, and ARA production, while the optimal aeration rate and temperature for cell growth and product formation were quite different. As a result, a two-stage aeration rate control strategy was constructed based on monitoring of cell morphology and ARA production under various aeration rate control levels (0.6-1.8 vvm). Using this strategy, ARA yield reached 4.7 g/L, an increase of 38.2% compared with the control (constant aeration rate control at 1.0 vvm). Dynamic temperature-control strategy was implemented based on the fermentation performance at various temperatures (13-28°C), with ARA level in total cellular lipid increased by 37.1% comparing to a constant-temperature control (25°C). On that basis, the combinatorial fermentation strategy of two-stage aeration rate control and dynamic temperature control was applied and ARA production achieved the highest level of 5.8 g/L. PMID:26038800

  4. Bioreactor tests preliminary to landfill in situ aeration: a case study.

    Science.gov (United States)

    Raga, Roberto; Cossu, Raffaello

    2013-04-01

    Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45°C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45°C in the landfill. The results obtained showed positive effects of the aeration on leachate quality and a significant reduction of waste biodegradability. Although a delay of biodegradation processes was observed in the reactor run at 45°C, biodegradation rates increased after 2 months of aeration, providing very low values of the relevant parameters (as in the other aerated reactors) by the end of the study. Mass balances were carried out for TOC and NNH4(+); the findings obtained were encouraging and provided evidence of the effectiveness of carbon and nitrogen conversion processes in the aerated landfill simulation reactors. PMID:23274082

  5. A two-fluid model for violent aerated flows

    CERN Document Server

    Dias, Frédéric; Ghidaglia, Jean-Michel

    2008-01-01

    In the study of ocean wave impact on structures, one often uses Froude scaling since the dominant force is gravity. However the presence of trapped or entrained air in the water can significantly modify wave impacts. When air is entrained in water in the form of small bubbles, the acoustic properties in the water change dramatically. While some work has been done to study small-amplitude disturbances in such mixtures, little work has been done on large disturbances in air-water mixtures. We propose a basic two-fluid model in which both fluids share the same velocities and analyze some of its properties. It is shown that this model can successfully mimic water wave impacts on coastal structures. The governing equations are discretized by a second-order finite volume method. Numerical results are presented for two examples: the dam break problem and the drop test problem. It is shown that this basic model can be used to study violent aerated flows, especially by providing fast qualitative estimates.

  6. Fate of Pathogen Indicators During Extended Aeration Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Norshuhaila Mohamed Sunar

    2015-05-01

    Full Text Available Pathogen indicators normally used in water quality indicator because large numbers of the bacteria are always present in the faeces of humans, but are not naturally found in water. Since these bacteria don’t live long in water once outside the intestine, their presence in water means there has been recent contamination through effluent discharges or other sources. Like other enteric pathogens, a common mode of transmission for E.coli is via contaminated water, food and by direct person to person contact. Infection often causes severe bloody diarrhea, abdominal cramps, and possibly fever.  In some cases, infection can lead to kidney failure and possibly death. In order to evaluate the effieciency of extended aeration wastewater treatment plant (EAWWTP, the microbial analyses such as enumeration of E.coli and total coliform were measured. Besides, this study also involved the measurements of pH, turbidity, DO (Dissolve Oxygen, BOD (Biochemical Oxygen Demand, COD (Chemical Oxygen Demand and TSS (Total Suspended Solid. This study summarized that each treatment process provides important roles to overall effieciency of EAWWTP. The secondary treatment was proved sufficient not only on reducing pathogen indicators but for all examined parameters. Significantly, this study conclude that numbers of pathogen indicators discharges in effluent meet the regulated standard guideline after treated through the EAWWTP.

  7. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    International Nuclear Information System (INIS)

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV–vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved. - Highlights: • In OH induced reactions of salicylates first products are hydroxylated derivatives. • With prolonged irradiation dihydroxy derivatives also form. • In aerated solutions the one-electron oxidant OH induces 3–4 oxidations. • Toxicity first increases and then decreases with dose mainly due to H2O2 formation. • The toxicity in tap water is smaller than in pure water

  8. Fine-pore aeration diffusers: accelerated membrane ageing studies.

    Science.gov (United States)

    Kaliman, An; Rosso, Diego; Leu, Shao-Yuan; Stenstrom, Michael K

    2008-01-01

    Polymeric membranes are widely used in aeration systems for biological treatment. These membranes may degrade over time and are sensitive to fouling and scaling. Membrane degradation is reflected in a decline in operating performance and higher headloss, resulting in increased energy costs. Mechanical property parameters, such as membrane hardness, Young's modulus, and orifice creep, were used to characterize the performance of membranes over time in operation and to predict their failure. Used diffusers from municipal wastewater treatment plants were collected and tested for efficiency and headloss, and then dissected to facilitate measurements of Young's modulus, hardness, and orifice creep. Higher degree of membrane fouling corresponded consistently with larger orifice creep. A lab-scale membrane ageing simulation was performed with polyurethane and four different ethylene-propylene-diene (EPDM) membrane diffusers by subjecting them to chemical ageing cycles and periodic testing. The results confirmed full-scale plant results and showed the superiority of orifice creep over Young's modulus and hardness in predicting diffuser deterioration. PMID:17706264

  9. Atrazine removal from aqueous solutions using submerged biological aerated filter.

    Science.gov (United States)

    Baghapour, Mohammad Ali; Nasseri, Simin; Derakhshan, Zahra

    2013-01-01

    Atrazine is widely used in the agriculture as an herbicide. Due to its high mobility, Atrazine leaks into the groundwaters, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Atrazine from aquatic environments. However, these methods are very costly, have many performance problems, produce a lot of toxic intermediates which are very harmful and dangerous, and cannot completely mineralize Atrazine. In this study, biodegradation of Atrazine by microbial consortium was evaluated in the aquatic environment. In order to assess the Atrazine removal from the aquatic environment, submerged biological aerated filter (SBAF) was fed with synthetic wastewater based on sucrose and Atrazine at different hydraulic retention times (HRTs). The maximum efficiencies for Atrazine and Soluble Chemical Oxygen Demand (SCOD) removal were 97.9% and 98.9%, respectively. The study findings showed that Stover-Kincannon model had very good fitness (R2 > 99%) in loading Atrazine in the biofilter and by increasing the initial concentration of Atrazine, the removal efficiency increased. Aerobic mixed biofilm culture was observed to be suitable for the treatment of Atrazine from aquatic environment. There was no significant inhibition effect on mixed aerobic microbial consortia. Atrazine degradation depended on the strength of wastewater and the amount of Atrazine in the influent. PMID:24499572

  10. Atrazine Removal from Aqueous Solutions using Submerged Biological Aerated Filter

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Baghapour

    2013-06-01

    Full Text Available Atrazine is widely used in the agriculture as an herbicide. Due to its high mobility, Atrazine leaks into the groundwaters, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Atrazine from aquatic environments. However, these methods are very costly, have many performance problems, produce a lot of toxic intermediates which are very harmful and dangerous, and cannot completely mineralize Atrazine. In this study, biodegradation of Atrazine by microbial consortium was evaluated in the aquatic environment. In order to assess the Atrazine removal from the aquatic environment, submerged biological aerated filter (SBAF was fed with synthetic wastewater based on sucrose and Atrazine at different hydraulic retention times (HRTs. The maximum efficiencies for Atrazine and Soluble Chemical Oxygen Demand (SCOD removal were 97.9% and 98.9%, respectively. The study findings showed that Stover-Kincannon model had very good fitness (R2 > 99% in loading Atrazine in the biofilter and by increasing the initial concentration of Atrazine, the removal efficiency increased. Aerobic mixed biofilm culture was observed to be suitable for the treatment of Atrazine from aquatic environment. There was no significant inhibition effect on mixed aerobic microbial consortia. Atrazine degradation depended on the strength of wastewater and the amount of Atrazine in the influent

  11. Studies on soil aeration with irrigation and response of crops

    International Nuclear Information System (INIS)

    The root zone of the plant must be well supplied with both water and oxygen. Water potential should be kept close to saturation but if a low water tension is maintained, particularly in clay soil, plants will suffer most of the time from a suboptimal level of oxygen supply in the root zone. The diffusion rate of gases in the air is about 10,000 times greater than in water. Thus, it is obvious that the rate of gas diffusion decreases as the water content of the soil increases. These two requirements are apparently contradictory and the assessment of optimum level of soil aeration in the root environment is essential for better crop establishment and growth. Influence of irrigation treatments (three depths of irrigation of 2, 4 and 6 cm and four IW/CPE ratios of 0.45, 0.60, 0.75 and 0.90) on the soil oxygen diffusion rate (ODR) during various growing phases of peanut crop (Arachis hypogaea L.) were studied on a lateritic sandy loam soil (ultisols) for two consecutive seasons. The rate of ODR decreases as water content of the soil increases after irrigation and then increases gradually with the lapse of time. However, it starts decreasing with decrease in soil moisture after 96 hours of irrigation. (author)

  12. Glucose Metabolism in Lactococcus lactis MG1363 under Different Aeration Conditions: Requirement of Acetate To Sustain Growth under Microaerobic Conditions

    OpenAIRE

    Nordkvist, Mikkel; Jensen, Niels Bang Siemsen; Villadsen, John

    2003-01-01

    Lactococcus lactis subsp. lactis MG1363 was grown in batch cultures on a defined medium with glucose as the energy source under different aeration conditions, namely, anaerobic conditions, aerobic conditions, and microaerobic conditions with a dissolved oxygen tension of 5% (when saturation with air was used as the reference). The maximum specific growth rate was high (0.78 to 0.91 h−1) under all aeration conditions but decreased with increasing aeration, and more than 90% of the glucose was ...

  13. Investigation of flow dynamics in aeration chamber in biological sewage treatment plant for selection of its optimal working parameters

    International Nuclear Information System (INIS)

    The subject of study was an activated sludge chamber in treatment station of petrochemical effluent. The chamber has been equipped with two surface aerators. A series of tracer evaluations of residence time distribution curves was performed for various immersion of aerators. The measurement of power consumption of aerators and COD reduction occurring in the chamber were recorded. The results obtained were applied to select the optimal working condition of the chamber. (author). 8 refs, 4 figs, 1 tabs

  14. CAVITATION CHARACTERISTICS OF HIGH VELOCITY FLOW WITH AND WITHOUT AERATION ON THE ORDER OF 50 m/s

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Experimental study of cavitation characteristics with and without aeration was conducted at the flow velocity 50m/s in the non-circulating type water tunnel in the Hydraulics Laboratory at Zhejiang University of Technology. Variations of pressure and cavitation number with air concentration, pressure waveforms as well as cavitation erosion level of concrete specimen with and without aeration were obtained. The effects of cavitation control by aeration were analyzed.

  15. Reducing aeration energy consumption in a large-scale membrane bioreactor: Process simulation and engineering application.

    Science.gov (United States)

    Sun, Jianyu; Liang, Peng; Yan, Xiaoxu; Zuo, Kuichang; Xiao, Kang; Xia, Junlin; Qiu, Yong; Wu, Qing; Wu, Shijia; Huang, Xia; Qi, Meng; Wen, Xianghua

    2016-04-15

    Reducing the energy consumption of membrane bioreactors (MBRs) is highly important for their wider application in wastewater treatment engineering. Of particular significance is reducing aeration in aerobic tanks to reduce the overall energy consumption. This study proposed an in situ ammonia-N-based feedback control strategy for aeration in aerobic tanks; this was tested via model simulation and through a large-scale (50,000 m(3)/d) engineering application. A full-scale MBR model was developed based on the activated sludge model (ASM) and was calibrated to the actual MBR. The aeration control strategy took the form of a two-step cascaded proportion-integration (PI) feedback algorithm. Algorithmic parameters were optimized via model simulation. The strategy achieved real-time adjustment of aeration amounts based on feedback from effluent quality (i.e., ammonia-N). The effectiveness of the strategy was evaluated through both the model platform and the full-scale engineering application. In the former, the aeration flow rate was reduced by 15-20%. In the engineering application, the aeration flow rate was reduced by 20%, and overall specific energy consumption correspondingly reduced by 4% to 0.45 kWh/m(3)-effluent, using the present practice of regulating the angle of guide vanes of fixed-frequency blowers. Potential energy savings are expected to be higher for MBRs with variable-frequency blowers. This study indicated that the ammonia-N-based aeration control strategy holds promise for application in full-scale MBRs. PMID:26905799

  16. Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water.

    Science.gov (United States)

    Dong, Huiyu; Qiang, Zhimin; Li, Tinggang; Jin, Hui; Chen, Weidong

    2012-01-01

    Three lab-scale vertical-flow constructed wetlands (VFCWs), including the non-aerated (NA), intermittently aerated (IA) and continuously aerated (CA) ones, were operated at different hydraulic loading rates (HLRs) to evaluate the effect of artificial aeration on the treatment efficiency of heavily polluted river water. Results indicated that artificial aeration increased the dissolved oxygen (DO) concentrations in IA and CA, which significantly favored the removal of organic matter and NH(4+)-N. The DO grads caused by intermittent aeration formed aerobic and anoxic regions in IA and thus promoted the removal of total nitrogen (TN). Although the removal efficiencies of COD(Cr), NH(4+)-N and TN in the three VFCWs all decreased with an increase in HLR, artificial aeration enhanced the reactor resistance to the fluctuation of pollutant loadings. The maximal removal efficiencies of COD(Cr), NH(4+)-N and total phosphorus (TP) (i.e., 81%, 87% and 37%, respectively) were observed in CA at 19 cm/day HLR, while the maximal TN removal (i.e., 57%) was achieved in IA. Although the improvement of artificial aeration on TP removal was limited, this study has demonstrated the feasibility of applying artificial aeration to VFCWs treating polluted river water, particularly at a high HLR. PMID:22894092

  17. Optimizing aeration rates for minimizing membrane fouling and its effect on sludge characteristics in a moving bed membrane bioreactor

    International Nuclear Information System (INIS)

    Research highlights: → There is an optimum aeration rate in the MBMBR process compartments. → Optimum aeration rate maximizes nutrients removal. → Optimum aeration rate minimizes membrane fouling. → Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h-1 and a specific aeration demand per membrane area (SADm) of 1.2 and 0.4mair3 m-2 h-1, respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SADm significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SADm were 151 L h-1 and 0.8-1.2mair3mmembrane-2 h-1, respectively.

  18. Nitrogen removal via short-cut simultaneous nitrification and denitrification in an intermittently aerated moving bed membrane bioreactor

    International Nuclear Information System (INIS)

    Highlights: → An intermittently aerated MBMBR was investigated to achieve SND via nitrite. → The intermittent-aeration strategy was an effective approach to achieve nitrition. → The activities of NOBs were inhibited under the intermittently aerated mode. → The intermittently aerated mode had no effect on the activities of AOBs. - Abstract: An intermittently aerated moving bed membrane bioreactor (MBMBR) was developed and crucial parameters affecting nitrogen removal from wastewater by simultaneous nitrification and denitrification via nitrite were investigated, without strict control of solids retention time. Changes in the microbiological community and distribution in the reactor were monitored simultaneously. The intermittent-aeration strategy proved effective in achieving nitrition and the chemical oxygen demand (COD) to total nitrogen (TN) ratio was an important factor affecting TN removal. In the MBMBR, the nitrite accumulation rate reached 79.4% and TN removal efficiency averaged at 87.8% with aeration 2 min/mix 4 min and an influent COD/TN ratio of 5. Batch tests indicated that under the intermittently aerated mode, nitrite-oxidizing bacteria (NOB) were not completely washed out from the reactor but NOB activity was inhibited. The intermittently aerated mode had no effect on the activities of ammonia-oxidizing bacteria. Fluorescence in situ hybridizations (FISH) results also suggested that NOBs remained within the system.

  19. Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water

    Institute of Scientific and Technical Information of China (English)

    Huiyu Dong; Zhimin Qiang; Tinggang Li; Hui Jin; Weidong Chen

    2012-01-01

    Three lab-scale vertical-flow constructed wetlands (VFCWs),including the non-aerated (NA),intermittently aerated (IA) and continuously aerated (CA) ones,were operated at different hydraulic loading rates (HLRs) to evaluate the effect of artificial aeration on the treatment efficiency of heavily polluted river water.Results indicated that artificial aeration increased the dissolved oxygen (DO) concentrations in IA and CA,which significantly favored the removal of organic matter and NH4+-N.The DO grads caused by intermittent aeration formed aerobic and anoxic regions in IA and thus promoted the removal of total nitrogen (TN).Although the removal efficiencies of CODcr,NH4+-N and TN in the three VFCWs all decreased with an increase in HLR,artificial aeration enhanced the reactor resistance to the fluctuation of pollutant loadings.The maximal removal efficiencies of CODcr,NH4+-N and total phosphorus (TP) (i.e.,81%,87% and 37%,respectively) were observed in CA at 19 cm/day HLR,while the maximal TN removal (i.e.,57%) was achieved in IA.Although the improvement of artificial aeration on TP removal was limited,this study has demonstrated the feasibility of applying artificial aeration to VFCWs treating polluted eiver water,particularly at a high HLR.

  20. Glucose metabolism in Lactococcus lactis MG1363 under different aeration conditions: Requirement of acetate to sustain growth under microaerobic conditions

    DEFF Research Database (Denmark)

    Nordkvist, Mikkel; Jensen, N.B.S.; Villadsen, John

    2003-01-01

    Lactococcus lactis subsp. lactis MG1363 was grown in batch cultures on a defined medium with glucose as the energy source under different aeration conditions, namely, anaerobic conditions, aerobic conditions, and microaerobic conditions with a dissolved oxygen tension of 5% (when saturation with...... air was used as the reference). The maximum specific growth rate was high (0.78 to 0.91 h(-1)) under all aeration conditions but decreased with increasing aeration, and more than 90% of the glucose was converted to lactate. However, a shift in by-product formation was observed. Increasing aeration...

  1. Impact of post-infiltration soil aeration at different growth stages of sub-surface trickle-irrigated tomato plants

    Science.gov (United States)

    Li, Yuan; Jia, Zong-xia; Niu, Wen-Quan; Wang, Jing-wei

    2016-07-01

    Sensitivity to low rhizosphere soil aeration may change over time and therefore plant response may also depend on different growth stages of a crop. This study quantified effects of soil aeration during 5 different periods, on growth and yield of trickle-irrigated potted single tomato plants. Irrigation levels were 0.6 to 0.7 (low level) or 0.7 to 0.8 (high level) of total water holding capacity of the pots. Soil was aerated by injecting 2.5 l of air into each pot through the drip tubing immediately after irrigation. Fresh fruit yield, above ground plant dry weight, plant height, and leaf area index response to these treatments were measured. For all these 4 response variables, means of post-infiltration aeration between 58 to 85 days after sowing were 13.4, 43.5, 13.7, and 37.7% higher than those for the non-aerated pots, respectively. The results indicated that: post-infiltration soil aeration can positively impact the yield and growth of sub-surface trickle-irrigated potted tomato plants; positive effects on plant growth can be obtained with aeration during the whole growth period or with aeration for partial periods; positive growth effects of partial periods of aeration appears to persist and result in yield benefit.

  2. Development of a stepwise aeration control strategy for efficient docosahexaenoic acid production by Schizochytrium sp.

    Science.gov (United States)

    Ren, Lu-Jing; Ji, Xiao-Jun; Huang, He; Qu, Liang; Feng, Yun; Tong, Qian-Qian; Ouyang, Ping-Kai

    2010-08-01

    The effect of aeration on the performance of docosahexaenoic acid (DHA) production by Schizochytrium sp. was investigated in a 1,500-L bioreactor using fed-batch fermentation. Six parameters, including specific growth rate, specific glucose consumption rate, specific lipid accumulation rate, cell yield coefficient, lipid yield coefficient, and DHA yield coefficient, were used to understand the relationship between aeration and the fermentation characteristics. Based on the information obtained from the parameters, a stepwise aeration control strategy was proposed. The aeration rate was controlled at 0.4 volume of air per volume of liquid per minute (vvm) for the first 24 h, then shifted to 0.6 vvm until 96 h, and then switched back to 0.4 vvm until the end of the fermentation. High cell density (71 g/L), high lipid content (35.75 g/L), and high DHA percentage (48.95%) were achieved by using this strategy, and DHA productivity reached 119 mg/L h, which was 11.21% over the best results obtained by constant aeration rate. PMID:20445973

  3. Aeration strategy: a need for very high ethanol performance in Saccharomyces cerevisiae fed-batch process.

    Science.gov (United States)

    Alfenore, S; Cameleyre, X; Benbadis, L; Bideaux, C; Uribelarrea, J-L; Goma, G; Molina-Jouve, C; Guillouet, S E

    2004-02-01

    In order to identify an optimal aeration strategy for intensifying bio-fuel ethanol production in fermentation processes where growth and production have to be managed simultaneously, we quantified the effect of aeration conditions--oxygen limited vs non limited culture (micro-aerobic vs aerobic culture)--on the dynamic behaviour of Saccharomyces cerevisiae cultivated in very high ethanol performance fed-batch cultures. Fermentation parameters and kinetics were established within a range of ethanol concentrations (up to 147 g l(-1)), which very few studies have addressed. Higher ethanol titres (147 vs 131 g l(-1) in 45 h) and average productivity (3.3 vs 2.6 g l(-1) h(-1)) were obtained in cultures without oxygen limitation. Compared to micro-aerobic culture, full aeration led to a 23% increase in the viable cell mass as a result of the concomitant increase in growth rate and yield, with lower ethanol inhibition. The second beneficial effect of aeration was better management of by-product production, with production of glycerol, the main by-product, being strongly reduced from 12 to 4 g l(-1). We demonstrate that aeration strategy is as much a determining factor as vitamin feeding (Alfenore et al. 2002) in very high ethanol performance (147 g l(-1) in 45 h) in order to achieve a highly competitive dynamic process. PMID:12879304

  4. Nitrogen transformations and retention in planted and artificially aerated constructed wetlands.

    Science.gov (United States)

    Maltais-Landry, Gabriel; Maranger, Roxane; Brisson, Jacques; Chazarenc, Florent

    2009-02-01

    Nitrogen (N) processing in constructed wetlands (CWs) is often variable, and the contribution to N loss and retention by various pathways (nitrification/denitrification, plant uptake and sediment storage) remains unclear. We studied the seasonal variation of the effects of artificial aeration and three different macrophyte species (Phragmites australis, Typha angustifolia and Phalaris arundinacea) on N processing (removal rates, transformations and export) using experimental CW mesocosms. Removal of total nitrogen (TN) was higher in summer and in planted and aerated units, with the highest mean removal in units planted with T. angustifolia. Export of ammonium (NH(4)(+)), a proxy for nitrification limitation, was higher in winter, and in unplanted and non-aerated units. Planted and aerated units had the highest export of oxidized nitrogen (NO(y)), a proxy for reduced denitrification. Redox potential, evapotranspiration (ETP) rates and hydraulic retention times (HRT) were all predictors of TN, NH(4)(+) and NO(y) export, and significantly affected by plants. Denitrification was the main N sink in most treatments accounting for 47-62% of TN removal, while sediment storage was dominant in unplanted non-aerated units and units planted with P. arundinacea. Plant uptake accounted for less than 20% of the removal. Uncertainties about the long-term fate of the N stored in sediments suggest that the fraction attributed to denitrification losses could be underestimated in this study. PMID:19036399

  5. [Effect of Intermittent Aeration on Nitrogen Removal Efficiency in Vertical Subsurface Flow Constructed Wetland].

    Science.gov (United States)

    Wang, Jian; Li, Huai-zheng; Zhen, Bao-chong; Liu, Zhen-dong

    2016-03-15

    One-stage vertical subsurface flow constructed wetlands (CWs) were used to treat effluent from grit chamber in municipal wastewater treatment plant. The CW was divided into aerobic zone and anoxic zone by means of raising the effluent level and installing a perforated pipe. Two parameters (the ratio of aeration time and nonaeration time, aeration cycle) were optimized in the experiment to enhance nitrogen removal efficiency. The results suggested that the removal rates of COD and NH₄⁺-N increased while TN showed a trend of first increasing and then decreasing with the increasing ratio. When the ratio was 3:1, the C/N value in the anoxic zone was 4. 8. And the TN effluent concentration was 15.8 mg · L⁻¹ with the highest removal rate (62.1%), which was increased by 12.7% compared with continuous aeration. As the extension of the aeration cycle, the DO effluent concentration as well as the removal rates of COD and NH: -N declined gradually. The TN removal rate reached the maximum (65.5%) when the aeration cycle was 6h. However, the TN removal rate dropped rapidly when the cycle exceeded the hydraulic retention time in the anoxic zone. PMID:27337890

  6. Aerated Shewanella oneidensis in continuously fed bioelectrochemical systems for power and hydrogen production.

    Science.gov (United States)

    Rosenbaum, Miriam; Cotta, Michael A; Angenent, Largus T

    2010-04-01

    We studied the effects of aeration of Shewanella oneidensis on potentiostatic current production, hydrogen production in a microbial electrolysis cell, and electric power generation in a microbial fuel cell (MFC). The potentiostatic performance of aerated S. oneidensis was considerably enhanced to a maximum current density of 0.45 A/m(2) or 80.3 A/m(3) (mean: 0.34 A/m(2), 57.2 A/m(3)) compared to anaerobically grown cultures. Biocatalyzed hydrogen production rates with aerated S. oneidensis were studied within the applied potential range of 0.3-0.9 V and were highest at 0.9 V with 0.3 m(3) H(2)/m(3) day, which has been reported for mixed cultures, but is approximately 10 times higher than reported for an anaerobic culture of S. oneidensis. Aerated MFC experiments produced a maximum power density of 3.56 W/m(3) at a 200-Omega external resistor. The main reasons for enhanced electrochemical performance are higher levels of active biomass and more efficient substrate utilization under aerobic conditions. Coulombic efficiencies, however, were greatly reduced due to losses of reducing equivalents to aerobic respiration in the anode chamber. The next challenge will be to optimize the aeration rate of the bacterial culture to balance between maximization of bacterial activation and minimization of aerobic respiration in the culture. PMID:19998276

  7. Optimisation of pressure aeration systems in waste water treatment; Optimierung von Druckbelueftungssystemen in der Abwasserbehandlung

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.

    2002-07-01

    This paper investigates, evaluates and places in context a diverse range of factors impacting on the performance of aerator elements used in the pressure aeration of wastewater treatment. To perform the investigation, a large-scale test basin and column were installed to allow oxygen transfer tests to be conducted under identical and hence reproducible boundary conditions. In addition to standard model aerators, numerous prototypes of disc, pipe and hose aerators were produced which differed in individual design characteristics or other properties. The various designs were installed in the experimental set-up and their performance measured by means of oxygen transfer tests using the desorption method. Based on these findings as well as on the detailed theoretical principles and the empirical investigations, recommendations were drawn up for the optimisation of pressurised aerator systems which will allow a significant reduction in the required volumes of air and hence in the cost of electricity for the compressors and blowers without a reduction in performance. (orig.)

  8. Nitrogen removal in the bioreactor landfill system with intermittent aeration at the top of landfilled waste

    International Nuclear Information System (INIS)

    High ammonia concentration of recycled landfill leachate makes it very difficult to treat. In this work, a vertical aerobic/anoxic/anaerobic lab-scale bioreactor landfill system, which was constructed by intermittent aeration at the top of landfilled waste, as a bioreactor for in situ nitrogen removal was investigated during waste stabilization. Intermittent aeration at the top of landfilled waste might stimulate the growth of nitrifying bacteria and denitrifying bacteria in the top and middle layers of waste. The nitrifying bacteria population for the landfill bioreactor with intermittent aeration system reached between106 and 108 cells/dry g waste, although it decreased 2 orders of magnitude on day 30, due to the inhibitory effect of the acid environment and high organic matter in the landfilled waste. The denitrifying bacteria population increased by between 4 and 13 orders of magnitude compared with conventional anaerobic landfilled waste layers. Leachate NO3--N concentration was very low in both two experimental landfill reactors. After 105 days operation, leachate NH4+-N and TN concentrations for the landfill reactor with intermittent aeration system dropped to 186 and 289 mg/l, respectively, while they were still kept above 1000 mg/l for the landfill reactor without intermittent aerobic system. In addition, there is an increase in the rate of waste stabilization as well as an increase of 12% in the total waste settlement for the landfill reactor with intermittent aeration system

  9. Influence of Gabcikovo hydro power structures on the dynamics of water in the aeration zone

    International Nuclear Information System (INIS)

    For the quantification of the influence of ground water level changes and fluctuation on water dynamics in the aeration zone the three following characteristics have been choseN: 1) the course of cumulative water content in the aeration zone, monitored during the period 1990 to 1994; 2) quarterly averages of water content in the aeration zone in the zone in the period 1990 to 1994; 3) the quantification of the participation of individual soil horizons on cumulative water content in the aeration zone in given time intervals for selected typical monitored locations. The negative changes of the ground water after setting the Gabcikovo structures into operation as predicted by some authors, were not confirmed in the monitoring period (two years prior to setting the Gabcikovo structures into operation, one year during the transitional period, and two years after damming) and were not negatively reflected in the changes of water content in the soil zone of aeration. (authors). 1 tabs., figs., 1 map, 21 refs

  10. EXPERIMENTAL AND NUMERICAL SIMULATION OF THREE-PHASE FLOW IN AN AERATION TANK

    Institute of Scientific and Technical Information of China (English)

    Cheng Wen; Zhou Xiao-de; Song Ce; Min Tao; Murai Yuichi; Yamamoto Fujio

    2003-01-01

    Aeration plays an important role in the treatment of activated sludge due to the interactions among bubbles, sewage and activated sludge in an aeration tank. The aeration performance is directly concerned with the efficiency of sewage disposal. So the three-dimensional two-fluid model was established with emphasis on the phase interaction terms in this paper. This model, as an extension of the two-phase flow model, involved the motion laws of three-phases, and was compared with experimental studies. The finite volume method was used in the numerical simulation of gas-liquid two-phase flow and gas-liquid-solid three-phase flow. In order to discuss the influence of gas-phase, liquid-phase and solid-phase motions in an aeration tank on the sewage disposal, three kinds of boundary and initial conditions were adopted. The simulated results of the flow structure show qualitatively good agreement with the experimental data. And the theoretical basis for designing the best aeration tank was discussed according to the simulated results.

  11. Influence of aeration and initial water thickness on axial velocity attenuation of jet flows

    Institute of Scientific and Technical Information of China (English)

    Wang-ru WEI; Jun DENG; Bin LIU

    2013-01-01

    With the development of ski-jump energy dissipation for high and large discharge among the hydraulic projects,the effects of characteristics of water flow on energy dissipation are increasingly important.In the present study,the effects of aeration and the initial water thickness on axial velocity attenuation of jet flow were analyzed,using variance analysis and numerical calculated methods.From the analysis of test data,both of the air concentration and initial water thickness are sensitive factors for the axial velocity attenuation of jet flow along the axial way,and there is no significant interaction effect between the aeration and initial water thickness.Aeration has a more significant effect on the axial velocity attenuation of jet flow.Decreasing the initial water thickness of jet flow can reduce the length of jet core,and make the initial position of axial velocity attenuation closer to the nozzle exit.The numerical calculation results show that aeration can contribute to the enhancement of entrainment ability of jet flow,which may improve the interaction between jet flow and surroundings.For ski-jump energy dissipation among the hydraulic projects,combining aeration with decreasing initial water thickness of jet flow is an effective way to enhance the rate of axial velocity attenuation.

  12. [Effect of intermittent artificial aeration on nitrogen and phosphorus removal in subsurface vertical-flow constructed wetlands].

    Science.gov (United States)

    Tang, Xian-qiang; Li, Jin-zhong; Li, Xue-Ju; Liu, Xue-gong; Huang, Sui-liang

    2008-04-01

    Shale and T. latifolia were used as subsurface vertical-flow constructed wetland substrate and vegetation for eutrophic Jin River water treatment, and investigate the effect of intermittent aeration on nitrogen and phosphorus removal. In this study, hydraulic loading rate was equal to 800 mm/d, and ratio of air and water was 5:1. During the entire running period, maximal monthly mean ammonia-nitrogen (NH4+ -N), total nitrogen (TN), soluble reactive phosphorus (SRP) and total phosphorus (TP) removal rates were observed in August 2006. In contrast to the non-aerated wetland, aeration enhanced ammonia-nitrogen, total nitrogen, soluble reactive phosphorus and total phosphorus removal: 10.1%, 4.7%, 10.2% and 8.8% for aeration in the middle, and 25.1%, 10.0%, 7.7% and 7.4% for aeration at the bottom of the substrate, respectively. However, aeration failed to improve the nitrate-nitrogen removal. During the whole experimental period, monthly mean NO3(-) -N removal rates were much lower for aerated constructed wetlands (regarding aeration in the middle and at the bottom) than those for non-aerated system. After finishing the experiment, aboveground plant biomass (stems and leaves) of T. latifolia was harvested, and its weight and nutrient content (total nitrogen and total phosphorus) were measured. Analysis of aboveground plant biomass indicated that intermittent aeration restrained the increase in biomass but stimulated assimilation of nitrogen and phosphorus into stems and leaves. Additional total nitrogen removal of 11.6 g x m(-2) and 12.6 g x m(-2) by aboveground T. latifolia biomass for intermittent artificial aeration in the middle and at the bottom of the wetland substrate, respectively, was observed. PMID:18637335

  13. Radon removal equipment based on aeration: A literature study of tests performed in Sweden between 1981 and 1996

    Energy Technology Data Exchange (ETDEWEB)

    Mjoenes, L

    2000-02-01

    In Sweden some principles to reduce the radon concentration in drinking water were tested in the beginning of the 1980s. Spray aeration under atmospheric pressure, diffused bubble aeration, aeration in the pressure tank and different combinations of these principles were studied. Aeration in the drill hole and adsorption on granulated activated char-coal were also tested. The best results, about 70 % reduction, were obtained with aeration in the pressure tank with a spray system combined with diffused air bubbling. The Oerebro project in the beginning of the 1990s included on site testing of five different aeration solutions: Aeration in the drill hole, aeration in the storage tank, ejector aeration, shallow tray aeration and packed column aeration. The radon removal efficiency varied between 20 % and 99 %. In 1994 a study intended to test the radon removal capacity of different water treatment equipment was performed. Six units of radon separators were included but most of the tested equipment was installed for other water treatment purposes. The performed measurements showed that the only types of equipment that reduce the radon concentration efficiently are radon separators and reverse osmosis filters. The radon removal capacity of the radon separators varied between 23 % and 97 %. In 1996 the nine most common radon separators on the Swedish market were tested. The results showed that the tested radon removal equipment worked well, although the technical quality and chosen technical solutions were not always the best. The radon removal capacity of the units participating in this test was in most cases between 96 and 99 %. In some cases the capacity exceeded 99 %. In order to reach this radon removal capacity the water must be recirculated in a storage tank under atmospheric pressure.

  14. Radon removal equipment based on aeration: A literature study of tests performed in Sweden between 1981 and 1996

    International Nuclear Information System (INIS)

    In Sweden some principles to reduce the radon concentration in drinking water were tested in the beginning of the 1980s. Spray aeration under atmospheric pressure, diffused bubble aeration, aeration in the pressure tank and different combinations of these principles were studied. Aeration in the drill hole and adsorption on granulated activated char-coal were also tested. The best results, about 70 % reduction, were obtained with aeration in the pressure tank with a spray system combined with diffused air bubbling. The Oerebro project in the beginning of the 1990s included on site testing of five different aeration solutions: Aeration in the drill hole, aeration in the storage tank, ejector aeration, shallow tray aeration and packed column aeration. The radon removal efficiency varied between 20 % and 99 %. In 1994 a study intended to test the radon removal capacity of different water treatment equipment was performed. Six units of radon separators were included but most of the tested equipment was installed for other water treatment purposes. The performed measurements showed that the only types of equipment that reduce the radon concentration efficiently are radon separators and reverse osmosis filters. The radon removal capacity of the radon separators varied between 23 % and 97 %. In 1996 the nine most common radon separators on the Swedish market were tested. The results showed that the tested radon removal equipment worked well, although the technical quality and chosen technical solutions were not always the best. The radon removal capacity of the units participating in this test was in most cases between 96 and 99 %. In some cases the capacity exceeded 99 %. In order to reach this radon removal capacity the water must be recirculated in a storage tank under atmospheric pressure

  15. ON NECESSITY OF PLACING AN AERATOR IN THE BOTTOM DISCHARGE TUNNEL AT THE LONGTAN HYDROPOWER STATION

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; WU Wei-wei; RUAN Shi-ping

    2006-01-01

    The air entrainment for avoiding cavitation damage has been widely used in long free flow tunnels. It is crucial to determine whether an aerator is needed for shorter tunnels. In this article, the bottom discharge tunnel at the Longtan Hydropower Station was involved, for which the free flow tunnel section was only 50.00 m long. The cavitation in the tunnel with and without the aerator was investigated using the physical models of the scale 1/30, through the measurements of cavitation noise. The experimental results show that it is necessary to place the aerator at the inlet of the free flow section for higher reservoir level to protect this tunnel from cavitation damage.

  16. A Novel Aeration Method for the Preparation of Algae (Dunaliella Salina Biomass for Biofuel Production.

    Directory of Open Access Journals (Sweden)

    U.O. Enwereuzoh

    2014-09-01

    Full Text Available Preparation of algae (Dunaliela Salina biomass in ammonia (NH4 + and nitrate (NO3 - growth media for biofuel production was investigated, with special attention on the elimination of inhibitory oxygen that adversely affects algae growth. A novel aeration method based on high and efficient transfer of carbon dioxide (CO2 required to stabilize the CO2 of the algae growth medium in a short time was adopted for the elimination of the inhibitory oxygen. The novel aeration method was found to increase the algae growth rate in the growth media investigated as suggested by increases in pH and decreases in dissolved oxygen concentration. However, algae grown in ammonia medium showed 17% higher growth rate than algae grown in nitrate medium. The high mass transfer of CO2 and high energy efficiency make the novel aeration method of algae growth in ammonia medium better suited for high yield of algae biomass for biofuel production.

  17. A Novel Surface Aeration Configuration for Improving Gas—Liquid Mass Transfer

    Institute of Scientific and Technical Information of China (English)

    YUGengzhi; MAZaisha; 等

    2002-01-01

    A novel surface aeration configuration featured with a self-rotating and floating baffle (SRFB) and a Rushton disk turbine (DT) with a perforated disk has been developed. The SRFB, consisted of 12 fan blades twisted by an angle of 30° to the horizontal plane, is incorporated onto the impeller shaft to improve gas entrainment, bubble breakup, mixing in a φ154mm agitated vessel. This new configuration is compared to the conventional DT surface aeration experimentally. The results suggest that the critical impeller speed for onset of gas entrainments is lower for the new configuration and it demands greater power consumption. Moreover, the SRFB system produces 30%-68% higher volumetric mass transfer coefficient per unit power input than that obtained in the conventional DT surface aerator under the same operation conditions.

  18. Tritium capture by clay mineral structure during its propagation in aeration zone

    International Nuclear Information System (INIS)

    The underlay compositions in aeration zone have been contaminated near radioactive waste repositories as a result of radiation accident in which tritium leakage from repositories had been occurred. The tritium distribution in aeration zone and its moving into the first aquifer are investigated. Measurements of tritium activity in aeration zone have reviled, that tritium is captured by OH - groups of clay minerals. The measuring and modeling process of tritium capture by OH - groups of clay minerals let to estimate an amount of tritium, captured by OH - groups and typical times of capture and retention. It was shown that the tritium capture by OH - groups of clay minerals during its propagation into environment in some times improve the protective properties of the barrier consisting of clay minerals

  19. Study on Migration and Transformation Rule of Organic Pollutants (COD) in Aerated Zone

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Collecting waste water with a certain concentration of organic pollutants COD (chemical oxygen demand), static adsorption, static biodegradation and dynamic soil column experiments were made in laboratory, we researched migration and transformation of COD in aerated zone, and put forward a mathematical model showing the process. The results show that adsorption of organism in aerated zone is linear, which is represented by Henry's law s=Kdc+sd, adsorption coefficient Kd =0. 069 3;biodegradation diagram accord basically with first-order kinetics equation c=c0e-K1t , biodegradation coefficient K1 = 0. 049 9 d-1; dispersion coefficient D= 0. 002 42 m2/d in experiments. The migration and transformation of organic pollutants (COD) in aerated zone jointly result from many factors such as dispersion, adsorption and biodegradation etc..

  20. RBF methods for solving laterally averaged Saint Venant equations: application to eutrophication prevention through aeration

    Science.gov (United States)

    Halassi, A.; Ouazar, D.; Taik, A.

    2015-10-01

    A vertical 2Dxz laterally averaged hydrodynamic model is presented in this paper to study the aeration process in lakes. The system exhibits highly nonlinear behaviour due to the phenomena involved such as stratification, air concentration, and convective terms. The suggested model is used to simulate mechanical aeration to overcome and prevent the eutrophication in lakes. The multiquadric radial basis functions are used to solve numerically the governing partial differential equations. Because of the difficulty and the complexity when choosing a suitable shape parameter in radial basis functions, an alternative way is introduced in this work to overcome these difficulties. A validation study is carried out using several test examples, including Poisson, Navier-Stokes and transport equations. Finally, the proposed model is first applied to simulate a squared domain aeration problem and then a real test case has been considered. The obtained results are in good agreement with the results reported in the literature.

  1. Thermal Response Of An Aerated Concrete Wall With Micro-Encapsulated Phase Change Material

    Directory of Open Access Journals (Sweden)

    Halúzová Dušana

    2015-06-01

    Full Text Available For many years Phase Change Materials (PCM have attracted attention due to their ability to store large amounts of thermal energy. This property makes them a candidate for the use of passive heat storage. In many applications, they are used to avoid the overheating of the temperature of an indoor environment. This paper describes the behavior of phase change materials that are inbuilt in aerated concrete blocks. Two building samples of an aerated concrete wall were measured in laboratory equipment called “twin-boxes”. The first box consists of a traditional aerated concrete wall; the second one has additional PCM micro-encapsulated in the wall. The heat flux through the wall was measured and compared to simulation results modeled in the ESP-r program. This experimental measurement provides a foundation for a model that can be used to analyze further building constructions.

  2. Evaluation on aeration performance of movable solar aerator%移动式太阳能增氧机的增氧性能评价

    Institute of Scientific and Technical Information of China (English)

    吴宗凡; 程果锋; 王贤瑞; 刘兴国; 张拥军; 邹海生; 唐荣

    2014-01-01

    为改善池塘养殖环境,设计了一种移动式太阳能增氧机,由光伏供电装置和水面行走装置搭载涌浪机而成,能在水面沿钢丝绳移动并利用涌浪机的波浪增氧和水层交换作用,大范围扰动水体并为池塘增氧。该研究的目的是通过机械增氧效率检测、提水能力测定和池塘增氧能力测定3个试验,评估太阳能增氧机的机械增氧性能、水层交换性能和实际应用效果,以期全面了解移动增氧机增氧能力。结果表明,该移动式太阳能增氧机最大机械增氧能力为1.24 kg/h,动力效率2.59 kg/(kW·h);最大提水能力1254.4 m3/h,提水动力效率2613.3 m3/(kW·h);并在晴好天气白天(09:00—19:00),在对照组底层溶氧为3.1~3.8 mg/L时,大幅度提升池塘底层溶氧水平,最高时达7.8 mg/L,维持池塘上下溶氧均匀度72%~84%,极大改善了底层溶氧环境。数据表明移动式太阳能增氧机具有良好的机械增氧和水层交换性能,因而能有效改善池塘底层溶氧环境,提高上下水体溶氧均匀度。该研究结果可为太阳能增氧机的进一步推广应用提供数据支撑。%In pond aquaculture, it is usually necessary in sunny noon that running aerator stirs pond water, so that the supersaturated dissolved oxygen (DO) from phytoplankton’s photosynthesis in upper water can be transferred into the relatively anoxic bottom, reducing the“oxygen debt”of bottom water and preventing fish hypoxia at the next early morning. However, this approach consumes a lot of electric energy and has low efficiency. To improve the ecological state of aquaculture ponds and save electric energy, a movable solar aerator was designed and developed. This machine is solar-powered and can move upon the water, and mainly consists of a photovoltaic power system, a water walking device, and a wave aerator. The photovoltaic power system provides power for the entire machine

  3. Colloid formation in groundwater by subsurface aeration: characterisation of the geo-colloids and their counterparts

    International Nuclear Information System (INIS)

    Subsurface aeration is used to oxidise Fe in situ in groundwater to make the water potable. In a groundwater system with pH > 7, subsurface aeration results in a non-mobile Fe precipitate and mobile Fe colloids. Since originally the goal of subsurface aeration is to remove Fe in situ, the formation of non-mobile Fe precipitate is the desired result. In addition to this intended effect, subsurface aeration may also strongly enhance the microbiological removal of NH4 in the purification station. A hypothesis is that mobile Fe colloids may be the link between subsurface aeration and the positive effect on the microbiological removal of NH4. The objective of this study is to characterise the mobile Fe colloids and to derive a synthetic substitute for the naturally formed Fe colloids in order to be able to apply the Fe colloids as a management tool to enhance the removal of NH4 in the process of producing drinking water from groundwater. At a purification station in The Netherlands natural Fe colloids from an aerated well were sampled. Furthermore, eight synthetic Fe colloids were prepared by oxidising synthetic solutions differing in elemental composition. The colloids were analysed using chemical analysis and electron microscopy (SEM and SEM-EDAX). The Fe colloids sampled in the field contained Fe, Ca, Na, PO4 and Mn. Also in the synthetic Fe colloids PO4, Ca, Na and Mn were the most important elements next to Fe. Phosphate and dissolved organic C strongly influenced the morphology of the synthetic Fe colloids. When both the elemental composition and the morphology of the Fe colloids are taken into account, the synthetic Fe colloids formed in the synthetic solution containing Fe, Mn, PO4, SiO4 and dissolved organic matter best match the Fe colloids from the field

  4. Relationship between ecosystem respiration and aeration constant in open channel dissolved oxygen analysis

    Science.gov (United States)

    Parker, S. J.; Butler, A. P.; Heppell, C. M.

    2015-12-01

    Using the open channel diel method of Odum (1956) and the night-time regression method (Hornberger and Kelly, 1985), we analysed a time series of dissolved oxygen (DO) in two slow flowing streams for a two month period in summer 2014 and obtained values for ecosystem respiration and the aeration constant for each day in the period. We then used the standard dissolved oxygen lumped model to generate a DO time series behaviour for one of those rivers selecting respiration and aeration parameters by randomly sampling from the values obtained from the data. Two synthetic time series were created, one where respiration and aeration were independent of temperature and a second where respiration and aeration were affected by temperature according to the modified Arrhenius relationship. With these two synthetic time series, we again recovered the respiration and aeration input parameters using the night- time regression method and compared those recovered parameters with the input parameters. Because the simulations were conducted with parameters that were known, the values recovered using the night-time regression method (i.e post-simulation) could be compared with parameters driving the simulation (i.e. pre-simulation input values). For values based on data, we found a strong correlation between the aeration constant and respiration for both rivers. For the synthetic time series, no such correlation was found, either with the temperature independent or temperature dependent time series. The night-time regression method also recovered perfectly the input parameters, so the correlation was not brought about as a result of implementing the method itself. We are currently investigating the cause of the correlation.

  5. Factors Affecting the Oxygenation Capacity of Disc Aerators in an Oxidation Ditch System

    Directory of Open Access Journals (Sweden)

    Abdel E. Ghaly

    2011-01-01

    Full Text Available Problem statement: The use of aerobic biological methods for the treatment of livestock wastes has resulted in a proliferation of mechanical aeration devices to accomplish the desired treatment. The oxidation ditch system with disc aerators is among the aerobic systems that have been used to treat livestock waste. The main objectives of this study were to investigate the effects of various disc design parameters and system operational parameters on the oxygen transfer coefficient and to study the physical phenomenon of oxygen transfer using high speed movie techniques. Approach: A bench-scale oxidation ditch with a disc aerator was used to conduct a series of experiments to determine the effects of immersion depth (2.5-7.5 cm, disc speed (50-250 rpm, disc thickness (0.32-2.55 cm, hole diameter (0.00-1.92 cm and number of rotating discs (1-2 on the oxygen transfer coefficient. The unsteady state method with sodium sulfite oxidation was used to deoxygenate the water and the dissolved oxygen concentration was measured with time. Results: The disc speed had the most significant effect on KLa with the immersion depth and hole diameter both showing strong effects and the disc thickness showing less effect. The effect of adding a second disc was comparable to using a single disc of double the thickness at lower speeds while at speeds higher than 200 rpm doubling the thickness of a single disc had less effect than a second disc. Conclusion: The highest oxygen transfer (1.526 min-1 was achieved using two coaxial discs with a disc speed of 250 rpm, a disc thickness of 0.64 cm, a hole diameter of 1.92 cm and an immersion depth of 7.5 cm. Bubble aeration and eddy aeration were the most prevalent mechanisms of oxygen transfer in the oxidation ditch while surface aeration played a relatively small role in oxygen transfer.

  6. Volatile emissions during storing of green food waste under different aeration conditions.

    Science.gov (United States)

    Agapiou, A; Vamvakari, J P; Andrianopoulos, A; Pappa, A

    2016-05-01

    Controlled field experiments were carried out for monitoring the emissions of three plastic commercial household waste bins, which were adapted for studying the effect of aeration process in the evolved volatiles, during house storing of green food waste for 2 weeks, prior to collection. Three experimental scenarios were examined based on no aeration ("NA," closed commercial waste bin), diffusion-based aeration ("DA," closed commercial waste bin with tiny holes), and enforced aeration ("EA," closed commercial waste bin with tiny holes and enforced aeration). The monitoring of volatile organic compounds (VOCs) emitted from organic household kitchen waste was performed using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis. Portable sensors were also used for monitoring selected gases and parameters of environmental, bioprocess, and health interest (e.g., CO2, O2, H2S, CH4, NH3, % RH, waste temperatures). VOC emissions are strongly dependent on the waste material. The most frequent VOCs identified over the storing waste, showing over 50 % appearance in all examined samples, were terpenes (e.g., di-limonene, beta-myrcene, delta-3-carene, alpha-pinene, alpha-terpinolene, linalool, etc.), sulfides (dimethyl disulfide), aromatics (benzene, 1-methyl-2-(2-propenyl)), alkanes (e.g., decane, dodecane), ketones (2-propanone), esters (e.g., acetic acid ethyl ester, acetic acid methyl ester), and alcohols (e.g., 3-cyclohexen-1-ol, 4-methyl-1-(1-methylethyl)). The prominent role of terpenes in the "pre-compost" odor and especially that of di-limonene was highlighted. In all examined scenarios, the emitted volatiles were increased at raised temperatures and later decreased in time. Aeration of waste bins slightly affected the volatilization process resulting in higher profiles of VOCs; uniformity in the composition of VOCs was also noted. Slight modifications of commercial waste bins may favor the initiation of home composting. PMID

  7. Energy consumption of aeration systems in membrane activation systems; Energiebedarf von Belueftungseinrichtungen in Membranbelebungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Krause, S.; Cornel, P. [Inst. WAR, TU Darmstadt, Darmstadt (Germany)

    2003-07-01

    Owing to the necessity of aeration aggregates, membrane activation systems have higher energy consumption than conventional activation systems. The contribution investigates the energy demand of aeration systems for oxygen supply to the biomass and for control of precipitates on submerged membranes. (orig.) [German] Membranbelebungsanlagen (MBR) zeichnen sich durch einen feststofffreien Klaeranlagenablauf aus. Zudem koennen hoehere Feststoffgehalte im Belebungsbecken erzielt werden. Jedoch ist aufgrund der zusaetzlichen Belueftungsaggregate zur Deckschichtminimierung an den Membranen und reduzierter {alpha}-Werte der Energiebedarf hoeher als in konventionellen Belebungsanlagen. Nachstehend wird der Energiebedarf der Belueftungseinrichtungen zur Sauerstoffversorgung der Biomasse und zur Deckschichtkontrolle getauchter Membranen untersucht. (orig.)

  8. Protease obtention using Bacillus subtilis 3411 and amaranth seed meal medium at different aeration rates

    Directory of Open Access Journals (Sweden)

    Pastor Maria Delia

    2001-01-01

    Full Text Available The influence of the addition of Amaranthus cruenthus seed meal to the medium, as nutrient and growth factor, on protease production by Bacillus subtilis 3411 was studied. Tests were carried out in a rotary shaker and in mechanically stirred fermenters. The influence of aeration was also evaluated. The addition of amaranth in a concentration of 20 g/L resulted in 400% increase in protease production. Aeration up to 750 r.p.m. and 1 L/L.min had a favorable effect.

  9. Production of Candida utilis Biomass and Intracellular Protein Content: Effect of Agitation Speed and Aeration Rate

    OpenAIRE

    Rosma, A.; Ooi, K. I.

    2006-01-01

    The effects of agitation speed and aeration rate on the Candida utilis biomass and the intracellular protein content were investigated in this study. C. utilis inoculum of 10^6 cells/mL (7.8 % v/v) was cultured in 1.5 L pineapple waste medium (3 % Brix) in a 2-L fermentor for 30 h at 30 °C. Agitation speed and aeration rate have significant effects on the dissolved oxygen concentration, which in turn affect the cell growth and the intracellular protein content. The agitation speed of 100, 300...

  10. Effects of Soil Aeration on Sweet Potato Yield and Its Physiological Mechanism

    Institute of Scientific and Technical Information of China (English)

    SHI Chun-yu; WANG Zhen-lin; YU Song-lie

    2002-01-01

    The effects of soil aeration on physiological characters and root tuber yield of Ipomoea batatas (L.) Lam. CV Lushu7 and Xushu18 were studied. The results showed that soil aeration improvement could increase ATP content and ATPase activity in functional leaves and root tubers and ABA content in root tubers.It also accelerated the transportation of 14C-photosynthate from leaves to root tubers and enhanced dry matter distribution in root tubers and thus root tuber yield was significantly raised. The role of ATP, ATPase and ABA in accelerating the transportation of 14C-photosynthate was discussed based on the changes of soluble carbonhydrate content in sweet potato plant.

  11. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark;

    2014-01-01

    -stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O) and...... conditions where anaerobic exceeds aerobic ammonium oxidation activity is proposed to minimize N2O emissions from single-stage nitritation/anammox reactors; increasing the frequency of aeration cycling is an efficient way of obtaining those conditions....

  12. Pathways of nitrobenzene degradation in horizontal subsurface flow constructed wetlands: Effect of intermittent aeration and glucose addition.

    Science.gov (United States)

    Kirui, Wesley K; Wu, Shubiao; Kizito, Simon; Carvalho, Pedro N; Dong, Renjie

    2016-01-15

    Intermittent aeration and addition of glucose were applied to horizontal subsurface flow constructed wetlands in order to investigate the effect on pathways of nitrobenzene (NB) degradation and interactions with microbial nitrogen and sulphur transformations. The experiment was carried out in three phases A, B and C consisting of different NB loading and glucose dosing. For each phase, the effect of aeration was assessed by intermittently aerating one wetland and leaving one unaerated. Regardless of whether or not the wetland was aerated, at an influent NB concentration of 140 mg/L, both wetlands significantly reduced NB to less than 2 mg/L, a reduction efficiency of 98%. However, once the influent NB concentration was increased to 280 mg/L, the aerated wetland had a higher removal performance 82% compared to that of the unaerated wetland 71%. Addition of glucose further intensified the NB removal to 95% in the aerated wetlands and 92% in the unaerated. Aeration of wetlands enhanced NB degradation, but also resulted in higher NB volatilization of 6 mg m(-2) d(-1). The detected high concentration of sulphide 20-60 mg/L in the unaerated wetland gave a strong indication that NB may act as an electron donor to sulphate-reducing bacteria, but this should be further investigated. Aeration positively improved NB removal in constructed wetlands, but resulted in higher NB volatilization. Glucose addition induced co-metabolism to enhance NB degradation. PMID:26468606

  13. Influence of aeration of Candida albicans during culturing on their surface aggregation in the presence of adhering Streptococcus gordonii

    NARCIS (Netherlands)

    Millsap, KW; van der Mei, HC; Busscher, HJ; Bos, R.R.M.

    1999-01-01

    Candida albicans surfaces are extremely sensitive to changes in growth conditions. In this study, adhesion to glass of aerated and non-aerated C. albicans ATCC 10261 in the presence and absence of adhering Streptococcus gordonii NCTC 7869 was determined in a parallel plate flow chamber. In addition,

  14. Performance of organics and nitrogen removal in subsurface wastewater infiltration systems by intermittent aeration and shunt distributing wastewater.

    Science.gov (United States)

    Pan, Jing; Yuan, Fang; Yu, Long; Huang, Linli; Fei, Hexin; Cheng, Fan; Zhang, Qi

    2016-07-01

    Organics and nitrogen removal in four subsurface wastewater infiltration systems (SWISs), named SWIS A (without intermittent aeration and shunt distributing wastewater), SWIS B (with intermittent aeration), SWIS C (with shunt distributing wastewater) and SWIS D (with intermittent aeration and shunt distributing wastewater) was investigated. High average removal rates of 92.3% for COD, 90.2% for NH4-N and 88.1% for TN were achieved simultaneously in SWIS D compared with SWIS A, B and C. The excellent TN removal of SWIS D was due to intermittent aeration provided sufficient oxygen for nitrification in upper matrix and the favorable anoxic or anaerobic environment for denitrification in subsequent matrix, and moreover, shunt distributing wastewater provided sufficient carbon source for denitrification process. The results indicated that intermittent artificial aeration combined with shunt distributing wastewater could achieve high organics and nitrogen removal in SWISs. PMID:27039353

  15. Nitrification cessation and recovery in an aerated saturated vertical subsurface flow treatment wetland: Field studies and microscale biofilm modeling.

    Science.gov (United States)

    Murphy, Clodagh; Rajabzadeh, Amin R; Weber, Kela P; Nivala, Jaime; Wallace, Scott D; Cooper, David J

    2016-06-01

    In aerated treatment wetlands, oxygen availability is not a limiting factor in sustaining a high level of nitrification in wastewater treatment. In the case of an air blower failure, nitrification would cease, potentially causing adverse effects to the nitrifying bacteria. A field trial was completed investigating nitrification loss when aeration is switched off, and the system recovery rate after the aeration is switched back on. Loss of dissolved oxygen was observed to be more rapid than loss of nitrification. Nitrate was observed in the effluent long after the aeration was switched off (48h+). A complementary modeling study predicted nitrate diffusion out of biofilm over a 48h period. After two weeks of no aeration in the established system, nitrification recovered within two days, whereas nitrification establishment in a new system was previously observed to require 20-45days. These results suggest that once established resident nitrifying microbial communities are quite robust. PMID:26967335

  16. Aeration control in a full-scale activated sludge wastewater treatment plant: impact on performances, energy consumption and N2O emission

    OpenAIRE

    Filali, A.; Fayolle, Y.; Peu, P.; Philippe, L.; Nauleau, F.; Gillot, S.

    2013-01-01

    International audience This work investigated the impact of aeration control strategy on energy consumption and nitrous oxide (N2O) emission in a full-scale wastewater treatment plant. Two identical activated sludge processes treating the same effluent but operated with different aeration control strategies were compared. Aeration tank 1 was operated with a new control strategy favouring the simultaneous nitrification denitrification (SND) whereas aeration tank 2 was operated with a conven...

  17. Biofiltration of Methane from Ruminants Gas Effluent Using Autoclaved Aerated Concrete as the Carrier Material

    NARCIS (Netherlands)

    Ganendra, Giovanni; Mercado-Garcia, Daniel; Hernandez-Sanabria, Emma; Peiren, Nico; De Campeneere, Sam; Ho, Adrian; Boon, Nico

    2015-01-01

    Abstract The performance of Methane-Oxidizing Bacteria (MOB) immobilized on Autoclaved Aerated Concrete (AAC) in a biofilter setup to remove methane from ruminants gas effluent was investigated. Two dairy cows were housed in respiration chambers for two days where the exhaust gas from the chambers w

  18. Comparative Study of Nirmalya Solid Waste Treatment by Vermicomposting and Artificial Aeration Composting

    Directory of Open Access Journals (Sweden)

    Pallavi S.Chakole

    2014-08-01

    Full Text Available Temple waste normally contains floral offering, leaves and milk product i.e. “Abishek waste water”, and this solid waste management is one of the important issues in the world, because of shortage ofdumping sites and strict environmental legislation. Now days ‘Nirmalyasolid waste’ is generated in large quantity due toincreased in population are commonly treated using different types of bins by the method of composting or vermicomposting. Vermicomposting of solid waste can be done by using different types of earthworms providing natural and artificial aeration along with mixture of cow dung and soil, artificial aeration is carried out by providing diffused aerators or perforated pipes. The parameters like C/N ratio, temperature, moisture contain are carried out. The main objective of this study is to minimize the problem of solid waste management by treating nirmalya solid waste by vermicomposting and suggesting that which method gives good quality of compost at short interval of time comparing artificial and natural aeration composting.

  19. Investigation of aeration rate on Uranium bio leaching in internal airlift bioreactor

    International Nuclear Information System (INIS)

    Uranium is leached from the uranium ore of the second anomaly of Saghand by the Acidithiobacillus ferroxidans bacteria in an internal airlift bio-reactor. This study has been made to find the effect of aeration rate as well as its optimal value. The experiments have been carried out at 4 aeration rates to find the best recovery results in the least possible time duration. The results showed that the most percentage of the uranium recovery is in the superficial gas velocity of 0.010 m/s. The recovery at this aeration rate has an efficiency of more than 95percentin 11 days. Also, the best range for aeration study in the airlift bio-reactor is calculated with a minimum value of 0.0065 m/s which is the critical value of the uranium particle suspension as well as the maximum value of 0.015 m/s. The stress on the bacteria increases the recovery time process in velocities of more than 0.015 m/s.

  20. Gas transfer rates from airlifts used for concurrent aeration, carbon dioxide stripping, and recirculation

    Science.gov (United States)

    Airlifts simplify recirculating aquaculture systems and can potentially reduce capital costs and minimize maintenance issues. Airlifts have the ability to move and aerate water as well as degass the water of any carbon dioxide. This study evaluated the oxygen transfer and carbon dioxide removal abil...

  1. Combination of methoprene and controlled aeration to manage insects in stored wheat

    Science.gov (United States)

    The insect growth regulator methoprene, in the commercial formulation Diacon II®, was applied to wheat stored in small bins either alone or in combination with controlled aeration of the bins to lower grain temperature for insect pest management of stored wheat. Grain temperatures and monitored and ...

  2. Evaluation of cost-effective aeration technology solutions to address total trihalomethane (TTHM) compliance

    Science.gov (United States)

    The primary objective of this project was to evaluate cost-effective aeration technology solutions to address TTHM compliance at a water treatment plant clearwell. The project team worked closely with EPA Region 6 and the EPA Office of Research and Development (ORD) to identify a...

  3. Removal of arsenic from contaminated groundwater with application of iron electrodissolution, aeration and sand filtration

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Arturi, Kasia; Søgaard, Erik Gydesen

    2014-01-01

    The results from a new water treatment system for arsenic removal are presented. The technology is based on the employment of an electrolytic iron dissolution and efficient aeration procedure prior to sand filtration. The treatment was introduced and investigated in a pilot scale plant and full...

  4. The initial behaviour of freshly etched copper in modertely acid, aerated chloride solutions

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Jaskula, M.; Chorkendorff, Ib;

    2002-01-01

    When freshly etched samples of various types of copper were exposed in moderately acid, aerated chloride solutions, two phenomena were observed. First the corrosion potential and the pH of the solution decreased over a shorter time, then the potential increased over a long period (600-1500 min...

  5. Flow, aeration, and carbon dioxide transfer rates for airlifts used in recirculating aquaculture systems

    Science.gov (United States)

    Airlift pumping systems reduce the electrical costs of moving water in a recirculating aquaculture system and can be concurrently designed to aerate water and remove carbon dioxide. This study determined the water flow, oxygen transfer, and CO2 removal rates for water using airlift technology in a 1...

  6. A STUDY OF THE DISCHARGE OF COHESIVE POWDERS UNDER SIMULTANEOUS AERATION AND VIBRATION

    NARCIS (Netherlands)

    Marring, E.; Hoffmann, A.C; Janssen, L.P.B.M.

    1995-01-01

    The influence of applying simultaneous aeration and vibration on the discharge of cohesive powders from a laboratory scale cylindrical silo has been studied experimentally. The powders investigated were batches of potato starch powder of different moisture contents and therefore different degrees of

  7. Effects of Aeration on Root Physiology and Nitrogen Metabolism in Rice

    Institute of Scientific and Technical Information of China (English)

    XU Chun-mei; WANG Dan-ying; CHEN Song; CHEN Li-ping; ZHANG Xiu-fu

    2013-01-01

    In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth,the activities of glutamine synthetase (GS),glutamic acid-pyruvic acid transaminase (GPT) and glutamic acid oxaloacetate transaminase (GOT),the nitrate (NO3-N) concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.

  8. Effect of the aerated structure on selected properties of freeze-dried hydrocolloid gels

    Science.gov (United States)

    Ciurzyńska, Agnieszka; Lenart, Andrzej

    2016-01-01

    The ability to create diverse structures and studies on the effect of the aerated structure on selected properties with the use of freeze-dried gels may provide knowledge about the properties of dried foods. Such gels can be a basis for obtaining innovative food products. For the gel preparation, 3 types of hydrocolloids were used: low-methoxyl pectin, a mixture of xanthan gum and locust-bean gum, and a mixture of xanthan gum and guar gum. Gels were aerated for 3 and 7 min, frozen at a temperature of -45°C 2 h-1, and freeze-dried at a temperature of 30°C. For the samples obtained, structure, porosity, shrinkage, rehydration, and colour were investigated. It was shown that the type of the hydrocolloid and aeration time influence the structure of freeze-dried gels, which determines such properties of samples as porosity, shrinkage, density, rehydration, and colour. The bigger pores of low-methoxyl pectin gels undergo rehydration in the highest degree. The delicate and aerated structure of gels with the mixture of xanthan gum and locust-bean gum was damaged during freeze-drying and shrinkage exhibited the highest value. Small pores of samples with the mixture of xanthan gum and guar gum were responsible for the lower rehydration properties, but the highest porosity value contributed to the highest lightness value.

  9. Effects of overlying water aeration on phosphorus fractions and alkaline phosphatase activity in surface sediment

    Institute of Scientific and Technical Information of China (English)

    Jianjun Chen; Shaoyong Lu; Yikun Zhao; Wei Wang; Minsheng Huang

    2011-01-01

    Microbial activity may influence phosphorus (P) deposit and release at the water sediment interface.The properties of DO (dissolved oxygen), pH, P fractions (TP, Ca-P, Fe-P, OP, IP), and APA (alkaline phosphatase activity) at the water sediment interface were measured to investigate microbial activity variations in surface sediment under conditions of two-month intermittent aeration in overlying water.Results showed that DO and TP of overlying water increased rapidly in the first week and then decreased gradually after 15 day of intermittent aeration.Microorganism metabolism in surface sediment increased pH and decreased DO and TP in the overlying water.After two-month intermittent aeration, APA and OP from surface sediment (0-2 crm) were both significantly higher than those from bottom sediment (6-8 cm) (p < 0.05), and surface sediment Fe-P was transferred to OP during the course of microorganism reproduction on the surface sediment.These results suggest that microbial activity and microorganism biomass from the surface sediment were higher than those from bottom sediment afar two-month intermittent aeration in the overlying water.

  10. Use of a web-based model for aeration management in stored rough rice

    Science.gov (United States)

    A web-based model was used to simulate the impact of aeration on population growth of the lesser grain borer, Rhyzopertha dominica (F.), and the rice weevil, Sitophilus oryzae (L.), in stored rough rice at Beaumont, TX, USA. Simulations were run for each of 10 years with 1 August as the start date, ...

  11. Processes to improve energy efficiency during pumping and aeration of recirculating water in circular tank systems

    Science.gov (United States)

    Conventional gas transfer technologies for aquaculture systems occupy a large amount of space, require considerable capital investment, and can contribute to high electricity demand. In addition, diffused aeration in a circular tank can interfere with the hydrodynamics of water rotation and the spee...

  12. Start-up strategies of membrane-aerated biofilm reactor (MABR) for completely autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Sun, Sheng-Peng; Pellicer i Nàcher, Carles; Terada, Akihiko;

    2009-01-01

    downside of this process stems from a long start-up period due to the slow growth rate of AnAOB. Therefore, two different start-up strategies, i.e., continuous inoculation of AnAOB and sequential batch inoculation of AOB and AnAOB, were tested in two laboratory scale membrane-aerated biofilm reactor (MABRs...

  13. Optimization of micro-aeration intensity in acidogenic reactor of a two-phase anaerobic digester treating food waste

    International Nuclear Information System (INIS)

    Highlights: • Effect of micro-aeration on acidogenesis and hydrolysis of food waste was investigated. • Micro-aeration at 258 L-air/kg TS/d increased the VFAs production 3-fold. • High aeration leads to loss of substrate through microbial biomass and respiration. • Optimum aeration increased methane recovery while high aeration intensity reduced methane yield. - Abstract: Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35 °C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21–27% and 38–64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH4/g VSadded in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO2 respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste

  14. Impact of intermittent aerations on leachate quality and greenhouse gas reduction in the aerobic-anaerobic landfill method.

    Science.gov (United States)

    Nag, Mitali; Shimaoka, Takayuki; Komiya, Teppei

    2016-09-01

    The aerobic-anaerobic landfill method (AALM) is a novel approach in solid waste management that could shorten the landfill post-closure period and minimize the environmental loads. In this study, the aerobic-anaerobic landfill method was evaluated by using intermittent aeration. In addition, the nitrification-denitrification process was assessed as a means of reducing the emission of greenhouse gases (GHGs) and improving the leachate quality during the degradation of the organic solid waste. The leachate quality and the gas composition in each of the reactors were measured during the experimental period (408days). The aeration process entailed the injection of air into plexiglass cylinders (200cm height×10 cm diameter), filled with fresh organic solid waste collected from a composting plant. Different aeration routines were applied, namely, continuous aeration (aerobic reactor A), aeration for three days/week (aerobic-anaerobic reactor B), aeration for 6h/day (aerobic-anaerobic reactor C), and no aeration (non-aerated reactor D). It was found that aerobic reactor A produced the best results in terms of reduction of GHGs and improvement of the leachate quality. The aerobic-anaerobic reactor C was found to be more effective than reactor B in respect of both the emission of GHGs and the leachate quality; moreover, compared with aerobic reactor A, energy costs were reduced by operating this reactor. The transition period phenomenon was investigated during an intensive seven-day experiment conducted on the discharged leachate obtained from aerobic-anaerobic reactors B and C. The experiment concerned the differences in the composition of the gas during the aeration and the non-aeration periods. It was found that the transition period between the aeration and non-aeration cycles, which followed the simultaneous nitrification-denitrification had a considerable effect on the leachate quality of both the reactors. The results indicated that AALM has the potential to reduce

  15. Numerical and experimental investigation of the self-inducing turbine aeration capacity

    International Nuclear Information System (INIS)

    Highlights: • Numerical and experimental study of kLa coefficient of a self-inducing turbine. • Validation of experimental results. • Numerical study of kLa variation with the variation of impeller submersion and blade inclination. • Numerical study of the flow field and hydrodynamic parameters. - Abstract: Self-inducing turbines are a model of mixers that ensure the aeration of a fluid field without using a sparger and a surface aerator. Nevertheless, this type of turbines remain quite complicated in terms of behavior of the fluid within the tank, and its actual aeration capacity varies depending on the type of turbine used. The studied turbine is self-inducing and made of three blades and each blade contains five holes. In this work, we evaluated experimentally – using the technique of dynamic oxygenation and deoxygenating – the aeration capacity of our impeller by calculating the volumetric mass transfer coefficient kLa for various submergences and various inclination angles of the blade. This work was then validated by a numerical modeling using the commercial code Fluent, and the flow within the tank as well as the evolution of the hydrodynamic parameters was also studied. The simulation is steady state with a VOF multiphase model and the realizable k–ε turbulence model. We finally concluded that kLa decreases with the increase of the inclination angle and with the increase of the submergence of our turbine. We could also study the hydrodynamic parameters of the flow such as the power number, the aeration number and the shear rate

  16. Combination of Methoprene and Controlled Aeration to Manage Insects in Stored Wheat

    Directory of Open Access Journals (Sweden)

    Samuel S. Liu

    2016-06-01

    Full Text Available A commercial formulation of the insect growth regulator methoprene was applied to wheat stored in small bins either alone or in combination with controlled aeration of the bins, to lower grain temperature for insect pest management of stored wheat. Grain temperatures were monitored and modified by a computer-controlled thermocouple system that also activated the aeration system at programmed set-points to move cool ambient air through the grain mass to lower grain temperature. Results from sampling insect populations in experimental storage bins along with laboratory mortality bioassays of insects placed on wheat taken from the bins over the course of the storage period showed that methoprene was very effective in controlling infestation by the externally-feeding stored grain insects Plodia interpunctella (Hübner, the Indian meal moth Tribolium castaneum (Herbst, the red flour beetle, Cryptolestes ferrugineus (Stephens, the rusty grain beetle, and also for the internal-feeding pest Rhyzopertha dominica( Fauvel, the lesser grain borer. Methoprene did not give good control of the internal-feeding pest Sitophilus oryzae (L., the rice weevil. Aeration alone was somewhat effective in suppressing insect population development, while methoprene alone or when combined with aeration greatly enhanced insect control. Commercial grain grading for industry quality standards at the end of the storage period confirmed the impact of insect suppression on maintaining high quality of the stored wheat. This field experiment shows that methoprene combined with aeration to cool grain can be effective for pest management of stored wheat in the southern plains of the United States of America.

  17. Combination of Methoprene and Controlled Aeration to Manage Insects in Stored Wheat.

    Science.gov (United States)

    Liu, Samuel S; Arthur, Frank H; VanGundy, Douglas; Phillips, Thomas W

    2016-01-01

    A commercial formulation of the insect growth regulator methoprene was applied to wheat stored in small bins either alone or in combination with controlled aeration of the bins, to lower grain temperature for insect pest management of stored wheat. Grain temperatures were monitored and modified by a computer-controlled thermocouple system that also activated the aeration system at programmed set-points to move cool ambient air through the grain mass to lower grain temperature. Results from sampling insect populations in experimental storage bins along with laboratory mortality bioassays of insects placed on wheat taken from the bins over the course of the storage period showed that methoprene was very effective in controlling infestation by the externally-feeding stored grain insects Plodia interpunctella (Hübner), the Indian meal moth Tribolium castaneum (Herbst), the red flour beetle, Cryptolestes ferrugineus (Stephens), the rusty grain beetle, and also for the internal-feeding pest Rhyzopertha dominica( Fauvel), the lesser grain borer. Methoprene did not give good control of the internal-feeding pest Sitophilus oryzae (L.), the rice weevil. Aeration alone was somewhat effective in suppressing insect population development, while methoprene alone or when combined with aeration greatly enhanced insect control. Commercial grain grading for industry quality standards at the end of the storage period confirmed the impact of insect suppression on maintaining high quality of the stored wheat. This field experiment shows that methoprene combined with aeration to cool grain can be effective for pest management of stored wheat in the southern plains of the United States of America. PMID:27322331

  18. [Effect of Aeration Strategies on Emissions of Nitrogenous Gases and Methane During Sludge Bio-Drying].

    Science.gov (United States)

    Qi, Lu; Wei, Yuan-song; Zhang, Jun-ya; Zhao, Chen-yang; Cai, Xing; Zhang, Yuan-li; Shao, Chun-yan; Li, Hong-mei

    2016-01-15

    The data on nitrogen gas (NH3, N2O, NO) emissions during sludge bio-drying process in China is scarce, especially NO due to its unstable chemical property. In this study, effect of two aeration modes on emissions of methane and nitrogenous gas was compared during the continuous aerated turning pile sludge bio-drying process at full scale. In these two aeration strategies, the one currently used in the plant was set as the control, and the other was set as the test in which the aeration was used for oxygen supply, pile temperature control, and moisture removal in the start-up, middle and final stages, respectively. The results showed that the aeration strategy used in the test could not only obviously accelerate the rate of sludge drying (the moisture contents of the test and the control were 36.6% and 42% on day 11) , but also had a better drying performance (the final moisture contents of the test and the control were 33.6% and 37.6%, respectively) and decreased the ammonia cumulative emission by 5%, (ammonia cumulative emission of the test and the control were 208 mg x m(-3) and 219.8 mg x m(-3), respectively). Though a lower accumulated emission (eCO2) of greenhouse gas in the test at 3.61 kg x t(-1) was observed than that of the control (3.73 kg x t(-1) dry weight) , the cumulative emission of NO in the test at 1.9 g x m(-2) was 15. 9% higher than that of the control (1.6 g x m(-2)). PMID:27078979

  19. Intensified organics and nitrogen removal in the intermittent-aerated constructed wetland using a novel sludge-ceramsite as substrate.

    Science.gov (United States)

    Wu, Haiming; Fan, Jinlin; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Liang, Shuang; Lv, Jialong; Lu, Shaoyong; Wu, Weizhong; Wu, Suqing

    2016-06-01

    In this study, a novel sludge-ceramsite was applied as main substrate in intermittent-aerated subsurface flow constructed wetlands (SSF CWs) for treating decentralized domestic wastewater, and intensified organics and nitrogen removal in different SSF CWs (with and without intermittent aeration, with and without sludge-ceramsite substrate) were evaluated. High removal of 97.2% COD, 98.9% NH4(+)-N and 85.8% TN were obtained simultaneously in the intermittent-aerated CW system using sludge-ceramsite substrate compared with non-aerated CWs. Moreover, results from fluorescence in situ hybridization (FISH) analysis revealed that the growth of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the intermittent-aerated CW system with sludge-ceramsite substrate was enhanced, thus indicating that the application of intermittent aeration and sludge-ceramsite plays an important role in nitrogen transformations. These results suggest that a combination of intermittent aeration and sludge-ceramsite substrate is reliable to enhance the treatment performance in SSF CWs. PMID:26832393

  20. Hydraulic characteristics of converse curvature section and aerator in high-head and large discharge spillway tunnel

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower project.In this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,etc.in the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3 as a platform and combining the k-model and VOF method.The flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical simulation.It indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the curve.It also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side wall.By means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m/s is proposed.

  1. Experimental Investigation on the Impact of Aeration Rate and Stirrer Speed on Micro-Aerobic Batch Fermentation

    OpenAIRE

    L.W.T. Emily; J. Nandong; Y. Samyudia

    2009-01-01

    The impact of aeration rate and stirrer speed on micro-aerobic fermentation is studied at laboratory scale. Result suggests that with Baker’s yeast, an increase in aeration rates from very low value can improve bioethanol productivity and yield because it can enhance cell viability. At constant stirrer speed of 150 rpm, the increase in aeration rate from 1 to 1.5 LPM leads to proportional increase in peak Oxygen Uptake Rate (OUR) from 600 to 1000 mM L-1 h. This increase coincides with the inc...

  2. Characterization of a hydraulic flow in the aeration tanks of Suzano wastewater treatment by using radioactive tracer, Sao Paulo State, Brazil

    International Nuclear Information System (INIS)

    Previous studies carried out by Suzano's Wastewater Treatment Station staff responsible for its operation and optimization indicated a mixing efficiency reduction of the existing aeration system, (Filstar superficial mechanical aerator). In this work instantaneous injection of radioactive tracer, bromine-82, was used in order to determine the mean residence time - MRT and dispersion numbers, in actual scale, with the objective of verifying the hydraulic flow behavior and the possible existence of dead zones in the Suzano Station aeration tanks, operating with different aeration systems: ABS submersible aerators, Frings System (tank A) and Filstar aerators (tank D). The obtained results showed that all essayed tanks have their hydraulic flow modeled by only one mixed reactor with dispersion numbers close to 1,0 ( 0,9473 and 0,9403 respectively ), and did not present dead zones. The best homogenization was reached in tank A operated with ABS aerators. (author)

  3. Ammonia-based intermittent aeration control optimized for efficient nitrogen removal.

    Science.gov (United States)

    Regmi, Pusker; Bunce, Ryder; Miller, Mark W; Park, Hongkeun; Chandran, Kartik; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

    2015-10-01

    This work describes the development of an intermittently aerated pilot-scale process (V = 0.45 m(3) ) operated for optimized efficient nitrogen removal in terms of volume, supplemental carbon and alkalinity requirements. The intermittent aeration pattern was controlled using a strategy based on effluent ammonia concentration set-points. The unique feature of the ammonia-based aeration control was that a fixed dissolved oxygen (DO) set-point was used and the length of the aerobic and anoxic time (anoxic time ≥25% of total cycle time) were changed based on the effluent ammonia concentration. Unlike continuously aerated ammonia-based aeration control strategies, this approach offered control over the aerobic solids retention time (SRT) to deal with fluctuating ammonia loading without solely relying on changes to the total SRT. This approach allowed the system to be operated at a total SRT with a small safety factor. The benefits of operating at an aggressive SRT were reduced hydraulic retention time (HRT) for nitrogen removal. As a result of such an operation, nitrite oxidizing bacteria (NOB) out-selection was also obtained (ammonia oxidizing bacteria [AOB] maximum activity: 400 ± 79 mgN/L/d, NOB maximum activity: 257 ± 133 mgN/L/d, P < 0.001) expanding opportunities for short-cut nitrogen removal. The pilot demonstrated a total inorganic nitrogen (TIN) removal rate of 95 ± 30 mgN/L/d at an influent chemical oxygen demand: ammonia (COD/NH4 (+) -N) ratio of 10.2 ± 2.2 at 25°C within the hydraulic retention time (HRT) of 4 h and within a total SRT of 5-10 days. The TIN removal efficiency up to 91% was observed during the study, while effluent TIN was 9.6 ± 4.4 mgN/L. Therefore, this pilot-scale study demonstrates that application of the proposed on-line aeration control is capable of relatively high nitrogen removal without supplemental carbon and alkalinity addition at a low HRT. PMID:26058705

  4. Effects of soil aeration, legume residue, and soil texture on transformations of macro- and micronutrients in soils. [Vicia villosa

    Energy Technology Data Exchange (ETDEWEB)

    Walters, D.T.; Doran, J.W. (Univ. of Nebraska, Lincoln (United States)); Aulakh, M.S. (Punjab Agricultural Univ. (India))

    1992-02-01

    Soil aeration is an important factor controlling microbial activity, nutrient availability, and plant root growth. The authors investigated the effect of hairy vetch (Vicia villosa) addition to well aerated (60% water-filled pore space (WFPS)) and poorly aerated (90% WFPS) soils of varying texture on transformations of C, N, P, K, Ca, Mg, S, Zn, Mn, Fe, and Cu for a 30-d period. The results of this study imply that incorporation of easily decomposable residue may supply substantial amounts of nutrients to growing plants. Where soils remain wet for > 10 d, residues may create intensive reducing conditions and a several fold increase in available Fe, Mn, Cu, and P. Conversely, DTPA extractable Fe, Mn, and Cu can vary greatly within a few weeks depending on soil aeration status, residue management, time of sampling, and soil texture and may lead to erroneous indices of nutrient availability to plants.

  5. Settlement determination of operating moisture of autoclaved aerated concrete in different climatic zones

    Directory of Open Access Journals (Sweden)

    Pastushkov Pavel Pavlovich

    Full Text Available In the process of operation of buildings the moisture state of enveloping structures materials is changing depending on their construction features, properties of the material, temperature and moisture conditions in the premises, climatic conditions of the construction area. Moisture mode determines the operational properties of the enveloping structures of a building. It directly influences the thermal characteristics of enveloping structure and energy efficiency of the applied materials. The analysis of the methods for calculation of moisture behavior of enclosing structures is carried out. The research relevance of operational moisture of AAC is substantiated. Experimental studies and results of the sorption moisturizing and water vapor permeability of leading marks of aerated concrete are carried out. The authors offer the results of numerical calculations of the moisture behavior of aerated concrete in the walls with mark D400 with facade thermal insulation composite systems - with external plaster layers for different climatic zones of construction.

  6. Optimization of Energy Consumption and Mass Transfer Parameters in a Surface Aeration Vessel.

    Science.gov (United States)

    Mohammadpour, A; AkhavanBehabadi, M A; Ebrahimzadeh, M; Raisee, M; MajdiNasab, A R; Nosrati, M; Mousavi, S M

    2016-04-01

    This paper reports tests on a lab-scale surface aeration vessel was equipped with a Rushton turbine to examine its performance in terms of standard aeration efficiency (SAE), mixing time, and void fraction characteristics. These characteristics were investigated by tests using variations of rotor speed, impeller immersion depth, and water level. Results showed that variation of impeller immersion depth had a greater effect on the SAE compared to variation of water level. Moreover, the SAE increased with rotor speeds up to about 150 to 200 rpm and then decreased. In addition, void fraction improved by impeller immersion depth and rotor speed enhancement; however, mixing time and power number were reduced as rotor speed increased. According to the response surface methodology statistical optimizations, optimum values for rotor speed, impeller immersion depth, and water level were 168.90 rpm, 25 mm, and 30 cm, respectively, to achieve the maximum value of SAE. PMID:27131059

  7. Incidence of secondary aeration in confined flames of high pressure premixed atmospheric burner

    International Nuclear Information System (INIS)

    In this work an experimental study about the variables that affect the secondary aeration has been applied. The relationships with phenomena that affect the proper operation of the combustion chamber are discussed in detail. These phenomena are quenching, flame stabilization and the combustion product recirculation. A flexible combustion system developed to allow variations in the volume of combustion chamber, the area of secondary air entrance, the outlet of combustion products and the thermal output is presented. Also, the system could vary the inlet of primary air, though the study is carried out with maximal working area. The experimental setup allowed to compare and to find the influence of design parameters mentioned above on the secondary aeration and also to obtain the insight that the most important design parameters were combustion product outlet and the combustion intensity

  8. Performances of lateral flow biological aerated filter in treating domestic wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-jing; LONG Teng-rui; CAO Yan-xiao

    2006-01-01

    A new biological aerated filter--lateral flow biological aerated filter(LBAF) is developed.The effects of air/water ratio,hydraulic loading and the length of LBAF on pollutants removal efficiency are tested.The results show that under optimal technological conditions when hydraulic loading is 0.43 m3 m(2 h(1 and air/water ratio is 10:1,the average removal efficiencies of COD,SS,NH3-N,and TN reach 88.01%,95.18%,78.97% and 52.58%,respectively.An LBAF has a large pollutants handling capacity; is less liable to be blocked,and has a longer operation cycle in comparison with a traditional BAF.

  9. Management of microbial community composition, architecture and performance in autotrophic nitrogen removing bioreactors through aeration regimes

    DEFF Research Database (Denmark)

    Mutlu, A. Gizem

    Completely autotrophic nitrogen removal from nitrogen-rich wastewaters through the nitritation -plus- anaerobic ammonium oxidation processes can greatly reduce operational energy costs compared to traditional nitrogen removal processes. The footprint can be further reduced by process intensificat......Completely autotrophic nitrogen removal from nitrogen-rich wastewaters through the nitritation -plus- anaerobic ammonium oxidation processes can greatly reduce operational energy costs compared to traditional nitrogen removal processes. The footprint can be further reduced by process...... some of the collateral impacts could be isolated, increasing process understanding. It was demonstrated that aeration strategy can be used as a powerful tool to manipulate the microbial community composition, its architecture and reactor performance. We suggest operation via intermittent aeration with...

  10. Implementing the concept of «sustainable development» in ukraine by use autoclaved aerated concrete.

    OpenAIRE

    Brynzin, I. V.; Paruta, V. А.

    2015-01-01

    Purpose. Implementation of the concept of "sustainable development" in Ukraine by the use of autoclaved aerated concrete, in the construction of low- and high-rise buildings and structures. The article describes the main characteristics of autoclaved aerated concrete, from the stage of extraction of raw materials and ending with recycling stage. Justified a broad introduction to the construction industry. Methodology. The results are obtained in the form of an expert opinion by comparing the ...

  11. Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation

    OpenAIRE

    Kim, Min Jeong; Shim, Chang Ki; Kim, Yong Ki; Hong, Sung Jun; Park, Jong Ho; Han, Eun Jung; Kim, Jin Ho; Kim, Suk Chul

    2015-01-01

    This study investigated the chemical characteristics and microbial population during incubation of four kinds of aerated compost teas based on oriental medicinal herbs compost, vermicompost, rice straw compost, and mixtures of three composts (MOVR). It aimed to determine the effects of the aerated compost tea (ACT) based on MOVR on the growth promotion of red leaf lettuce, soybean and sweet corn. Findings showed that the pH level and EC of the compost tea slightly increased based on the incub...

  12. Improvement of Hydraulic and Water Quality Renovation Functions by Intermittent Aeration of Soil Treatment Areas in Onsite Wastewater Treatment Systems

    OpenAIRE

    David V. Kalen; Josef H. Görres; Patenaude, Erika L.; David A. Potts; George W. Loomis; Amador, José A.

    2010-01-01

    We tested intermittent aeration of the soil treatment area (STA) of onsite wastewater treatment systems (OWTS) for its ability to restore and maintain STA hydraulic flow and improve the water quality functions of conventional OWTS. Evaluation was conducted on hydraulically-failed conventional OWTS at three state-owned medical group homes in Washington County, RI, USA. Testing was conducted in two phases, with Phase I (before intermittent soil aeration (ISA)) comprising the first 6 months of t...

  13. Sludge reduction by direct addition of chlorine dioxide into a sequencing batch reactor under operational mode of repeatedly alternating aeration/non-aeration.

    Science.gov (United States)

    Peng, Hong; Liu, Weiyi; Li, Yuanmei; Xiao, Hong

    2015-01-01

    The effect of direct addition of chlorine dioxide (ClO2) into a repeatedly alternating aeration/non-aeration sequencing batch reactor (SBR) on its sludge reduction and process performance was investigated. The experimental results showed that the sludge reduction efficiency was 32.9% and the observed growth yield (Yobs) of SBR was 0.11 kg VSS (volatile suspended solids) /kg COD (chemical oxygen demand) for 80 days' operation at the optimum ClO2 dosage of 2.0 mg/g TSS (total suspended solids). It was speculated that cell lysis and cryptic growth, uncoupled metabolism and endogenous metabolism were jointly responsible for the sludge reduction in this study. COD, NH3-N, total nitrogen (TN) and total phosphorus (TP) in the effluent increased on average 29.47, 4.44, 1.97 and 0.05 mg/L, respectively. However, the effluent quality still satisfied the first-class B discharge standards for municipal wastewater treatment plants in China. In that case, the sludge maintained fine viability with the specific oxygen uptake rate (SOUR) being 14.47 mg O2/(g VSS·h) and demonstrated good settleability with the sludge volume index (SVI) being 116 mL/g. The extra cost of sludge reduction at the optimum ClO2 dosage was estimated to be 2.24 CNY (or 0.36 dollar)/kg dry sludge. PMID:26524444

  14. Aeration condition of a clayey oxisol under long-term no-tillage

    Directory of Open Access Journals (Sweden)

    Edner Betioli Junior

    2014-06-01

    Full Text Available The hypothesis of this study was that the absence of soil tillage in long-term no-tillage (NT systems can be detrimental to soil aeration. The objective was to assess the aeration condition of an Oxisol (Rhodic Ferrasol, very clayey texture (750 g kg-1 of clay; 200 g kg-1 of sand, after 30 years of cultivation under NT. The physical property soil air permeability (Ka is sensitive to changes in the soil pore system. Aside from Ka, the air-filled porosity (ε a and indices of pore continuity (K1 and N, derived from the relationship between Ka and εa, were used as indices of soil aeration. From the soil layers 0.0-0.1 and 0.1-0.2 m, 240 undisturbed samples were collected along a transect perpendicular to the crop rows, at three sampling positions: corn plant row (CR; center of the interrow (INT; and the equidistant point between CR and INT (PE. The properties Ka and εa were determined at soil matric potentials (Ψm of -2, -4, -6, -10, -30, and -50 kPa. Soil bulk density (BD was also determined. The results confirmed the hypothesis. In the 0.0-0.1 m layer, Ka, K1, N and Ψa were significantly greater and BD significantly lower in CR than at the other sampling positions. At a Ψm of -10 kPa, the Ka of CR was 6.9 and 8.4 times higher than in PE and INT, respectively, in the 0.0-0.1 m layer. The properties Ka, K1 and N were sensitive enough to detect changes in the pore system and their differences between the sampling positions demonstrated the importance of the spatial location for soil sampling. Tilling the crop rows provides better soil aeration under NT.

  15. Biogas purification using membrane micro-aeration: A mass transfer analysis

    Directory of Open Access Journals (Sweden)

    Wathsala Perera, Deshai Botheju, Rune Bakke

    2014-01-01

    Full Text Available When sulfur containing organic feedstocks undergo anaerobic digestion, sulfides are formed due to the biological activities of sulfur reducing bacteria. Presence of hydrogen sulfide (H2S negatively affects the usage of biogas and needs to be reduced to levels that depend on the intended biogas application. Conversion of sulfide to its oxidized forms can be carried out by aerobic chemolithotrophic bacteria consuming oxygen as the electron acceptor. Membrane micro-aeration is a recently developed reliable method of safely supplying oxygen into anaerobic digesters. In this study, mass transfer models are developed to represent diffusion and back diffusion of gases through tubular polydimethylsiloxane (PDMS membranes. The models are utilized to determine the required membrane area and length in order to supply the stoichiometric amount of oxygen for biologically oxidizing a given amount of sulfide feed into elemental sulfur. Penetration of oxygen and nitrogen into the digester and transfer of methane, carbon dioxide and hydrogen sulfide back into the membrane tube are analyzed using these mass transfer models. Circulating air or aerated water inside the membrane tube is considered as two alternatives for supplying micro-aeration to the digester. Literature digester performance and sulfide data are used for example calculations. The required membrane length depends on circulating water flow rates and dissolved oxygen concentrations when water is used inside the membrane. A considerable fraction of CO2 can also be removed from the biogas in this case. Circulating air inside the membrane is, however, more promising solution as it requires much less membrane area and thereby also causes insignificant methane loss. The proposed membrane micro-aeration technique cuts N2 biogas dilution in half compared to direct air purging for in-situ sulfide oxidation.

  16. EXPERIMENTAL STUDY ON THE GAS-LIQUID FLOW IN THE MEMBRANE MICROPORE AERATION BIOREACTOR

    OpenAIRE

    DONG LIU; ZHENG WANG; MIN-GUAN YANG

    2008-01-01

    Particle Image Velocimetry (PIV) has been developed to measure the typical two-phase flow of various work conditions in Membrane Micropore Aeration Bioreactor (MMAB). The fluid phase is separated out using image processing techniques, which provides accurate measurements for the Bioreactor’s flow field, and makes it possible for quantitative analysis of the momentum exchange, heat exchange and the process of micro-admixture. The experimental method PIV used in this paper can preferably measur...

  17. Electrochemical Oxidation Using BDD Anodes Combined with Biological Aerated Filter for Biotreated Coking Wastewater Treatment

    OpenAIRE

    Wang, C.R.; Hou, Z. F.; M. R. Zhang; J. Qi; Wang, J.

    2015-01-01

    Coking wastewater is characterized by poor biodegradability and high microorganism toxicity. Thus, it is difficult to meet Grade I of Integrated Wastewater Discharge Standard of China by biological treatment technology; specifically, COD cannot meet above standard due to containing refractory organics. A novel coupling reactor, electrochemical oxidation using BDD anodes and biological aerated filter (BAF), has been developed for carbon and nitrogen removal from biotreated coking wastewater, f...

  18. The Influence of Micropore Oxygen Aeration on the Pond Water Quality Environment

    Directory of Open Access Journals (Sweden)

    Xiao-Jiang Chen

    2013-11-01

    Full Text Available In order to know the effects of micropore oxygen aeration on the water quality and economic output, take each 3 of micropore oxygen aeration (experimental pond and impeller oxygenation (control pond to make the comparison, indexs of two different aeration methods water were detected from May, 2012 to October, 2012. Such as water temperature, dissolved oxygen, ammonia nitrogen and nitrite, phytoplankton, chemical oxygen demand (CODMn. Results showed that, (1 the indexes of the dissolved oxygen, ammonia nitrogen, chemical oxygen demand(CODMn and nitrite of the experimental pond are all superior to that of the control pond, of which the concentration of the dissolved oxygen of the experimental pond is 8.37 mg/L which is higher than that of the control pond (5.7 mg/L. And, (CODMn in the experimental pond is 7.54 mg/L, lower than that in the control pond (10.19 mg/L. The difference between the control pond and the experimental pond was statistically significant (p<0.01. The ammonia nitrogen of the experimental pond is 0.1 mg/L, obviously lower than the control pond (0.16 mg/L. Besides, the nitrite is 0.13 mg/L in the experimental pond, lower than that of the control pond (0.21 mg/L. (2 Compared with the control pond, the experimental pond has quite higher general abundance of algae, with about 5.69×108 ind/L. Yet, there is no obvious difference between them. (3 Compared to the impeller oxygenation, the micropore oxygen aeration technology can be better to increase the dissolved oxygen in the aquaculture pond and improve the water quality. However, there is no significant influence to the phytoplankton abundance and diversity.

  19. Recycling of autoclaved aerated concrete in floor screeds: Sulfate leaching reduction by ettringite formation

    OpenAIRE

    Bergmans, Jef; Nielsen, Peter; Snellings, Ruben; Broos, Kris

    2016-01-01

    Autoclaved aerated concrete (AAC) is a lightweight cellular concrete. Recycling AAC in concrete or unbound applications may cause problems because of high amounts of leachable sulfate. This study evaluates the recycling of AAC demolition waste as a replacement of sand in floor screed. The cement binder reacted with sulfate released from the AAC waste to form ettringite. Sulfate release was in line with ettringite solubility control and below leaching limits defined by Dutch environmental legi...

  20. Effect of Prone Position on Regional Shunt, Aeration, and Perfusion in Experimental Acute Lung Injury

    OpenAIRE

    Richter, Torsten; Bellani, Giacomo; Harris, R. Scott; Melo, Marcos F. Vidal; Winkler, Tilo; Venegas, Jose G.; Musch, Guido

    2005-01-01

    Rationale: The prone position is used to improve gas exchange in patients with acute respiratory distress syndrome. However, the regional mechanism by which the prone position improves gas exchange in acutely injured lungs is still incompletely defined. Methods: We used positron emission tomography imaging of [13N]nitrogen to assess the regional distribution of pulmonary shunt, aeration, perfusion, and ventilation in seven surfactant-depleted sheep in supine and prone positions. Results: In t...

  1. Bacterial leaching of Uranium as affected by aeration, culture filtrate and size of inoculum

    International Nuclear Information System (INIS)

    Microorganisms play an important role in leaching and accumulation of uranium and other heavy metals. Some parameters which affect the efficiency of microoganisms in recovering uranium were previously studied. In this study, the effect of aeration, culture filtrate and size of inoculum of five Iraqi iron oxidizing bacteria, on leaching of uranium from claystone were studied. As a results of experimentation conducted, no significant increase in uranium leached was detected as a function of increasing in the size of inoculum for all isolates

  2. Study of Aeration Performance of Open Channel Chutes Equipped with a Flip Bucket

    OpenAIRE

    EMİROĞLU, M. Emin

    2003-01-01

    An adequate supply of dissolved oxygen (DO) is essential for the survival of aquatic organisms. Hydraulic structures can increase DO levels by creating turbulent conditions where small air bubbles are carried into the bulk of the flow. The flip bucket on open channel chutes with mild slopes is a particular instance of this, although the aeration performance of such structures has not been studied in the laboratory and field. This paper considers flip bucket chutes with different inc...

  3. Temperature control of paddy bulk storage with aeration-thermosyphon heat pipe

    International Nuclear Information System (INIS)

    A technology of an aeration-thermosyphon heat pipe is developed for controlling paddy temperature in a paddy bulk silo. A prototype of paddy bulk storage of 1000 kg has a set of copper tubes with steel fins embedded in the paddy bed. The total heat transfer area of the tubes with fins is 16 m2. The tubes act as the evaporator of a thermosyphon heat pipe and absorb heat resulting from the paddy respiration. The thermosyphon has a total condenser area of 12.2 m2 that is exposed to ambient air. At the bottom of the silo, ambient air is fed upward through the paddy bed for the aeration. The initial moisture content of the paddy is around 12.8% wet basis. A mathematical model to predict the paddy bed temperature in the silo with the hybrid aeration-thermosyphon is developed, and the results agree very well with the experimental data. The operating period of its blower could be found from the simulation. The blower is on when the paddy bed temperature, T b, is over or equal to 28 deg. C and the difference temperature between the bed and the ambient, T d, is over or equal to 1 deg. C. The appropriate evaporator area should be over 8 m2. At the area of 8 m2, the operation time of the blower is 8-9% of the annual period compared with 30-40% for normal aeration alone. The monthly paddy bed temperature could be maintained between 24 and 27 deg. C under the climate of Chiang Mai, Thailand

  4. Characteristics of aeration properties of orthic luvisol from poland under different land use

    OpenAIRE

    Włodarczyk T.; Brzezińska M.; Przywara G.; Stępniewska Z.; Stępniewski W.

    2000-01-01

    The present publication comprises results of measurements of aeration status related to soil properties such as: oxygen diffusion coefficient (D/Do), oxygen diffusion rate (ODR), redox potential (Eh), dehydrogenase and catalase activities as well as Fe+2 content at the soil moisture tensions of 63, 159 and 500 hPa in the (Ap) surface and (E) subsurface horizons of 3 soil profiles of an Orthic Luvisol under different land use (forest, farm and ex- perimental field). Results of the invest...

  5. Excessive Paranasal Sinuses and Mastoid Aeration as a Possible Cause of Chronic Headache

    OpenAIRE

    Panagiotis Kousoulis; Jiannis Hajiioannou; Vassiliki Florou; Dimitrios Kretzas; George Korres

    2013-01-01

    The objective of this case report is to present a patient with chronic headache who was diagnosed with excessive aeration of all paranasal sinuses and mastoid air cells using computed tomography imaging. The volume and linear measurements of all of the cavities revealed values greater than the greatest values reported in the literature. To date, this is the second reported case of excessive enlargement of all paranasal sinuses and the first which includes the enlargement of the mastoid air ce...

  6. Turbine Aeration Design Software for Mitigating Adverse Environmental Impacts Resulting From Conventional Hydropower Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Gulliver, John S. [Univ. of Minnesota, Minneapolis, MN (United States)

    2015-03-01

    Conventional hydropower turbine aeration test-bed for computational routines and software tools for improving environmental mitigation technologies for conventional hydropower systems. In achieving this goal, we have partnered with Alstom, a global leader in energy technology development and United States power generation, with additional funding from the Initiative for Renewable Energy and the Environment (IREE) and the College of Science and Engineering (CSE) at the UMN

  7. DETERMINATION METHODOLOGY OF BIOMASS AND PAC AT AERATION UNIT IN PACT PROCESS

    OpenAIRE

    N.Jaffarzadeh; A. Mesdaghinja; S. Nasserj; M.Shariat; A. Messbah

    2000-01-01

    In this research using two pilot scale systems of activated sludge (AS) and powdered activated carbon technology (PACT), the soluble organic load removal efficiency was evaluated, for a synthetic wastewater with mono-ethylene glycol as carbon source. Also, the variations of biomass and PAC in each reactor were studied and the relative accuracy of differential ignition method for determining the amount of biomass and powdered activated carbon (combined in aeration unit of the PACT pilot) was i...

  8. A Trade Study of Two Membrane-Aerated Biological Water Processors

    Science.gov (United States)

    Allada, Ram; Lange, Kevin; Vega. Leticia; Roberts, Michael S.; Jackson, Andrew; Anderson, Molly; Pickering, Karen

    2011-01-01

    Biologically based systems are under evaluation as primary water processors for next generation life support systems due to their low power requirements and their inherent regenerative nature. This paper will summarize the results of two recent studies involving membrane aerated biological water processors and present results of a trade study comparing the two systems with regards to waste stream composition, nutrient loading and system design. Results of optimal configurations will be presented.

  9. Experimental Investigation on the Impact of Aeration Rate and Stirrer Speed on Micro-Aerobic Batch Fermentation

    Directory of Open Access Journals (Sweden)

    L.W.T. Emily

    2009-01-01

    Full Text Available The impact of aeration rate and stirrer speed on micro-aerobic fermentation is studied at laboratory scale. Result suggests that with Baker’s yeast, an increase in aeration rates from very low value can improve bioethanol productivity and yield because it can enhance cell viability. At constant stirrer speed of 150 rpm, the increase in aeration rate from 1 to 1.5 LPM leads to proportional increase in peak Oxygen Uptake Rate (OUR from 600 to 1000 mM L-1 h. This increase coincides with the increase in yield by 7.5%. Interestingly at constant aeration rate of 1.5 LPM, an increase in stirrer speed from 150 to 250 rpm leads to decrease in peak OUR from 1000 to 457 mM L-1 h but increase in yield by 64%. In conclusion, both stirrer speed and aeration rate are important factors which have complex impacts on hydrodynamics and microbial metabolism, which in turn affect productivity and yield. Further study using CFD modeling and simulation method is required to gain better insights into how aeration rate and stirrer speed affect metabolism via the mixing mechanisms in a bioreactor.

  10. A field study on phytoremediation of dredged sediment contaminated by heavy metals and nutrients: the impacts of sediment aeration.

    Science.gov (United States)

    Wu, Juan; Yang, Lihua; Zhong, Fei; Cheng, Shuiping

    2014-12-01

    Compared to traditional chemical or physical treatments, phytoremediation has proved to be a cost-effective and environmentally sound alternative for remediation of contaminated dredged sediment. A field study was conducted in a sediment disposal site predominantly colonized by Typha angustifolia under different sediment moisture conditions to estimate the phytoremediation effects of dredged sediment. The moisture content was 37.30 % and 48.27 % in aerated and waterlogged sediment, respectively. Total nitrogen (TN) content was higher in the waterlogged sediment than in the aerated sediment. The total Cd contents were lower in aerated sediment, which was mainly resulted from the lower exchangeable fraction of Cd. The bioaccumulation of P, Cu and Pb in T. angustifolia was promoted by waterlogging, and the belowground tissue concentrations and accumulation factors (AFs) of Cu were higher than that of other metals, which can be explained by that Cu is an essential micronutrient for plants. Consistent with many previous studies, T. angustifolia showed higher metal levels in roots than in above-ground tissues at both the sediment conditions. Due to the improved biomass produced in the aerated sediment, the removals of nutrients and the metals by plant harvest were higher from aerated sediment than from waterlogged sediment. It was indicated that maintaining the dredged sediment aerated can avoid release risk and plant uptake of metals, while the opposite management option can promote phytoextraction of these contaminants. PMID:25012206

  11. Effect of forced aeration on citric acid production by Aspergillus sp. mutants in SSF.

    Science.gov (United States)

    Rodrigues, Cristine; Vandenberghe, Luciana P S; Sturm, Wilerson; Dergint, Dario E A; Spier, Michele Rigon; de Carvalho, Júlio Cesar; Soccol, Carlos R

    2013-12-01

    Citric acid (CA) is one of the most important products of fermentation in the world. A great variety of agro-industrial residues can be used in solid state fermentation. Aspergillus niger parental strain (CCT 7716) and two strains obtained by mutagenesis (CCT 7717 and CCT 7718) were evaluated in Erlenmeyer flasks and glass columns using citric pulp (CP) as substrate/support, sugarcane molasses and methanol. Best results using glass columns (forced aeration) were found in the fourth day of fermentation: 278.4, 294.9 and 261.1 g CA/kg of dry CP with CCT 7716, CCT 7718 and CCT 7717, respectively. In Erlenmeyer flasks (aeration by diffusion) CA reached 410.7, 446.8 and 492.7 g CA/kg of dry CP with CCT 7716, CCT 7718 and CCT 7717, respectively. The aeration by diffusion improved CA production by the three strains. A data acquisition system specially developed for biotechnological processes analysis was used to perform the respirometric parameters measurement. PMID:23760557

  12. Experimental and theoretical analysis of tubular membrane aeration for Mammalian cell bioreactors.

    Science.gov (United States)

    Qi, Hanshi N; Goudar, Chetan T; Michaels, James D; Henzler, Hans-Jugen; Jovanovic, Goran N; Konstantinov, Konstantin B

    2003-01-01

    A combination of experimental and theoretical approaches was used to characterize the dynamics of oxygen transfer in a membrane-aerated bioreactor. Pressure profiles along the length of the membrane at varying entrance and exit pressures were determined by actual experimental measurements, unlike most previous studies that have relied solely on theoretical descriptions of the pressure profile in the tubing. The mass transfer coefficient, k(L)a, was also determined under these conditions and was found to be essentially independent of tubing exit pressure. Measurement of the tubing pressure profile coupled with estimation of k(L)a allowed for computation of the oxygen transfer rate (OTR) along the length of the tubing. A mathematical model that incorporated friction pressure loss and losses due to tubing bending was developed to describe the pressure and hence OTR characteristics of membrane-aerated systems. The applicability of the model was verified by testing it on experimentally measured pressure data, and in all cases the model accurately described experimental data. When tubing properties are known, the mathematical model presented in this study allows for a priori estimation of OTR profiles along the length of the tubing. This information is vital for optimal design and scale-up of membrane-aerated bioreactors for mammalian cell culture. PMID:12892480

  13. Treatment of sewage sludge in a thermophilic membrane reactor (TMR) with alternate aeration cycles.

    Science.gov (United States)

    Collivignarelli, Maria Cristina; Castagnola, Federico; Sordi, Marco; Bertanza, Giorgio

    2015-10-01

    The management of sewage sludge is becoming a more and more important issue, both at national and international level, in particular due to the uncertain recovery/disposal future options. Therefore, it is clear that the development of new technologies that can mitigate the problem at the source by reducing sludge production is necessary, such as the European Directive 2008/98/EC prescribes. This work shows the results obtained with a thermophilic membrane reactor, for processing a biological sludge derived from a wastewater treatment plant (WWTP) that treats urban and industrial wastewater. Sewage sludge was treated in a thermophilic membrane reactor (TMR), at pilot-scale (1 m(3) volume), with alternate aeration cycles. The experimentation was divided into two phases: a "startup phase" during which, starting with a psychrophilic/mesophilic biomass, thermophilic conditions were progressively reached, while feeding a highly biodegradable substrate; the obtained thermophilic biomass was then used, in the "regime phase", to digest biological sludge which was fed to the plant. Good removal yields were observed: 64% and 57% for volatile solids (VS) and total COD (CODtot), respectively, with an average hydraulic retention time (HRT) equal to 20 d, an organic loading rate (OLR) of about 1.4-1.8 kg COD m(-3) d(-1) and aeration/non aeration cycles alternated every 4 h. PMID:26233586

  14. Impacts of aeration and active sludge addition on leachate recirculation bioreactor

    International Nuclear Information System (INIS)

    Stabilization of municipal solid waste (MSW) is affected by moisture, nutrients, oxygen, pH and accumulation of inhibitory fermentation products, etc. Optimization of these parameters could create a favorable environment that promotes the rapid development of the desired microbial population and acceleration of decomposition of MSW. The objectives of this work was to determine the feasibility of enhancing phase separation through intermittent aeration strategy throughout the treatment process; to demonstrate the potential of active sludge for in situ nitrogen removal; to examine the efficiency and evaluate the possibility of in situ removal of contaminants from leachate. The results indicate that the removal ratio of COD, BOD5, NH4+ and total nitrogen are over 80, 81, 75, and 74%, respectively, in the leachate recirculation reactors with aeration; the removal efficiency of NH4+ and total nitrogen of the reactor which were added active sludge were 88 and 84%, respectively. Therefore, aeration strategy has positive impacts on the solid waste stabilization; addition of active sludge in reactor is favorable for the remediation of the nitrogen; using landfill itself for in situ attenuating the contaminants from leachate is feasible

  15. Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli

    International Nuclear Information System (INIS)

    Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 J/m2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O2-radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn2+ and Fe2+, inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N2 for 90 min, the respiration, growth, and viability time-course responses were the same as for cells not exposed to anaerobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation of respiration and cell death and that inadequate aeration or anaerobiosis delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration

  16. Relationship between respiratory quotient, nitrification, and nitrous oxide emissions in a forced aerated composting process

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsui, Hirofumi, E-mail: jm-tsutsuih@kochi-u.ac.jp [Research and Education Faculty, Natural Sciences Cluster, Agriculture Unit, Kochi University, B200 Monobe, Nankoku, Kochi (Japan); Japan Science and Technology Agency, CREST (Japan); Fujiwara, Taku [Research and Education Faculty, Natural Sciences Cluster, Agriculture Unit, Kochi University, B200 Monobe, Nankoku, Kochi (Japan); Japan Science and Technology Agency, CREST (Japan); Inoue, Daisuke [Department of Health Science, School of Allied Health Sciences, Kitasato University, 1-15-1 Kitasato, Sagamihara-Minami, Kanagawa (Japan); Japan Science and Technology Agency, CREST (Japan); Ito, Ryusei [Department of Environmental Engineering, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido (Japan); Japan Science and Technology Agency, CREST (Japan); Matsukawa, Kazutsugu [Research and Education Faculty, Multidisciplinary Science Cluster, Life and Environmental Medicine Science Unit, Kochi University, B200 Monobe, Nankoku, Kochi (Japan); Japan Science and Technology Agency, CREST (Japan); Funamizu, Naoyuki [Department of Environmental Engineering, Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido (Japan); Japan Science and Technology Agency, CREST (Japan)

    2015-08-15

    Highlights: • RQ can be an indicator of N{sub 2}O emission in forced aerated composting process. • Emission of N{sub 2}O with nitrification was observed with RQ decrease. • Mass balances demonstrated the RQ decrease was caused by nitrification. • Conversion ratio of oxidized ammonia and total N to N{sub 2}O were ∼2.7%. - Abstract: We assessed the relationship between respiratory quotient (RQ) and nitrification and nitrous oxide (N{sub 2}O) emission in forced aerated composting using lab-scale reactors. Relatively high RQ values from degradation of readily degradable organics initially occurred. RQ then stabilized at slightly lower values, then decreased. Continuous emission of N{sub 2}O was observed during the RQ decrease. Correlation between nitrification and N{sub 2}O emission shows that the latter was triggered by nitrification. Mass balances demonstrated that the O{sub 2} consumption of nitrification (∼24.8 mmol) was slightly higher than that of CO{sub 2} emission (∼20.0 mmol), indicating that the RQ decrease was caused by the occurrence of nitrification. Results indicate that RQ is a useful index, which not only reflects the bioavailability of organics but also predicts the occurrence of nitrification and N{sub 2}O emission in forced aerated composting.

  17. Effects of Aeration Treatment on γ-Aminobutyric Acid Accumulation in Germinated Tartary Buckwheat (Fagopyrum tataricum

    Directory of Open Access Journals (Sweden)

    Yuanxin Guo

    2016-01-01

    Full Text Available To explore the optimum condition of γ-aminobutyric acid (GABA accumulation in germinated tartary buckwheat, effects of some factors including aeration treatment, physiological indexes, air flow rate, culture temperature, and pH value of cultivating solution under hypoxia on GABA in germinated tartary buckwheat were investigated. The results showed that the dark cultures with distilled water at 30°C, 2 days, and aeration stress with 1.0 L/min air flow rate at 30°C were optimal for GABA accumulation. Under these conditions, the predicted content of GABA was up to 371.98 μg/g DW. The analysis of correlation indicated that there was a significant correlation (P<0.01 between GABA accumulation and physiological indexes. Box-Behnken experimental analysis revealed that optimal conditions with aeration treatment for GABA accumulation in germinated tartary buckwheat were air flow rate of 1.04 L/min, culture temperature of 31.25°C, and a pH value of 4.21. Under these conditions, the GABA content was predicted as high as 386.20 μg/g DW, which was close to the measured value (379.00±9.30 μg/g DW. The variance analysis and validation test suggested that this established regression model could predict GABA accumulation in tartary buckwheat during germination.

  18. Multiple electron transfer systems in oxygen reducing biocathodes revealed by different conditions of aeration/agitation.

    Science.gov (United States)

    Rimboud, Mickaël; Bergel, Alain; Erable, Benjamin

    2016-08-01

    Oxygen reducing biocathodes were formed at -0.2V/SCE (+0.04V/SHE) from compost leachate. Depending on whether aeration was implemented or not, two different redox systems responsible for the electrocatalysis of oxygen reduction were evidenced. System I was observed at low potential (-0.03V/SHE) on cyclic voltammetries (CVs). It appeared during the early formation of the biocathode (few hours) and resisted the hydrodynamic conditions induced by the aeration. System II was observed at higher potential on CV (+0.46V/SHE); it required a longer lag time (up to 10days) and quiescent conditions to produce an electrochemical signal. The hydrodynamic effects produced by the forced aeration led to its extinction. From their different behaviors and examples in the literature, system I was identified as being a membrane-bound cytochrome-related molecule, while system II was identified as a soluble redox mediator excreted by the biofilm. This study highlighted the importance of controlling the local hydrodynamics to design efficient oxygen reducing biocathodes able to operate at high potential. PMID:27035588

  19. Modeling of mixing in stirred bioreactors 4. mixing time for aerated bacteria, yeasts and fungus broths

    Directory of Open Access Journals (Sweden)

    Cascaval Dan

    2004-01-01

    Full Text Available The mixing time for bioreactors depends mainly on the rheoiogicai properties of the broths, the biomass concentration and morphology, mixing system characteristics and fermentation conditions. For quantifying the influence of these factors on the mixing efficiency for stirred bioreactors, aerated broths of bacteria (P. shermanii, yeasts (S. cerevisiae and fungi (P. chrysogenum, free mycelia and mycelial aggregates of different concentrations have been investigated using a laboratory bioreactor with a double turbine impeller. The experimental data indicated that the influence of the rotation speed, aeration rate and stirrer positions on the mixing intensity strongly differ from one system to another and must be correlated with the microorganism characteristics, namely: the biomass concentration and morphology. Moreover, compared with non-aerated broths, variations of the mixing time with the considered parameters are very different, due to the complex flow mechanism of gas-liquid dispersions. By means of the experimental data and using a multiregression analysis method some mathematical correlations for the mixing time of the general form: tm = a1*Cx2+a2*Cx+a3*IgVa+a4-N2+a5-N+a6/a7*L2+a8*L+a9 were established. The proposed equations offer good agreement with the experiments, the average deviation being ±6.7% - ±9.4 and are adequate for the flow regime Re < 25,000.

  20. Properties of Agro-Industrial Aerated Concrete as Potential Thermal Insulation for Building

    Directory of Open Access Journals (Sweden)

    Aminudin Eeydzah

    2016-01-01

    Full Text Available The present paper is aiming to provide an actual state of the development of non autoclaved Agro-Industrial aerated concrete by using multiple ashes as improvement of thermal behavior for building. The feasibility of Agro-Industrial wastes as lightweight concrete by utilizing the Palm Oil Fuel Ash (POFA as binder replacement and bottom ash as fine aggregate was investigated in this paper. Portland cement, bottom ash, aluminum powder and lime (Ca(OH2 were used in this study. The POFA was used to replace Portland cement and Hydrated Lime at 0%, 5%, 10% and 15% by weight and aluminum powder was added at 0.75% dry weight in order to form bubbles. The compressive strength, water absorption, porosity and the thermal conductivity test were carried out after the concrete were water cured for 7 days and later being exposed to the air and water until 28days. The results show that the 20% replacements give the optimum strength of 7.143MPa and 30% give the best thermal conductivity with 0.48W/mK. Hence, this study aim, was to develop an agro-industrial aerated concrete good in insulation but having an optimum strength. Hence, it has been found that the more the percentage of POFA is added the lower the thermal conductivity since the pore structure is increasing and by the optimization done, 30% replacement has been chosen as the best mix design for Agro-Industrial Aerated Concrete.

  1. Greenhouse gas production and efficiency of planted and artificially aerated constructed wetlands

    International Nuclear Information System (INIS)

    Greenhouse gas (GHG) emissions by constructed wetlands (CWs) could mitigate the environmental benefits of nutrient removal in these man-made ecosystems. We studied the effect of 3 different macrophyte species and artificial aeration on the rates of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) production in CW mesocosms over three seasons. CW emitted 2-10 times more GHG than natural wetlands. Overall, CH4 was the most important GHG emitted in unplanted treatments. Oxygen availability through artificial aeration reduced CH4 fluxes. Plant presence also decreased CH4 fluxes but favoured CO2 production. Nitrous oxide had a minor contribution to global warming potential (GWP < 15%). The introduction of oxygen through artificial aeration combined with plant presence, particularly Typha angustifolia, had the overall best performance among the treatments tested in this study, including lowest GWP, greatest nutrient removal, and best hydraulic properties. - Methane is the main greenhouse gas produced in constructed wetlands and oxygen availability is the main factor controlling fluxes

  2. Use of floating balls for reducing bacterial aerosol emissions from aeration in wastewater treatment processes.

    Science.gov (United States)

    Hung, Hsueh Fen; Kuo, Yu Mei; Chien, Chih Ching; Chen, Chih Chieh

    2010-03-15

    The microorganism emissions from aeration in the wastewater treatment process may adversely affect air quality and human health. To control the liquid-to-air transport of microorganisms, commercially available balls were used and their control efficiencies were evaluated by a lab-scale aeration system. Escherichia coli as the test agent were aerosolized by the aeration system and size-fractionated E. coli-containing aerosol samples were collected by using an Andersen six-stage impactor with eosin methylene blue agar for subsequent culturing and enumeration of colonies. Aerosol samples were obtained without any control measure and with balls of four diameters (1.9, 2.9, 3.4 and 4.8 cm) in one, three and five layers covering the bubbling liquid surface. Experimental results showed that the control efficiencies of balls on bacterial aerosols varied from over 50% to nearly 100% under various control settings and substantially increased as the ball size decreased and the number of applied layers increased. PMID:19939557

  3. Removal of nitrogen from MBT residues by leachate recirculation in combination with intermittent aeration.

    Science.gov (United States)

    Tran, Hoai Nam; Münnich, Kai; Fricke, Klaus; Harborth, Peter

    2014-01-01

    Mechanical-biological treatment (MBT) techniques have been used to reduce the emission potential of waste before placement in landfills for a couple of years, especially in Europe. The main focus of MBT is on the reduction of native organic substances and not on nitrogen compounds. As a result, the concentrations of organic substances in leachate from MBT landfills are considerably reduced in comparison to leachates from municipal solid waste landfills, while the ammonia nitrogen concentrations remain at a high level. From the stabilization of old landfills it is well known that recirculation of leachate and supplementary aeration can reduce emissions to an acceptable level in a comparatively short time. In a series of laboratory-scale tests the efficiency of this technique for MBT residues was investigated under different boundary conditions. While the effect of leachate recirculation is also well known for MBT residues, the additional aeration has so far not been investigated. The results show that this technique has only a limited influence on the reduction of organic carbon compounds. In view of nitrogen compounds, only the additional aeration during recirculation shows a strong effect on the quality of leachate, in which the concentrations of ammonium and total nitrogen are reduced by more than 90%. The results indicate that by using simple techniques the long-term emission behavior of MBT residues can be quickly reduced to an acceptable level. PMID:24293068

  4. Performance of simultaneous nitrification and denitrification in lateral flow biological aerated filter

    Institute of Scientific and Technical Information of China (English)

    LONG Teng-rui; CAO Yan-xiao; ZHANG Hong-jing; GAO Xiao-tao

    2006-01-01

    A new wastewater treatment facility-lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has the function of nitrification and removing organic substrate. In this study, we focused on the denitrification performance of LBAF and its possible mechanism under thorough aeration. We identified the existence of simultaneous nitrification and denitrification (SND)by analyzing nitrogenous compounds along the flow path of LBAF and supportive microbial microscopy, and studied the effects of air/water ratio and hydraulic loading on the performance of nitrogen removal and on SND in LBAF to find out the optimal operation condition. It is found that for saving operation cost, aeration can be reduced to some degree that allows desirable removal efficiency of pollutants, and the optimal air/water ratio is 10:1. Hydraulic loading less than 0.43 m h-1 hardly affects the nitrification and denitrification performance; whereas higher hydraulic loading is unfavorable to both nitrification and denitrification, far more unfavorable to denitrification than to nitrification.

  5. Relationship between respiratory quotient, nitrification, and nitrous oxide emissions in a forced aerated composting process

    International Nuclear Information System (INIS)

    Highlights: • RQ can be an indicator of N2O emission in forced aerated composting process. • Emission of N2O with nitrification was observed with RQ decrease. • Mass balances demonstrated the RQ decrease was caused by nitrification. • Conversion ratio of oxidized ammonia and total N to N2O were ∼2.7%. - Abstract: We assessed the relationship between respiratory quotient (RQ) and nitrification and nitrous oxide (N2O) emission in forced aerated composting using lab-scale reactors. Relatively high RQ values from degradation of readily degradable organics initially occurred. RQ then stabilized at slightly lower values, then decreased. Continuous emission of N2O was observed during the RQ decrease. Correlation between nitrification and N2O emission shows that the latter was triggered by nitrification. Mass balances demonstrated that the O2 consumption of nitrification (∼24.8 mmol) was slightly higher than that of CO2 emission (∼20.0 mmol), indicating that the RQ decrease was caused by the occurrence of nitrification. Results indicate that RQ is a useful index, which not only reflects the bioavailability of organics but also predicts the occurrence of nitrification and N2O emission in forced aerated composting

  6. Nitrogen removal performance of intermittently aerated membrane bioreactor treating black water.

    Science.gov (United States)

    Hocaoglu, S Murat; Atasoy, E; Baban, A; Insel, G; Orhon, D

    2013-01-01

    The study investigated the effect of intermittent aeration on the nitrogen removal performance of a membrane bioreactor (MBR) treating black water. A pilot-scale MBR with an effective volume of 630 L operating as a sequencing batch reactor (SBR) with intermittent aeration was used in the experiments. Substrate feeding was limited to the initial non-aerated phase. The MBR unit was sustained at a steady state at a sludge age of 60 d with a biomass concentration of around 10,000 mg/L for 3 months. The treated black water could be characterized with an average COD of 950 mg/L and total nitrogen of 172 mg/L, corresponding to a low COD/N ratio of 5.5. The selected MBR scheme was quite effective, reducing COD down to 26 mg/L, providing effective nitrification and yielding a total oxidized nitrogen concentration under 10 mg N/L. The nitrogen removal performance was substantially better than the level predicted by process stoichiometry, due to multiple anoxic configuration inducing additional nitrogen removal. Dissolved oxygen profiles associated with the cyclic operation of the system suggested that the incremental nitrogen removal could be attributed to simultaneous nitrification-denitrification, a commonly observed mechanism in MBR systems sustained at high biomass concentrations. PMID:24527634

  7. Biogas production enhancement using semi-aerobic pre-aeration in a hybrid bioreactor landfill.

    Science.gov (United States)

    Cossu, Raffaello; Morello, Luca; Raga, Roberto; Cerminara, Giulia

    2016-09-01

    Landfilling continues to be one of the main methods used in managing Municipal Solid Waste (MSW) worldwide, particularly in developing countries. Although in many countries national legislation aims to reduce this practice as much as possible, landfill is a necessary and unavoidable step in closing the material cycle. The need for innovative waste management techniques to improve landfill management and minimize the adverse environmental impact produced has resulted in an increasing interest in innovative systems capable of accelerating waste stabilization. Landfill bioreactors allow decomposition kinetics to be increased and post-operational phase to be shortened; in particular, hybrid bioreactors combine the benefits afforded by both aerobic and anaerobic processes. Six bioreactor simulators were used in the present study: four managed as hybrid, with an initial semi-aerobic phase and a second anaerobic phase, and two as anaerobic control bioreactors. The main goal of the first aerated phase is to reduce Volatile Fatty Acids (VFA) in order to increase pH and enhance methane production during the anaerobic phase; for this reason, air injection was stopped only when these parameters reached the optimum range for methanogenic bacteria. Biogas and leachate were constantly monitored throughout the entire methanogenic phase with the aim of calibrating a Gompertz Model and evaluating the effects of pre-aeration on subsequent methane production. The results showed that moderate and intermittent pre-aeration produces a positive effect both on methane potential and in the kinetics of reaction. PMID:26531047

  8. Aerator Selection in Pulping & Papermaking Wastewater Treatment Engineering%造纸废水处理工程曝气器优选

    Institute of Scientific and Technical Information of China (English)

    王少艮; 张会敏

    2013-01-01

    The characteristics and application scopes of existing aeration equipment used in pulping and papermaking wastewater treatment, such as blasting aerator, jet aerator and mechanical aerator were summarized in this paper. To avoid the disadvantage of the existing aeration system, an innovational rotational flow aerator was introduced, and its advantage and engineering examples were discussed.%讨论了现有曝气设备,包括鼓风曝气、射流曝气和机械曝气设备的特点及适用范围,针对现有曝气器在造纸废水应用中的不足,系统介绍了新型高效旋流曝气器的特征及其在造纸废水处理中的应用优势和工程实例.

  9. Coupling of bio-PRB and enclosed in-well aeration system for remediation of nitrobenzene and aniline in groundwater.

    Science.gov (United States)

    Liu, Na; Ding, Feng; Wang, Liu; Liu, Peng; Yu, Xiaolong; Ye, Kang

    2016-05-01

    A laboratory-scale bio-permeable reactive barrier (bio-PRB) was constructed and combined with enclosed in-well aeration system to treat nitrobenzene (NB) and aniline (AN) in groundwater. Batch-style experiments were first conducted to evaluate the effectiveness of NB and AN degradation, using suspension (free cells) of degrading consortium and immobilized consortium by a mixture of perlite and peat. The NB and AN were completely degraded in aeration system was assessed in a box filled with perlite and peat. Dissolved O2 (DO) concentrations increased to 8-12 mg L(-1) in 12 h for sampling ports within 12 cm of the aeration well. A diffusion coefficient as 33.5 cm(2) s(-1) was obtained. The DO concentration was >4 mg L(-1) when the aeration system was applied into the bio-PRB system. The NB and AN were effectively removed when the aeration system was functional in the bio-PRB. The removal efficiency decreased when the aeration system malfunctioned for 20 days, thus indicating that DO was an important factor for the degradation of NB and AN. The regain of NB and AN removal after the malfunction indicates the robustness of degradation consortium. No original organics and new formed by-products were observed in the effluent. The results indicate that NB and AN in groundwater can be completely mineralized in a bio-PRB equipped with enclosed in-well aeration system and filled with perlite and peat attached with degrading consortium. PMID:26865481

  10. Changes in the chemical and physicochemical properties of the solid fraction of cattle slurry during composting using different aeration strategies.

    Science.gov (United States)

    Cáceres, Rafaela; Flotats, Xavier; Marfà, Oriol

    2006-01-01

    Replacement of peat as a growing medium by a renewable material, such as an organic waste, is an issue of concern since harvesting of peat has a considerable environmental impact and, actually, it is a non-renewable resource. Cattle manure is a readily available organic waste, which means that once it goes through the composting process, it can be used as an alternative to peat, specifically, the solid fraction obtained from mechanical liquid-solid separation of cattle slurry (SF). Studies have shown it to be suitable for such uses. The purpose of this study was to detect possible changes in the physicochemical and chemical properties of SF when it is composted using different aeration strategies, with an emphasis on the changes that would make it feasible for use as a substrate. With this aim in mind, an experiment was designed with three aeration strategies that would be used during composting. The first consisted of applying air through a static method (forced ventilation). The second involved improving aeration by adding a bulking agent and a dynamic turning method. In the third strategy, aeration was carried out by turning (control). The results show that the different aeration strategies had a clear effect on the evolution of pH, electrical conductivity (EC), nitrate-N, ammonia-N and bicarbonate content. Nitrification was favored under good aeration conditions using the static composting method, probably due to the greater availability of ammonia-N that was transformed into nitrate-N. In general, the low buffering capacity allowed for a reduction of the pH during the curing stage of composting (in conjunction with low temperatures during this period), a characteristic that favors the use of this compost as a growing medium. We also conclude that measuring bicarbonate levels during composting could be used as an indicator of the possible acidification of the material and as a way of evaluating the level of material aeration. PMID:16146687

  11. Removal of radon by aeration testing of various aeration techniques for small water works. For European Commission under Contract No FI4PCT960054 TENAWA project

    CERN Document Server

    Salonen, L; Mehtonen, J; Mjoenes, L; Raff, O; Turunen, H

    2002-01-01

    Capability of various aeration techniques to remove radon from water in small waterworks was studied as a part of project (Treatment Techniques for Removing Natural Radionuclides from Drinking Water), which was carried out during 1997-1999 on a cost-shared basis (contract No. F14PCT960054) with The European Commission (CEC) under the supervision of the Directorate-General XII Radiation Protection Research Unit. In TENAWA project both laboratory and field experiments were performed in order to find reliable methods and equipment for removing natural radionuclides from ground water originating either from private wells or small waterworks. Because such techniques are more often needed in private households than at waterworks, the main emphasis of the research was aimed to solve the water treatment problems related to the private water supplies, especially bedrock wells. Radon was the most important radionuclide to be removed from water at waterworks whereas the removal of other radionuclides ( sup 2 sup 3 sup 4...

  12. Immunotoxic potential of aeration lagoon effluents for the treatment of domestic and hospital wastewaters in the freshwater mussel Elliptio complanata.

    Science.gov (United States)

    Gagné, Francois; André, Chantale; Fortier, Marlène; Fournier, Michel

    2012-01-01

    Municipal wastewaters are major sources of pollution for the aquatic biota. The purpose of this study was to determine the levels of some pharmaceutical products and the immunotoxic potential of a municipal wastewater aeration lagoon for the treatment of the domestic wastewaters of a small town with wastewater inputs from a 400-bed hospital complex. Endemic mussels were collected, caged and placed in the final aeration lagoon and at sites 1 km upstream and 1 km downstream of the effluent outfall in the receiving river for a period of 14 days. The results showed that the final aeration lagoon contained high levels of total coliforms, conductivity and low dissolved oxygen (2.9 mg/L) as well as detectable amounts of trimethoprim, carbamazepine, gemfibrozil, and norfloxacin at concentrations exceeding 50 ng/L. The lagoon effluent was indeed toxic to the mussel specimens, as evidenced by the appearance of mortality after 14 days (10% mortality), decreased mussel weight-to-shell-length ratio and loss of hemocyte viability. The number of adhering hemocytes, phagocytic activity, total nitrite levels and arachidonic cyclooxygenase activity were significantly higher in mussels placed in the final aeration lagoon. A multivariate analysis also revealed that water pH, conductivity, total coliforms and dissolved oxygen were the endpoints most closely linked with phagocytic activity, the amount of adhering hemocytes and loss of hemocyte viability. In conclusion, exposure of mussels to treated aerated lagoon wastewater is deleterious to freshwater mussels where the immune system is compromised. PMID:22893952

  13. Changes in the soil moisture regime in the aeration zone after setting the Gabcikovo hydroelectric power structures into operation

    International Nuclear Information System (INIS)

    Setting the hydroelectric power structures Gabcikovo into operation impacts the regime of surface and ground water. Changes in the ground water regime are transferred to the biosphere through the aeration zone. These changes are manifested in the changes of soil moisture regime in the aeration zone. It may be stated that if there is an increase of the ground water level due to construction of hydroelectric power structures, then there is also an increase in humidity in the aeration zone, while it may occasionally remain unchanged at some locations, in no case does it decrease. The same is valid also reciprocally. If there is a drop of ground water level due to hydroelectric power structures, then there is also a decrease of moisture in the aeration zone, occasionally it may be unchanged at some locations, but in no case does it increase. Therefore, neither increase of moisture due to the decrease of ground water level, nor the opposite can happen. Changes in the soil moisture in the aeration zone for selected localities along the Danube are charted on the graphs for the interval of years 1990-1994. For the comparison the fluctuation of the ground water, the date of damming the Danube and the date of the start of river branches water supply, etc., are given. (authors). 1 tabs., 17 figs., 10 maps, 10 refs

  14. Dose distribution resulting from changes in aeration of nasal cavity or paranasal sinus cancer in the proton therapy

    International Nuclear Information System (INIS)

    Background and purpose: Aeration in the nasal cavity and paranasal sinus (NCPS) was investigated during the course of proton therapy (PT), and the influence of aeration on the dose distribution was determined. Material and methods: Twenty patients with NCPS cancer (10 nasal cavity, 10 paranasal sinus) were analyzed. All the patients received a total proton beam irradiation dose of 38–78.4 Gray equivalents (GyE). Two to five CT examinations were performed during the course of treatment. The aeration ratio inside the cavity/sinus was calculated for each CT observation. Moreover, a simulation study supposing that the first treatment plan had been continued until the end of treatment was performed using the subsequent CT findings. Results: The aeration ratio was increased in 18 patients. The largest increase was from 15% to 82%. Three patients had a simulated maximum cumulative dose in the brainstem of beyond 60 GyE, while 10 patients had a simulated maximum cumulative dose in the optic chiasm of beyond 50 GyE. The shortest simulated time period to reach the dose limitation was 21 days. Conclusions: Aeration in the NCPS is altered during the course of PT treatment and can greatly alter the dose distribution in the brainstem and optic chiasm

  15. The effect of aeration and recirculation on a sand-based hybrid constructed wetland treating low-strength domestic wastewater.

    Science.gov (United States)

    Zapater-Pereyra, M; Kyomukama, E; Namakula, V; van Bruggen, J J A; Lens, P N L

    2016-08-01

    The Duplex-constructed wetland (CW) is a hybrid system composed of a vertical flow (VF) CW on top of a horizontal flow filter (HFF). Each compartment is designed to play a different role: aerobic treatment in the VF CW due to intermittent feeding and anoxic treatment in the HFF due to saturated conditions. Three Duplex-CWs were used in this study: Control, Aerated and Recirculating. The role of each compartment was tested for pollutant removal and micro-invertebrate abundance. In all systems, the VF CW removed mainly organic matter, solids and NH4(+)-N. Pathogens were removed in both compartments. Likewise, total nitrogen removal occurred in both compartments, only the Recirculating HFF was not able to denitrify the nitrogen due to the slightly more oxic conditions as compared to the other systems. All systems met discharge guidelines for organic matter, but only the Control and Aerated systems met those for total nitrogen. At the applied loading rates, the pollutant removal was not significantly enhanced by the use of aeration and recirculation. Therefore, operation as in the Control system, without aeration or recirculation, is recommended for the tested Duplex-CWs. If artificial aeration will be used in CWs, the support material should be carefully selected to allow a proper air distribution. PMID:26732367

  16. Liquid and atmospheric ammonia concentrations from a dairy lagoon during an aeration experiment

    Science.gov (United States)

    Rumburg, Brian; Neger, Manjit; Mount, George H.; Yonge, David; Filipy, Jenny; Swain, John; Kincaid, Ron; Johnson, Kristen

    Ammonia emissions from agriculture are an environmental and human health concern, and there is increasing pressure to reduce emissions. Animal agriculture is the largest global source of ammonia emissions and on a per cow basis dairy operations are the largest emitters. The storage and disposal of the dairy waste is one area where emissions can be reduced, aerobic biological treatment of wastewater being a common and effective way of reducing ammonia emissions. An aeration experiment in a dairy lagoon with two commercial aerators was performed for 1 month. Liquid concentrations of ammonia, total nitrogen, nitrite and nitrate were monitored before, during and after the experiment and atmospheric ammonia was measured downwind of the lagoon using a short-path differential optical absorption spectroscopy (DOAS) instrument with 1 ppbv sensitivity. No changes in either liquid or atmospheric ammonia concentrations were detected throughout the experiment, and neither dissolved oxygen, nitrite nor nitrate could be detected in the lagoon at any time. The average ammonia concentration at 10 sampling sites in the lagoon at a depth of 0.15 m was 650 mg l -1 and at 0.90 m it was 700 mg l -1 NH 3-N. The average atmospheric ammonia concentration 50 m downwind was about 300 ppbv. The 0.90 m depth total nitrogen concentrations and total and volatile solids concentrations decreased during the experiment due to some mixing of the lagoon but the 0.15 m depth concentrations did not decrease indicating that the aerators were not strong enough to mix the sludge off the bottom into the whole water column.

  17. Laboratory model of radionuclide migration in the aeration zone of country between Uzh and Pripyat' rivers

    International Nuclear Information System (INIS)

    Special installation for modelling of the radionuclide migration in the aeration zone was presented to predict the ground water state in the Chernobyl' accident region. This installation was under operation in the Chernobyl' radiochemical laboratory from 1987, September. Results of the first stage of experiment have shown that the level of total beta-activity of recharge run-off samples is 10-9 Ci/l, while the total beta-activity of model 'ground water' is half an order less in average. Cs-137, Cs-134, Ce-144, Ru-106 radionuclides were found in run-off samples. 7 figs

  18. Effects of toxicity, aeration, and reductant supply on trichloroethylene transformation by a mixed methanotrophic culture.

    OpenAIRE

    Alvarez-Cohen, L; McCarty, P L

    1991-01-01

    The trichloroethylene (TCE) transformation rate and capacity of a mixed methanotrophic culture at room temperature were measured to determine the effects of time without methane (resting), use of an alternative energy source (formate), aeration, and toxicity of TCE and its transformation products. The initial specific TCE transformation rate of resting cells was 0.6 mg of TCE per mg of cells per day, and they had a finite TCE transformation capacity of 0.036 mg of TCE per mg of cells. Formate...

  19. Determination of re-aeration coefficients on high mountain rivers using nuclear techniques

    International Nuclear Information System (INIS)

    The rivers Machangara and Guayllabamba in Quito, Ecuador, currently are highly polluted, mainly due to human and industrial residues from the city. The objective of this survey is to establish the dynamics of dissolved oxygen in these rivers using the Krypton 85 method to determine the re aeration coefficient in representative sectors of the rivers. In addition, conventional test tracers establish mean flow speed and flow longitudinal dispersion coefficients. The results of this study will be useful for future water quality modelling of these rivers, in order to define their behaviour and auto depurative capacity to treat sludge waters from Quito

  20. STRESS CORROSION CRACKING OF NICKEL BASE SUPERALLOYS IN AERATED SUPERCRITICAL WATER

    OpenAIRE

    Fournier, L.; Delafosse, David; Bosch, C.; Magnin, Thierry

    2001-01-01

    The stress corrosion cracking behaviour of two nickel base superalloys (A718 and A690) is investigated in aerated supercritical water by means of constant extension rate tensile (CERT) tests at 400°C and 25 MPa. Alloy 718 is observed to be extremely sensitive to intergranular stress corrosion cracking (IGSCC) while alloy 690 is found to be immune to IGSCC. CERT tests are also carried out in air and under vacuum on both alloys at 600°C, i.e. in a temperature domain where nickel base superalloy...

  1. Aeration conditions modify the immobilization of Se (selenite) and Tc (pertechnetate) on various soils

    International Nuclear Information System (INIS)

    Full text: Isotopes of both selenium and technetium are important components of radioactive waste destined for long-term storage and so it is important to understand their behaviour in the environment. In addition, selenium is an essential micro-nutrient, deficient in some soils but potentially toxic at only slightly larger concentrations found naturally or as a result of human activity. Both elements are redox sensitive, having oxidation states from +7 to 0 for Tc and from +6 to -2 for Se. They are often considered to behave very similarly in the environment, with the oxy-anions dominating in well-aerated soils. We have studied the sorption of both elements in contrasting soils and compared the consequences of prolonged incubation under well-aerated, water-saturated, or strictly anaerobic conditions. We used sequential or parallel chemical extractions to assess the chemical nature of the immobilized fractions. Pertechnetate remained easily water-extractable throughout prolonged incubation of the soils under aerated conditions. However flooded, hence reducing conditions decreased the water-extractability of Tc. There was no difference between the fraction extracted by water or by simple salt solution (exchangeable fraction). However, as Tc became progressively immobilized, 1M NaOH (to solubilize humic substances) or H2O2 (to solubilize soil organic matter and reoxidize reduced forms of Tc) increased more Tc, indicating the strong association of Tc with organic matter and differing extents of chemical reduction. Selenite sorbed to differing extents on the various soils studied however the fraction extracted by water was systematically very low. There was a large difference between the water-extractable and the exchangeable fractions. Incubation of the soils under well aerated conditions led to different changes in Se extractability. Freshly added Se was more easily extracted than native Se. Addition of fresh organic matter or strictly anaerobic conditions enhanced

  2. Increased aeration for improved large-scale composting of low-pH biowaste

    OpenAIRE

    Sundberg, Cecilia

    2005-01-01

    Biowaste composting at several plants in Scandinavia has been troubled by low pH in the collected waste as well as after the composting process. Our hypothesis was that increased aeration would give a higher and faster rise in pH during the composting process, and that this would give a higher decomposition rate. The objective was to test this hypothesis by experiments in full scale, with an emphasis on the role of temperature in the transition from acidic to neutral pH. Experiments were carr...

  3. Fate of microconstituents in biosolids composted in an aerated silage bag.

    Science.gov (United States)

    Lozano, Nuria; Andrade, Natasha A; Deng, Di; Torrents, Alba; Rice, Clifford P; McConnell, Laura L; Ramirez, Mark; Millner, Patricia D

    2014-01-01

    Although most composting studies report pathogen concentrations, little is known about the fate of Endocrine Disruptor Chemicals (EDCs) during composting. In this study, a positively aerated polyethylene bag composting system was filled with a mixture of woodchips and limed biosolids from a large Waste Water Treatment Plant (WWTP) to study the removal efficiency of two different groups of EDCs. Two antibacterial compounds, Triclocarban (TCC) and Triclosan (TCS), and a TCS byproduct, Methyltriclosan (MeTCS), as well as seven congeners of flame retardants known as PBDEs (Polybrominated Diphenyl Ethers) were studied during two phases of composting: 1) a thermophilic phase, in which positive mechanical aeration, pushing air into and through the materials matrix, was conducted for 2 months; and 2) a curing and stabilization phase in which no mechanical aeration was provided and the bag was opened to ambient passive aeration to simulate storage conditions for seven months. Our results showed that while TCC concentrations remained constant, TCS degradation took place during both phases. The degradation of TCS was corroborated by the formation of MeTCS in both phases. The TCS concentrations decreased from 18409 ± 1,877 to 11955 ± 288 ng g(-1) dry wt. during the thermophilic phase and declined from 11,955 ± 288 to 7,244 ± 909. ng g(-1) dry wt. by the end of the curing phase. Thus, slightly greater TCS transformation occurred during the second than during the first (35.1 vs. 39.4%). MeTCS concentrations increased from 189.3 ± 8.6 to 364.6 ± 72.5 ng g(-1) dry wt. during the first phase and reached 589.0 ± 94.9 ng g(-1) dry wt. at the end of the second phase. PBDEs concentrations were below quantification limits for all but two of the congeners analyzed (BDE-47 and BDE-99). PBDE concentrations were measured at the end of the first phase only and were comparable to initial concentrations. PMID:24521417

  4. Enhanced Nutrient Removal with Upflow Biological Aerated Filter for Reclaimed Water

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-dong; PENG Yong-zhen; WANG Shu-ying; ZHANG Yan-ping

    2007-01-01

    A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2mg/L, and total phosphorus of 0.3mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrification.

  5. Properties of Agro-Industrial Aerated Concrete as Potential Thermal Insulation for Building

    OpenAIRE

    Aminudin Eeydzah; Md Din Mohd Fadhil; Hussin Mohd Warid; Abdullah Abd Halid; Iwao Kenzo; Ichikawa Yo

    2016-01-01

    The present paper is aiming to provide an actual state of the development of non autoclaved Agro-Industrial aerated concrete by using multiple ashes as improvement of thermal behavior for building. The feasibility of Agro-Industrial wastes as lightweight concrete by utilizing the Palm Oil Fuel Ash (POFA) as binder replacement and bottom ash as fine aggregate was investigated in this paper. Portland cement, bottom ash, aluminum powder and lime (Ca(OH)2) were used in this study. The POFA was us...

  6. The effects of micro-aeration on the phylogenetic diversity of microorganisms in a thermophilic anaerobic municipal solid-waste digester.

    Science.gov (United States)

    Tang, Yueqin; Shigematsu, Toru; Ikbal; Morimura, Shigeru; Kida, Kenji

    2004-05-01

    We demonstrated previously that micro-aeration allows construction of an effective thermophilic methane-fermentation system for treatment of municipal solid waste (MSW) without production of H(2)S. In the present study, we compared the microbial communities in a thermophilic MSW digester without aeration and with micro-aeration by fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), phylogenetic analysis of libraries of 16S rRNA gene clones and quantitative real-time PCR. Moreover, we studied the activity of sulfate-reducing bacteria (SRB) by analysis of the transcription of the gene for dissimilatory sulfite reductase (dsr). Experiments using FISH revealed that microorganisms belonging to the domain Bacteria dominated in the digester both without aeration and with micro-aeration. Phylogenetic analysis based on 16S rRNA gene and analysis of bacteria by DGGE did not reveal any obvious difference within the microbial communities under the two aeration conditions, and bacteria affiliated with the phylum Firmicutes were dominant. In Archaea, the population of Methanosarcina decreased while the population of Methanoculleus increased as a result of micro-aerations as revealed by the analysis of 16S rRNA gene clones and quantitative real-time PCR. Reverse transcription and PCR (RT-PCR) demonstrated the transcription of dsrA not only in the absence of aeration but also in the presence of micro-aeration, even under conditions where no H(2)S was detected in the biogas. In conclusion, micro-aeration has no obvious effects on the phylogenetic diversity of microorganisms. Furthermore, the activity of SRBs in the digester was not repressed even though the concentration of H(2)S in the biogas was very low under the micro-aeration conditions. PMID:15159157

  7. Oxygen Mass Transfer in an Aerated Stirred Tank with Double Impellers: A Generalized Correlation Including Spacing Impact

    Directory of Open Access Journals (Sweden)

    Hayder Mohammed Issa

    2016-01-01

    Full Text Available Stirred aerated tanks by double impellers are used in fermentation and various biological processes for water treatment, food industry, and pharmaceutical production. In this study, a generalized correlation model was developed for the dependent parameter (kla/N. The oxygen mass transfer from air to liquid takes place by rotating the double impellers (IBRC and PBPU in the aerated tank. This model considers Reynolds number, Froude number, power number, the liquid height, and the spacing between impellers as the most significant specifications that are related to aerated tank performance. The spacing between the impellers is considered to be a design factor of such industrial equipment due to its remarkable impact on the oxygen mass transfer.

  8. Microfaunal indicators, Ciliophora phylogeny and protozoan population shifts in an intermittently aerated and fed bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Ntougias, Spyridon, E-mail: sntougia@env.duth.gr [Democritus University of Thrace, Department of Environmental Engineering, Laboratory of Wastewater Management and Treatment Technologies, Vas. Sofias 12, 67100 Xanthi (Greece); Tanasidis, Spartakos; Melidis, Paraschos [Democritus University of Thrace, Department of Environmental Engineering, Laboratory of Wastewater Management and Treatment Technologies, Vas. Sofias 12, 67100 Xanthi (Greece)

    2011-02-28

    Microfauna community structure was examined in the mixed liquor of a bench-scale bioreactor equipped with an intermittent aeration and feeding system. The reactor was operated under an intermittent aeration of 25 min in every 1 h and varying feeding conditions (0.264, 0.403 and 0.773 kg BOD{sub 5}/m{sup 3} d). A total of 14 protozoan and metazoan taxa were identified by microscopic examination. Sessile ciliates, followed by crawling ciliates, were the major protozoan groups under 0.403 kg BOD{sub 5}/m{sup 3} d organic loading conditions, while sessile ciliate population was remarkably increased under an organic loading of 0.773 kg BOD{sub 5}/m{sup 3} d. Principal Component Analysis and Pearson correlation coefficient tests were performed in order to reveal relationships between microfauna community and operational parameters. Ciliophora specific-18S rRNA gene clone library was constructed to identify ciliate diversity under 0.773 kg BOD{sub 5}/m{sup 3} d organic loading conditions. Ciliophora diversity consisted of members of Aspidiscidae, Epistylidae, Opisthonectidae and Vorticellidae, with the majority of the clones being associated with the species Vorticella fusca. At least one novel phylogenetic linkage among Ciliophora was identified. Comparisons made after molecular characterization and microscopic examination of Ciliophora community showed that the estimation of broad ciliate groups is useful for ecological considerations and evaluation of the operational conditions in wastewater treatment plants.

  9. The Efficiency of Iron and Manganese Removal from Groundwater Using Tower Aeration

    Directory of Open Access Journals (Sweden)

    Meghdad Pirsaheb

    2012-09-01

    Full Text Available Groundwaters passing through different layers of soil and due to its water properties and its high solubility, contain elements and minerals of material in the soil that sometimes can be dangerous for the health of consumers or at least undesirable in terms of cognitive beautiful. Iron and manganese are from constitutive of the soil and rocks of the Earth's surface. Water penetration through soil and rock can minerals such as these elements have dissolved and bring them into solution. The problems of iron and manganese in groundwater in domestic installations, commercial, industrial and refineries are created, and because much of the community water supply from underground water supplies will be removed where iron and manganese concentrations exceeded it is necessary. In this study Tower aeration system performance for the removal of iron and manganese from groundwater sources have been studied. In this research, pilot column aeration tower design, implementation and was established. This system made of PVC with a diameter and height 150 cm and 15 cm which was filled with flexible pipe parts. The initial pH=5, 7 and 9 and the initial concentration of Fe and Mn 2, 3 and 4 mg/l of the output system, sampling was done.

  10. Treatment of Alkaline Stripped Effluent in Aerated Constructed Wetlands: Feasibility Evaluation and Performance Enhancement

    Directory of Open Access Journals (Sweden)

    Keli He

    2016-09-01

    Full Text Available Ammonium stripping has gained increasing interest for nitrogen recovery in anaerobically digested effluents. However, the stripped effluents often still do not meet discharge standards, having high pH and residual pollutants. Constructed wetlands (CWs are an easy to operate ecosystem and have a long history of application in treatment of wastewaters with extreme pH, such as acid mine drainage. However, knowledge of the mechanistic details involved in the use of CWs to treat high alkaline drainage, such as stripped effluent, is insufficient. This study explored the feasibility and effectiveness of using three sub-surface horizontal flow CWs to treat high alkaline stripped effluent (pH > 10. Two intensification strategies—intermittent aeration and effluent recirculation—were evaluated to enhance nitrogen depuration performance. The results show that the treatment of alkaline stripped effluent is feasible due to the high buffering capacity of the wetlands. Effluent recirculation combined with intermittent artificial aeration improves nitrogen removal, with 71% total nitrogen (TN removal. Ammonia volatilization from the surface of the wetlands in high alkaline conditions only contributed to 3% of the total removed ammonium. The microbial abundance and activity had significant diversity for the various enhancement strategies used in the constructed wetland systems. Anammox is an important process for nitrogen removal in CWs treating alkaline stripped effluent, and possible enhancements of this process should be investigated further.

  11. Effect of auxotrophies on yeast performance in aerated fed-batch reactor

    Energy Technology Data Exchange (ETDEWEB)

    Landi, Carmine; Paciello, Lucia [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy); Alteriis, Elisabetta de [Dept. Biologia Strutturale e Funzionale, Universita degli Studi di Napoli ' Federico II' , Via Cinthia, 80100 Napoli (Italy); Brambilla, Luca [Dept. Biotecnologie e Bioscienze, Universita Milano-Bicocca, Piazza della Scienza, 20126 Milano (Italy); Parascandola, Palma, E-mail: pparascandola@unisa.it [Dept. Ingegneria Industriale, Universita di Salerno, Via Ponte Don Melillo, 84084 Fisciano, Salerno (Italy)

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer The paper contributes to fill the gap existing between the basic and applied research. Black-Right-Pointing-Pointer Mathematical model sheds light on the physiology of auxotrophic yeast strains. Black-Right-Pointing-Pointer Yeast behavior in fed-batch is influenced by biological and environmental determinants. Black-Right-Pointing-Pointer Process optimization would make possible the production of heterologous proteins which are not yet on the market. -- Abstract: A systematic investigation on the effects of auxotrophies on the performance of yeast in aerated fed-batch reactor was carried out. Six isogenic strains from the CEN.PK family of Saccharomyces cerevisiae, one prototroph and five auxotrophs, were grown in aerated fed-batch reactor using the same operative conditions and a proper nutritional supplementation. The performance of the strains, in terms of final biomass decreased with increasing the number of auxotrophies. Auxotrophy for leucine exerted a profound negative effect on the performance of the strains. Accumulation of reactive oxygen species (ROS) in the cells of the strain carrying four auxotrophies and its significant viability loss, were indicative of an oxidative stress response induced by exposure of cells to the environmental conditions. The mathematical model was fundamental to highlight how the carbon flux, depending on the number and type of auxotrophies, was diverted towards the production of increasingly large quantities of energy for maintenance.

  12. Effect of auxotrophies on yeast performance in aerated fed-batch reactor

    International Nuclear Information System (INIS)

    Highlights: ► The paper contributes to fill the gap existing between the basic and applied research. ► Mathematical model sheds light on the physiology of auxotrophic yeast strains. ► Yeast behavior in fed-batch is influenced by biological and environmental determinants. ► Process optimization would make possible the production of heterologous proteins which are not yet on the market. -- Abstract: A systematic investigation on the effects of auxotrophies on the performance of yeast in aerated fed-batch reactor was carried out. Six isogenic strains from the CEN.PK family of Saccharomyces cerevisiae, one prototroph and five auxotrophs, were grown in aerated fed-batch reactor using the same operative conditions and a proper nutritional supplementation. The performance of the strains, in terms of final biomass decreased with increasing the number of auxotrophies. Auxotrophy for leucine exerted a profound negative effect on the performance of the strains. Accumulation of reactive oxygen species (ROS) in the cells of the strain carrying four auxotrophies and its significant viability loss, were indicative of an oxidative stress response induced by exposure of cells to the environmental conditions. The mathematical model was fundamental to highlight how the carbon flux, depending on the number and type of auxotrophies, was diverted towards the production of increasingly large quantities of energy for maintenance.

  13. Preparation of New Cementitious System using Fly Ash and Dehydrated Autoclaved Aerated Concrete

    Institute of Scientific and Technical Information of China (English)

    SHUI Zhonghe; LU Jianxin; TIAN Sufang; SHEN Peiliang; DING Sha

    2014-01-01

    We experimentally studied the interaction between pozzolanic material (fly ash) and dehydrated autoclaved aerated concrete (DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles finer than 75μm and was then heated to temperatures up to 900℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction (XRD) was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content (Wn). The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700℃and the dehydrated products are mainlyβ-C2S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fly ash, increasing the replacement level of fly ash lowered them in AF. The strength contribution rates on pozzolanic effect of fly ash in AF are always negative, showing a contrary tendency of that of cement-fly ash system.

  14. Synergistic aeration biosorption of uranium-containing wastewater by Banyan leaves-activated sludge

    International Nuclear Information System (INIS)

    To enhance the efficiency of treatment of uranium-containing wastewater, improve the liquid-solid phase separation during the process, and reduce the disposal cost, it is important to develop low-cost and easily available uranium sorbents. The capability of coalescent utilization of banyan leaves (BL) and activated sludge (AS) for removal of uranium from uranium-containing wastewater are studied. The experimental results show that the coalescent utilization of BL and AS as a uranium sorbent demonstrates a remarkable synergic effect. The uranium removal percentage is 89.6% with BL-AS combination in comparison with 19.2% and 29.4% with AS or BL alone. Various influencing factors are investigated. As the solution pH increase the removal of U goes up first and then drops down with a maximum occurring at pH=3.5. Moderate aeration (80-100 h/L) helps the uranium adsorption, over- or under- aeration lowers the uranium removal. Although the increase of the initial uranium concentration leads to more uranium adsorbed by unit mass of BL-AS adsorbent, but lower the uranium removal ratio, i.e. causes a higher residual concentration of uranium. The adsorption of uranium on BL-AS adsorbent may be equally well described by Freundlich and Langmuir isotherm. (authors)

  15. Functioning of microbial complexes in aerated layers of a highmoor peat bog

    Science.gov (United States)

    Golovchenko, A. V.; Bogdanova, O. Yu.; Stepanov, A. L.; Polyanskaya, L. M.; Zvyagintsev, D. G.

    2010-09-01

    Monitoring was carried out using the luminescent-microscopic method of the abundance parameters of different groups of microorganisms in a monolith and in the mixed layers of a highmoor peat bog (oligotrophic residual-eutrophic peat soil) in a year-long model experiment. The increase of the aeration as a result of mixing of the layers enhanced the activity of the soil fungi. This was attested to by the following changes: the increase of the fungal mycelium length by 6 times and of the fungal biomass by 4 times and the double decrease of the fraction of spores in the fungal complex. The response of the fungal complex to mixing was different in the different layers of the peat bog. The maximal effect was observed in the T1 layer and the minimal one in the T2 layer. The emission of CO2 in the mixed samples was 1.5-2 times higher than that from the undisturbed peat samples. In contrast with the fungi, the bacteria and actinomycetes were not affected by the aeration of the highmoor layers.

  16. ETHANOL PRODUCTION FROM XYLOSE AND WOOD HYDROLYZATE BY MUCOR INDICUS AT DIFFERENT AERATION RATES

    Directory of Open Access Journals (Sweden)

    Ria Millati

    2008-11-01

    Full Text Available The fungus Mucor indicus is able to produce ethanol from xylose as well as dilute-acid lignocellulosic hydrolyzates. The fungus completely assimilated 10 g/L xylose as the sole carbon and energy source within 32 to 65 h at an aeration rate of 0.1 to 1.0 vvm. The highest ethanol yield was 0.16 g/g at 0.1 vvm. Xylitol was formed intermediately with a maximum yield of 0.22 g/g at 0.5 vvm, but disappeared towards the end of experiments. During cultivation in a mixture of xylose and glucose, the fungus did not assimilate xylose as long as glucose was present in the medium. The anaerobic cultivation of the fungus in the hydrolyzate containing 20% xylose and 80% hexoses resulted in no assimilation of xylose but complete consumption of the hexoses in less than 15 h. The ethanol yield was 0.44 g/g. However, the xylose in the hydrolyzate was consumed when the media was aerated at 0.067 to 0.333 vvm. The best ethanol yield was 0.44 g/g at 0.067 vvm. The results of this study suggest that M. indicus hydrolyzate can be first fermented anaerobically for hexose assimilation and subsequently continued under oxygen-limited conditions for xylose fermentation.

  17. Cytosine modifications after gamma irradiation in aerated aqueous solution of Escherichia coli DNA

    International Nuclear Information System (INIS)

    After gamma irradiation of cytosine in aerated aqueous solution and utilization of various spectrometric methods (mass spectrometry, proton nuclear magnetic resonance and infrared spectrometry) about ten new radiolysis products were identified. The formation of N-glycolylbiuret in H218O aqueous solution of irradiated cytosine at pH 4,5 indicated that the preferred 18OH hydroxyl radical attack was at C-5. The formation of trans 1-carbamoyl-4,5 dihydroxyimidazolidin-2 oxo which is the major product after cytosine pyrimidine ring rearrangement took place preferentially at neutral pH, while N-glycolylbiuret predominated at pH 4,5. The deamination pathway was predominant when cytosine was irradiated at acidic pH values (pH2) or in copper complexes. The development of a new acid hydrolysis method using fluorhydric acid stabilized in pyridine made easier the evaluation of cytosine modifications after gamma irradiation in aerated aqueous solution of E. Coli DNA-14C-2 cytosine. This hydrolytic agent removed the modified bases from the polynucleotidic chain. A difference was found between the proportion of radiolytic products removed by acid hydrolysis and by irradiation of the free base in solution

  18. Variability of Energy Dissipation and Shear Rate with Geometry in Unbaffled Surface Aerator

    Directory of Open Access Journals (Sweden)

    Bimlesh Kumar

    2009-12-01

    Full Text Available mixing in surface aerators. At constant dynamic variables (rotational speed, both  and γ are greatly affected by the geometric parameters (impeller diameter, cross-sectional area of the tank, liquid height, rotor blade length and immersion height. By doing numerical computation by VISIMIX ®, present work analyzes the effect of non-dimensional (which is non-dimensionalized through rotor diameter geometric parameters on e and g. With an increase in liquid height, there is an increase in the case of energy dissipation and shear rate values. In the case of tank area and blade length, it is vice versa. Energy dissipation and shear rate are not affected by the variation in immersion height of the impeller. © 2009 BCREC UNDIP. All rights reserved[Received: 17 October 2009, Revised: 12 December 2009, Accepted: 20 December 2009][How to Cite: B. Kumar. (2009. Variability of Energy Dissipation and Shear Rate with Geometry in Unbaffled Surface Aerator. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 55-60. doi:10.9767/bcrec.4.2.30.55-60][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.2.30.55-60

  19. Variability of Energy Dissipation and Shear Rate with Geometry in Unbaffled Surface Aerator

    Directory of Open Access Journals (Sweden)

    Bimlesh Kumar

    2009-12-01

    Full Text Available mixing in surface aerators. At constant dynamic variables (rotational speed, both  and γ are greatly affected by the geometric parameters (impeller diameter, cross-sectional area of the tank, liquid height, rotor blade length and immersion height. By doing numerical computation by VISIMIX ®, present work analyzes the effect of non-dimensional (which is non-dimensionalized through rotor diameter geometric parameters on e and g. With an increase in liquid height, there is an increase in the case of energy dissipation and shear rate values. In the case of tank area and blade length, it is vice versa. Energy dissipation and shear rate are not affected by the variation in immersion height of the impeller. © 2009 BCREC UNDIP. All rights reserved[Received: 17 October 2009, Revised: 12 December 2009, Accepted: 20 December 2009][How to Cite: B. Kumar. (2009. Variability of Energy Dissipation and Shear Rate with Geometry in Unbaffled Surface Aerator. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 55-60. doi:10.9767/bcrec.4.2.7110.55-60][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.2.7110.55-60 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7110

  20. Microfaunal indicators, Ciliophora phylogeny and protozoan population shifts in an intermittently aerated and fed bioreactor

    International Nuclear Information System (INIS)

    Microfauna community structure was examined in the mixed liquor of a bench-scale bioreactor equipped with an intermittent aeration and feeding system. The reactor was operated under an intermittent aeration of 25 min in every 1 h and varying feeding conditions (0.264, 0.403 and 0.773 kg BOD5/m3 d). A total of 14 protozoan and metazoan taxa were identified by microscopic examination. Sessile ciliates, followed by crawling ciliates, were the major protozoan groups under 0.403 kg BOD5/m3 d organic loading conditions, while sessile ciliate population was remarkably increased under an organic loading of 0.773 kg BOD5/m3 d. Principal Component Analysis and Pearson correlation coefficient tests were performed in order to reveal relationships between microfauna community and operational parameters. Ciliophora specific-18S rRNA gene clone library was constructed to identify ciliate diversity under 0.773 kg BOD5/m3 d organic loading conditions. Ciliophora diversity consisted of members of Aspidiscidae, Epistylidae, Opisthonectidae and Vorticellidae, with the majority of the clones being associated with the species Vorticella fusca. At least one novel phylogenetic linkage among Ciliophora was identified. Comparisons made after molecular characterization and microscopic examination of Ciliophora community showed that the estimation of broad ciliate groups is useful for ecological considerations and evaluation of the operational conditions in wastewater treatment plants.

  1. Simultaneous removal of COD and nitrogen using a novel carbon-membrane aerated biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A membrane aerated biofilm reactor is a promising technology for wastewater treatment. In this study, a carbon-membrane aerated biofilm reactor (CMABR) has been developed, to remove carbon organics and nitrogen simultaneously from one reactor. The results showed that CMABR has a high chemical oxygen demand (COD) and nitrogen removal efficiency, as it is operated with a hydraulic retention time (HRT) of 20 h, and it also showed a perfect performance, even if the HRT was shortened to 12 h. In this period, the removal efficiencies of COD, ammonia nitrogen (NH4+-N), and total nitrogen (TN) reached 86%, 94%, and 84%, respectively. However,the removal efficiencies of NH4+-N and TN declined rapidly as the HRT was shortened to 8 h. This is because of the excessive growth of biomass on the nonwoven fiber and very high organic loading rate. The fluorescence in situ hybridization (FISH) analysis indicated that the ammonia oxidizing bacteria (AOB) were mainly distributed in the inner layer of the biofilm. The coexistence of AOB and eubacteria in one biofilm can enhance the simultaneous removal of COD and nitrogen.

  2. Application of blowless exhaust light and aeration panels for TPP and NPP main buildings with skylightless roof

    International Nuclear Information System (INIS)

    Experience of operation of exhaust light and aeration panels with V- like vertical flaps for ntural air removal in turbine halls of NPP with WWER-1000 was anayzed. The panels differ from the known domestic and foreign ones by protection of aeration exhaust openings from wind and atmospheric precipitations. Blowlessness of the openings, as experimnts with smoked air flows showed, is explained by the fact that the region of high pressure forms in flap corbers, and the air flows along flap planes to unprotected part of the panels

  3. Increased puerarin biosynthesis during in vitro shoot formation in Pueraria tuberosa grown in growtek bioreactor with aeration

    OpenAIRE

    Sharma, Varsha; Goyal, Shaily; Ramawat, Kishan G.

    2011-01-01

    Puerarin accumulation during shoot cultures in static and liquid medium with or without aeration is described in Pueraria tuberosa (Roxb. ex Willd.) DC. Maximum shoot induction from nodal explants was achieved on Murashige and Skoog’s medium supplemented with 1.13 μM TDZ and 0.25 μM IBA after 4 weeks of growth. Puerarin content was higher in shoot cultures grown in liquid medium as compared to static medium. When shoots were grown in growtek bioreactor with different aeration volume, maximum ...

  4. Estimation of protective ability of soil-ground of aeration zone within the boundaries of the Chernobyl' NPP radiogeochemical effect

    International Nuclear Information System (INIS)

    The technique for numerical estimation of the soil-ground protective ability in the aeration zone for the Chernobyl' NPP region, which is determined by sorption because of wide ground water use as the main source of auxiliary and drinking water supply is described. Histograms for Cs-137 and Sr-90 distribution in soil-grounds, coefficients of Cs-137 and Sr-90 distribution in sandy-loamy grounds, are the effects of ground type in aeration zone on Cs-137 and Sr-90 absorption are estimated. The calculation scheme for soil-ground, and ground water protective abilities against long-living radionuclide effects is given. 10 refs.; 3 figs.; 1 tab

  5. Effect of light and aeration on the metamorphosis rate from nauplii to protozoea and larval quality of Litopenaeus vannamei

    OpenAIRE

    Hadja Radtke Nunes; Edemar Roberto Andreatta

    2010-01-01

    In order to determine the optimal ranges of the factors light intensity and aeration that reflect the best rate of metamorphosis from nauplii to the first protozoea stage of Litopenaeus vannamei, and also the highest quality of the larvae, two separate experiments were carried out. The nauplii were exposed to four different light intensities (0; 5,000; 10,000; and 15,000 lux) and four aeration conditions (static, low, medium and strong). The data were subjected to one-way ANOVA (significance ...

  6. Autoclaved aerated concrete masonry with external insulation. Features of moisture conditions during the initial period of operation (rus

    Directory of Open Access Journals (Sweden)

    Kuptaraeva P.D.

    2011-12-01

    Full Text Available Building designs at the moment of commissioning include the initial (building and technological moisture. Thermal insulation systems influence on the yield of the initial moisture from the structures. However, there are no specific design requirements about determining initial moisture content in insulation systems.In this article the features of the initial period of operation on an example of aerated concrete are defined: the results of field surveys and calculations are shown and compared. On the basis of this comparison basic advice on the accounting features of the initial period of operation of autoclaved aerated concrete structures with external insulation are given.

  7. Study on the test of oxygen effect of aerator in pond%增氧机池塘增氧效果试验的研究

    Institute of Scientific and Technical Information of China (English)

    张祝利; 顾海涛; 何雅萍; 门涛; 吴为国

    2012-01-01

    研究不同型式的增氧机性能,可使生产者根据不同养殖对象与模式针对溶氧的需求,选择配置合适的增氧方式.通过对使用最为广泛的叶轮式、水车式、射流式和曝气式增氧机产品性能的池塘实效试验,分析比较各类增氧机性能、工作特性和适用范围.结果表明,养殖水体溶解氧主要来自浮游植物的光合作用;叶轮式、水车式和射流式增氧机应用于服务水域,其增氧能力远远不能满足该水域养殖鱼类的氧需求,但可满足养殖鱼类的应急氧需求;曝气式增氧机因没有应急增氧作用和水体搅拌能力而不适合四大家鱼等常规鱼种的养殖需要.%With the development of aquaculture aeration technology,the continuous appearance of various types of aerobic machineries adapts to the needs of different aquaculture.Researching the performance of different types of aerators can help the producers select appropriate aeration manners,which is based on the demand of dissolved oxygen according to different culture species and models.According to the experiment of the effect of impeller aerator,paddlewheel aerator,jet aerators and aeration aerator in the pond which are most widely used,we analyzed the aerator performance,operating characteristics and applicability.The result showed that the dissolved oxygen of aquaculture water mainly comes from the photosynthesis of phytoplankton.When impeller aerator,paddlewheel aerator and jet aerators apply to its service water,their aerobic capacities are far from the oxygen demands of the hshes which cultured in the water,however,it can meet the emergency oxygen demands of cultured fishes.Aeration aerator is not suitable for culturing the four major Chinese carps because it is lack of emergency oxygen effect and water mixing capacity.

  8. Sidestream Elevated Pool Aeration, a Technology for Improving Water Quality in Urban Rivers

    Science.gov (United States)

    Motta, D.; Garcia, T.; Abad, J. D.; Bombardelli, F. A.; Waratuke, A.; Garcia, M. H.

    2010-12-01

    Dissolved Oxygen (DO) levels are frequently depleted in rivers located in urban areas, as in the case of the Matanza-Riachuelo River in Buenos Aires, Argentina. This stream receives both domestic and industrial loads which have received minor or no treatment before being discharged into the water body. Major sources of pollution include, but are not limited, to leather and meat packing industries. Additionally, deep slow moving water in the river is associated with limited reaeration and facilitates deposition of organic-rich sediment, therefore exacerbating the DO consumption through sediment oxygen demand. In this study we assessed the efficiency of Sidestream Elevated Pool Aeration (SEPA) stations as a technology for alleviating conditions characterized by severely low DO levels. A SEPA station takes water from the stream at low DO concentrations, through a screw pump; then, water is transported to an elevated pool from where it flows over a series of weirs for water reaeration; finally, the aerated water is discharged back into the river sufficiently downstream from the intake point. This system mimics a phenomenon that occurs in mountain streams, where water is purified by bubbling over rocks. The impact of the use of SEPA stations on the DO concentrations in the Matanza-Riachuelo River was evaluated at both local and reach scales: this was done by deploying and monitoring an in situ pilot SEPA station, and by performing numerical modeling for the evaluation of the hydrodynamics in the SEPA station and the water quality in the reach where SEPA stations are planned to be implemented. An efficiency of aeration of 99% was estimated from DO measurements in the pilot SEPA, showing the potential of this technology for DO recovery in urban streams. Three-dimensional hydrodynamic modeling, besides assisting in the design of the pilot SEPA, has allowed for designing a prototype SEPA to be built soon. Finally, one-dimensional water quality modeling has provided the

  9. How absolute EIT reflects the dependence of unilateral lung aeration on hyper-gravity and weightlessness?

    International Nuclear Information System (INIS)

    We studied the influence of three gravity levels (0, 1 and 1.8 g) on unilateral lung aeration in a left lateral position by the application of absolute electrical impedance tomography. The electrical resistivity of the lung tissue was considered to be a meaningful indicator for lung aeration since changes in resistivity have already been validated in other studies to be proportional to changes in lung volume. Twenty-two healthy volunteers were studied during parabolic flights with three phases of different gravity, each lasting ∼20–22 s. Spontaneous breathing at normal tidal volume VT and at increased VT was performed. During transition to hyper-gravity mean expiratory resistivities (±SD in Ωm) increased at normal VT in the upper (right) lung from 7.6 ± 1.5 to 8.0 ± 1.7 and decreased from 5.8 ± 1.2 to 5.7 ± 1.2 in the lower (left) lung. Inspiratory resistivity values are 8.3 ± 1.6 to 8.8 ± 1.8 (right) and 6.3 ± 1.3 to 6.0 ± 1.3 (left). At increased VT, the changes in resistivities at end-expiration were 7.7 ± 1.5 to 8.0 ± 1.7 (right) and 5.8 ± 1.2 to 5.7 ± 1.2 (left). Corresponding end-inspiratory values are 9.9 ± 1.9 to 10.0 ± 2.0 (right) and 8.6 ± 2.1 to 7.9 ± 2.0 (left). During weightlessness, the distortion in the lungs disappeared and both lungs showed a nearly identical aeration, which was between the levels displayed at normal gravity. The small increase in resistivity for the upper lung during transition to hyper-gravity from 1 to 1.8 g at increased VT suggests that the degressive part of the pressure–volume curve has already been reached at end-inspiration. The results for a left lateral position are in agreement with West's lung model which has been introduced for cranio-caudal gravity dependence in the lungs. (paper)

  10. Recirculation or artificial aeration in vertical flow constructed wetlands: a comparative study for treating high load wastewater.

    Science.gov (United States)

    Foladori, Paola; Ruaben, Jenny; Ortigara, Angela R C

    2013-12-01

    Vertical subsurface-flow constructed wetlands at pilot-scale have been applied to treat high hydraulic and organic loads by implementing the following configurations: (1) intermittent recirculation of the treated wastewater from the bottom to the top of the bed, (2) intermittent artificial aeration supplied at the bottom of the bed and (3) the combination of both. These configurations were operated with a saturated bottom layer for a 6h-treatment phase, followed by a free drainage phase prior to a new feeding. COD removal efficiency was 85-90% in all the configurations and removed loads were 54-70 gCOD m(-2)d(-1). The aerated and recirculated wetland resulted in a higher total nitrogen removal (8.6 gN m(-2)d(-1)) due to simultaneous nitrification/denitrification, even in the presence of intermittent aeration (6.8 Nm(3)m(-2)d(-1)). The extra investment needed for implementing aeration/recirculation would be compensated for by a reduction of the surface area per population equivalent, which decreased to 1.5m(2)/PE. PMID:24128403

  11. Development and on-site field testing of the power-tube airlift aerator and chances for commercialization

    Science.gov (United States)

    Aeration of ponds when dissolved oxygen (DO) concentrations are low is the principal management tool that allows for higher feeding rates, increased production, and decreased cost per unit fish produced. Recent research conducted at the USDA-ARS Warmwater Aquaculture Research Unit has shown that fee...

  12. Application of airlift bioreactor for the cultivation of aerobic oleaginous yeast Rhodotorula glutinis with different aeration rates.

    Science.gov (United States)

    Yen, Hong-Wei; Liu, Yi Xian

    2014-08-01

    The high cost of microbial oils produced from oleaginous microorganisms is the major obstacle to commercial production. In this study, the operation of an airlift bioreactor is examined for the cultivation of oleaginous yeast-Rhodotorula glutinis, due to the low process cost. The results suggest that the use of a high aeration rate could enhance cell growth. The maximum biomass concentration of 25.40 g/L was observed in the batch with a 2.0 vvm aeration rate. In addition, a higher aeration rate of 2.5 vvm could achieve the maximum growth rate of 0.46 g/L h, about twice the 0.22 g/L h obtained in an agitation tank. However, an increase in tank pressure instead of the aeration rate did not enhance cell growth. The operation of airlift bioreactor described in this work has the advantages of simple operation and low energy consumption, thus making it suitable for the accumulation of microbial oils. PMID:24503421

  13. INFLUENCE OF SODIUM GLUTAMATE, BUBBLING N2- GAS AND SUPERFICIAL AERATION ON TETANUS TOXIN PRODUCTION IN Clostridium tetani CULTURES

    Directory of Open Access Journals (Sweden)

    I. Gutiérrez

    2005-12-01

    Full Text Available The influence of sodium glutamate as a supplement to Latham Mueller medium, while using bubbling nitrogen flow as an anaerobic agent and superficial aeration as an inducer of cell lysis and as a mechanism for the haulage of gases in the fermentation processes was evaluated. Using the Clostridium tetani Massachusetts’s strain, several five (5 liter batch fermentations were carried out for tetanus toxin production under the following conditions: Latham Mueller medium, with or without sodium glutamate, nitrogen flow and superficial aeration. The results demonstrated that the addition of sodium glutamate (2.5 g/l, combined with a bubbling nitrogen flow (0.33 l/min and superficial aeration (0.33 l/min, produced a significant increase in cell concentrations, repressing the tetanus toxin formation; while the gas flow (nitrogen and superficial aeration without sodium glutamate improved the toxin production by approximately 49%, providing conditions for the following outcomes: a maximum toxin level of 73 Lf/ml; a toxin formation rate of 1844.0 Lf/l.h; and, an over-all productivity of 833.5 Lf/l.h.

  14. Preparation and sensory perception of fat-free foams : Effect of matrix properties and level of aeration

    NARCIS (Netherlands)

    Minor, M.; Vingerhoeds, M.H.; Zoet, F.D.; Wijk, de R.A.; Aken, van G.A.

    2009-01-01

    The sensory perception of fat-free model foams with a consistency between pourable (liquid; xanthan thickened) and spoonable (semi-solid; gelled; carrageenan thickened) and varying level of aeration was studied. At low air contents (5, 10% v/v) perception is largely determined by the matrix properti

  15. Effect of aeration rate, moisture content and composting period on availability of copper and lead during pig manure composting.

    Science.gov (United States)

    Shen, Yujun; Zhao, Lixin; Meng, Haibo; Hou, Yueqing; Zhou, Haibin; Wang, Fei; Cheng, Hongsheng; Liu, Hongbin

    2016-06-01

    Pollution by heavy metals, such as copper and lead, has become a limiting factor for the land application of faecal manures, such as pig manure. This study was conducted to investigate the influence of composting process parameters, including aeration rate, moisture content and composting period, on the distribution of heavy metal species during composting, and to select an optimal parameter for copper and lead inactivation. Results showed that the distribution ratios of exchangeable fractions of copper and lead had a bigger decrease under conditions of aeration rate, 0.1 m(3) min(-1) m(-3), an initial moisture content of 65% and composting period of 50 days. Suboptimal composting process conditions could lead to increased availability of heavy metals. Statistical analysis indicated that the aeration rate was the main factor affecting copper and lead inactivation, while the effects of moisture content and composting period were not significant. The rates of reduction of copper-exchangeable fractions and lead-exchangeable fractions were positively correlated with increased pH. The optimal parameters for reducing heavy metal bioavailability during pig manure composting were aeration rate, 0.1 m(3) min(-1) m(-3), initial moisture content, 65%, and composting period, 20 days. PMID:27067429

  16. Reducing Volatile Disinfection By-Products in Treated Drinking Water Using Aeration Technologies (WaterRF Report 4441)

    Science.gov (United States)

    The primary objective of this project was to evaluate cost-effective aeration technology solutions to address TTHM compliance at a water treatment plant clearwell. The project team worked closely with EPA Region 6 and the EPA Office of Research and Development (ORD) to identify a...

  17. Fibrous Support Stabilizes Nitrification Performance of a Membrane-Aerated Biofilm: The Effect of Liquid Flow Perturbation

    DEFF Research Database (Denmark)

    Terada, Akihiko; Ito, J; Matsumoto, S;

    2009-01-01

    Nitrification stability and biofilm robustness were examined by comparing a fibrous support membrane-aerated biofilm reactor (FS-MABR), where a woven fibrous support was surrounded on a silicone tube, with an MABR. The overall mass transfer coefficient of oxygen for the FS-MABR, assuming no...

  18. Enhanced recovery of ammonia from swine manure anaerobic digester effluent using gas-permeable membranes and aeration

    Science.gov (United States)

    Atmospheric ammonia pollution from livestock wastes can be reduced using gas-permeable membrane technology by converting ammonia contained in the manure into ammonium salt for use in fertilizers. In this study, gas-permeable membrane technology was enhanced using aeration combined with nitrificatio...

  19. Effects of subsurface aeration and trinexapac-ethyl application on soil microbial communities in a creeping bentgrass putting green

    Science.gov (United States)

    Feng, Y.; Stoeckel, D.M.; Van Santen, E.; Walker, R.H.

    2002-01-01

    The sensitivity of creeping bentgrass (Agrostis palustris Huds.) to the extreme heat found in the southeastern United States has led to the development of new greens-management methods. The purpose of this study was to examine the effects of subsurface aeration and growth regulator applications on soil microbial communities and mycorrhizal colonization rates in a creeping bentgrass putting green. Two cultivars (Crenshaw and Penncross), a growth regulator (trinexapacethyl), and subsurface aeration were evaluated in cool and warm seasons. Total bacterial counts were higher in whole (unsieved) soils than in sieved soils, indicating a richer rhizosphere soil environment. Mycorrhizal infection rates were higher in trinexapac-ethyl (TE) treated plants. High levels of hyphal colonization and relatively low arbuscule and vesicle occurrence were observed. Principal components analysis of whole-soil fatty acid methyl ester (FAME) profiles indicated that warm-season microbial populations in whole and sieved soils had similar constituents, but the populations differed in the cool season. FAME profiles did not indicate that subsurface aeration and TE application affected soil microbial community structure. This is the first reported study investigating the influences of subsurface aeration and TE application on soil microorganisms in a turfgrass putting green soil.

  20. Evaluation of design factors for a cascade aerator to enhance the efficiency of an oxidation pond for ferruginous mine drainage.

    Science.gov (United States)

    Oh, Chamteut; Ji, Sangwoo; Cheong, Youngwook; Yim, Giljae; Hong, Ji-Hye

    2016-10-01

    This research focused on the optimum design of a cascade aerator to enhance the efficiency of an oxidation pond in a passive treatment system for remediating ferruginous mine drainage. For this purpose, various aeration experiments with aerators of different drop heights (0-4 m) and formations (types A and B) were executed on mine drainage. Type A simply drops the mine drainage into the oxidation pond while type B sprays the mine drainage and retains it for 8 min in each step. The efficiency enhancement of the oxidation pond was strongly dependent on the increase in pH and DO of the mine drainage discharged into the pond. The water quality improved with the increase in drop height but especially showed better effect with type B. The reasons for this result were attributed to the increase of contact surface and retention time of the mine drainage. The cascade aerator, therefore, should be designed to be as high as possible with the assistance of spraying form and retention time of the mine drainage to maximize the efficiency of the oxidation pond. These effects could be evaluated by calculating required areas of the oxidation pond for 95% of Fe(2+) oxidation. PMID:26936197

  1. Automatic adjustment of cycle length and aeration time for improved nitrogen removal in an alternating activated sludge process

    DEFF Research Database (Denmark)

    Isaacs, Steven Howard

    1997-01-01

    The paper examines the nitrogen dynamics in the alternating BIODENITRO and BIODENIPHO processes with a focus on two control handles influencing now scheduling and aeration: the cycle length and the ammonia concentration at which a nitrifying period is terminated. A steady state analysis examining...

  2. Modeling enzyme production with Aspergillus oryzae in pilot scale vessels with different agitation, aeration, and agitator types

    DEFF Research Database (Denmark)

    Albæk, Mads Orla; Gernaey, Krist; Hansen, Morten S.;

    2011-01-01

    tank reactors. Different conditions of agitation and aeration were employed as well as two different impeller geometries. The limiting factor for the productivity was oxygen supply to the fermentation broth, and the carbon substrate feed flow rate was controlled by the dissolved oxygen tension. In...

  3. Framework for Energy Neutral Treatment for the 21st Century Through Energy Efficient Aeration (WERF Report INFR2R12)

    Science.gov (United States)

    Aeration is commonly identified as the most significant energy use in the treatment of wastewater and therefore garners significant focus in reducing energy use in the ultimate aspirational goal of achieving net energy neutrality for water resource recovery. This research establi...

  4. Effect of Stirrer Speed and Aeration Rate on the Production of Glucose Oxidase by Aspergillus niger

    Directory of Open Access Journals (Sweden)

    Jafari A.R.

    2007-01-01

    Full Text Available Dissolved oxygen tension and shear stress as two very important factors in fungal fermentation were studied in the batch cultures of Aspergillus niger. The intention was to maximize the total activity of glucose oxidase produced in a 5-1 bench-top bioreactor. 300 rpm found to be optimum for enzyme production, however in higher mixing rates higher growth was achieved. The maximum activity of glucose oxidase was obtained in 1.5 vvm while the best aeration rate for growth was 2 vvm. Glucose oxidase with the activity of 548 U mL-1 was produced in 1.5 vvm and 300 rpm as the optimum conditions.

  5. Maximizing the xylitol production from sugar cane bagasse hydrolysate by controlling the aeration rate

    Energy Technology Data Exchange (ETDEWEB)

    Silva, S.S.; Ribeiro, J.D.; Felipe, M.G.A. [Faculty of Chemical Enginering of Lorena (Brazil); Vitolo, M. [Univ. of Sao Paulo (Brazil)

    1997-12-31

    Batch fermentations of sugar cane bagasse hemicellulosic hydrolysate treated for removing the inhibitors of the fermentation were performed by Candida guilliermondii FTI 20037 for xylitol production. The fermentative parameters agitation and aeration rate were studied aiming the maximization of xylitol production from this agroindustrial residue. The maximal xylitol volumetric productivity (0.87 g/L {center_dot} h) and yield (0.67 g/g) were attained at 400/min and 0.45 v.v.m. (K{sub L}a 27/h). According to the results, a suitable control of the oxygen input permitting the xylitol formation from sugar cane bagasse hydrolysate is required for the development of an efficient fermentation process for large-scale applications. 20 refs., 2 figs.

  6. Aeration and mass transfer optimization in a rectangular airlift loop photobioreactor for the production of microalgae.

    Science.gov (United States)

    Guo, Xin; Yao, Lishan; Huang, Qingshan

    2015-08-01

    Effects of superficial gas velocity and top clearance on gas holdup, liquid circulation velocity, mixing time, and mass transfer coefficient are investigated in a new airlift loop photobioreactor (PBR), and empirical models for its rational control and scale-up are proposed. In addition, the impact of top clearance on hydrodynamics, especially on the gas holdup in the internal airlift loop reactor, is clarified; a novel volume expansion technique is developed to determine the low gas holdup in the PBR. Moreover, a model strain of Chlorella vulgaris is cultivated in the PBR and the volumetric power is analyzed with a classic model, and then the aeration is optimized. It shows that the designed PBR, a cost-effective reactor, is promising for the mass cultivation of microalgae. PMID:25958141

  7. Winery wastewater treatment by a combined process: long term aerated storage and Fenton's reagent.

    Science.gov (United States)

    Lucas, Marco S; Mouta, Maria; Pirra, António; Peres, José A

    2009-01-01

    The degradation of the organic pollutants present in winery wastewater was carried out by the combination of two successive steps: an aerobic biological process followed by a chemical oxidation process using Fenton's reagent. The main goal of this study was to evaluate the temporal characteristics of solids and chemical oxygen demand (COD) present in winery wastewater in a long term aerated storage bioreactor. The performance of different air dosage daily supplied to the biologic reactor, in laboratory and pilot scale, were examined. The long term hydraulic retention time, 11 weeks, contributed remarkably to the reduction of COD (about 90%) and the combination with the Fenton's reagent led to a high overall COD reduction that reached 99.5% when the mass ratio (R = H(2)O(2)/COD) used was equal to 2.5, maintaining constant the molar ratio H(2)O(2)/Fe(2+)=15. PMID:19700849

  8. Removal of diclofenac from surface water by electron beam irradiation combined with a biological aerated filter

    Science.gov (United States)

    He, Shijun; Wang, Jianlong; Ye, Longfei; Zhang, Youxue; Yu, Jiang

    2014-12-01

    The degradation of DCF was investigated in aqueous solution by using electron beam (EB) technology. When the initial concentration was between 10 and 40 mg/L, almost 100% of the DCF was degraded at a dose of 0.5 kGy. However, only about 6.5% of DCF was mineralized even at 2 kGy according to total organic carbon (TOC) measurements. A combined process of EB and biological aerated filter (BAF) was therefore developed to enhance the treatment of DCF contaminated surface water. The effluent quality of combined process was substantially improved by EB pretreatment due to the degradation of DCF and related intermediates. Both irradiation and biological treatment reduced the toxicity of the treated water. The experimental results showed that EB is effective for removing DCF from artificial aqueous solution and real surface water.

  9. Utilization of Ecosand and Flyash in Aerated Concrete for a Richest Mix Design

    Directory of Open Access Journals (Sweden)

    M. Thenmozhi

    2011-01-01

    Full Text Available Aerated concrete is made by introducing air or gas into slurry composed of portland cement and finely crushed siliceous filler, so that when the mix sets and hardens uniformly cellular structure is formed. Thus it is a mixture of water, cement and finely crushed sand. By using finely powdered metal aluminium powder with the slurry and made to react with the calcium hydroxide liberated during the hydration process to give out large quantity of hydrogen gas. This hydrogen gas when contained in the slurry mix gives the cellular structure. This study involves the use of fly ash eco-sand, a byproduct of cement as filler material, aluminium powder as metalpowder, hydrogen peroxide as foaming agent and OPC 43 grade cement as binder. This product emphasizes its economic feasibility when compared with the commonly produced AAC.

  10. Effect of media heights on the performance of biological aerated filter

    Institute of Scientific and Technical Information of China (English)

    HU Yong-you; WANG Li-li

    2005-01-01

    The optimum media height of carbon oxidation and nitrification in a down-flow biological aerated filter was determined, and the distribution of the heterotrophic and nitrifying populations through studying the changes of organic carbon contents and ammonia concentration at different media height was got. The results showed that as a down flow BAF with granular media, the active layer of nitrifiers was deeper than heterotrophs in BAF. And the optimum media height for the removal of SS, CODCr and NH4+ -N was 40 cm,60 cm and 80 cm respectively. The removal efficiency of SS, CODCr and NH4+-N was 79.1%, 63.9% and 96.4% respectively under the influent CODCr and NH4+ -N of 122.1 mgCODCr/L and 14.84 mgNH4+ -N/L, the influent flux of 15.8 L/h, air to liquid ratio of 3: 1.

  11. Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae

    Science.gov (United States)

    Klein, H. P.; Jahnke, L.

    1979-01-01

    Previous studies on the yeast Saccharomyces cerevisiae have shown that two different forms of the enzyme acetyl coenzyme A synthetase (ACS) are present, depending on the conditions under which the cells are grown. The paper evaluates the usefulness of a method designed to assay both synthetases simultaneously in yeast homogenates. The data presented confirm the possibility of simultaneous detection and estimation of the amount of both ACSs of S. cerevisiae in crude homogenates of this strain, making possible the study of physiological factors involved in the formation of these isoenzymes. One important factor for specifying which of the two enzymes is found in these yeast cells is the presence or absence of oxygen in their environment. Aeration not only affects the ratio of the two ACSs but also appears to affect the cellular distribution of these enzymes. Most of the data presented suggest the possibility that the nonaerobic ACS may serve as a precursor to the aerobic form.

  12. Influence of water cavitation peening with aeration on fatigue behaviour of SAE1045 steel

    International Nuclear Information System (INIS)

    Water cavitation peening (WCP) with aeration is a recent potential method in the surface enhancement techniques. In this method, a ventilation nozzle is adopted to improve the process capability of WCP by increasing the impact pressure, which is induced by the bubble collapse on the surface of components in the similar way as conventional shot peening. In this paper, fatigue tests were conducted on the both-edge-notched flat tensile specimens to assess the influences of WCP on fatigue behaviour of SAE1045 steel. The notched specimens were treated by WCP, and the compressive residual stress distributions in the superficial layer were measured by X-ray diffraction method. The tension-tension (R = Smin/Smax = 0.1, f = 10 Hz) fatigue tests and the fracture surfaces observation by scan electron microscopy (SEM) were conducted. The experimental results show that WCP can improve the fatigue life by inducing the residual compressive stress in the superficial layer of mechanical components

  13. Influence of water cavitation peening with aeration on fatigue behaviour of SAE1045 steel

    Science.gov (United States)

    Han, B.; Ju, D. Y.; Jia, W. P.

    2007-10-01

    Water cavitation peening (WCP) with aeration is a recent potential method in the surface enhancement techniques. In this method, a ventilation nozzle is adopted to improve the process capability of WCP by increasing the impact pressure, which is induced by the bubble collapse on the surface of components in the similar way as conventional shot peening. In this paper, fatigue tests were conducted on the both-edge-notched flat tensile specimens to assess the influences of WCP on fatigue behaviour of SAE1045 steel. The notched specimens were treated by WCP, and the compressive residual stress distributions in the superficial layer were measured by X-ray diffraction method. The tension-tension ( R = Smin/ Smax = 0.1, f = 10 Hz) fatigue tests and the fracture surfaces observation by scan electron microscopy (SEM) were conducted. The experimental results show that WCP can improve the fatigue life by inducing the residual compressive stress in the superficial layer of mechanical components.

  14. Treatment of Slightly Polluted Wastewater in an Oil Refinery Using a Biological Aerated Filter Process

    Institute of Scientific and Technical Information of China (English)

    XIE Wenyu; ZHONG Li; CHEN Jianjun

    2007-01-01

    The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids (SS). A small-scale fixed film biological aerated filter (BAF) process was used to treat the wastewater. The influences of hydraulic retention time (HRT), air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions: the HRT of backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5the BAF process is a suitable and highly efficient method to treat the wastewater.

  15. In situ activity recovery of aging biofilm in biological aerated filter: Surfactants treatment and mechanisms study.

    Science.gov (United States)

    Yu, Qisheng; Huang, Hui; Ren, Hongqiang; Ding, Lili; Geng, Jinju

    2016-11-01

    In situ activity recovery of aging biofilm in the biological aerated filter (BAF) is an important but underappreciated problem. Lab-scaled BAFs were established in this study and three kinds of surfactants containing sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and rhamnolipid were employed. Multiple indicators including effluent qualities, dissolved organic matters, biofilm physiology and morphology characteristics were investigated to explore the mechanisms. Results showed that removal rates of effluent COD in test groups significantly recovered to the level before aging. Compared with the control, effluent in SDBS and rhamnolipid-treated groups obtained more protein-like and humic-like substances, respectively. Furthermore, great live cell ratio, smooth surface and low adhesion force of biofilm were observed after rhamnolipid treatment, which was in consistent with good effluent qualities in the same group. This is the first report of applying rhamnolipid for in situ activity recovery of aging biofilm in bioreactors. PMID:27513646

  16. BIOLOGICAL AERATED FILTERS (BAFs FOR CARBON AND NITROGEN REMOVAL: A REVIEW

    Directory of Open Access Journals (Sweden)

    ELSHAFIE AHMED

    2012-08-01

    Full Text Available Biological aerated filters (BAFs are an emerging wastewater treatment technology designed for a wide range of municipal and industrial applications. This review paper presents and discusses of the influence C/N ratio, nitrification and denitrification principle, effect of pH, DO and alkalinity on the nitrification and denitrification systems, organic and hydraulic loading of BAF reactor, etc. Results from upflow and downflow biofilter pilot at different condition, with nitrification and denitrification are reviewed. Under the optimal conditions, significant amount of COD, ammonia-nitrogen and total nitrogen were removed. Removal rates based on reactor volume for different carbon-aceous COD and ammonia loading rate are reported. The BAF system for the nitrification and denitrification processes for carbon and nitrogen removal from the wastewater need to be evaluated and applied properly to protect of our environment and resources.

  17. Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Ruscalleda, Maël; Terada, Akihiko;

    bacterial granules or biofilms. In this sense, completely autotrophic nitrogen removal from high ammonium strength wastewater was achieved in a Membrane-Aereated Biofilm Reactor (MABR) in a single step. Here, a biofilm containing nitrifiers (Aerobic Ammonium and Nitrite Oxidizing Bacteria, AOB and NOB......Due to the necessity of a source of nitrite, most of the processes involving Anaerobic Ammonium Oxidation (Anammox) are based on a separated two-step process with a previous partial-nitritation reactor. However, these two processes can occur simultaneously in the same reactor by taking advantage of......, respectively) and Anaerobic Ammonium Oxidizing Bacteria (AnAOB) is grown on bubbleless aeration membranes to remove ammonium. Since oxygen permeates through the membrane-biofilm interface while ammonium diffuses into the biofilm from the biofilm-liquid interface, oxygen gradients can be established across the...

  18. Immunotoxic potential of aeration lagoon effluents for the treatment of domestic and hospital wastewaters in the freshwater mussel Elliptio complanata

    Institute of Scientific and Technical Information of China (English)

    Francois Gagné; Chantale André; Marlène Fortier; Michel Fournier

    2012-01-01

    Municipal wastewaters are major sources of pollution for the aquatic biota.The purpose of this study was to determine the levels of some pharmaceutical products and the immunotoxic potential of a municipal wastewater aeration lagoon for the treatment of the domestic wastewaters of a small town with wastewater inputs from a 400-bed hospital complex.Endemic mussels were collected,caged and placed in the final aeration lagoon and at sites 1 km upstream and 1 km downstream of the effluent outfall in the receiving river for a period of 14 days.The results showed that the final aeration lagoon contained high levels of total coliforms,conductivity and low dissolved oxygen (2.9 mg/L) as well as detectable amounts of trimethoprim,carbamazepine,gemfibrozil,and norfloxacin at concentrations exceeding 50 ng/L.The lagoon effluent was indeed toxic to the mussel specimens,as evidenced by the appearance of mortality after 14 days (10% mortality),decreased mussel weight-to-shell-length ratio and loss of hemocyte viability.The number of adhering hemocytes,phagocytic activity,total nitrite levels and arachidonic cyclooxygenase activity were significantly higher in mussels placed in the final aeration lagoon.A multivariate analysis also revealed that water pH,conductivity,total coliforms and dissolved oxygen were the endpoints most closely linked with phagocytic activity,the amount of adhering hemocytes and loss of hemocyte viability.In conclusion,exposure of mussels to treated aerated lagoon wastewater is deleterious to freshwater mussels where the immune system is compromised.

  19. Automatic system for quantification and visualization of lung aeration on chest computed tomography images: the Lung Image System Analysis - LISA

    International Nuclear Information System (INIS)

    High Resolution Computed Tomography (HRCT) is the exam of choice for the diagnostic evaluation of lung parenchyma diseases. There is an increasing interest for computational systems able to automatically analyze the radiological densities of the lungs in CT images. The main objective of this study is to present a system for the automatic quantification and visualization of the lung aeration in HRCT images of different degrees of aeration, called Lung Image System Analysis (LISA). The secondary objective is to compare LISA to the Osiris system and also to specific algorithm lung segmentation (ALS), on the accuracy of the lungs segmentation. The LISA system automatically extracts the following image attributes: lungs perimeter, cross sectional area, volume, the radiological densities histograms, the mean lung density (MLD) in Hounsfield units (HU), the relative area of the lungs with voxels with density values lower than -950 HU (RA950) and the 15th percentile of the least density voxels (PERC15). Furthermore, LISA has a colored mask algorithm that applies pseudo-colors to the lung parenchyma according to the pre-defined radiological density chosen by the system user. The lungs segmentations of 102 images of 8 healthy volunteers and 141 images of 11 patients with Chronic Obstructive Pulmonary Disease (COPD) were compared on the accuracy and concordance among the three methods. The LISA was more effective on lungs segmentation than the other two methods. LISA's color mask tool improves the spatial visualization of the degrees of lung aeration and the various attributes of the image that can be extracted may help physicians and researchers to better assess lung aeration both quantitatively and qualitatively. LISA may have important clinical and research applications on the assessment of global and regional lung aeration and therefore deserves further developments and validation studies. (author)

  20. Automatic system for quantification and visualization of lung aeration on chest computed tomography images: the Lung Image System Analysis - LISA

    Energy Technology Data Exchange (ETDEWEB)

    Felix, John Hebert da Silva; Cortez, Paulo Cesar, E-mail: jhsfelix@gmail.co [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Engenharia de Teleinformatica; Holanda, Marcelo Alcantara [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Hospital Universitario Walter Cantidio. Dept. de Medicina Clinica

    2010-12-15

    High Resolution Computed Tomography (HRCT) is the exam of choice for the diagnostic evaluation of lung parenchyma diseases. There is an increasing interest for computational systems able to automatically analyze the radiological densities of the lungs in CT images. The main objective of this study is to present a system for the automatic quantification and visualization of the lung aeration in HRCT images of different degrees of aeration, called Lung Image System Analysis (LISA). The secondary objective is to compare LISA to the Osiris system and also to specific algorithm lung segmentation (ALS), on the accuracy of the lungs segmentation. The LISA system automatically extracts the following image attributes: lungs perimeter, cross sectional area, volume, the radiological densities histograms, the mean lung density (MLD) in Hounsfield units (HU), the relative area of the lungs with voxels with density values lower than -950 HU (RA950) and the 15th percentile of the least density voxels (PERC15). Furthermore, LISA has a colored mask algorithm that applies pseudo-colors to the lung parenchyma according to the pre-defined radiological density chosen by the system user. The lungs segmentations of 102 images of 8 healthy volunteers and 141 images of 11 patients with Chronic Obstructive Pulmonary Disease (COPD) were compared on the accuracy and concordance among the three methods. The LISA was more effective on lungs segmentation than the other two methods. LISA's color mask tool improves the spatial visualization of the degrees of lung aeration and the various attributes of the image that can be extracted may help physicians and researchers to better assess lung aeration both quantitatively and qualitatively. LISA may have important clinical and research applications on the assessment of global and regional lung aeration and therefore deserves further developments and validation studies. (author)

  1. Mechanisms of ammonium transformation and loss in intermittently aerated leachfield soil.

    Science.gov (United States)

    Richard, John T; Potts, David A; Amador, José A

    2014-11-01

    Optimization of N removal in soil-based wastewater treatment systems requires an understanding of the microbial processes involved in N transformations. We examined the fate of NH in intermittently aerated leachfield mesocosms over a 24-h period. Septic tank effluent (STE) was amended with NHCl to help determine N speciation and distribution in drainage water, soil, and headspace gases. Our results show that 5.7% of the N was found in soil, 10.0% in drainage water, and 84.3% in the gas pool. Ammonium accounted for 41.7% of the soil N pool, followed by NO (29.2%), organic N (21.7%), and microbial biomass N (7.5%). In drainage water, NO constituted ∼80% of the N pool, whereas NH was absent from this pool. Nitrous oxide was the dominant form of N in the gas phase 6 h after addition of NH-amended STE to the mesocosms, after which its mass declined exponentially; by contrast, the mass of N was initially low but increased linearly with time to become the dominant form of N after 24 h. Analysis based on the isotopic enrichment of NO and N indicates that nitrification contributed 98.8 and 23.1% of the NO flux after 6 and 24 h, respectively. Our results show that gaseous losses are the main mechanism for NH removal from wastewater in intermittently aerated soil. In addition, nitrification, which is generally not considered a significant pathway for N loss in soil-based wastewater treatment, is an important source process for NO. PMID:25602229

  2. Comparative Study of SMBR and Extended Aeration Activated Sludge Processes in the Treatment of Strength Wastewaters

    Directory of Open Access Journals (Sweden)

    D Motalebi

    2011-10-01

    Full Text Available Background and Objectives: One of the complete treatment processes for industrial and municipal wastewater treatment is membrane bioreactor process which has dominant potential in process and operation sections. This study was conducted to compare the performance of extended aeration activated sludge (EAAS with submerged membrane bioreactor (SMBR systems in the treatment of strength wastewater, in the same condition. Materials and Methods: The initial activated sludge was brought from the Plascokar Saipa wastewater plant. The Plexiglas reactor with effective volume of 758 L was separated by a baffle into the aeration and secondary sedimentation parts with effective volumes of 433 L and 325 L, respectively. The chemical oxygen demand (COD concentration of the influent wastewater of the EAAS and SMBR systems were between 500-2700 and 500-5000 mg/L, respectively.Results: Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand (BOD5, total suspended solids (TSS and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids (MLSS and the removal efficiency of organic matter in the SMBR system, were increased regularly, however the removal efficiency of COD in the EAAS system was irregular. Conclusion: The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708±0.18 and 0.537±0.106, respectively. These show that the organic matters in the effluent of the SMBR system was less degradable and thereupon more biological treatment was achieved. Nitrification process was completely done in the SMBR system while the EAAS system could not achieve to complete nitrification.

  3. Influence of aeration in the fermentative activity of Kloeckera apiculata during fermentation of apple juice

    International Nuclear Information System (INIS)

    The influence of aeration on the fermentative activity of Kloeckera apiculata RIVE 9-2-1 was studied in order to evaluate the production of metabolites of the fermentation. To achieve this, the strain was cultured in Erlenmeyer flasks containing sterilized and aroma removed apple juice, and the chemical compounds produced during fermentation in shaken (200 min-1) and static (without agitation) cultivation were determined. The results showed that the agitation of the culture medium increases production of higher alcohols (till 591.0 mg/L) compared to static cultivation, whereas on the contrary, the production of acetic acid, ethyl acetate and glycerol (260.0 ± 11.0 mg/L, 196.0 ± 10.0 mg/L y 2.6±0.2 g/L) were higher compared to shaken cultivation (222.0 ± 8.0 mg/L, 96.0 ± 4.5 mg/L and 1.8 ± 0.2 g/L) respectively. Batch cultivations carried out in bioreactor with air flux of 25 l/h reported a growth rate μ of 0.17 h-1, production of ethanol (12.5 ± 2.0 g/L) and other compounds typically produced during alcoholic fermentation. The concentration of dissolved oxygen in the fermentation medium affects its metabolism thus; insufficient amounts of oxygen would provoke a respirofermentative metabolism. The best results in terms of organoleptic quality of the fermented beverage regarding to aroma, taste and flavor was obtained when fermented in static cultivation. The control of aeration during fermentation can be used to control the synthesis of chemical compounds of sensory impact in the production of fermented beverages.

  4. Assessing the economic suitability of aeration and the influence of bed heating on constructed wetlands treatment efficiency and life-span

    OpenAIRE

    Labella, Alessandro; Caniani, Donatella; Hughes Riley, Theodore; Morrison, R.; Newton, Michael I.; Hawes, Patrick; Puigagut Juárez, Jaume; García Serrano, Joan; Uggetti, Enrica

    2015-01-01

    Constructed wetlands including aeration and heating were studied to improve treatment efficiency and prevent clogging. The experiments were carried out in a pilot plant (0.4 m(2)) treating urban wastewater with an organic loading rate of 40-60 g COD/m(2) d. Continuous and intermittent aeration was performed from the bottom on 8% of the wetland surface, leading to different dissolved oxygen concentrations within the wetlands (from 0.2 to 5 mg O-2/L). Continuous aeration increased organic matte...

  5. Comparison between lab- and full-scale applications of in situ aeration of an old landfill and assessment of long-term emission development after completion

    International Nuclear Information System (INIS)

    Highlights: ► Current data on in situ aeration effects from the first Austrian full-scale case study. ► Data on lasting waste stabilisation after aeration completion. ► Information on the transferability of results from lab- to full-scale aeration. - Abstract: Sustainable landfilling has become a fundamental objective in many modern waste management concepts. In this context, the in situ aeration of landfills has been recognised for its potential to convert conventional anaerobic landfills into biological stabilised state, whereby both current and potential (long-term) emissions of the landfilled waste are mitigated. In recent years, different in situ aeration concepts have been successfully applied in Europe, North America and Asia, all pursuing different objectives and strategies. In Austria, the first full-scale application of in situ landfill aeration by means of low pressure air injection and simultaneous off-gas collection and treatment was implemented on an old, small municipal solid waste (MSW) landfill (2.6 ha) in autumn 2007. Complementary laboratory investigations were conducted with waste samples taken from the landfill site in order to provide more information on the transferability of the results from lab- to full-scale aeration measures. In addition, long-term emission development of the stabilised waste after aeration completion was assessed in an ongoing laboratory experiment. Although the initial waste material was described as mostly stable in terms of the biological parameters gas generation potential over 21 days (GP21) and respiration activity over 4 days (RA4), the lab-scale experiments indicated that aeration, which led to a significant improvement of leachate quality, was accompanied by further measurable changes in the solid waste material under optimised conditions. Even 75 weeks after aeration completion the leachate, as well as gaseous emissions from the stabilised waste material, remained low and stayed below the authorised

  6. Research on the removal of radium from uranium effluent by air-aeration hydrated manganese hydroxide adsorption

    International Nuclear Information System (INIS)

    In the acidic leaching uranium process, pyrolusite or manganese oxide (MnO2) powder is often used as an oxidizer. In the resulting effluent, manganese ion is present as a contaminant in addition to U, Ra, Th, As, Zn, Cu, F-, SO42-, etc. Manganese ion content is about 100∼200 mg/l in effluent. In this case, a new process technique can be developed to treat the effluent using the Mn2+ present in the effluent. The approach is as follows: The effluent is neutralized by lime milk to pH about 11. As a result, most contaminants are precipitated to meet the uranium effluent discharge standards (U, Th, Mn, SO42- etc), but radium is still present in the effluent. In this process, manganese ion forms manganese hydroxide Mn(OH)2. The manganese hydroxide is easily oxidized to form MnO(OH)2 by air aeration. This hydrated manganese hydroxide complex can then be used to adsorb radium in effluent. The experiments show: (1) Effluent pH, manganese concentration in effluent, and aeration strength and time etc. influence the radium removal efficiency. Under the test conditions, when manganese in effluent is between 100∼300 mg/l, and pH is over 10.5, radium can be reduced to lower than 1.11 Bq/l in the processed effluent. Higher contents of impurity elements such as aluminum, silicon and magnesium in the effluent affect the removal efficiency, (2) Under the experimental conditions, the lime precipitation-air aeration formed hydrated manganese hydroxide complex sludge is stable. There is no obvious release of radium from the adsorbed hydrated manganese hydroxide complex sludge, (3) the current experiments show that hydrated manganese hydroxide complex sludge has very good re-adsorption ability for removal of radium from uranium effluent. Some experimental parameters have been measured, (4) Compared with other process methods, such as neutralizing effluent without aeration; or neutralization with barium chloride addition at pH 5, 8, and 11, the removal of radium from uranium effluent

  7. Odorous gaseous emissions as influence by process condition for the forced aeration composting of pig slaughterhouse sludge

    International Nuclear Information System (INIS)

    Highlights: • The gaseous emissions produced by various composting process conditions were characterized and quantified. • Nine compounds were potentially odorous: TMA, NH3, 2-pentanone, 1-propanol-2-methyl, acetophenone and sulphur forms. • The tested composting process conditions reduced odour emissions by a factor of 5–10. • A reduction of 105 to 106 is required to reach an odour threshold limit at peak event emissions. • Both aeration rate and bulking agent had the most impact on reducing odour emissions. - Abstract: Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forced aeration in 300 L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44 L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10 < 20 and 20 < 30 mm. Out-going gases were sampled every 2 days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC–MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30 days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and bulking agent to

  8. Combination of Successive Alkalinity Producing System (SAPS) and Aeration for Passive Treatment of Highly Acidic Mine Drainage

    Science.gov (United States)

    Oh, C.; Ji, S.

    2015-12-01

    Passive treatment system has been widely used for remediation of mine drainage since its advantage of low installation and maintenance cost. The system, however, has also a disadvantage in assuring remediation and management efficiency if the drainage is highly acidic mine drainage. To remediate acid mine drainage (AMD) especially showing high acidity, passive treatment system which consists of successive alkalinity producing system (SAPS) and subsequent aeration pond was proposed and its mechanisms and efficiency was evaluated in this research. Target AMD was obtained from Waryong coal mine and showed typical characteristics of AMD having high metal concentration and low pH (acidity > 300 mg/L as CaCO3). Four experimental cases were conducted; untreated, treated with SAPS, treated with aeration, treated with SAPS and aeration to compare role and mechanism of each unit. Between organic matter and limestone layer which constitute SAPS, the former eliminated most of Fe(III) and Al in the AMD so that the latter was kept from being clogged by precipitates. Net acidity of the AMD rapidly decreased by supplement of alkalinity at the limestone layer. A primary function of SAPS, producing alkalinity constantly without clogging, was attained due to addition a portion of limestone particle into the organic matter layer. The discharge from SAPS had low ORP and DO values because of an anaerobic environment formed at the organic matter layer although its alkalinity was increased. This water quality was unfavorable for Fe(II) to be oxidized. Installation of aeration pond after SAPS, therefore, could be effective way of enhancing oxidation rate of Fe(II). Among the experimental cases, the combination of SAPS and aeration pond was only able to remediate the AMD. This concluded that to remediate highly acidic mine drainage with passive treatment system, three critical conditions were required; pre-precipitation of Fe(III) and Al at organic matter layer in SAPS, constant alkalinity

  9. Odorous gaseous emissions as influence by process condition for the forced aeration composting of pig slaughterhouse sludge

    Energy Technology Data Exchange (ETDEWEB)

    Blazy, V., E-mail: vincent.blazy@irstea.fr [Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes (France); Guardia, A. de, E-mail: amaury.de-guardia@irstea.fr [Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes (France); Benoist, J.C; Daumoin, M. [Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes (France); Lemasle, M.; Wolbert, D. [Laboratoire Sciences Chimiques de Rennes - équipe Chimie et Ingénierie des Procédés, UMR 6226 CNRS, ENSCR, Avenue du Général Leclerc, 35700 Rennes (France); Barrington, S., E-mail: suzellebarrington@sympatico.ca [Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes (France); Concordia University, Department of Building, Civil and Environmental Engineering, 1455 de Maisonneuve, Montréal, QC H3G 1M8 (Canada)

    2014-07-15

    Highlights: • The gaseous emissions produced by various composting process conditions were characterized and quantified. • Nine compounds were potentially odorous: TMA, NH{sub 3}, 2-pentanone, 1-propanol-2-methyl, acetophenone and sulphur forms. • The tested composting process conditions reduced odour emissions by a factor of 5–10. • A reduction of 10{sup 5} to 10{sup 6} is required to reach an odour threshold limit at peak event emissions. • Both aeration rate and bulking agent had the most impact on reducing odour emissions. - Abstract: Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forced aeration in 300 L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44 L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10 < 20 and 20 < 30 mm. Out-going gases were sampled every 2 days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC–MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30 days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and

  10. 封闭循环水养殖中曝气系统设计及曝气器的选择%Aeration system design and aeration devices selection in Recirculating Aquaculture System

    Institute of Scientific and Technical Information of China (English)

    宋奔奔; 吴凡; 倪琦; 张宇雷; 庄保陆

    2011-01-01

    随着水产养殖业逐渐向高密度、集约化方向的发展,对养殖水体溶解氧浓度的要求越来越高.目前对循环水高密度养殖水体中溶解氧收支平衡的基础研究较少.如何提高氧气的溶解效率、减少氧气的逸出、合理控制溶解氧水平等技术难关的突破,对循环水养殖技术的提高具有重大的意义.本文旨在通过阐述曝气技术的设计理论基础以及曝气设备的最近发展状况,比较各式曝气器的性能参数,从而为封闭循环水养殖曝气系统的设计和曝气器的选择提供理论支持,推动封闭式循环水养殖向精准化的环保节能方向发展.%Dissolved oxygen in water body plays an important role in recirculating aquaculture while developing to higher density and intensification. At present, it' s studied not so much about dissolved oxygen budget and mass balance in intensive recirculating aquaculture system. These problems such as how to improve oxygen dissolving efficiency, decrease oxygen loss and control dissolved oxygen in appropriate level are growing more prominent in recirculating aquaculture system technology. Aeration theory and designing principles, aeration devices characteristics are illustrated and elaborated in this paper to improve the design of recirculating aquaculture aeration system and the selecting of aeration devices, promoting recirculating aquaculture system technology to more environment-friendly and energy conservation.

  11. 加气混凝土墙面抹灰防开裂分析与措施%Aerated concrete wall plastering cracks resistance analysis and measures

    Institute of Scientific and Technical Information of China (English)

    辛志成

    2011-01-01

    Taking actual engineering as the research background,it briefly introduces aerated concrete masonry,analyzes aerated concrete wall plastering cracking causes,and puts forward aerated concrete cracks processing measures,with a view to guarantee the smoothness and integrity of aerated concrete internal and external wall.%以某实际工程为研究背景,对加气混凝土砌块作了简单介绍,分析了加气混凝土墙面抹灰层开裂原因,并提出了加气混凝土开裂处理措施,以期保证加气混凝土内、外墙面上抹灰的平整度、整体性。

  12. AN EXPERIMENTAL INVESTIGATION OF PRESSURE AND CAVITATION CHARACTERISTICS OF HIGH VELOCITY FLOW OVER A CYLINDRICAL PROTRUSION IN THE PRESENCE AND ABSENCE OF AERATION

    Institute of Scientific and Technical Information of China (English)

    DONG Zhi-yong; LIU Zhi-ping; WU Yi-hong; ZHANG Dong

    2008-01-01

    This article experimentally investigated the pressure and cavitation characteristics of high velocity flow over a surface irregularity with and without aeration in a non-circulating water tunnel system. The surface irregularity is a cylindrical protrusion made of stainless steel of 6 mm diameter and 2 mm height. Pressures with and without aeration were measured with MPX400D pressure transducers and real-timely acquired by a SINOCERA YE6263 data acquisition system. Variations in flow regimes with and without aeration were observed. Pressure profiles and their variations with air concentration upper and lower cylindrical protrusion on the invert and obvert walls were determined. Variations of cavitation number with air concentration lower cylindrical protrusion were analyzed. Also, cavitation numbers in the presence and absence of aeration were compared.

  13. Potential of aeration flow rate and bio-char addition to reduce greenhouse gas and ammonia emissions during manure composting

    DEFF Research Database (Denmark)

    Chowdhury, Md Albarune; de Neergaard, Andreas; Jensen, Lars Stoumann

    2014-01-01

    Aeration is an important factor influencing CO2, CH4, N2O and NH3 emissions from the composting process. Both CH4 and N2O are potent greenhouse gases (GHG) of high importance. Here, we examined the effects of high and low aeration rates together with addition of barley straw with and without bio...... composting hen manure and barley straw at low flow rates proved most effective in reducing cumulative NH3 and CH4 losses. Addition of bio-char in combination with barley straw to hen manure at both high and low flow rates reduced total GHG emissions (as CO2-equivalents) by 27-32% compared with barley straw...

  14. Effects of the soil aeration on nutrient absorption, 14C-assimilates distribution and storage root yield in sweet potato

    International Nuclear Information System (INIS)

    Using Ipomoea batatas (L.) Lam. cv Lushu7 and Xushu18 as materials, the effect of the soil aeration on mineral nutrition absorption, 14C-assimilates distribution in storage roots and storage root yield were studied. The results showed that the improved soil aeration could increase the content of potassium, calcium, manganese, boron and zinc in leaves, increase the content of potassium and calcium in storage roots, decrease the content of manganese, boron and zinc in storage roots, improve the transportation of 14C-assimilates, increase the starch content of storage roots and significantly increase the storage root yield. The role of mineral elements on improving the transportation of 14C-assimilates was discussed

  15. Effect of aeration and dilution on continuous bio ethanol production in a packed-bed bioreactor by Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Stability of cell growth was achieved continuously at a steady state in a packed-bed bioreactor. The highest productivity of ethanol was achieved (0.02 g/ L/ h) when 0.003 vvm was employed. The productivity of bio ethanol increases when dilution rate increases. The highest production of 0.037 g/ L/ h was recorded when the dilution rate (D) was at 0.05 per hour. The production of bio ethanol was successfully maintained in a non 100 b % anaerobic condition. The best aeration for the continuous production of bio ethanol in a condition of steady state growth was at an aeration rate of 0.003 vvm. (author)

  16. [Detection of anaerobic processes and microorganisms in immobilized activated sludge of a wastewater treatment plant with intense aeration].

    Science.gov (United States)

    Litti, Iu V; Nekrasova, V K; Kulikov, N I; Siman'kova, M V; Nozhevnikova, A N

    2013-01-01

    Attached activated sludge from the Krasnaya Polyana (Sochi) wastewater treatment plant was studied after the reconstruction by increased aeration and water recycle, as well as by the installation of a bristle carrier for activated sludge immobilization. The activated sludge biofilms developing under conditions of intense aeration were shown to contain both aerobic and anaerobic microorganisms. Activity of a strictly anaerobic methanogenic community was revealed, which degraded organic compounds to methane, further oxidized by aerobic methanotrophs. Volatile fatty acids, the intermediates of anaerobic degradation of complex organic compounds, were used by both aerobic and anaerobic microorganisms. Anaerobic oxidation of ammonium with nitrite (anammox) and the presence of obligate anammox bacteria were revealed in attached activated sludge biofilms. Simultaneous aerobic and anaerobic degradation of organic contaminants by attached activated sludge provides for high rates of water treatment, stability of the activated sludge under variable environmental conditions, and decreased excess sludge formation. PMID:25509405

  17. Selection of optimum conditions of medium acidity and aeration for submerget cultivation of Bacillus thuringiensis and Beauveria bassiana

    Directory of Open Access Journals (Sweden)

    O. A. Dregval

    2010-06-01

    Full Text Available The paper deals with the influence of medium pH and aeration rate on growth and sporulation of Bacillus thuringiensis and Вeauveria bassiana, which are main constituents of the complex microbial insecticide. It was established optimal medium pH for B. thuringiensis – 6.0 and for В. bassiana – 6.0–7.0. The maximum productivity of the studied microorganisms was observed in the same range of aeration – 7– 14 mmol O2/l/h. The selected conditions of cultivation are necessary for the production of complex biological insecticide based on the association of B. thuringiensis and B. bassiana.

  18. Nitrogen removal from on-site treated anaerobic effluents using intermittently aerated moving bed biofilm reactors at low temperature.

    Science.gov (United States)

    Luostarinen, Sari; Luste, Sami; Valentín, Lara; Rintala, Jukka

    2006-05-01

    On-site post-treatment of anaerobically pre-treated dairy parlour wastewater (DPWWe; 10 degrees C) and mixture of kitchen waste and black water (BWKWe; 20 degrees C) was studied in moving bed biofilm reactors (MBBR). The focus was on removal of nitrogen and of residual chemical oxygen demand (COD). Moreover, the effect of intermittent aeration and continuous vs. sequencing batch operation was studied. All MBBRs removed 50-60% of nitrogen and 40-70% of total COD (CODt). Complete nitrification was achieved, but denitrification was restricted by lack of carbon. Nitrogen removal was achieved in a single reactor by applying intermittent aeration. Continuous and sequencing batch operation provided similar nitrogen and COD removal, wherefore simpler continuous feeding may be preferred for on-site applications. Combination of pre-treating upflow anaerobic sludge blanket (UASB) -septic tank and MBBR removed over 92% of CODt, 99% of biological oxygen demand (BOD7), and 65-70% of nitrogen. PMID:16647521

  19. Performance analysis of a pilot-scale membrane aerated biofilm reactor for the treatment of landfill leachate

    OpenAIRE

    Syron, Eoin; Semmens, Michael J.; CASEY, Eoin

    2015-01-01

    A 60 L membrane aerated biofilm reactor (MABR) was successfully employed to treat landfill leachate, which contained very high concentrations of refractory chemical oxygen demand (COD) and ammonium. Air or pure oxygen was supplied to the bioreactor through polydimethyl siloxane hollow fibre membranes. Over a year of operation with an average hydraulic retention time of about 5 days, and influent ammonium concentrations ranging from 500 to 2500 mg/L, the MABR achieved 80–99% nitrification. Sim...

  20. Plasma levels of sRAGE, loss of aeration and weaning failure in ICU patients: a prospective observational multicenter study.

    Directory of Open Access Journals (Sweden)

    Matthieu Jabaudon

    Full Text Available RATIONALE: Postextubation distress after a successful spontaneous breathing trial (SBT is associated with increased morbidity and mortality. Lung ultrasound determination of changes in lung aeration predicts weaning failure. It remains unknown whether this derecruitment is related to alveolar epithelial dysfunction or not. OBJECTIVE: To verify whether lung alveolar type I epithelial cell injury marker sRAGE (soluble form of the receptor for advanced glycation end-products is predictive of postextubation distress and weaning failure or not, and to verify whether plasma sRAGE levels can be related to lung derecruitment during the process of weaning from mechanical ventilation or not. INTERVENTIONS MEASUREMENTS: 88 patients from 2 intensive care units were included in this observational prospective study. Plasma sRAGE levels were measured in duplicate by ELISA before, at the end of a 60-minute SBT, and 4 hours after extubation. To quantify lung aeration, a lung ultrasound score was calculated. MAIN RESULTS: 34% of extubated patients experienced postextubation distress. Patients with or without postextubation distress had comparable sRAGE levels before SBT, after SBT, and 4 hours after extubation. In patients with postextubation distress, sRAGE levels were not predictive of the need for mechanical ventilation. sRAGE levels were not associated with lung aeration as assessed by echography. Patients who succeeded SBT (86% and those who failed (14% had no differences in sRAGE levels, before (median 1111 vs 1021 pg/mL, p = 0,87 and at the end of SBT (1165 vs 1038 pg/mL, p = 0.74. CONCLUSIONS: Plasma levels of sRAGE do not predict postextubation distress or SBT failure/success in patients weaning from mechanical ventilation. Lung aeration loss during a successful weaning trial predicts postextubation distress, but may not be evaluable by plasma levels of sRAGE, a marker of alveolar type I epithelial cell injury. TRIAL REGISTRATION: Clinical

  1. INFLUENCE OF SODIUM GLUTAMATE, BUBBLING N2- GAS AND SUPERFICIAL AERATION ON TETANUS TOXIN PRODUCTION IN Clostridium tetani CULTURES

    OpenAIRE

    Gutiérrez, I.; Garzón, E.; Vargas, P.; Moreno, N.; R. Poutou

    2005-01-01

    The influence of sodium glutamate as a supplement to Latham Mueller medium, while using bubbling nitrogen flow as an anaerobic agent and superficial aeration as an inducer of cell lysis and as a mechanism for the haulage of gases in the fermentation processes was evaluated. Using the Clostridium tetani Massachusetts’s strain, several five (5) liter batch fermentations were carried out for tetanus toxin production under the following conditions: Latham Mueller medium, with or without sodium gl...

  2. Method of aeration disinfecting and drying grain in bulk and pretreating seeds and a transverse blow silo grain dryer therefor

    Science.gov (United States)

    Danchenko, Vitaliy G.; Noyes, Ronald T.; Potapovych, Larysa P.

    2012-02-28

    Aeration drying and disinfecting grain crops in bulk and pretreating seeds includes passing through a bulk of grain crops and seeds disinfecting and drying agents including an ozone and air mixture and surrounding air, subdividing the disinfecting and drying agents into a plurality of streams spaced from one another in a vertical direction, and passing the streams at different heights through levels located at corresponding heights of the bulk of grain crops and seeds transversely in a substantially horizontal direction.

  3. STUDY ON APPLICATION OF AERATION BIOLOGICAL FLUID TANK TECHNOLGY IN NH4+—N WASTE WATER TREATMENT

    Institute of Scientific and Technical Information of China (English)

    CHENYi; LUJian-guo

    2003-01-01

    This paper introduces an application of "Aeration biological fluid tank"technology (ABFT) for the treatment of waste water containing NH4+-N and high concentrated chemicals.Highlights were focused on the effects of dissolved oxygen,pH,temperature and retention time on waste water bilogical treatment in order to find out a new approach in treatment of waste time on containing high concentrated NH4+-N.

  4. Treatment of High-Strength Nitrogen Wasetewater With a Hollow-Fiber Membrane-Aerated Biofilm Reactor: A Comprehensive Evaluation

    OpenAIRE

    Gilmore, Kevin R

    2008-01-01

    Protecting the quality and quantity of our water resources requires advanced treatment technologies capable of removing nutrients from wastewater. This research work investigated the capability of one such technology, a hollow-fiber membrane-aerated biofilm reactor (HFMBR), to achieve completely autotrophic nitrogen removal from a wastewater with high nitrogen content. Because the extent of oxygenation is a key parameter for controlling the metabolic processes that occur in a wastewate...

  5. Feasibility study of an aeration treatment system in a raw water storage reservoir used as a potable water source

    OpenAIRE

    Fronk, Robert Charles

    1996-01-01

    The systems engineering process has been utilized to determine the feasibility of an aeration treatment system for a raw water storage reservoir used as a potable water source. This system will be used to ensure a consistently high quality of raw water by the addition of dissolved oxygen into the reservoir. A needs analysis establishes the importance and requirements for a consistently high quality of raw water used as a source for a potable water treatment facility. This s...

  6. Experimental Determination of Mechanical Properties of Autoclaved Aerated Concrete Masonry with Vertical Hollows Confined with Disperse Rein-Forced Concrete

    OpenAIRE

    Iernuţan, Răzvan-Andrei; Roman-Pintican, Maria-Nicoleta

    2014-01-01

    The present paper aims at finding solutions alternative to the conventionally reinforced masonry, namely by replacing the confination with reinforced concrete columns and girders with vertical and horizontal hollows in the autoclaved aerated concrete (AAC) masonry. The voids are filled with disperse steel fibre reinforced concrete. The use of the disperse reinforced concrete in structural masonry walls, in low seismic areas, is seen to allow the replacement of confined or reinforced con...

  7. Effect of Post-Infiltration Soil Aeration at Different Growth Stages on Growth and Fruit Quality of Drip-Irrigated Potted Tomato Plants (Solanum lycopersicum.

    Directory of Open Access Journals (Sweden)

    Yuan Li

    Full Text Available Soil hydraulic principles suggest that post-infiltration hypoxic conditions would be induced in the plant root-zone for drip-irrigated tomato production in small pots filled with natural soil. No previous study specifically examined the response of tomato plants (Solanum lycopersicum at different growth stages to low soil aeration under these conditions. A 2 × 6 factorial experiment was conducted to quantify effects of no post-infiltration soil aeration versus aeration during 5 different periods (namely 27-33, 34-57, 58-85, 86-99, and 27-99 days after sowing, on growth and fruit quality of potted single tomato plants that were sub-surface trickle-irrigated every 2 days at 2 levels. Soil was aerated by injecting 2.5 liters of air into each pot through the drip tubing immediately after irrigation. Results showed that post-infiltration aeration, especially during the fruit setting (34-57 DAS and enlargement (58-85 DAS growth stages, can positively influence the yield, root dry weight and activity, and the nutritional (soluble solids and vitamin C content, taste (titratable acidity, and market quality (shape and firmness of the tomato fruits. Interactions between irrigation level and post-infiltration aeration on some of these fruit quality parameters indicated a need for further study on the dynamic interplay of air and water in the root zone of the plants under the conditions of this experiment.

  8. Targeted modification of organic components of municipal solid waste by short-term pre-aeration and its enhancement on anaerobic degradation in simulated landfill bioreactors.

    Science.gov (United States)

    Ni, Zhe; Liu, Jianguo; Girotto, Francesca; Cossu, Raffaello; Qi, Guangxia

    2016-09-01

    Pre-aeration is effective on regulating subsequent anaerobic degradation of municipal solid waste (MSW) with high organic fractions during landfilling. The strength of pre-aeration should be optimized to intentionally remove some easily biodegradable fractions while conserve bio-methane potential as much as possible. This study investigates the evolution of organic components in MSW during 2-14days pre-aeration process and its impacts on subsequent anaerobic degradation in simulated landfill bioreactors. Results showed that a 6-day pre-aeration enabled to develop a thermophilic stage, which significantly accelerated biodegradation of organics except lignocelluloses, with removal rates of 42.8%, 76.7% and 25.1% for proteins, carbohydrates and lipids, respectively. Particularly, ammonia from accelerated ammonification in the thermophilic stage neutralized VFAs generated from anaerobic landfilling. As a result, the MSW with 6-day pre-aeration obtained the highest methane yield 123.4NL/kg dry matter. Therefore, it is recommended to interrupt pre-aeration before its cooling stage to switch to anaerobic landfilling. PMID:27243602

  9. 污水处理厂微孔曝气器选型的探讨%Discussion of Selecting Microporous Aerator in Sewage Treatment Plant

    Institute of Scientific and Technical Information of China (English)

    周鹏飞

    2013-01-01

    Aerator is the core equipment of sewage treatment plant. Current prevalent microporous aeration is an effective and energy-saving aeration mode. It's very important to select feasible microporous aerator. It should not only ensure stable operation and low cost, but also save equipment investment and maintenance costs. Based on the application effect in sewage treatment plant, analyzed characteristics, merits and advantages of several microposous aerators and discussed the selection of microporous aerators.%曝气器是污水处理厂的核心设备.目前广泛运用的鼓风机微孔曝气是一种高效节能的曝气方式.选择适当的微孔曝气器是非常重要的,不仅保障污水处理效果稳定,运行成本较低,还能节省设备投资和维护费用.结合微孔曝气器在污水处理厂的运用效果,分析了各种微孔曝气器的性能、特点和优劣,并对污水处理厂微孔曝气器的选型进行了探讨.

  10. Positive effect of reduced aeration rate on growth and stereospecificity of DL-malic acid consumption by Azospirillum brasilense: improving the shelf life of a liquid inoculant formulation.

    Science.gov (United States)

    Carrasco-Espinosa, Karen; García-Cabrera, Ramsés I; Bedoya-López, Andrea; Trujillo-Roldán, Mauricio A; Valdez-Cruz, Norma A

    2015-02-10

    Azospirillum brasilense has significance as a growth promoter in plants of commercial interest. Two industrial native strains (Start and Calf), used as a part of an inoculant formulation in Mexico during the last 15 years, were incubated in laboratory-scale pneumatic bioreactors at different aeration rates. In both strains, the positive effect of decreased aeration was observed. At the lowest (0.1 vvm, air volume/liquid volume×minute), the highest biomass were obtained for Calf (7.8 × 10(10)CFU/ml), and Start (2.9 × 10(9)CFU/ml). These were higher in one magnitude order compared to cultures carried out at 0.5 vvm, and two compared to those at 1.0 vvm. At lower aeration, both stereoisomeric forms of malic acid were consumed, but at higher aeration, just L-malate was consumed. A reduction in aeration allows an increase of the shelf life and the microorganism saved higher concentrations of polyhydroxybutyrate. The selected fermentation conditions are closely related to those prevalent in large-scale bioreactors and offer the possibility of achieving high biomass titles with high shelf life at a reduced costs, due to the complete use of a carbon source at low aeration of a low cost raw material as DL-malic acid mixture in comparison with the L-malic acid stereoisomer. PMID:25556026

  11. Control of Grifola frondosa Morphology by Agitation and Aeration for Improving Mycelia and Exo-Polymer Production.

    Science.gov (United States)

    Cui, Feng-Jie; Chen, Xiao-Xiao; Liu, Wei-Min; Sun, Wen-Jing; Huo, Shuhao; Yang, Yan

    2016-06-01

    The present study describes the improved mycelia and exo-polymer production under control of Grifola frondosa morphology by changing the aeration rate and agitation intensity in a 25-L stirred fermentor. The aeration rate of 1.0 vvm yielded a highest mycelia biomass of 24.754 g/L with the lowest pellet percentage of 20.5 %. The maximum exo-polymer (2.324 g/L) was achieved at 0.75 vvm with mycelia polysaccharide production (0.321 g/g), whereas clumps and filaments dominated the ratios of 45.6 and 33.9 %, respectively. The change of aeration rate and agitation intensity had slight influence on the monosaccharide compositions in exo-polymers and significantly affected glucose and mannose contents in the mycelia polysaccharides. These findings will provide a clue for exploring the relationship between fermentation parameters, morphologies, and polysaccharide synthesis pathway of G. frondosa. PMID:26861733

  12. Pollutants removal in subsurface infiltration systems by shunt distributing wastewater with/without intermittent aeration under different shunt ratios.

    Science.gov (United States)

    Pan, Jing; Yuan, Fang; Zhang, Yang; Huang, Linli; Yu, Long; Zheng, Fanping; Cheng, Fan; Zhang, Jiadi

    2016-10-01

    Matrix dissolved oxygen (DO), removal of COD, TP and nitrogen in subsurface infiltration systems (SISs), named SIS A (without intermittent aeration and shunt distributing wastewater), SIS B (with shunt distributing wastewater) and SIS C (with intermittent aeration and shunt distributing wastewater) were investigated. Aerobic conditions were developed in 50cm depth and anoxic or anaerobic conditions were not changed in 80 and 110cm depth by intermittent aeration. Under appropriate shunt ratios, shunt distributing wastewater improved denitrification and had little influence on COD, TP and NH3-N removal. Under the optimal shunt ratio of 1:2 for SIS C, high average removal rates of COD (90.06%), TP (93.17%), NH3-N (88.20%) and TN (85.79%) were obtained, which were higher than those in SIS A (COD: 82.56%, TP: 92.76%, NH3-N: 71.08%, TN: 49.24%) and SIS B (COD: 81.12%, TP: 92.58%, NH3-N: 69.14%, TN: 58.73%) under the optimal shunt ratio of 1:3. PMID:27347804

  13. Aerobic N2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process.

    Science.gov (United States)

    Wang, Huoqing; Guan, Yuntao; Pan, Min; Wu, Guangxue

    2016-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas that can be emitted during biological nitrogen removal. N2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600mL/min sequencing batch reactor (SBRL) and 1200mL/min (SBRH). The nitrogen removal percentage was 89% in SBRL and 71% in SBRH, respectively. N2O emission mainly occurred during the aerobic phase, and the N2O emission factor was 10.1% in SBRL and 2.3% in SBRH, respectively. In all batch experiments, the N2O emission potential was high in SBRL compared with SBRH. In SBRL, with increasing aeration rates, the N2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification (SND). By contrast, in SBRH the N2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N2O emission during biological nitrogen removal. PMID:27155411

  14. Treatment of petrochemical secondary effluent by an up-flow biological aerated filter (BAF).

    Science.gov (United States)

    Fu, L Y; Wu, C Y; Zhou, Y X; Zuo, J E; Ding, Y

    2016-01-01

    In this study, petrochemical secondary effluent was treated by a 55 cm diameter pilot-scale biological aerated filter (BAF) with a media depth of 220 cm. Volcanic rock grains were filled as the BAF media. Median removal efficiency of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) was 29.35 and 57.98%, respectively. Moreover, the removal profile of the COD, NH3-N, total nitrogen and total organic carbon demonstrated that the filter height of 140 cm made up to 90% of the total removal efficiency of the final effluent. By gas chromatography-mass spectrometry, removal efficiencies of 2-chloromethyl-1,3-dioxolane, and benzonitrile, indene and naphthalene were obtained, ranging from 30.12 to 63.01%. The biomass and microbial activity of the microorganisms on the filter media were in general reduced with increasing filter height, which is consistent with the removal profile of the contaminants. The detected genera Defluviicoccus, Betaproteobacteria_unclassified and the Blastocatella constituted 1.86-6.75% of the identified gene, enhancing the COD and nitrogen removal in BAF for treating petrochemical secondary effluent. PMID:27120658

  15. Characterization of soluble microbial products in a drinking water biological aerated filter.

    Science.gov (United States)

    Kang, Jia; Ma, Teng-Fei; Zhang, Peng; Gao, Xu; Chen, You-Peng

    2016-05-01

    Utilization-associated products (UAPs) and biomass-associated products (BAPs) were quantified separately in this study to characterize soluble microbial products (SMPs) in a drinking water lab-scale biological aerated filter (BAF), and their basic characteristics were explored using gel filtration chromatography and three-dimensional excitation-emission matrix (3D-EEM) spectrophotometry with fluorescence regional integration analysis and parallel factor model. UAPs were observed increased with the increase of filter media depth and accumulated after BAF treatment, whereas BAPs were basically constant. 3D-EEM spectroscopy analysis result showed that tryptophan and protein-like compounds were the main components of UAPs and BAPs, and fulvic-acid-like substance was a major component of BAPs, rather than UAPs. In terms of molecular weight (MW) distribution, UAP MW presented a bimodal distribution in the range of 1-5 and >10 kDa, while BAP MW exhibited unimodal distribution with MW >20 kDa fraction accounting for more than 90 %. The macromolecules of UAPs accumulated after BAF treatment. This study provides theoretical support for in-depth study of SMP characteristics. PMID:26801929

  16. Passivity and passivity breakdown of a zinc electrode in aerated neutral sodium nitrate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Amin, Mohammed A. [Chemistry Department, Faculty of Science, Ain Shams University, 11566 Abbassia, Cairo (Egypt)]. E-mail: maaismail@yahoo.com

    2005-01-30

    The passivation and pitting corrosion behaviour of a zinc electrode in aerated neutral sodium nitrate solutions was investigated by cyclic voltammetry and chronopotentiometry techniques, complemented by ex situ scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) examinations of the electrode surface. Measurements were conducted under different experimental conditions. The potentiodynamic anodic polarization curves do not exhibit active dissolution region due to spontaneous passivation. The passivity is due to the presence of thin film of ZnO on the anode surface. The passive region is followed by pitting corrosion as a result of breakdown of the passive film. SEM images confirmed the existence of pits on the electrode surface. The breakdown potential decreases with an increase in NO{sub 3}{sup -} concentration and temperature, but increases with increasing potential scan rate. Addition of SO{sub 4}{sup 2-} ions to the nitrate solution accelerates pitting corrosion, while addition of WO{sub 4}{sup 2-} and MoO{sub 4}{sup 2-} ions inhibits pitting corrosion. The chronopotentiometry measurements show that the incubation time for pitting initiation decreases with increasing NO{sub 3}{sup -} concentration, temperature and applied anodic current density. Addition of SO{sub 4}{sup 2-} ions decreases the rate of passive film growth and the incubation time, while the reverse changes produced by addition of either WO{sub 4}{sup 2-} or MoO{sub 4}{sup 2-} ions.

  17. Passivity and passivity breakdown of a zinc electrode in aerated neutral sodium nitrate solutions

    International Nuclear Information System (INIS)

    The passivation and pitting corrosion behaviour of a zinc electrode in aerated neutral sodium nitrate solutions was investigated by cyclic voltammetry and chronopotentiometry techniques, complemented by ex situ scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) examinations of the electrode surface. Measurements were conducted under different experimental conditions. The potentiodynamic anodic polarization curves do not exhibit active dissolution region due to spontaneous passivation. The passivity is due to the presence of thin film of ZnO on the anode surface. The passive region is followed by pitting corrosion as a result of breakdown of the passive film. SEM images confirmed the existence of pits on the electrode surface. The breakdown potential decreases with an increase in NO3- concentration and temperature, but increases with increasing potential scan rate. Addition of SO42- ions to the nitrate solution accelerates pitting corrosion, while addition of WO42- and MoO42- ions inhibits pitting corrosion. The chronopotentiometry measurements show that the incubation time for pitting initiation decreases with increasing NO3- concentration, temperature and applied anodic current density. Addition of SO42- ions decreases the rate of passive film growth and the incubation time, while the reverse changes produced by addition of either WO42- or MoO42- ions

  18. Gamma radiolytic decomposition of endosulfan in aerated solution: the role of carbonate radical.

    Science.gov (United States)

    Shah, Noor S; Khan, Javed Ali; Al-Muhtaseb, Ala'a H; Sayed, Murtaza; Khan, Hasan M

    2016-06-01

    The present study elaborates the removal of endosulfan, an emerging water pollutant and potential carcinogenic, in aerated solution. The influence of Cl(-), NO3 (-), NO2 (-), CO3 (2-), HCO3 (-), SO3 (2-), and humic acid was assessed on the radiolytic degradation of endosulfan. A strong inhibition on the radiolytic degradation of endosulfan was observed in the presence of NO3 (-), NO2 (-), and SO3 (2-). Instead, a slight increase in the removal efficiency of endosulfan was observed at high concentrations of CO3 (2-) and HCO3 (-). The formation of CO3 (•-) in radiolytic degradation of endosulfan in the presence of CO3 (2-) and HCO3 (-) was demonstrated by adding SO3 (2-) that rapidly react with CO3 (•-). The results indicate that CO3 (•-) formed from the reactions of CO3 (2-) and HCO3 (-) and commonly found in natural water can play an important role in the degradation of endosulfan and other sulfur containing electron-rich compounds. The study showed faster degradation of endosulfan at lower concentration compared to high concentration and removal was found to follow pseudo-first-order kinetic. Endosulfan ether was found as the main degradation product and degradation pathway was found to be initiated at the S=O bond of endosulfan. The efficiency of gamma irradiation in the removal of endosulfan was examined in terms of formation of short chain organic acids and chloride ion accumulation. PMID:26979317

  19. Textile effluent treatment in a UASB reactor followed by submerged aerated biofiltration.

    Science.gov (United States)

    Ferraz, A D N; Kato, M T; Florencio, L; Gavazza, S

    2011-01-01

    An upflow anaerobic sludge bed (UASB)-submerged aerated biofilter (SAB) system that treats effluents from a jeans factory was evaluated. The 210-day operational period was divided into three phases (PI, PII and PIII), each with a different hydraulic retention time (HRT in h) and organic loading rate (OLR in kg COD/m3.d). In PI, the best performance was achieved using the UASB (HRT 24, OLR 1.3) with COD and color removal efficiencies of 59 and 64%, respectively; the corresponding values were 77 and 86% for the final effluent. In PII, the efficiencies were 50 and 55% using the UASB (HRT 16, OLR 1.2), respectively, and 69 and 81% for the final system effluent, respectively. In PIII, the UASB (HRT 12 and ORL 3.2) showed the poorest performance; the efficiencies decreased to 48 and 50%, respectively. The same phenomenon occurred in the system with corresponding efficiencies decreasing to 69 and 61%. Throughout the experiment, the system removal efficiencies were between 57 and 88% for nitrogen and between 14 and 63% for sulfate. The final effluent showed relatively non-toxicity or moderate toxicity using Daphnia magna as an indicator. Therefore, the overall results showed that the use of a sequential anaerobic-aerobic system is promising for treatment of textile industrial wastewater. PMID:22335099

  20. Nasolacrimal system aeration on computed tomographic imaging: effects of patient positioning and scan orientation

    Directory of Open Access Journals (Sweden)

    Czyz CN

    2015-03-01

    Full Text Available Craig N Czyz,1 Thomas S Bacon,2 Andrew W Stacey,3 Eva N Cahill,4 Bryan R Costin,5 Boris I Karanfilov,6 Kenneth V Cahill5 1Section Oculofacial Plastic and Reconstructive Surgery, Ohio University/OhioHealth, 2Department of Medical Education, Mount Carmel Health Systems, Columbus, OH, USA; 3Department of Ophthalmology, University of Michigan, Ann Arbor, MI, USA; 4Department of Biology, Wittenberg University, Springfield, OH, USA; 5Department of Ophthalmology, William H Havener Eye Institute, Ohio State University Wexner Medical Center, Columbus, OH, USA; 6The Sinus Institute of Ohio, Dublin, OH, USA Purpose: To determine the impact of patient positioning and scan orientation on the appearance of air in the nasolacrimal drainage system on computed tomography (CT imaging, and the repeatability of the observations.Methods: This was a retrospective analysis of CT images for 92 patients.Results: Air was found to be present more fully in the upright-position group as compared with the supine-position group. Comparing axial and coronal scan orientation, no difference in aeration was found, except for the nasolacrimal duct in the upright-position group.Conclusion: Patient position should be accounted for in diagnostic conclusions and treatment decisions based on CT. Keywords: axial, coronal, nasolacrimal sac, nasolacrimal duct

  1. Turbulence, aeration and bubble features of air-water flows over macro- and intermediate roughness

    Directory of Open Access Journals (Sweden)

    Stefano PAGLIARA

    2011-06-01

    Full Text Available Free surface flows in macro- and intermediate roughness conditions have a high aeration potential in which the flow characteristics vary with slopes and discharges. The underlying phenomenon of two phase flow characteristics in the macro and intermediate roughness conditions were analyzed in a setup assembled at the PITLAB center of the University of Pisa, Italy. Crushed angular rocks and hemispherical boulders were used to intensify the roughness nature of the bed. Flow discharges per unit width ranging between 0.03 m2/s and 0.09 m2/s and slopes between 0.26 and 0.46 were tested over different arrangements of rough bed. Analyses were mainly concentrated in the inner flow region which constitutes both bubbly and intermediate flow region. The findings revealed that two phase flow properties over rough bed were very much affected by the different rough bed arrangement. Turbulence features of two phase flows over rough beds were compared with that of the stepped chute data under similar flow conditions. Overall the results highlighted the flow features in the inner layers of the two phase flow.

  2. Thermodynamic and kinetics for synergistic aeration adsorption uranium (VI) on banyan leaves-activated sludge

    International Nuclear Information System (INIS)

    Synergistic aeration adsorption of uranium from aqueous solution using banyan leaves (BL) and activated sludge (AS) was investigated by thermodynamic and kinetics batch experiments in the temperature range of 20-50 degree C. The results show that the adsorption ratio of U (VI) with the initial concentration of 100 mg/L on BL-AS is more than 99%, and the maximal adsorption capacity is 13.055 mg/g for 60 min, at pH=3.0 and 20 degree C. Pseudo 2nd-order model best describes the reaction kinetics; the adsorption capacity calculated by the model is consistent with that actual measured (r2>0.99). The experimental data better follow Freundlich isotherm model and Langmuir isotherm model at 20 degree C (r2>0.98). For the whole adsorption process, the enthalpy change is-45.2 kJ/mol, the entropy change is-46.2 J/(mol · K), and the Gibbs free energy chang is-31.7(20 degree C), -31.2(30 degree C), -30.7(40 degree C), -30.3(50 degree C) kJ/mol respectively, which indicates that the process is spontaneous, radiative, irreversible and physical adsorption process. (authors)

  3. Comparison of axial vibration membrane and submerged aeration membrane in microalgae harvesting.

    Science.gov (United States)

    Zhao, Fangchao; Chu, Huaqiang; Tan, Xiaobo; Zhang, Yalei; Yang, Libin; Zhou, Xuefei; Zhao, Jianfu

    2016-05-01

    The submerged aeration membrane (SAM) system and axial vibration membrane (AVM) system can mitigate membrane fouling. In this study, both systems were investigated to compare the performance of filtration and the membrane fouling in algae filtration. In 5-h filtration, the transmembrane pressure (TMP) of SAM reached to 70.0kPa, while there was almost no increase in TMP for AVM. After continuous filtration, it could be found that there was hardly any algae cells on the membrane of AVM (0.11g/m(2)), which was about 32.4 times less than that of SAM (3.56g/m(2)). Compared with the SAM system, AVM had a lesser membrane fouling, regardless of the reversible fouling or irreversible fouling. By SEM, FTIR and EEM, it could be found there was less irreversible extracellular organic matter (EOM) on the membrane of AVM. By MW distribution, it could be observed that less EOM with high-MW adhered to membrane of AVM. PMID:26943935

  4. Determination methodology of biomass and Pac at aeration unit in Pact process

    International Nuclear Information System (INIS)

    In this research by using two pilot scale systems of activated sludge and powdered activated carbon technology, the soluble organic load removal efficiency was evaluated, for a synthetic wastewater with mono-ethylen glyco le as carbon source. Also, the variations of biomass and powdered activated carbon in each reactor were studied and the relative accuracy of differential ignition method for determining the amount of biomass and powdered activated carbon (combined in aeration unite of the powdered activated carbon pilot) was investigated. Results showed that the method may be used for the determination of powdered activated carbon and biomass volatility at 400deg C and 550deg C respectively, with acceptable accuracy. Comparison between the results of this study and some other recent studies, show that there is no significant differences between them at 95% confidence. Furthermore, the results of this study indicated that there was little difference in carbon to biomass ration which supports the concept that solid residence time and the amount of wastage sludge can be determined with total suspended solids analysis and there is no necessity for biomass determination

  5. Effect of selective dissolution, electrolytes, aeration, and sterilization on technetium-99 sorption by soils

    International Nuclear Information System (INIS)

    The objective of this study was to determine the extent that technetium 99, a long-lived beta-emitting radionuclide, might be sorbed from aqueous solution by 11 well-characterized soils, and to elucidate the sorption mechanisms involved. About 98% of the added 99Tc was sorbed within a period of 2 to 5 weeks by 8 of the 11 soils. The slow kinetics observed and the removal of trace quantities of 99Tc from solution in the presence of large amounts of chloride and phosphate tend to rule out anion exchange as the sorption mechanism. The lack of sorption exhibited by the low organic matter soils, the reduction in sorption following H2O2 digestion of the soil, and the high recoveries of sorbed 99Tc on extraction with NaOH suggest a role for the living and/or nonliving organic fraction of the soil. Sterilization of previously sorbing soils eliminated the sorption ability, indicating a microbial role in the process. Results of aeration experiments were ambiguous but suggest that anaerobic conditions are not a prerequisite for 99Tc sorption by soils

  6. A study of aeration treatment of uranium-contained wastewater by saccharomyces cerevisiae-activated sludge

    International Nuclear Information System (INIS)

    Experiments of the aeration treatment of uranium-contained wastewater by saccharomyces cerevisiae-activated sludge were carried out. The experimental results indicate that, saccharomyces cerevisiae (S.C) can accumulate UO22+ effectively from aqueous solution: the removal ratio of 100 mg·L-1 UO22+ is 78.2% when S.C dosage is 10 g·L-1, while with 8 g·L-1 activated sludge (A.S.) added in the solution the ratio has increased to 96.3%; then, 5-10 min effluent settling is clarified as a result of sludge flocculation; the optimum conditions of biosorption of U from wastewater by S.C.-A.S. are at pH 5, A.S concentration=8 g·L-1, added dry weight of S.C.=10 g·L-1, granularity of S.C=100-120 mesh; the quantity of U increases with the enhanced initial concentration of UO22+ in the process of biosorption by S.C.-A.S., but the removal ratio decreases. The uptake of U could be described by the Freundlich and the Langmuir adsorption isotherms, which demonstrated that the adsorption was regarded as a physical adsorption. (authors)

  7. Hankel transform of a sequence obtained by series reversion II - aerating transforms

    CERN Document Server

    Bojičić, Radica; Barry, Paul

    2011-01-01

    This paper provides the connection between the Hankel transform and aerating transforms of a given integer sequence. Results obtained are used to establish a completely different Hankel transform evaluation of the series reversion of a certain rational function $Q(x)$ and shifted sequences, recently published in our paper \\cite{part1}. For that purpose, we needed to evaluate the Hankel transforms of the sequences $\\seqn{\\alpha^2 C_n-\\beta C_{n+1}}$ and $\\seqn{\\alpha^2 C_{n+1}-\\beta C_{n+2}}$, where $C=\\seqn{C_n}$ is the well-known sequence of Catalan numbers. This generalizes the results of Cvetkovi\\' c, Rajkovi\\'c and Ivkovi\\'c \\cite{CRI}. Also, we need the evaluation of Hankel-like determinants whose entries are Catalan numbers $C_n$ and which is based on the recent results of Krattenthaler \\cite{krattCat}. The results obtained are general and can be applied to many other Hankel transform evaluations.

  8. Rapid Startup and Loading of an Attached Growth, Simultaneous Nitrification/Denitrification Membrane Aerated Bioreactor

    Science.gov (United States)

    Meyer, Caitlin; Vega, Leticia

    2014-01-01

    The Membrane Aerated Bioreactor (MABR) is an attached-growth biological system for simultaneous nitrification and denitrification. This design is an innovative approach to common terrestrial wastewater treatments for nitrogen and carbon removal. Implementing a biologically-based water treatment system for long-duration human exploration is an attractive, low energy alternative to physiochemical processes. Two obstacles to implementing such a system are (1) the "start-up" duration from inoculation to steady-state operations and (2) the amount of surface area needed for the biological activity to occur. The Advanced Water Recovery Systems (AWRS) team at JSC explored these two issues through two tests; a rapid inoculation study and a wastewater loading study. Results from these tests demonstrate that the duration from inoculation to steady state can be reduced to two weeks and that the surface area to volume ratio baseline used in the Alternative Water Processor (AWP) test was higher than what was needed to remove the organic carbon and ammonium from the system.

  9. Identification of the mechanism limiting the alteration of clad spent fuel segments in aerated carbonated groundwater

    Science.gov (United States)

    Jégou, C.; Peuget, S.; Broudic, V.; Roudil, D.; Deschanels, X.; Bart, J. M.

    2004-03-01

    Leaching experiments were performed with five spent fuel samples (20 mm segments of clad fuel rods) from French power reactors (four UO 2 fuel samples with burnup ratings of 22, 37, 47 and 60 GW d t HM-1 and a MOX fuel sample irradiated to 47 GW d t HM-1) to determine the release kinetics of the matrix containing most of the radionuclides. The experiments were carried out with carbonated groundwater on previously leached sections of clad fuel rods in static mode, in an aerated medium at room temperature (25 °C) in a hot cell. Until 313 days of leaching and below uranium saturation, the Sr/U congruence ratios for all the UO 2 fuel samples ranged from 1 to 2; allowing for the experimental uncertainty, strontium can thus be considered as a satisfactory matrix alteration tracer. No significant burnup effect was observed on the alteration of the UO 2 fuel matrix. The daily strontium release factor was approximately 2.7 × 10 -8 d -1 for UO 2 fuel after 706 days of leaching, and seven to eight times higher for MOX fuel. Several alteration mechanisms (radiolysis, solubility, precipitation/clogging) are examined to account for the experimental findings. All the available experimental data (characterization of secondary phases and leaching data) indicate that the mechanism limiting the spent fuel alteration kinetics, for the conditions studied, is likely based on the transport and accessibility of oxidizing species and/or water within the segment.

  10. Identification of the mechanism limiting the alteration of clad spent fuel segments in aerated carbonated groundwater

    International Nuclear Information System (INIS)

    Leaching experiments were performed with five spent fuel samples (20 mm segments of clad fuel rods) from French power reactors (four UO2 fuel samples with burnup ratings of 22, 37, 47 and 60 GW d tHM-1 and a MOX fuel sample irradiated to 47 GW d tHM-1) to determine the release kinetics of the matrix containing most of the radionuclides. The experiments were carried out with carbonated groundwater on previously leached sections of clad fuel rods in static mode, in an aerated medium at room temperature (25 deg. C) in a hot cell. Until 313 days of leaching and below uranium saturation, the Sr/U congruence ratios for all the UO2 fuel samples ranged from 1 to 2; allowing for the experimental uncertainty, strontium can thus be considered as a satisfactory matrix alteration tracer. No significant burnup effect was observed on the alteration of the UO2 fuel matrix. The daily strontium release factor was approximately 2.7 x 10-8 d-1 for UO2 fuel after 706 days of leaching, and seven to eight times higher for MOX fuel. Several alteration mechanisms (radiolysis, solubility, precipitation/clogging) are examined to account for the experimental findings. All the available experimental data (characterization of secondary phases and leaching data) indicate that the mechanism limiting the spent fuel alteration kinetics, for the conditions studied, is likely based on the transport and accessibility of oxidizing species and/or water within the segment

  11. Strain rate sensitivity of autoclaved aerated concrete from quasi-static regime to shock loading

    Science.gov (United States)

    Mespoulet, Jérôme; Plassard, Fabien; Hereil, Pierre Louis

    2015-09-01

    The quasi-static mechanical behavior of autoclaved aerated concrete is well-known and can be expressed as a function of its density. There are however not much studies dealing with its dynamic behavior and its damping ability when subjected to a mechanical shock or a blast. This study presents experimental results obtained at the Shock Physics Laboratory of THIOT INGENIERIE company. The test specimens are made of YTONG(TM ) cellular concrete with porosity in the range of 75 to 80%. Experimental tests cover a large strain rate amplitude (higher than 104 s-1) for specimens up to 250 mm. They were carried out with a small compression press and with two facilities dedicated to dynamic material characterization: JUPITER dynamic large press (2 MN, 3 ms rising time) and TITAN multi-caliber single-stage gas gun. Results in un-confined conditions show an increase of the compressive strength when strain rate increases (45% increase at 5.102 s-1) but dynamic tests induce damage early in the experiment. This competition between dynamic strength raise and specimen fracture makes the complete compaction curve determination not to be done in unconfined dynamic condition. A 25% increase of the compressive strength has been observed between unconfined and confined condition in Q.S. regime.

  12. Impact of External Heat Insulation on Drying Process of Autoclaved Aerated Concrete Masonry Constructions

    Science.gov (United States)

    Rubene, S.; Vilnitis, M.; Noviks, J.

    2015-11-01

    In the time when sustainable construction as well as cost saving on heating and cooling of buildings is one of the most important construction trends, it is important to acknowledge the possibilities of application of construction materials with high heat insulation parameters and the ways in which these parameters can be obtained. Autoclaved aerated concrete (AAC) is a load bearing construction material, which has high heat insulation parameters, although it has one significant disadvantage. If the AAC masonry construction has high moisture content, it loses its heat insulation properties. This is the reason why it is important to detect the humidity distribution throughout the cross section of the masonry elements in order to conduct the drying process of the AAC construction. Therefore, the question about non-destructive detection of humidity distribution throughout the cross section of the material arises. Humidity distribution throughout the cross section of AAC masonry constructions has a significant impact on its heat resistivity properties. Application of electrical impedance spectrometry (EIS) method for determination of humidity distribution throughout the cross section of AAC constructions has been a subject of research recently. The EIS method is an easily applicable non-destructive testing method for detection of the humidity distribution throughout the cross section of a construction. Research on the impact of the external heat insulation layer on the speed of humidity distribution changes is described in this paper.

  13. Ergonomic evaluation of masons laying concrete masonry units and autoclaved aerated concrete.

    Science.gov (United States)

    Hess, Jennifer A; Kincl, Laurel; Amasay, Tal; Wolfe, Peter

    2010-05-01

    Masons working with concrete masonry unit block have high rates of work-related musculoskeletal disorders to the low back and shoulders associated with repetitively lifting and buttering heavy block. A new material, autoclaved aerated concrete, may reduce the risk of shoulder and back injury but, ergonomic evaluation is needed. This study evaluated shoulder exposure parameters, low back stress, and worker perceptions in two groups of journey level masons, one using CMU and the other using AAC block. Results indicate that for the left arm AAC masons spent significantly more time than CMU masons in static (38.2% versus 31.1%, respectively), and less time in slow motions (48.2% versus 52.2%, respectively) and faster motions (13.6% versus 16.7%, respectively) (p<0.05). CMU masons had significantly greater shoulder and low back pain (p=0.009) and they held block significantly longer than AAC masons (p<0.001). Low back compressive forces were high for both materials. Masons handling AAC demonstrated less left upper extremity stress but both materials were estimated to be hazardous to the low back. PMID:19926073

  14. [Model of regularity of ammonia transformation along marine biological aerated filter].

    Science.gov (United States)

    Luo, Rong-Qiang; Hou, Sha-Sha; Shen, Jia-Zheng; Chen, Zhu; Liu, Ying

    2012-09-01

    This study investigates the biological aerated filter (BAF) of a marine recirculating aquaculture system, which is important to remove harmful ammonia and organics. A model, characterizing the ammonia transformation along the BAF, was established on the basis of the principle of adsorption and the first order reaction bio-film. Experiments were performed and verified the effectiveness of the proposed model. The target BAF was packed with bamboo ring for 70 cm high. Study under the conditions [pH 7.1-7.6, DO 5-7 mg x L(-1), gas water ratio about 20 : 1, organic load about 4 g x (m3 x h)(-1)] shows that ammonia is removed significantly under the 10 cm height of medium, while less ammonia is removed between 10-70 cm. Experimental results confirm that the model predicts the ammonia concentration along the BAF accurately with a low influent ammonia concentration, but the predicted value is slightly lower than the true value with a high influent ammonia concentration. Study on ammonia concentration along the BAF reveals that the effluent ammonia concentration increases along with either the increment of the influent ammonia concentration or the reduction of the hydraulic retention time. PMID:23243879

  15. Nonlinear Modeling of Autoclaved Aerated Concrete Masonry Wall Strengthened using Ferrocement Sandwich Structure

    KAUST Repository

    M., Abdel-Mooty

    2011-01-01

    Autoclaved Aerated Concrete (AAC) block are used mainly as non-load-bearing walls that provide heat insulation. This results in considerable saving in cooling energy particularly in hot desert environment with large variation of daily and seasonal temperatures. However, due to the relatively low strength there use load bearing walls is limited to single storey and low-rise construction. A system to enhance the strength of the AAC masonry wall in resisting both inplane vertical and combined vertical and lateral loads using ferrocement technology is proposed in this research. The proposed system significantly enhances the load carrying capacity and stiffness of the AAC wall without affecting its insulation characteristics. Ferrocement is made of cement mortar reinforced with closely spaced wire mesh. Full scale wall specimens with height of 2100mm and width of 1820mm were tested with different configuration of ferrocement. A finite elementmodel is developed and verified against the experimentalwork. The results of the finite element model correlates well with the experimental results.

  16. DETERMINATION METHODOLOGY OF BIOMASS AND PAC AT AERATION UNIT IN PACT PROCESS

    Directory of Open Access Journals (Sweden)

    N.Jaffarzadeh

    2000-12-01

    Full Text Available In this research using two pilot scale systems of activated sludge (AS and powdered activated carbon technology (PACT, the soluble organic load removal efficiency was evaluated, for a synthetic wastewater with mono-ethylene glycol as carbon source. Also, the variations of biomass and PAC in each reactor were studied and the relative accuracy of differential ignition method for determining the amount of biomass and powdered activated carbon (combined in aeration unit of the PACT pilot was investigated. Results showed that the method might be used for the determination of PAC and biomass volatility at 400°C and 50°C, respectively, with acceptable accuracy. Comparison the results of this study and some other recent studies, show that there are no significant differences between them at 95% confidence. Furthermore, the results of this study indicated that there was little difference in carbon to biomass ratio which supports the concept that solid residence time (SRT and the amount of wastage sludge can be determined with total suspended solids analysis and there is no necessity for biomass determination

  17. Strain rate sensitivity of autoclaved aerated concrete from quasi-static regime to shock loading

    Directory of Open Access Journals (Sweden)

    Mespoulet Jérôme

    2015-01-01

    Full Text Available The quasi-static mechanical behavior of autoclaved aerated concrete is well-known and can be expressed as a function of its density. There are however not much studies dealing with its dynamic behavior and its damping ability when subjected to a mechanical shock or a blast. This study presents experimental results obtained at the Shock Physics Laboratory of THIOT INGENIERIE company. The test specimens are made of YTONG(TM cellular concrete with porosity in the range of 75 to 80%. Experimental tests cover a large strain rate amplitude (higher than 104 s−1 for specimens up to 250 mm. They were carried out with a small compression press and with two facilities dedicated to dynamic material characterization: JUPITER dynamic large press (2 MN, 3 ms rising time and TITAN multi-caliber single-stage gas gun. Results in un-confined conditions show an increase of the compressive strength when strain rate increases (45% increase at 5.102 s−1 but dynamic tests induce damage early in the experiment. This competition between dynamic strength raise and specimen fracture makes the complete compaction curve determination not to be done in unconfined dynamic condition. A 25% increase of the compressive strength has been observed between unconfined and confined condition in Q.S. regime.

  18. Combined effects of agitation and aeration on the chitinolytic enzymes production by the Antarctic fungus Lecanicillium muscarium CCFEE 5003

    Directory of Open Access Journals (Sweden)

    Fenice Massimiliano

    2012-01-01

    Full Text Available Abstract Background The Antarctic fungus Lecanicillium muscarium CCFEE 5003 is one of the most powerful chitinolytic organisms. It can produce high level of chitinolytic enzymes in a wide range of temperatures (5-30°C. Chitinolytic enzymes have lot of applications but their industrial production is still rather limited and no cold-active enzymes are produced. In view of massive production of L. muscarium chitinolytic enzymes, its cultivation in bioreactors is mandatory. Microbial cultivation and/or their metabolite production in bioreactors are sometime not possible and must be verified and optimized for possible exploitation. Agitation and aeration are the most important parameters in order to allow process up-scaling to the industrial level. Results In this study, submerged cultures of L. muscarium CCFEE 5003 were carried out in a 2-L bench-top CSTR bioreactor in order to optimise the production of chitinolytic enzymes. The effect of stirrer speed (range 200-500 rpm and aeration rate (range 0.5-1.5 vvm combination was studied, by Response Surface Methodology (RSM, in a medium containing 1.0% yeast nitrogen base and 1% colloidal chitin. Optimization was carried out, within a "quadratic D-optimal" model, using quantitative and quantitative-multilevel factors for aeration and agitation, respectively. The model showed very good correlation parameters (R2, 0.931; Q2, 0.869 and the maximum of activity (373.0 U/L was predicted at ca. 327 rpm and 1.1 vvm. However, the experimental data showed that highest activity (383.7 ± 7.8 U/L was recorded at 1 vvm and 300 rpm. Evident shear effect caused by stirrer speed and, partially, by high aeration rates were observed. Under optimized conditions in bioreactor the fungus was able to produce a higher number of chitinolytic enzymes than those released in shaken flasks. In addition, production was 23% higher. Conclusions This work demonstrated the attitude of L. muscarium CCFEE 5003 to grow in bench

  19. PENGGUNAAN MEMBRAN SERAT BERONGGA SEBAGAI AERATOR DALAM SISTEM KULTIVASI UNTUK MENINGKATKAN PRODUKSI BIOMASSA DAN BIOFIKSASI CO2 DARI Chlorella vulgaris

    Directory of Open Access Journals (Sweden)

    D Dianursanti

    2015-06-01

    Full Text Available Pemanasan global yang memicu terjadinya perubahan iklim, sebagian besar disebabkan karena merebaknya gas CO2.  Pemanfaatan mikroalga Chlorella sp. untuk mereduksi gas CO2 menjadi potensi yang menjanjikan. Hal ini mengingat, bahwa Chlorella dapat dengan efisien mereduksi CO2 karena mereka dapat tumbuh dengan cepat dan mudah diadaptasikan ke dalam rekayasa sistem fotobioreaktor. Dalam penelitian ini akan diupayakan pengaturan sistem aerasi berfilter untuk kultivasi Chlorella vulgaris dalam reaktor agar proses transfer massa gas CO2 dalam kultur mikroalga menjadi lebih baik. Dengan demikian nilai KLa (CO2 menjadi salah satu parameter penentu dalam peningkatan produksi biomassa Chlorella. Nilai KLa yang tinggi menunjukkan proses transfer massa CO2 yang lebih baik dalam kultur mikroalga. Namun nilai KLa (CO2 yang terlalu besar sangat mungkin menyebabkan terjadinya shear stress pada alga.Dengan menggunakan membran serat berongga sebagai aerator, permasalahan shear stress pada alga dapat dihindari. Dengan diameter pori yang sangat kecil, membran ini dapat memberikan laju alir dan transfer massa CO2 dalam kultur yang optimal, tanpa menimbulkan efek shear strees. Dengan demikian penggunaan membran ini dapat menghasilkan produktivitas Chlorella yang lebih baik serta dapat meningkatkan kemampuan biofiksasi CO2 selama proses kultivasinya. Penggunaan membran serat berongga sebagai aerator telah terbukti mampu meningkatkan produksi biomassa C. vulgaris  sebesar 27,2 %. Abstract Global warming triggering climate change is largely due to the presence of CO2. Utilization of microalgae Chlorella vulgaris to reduce CO2 gas is potential as it efficiently reduces CO2while growing quickly and adapting to the photobioreactor systems engineering. This study explored filter aeration system settings for cultivating C. vulgaris in the reactor thus mass transfer of CO2 in microalgae cultures becomes more efficient. Value of KLa (CO2 is one of the parameters in

  20. Measuring aeration system oxygen transfer in field conditions using the offgas method; Medida de la transferencia de oxigeno de sistemas de aireacion en condiciones de campo usando el metodo offgas

    Energy Technology Data Exchange (ETDEWEB)

    Trillo Fox, I.

    1998-10-01

    The high energy consumption of aeration systems has made optimisation of both design and operation of such systems an issue of major concern. This paper describes the techniques available for the measurement of oxygen transfer efficiency of aeration systems in process conditions, key information to achieve optimisation, and includes detailed discussion on the use of Off-Gas techniques to overcome the uncertainties encountered in efficient operation and design of aeration systems. (Author) 7 refs.

  1. Dipping of Eggs, Use of Low Temperature and Aeration to Improve Fruit Fly Bactrocera Carambolae (Drew and Hancock) Mass Rearing in Sterile Insect Technique Programme

    International Nuclear Information System (INIS)

    In the Sterile Insect Technique (SIT) programme a large number of homogenous age of pupae should be produced to be sterilized and released into the field. A methodology to preserve eggs which at the same time delay the egg hatch is needed in the production of a large number of pupae with homogenous age. The study on method of preserving fruit fly eggs the effect of dipping, low temperature, on the viability of eggs, the quality of larvae hatched from the eggs, and the quality of pupae produced were observed. Viability of eggs were observed as percent of egg hatch, quality of larvae as number of pupae produced from 0.5 ml of eggs when reared on artificial diet, and quality of pupae as percent of the flies number emerged and flew from the pupae. In room temperature (26 oC) dipping did not preserve fruit fly eggs and aeration did not improve the preservation. Although after one day dipping the viability of eggs only decreased from 90 % (control) to 80.5 %, (without aeration) and 81.5 % (with aeration) it decreased the number of pupae been produced from 1447 pupae (control) to 382 pupae (without aeration) and 616 pupae (with aeration). Low temperature successfully preserved the egg up to 24 hours. After 24 hour dipping in low temperature (16 oC) the viability of eggs were decreased up to 84.75 % (without aeration) and able to produce 1104 pupae. Aeration during dipping in low temperature did not improve the preservation. (author)

  2. Feasibility of In-Situ Aeration of Old Dumping Ground for Land Reclamation

    Directory of Open Access Journals (Sweden)

    Huan-Huan Tong

    2013-12-01

    Full Text Available Dumping grounds are characterized by the absence of engineering controls such as base liners and cover layer. Consequently, these dumping grounds present risks for surrounding resources such as soil, groundwater and air. The concern for groundwater contamination by leachate from tropical dumping grounds is heightened due to the greater amounts of rainfall and subsequent infiltration and percolation through the waste mass. The emergent demand for old dumping grounds reclamation drives the need to employ remediation technologies. Generally, in-situ aeration is a remediation method that promotes aerobic conditions in the later stage of dumping ground. It accelerates carbon transfer, reduces remaining organic load, and generally shortens the post closure period. However, high rainfall in tropical areas straitens this technique. For example, pollutants could be easily flushed out and more energy should be required to overcome hydrostatic pressure. Although heavy rainfall could supply sufficient water to the substrate and accelerate degradation of organic matter, it may inhibit aerobic activities due to limited air transfer. The waste characterization from Lorong Halus Dumping Ground (closed dumping ground in Singapore showed that the waste materials were stabilized after 22 years closure. According to the Waste Acceptance Criteria set by European Communities Council, the waste materials could be classified as inert wastes. One interesting finding was that leachate layer detected was about of 5 - 8 meter depth, which entirely soaked the waste materials. Hence, the reclamation design and operation should be carefully adjusted according to these characters. Lorong Halus Dumping Ground case study can provide a guideline for other tropical closed landfills or dumping grounds.

  3. Intermittent feeding of wastewater in combination with alternating aeration for complete denitrification and control of filaments.

    Science.gov (United States)

    Kantartzi, Styliani; Melidis, Paraschos; Aivasidis, Alexander

    2010-01-01

    In the present study, a laboratory scale system, consisting of a primary settling tank, a continuous stirred tank reactor and a clarifier were constructed and operated, using wastewater from the municipal wastewater treatment plant in Xanthi, Greece. The system operated under intermittent aeration in aerobic/anoxic conditions and feeding of the wastewater once in every cycle. The unit was inoculated with sludge, which originated from the recirculation stream of the local wastewater treatment plant. The wastewater was processed with hydraulic retention time (HRT) of 12 h, in which various experimental states were studied regarding the combination of aerobic and anoxic intervals. The wastewater was fed in limited time once in every cycle of aerobic/anoxic conditions at the beginning of the anoxic period. The two states that exhibited highest performance in nitrification and total nitrogen removal were, then, repeated with HRT of 10 h. The results show that, regarding the nitrification stage and the organic load removal, the intermittent system achieved optimum efficiency, with an overall removal of biological oxygen demand (BOD(5)) and ammonium nitrogen in the range of 93-96% and 91-95% respectively. As far as the total nitrogen removal is concerned, and if the stage of the denitrification is taken into account, the performance of the intermittent system surpassed other methods, as it is shown by the total Kjeldahl nitrogen (TKN) removal efficiency of 85-87%. These operating conditions suppressed the growth of filamentous organisms, a fact reflected at the SVI values, which were lower than 150 ml/g. PMID:20418622

  4. Analysis of Process Gases and Trace Contaminants in Membrane-Aerated Gaseous Effluent Streams.

    Science.gov (United States)

    Coutts, Janelle L.; Lunn, Griffin Michael; Meyer, Caitlin E.

    2015-01-01

    In membrane-aerated biofilm reactors (MABRs), hollow fibers are used to supply oxygen to the biofilms and bulk fluid. A pressure and concentration gradient between the inner volume of the fibers and the reactor reservoir drives oxygen mass transport across the fibers toward the bulk solution, providing the fiber-adhered biofilm with oxygen. Conversely, bacterial metabolic gases from the bulk liquid, as well as from the biofilm, move opposite to the flow of oxygen, entering the hollow fiber and out of the reactor. Metabolic gases are excellent indicators of biofilm vitality, and can aid in microbial identification. Certain gases can be indicative of system perturbations and control anomalies, or potentially unwanted biological processes occurring within the reactor. In confined environments, such as those found during spaceflight, it is important to understand what compounds are being stripped from the reactor and potentially released into the crew cabin to determine the appropriateness or the requirement for additional mitigation factors. Reactor effluent gas analysis focused on samples provided from Kennedy Space Center's sub-scale MABRs, as well as Johnson Space Center's full-scale MABRs, using infrared spectroscopy and gas chromatography techniques. Process gases, such as carbon dioxide, oxygen, nitrogen, nitrogen dioxide, and nitrous oxide, were quantified to monitor reactor operations. Solid Phase Microextraction (SPME) GC-MS analysis was used to identify trace volatile compounds. Compounds of interest were subsequently quantified. Reactor supply air was examined to establish target compound baseline concentrations. Concentration levels were compared to average ISS concentration values and/or Spacecraft Maximum Allowable Concentration (SMAC) levels where appropriate. Based on a review of to-date results, current trace contaminant control systems (TCCS) currently on board the ISS should be able to handle the added load from bioreactor systems without the need

  5. Electroflotation clarifier to enhance nitrogen removal in a two-stage alternating aeration bioreactor.

    Science.gov (United States)

    Cho, Kangwoo; Chung, Chong Min; Kim, Yun Jung; Hoffmann, Michael R; Chung, Tai Hak

    2013-01-01

    Stringent water treatment criteria and rapidly growing pollutant loads provoke the demand for retrofitting wastewater treatment plants towards a higher capacity. In this study, we assess a two stage alternating aeration (AA) bioreactor equipped with electroflotation (EF) clarifier, for nitrogen removal within a short hydraulic retention time (HRT). The EF under steady solids loading required a minimum unit height and gas: solids ratio of 0.006 for efficient clarification. The separated sludge blanket was further thickened with retaining stability when the cyclic solids loading was smaller than 1.0 kg m(-2). In the continuous operation of the bioreactor, the returned activated sludge concentration increased to more than 18,000 mg L(-1), while the effluent suspended solids concentration was lowered below 5 mg L(-1). Under influent chemical oxygen demand (COD)/total inorganic nitrogen (TIN) concentration of 300/30 mg L(-1), the TIN removal efficiency was near 70% with cycle time ratios of 0.17 and 0.27. Under higher influent COD concentration of 500mg L(-1), TIN removal efficiency was found to be 73.4% at a carbon:nitrogen (C:N) ratio of 10 and even higher (80.4%) at a C:N ratio of 16.6. The increased mixed liquor suspended solids concentrations (> 6000 mg L(-1)) under the high COD loading were efficiently maintained by using the EF clarifier. The results of this study demonstrate that an EF clarifier with a HRT of less than 1 h can support reliable nitrogen removal in the AA process that has a HRT of 6 h, even under increasing influent loadings. PMID:24527640

  6. Comparison of Aeration Strategies for Optimization of Nitrogen Removal in an Adsorption/Bio-oxidation (A/B) Process with an Emphasis on Ammonia vs. NOx (AvN) control

    OpenAIRE

    Sadowski, Michael Stuart

    2015-01-01

    Research was performed at a pilot-scale wastewater treatment plant operating an adsorption/bio-oxidation (A/B) process at 20C. The study compared B-Stage performance under DO Control, Ammonia Based Aeration Control (ABAC), and Ammonia vs. NOx (AvN) control. AvN in 1) fully-intermittent and 2) intermittently-aerated MLE configurations was compared to DO Control and ABAC, each with continuous aeration, in an MLE configuration. The study also examined operation of each aeration strategy with two...

  7. Thermal balance of aerated lagoons and waste stabilization ponds in temperate climate

    International Nuclear Information System (INIS)

    Very few studies have ever focused on the thermal balance of a wastewater treatment process, despite its major impact on various aspects of sanitary engineering, such as biological growth, oxygen transfer and, most importantly, purification kinetics. This lack of knowledge is particularly worrying for the design of aerated lagoons and waste stabilization ponds, since these two extensive treatment technologies are extremely dependent on climatic conditions and subject to high thermal variations. In temperate regions, a pond annual temperature range can even exceed 20 °C, while a 10 °C variation will induce a more than 60% drop or increase in its removal yield. Our paper intends to present a comprehensive temperature prediction model which accounts for the main heat loss and gain terms exchanged through the pond surface and walls. Our approach includes six different energy inputs and outputs, namely: solar radiation, air-water surface convection, atmospheric radiation, back surface radiation, evaporation and ground-water-walls convection. Each of these components was described extensively by means of a literature review of all previous efforts made to predict equilibrium temperature in lakes, rivers, salt-gradient solar ponds, cooling tanks, even outdoor pools. The best aspects of each prediction model were then incorporated into a new computer model developed as two different but complementary variants: one for steady-state conditions and the other for continuous and therefore also transient simulations. The main difference between these two approaches is that the first one neglects enthalpy variation while the second one takes the form of a differential equation, with basin temperatures being estimated by an iterative calculation procedure and a numerical integration method, respectively. Two hypotheses were necessary to develop this model. The first one posits that pond hydrodynamics correspond to completely mixed conditions. Such hydraulic behavior is extremely

  8. 几种机械增氧方式在池塘养殖中的增氧性能比较%Performance comparison for different mechanical aeration methods in pond

    Institute of Scientific and Technical Information of China (English)

    谷坚; 顾海涛; 门涛; 刘兴国; 曹建军

    2011-01-01

    为评价池塘养殖中主要机械增氧方式的性能优劣,该文通过增氧清水试验和水产养殖池塘中实地试验,研究了几种机械增氧方式在清水试验中的增氧能力,动力效率和实际池塘中的溶解氧变化.结果表明,在清水中,叶轮增氧机增氧能力分别高出水车和螺旋桨增氧机4%和264%,动力效率分别高出12.7%和259%;在池塘中,叶轮增氧机对池塘水层的混合均匀时间要比水车和螺旋桨增氧机快40%,对溶解氧的增加值分别高115%和293%.叶轮增氧机综合增氧性能要高于水车和螺旋桨增氧机,螺旋桨增氧机综合增氧性能最差.该研究为在池塘养殖中合理运用机械增氧方式提供了有益的借鉴.%In order to compare the performance indexes of the main mechanical aeration methods in pond culture, the aeration capacity in clean water test, the changes of dissolved oxygen in actual pond and the power efficiency for some kinds of mechanical aeration methods were studied through historical and current data of clean water oxygenation test and field experiments in ponds. The results indicated that the aeration capacity of impeller aerator was 4% and 264%higher than those of paddlewheel aerator and propeller aerator respectively; the power efficiency of impeller aerator was 12.7% and 259% higher than those of paddlewheel aerator and propeller aerator respectively in clean water; the time to achieve the water layer mixing uniformity for impeller aerator was 40% less than those for paddlewheel aerator and propeller aerator, and the increasing values of dissolved oxygen for impeller aerator was 115% and 293% higher than those for paddlewheel aerator and propeller aerator respectively in pond. The comprehensive aeration performance of impeller aerator is higher than that of paddlewheel aerator and propeller aerator, and the propeller aerator has the worst comprehensive aeration performance. The study can provide useful references for

  9. Comparison between lab- and full-scale applications of in situ aeration of an old landfill and assessment of long-term emission development after completion.

    Science.gov (United States)

    Hrad, Marlies; Gamperling, Oliver; Huber-Humer, Marion

    2013-10-01

    Sustainable landfilling has become a fundamental objective in many modern waste management concepts. In this context, the in situ aeration of landfills has been recognised for its potential to convert conventional anaerobic landfills into biological stabilised state, whereby both current and potential (long-term) emissions of the landfilled waste are mitigated. In recent years, different in situ aeration concepts have been successfully applied in Europe, North America and Asia, all pursuing different objectives and strategies. In Austria, the first full-scale application of in situ landfill aeration by means of low pressure air injection and simultaneous off-gas collection and treatment was implemented on an old, small municipal solid waste (MSW) landfill (2.6ha) in autumn 2007. Complementary laboratory investigations were conducted with waste samples taken from the landfill site in order to provide more information on the transferability of the results from lab- to full-scale aeration measures. In addition, long-term emission development of the stabilised waste after aeration completion was assessed in an ongoing laboratory experiment. Although the initial waste material was described as mostly stable in terms of the biological parameters gas generation potential over 21days (GP21) and respiration activity over 4days (RA4), the lab-scale experiments indicated that aeration, which led to a significant improvement of leachate quality, was accompanied by further measurable changes in the solid waste material under optimised conditions. Even 75weeks after aeration completion the leachate, as well as gaseous emissions from the stabilised waste material, remained low and stayed below the authorised Austrian discharge limits. However, the application of in situ aeration at the investigated landfill is a factor 10 behind the lab-based predictions after 3years of operation, mainly due to technical limitations in the full-scale operation (e.g. high air flow resistivity due

  10. 我国池塘增氧技术现状与发展趋势%The development status, issues and trends of pond aeration technology in China

    Institute of Scientific and Technical Information of China (English)

    顾海涛; 王逸清

    2014-01-01

    The technology of pond aeration have developed in China for over 40 years since the emergence of first impeller aerator in 1972, which is one of the main driving factors that the total aquaculture output of China ranked first in the world for 24 consecutive years. This article analyzed the current status of the pond aeration technology in China, classified and elaborated impeller aerator, wave aerator and aerator with solar technology as mature technology, innovative technology and budding technology respectively. Simultaneously, the issues such as lack of evaluation method for the innovative technology, weak research and development capabilities and small efforts for new technology extension were put forward, which are all the bottleneck for the further development of pond aeration technology. Finally, the development trends of pond aeration technology were discussed based on new changes and features of aquaculture industry, such as the low energy consumption, recirculating aquaculture system, and the application of digital and intelligent technology in pond aeration.%以1972年第一台叶轮式增氧机的诞生为标志,池塘增氧技术在我国发展了40多年,它是我国养殖总产量连续24年位居世界第一的主要因素之一。通过对目前国内池塘增氧技术的现状进行分析,将叶轮式增氧机、涌浪式增氧机和太阳能技术在池塘增氧中的应用分别划分为成熟技术、创新技术和萌芽技术,并进行了阐述;指出目前存在的缺乏对创新技术的评价方法、研发能力不足、缺少对新技术的推广力度等问题是制约池塘增氧技术进一步发展的瓶颈,同时结合水产养殖发展的新变化、新特点,对池塘增氧技术发展的趋势进行了探讨。

  11. 池塘微孔曝气和叶轮式增氧机的增氧性能比较%Comparison of oxygen-enriched performances of micropore and impeller aerators in pond

    Institute of Scientific and Technical Information of China (English)

    谷坚; 徐皓; 丁建乐; 车轩; 顾兆俊

    2013-01-01

    In high stocking density closed pond aquaculture, the farmed fish will suffer death from suffocation if no additional oxygen is supplied. Currently, there are various kinds of aeration methods in China, mainly including the types of impeller, water wheel, jet, propeller, and micropore aerator. The micropore aeration as the main form of bottom aeration method has been becoming one of the main aeration methods applied and expanded in China pond aquaculture in recent years. This study aimed at a systematic comparative analysis on the aeration effect and practical usage between a micropore aerator and an impeller aerator that has the best comprehensive performance and currently holds the dominant position in mechanical aeration in China, through a clean water test and a fishpond experiment. In order to study the oxygen-enriched performance of a micropore aerator and an impeller aerator in pond fish culture, we conducted the clean water oxygen-enriched performance test with the same power (2.2 kW) micropore aerator and an impeller aerator in the standard tank with a diameter of 10 meters according to the requirements described in the fisheries industry standard-“SC/T 6009-1999, the test method of oxygen-enriched capacity for aerator.”According to the experiment requirements, the tap water which was kept for a period was deoxidized using sodium sulfite (Na2SO3), and then was aerated again, while the time-variable data of dissolved oxygen (DO) concentration were measured and recorded. The oxygen-enriched capacity (Qs) and power efficiency (Es) were calculated for the impeller aerator and the micropore aerator with the obtained experiment data. The comparative experiments of actual oxygen-enriched performance and pond dissolved oxygen values variation for both aerators were conducted in a fishpond. One micropore aerator (combined with a 2.2 kW blower, 8 35-metre-long pipes were arranged in parallel with 10-meter intervals at the bottom of fish pond, the total pipe

  12. 涌浪机标准参数研究%Research on the standard parameters of wave aerator

    Institute of Scientific and Technical Information of China (English)

    王玮; 韩梦遐

    2014-01-01

    由于养殖池塘水体受温度、气压、光合作用、盐度、养殖鱼类等多种因素影响而不断发生变化,使涌浪机的质量较难定量分析。为了制定切实可行的涌浪机行业标准,开展了涌浪机标准参数的研究。试验参考了SC/T 6009《增氧机增氧能力试验方法》的标准检测程序,利用实验室直径8.0 m的标准水池作为试验平台,试验水温20℃,气压101.325 kPa,初始溶氧浓度为0 mg/L,试验用水为自来水,对3种涌浪机进行对比试验研究。结果表明:净浮力、绝缘电阻等基本参数用增氧机标准评判仍然可行;空载噪声、增氧能力、动力效率等参数变化较大;宜增加提水能力和造浪强度参数,以适应对涌浪机的评判。%It is difficult to quantitatively analyze the performance of wave aerator, due to the fact that the water in culture pond constantly changes with various factors such as temperature, air pressure, photosynthesis, salinity and farmed species, etc. we carried out the research on the standard parameters of wave aerator in order to develop its practical and feasible industry standard. Using the eight-meter diameter laboratory standard tank as a testing platform, the experiment was conducted at 20 ℃ water temperature, 101. 325 kPa air pressure, and 0 mg/L initial concentration of dissolved oxygen, by reference to the standard testing procedure described in the "SC/T 6009-1999 Test methods of oxygen-enriched capacity for aerator". The comparative experiment was done for three types of wave aerators in clean water. The experiment results showed that it was still feasible to judge the basic parameters such as net buoyancy rate and insulation resistivity by using the criteria of aerator; and the other parameters such as no-load noise, oxygen transfer capacity and power efficiency changed greatly;the parameter values of water-lifting capacity and wave-generating intensity should be increased to

  13. Mathematical model analysis on the enhancement of aeration efficiency using ladder-type flat membrane module forms in the Submerged Membrane Bio-reactor(SMBR)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules,improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held,and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased.This can improve scouring action of membrane surface on aeration and reduce energy consumption of strong aeration in SMBR.By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries,the relatively suitable incline angle θ under certain aeration place and in certain size rang of bubble can be obtained with the computer iterative calculation technology.Finally,for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR,some sugges-tions are offered:the interval distance of membrane modules is 8―15 mm,and aeration should be op-erated at 5―7 mm among membrane modules,and the optimal design angle of trapeziform membrane is 1.7°―2.5°.

  14. The lfy ash aerated concrete pouring stability is discussed%粉煤灰加气混凝土浇注稳定性探讨

    Institute of Scientific and Technical Information of China (English)

    苏琳

    2014-01-01

    加气混凝土浇注稳定性是加气混凝土生产至关重要的一环,浇筑稳定性的优劣直接影响加气混凝土制品的质量、产量。它在加气混凝土生产中起着决定性的作用,对制品的性能、生产效率都有着重大影响,保证浇筑稳定性是提高加气混凝土质量的重要技术关键。%the stability of the aerated concrete pouring is aerated concrete production is important one annulus,the stability of the casting quality directly affect the quality of aerated concrete products, production.It in aerated concrete production plays a decisive role,the performance of the products,has a major impact on production efficiency,ensure casting stability is an important key technology to improve the quality of aerated concrete.

  15. Mathematical model analysis on the enhancement of aeration efficiency using ladder-type flat membrane module forms in the Submerged Membrane Bio-reactor (SMBR)

    Institute of Scientific and Technical Information of China (English)

    LI Bo; YE MaoSheng; YANG FengLin; MA Hui

    2009-01-01

    The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor (SMBR) Is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules, improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held, and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased. This can improve scouring action ofmembrane surface on aeration and reduce energy consumption of strong aeration in SMBR. By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries, the relatively suitable Incline angle θ under certain aeration place and in certain size rang ofbubble can be obtained with the computer iterative calculation technology. Finally, for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR, some sugges-tions are offered: the interval distance of membrane modules is 8--15 mm, and aeration should be op-erated at 5--7 mm among membrane modules, and the optimal design angle of trapeziform membrane is 1.7°--2.5°.

  16. Carbon dioxide stimulates the production of amylovorin L by Lactobacillus amylovorus DCE 471, while enhanced aeration causes biphasic kinetics of growth and bacteriocin production.

    Science.gov (United States)

    Neysens, Patricia; De Vuyst, Luc

    2005-11-25

    The effects of both oxygen and carbon dioxide on growth of and product formation by Lactobacillus amylovorus DCE 471, a promising new sourdough starter culture, were assessed through controlled, in vitro fermentation experiments, using a temperature of 37 degrees C and a constant pH of 5.4. It was seen that aeration affected both cell growth and amylovorin L production. At aeration rates of 1 l min(-1) and more, the bacterial population was subjected to oxidative stress as reflected by biphasic growth patterns. During the first growth phase, the maximum specific growth rate increased with increasing aeration rates stabilizing at the highest oxygen concentrations. The maximum obtainable cell yields decreased. During the second growth phase, the amylovorin L production was stimulated at the highest aeration. However, amylovorin titers were never higher in the presence of oxygen compared with the anaerobic fermentations. Carbon dioxide did not influence cell growth of L. amylovorus DCE 471. The maximum specific growth rate and the biomass concentrations were merely affected. On the other hand, the maximum soluble bacteriocin titers coincided with the highest carbon dioxide flow rates. These results indicate that mild aeration of type II sourdoughs might enhance both cell yield and amylovorin L production by L. amylovorus DCE 471, thereby contributing to the competitiveness of the strain. Growth in an ecosystem together with yeasts producing carbon dioxide might exert a positive effect on the production of amylovorin L as well. PMID:16087265

  17. Research on the removal of radium from uranium effluent by air-aeration hydrated manganese hydroxide adsorption

    International Nuclear Information System (INIS)

    In the acidic leaching uranium process, pyrolusite or manganese oxide (MnO2) powder is often used as an oxidizer. In the processed effluent, manganese ion present as a contaminant in addition to U, Ra, Th, As, Zn, Cu, F, SO42-, etc. Manganese ion content is about 100∼200 mg/1 in effluent. In this case, a new process technique can be developed to treat the effluent using the Mn2+ present in the effluent. The approach is as follows: The effluent is neutralized by lime milk to pH about 11. As a result, most contaminants are precipitated to meet the uranium effluent discharge standards (U, Th, Mn, SO42- etc.), but radium is still present in the effluent. In this process, manganese ion forms manganese hydroxide Mn(OH)2. The manganese hydroxide is easily to oxide to form MnO(OH)2 by air aeration. This hydrated manganese hydroxide complex can then be used to adsorb radium in effluent. The experiments show: (1) Effluent pH, manganese concentration in effluent, and aeration strength and time etc. influence the radium removal efficiency. Under the test conditions, when manganese in effluent is between 100∼300 mg/l, and pH is over 10.5, radium can be reduced to lower 1.11 Bq/1 in the processed effluent. Higher contents of impurity elements such as aluminum, silicon and magnesium in the effluent affect the removal efficiency; (2) Under the experimental conditions, the lime precipitation air-aeration formed hydrated manganese hydroxide complex sludge is stable. There is no obvious release of radium from the adsorbed hydrated manganese hydroxide complex sludge; (3) The current experiments show that hydrated manganese hydroxide complex sludge has a very good re-adsorption ability for removal of radium from uranium effluent. Some experimental parameters have been measured. (author)

  18. Effect of C/N ratio, aeration rate and moisture content on ammonia and greenhouse gas emission during the composting

    Institute of Scientific and Technical Information of China (English)

    Tao Jiang; Frank Schuchardt; Guoxue Li; Rui Guo; Yuanqiu Zhao

    2011-01-01

    Gaseous emission (N2O,CH4 and NH3) from composting can be an important source of anthropogenic greenhouse gas and air pollution.A laboratory scale orthogonal experiment was conducted to estimate the effects of C/N ratio,aeration rate and initial moisture content on gaseous emission during the composting of pig faeces from Chinese Ganqinfen system.The resnits showed that about 23.9%to 45.6% of total organic carbon (TOC) was lost in the form of CO2 and 0.8% to 7.5% of TOC emitted as CH4.Most of the nitrogen was lost in the form of NH3,which account for 9.6% to 32.4% of initial nitrogen.N2O was also an important way of nitrogen losses and 1.5% to 7.3% of initial total nitrogen was lost as it.Statistic analysis showed that the aeration rate is the most important factor which could affect the NH3 (p =0.0189),CH4 (p =0.0113) and N2O (p =0.0493) emissions significantly.Higher aeration rates reduce the CH4 emission but increase the NH3 and N2O losses.C/N ratio could affect the NH3 (p =0.0442) and CH4 (p =0.0246) emissions significantly,but not the N2O.Lower C/N ratio caused higher NH3 and CH4 emissions.The initial moisture content can not influence the gaseous emission significantly.Most treatments were matured after 37 days,except a trial with high moisture content and a low C/N ratio.

  19. Combination process of limited filamentous bulking and nitrogen removal via nitrite for enhancing nitrogen removal and reducing aeration requirements.

    Science.gov (United States)

    Guo, Jianhua; Peng, Yongzhen; Yang, Xiong; Gao, Chundi; Wang, Shuying

    2013-03-01

    Limited filamentous bulking (LFB) activated sludge process was proposed by Guo et al. (2010) to increase the removal of tiny suspended particulates in the clarifier and reduce aeration energy consumption. However, when the use of LFB process, ammonium removal efficiency would be compromised due to low dissolved oxygen (DO). In this study, the combination process of nitrogen removal via nitrite and LFB was achieved to enhance nitrogen removal and reduce aeration energy consumption by controlling low DO levels (0.5-1.0 mg L(-1)) in a lab-scale anoxic-oxic reactor (V=66 L) treating real domestic wastewater at room temperature. Above 85% of nitrite accumulation ratio was steadily maintained during continuous operation period. The combined process improved the total nitrogen (TN) removal by about 20% in comparison to the traditional process via the nitrate pathway, and also reduced the specific aeration energy consumption by 35%. COD, ammonium and TN removal efficiencies were up to 86%, 94% and 75%, respectively. The process proved effective in achieving a steady LFB state, whereby sludge volume index between 150 and 250 mL g(-1) was sustained for long-term operation. The microbial community structure was analyzed by fluorescence in situ hybridization, which indicated ammonia-oxidizing bacteria out-competed nitrite-oxidizing bacteria. Moreover, the filaments Type 0041 and Microthrix parvicella proliferated with limited abundance. The results indicated the combination process of LFB and nitrogen removal via nitrite under low DO was a feasible solution for saving energy and enhancing nitrogen removal when treating domestic wastewater. PMID:23305749

  20. Characterization and modelling of the heat transfers in a pilot-scale reactor during composting under forced aeration

    International Nuclear Information System (INIS)

    The paper focused on the modelling of the heat transfers during composting in a pilot-scale reactor under forced aeration. The model took into account the heat production and the transfers by evaporation, convection between material and gas crossing the material, conduction and surface convection between gas and material in bottom and upper parts of the reactor. The model was adjusted thanks to the measurements practised during fifteen composting experiments in which five organic wastes were, each, composted under three constant aeration rates. Heat production was considered proportional to oxygen consumption rate and the enthalpy per mole oxygen consumed was assumed constant. The convective heat transfer coefficients were determined on basis of the continuous measurements of the temperatures of both the lid and the bottom part of the reactor. The model allowed a satisfying prediction of the temperature of the composting material. In most cases, the mean absolute discard between the experimental and the simulated temperatures was inferior to 2.5 °C and the peaks of temperature occurred with less than 8 h delay. For the half of the experiments the temperature discard between the simulated peak and the experimental one was inferior to 5 °C. On basis of the calculation of a stoichiometric production of water through oxidation of the biodegradable organic matter, the simulation of water going out from material as vapour also allowed a rather satisfying prediction of the mass of water in final mixture. The influence of the aeration rate on every type of heat loss was characterized. Finally, the model was used to evaluate the impacts on material temperature caused by the change of the insulation thickness, the ambient temperature, take the lid away, the increase or the decrease of the mass of waste to compost.

  1. Effects of aeration and natural zeolite on ammonium removal during the treatment of sewage by mesocosm-scale constructed wetlands.

    Science.gov (United States)

    Araya, F; Vera, I; Sáez, K; Vidal, G

    2016-07-01

    The objective was to evaluate the effects of intermittent artificial aeration cycles and natural zeolite as a support medium, in addition to the contribution of plants (Schoenoplectus californicus) on NH4(+)-N removal during sewage treatment by Constructed Wetlands (CW). Two lines of Mesocosm Constructed Wetland (MCW) were installed: (a) gravel line (i.e. G-Line) and (b) zeolite line (i.e. Z-Line). Aeration increased the NH4(+)-N removal efficiency by 20-45% in the G-Line. Natural zeolite increased the NH4(+)-N removal efficiency by up to 60% in the Z-Line. Plants contributed 15-30% of the NH4(+)-N removal efficiency and no difference between the G-Line and the Z-Line. Conversely, the NH4(+)-N removal rate was shown to only increase with the use of natural zeolite. However, the MCW with natural zeolite, the NH4(+)-N removal rate showed a direct relationship only with the NH4(+)-N influent concentration. Additionally, relationship between the oxygen, energy and area regarding the NH4(+)-N removal efficiency was established for 2.5-12.5 gO2/(kWh-m(2)) in the G-Line and 0.1-2.6 gO2/(kWh-m(2)) in the Z-Line. Finally, it was established that a combination of natural zeolite as a support medium and the aeration strategy in a single CW could regenerate the zeolite's adsorption sites and maintain a given NH4(+)-N removal efficiency over time. PMID:26848982

  2. Using a biological aerated filter to treat mixed water-borne volatile organic compounds and assessing its emissions

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen-Hsi

    2009-01-01

    A biological aerated filter (BAF) was evaluated as a fixed-biofilm processes to remove water-borne volatile organic compounds (VOCs) from a multiple layer ceramic capacitor (MLCC) manufacturing plant in southern Taiwan.The components of VOC were identified to be toluene,1,2,4-trimethylbenzene,1,3,5-trimethylbenzene,bromodichloromethane and isopropanol (IPA).The full-scale BAF was constructed of two separate reactors in series,respectively using 10-cm and 15-cm diameter polypropylene balls as the packing materials and a successful preliminary bench-scale experiment was performed to feasibility.Performance results show that the BAF removed over 90% chemical oxygen demand (COD) from the influent with (1188 ± 605) mg/L of COD.A total organic loading of 2.76 kg biochemical oxygen demand (BOD)/(m~3 packing·d) was determined for the packed bed,in which the flow pattern approached that of a mixed flow.A limited VOC concentration of (0.97 ± 0.29) ppmv (as methane) was emitted from the BAF system.Moreover,the emission rate of VOC was calculated using the proposed formula,based on an air-water mass equilibrium relationship,and compared to the simulated results obtained using the Water 9 model.Both estimation approaches of calculation and model simulation using Water 9 evaluating VOC emissions reveal that 0.1% IPA (0.0031-0.0037 kg/d) was aerated into a gaseous phase,and 30% to 40% (0.006-0.008 kg/d) of the toluene was aerated.

  3. DETERMINATION OF DESIGN CRITERIA OF AN H-IFAS REACTOR IN COMPARISON WITH AN EXTENDED AERATION ACTIVATED SLUDGE PROCESS

    Directory of Open Access Journals (Sweden)

    N. Mehrdadi , A. A. Azimi , G. R. Nabi Bidhendi, B. Hooshyari

    2006-01-01

    Full Text Available Advanced compact wastewater treatment processes are being looked for by cities all over the world as effluent standards are becoming more stringent and land available for treatment plants more scarce. In this investigation, a new biofilm process for this purpose was studied. The design and operational criteria of a full scale extended aeration activated sludge system was compared with an H-IFAS reactor which has been operated at a pilot scale. The objective was to define the feasibility of using the H-IFAS (Hybrid Integrated Fixed Film Activated Sludge reactor for upgrading the existing wastewater treatment plants with conventional processes. The results showed that besides the considerable difference between the organic loading of the two processes, H-IFAS reactor has a very good capability to reduce simultaneously the concentration of nitrogen and phosphorus. Organic degradation rate in extended aeration and H-IFAS systems were 0.3 and 6.22 kgCOD/m3.day at 23.48°C, respectively. Nitrification, denitrification and phosphorus removal rate for the H-IFAS reactor were 343.28 g N/m3.day, 338.17 gN/m3.day, and 204.78gPO4-P/m3.day, respectively. At the same conditions, these criteria for extended aeration activated sludge processes were obtained as 75gN/m3.day, 28.5 gN/m3.day and 7 gPO4-P/m3.day, respectively.

  4. Selection of Co-Substrate and Aeration Conditions for Vanillin Production by Escherichia coli JM109/pBB1

    OpenAIRE

    Torre, Paolo; De Faveri, Danilo; Perego, Patrizia; Converti, Attilio; Barghini, Paolo; Ruzzi, Maurizio; Faria, Fabrícia P.

    2004-01-01

    Yeast extract, Luria-Bertani medium and tryptone were tested as co-substrates for vanillin production from ferulic acid by resting cells of Escherichia coli JM109/pBB1. Yeast extract proved to be the best component for sustaining such a bioconversion, which is not self-sustained from the bioenergetic point of view. Tests were also performed under variable aeration conditions by simultaneously varying the ratio of medium to vessel volume and the agitation speed. The results of these tests sugg...

  5. The reactivity of the electron formed in the radiolysis of aerated alkaline aqueous solutions containing tetracycline hydrochloride, at 77 Ksup(+)

    International Nuclear Information System (INIS)

    The radiolysis of tetracycline hydrochloride dissolved in aerated alkaline aqueous solutions containing 0.1, 0.5 and 1M NaOH at 77 K, followed by ESR is reported. The rate constants for the reactions between the electron and physical or chemical traps which are present in these solutions are calculated. The reactivity of electrons that are formed in the radiolysis of water decreases in the following proportions: physical traps: chemical traps: molecules of water (4.8x10sup(14) : 6.5x10sup(8) : 1.0). The electrons react preferentially with the solute instead of the solvent. (author)

  6. 污水站曝气沉淀池改造%Renovation on sedimentation tank sewage aeration station

    Institute of Scientific and Technical Information of China (English)

    居鹏飞; 吴志峰

    2016-01-01

    对曝气沉淀池中心导流管进行改造,重新设计中心导流管长度,确定中心导流管喇叭口尺寸,加装底部反射板,使整个污水处理系统运行更加平稳高效。%The central draft tube sedimentation tanks aeration transform redesigned center draft tube length to determine the center of the draft tube flare size, the installation of the bottom of the reflector plate, the entire sewage treatment system run more smoothly and efficiently.

  7. The Value of Measuring Eustachian Tube Aeration on Temporal Bone CT in Patients with Chronic Otitis Media

    OpenAIRE

    Shim, Hyun Joon; Choi, A Young; Yoon, Sang Won; Kwon, Kee Hwan; Yeo, Seung Geun

    2010-01-01

    Objectives To evaluate that the cross-sectional area of the air space in the Eustachian tube (ET) on computed tomography (CT) images could be useful for predicting the postoperative aeration of the middle ear. Methods The patient group consisted of 80 patients (80 ears) with chronic otitis media and who underwent middle ear surgery from 2006-2007 and who were followed up for more than 1 yr. The control group consisted of 100 ears of 50 individuals with normal tympanic membranes and who underw...

  8. Cyber-physical system for a water reclamation plant: Balancing aeration, energy, and water quality to maintain process resilience

    Science.gov (United States)

    Zhu, Junjie

    Aeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at older WRPs can satisfy effluent permit requirements, they typically operate with excess aeration. More effective process controls at older WRPs can be challenging as operators work to balance higher energy costs and more stringent effluent limitations while managing fluctuating loads. Therefore, understandings of process resilience or ability to quickly return to original operation conditions at a WRP are important. A state-of-art WRP should maintain process resilience to deal with different kinds of perturbations even after optimization of energy demands. This work was to evaluate the applicability and feasibility of cyber-physical system (CPS) for improving operation at Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) Calumet WRP. In this work, a process model was developed and used to better understand the conditions of current Calumet WRP, with additional valuable information from two dissolved oxygen field measurements. Meanwhile, a classification system was developed to reveal the pattern of historical influent scenario based on cluster analysis and cross-tabulation analysis. Based on the results from the classification, typical process control options were investigated. To ensure the feasibility of information acquisition, the reliability and flexibility of soft sensors were assessed to typical influent conditions. Finally, the process resilience was investigated to better balance influent perturbations, energy demands, and effluent quality for long-term operations. These investigations and evaluations show that although the energy demands change as the influent conditions and process controls. In general, aeration savings could be up to 50% from the level of current consumption; with a more complex process controls, the saving could be up to 70% in relatively steady-state conditions and at least 40

  9. Experimental evaluation of the oxygen transfer in bubble aeration systems. Full scale experiences in lengthened activated sludge reactors

    International Nuclear Information System (INIS)

    The results of some full-scale oxygen transfer measurements conduced at the lengthened activate sludge tanks of two WWTPs of Trentino Region, are presented and discussed. As far at the tests in clean water are concerned, the non-liner regression method seems non accurate; important conclusion on the correlation between oxygen transfer process and typical parameters (i.e., fine-bubble diffusers, specific air flux) are derived. As far as the test in the wastewater is concerned, an increase of α-value from the inlet to the end of aeration tanks has been observed in the 'Andalo' WWTP

  10. Methane production and ebullition in a shallow, artificially aerated, eutrophic temperate lake (Lake Elsinore, CA)

    International Nuclear Information System (INIS)

    Methane is an important component of the gases released from lakes. Understanding the factors influencing the release is important for mitigating this greenhouse gas. The volume of methane (CH4) and other gases in sediments, and the rate of CH4 ebullition, were determined for an artificially aerated, shallow, eutrophic freshwater lake in Southern California. Gas volume was measured at 28 sites in July 2010, followed by monthly sampling at 7 sites through December 2011. Gas volumes measured in July 2010 at the 28 sites exhibited a complex dependence on sediment properties; the volume of CH4 and other gases was negligible in very coarse-textured sediment with low water and organic carbon contents. Gas volumes increased strongly with increased silt content, and were highest in sediments with intermediate water contents (60 to 70%), organic carbon contents (2 to 3%) and depths (approximately 4 m). Methane was the dominant gas collected from sediment (80 to 90%), while carbon dioxide comprised roughly 2 to 3% of sediment gas in the lake. Gas sampling during cool winter months revealed very low or undetectable volumes of gas present, while sediment gas volumes increased markedly during the spring and early summer months, and then declined in late summer and fall. The rate of CH4 ebullition, quantified with an echosounder, also varied markedly across the lake and seasonally. High rates of ebullition were measured at all 7 sites in July 2011 (up to 96 mmol CH4 m−2 d−1), while the rates were > 50% lower in September and negligible in December 2010. Ebullition rates were inversely correlated with depth and most other sediment properties, but strongly positively correlated with sand content. No simple relationship between ebullition rate and sediment gas volume across the set of sites was found, although ebullition rates at individual sites were strongly related to gas volume. - Highlights: • Volume of gas in sediments and rate of ebullition determined for a shallow

  11. Nitrogen removal by granular nitritation-anammox in an upflow membrane-aerated biofilm reactor.

    Science.gov (United States)

    Li, Xiaojin; Sun, Shan; Badgley, Brian D; Sung, Shihwu; Zhang, Husen; He, Zhen

    2016-05-01

    The nitritation-anammox process has been a promising nitrogen removal technology towards sustainable wastewater treatment, but its application in treating domestic wastewater with relatively low ammonium concentrations (mainstream) remains a great challenge. In this study, an innovative lab-scale upflow membrane-aerated biofilm reactor (UMABR) was employed to treat a synthetic wastewater containing 70 mg N L(-1) ammonium. With a DO level at 0.6 ± 0.1 mg O2 L(-1) and HRT of 32 h, the effluent ammonium concentration was 4.8 ± 2.0 mg N L(-1). Increasing the nitrogen loading rate from 52.4 to 104.8 g N m(-3) d(-1) with stepwise decreasing HRT from 32 to 16 h resulted in an average TN removal efficiency of 81% without nitrite accumulation. The average observed NO3(-)-N (residue)/NH4(+)-N (consumed) ratio of 8% was below the "theoretical ratio" of 13% and further reduction of nitrate residue needs to be addressed. Fluorescence in situ hybridization (FISH) and high-throughput sequencing analyses showed the coexistence of anammox bacteria and ammonium-oxidizing bacteria (AOB) in both biofilm and granular samples. Anammox bacteria accounted for up to 63.3% of the microbial community of the granules, with Candidatus Jettenia being the distinctly dominant anammox genus. In contrast, the biofilm contained abundant Nitrosomonadaceae (AOB, 33.1%). In addition, the brown-yellow granules exhibited a more balanced community structure with anammox bacteria and AOB accounting for 33.7% and 18.2%, respectively, which may contribute to the long-term operation of single-stage nitritation-anammox process. These results demonstrate that the nitritation-anammox UMABR could potentially be used for nitrogen removal from mainstream in some specific regions with relatively warm temperature. PMID:26921710

  12. Methane production and ebullition in a shallow, artificially aerated, eutrophic temperate lake (Lake Elsinore, CA)

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Denise; Anderson, Michael A., E-mail: michael.anderson@ucr.edu

    2013-06-01

    Methane is an important component of the gases released from lakes. Understanding the factors influencing the release is important for mitigating this greenhouse gas. The volume of methane (CH{sub 4}) and other gases in sediments, and the rate of CH{sub 4} ebullition, were determined for an artificially aerated, shallow, eutrophic freshwater lake in Southern California. Gas volume was measured at 28 sites in July 2010, followed by monthly sampling at 7 sites through December 2011. Gas volumes measured in July 2010 at the 28 sites exhibited a complex dependence on sediment properties; the volume of CH{sub 4} and other gases was negligible in very coarse-textured sediment with low water and organic carbon contents. Gas volumes increased strongly with increased silt content, and were highest in sediments with intermediate water contents (60 to 70%), organic carbon contents (2 to 3%) and depths (approximately 4 m). Methane was the dominant gas collected from sediment (80 to 90%), while carbon dioxide comprised roughly 2 to 3% of sediment gas in the lake. Gas sampling during cool winter months revealed very low or undetectable volumes of gas present, while sediment gas volumes increased markedly during the spring and early summer months, and then declined in late summer and fall. The rate of CH{sub 4} ebullition, quantified with an echosounder, also varied markedly across the lake and seasonally. High rates of ebullition were measured at all 7 sites in July 2011 (up to 96 mmol CH{sub 4} m{sup −2} d{sup −1}), while the rates were > 50% lower in September and negligible in December 2010. Ebullition rates were inversely correlated with depth and most other sediment properties, but strongly positively correlated with sand content. No simple relationship between ebullition rate and sediment gas volume across the set of sites was found, although ebullition rates at individual sites were strongly related to gas volume. - Highlights: • Volume of gas in sediments and rate

  13. Simple Analysis on Energy Efifciency Ratio of Aeration Equipment of Oxidation Channel%浅析氧化沟常用曝气设备的能效值

    Institute of Scientific and Technical Information of China (English)

    王月萍

    2014-01-01

    The paper presents the technical contrast and economic analysis of the several aeration equipment in the sewage treatment plant;explains the basic reasons of the energy efifciency ratio unbalance of the several aeration equipment;introduces one of the new type aeration equipment---its engineering construction accounting for a smal area, high efifciency and low consumption under the coequality technology condition.%对污水处理厂常用的几种曝气设备进行了技术对比和经济分析;简述了几种曝气设备能效比值不平衡的基本原因;介绍了一种在同等工艺条件下,工程构筑物占地面积小,高效、低耗的新型曝气设备。

  14. 改善气液传质的新型表面曝气装置%A Novel Surface Aeration Configuration for Improving Gas-Liquid Mass Transfer

    Institute of Scientific and Technical Information of China (English)

    禹耕之; 毛在砂; 王蓉

    2002-01-01

    A novel surface aeration configuration featured with a self-rotating and floating baffle (SRFB) and a Rnshton disk turbine (DT) with a perforated disk has been developed. The SRFB, consisted of 12 fan blades twisted by an angle of 30° to the horizontal plane, is incorporated onto the impeller shaft to improve gas entrainment, bubble breakup, mixing in a φ154 mm agitated vessel. This new configuration is compared to the conventional DT surface aeration experimentally. The results suggest that the critical impeller speed for onset of gas entrainment is lower for the new configuration and it demands greater power consumption. Moreover, the SRFB system produces 30%-68% higher volumetric mass transfer coefficient per unit power input than that obtained in the conventional DT surface aerator under the same operation conditions.

  15. 移动式太阳能增氧机的研制%Development and experiment of movable solar aerator

    Institute of Scientific and Technical Information of China (English)

    田昌凤; 刘兴国; 张拥军; 邹海生; 时旭; 车轩

    2015-01-01

    Dissolved oxygen (DO) is the most important factor in pond aquaculture. In order to reduce “oxygen debt” of water in the bottom and prevent fish from hypoxia in the next morning, aerators usually need to run which can stir the water in pond. However, this method consumes a lot of electrical energy and is of low efficiency. A movable solar aerator was designed by the software of Solidworks to solve these problems. It mainly consisted of solar power mechanism, water walking mechanism, aerator and working control system, which could move upon the water, generate waves and exchange amount of water from bottom to surface, etc. The solar power mechanism provided energy for the entire machine, while the water walking mechanism drives the whole machine to move on the water surface. The aerator orbits of the equipment could affect a large area of the pond. In order to verify the reliability of the system, the reliability of walking performance was tested under both idling and load situation by the experiment in which the walking test platform was separately proceeded on the ground and in the pond. First, to deploy the reliability test on the ground, the steel cable was fixed with the stainless steel stem with the diameter of 6 mm, and the locked position was located outside the stop block, so as to ensure there was sufficient gap between stainless steel stem and steel cable. Based on that, it would ensure the synchronous motion of steel cable and stainless steel stem while no interference issue between them. Additionally, to perform the reliability test in the pond, the 2 ends of the steel cable were fixed through the wooden stake. When the moving distance was separately set as 2, 3 and 4 m, after setting the parameters in the control system, the running time and the odometer of single track could be recorded separately. The test duration was 1 day, running 5 h per day with 3 replications, and the illumination intensity of movable solar aerator start-up was 1 7000 lx

  16. Abundance and potential metabolic activity of methanogens in well-aerated forest and grassland soils of an alpine region.

    Science.gov (United States)

    Hofmann, Katrin; Praeg, Nadine; Mutschlechner, Mira; Wagner, Andreas O; Illmer, Paul

    2016-02-01

    Although methanogens were recently discovered to occur in aerated soils, alpine regions have not been extensively studied for their presence so far. Here, the abundance of archaea and the methanogenic guilds Methanosarcinales, Methanococcales, Methanobacteriales, Methanomicrobiales and Methanocella spp. was studied at 16 coniferous forest and 14 grassland sites located at the montane and subalpine belts of the Northern Limestone Alps (calcareous) and the Austrian Central Alps (siliceous) using quantitative real-time PCR. Abundance of archaea, methanogens and the methanogenic potentials were significantly higher in grasslands than in forests. Furthermore, methanogenic potentials of calcareous soils were higher due to pH. Methanococcales, Methanomicrobiales and Methanocella spp. were detected in all collected samples, which indicates that they are autochthonous, while Methanobacteriales were absent from 4 out of 16 forest soils. Methanosarcinales were absent from 10 out of 16 forest soils and 2 out of 14 grassland soils. Nevertheless, together with Methanococcales they represented the majority of the 16S rRNA gene copies quantified from the grassland soils. Contrarily, forest soils were clearly dominated by Methanococcales. Our results indicate a higher diversity of methanogens in well-aerated soils than previously believed and that pH mainly influences their abundances and activities. PMID:26712349

  17. Influence of phenol on ammonia removal in an intermittent aeration bioreactor treating biologically pretreated coal gasification wastewater.

    Science.gov (United States)

    Xu, Chunyan; Han, Hongjun; Jia, Shengyong; Zhao, Qian

    2016-05-01

    A laboratory-scale intermittent aeration bioreactor was investigated to treat biologically pretreated coal gasification wastewater that was mainly composed of NH3-N and phenol. The results showed that increasing phenol loading had an adverse effect on NH3-N removal; the concentration in effluent at phenol loading of 40mgphenol/(L·day) was 7.3mg/L, 36.3% of that at 200mg phenol/(L·day). The enzyme ammonia monooxygenase showed more sensitivity than hydroxylamine oxidoreductase to the inhibitory effect of phenol, with 32.2% and 10.5% activity inhibition, respectively at 200mg phenol/(L·day). Owing to intermittent aeration conditions, nitritation-type nitrification and simultaneous nitrification and denitrification (SND) were observed, giving a maximum SND efficiency of 30.5%. Additionally, ammonia oxidizing bacteria (AOB) and denitrifying bacteria were the main group identified by fluorescent in situ hybridization. However, their relative abundance represented opposite variations as phenol loading increased, ranging from 30.1% to 17.5% and 7.6% to 18.2% for AOB and denitrifying bacteria, respectively. PMID:27155414

  18. Alkalinity and pH effects on nitrification in a membrane aerated bioreactor: an experimental and model analysis.

    Science.gov (United States)

    Shanahan, John W; Semmens, Michael J

    2015-05-01

    A nitrifying biofilm was grown in a laboratory-scale membrane aerated bioreactor (MABR) to calibrate and test a one-dimensional biofilm model incorporating chemical equilibria to calculate local pH values. A previously developed model (Shanahan and Semmens, 2004) based upon AQUASIM was modified to incorporate the impact of local pH changes within the biofilm on the kinetics of nitrification. Shielded microelectrodes were used to measure the concentration profiles of dissolved oxygen, ammonium, nitrate, and pH within the biofilm and the overlying boundary layer under actual operating conditions. Operating conditions were varied to assess the impact of bicarbonate loading (alkalinity), ammonium loading, and intra-membrane oxygen partial pressure on biofilm performance. Nitrification performance improved with increased ammonium and bicarbonate loadings over the range of operating conditions tested, but declined when the intra-membrane oxygen partial pressure was increased. Minor discrepancies between the measured and predicted concentration profiles within the biofilm were attributed to changes in biofilm density and vertical heterogeneities in biofilm structure not accounted for by the model. Nevertheless, predicted concentration profiles within the biofilm agreed well with experimental results over the range of conditions studied and highlight the fact that pH changes in the biofilm are significant especially in low alkalinity waters. The influent pH and buffer capacity of a wastewater may therefore have a significant impact on the performance of a membrane-aerated bioreactor with respect to nitrification, and nitrogen removal. PMID:25703659

  19. Determining the optimal transmembrane gas pressure for nitrification in membrane-aerated biofilm reactors based on oxygen profile analysis.

    Science.gov (United States)

    Wang, Rongchang; Xiao, Fan; Wang, Yanan; Lewandowski, Zbigniew

    2016-09-01

    The goal of this study was to investigate the effect of transmembrane gas pressure (P g) on the specific ammonium removal rate in a membrane-aerated biofilm reactor (MABR). Our experimental results show that the specific ammonium removal rate increased from 4.98 to 9.26 gN m(-2) day(-1) when P g increased from 2 to 20 kPa in an MABR with a biofilm thickness of approximately 600 μm. However, this improvement was not linear; there was a threshold of P g separating the stronger and weaker effects of P g. The ammonium removal rate was improved less significantly when P g was over the threshold, indicating that there is an optimal threshold of P g for maximizing ammonium removal in an MABR. The change in oxygen penetration depth (d p) is less sensitive to P g in the ammonia-oxidizing active layer than in the inactive layer in membrane-aerated biofilm. The location of the P g threshold is at the same point as the thickness of the active layer on the curve of d p versus P g; thus, the active layer thickness and the optimal P g can be determined on the basis of the changes in the slope of d p to P g. PMID:27170321

  20. Enhancement of Bacillus subtilis Lipopeptide Biosurfactants Production through Optimization of Medium Composition and Adequate Control of Aeration

    Directory of Open Access Journals (Sweden)

    Dhouha Ghribi

    2011-01-01

    Full Text Available Interest in biosurfactants has increased considerably in recent years, as they are potentially used in many commercial applications in petroleum, pharmaceuticals, biomedical, and food processing industries. Since improvement of their production was of great importance to reduce the final coast, cultural conditions were analyzed to optimize biosurfactants production from Bacillus subtilis SPB1 strain. A high yield of biosurfactants was obtained from a culture of B. subtilis using carbohydrate substrate as a carbon source; among carbohydrates, glucose enhanced the best surfactin production. The optimum glucose concentration was 40 g/L. Higher amount of biosurfactants was obtained using 5 g/L of urea as organic nitrogen source and applying C/N ratio of 7 with ammonium chloride as inorganic nitrogen source. The highest amount of biosurfactants was recorded with the addition of 2% kerosene. Moreover, it was shown, using an automated full-controlled 2.6 L fermenter, that aeration of the medium, which affected strongly the growth regulated biosurfactants synthesis by the producing cell. So that, low or high aerations lead to a decrease of biosurfactants synthesis yields. It was found that when using dissolved oxygen saturation of the medium at 30%, biosurfactants production reached 4.92 g/L.

  1. Effects of superoxide dismutase, dithiothreitol and formate ion on the inactivation of papain by hydroxyl and superoxide radicals in aerated solutions

    International Nuclear Information System (INIS)

    Losses in enzyme activity and sulphydryl content have been studied in aerated papain solutions containing formate, superoxide dismutase and dithiothreitol. Both formate and dithiothreitol converted .OH to .02-, whereas superoxide dismutase completely suppressed the inactivation by .02-. Using results from all systems, the fraction of .02- reactions with papain that caused inactivation of the enzyme was 0.33+-0.07. The results also showed that the fraction of .OH reactions, which cause inactivation of papain, is significantly higher in aerated than in oxygen-free solutions. (author)

  2. Investigation of the performance of aerated sand traps at the sewage treatment plant; Untersuchungen zur Leistungsfaehigkeit von beluefteten Sandfaengen auf Klaeranlagen

    Energy Technology Data Exchange (ETDEWEB)

    Hirschbeck, Christina

    2010-07-01

    Aerated sand traps have the task to separate mineral particles with a grain diameter largely more or equal to a defined separation size to a percentage, while smaller particles and organic materials are passed on the following stages. So far, there is no standardised measurement method for the degree of separation of sand in sand trap plants. This complicates the proof whether the demanded degree of separation is kept. Under this aspect, the author of the contribution under consideration examines the efficiency of aerated sand traps on purification plants. Additionally, proposals to the testing method of sand traps and to conclusions and calculation references are derived.

  3. Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

    OpenAIRE

    Naulchan Khongsay; Lakkana Laopaiboon; Prasit Jaisil; Pattana Laopaiboon

    2012-01-01

    Optimization of three parameters: agitation rate (A; 100, 200 and 300 rpm), aeration rate (B; 0.5, 1.5 and 2.5 vvm) and aeration timing (C; 2, 4 and 6 h), for ethanol production from sweet sorghum juice under very high gravity (VHG, 290 g L−1 of total sugar) conditions by Saccharomyces cerevisiae NP 01 was attempted using an L9 (34) orthogonal array design. The fermentation was carried out at 30 °C in a 2-L bioreactor and the initial yeast cell concentration was approximately 2 × 107 cells mL...

  4. Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

    OpenAIRE

    Naulchan Khongsay; Lakkana Laopaiboon; Prasit Jaisil; Pattana Laopaiboon

    2012-01-01

    Optimization of three parameters: agitation rate (A; 100, 200 and 300 rpm), aeration rate (B; 0.5, 1.5 and 2.5 vvm) and aeration timing (C; 2, 4 and 6 h), for ethanol production from sweet sorghum juice under very high gravity (VHG, 290 g L −1 of total sugar) conditions by Saccharomyces cerevisiae NP 01 was attempted using an L 9 (3 4 ) orthogonal array design. The fermentation was carried out at 30 °C in a 2-L bioreactor and the initial yeast cell concentration was approximately 2 × 10 7 ...

  5. The extent of the influence and flux estimation of volatile mercury from the aeration pool in a typical coal-fired power plant equipped with a seawater flue gas desulfurization system

    International Nuclear Information System (INIS)

    Before being discharged, the waste seawater from the flue gas desulfurization system of coal-fired power plants contains a large amount of mercury, and is treated in aeration pools. During this aeration process, part of the mercury enters the atmosphere, but only very limited impact studies concerning this have been carried out. Taking a typical Xiamen power plant as an example, the present study targeted the elemental mercury emitted from the aeration pool. Concentrations of dissolved gaseous mercury as high as 1.14 ± 0.17 ng·L−1 were observed in the surface waste seawater in the aeration pool, and gaseous elemental mercury (GEM) as high as 10.94 ± 1.89 ng·m−3 was found in the air above the pool. To investigate the area affected by this GEM through air transfer, the total mercury in the dust and topsoil samples around the aeration pool were analyzed. Much higher values were found compared to those at a reference site. Environmental factors other than solar radiation had limited influence on the concentrations of the mercury species in the pool. A simulation device was built in our laboratory to study the flux of mercury from the aeration pool into the air. The results showed that more than 0.59 kg of mercury was released from the aeration pool every year, occupying 0.3% of the total mercury in the waste seawater. The transfer of mercury from water to air during the aeration pool and its environmental influence should not be ignored. - Highlights: ► High concentration of volatile mercury was observed in the aeration pool. ► More than 0.3% of total discharged Hg emitted from the pool into the air. ► Higher aeration rate resulted in more mercury emitted into the air. ► The dust and topsoil around the pool were polluted with the mercury

  6. Study on the oxygenation effect of wave aerator on Erythroculter ilishaeformis culture%涌浪机对翘嘴红鲌精养塘溶氧调控效果研究

    Institute of Scientific and Technical Information of China (English)

    吴明林; 李海洋; 侯冠军; 程云生; 蒋阳阳

    2012-01-01

    为探究涌浪机增氧效果,进行了不同天气下(晴天、夜间、阴雨天)涌浪机(0.75 kW)与叶轮式增氧机(3.0 kW)对精养塘溶氧与水质调控对比试验.测试显示:晴天,相对于起始时溶氧,涌浪机塘上下水层最大升幅分别为6.4 mg/L、7.1 mg/L,较叶轮式增氧机塘(5.9 mg/L、6.5 mg/L)和对照塘(5.3 mg/L、4.0 mg/L)高,涌浪机增氧能力较佳;夜间,涌浪机塘上下层溶氧在3.0 mg/L、1.6 mg/L左右,低于叶轮式增氧机(3.8 mg/L、2.6 mg/L),增氧效果欠佳;阴雨天,3个塘口上层溶氧最大升幅分别为:涌浪机1.7 mg/L,叶轮式增氧机2.6 mg/L,对照塘1.0 mg/L,涌浪机增氧次于叶轮式增氧机.pH值分析表明,长期使用涌浪机,pH值更接近于鱼类最适范围(7.0 ~8.5),可改善水质.因此,涌浪机应与其他增氧机械配合使用,将会取得更好的增氧效果.%In order to find a more efficient aeration way for guiding the production practice, the effects of different aeration methods using one 0. 75 kW wave aerator and one 3. 0 kW impeller aerator under different weather conditions were compared ( fine weather、night、rainy days). The results showed that under fine weather conditions, relative to the starting dissolved oxygen concentration at 8:30am, the upper and lower water layers increased 6. 4 mg/L and 7. 1 mg/L which were higher than the control pond (5.3 mg/L and 4.0 mg/L) and impeller aerator pond(5.9 mg/L, 6.5 mg/L). This showed that the aeration effect of the wave aerator was better than the impeller aerator. However, at night, the wave aerator maintained the concentration at 3. 0 mg/L and 1. 6 mg/L which were below the impeller aerator pond (3.8 mg/L, 2. 6 mg/ L). The result suggested that the aeration effect in the wave aerator pond was bad. In the rainy days, the dissolved oxygen concentration increased in three ponds. The largest increase of the upper dissolved oxygen concentrations respectively were; the wave aerator 1. 7mg/L, the impeller

  7. Minimization of nitrous oxide emission from CASS process treating low carbon source domestic wastewater: Effect of feeding strategy and aeration rate.

    Science.gov (United States)

    Liang, Weihao; Yu, Chao; Ren, Hongqiang; Geng, Jinju; Ding, Lili; Xu, Ke

    2015-12-01

    Nitrous oxide (N2O) emission during wastewater treatment can be mitigated by improving operational conditions, e.g., organic carbon supply and dissolved oxygen. To evaluate the control parameters for N2O emission in the low carbon source domestic wastewater treatment process, N2O emissions from Cyclic Activated Sludge System (CASS) under different feeding strategies and aeration rates were investigated. Results showed that continuous feeding enhanced nitrogen removal and reduced N2O emission compared to batch feeding, while a higher aeration rate led to less N2O emission. N2O was mainly produced during non-aeration phases in batch feeding CASS and the amount of N2O generated from denitrification decreased under continuous feeding, indicating that carbon source in the continuous influent relieved the electron competition between denitrification reductases during non-aeration phase. Moreover, taxonomic analysis based on high-throughput 16S rRNA gene sequencing revealed higher abundance of denitrifying bacteria, especially N2O-reducing bacteria in continuous feeding CASS. PMID:26386420

  8. Spatial patterns of radial oxygen loss and nitrate net flux along adventitious roots of rice raised in aerated or stagnant solution

    NARCIS (Netherlands)

    Rubinigg, M; Stulen, G; Elzenga, JTM; Colmer, TD

    2002-01-01

    Roots of rice (Oryza sativa L.) grown in stagnant de-oxygenated solution contain a 'tight' barrier to radial oxygen loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. It is generally accepted that the barrier to ROL involves anatomical modifications in the apoplast

  9. Comparison of compostable bags and aerated bins with conventional storage systems to collect the organic fraction of municipal solid waste from homes. a Catalonia case study.

    Science.gov (United States)

    Puyuelo, Belén; Colón, Joan; Martín, Patrícia; Sánchez, Antoni

    2013-06-01

    The separation of biowaste at home is key to improving, facilitating and reducing the operational costs of the treatment of organic municipal waste. The conventional method of collecting such waste and separating it at home is usually done by using a sealed bin with a plastic bag. The use of modern compostable bags is starting to be implemented in some European countries. These compostable bags are made of biodegradable polymers, often from renewable sources. In addition to compostable bags, a new model of bin is also promoted that has a perforated surface that, together with the compostable bag, makes the so-called "aerated system". In this study, different combinations of home collection systems have been systematically studied in the laboratory and at home. The results obtained quantitatively demonstrate that the aerated bin and compostable bag system combination is effective at improving the collection of biowaste without significant gaseous emissions and preparing the organic waste for further composting as concluded from the respiration indices. In terms of weight loss, temperature, gas emissions, respiration index and organic matter reduction, the best results were achieved with the aerated system. At the same time, a qualitative study of bin and bag combinations was carried in 100 homes in which more than 80% of the families participating preferred the aerated system. PMID:23490360

  10. A Guide for Developing Standard Operating Job Procedures for the Activated Sludge - Aeration & Sedimentation Process Wastewater Treatment Facility. SOJP No. 5.

    Science.gov (United States)

    Mason, George J.

    This guide for developing standard operating job procedures for wastewater treatment facilities is devoted to the activated sludge aeration and sedimentation process. This process is for conversion of nonsettleable and nonfloatable materials in wastewater to settleable, floculated biological groups and separation of the settleable solids from the…

  11. Model-based evaluation of the role of Anammox on nitric oxide and nitrous oxide productions in membrane aerated biofilm reactor

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Smets, Barth F.; Yuan, Zhiguo;

    2013-01-01

    A multispecies one-dimensional biofilm model considering nitric oxide (NO) and nitrous oxide (N2O) productions for membrane aerated biofilm reactor (MABR) that remove nitrogen autotrophically through aerobic ammonia oxidation followed by Anammox is used to study the role of Anammox activity on th...

  12. Sidewall-box airlift pump provides large flows for aeration, CO2 stripping, and water rotation in large dual-drain circular tanks

    Science.gov (United States)

    Conventional gas transfer technologies for aquaculture systems occupy a large amount of space, require a considerable capital investment, and can contribute to high electricity demand. In addition, diffused aeration in a circular culture tank can interfere with the hydrodynamics of water rotation a...

  13. Surviving floods: leaf gas films improve O2 and CO2 exchange, root aeration, and growth of completely submerged rice

    DEFF Research Database (Denmark)

    Pedersen, Ole; Rich, Sarah Meghan; Colmer, Timothy David

    2009-01-01

    artificially, underwater net photosynthesis declined to only 20% of the rate with gas films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in...

  14. Aeration control by monitoring the microbiological activity using fuzzy logic diagnosis and control. Application to a complete autotrophic nitrogen removal reactor

    DEFF Research Database (Denmark)

    Boiocchi, Riccardo; Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine;

    2015-01-01

    microbial groups on the other hand, the diagnosis provides information on: nitritation, nitratation, anaerobic ammonium oxidation and overall autotrophic nitrogen removal. These four results give insight into the state of the process and are used as inputs for the controller that manipulates the aeration to...

  15. 间歇曝气和连续曝气对生物脱氮除磷效果的比较%Biological Nitrogen and Phosphorus Removal Efficiency by Intermittent Aeration and Continues Aeration Compared

    Institute of Scientific and Technical Information of China (English)

    潘敏; 黄晓鸣

    2015-01-01

    采用序批式生物反应器SBR系统,考察反应阶段的间歇曝气和连续曝气对模拟生活废水中氮和磷的去除效果。研究表明: IASBR和SBR对NH4+-N的去除率分别为99�30%和98�73%;对PO3-4-P的去除率分别为97�02%和67�47%。间歇曝气SBR对氨氮和磷酸根的去除率比连续曝气SBR高,有利于实现强化生物脱磷过程。间歇曝气SBR出水中氮、磷和COD浓度均达到了我国城镇污水处理厂污染物排放标准(GB 18918—2002)一级标准。%Biological nitrogen and phosphorus removal was investigated by an intermittently aerated sequencing batch reactor IASBR and a sequencing batch reactor SBR . The removal efficiencies of ammonium⁃nitrogen NH4+⁃N were 99�30% and 98�73% respectively in IASBR and SBR in steady operation while phosphorus PO3-4 ⁃P removal efficiencies were 97�02% and 67�47% in IASBR and SBR respectively. The intermittent aeration pattern has better effect for biological phosphorus removal. Effluent NH4+⁃N PO3-4 ⁃P and COD concentrations in the IASBR meets ChinaⅠEmission Standards.

  16. 间歇曝气和连续曝气对生物脱氮除磷效果的比较%Biological Nitrogen and Phosphorus Removal Efficiency by Intermittent Aeration and Continues Aeration Compared

    Institute of Scientific and Technical Information of China (English)

    潘敏; 黄晓鸣

    2015-01-01

    Biological nitrogen and phosphorus removal was investigated by an intermittently aerated sequencing batch reactor IASBR and a sequencing batch reactor SBR . The removal efficiencies of ammonium⁃nitrogen NH4+⁃N were 99�30% and 98�73% respectively in IASBR and SBR in steady operation while phosphorus PO3-4 ⁃P removal efficiencies were 97�02% and 67�47% in IASBR and SBR respectively. The intermittent aeration pattern has better effect for biological phosphorus removal. Effluent NH4+⁃N PO3-4 ⁃P and COD concentrations in the IASBR meets ChinaⅠEmission Standards.%采用序批式生物反应器SBR系统,考察反应阶段的间歇曝气和连续曝气对模拟生活废水中氮和磷的去除效果。研究表明: IASBR和SBR对NH4+-N的去除率分别为99�30%和98�73%;对PO3-4-P的去除率分别为97�02%和67�47%。间歇曝气SBR对氨氮和磷酸根的去除率比连续曝气SBR高,有利于实现强化生物脱磷过程。间歇曝气SBR出水中氮、磷和COD浓度均达到了我国城镇污水处理厂污染物排放标准(GB 18918—2002)一级标准。

  17. Phospholipid fatty acids in mitochondria and microsomes of wheat and rice seedling roots during aeration and anaerobiosis

    International Nuclear Information System (INIS)

    Mitochondrial and microsomal fractions were isolated from the roots after residence of wheat and rice seedlings under conditions of aeration or anaerobiosis and used to determine the percentage ratio of phospholipid fatty acids (PFA), their content, and the rate of incorporation of [2-14C]-acetate into them. In rice mitochondria under anaerobic influence, the ratio of unsaturated to saturated PFA was higher than the level that occurred in the control plants and PFA content remained close to the control level throughout the entire course of exposure. On the other hand, these indices declined in wheat mitochondria and microsomes of both plants. Anoxia also powerfully inhibited incorporation of labelled acetate into PFA of both membrane fractions in wheat and rice seedlings alike. Probably indicating adaptive reorganizations in composition of the main groups of PFA and inhibition of their decomposition in rice mitochondria, the obtained data are discussed in relation to greater resistance to temporary anaerobiosis in rice as compared with wheat

  18. Multi-stage diffused bubble aeration system for the removal of volatile organics and radon--A case history

    International Nuclear Information System (INIS)

    Community acceptance of a water treatment plant project in the 1990's is just as important as the technical performance of the equipment. The low profile of the multi-stage diffused bubble aeration system, as well as the technical performance of this equipment, provides the perfect solution for water treatment facilities that are constructed in residential areas. This case history involves the installation of a multi-stage diffused bubble system in a residential neighborhood in New Jersey without compromising any of the aesthetic qualities. As a result of a routine monitoring program, low levels of trichloroethylene were detected in the outcrop area. At the same time, routine analysis for radon in the source of supplies indicated that the wells located in the outcrop area showed levels of radon between 800 and 1,150 picoCuries per liter

  19. Rapid Start-up and Loading of an Attached Growth, Simultaneous Nitrification/Denitrification Membrane Aerated Bioreactor

    Science.gov (United States)

    Meyer, Caitlin E.; Pensinger, Stuart; Pickering, Karen D.; Barta, Daniel; Shull, Sarah A.; Vega, Letticia M.; Christenson, Dylan; Jackson, W. Andrew

    2015-01-01

    Membrane aerated bioreactors (MABR) are attached-growth biological systems used for simultaneous nitrification and denitrification to reclaim water from waste. This design is an innovative approach to common terrestrial wastewater treatments for nitrogen and carbon removal and implementing a biologically-based water treatment system for long-duration human exploration is an attractive, low energy alternative to physiochemical processes. Two obstacles to implementing such a system are (1) the "start-up" duration from inoculation to steady-state operations and (2) the amount of surface area needed for the biological activity to occur. The Advanced Water Recovery Systems (AWRS) team at JSC explored these two issues through two tests; a rapid inoculation study and a wastewater loading study. Results from these tests demonstrate that the duration from inoculation to steady state can be reduced to under two weeks, and that despite low ammonium removal rates, the MABRs are oversized.

  20. Thermophysical characteristics of low density autoclaved aerated concrete and their influence on durability of exterior walls of buildings

    Directory of Open Access Journals (Sweden)

    A.B. Krutilin

    2015-03-01

    Full Text Available The paper presents the results of experimental studies of thermophysical characteristics of autoclaved aerated concrete with density of 400 and 500 kg/m3. The dependence of thermal conductivity on temperature and humidity was determined. The boundary humidities were set for which ice is either not formed or its amount is negligible in the pores of the materials at the temperature below zero. The new method of non-isothermal liquid transport coefficient determination was suggested. It was found that one of the basic mechanisms of moving water for cellular concrete samples with a moisture content over 30 % by weight is non-isothermal liquid transport. The effect of humidity on durability of exterior walls is estimated according to cellular concrete frost-resistance tests.