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Sample records for biological nitrification inhibition

  1. Evidence for biological nitrification inhibition in Brachiaria pastures

    OpenAIRE

    Subbarao, G. V.; Nakahara, K.; Hurtado, M. P.; Ono, H.; Moreta, D. E.; Salcedo, A. F.; Yoshihashi, A. T.; T. Ishikawa; Ishitani, M.; Ohnishi-Kameyama, M.; Yoshida, M.; M Rondon; Rao, I. M.; Lascano, C. E.; Berry, W. L.

    2009-01-01

    Nitrification, a key process in the global nitrogen cycle that generates nitrate through microbial activity, may enhance losses of fertilizer nitrogen by leaching and denitrification. Certain plants can suppress soil-nitrification by releasing inhibitors from roots, a phenomenon termed biological nitrification inhibition (BNI). Here, we report the discovery of an effective nitrification inhibitor in the root-exudates of the tropical forage grass Brachiaria humidicola (Rendle) Schweick. Named ...

  2. BIOLOGICAL NITRIFICATION OF WASTE WATER

    Directory of Open Access Journals (Sweden)

    P. B. N. Lakshmi Devi

    2014-11-01

    Full Text Available Nitrification has been studied extensively as a result of its significance within the biological process and at intervals the necessity for treatment of waste water. In the last decade, the treatment of high ammonical concentration effluents has become a matter of nice interest. Many effluents will contain some hundred milligrams of nitrogen per liter (supernatants from anaerobic digestion, lechates from municipal water, etc. may have specific treatment before utilization them to the plant recycling process. Sometimes this reaction is applied by maintaining robust ammonical concentrations which have the role of inhibiting the nitrite – oxidizing population responsible for the reaction of nitrites into nitrates (final stage of nitrification. However the nitrification methods served as a very important basis for the development of today understands and mathematical models for several waste treatment processes (activated sludge process using biofilm reactors and self – purification in rivers. Often nitrogen removal from sea wastewater is problematic due to the low rate of bacteria concerned. Immobilization is an economical technique to retain slow growing organisms in continuous flow reactors. Immobilized cells can be classified into “naturally” attached cells (biofilms and “artificially” immobilized cells. The simultaneous nitrification and denitrification within the step feeding biological nitrogen removal method were investigated below different inflowing substrate and aeration flow rates. The experimental results showed that there was additionally linear relationship between simultaneous nitrification and denitrification and DO concentration below the conditions of low and high aeration rate.

  3. A DO- and pH-based early warning system of nitrification inhibition for biological nitrogen removal processes.

    Science.gov (United States)

    Hong, Seil; Choi, Il; Lim, Byung Jin; Kim, Hyunook

    2012-01-01

    In Korea, more than 80% of municipal wastewater treatment plants (WWTPs) with capacities of 500 m3·d-1 or more are capable of removing nitrogen from wastewater through biological nitrification and denitrification processes. Normally, these biological processes show excellent performance, but if a toxic chemical is present in the influent to a WWTP, the biological processes (especially, the nitrification process) may be affected and fail to function normally; nitrifying bacteria are known very vulnerable to toxic substances. Then, the toxic compound as well as the nitrogen in wastewater may be discharged into a receiving water body without any proper treatment. Moreover, it may take significant time for the process to return back its normal state. In this study, a DO- and pH-based strategy to identify potential nitrification inhibition was developed to detect early the inflow of toxic compounds to a biological nitrogen removal process. This strategy utilizes significant changes observed in the oxygen uptake rate and the pH profiles of the mixed liquor when the activity of nitrifying bacteria is inhibited. Using the strategy, the toxicity from test wastewater with 2.5 mg·L-1 Hg2+, 0.5 mg·L-1 allythiourea, or 0.25 mg·L-1 chloroform could be successfully detected. PMID:23443381

  4. Inhibition of nitrification in soil by metal diethyldithiocarbamates

    Institute of Scientific and Technical Information of China (English)

    A. Arora; Bijay Singh; Dhiraj Sud; T.Srivastava; C. L. Arora

    2003-01-01

    Nitrification acts as a key process in determining fertilizer use efficiency by crops as well as nitrogen losses from soils. Metal dithiocarbamates in addition to their pesticidal properties can also inhibit biological oxidation of ammonium(nitrification) in soil. Metal [M=V(III), Cr(III), Mn(II), Fe(III), Ni(II), Cu(II), Zn(II) and Pt(IV)] diethyldithiocarbamates (DEDTC) were synthesized by the reaction of sodium diethyldithiocarbamate with metal chloride in dichloromethane/water mixture. These metal diethyldithiocarbamates were screened for their ability to inhibit nitrification at different concentrations(10 μg/g soil, 50 μg/g soil and 100 μg/g soil). With increasing concentration of the complex, capacity to retard nitrification increased but the extent of increase varied for different metals. At 100 μg/g soil, different complexes showed nitrification inhibition from 22.36% to 46.45%. Among the diethyldithiocarbamates tested, Zn(DEDTC)2 proved to be the most effective nitrification inhibitor at 100 μg/g soil. Manganese, iron and chromium diethyldithiocarbamates also proved to be effective nitrification inhibitors than the others at 100 μg/g soil. The order of percent nitrification inhibition in soil by metal diethyldithiocarbamates was: Zn(II) > Mn(II) > Fe(III) > Cr(III) >V(III) > Co(II) > Ni(II) > Cu(II).

  5. Examination of nitrification inhibition by sorghum (Sorghum bicolor) in soil around its roots

    OpenAIRE

    Adel Ghoneim; Abdulla Al-Modaihsh; Saied Naeem, et al.

    2014-01-01

    Biological nitrification inhibition refers to release some chemical substances from plant root that suppresses/slowdown soil nitrification. This study was conducted to clarify whether sorghum (Sorghum bicolor) inhibit nitrification in soil around the root. Sorghum cultivated in pots filled with a brown lowland soil and examined nitrification rate in the soil around its root comparing with bare soil. Two experiments were conducted. In the first experiment, sorghum was cultivated in a growth ch...

  6. Bioassays for the determination of nitrification inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Grunditz, Camilla

    1999-07-01

    Requirements for nitrogen reduction in wastewater treatment plants were introduced in Sweden in the early 1990's. This was a governmental move to reduce the nitrogen discharges to the Baltic and Kattegat in order to prevent eutrophication. The nitrification process in wastewater treatment plants is performed by nitrifying bacteria. These are susceptible to inhibition and it is of great importance that the influent water does not contain toxic compounds. Therefore, there is a need for assays for the determination of nitrification inhibition. This thesis describes the development and applications of such bioassays. Pure cultures of Nitrosomonas sp. and Nitrobacter sp. were isolated from activated sludge of a wastewater treatment plant. These cultures were used as test organisms in the development of bioassays for nitrification inhibition measurements. The assays are based on two different principles; cell suspensions of the bacteria, performed in test tubes, and mediated amperometric biosensors with the bacteria immobilised. Ammonia oxidation and nitrite oxidation are studied separately without interference from other organisms, which makes it easier to interpret the results. The cell suspension assays were applied to samples of industrial and municipal wastewater. The Nitrosomonas and Nitrobacter assays showed to have different inhibition patterns. A large percentage of the Swedish municipal wastewater treatment plants were found to receive inhibitory influent water, but the inhibition level was generally low. Compared to an assay based on activated sludge, the screening method, the pure culture assays found more samples of influent water strongly inhibitory or stimulating. The highest correlation was found between the screening method and the Nitrosomonas assay. The Nitrobacter assay was found to be the most sensitive method. Assessment of toxicity of a number of chemical substances was studied using the biosensors, together with the cell suspension assays

  7. Inhibition of Nitrification by Creosote-Contaminated Water

    DEFF Research Database (Denmark)

    Dyreborg, Søren; Arvin, Erik

    1995-01-01

    A leaching experiment was carried out in a saturated sand column contaminated with creosote. The toxicity of the leachate was determined by the inhibition of nitrification. Good correlations between the toxicity and the concentrations of five selected creosote compounds (benzene, toluene, o...

  8. Cocurrent biological nitrification and denitrification in wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Spector, M.

    1998-11-01

    Repetitive conditioning of recycle activated sludge (RAS) under strict anaerobic conditions gradually changes the products of ammonia oxidation from nitrite and nitrate to nitrous oxide (N{sub 2}O) and nitrogen (N{sub 2}). Nitrite inhibits oxygen respiration of anaerobically conditioned sludge; biochemical oxygen demand (BOD) is then oxidized by nitrite, which is reduce to N{sub 2}O and N{sub 2}. When anaerobic RAS conditioning is initially imposed on a nitrifying system, Nitrobacter species continue to oxidize nitrite to nitrate and thus reduce the nitrite available to oxidize BOD. However, Nitrobacter in the mixed liquor gradually tend to wash out because the sole source of Nictrobacter energy, the oxidation of nitrite to nitrate, is diminished to the extent that nitrite is reduced. Incorporation of an RAS conditioning zone to the activate-sludge process results in evolution of a nonfilamentous biomass, which affects both cocurrent biological nitrification and denitrification (CBND) and biological phosphorus removal (BPR). The initial feed zone may be either aerobic or anaerobic. A final anoxic denitrification zone is desirable for removal of residual nitrite plus nitrate (NO{sub x}) from aeration effluent. Nitrous oxide, the main reaction product of CBND, promotes both global warming and destruction of the stratospheric ozone layer.

  9. Applying Molecular Tools for Monitoring Inhibition of Nitrification by Heavy Metals

    Science.gov (United States)

    The biological removal of ammonia in conventional wastewater treatment plants (WWTPs) is performed by promoting nitrification and denitrification as sequential steps. The first step in nitrification, the oxidation of ammonia to nitrite by ammonia oxidizing bacteria (AOB), is sens...

  10. Wastewater Treatment in a Hybrid Biological Reactor (HBR) :Nitrification Characteristics

    Institute of Scientific and Technical Information of China (English)

    JIAN-LONG WANG; LI-BO WU

    2004-01-01

    To investigate the nitrifying characteristics of both suspended- and attached- biomass in a hybrid bioreactor. Methods The hybrid biological reactor was developed by introducing porous ceramic particles into the reactor to provide the surface for biomass attachment. Microorganisms immobilized on the ceramics were observed using scanning electron microscopy (SEM). All chemical analyses were performed in accordance with standard methods. Results The suspended- and attached-biomass had approximately the same nitrification activity. The nitrifying kinetic was independent of the initial biomass concentration, and the attached-biomass had a stronger ability to resist the nitrification inhibitor. Conclusion The attached biomass is superior to suspended-biomass for nitrifying wastewater, especially that containing toxic organic compounds. The hybrid biological reactor consisting of suspended- and attached-biomass is advantageous in such cases.

  11. Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    Huiqiang Li; Hongjun Han; Maoan Du; Wei Wang

    2011-01-01

    Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater.Nitrification of the MBBR was inhibited almost completely during start-up period.Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition.Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little effect on nitrification recovery.Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days.Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water.The ratio of nitrification decreased to 25% when infiuent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70%for another 4 days.

  12. Modelisation of Nitrification under Inhibited Environment by Moving Bed Bio-Film Reactor Technique

    Directory of Open Access Journals (Sweden)

    Pham T.H. Duc

    2010-01-01

    Full Text Available Problem statement: Nitrification by Moving Bed Biofilm Reactor (MBBR involves physical, chemical and biological processes to remove toxic ammonia for aquaculture that are governed by a variety of parameters, like substrate and dissolved oxygen concentrations, organic matters, temperature, pH, alkalinity and turbulence level, which impact negatively or positively on nitrification kinetics. Approach: The situation becomes more serious as the reaction rate is inhibited by low ammonium concentration and high salinity. That problems usually occur in treatment systems of aquatic breeding hatcheries. Results: In this study, experiments have been conducted to evaluate the impact of salinity on nitrification rate through kinetic constant (k and reaction order (n based on general equation v = kCn. Moving bed biofilm reactor was operated continuously at same initial amounts of nitrogen and Phosphorus very low (oligotrophic conditions. Firstly, over view the impact of salinity on kinetic rate to modeling that effect k and n to modelisation that affects and obtained the impact of salinity content in the reaction medium (X and the acclimatization phase (Y on the kinetic constant (k = 0.097 e (-0.0003Yƒ{0.0346X and on the kinetic order (n = (0.0002Y-0.0195 X-0.009Y + 1.2382. Conclusion/Recommendations: Results from kinetic analysis allowed the prediction of the reaction rate and reaction yield with rather high accuracy, helping the design and operation of a biofilter under practical conditions.

  13. Diagnostics in biological rapid sand filters treating groundwater – governing factors for nitrification

    DEFF Research Database (Denmark)

    Albrechtsen, Hans-Jørgen; Gülay, Arda; Smets, Barth F.;

    To improve the insight in the processes in biological rapid sand filters a range of methods were developed to diagnose the microbial mediated processes – particularly nitrification.......To improve the insight in the processes in biological rapid sand filters a range of methods were developed to diagnose the microbial mediated processes – particularly nitrification....

  14. Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates.Biological occurrence of simultaneous nitrification and denitrifieation was verified in the aspect of nitrogen mass balance and alkalinity.The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate.In each experimental run the floe sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

  15. Nitrification inhibition as measured by RNA- and DNA-based function-specific assays and microbial community structure analyses

    Science.gov (United States)

    Abstract: The biological removal of ammonia in conventional wastewater treatment plants (WWTPs) is performed by promoting nitrification, which transforms ammonia into nitrate, which in turn is converted into nitrogen gas by denitrifying bacteria. The first step in nitrification, ...

  16. Disruption of narH, narJ, and moaE Inhibits Heterotrophic Nitrification in Pseudomonas Strain M19

    OpenAIRE

    Nemergut, D. R.; Schmidt, S. K.

    2002-01-01

    Interruptions in three nitrate reductase-related genes, narH, narJ, and moaE, inhibited heterotrophic nitrification in Pseudomonas strain M19. No nitrate was detected in the medium, and nitrification proceeded in the presence of a nitrate reductase inhibitor. Heterotrophic nitrification was greatly stimulated by the addition of nitrate.

  17. Copper deficiency can limit nitrification in biological rapid sand filters for drinking water production

    DEFF Research Database (Denmark)

    Wagner, Florian Benedikt; Nielsen, Peter Borch; Boe-Hansen, Rasmus;

    2016-01-01

    Incomplete nitrification in biological filters during drinking water treatment is problematic, as it compromises drinking water quality. Nitrification problems can be caused by a lack of nutrients for the nitrifying microorganisms. Since copper is an important element in one of the essential...... enzymes in nitrification, we investigated the effect of copper dosing on nitrification in different biological rapid sand filters treating groundwater. A lab-scale column assay with filter material from a water works demonstrated that addition of a trace metal mixture, including copper, increased ammonium...... removal compared to a control without addition. Subsequently, another water works was investigated in full-scale, where copper influent concentrations were below 0.05 μg Cu L-1 and nitrification was incomplete. Copper dosing of less than 5 μg Cu L-1 to a full-scale filter stimulated ammonium removal...

  18. Inhibition of nitrification by gamma irradiation in soil under plastic-house conditions

    International Nuclear Information System (INIS)

    An incubation experiment was conducted on sandy clay loam soil treated with ammonium sulfate to study the effect of gamma irradiation (100, 200, and 300 krad) and dicyandiamide (DCD, 5 and 10 ppm) as nitrification inhibitors during 12 weeks of incubation under plastichouse conditions. The nitrification process decreased by either gamma irradiation or DCD treatment of soil. In the soil treated with DCD, there were no significant differences between a concentration of 5 and 10 ppm during the period of incubation. In the soil irradiates with 300 krad, the nitrification rate was significantly lower compared with that in the DCD treatment at concentration of 5 and 10 ppm. Nitrification inhibition was low when the soil was subjected to gamma irradiation and DCD treatment during a period of 4 weeks but the inhibition increased after 6 weeks of incubation. (author)

  19. External and internal sources which inhibit the nitrification process in wastewater treatment plants

    DEFF Research Database (Denmark)

    Sinkjær, O.; Bøgebjerg, P.; Grüttner, Henrik;

    1996-01-01

    In connection with the upgrading of the two largest wastewater treatment plants in the Copenhagen area to nutrient removal special attention has been paid to the nitrification process regarding inhibition effects. Inhibitory substances in the wastewater could be identified by simple batch tests......, and the long-term effects on the nitrification process were tested in pilot plants or at full-scale. A distinction could be made between effects produced by wastewater from external sources in the catchment area and internally circulated flows in the wastewater treatment plant. Results from programmes...... the nitrification capacity monitored at the pilot plants has been in agreement with the design basis. The recycling of the scrubber water from the cleaning of sludge incineration flue gas was found to be an important internal source of inhibition at the Lynetten WWTP. Investigations show that it is...

  20. Effects of dynamic operating conditions on nitrification in biological rapid sand filters for drinking water treatment

    DEFF Research Database (Denmark)

    Lee, Carson Odell; Boe-Hansen, Rasmus; Musovic, Sanin;

    2014-01-01

    Biological rapid sand filters are often used to remove ammonium from groundwater for drinking water supply. They often operate under dynamic substrate and hydraulic loading conditions, which can lead to increased levels of ammonium and nitrite in the effluent. To determine the maximum nitrification...... full-scale filter. Nitrification rates and ammonia-oxidizing bacteria and archaea were quantified throughout the depth of the filter. The ammonium removal capacity of the filter was determined to be 3.4 g NH4–N m−3 h−1, which was 5 times greater than the average ammonium loading rate under reference...

  1. 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.

  2. Inhibition of the nitrification process in municipal wastewater treatment plants by industrial discharges

    DEFF Research Database (Denmark)

    Grüttner, Henrik; Winther-Nielsen, M.; Jorgensen, L.;

    1994-01-01

    More than three years of pilot-plant operation has documented that inhibition of nitrification was found to influence the dimensioning of the largest Danish wastewater treatment plant, which serves a major part of Copenhagen. Hence, a program for investigating the sources of substances inhibitory...... effects could be explained by the chemical substances in the wastewater from the industries. Based on the above described results, a strategy for control of the inhibitory effects at the different levels of the catchment area was suggested....

  3. The inhibition of marine nitrification by ocean disposal of carbon dioxide

    International Nuclear Information System (INIS)

    In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with pH values ranging from 6 to 8. In an effort to determine whether these CO2-induced pH changes have any effect on marine nitrification processes, surficial (euphotic zone) and deep (aphotic zone) seawater samples were sparged with CO2 for varying time durations to achieve a specified pH reduction, and the rate of microbial ammonia oxidation was measured spectrophotometrically as a function of pH using an inhibitor technique. For both seawater samples taken from either the euphotic or aphotic zone, the nitrification rates dropped drastically with decreasing pH. Relative to nitrification rates in the original seawater at pH 8, nitrification rates were reduced by ca. 50% at pH 7 and more than 90% at pH 6.5. Nitrification was essentially completely inhibited at pH 6. These findings suggest that the disposal of CO2 into mid or deep oceans will most likely result in a drastic reduction of ammonia oxidation rates within the pH plume and the concomitant accumulation of ammonia instead of nitrate. It is unlikely that ammonia will reach the high concentration levels at which marine aquatic organisms are known to be negatively affected. However, if the ammonia-rich seawater from inside the pH plume is upwelled into the euphotic zone, it is likely that changes in phytoplankton abundance and community structure will occur. Finally, the large-scale inhibition of nitrification and the subsequent reduction of nitrite and nitrate concentrations could also result in a decrease of denitrification rates which, in turn, could lead to the buildup of nitrogen and unpredictable eutrophication phenomena. Clearly, more research on the environmental

  4. Copper deficiency can limit nitrification in biological rapid sand filters for drinking water production.

    Science.gov (United States)

    Wagner, Florian B; Nielsen, Peter Borch; Boe-Hansen, Rasmus; Albrechtsen, Hans-Jørgen

    2016-05-15

    Incomplete nitrification in biological filters during drinking water treatment is problematic, as it compromises drinking water quality. Nitrification problems can be caused by a lack of nutrients for the nitrifying microorganisms. Since copper is an important element in one of the essential enzymes in nitrification, we investigated the effect of copper dosing on nitrification in different biological rapid sand filters treating groundwater. A lab-scale column assay with filter material from a water works demonstrated that addition of a trace metal mixture, including copper, increased ammonium removal compared to a control without addition. Subsequently, another water works was investigated in full-scale, where copper influent concentrations were below 0.05 μg Cu L(-1) and nitrification was incomplete. Copper dosing of less than 5 μg Cu L(-1) to a full-scale filter stimulated ammonium removal within one day, and doubled the filter's removal from 0.22 to 0.46 g NH4-N m(-3) filter material h(-1) within 20 days. The location of ammonium and nitrite oxidation shifted upwards in the filter, with an almost 14-fold increase in ammonium removal rate in the filter's top 10 cm, within 57 days of dosing. To study the persistence of the stimulation, copper was dosed to another filter at the water works for 42 days. After dosing was stopped, nitrification remained complete for at least 238 days. Filter effluent concentrations of up to 1.3 μg Cu L(-1) confirmed that copper fully penetrated the filters, and determination of copper content on filter media revealed a buildup of copper during dosing. The amount of copper stored on filter material gradually decreased after dosing stopped; however at a slower rate than it accumulated. Continuous detection of copper in the filter effluent confirmed a release of copper to the bulk phase. Overall, copper dosing to poorly performing biological rapid sand filters increased ammonium removal rates significantly, achieving effluent

  5. How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input.

    Science.gov (United States)

    Qiao, Chunlian; Liu, Lingli; Hu, Shuijin; Compton, Jana E; Greaver, Tara L; Li, Quanlin

    2015-03-01

    Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have doubled global annual reactive N inputs in the past 50-100 years, causing deleterious effects on the environment through increased N leaching and nitrous oxide (N2 O) and ammonia (NH3 ) emissions. Leaching and gaseous losses of N are greatly controlled by the net rate of microbial nitrification. Extensive experiments have been conducted to develop ways to inhibit this process through use of nitrification inhibitors (NI) in combination with fertilizers. Yet, no study has comprehensively assessed how inhibiting nitrification affects both hydrologic and gaseous losses of N and plant nitrogen use efficiency. We synthesized the results of 62 NI field studies and evaluated how NI application altered N cycle and ecosystem services in N-enriched systems. Our results showed that inhibiting nitrification by NI application increased NH3 emission (mean: 20%, 95% confidential interval: 33-67%), but reduced dissolved inorganic N leaching (-48%, -56% to -38%), N2 O emission (-44%, -48% to -39%) and NO emission (-24%, -38% to -8%). This amounted to a net reduction of 16.5% in the total N release to the environment. Inhibiting nitrification also increased plant N recovery (58%, 34-93%) and productivity of grain (9%, 6-13%), straw (15%, 12-18%), vegetable (5%, 0-10%) and pasture hay (14%, 8-20%). The cost and benefit analysis showed that the economic benefit of reducing N's environmental impacts offsets the cost of NI application. Applying NI along with N fertilizer could bring additional revenues of $163 ha(-1)  yr(-1) for a maize farm, equivalent to 8.95% increase in revenues. Our findings showed that NIs could create a win-win scenario that reduces the negative impact of N leaching and greenhouse gas production, while increases the agricultural output. However, NI's potential negative impacts, such as increase in NH3 emission and the risk of NI contamination, should be fully

  6. Effect of Hydraulic Retention Time on Nitrification in an AirLift Biological Reactor

    OpenAIRE

    Furtado A.A.L.; Albuquerque R.T.; Leite S.G.F.; Peçanha R.P.

    1998-01-01

    The occurrence of nitrogenous compounds in industrial effluents at concentration levels above legal limits, is a well-known and serious pollution problem for the receiving body. The biological process for the removal of these substances, commonly referred to as ammoniacal nitrogen, is known as nitrification. Bacteria involved are mainly of the genuses Nitrosomonas and Nitrobacter. The aim of the present work was to study the effect of the hydraulic retention time (HRT) on the efficiency of am...

  7. Chemical Inhibition of Nitrification: Evaluating Methods to Detect and Characterize Inhibition and the Role of Selected Stress Responses Upon Exposure to Oxidative and Hydrophobic Toxins

    OpenAIRE

    Kelly II, Richard Thomas

    2005-01-01

    This research first examined nitrification inhibition caused by different classes of industrially relevant chemicals on activated sludge and found that conventional aerobic nitrification was inhibited by single pulse inputs of every chemical tested, with 1-chloro-2,4-dinitrobenzene (oxidant) having the most severe impact, followed by alkaline pH 11, cadmium (heavy metal), cyanide, octanol (hydrophobic) and 2,4-dinitrophenol (respiratory uncoupler). Of the different chemicals tested, the oxid...

  8. Nitrification and microalgae cultivation for two-stage biological nutrient valorization from source separated urine.

    Science.gov (United States)

    Coppens, Joeri; Lindeboom, Ralph; Muys, Maarten; Coessens, Wout; Alloul, Abbas; Meerbergen, Ken; Lievens, Bart; Clauwaert, Peter; Boon, Nico; Vlaeminck, Siegfried E

    2016-07-01

    Urine contains the majority of nutrients in urban wastewaters and is an ideal nutrient recovery target. In this study, stabilization of real undiluted urine through nitrification and subsequent microalgae cultivation were explored as strategy for biological nutrient recovery. A nitrifying inoculum screening revealed a commercial aquaculture inoculum to have the highest halotolerance. This inoculum was compared with municipal activated sludge for the start-up of two nitrification membrane bioreactors. Complete nitrification of undiluted urine was achieved in both systems at a conductivity of 75mScm(-1) and loading rate above 450mgNL(-1)d(-1). The halotolerant inoculum shortened the start-up time with 54%. Nitrite oxidizers showed faster salt adaptation and Nitrobacter spp. became the dominant nitrite oxidizers. Nitrified urine as growth medium for Arthrospira platensis demonstrated superior growth compared to untreated urine and resulted in a high protein content of 62%. This two-stage strategy is therefore a promising approach for biological nutrient recovery. PMID:26998796

  9. Biological filter capable of simultaneous nitrification and denitrification for Aquatic Habitat in International Space Station

    Science.gov (United States)

    Uemoto, H.; Shoji, T.; Uchida, S.

    2014-04-01

    The biological filter capable of simultaneous nitrification and denitrification was constructed for aquatic animal experiments in the International Space Station (ISS). The biological filter will be used to remove harmful ammonia excreted from aquatic animals in a closed water circulation system (Aquatic Habitat). The biological filter is a cylindrical tank packed with porous glass beads for nitrification and dual plastic bags for denitrification. The porous beads are supporting media for Nitrosomonas europaea and Nitrobacter winogradskyi. The N. europaea cells and N. winogradskyi cells on the porous beads, oxidize the excreted ammonia to nitrate via nitrite. On the other hand, the dual bag is composed of an outer non-woven fabric bag and an inner non-porous polyethylene film bag. The outer bag is supporting media for Paracoccus pantotrophus. The inner bag, in which 99.5% ethanol is packed, releases the ethanol slowly, since ethanol can permeate through the non-porous polyethylene film. The P. pantotrophus cells on the outer bag reduce the produced nitrate to nitrogen gas by using the released ethanol as an electron donor for denitrification. The biological filter constructed in this study consequently removed the ammonia without accumulating nitrate. Most of the excess ethanol was consumed and did not affect the nitrification activity of the N. europaea cells and N. winogradskyi cells severely. In accordance with the aquatic animal experiments in the ISS, small freshwater fish had been bred in the closed water circulation system equipped with the biological filter for 90 days. Ammonia concentration daily excreted from fish is assumed to be 1.7 mg-N/L in the recirculation water. Under such conditions, the harmful ammonia and nitrite concentrations were kept below 0.1 mg-N/L in the recirculation water. Nitrate and total organic carbon concentrations in the recirculation water were kept below 5 mg-N/L and 3 mg-C/L, respectively. All breeding fish were alive and ate

  10. Distributions of inorganic nitrogen and biological production in the equatorial Pacific: a basin-scale model sensitivity study of nitrification

    Science.gov (United States)

    Wang, Xiujun; Murtugudde, Raghu

    2015-12-01

    Recent evidence indicates that there is stronger nitrification in the euphotic zone than previously thought. We employ a physical-biogeochemical model to study the implications of nitrification for basin-scale distributions of nitrate, ammonium, and biological production in the equatorial Pacific. The model can faithfully reproduce observed features in nitrate distribution, with or without photoinhibition of nitrification in the euphotic zone. In addition, new production, net community production and export production are not very sensitive to the parameterization of nitrification in this model. However, simulated ammonium distribution, nitrate uptake and ammonium uptake are sensitive to this parameterization. High nitrification results in low ammonium concentration, low ammonium uptake rate, and high nitrate uptake rate in the euphotic zone. This study suggests that nitrification may be responsible for up to 40% of nitrate uptake in the equatorial Pacific. This modeling study also demonstrates large differences (in terms of the magnitude and spatial distribution) between nitrate uptake, new production and export production, reflecting decoupling of upward nutrient supply, biological uptake and downward export.

  11. Relationships between root density of the African grass Hyparrhenia diplandra and nitrification at the decimetric scale: an inhibition-stimulation balance hypothesis.

    OpenAIRE

    Lata, J C; Guillaume, K; Degrange, V; Abbadie, L; Lensi, R

    2000-01-01

    Previous studies have shown that Lamto savannah exhibits two different types of nitrogen cycle with high and low nitrification sites and suggested that the perennial grass Hyparrhenia diplandra is responsible for this duality at a subpopulation level, with one ecotype being thought to be able to inhibit nitrification. The present work aimed to investigate the relationships between nitrification and the roots of H. diplandra at two scales. (i) Site-scale experiments gave new insight into the h...

  12. A novel bench-scale column assay to investigate site-specific nitrification biokinetics in biological rapid sand filters

    DEFF Research Database (Denmark)

    Tatari, Karolina; Smets, Barth F.; Albrechtsen, Hans-Jørgen

    2013-01-01

    A bench-scale assay was developed to obtain site-specific nitrification biokinetic information from biological rapid sand filters employed in groundwater treatment. The experimental set-up uses granular material subsampled from a full-scale filter, packed in a column, and operated with controlled....../m3 packed sand/h could easily be determined at 7.5 g NH4+–N/m3 packed sand/h. This assay, with conditions reflecting full-scale observations, and where the biological activity is subject to minimal physical disturbance, provides a simple and fast, yet powerful tool to gain insight in nitrification...

  13. Influence of physicochemical parameters of neem (Azadirachta indica A Juss) oils on nitrification inhibition in soil.

    Science.gov (United States)

    Kumar, Rajesh; Devakumar, C; Sharma, Vandana; Kakkar, Garima; Kumar, Dinesh; Panneerselvam, P

    2007-02-21

    The technology for the production of neem oil coated urea (NOCU) developed by the Indian Agricultural Research Institute is in the pipeline for adaption by several Indian fertilizer industries. Use of nitrification inhibitors is one of the methods of improving the nitrogen use efficiency (NUE) of nitrogenous fertilizers in agriculture. However, standard specifications for the neem oil as a raw material of NOCU are desired. Accordingly, the present study was undertaken to evaluate 25 samples of neem oils comprising 11 samples of expeller grade (EG) oils, 8 samples of cold-pressed (CP) oils, 3 samples of solvent-extracted oils, and 2 commercial formulations. NOCU was prepared using these oils (5000 ppm of urea-N). The soils fertilized with NOCUs (200 ppm of urea-N) were incubated at 27 degrees C and 50% water-holding capacity for a period of 15 days. Nitrapyrin (0.5% of N) coated urea served as the reference and prilled urea as control. Samples were analyzed for NH4+-N, NO2--N, and NO3--N using standard methods. The percent nitrification inhibition (NI) was calculated, and the results revealed that all of the neem oils caused NI ranging from 4.0 to 30.9%. Two samples of EG oils and two commercial formulations were found to be the best, causing 27.0-30.9% NI. Iodine, acid, and saponification values and meliacin content of all of the oils were analyzed and correlated with NI. The results revealed the direct influence of meliacin content of the neem oils on NI, which, however, was found to be negatively correlated with saponification and iodine values. There is, therefore, a need to introduce new Bureau of Indian Standards (BIS) specifications for neem oils as raw materials of NOCU. PMID:17263551

  14. Effect of Hydraulic Retention Time on Nitrification in an AirLift Biological Reactor

    Directory of Open Access Journals (Sweden)

    Furtado A.A.L.

    1998-01-01

    Full Text Available The occurrence of nitrogenous compounds in industrial effluents at concentration levels above legal limits, is a well-known and serious pollution problem for the receiving body. The biological process for the removal of these substances, commonly referred to as ammoniacal nitrogen, is known as nitrification. Bacteria involved are mainly of the genuses Nitrosomonas and Nitrobacter. The aim of the present work was to study the effect of the hydraulic retention time (HRT on the efficiency of ammonia removal from a petroleum refinery effluent using activated carbon particles as a biofilm support in an airlift bioreactor. The experiments were carried out using HRTs, equal to six, eight and ten hours. The results show that HRT equal to 8 and 10 hours were enough to reduce ammoniacal nitrogen concentration to levels below permited legal limits (5mg/L NH3-N. The reactor nitrifying performance was maximized at 85% removal of ammoniacal nitrogen, for a HRT equal to 10 hours.

  15. Modeling Nitrous Oxide Production during Biological Nitrogen Removal via Nitrification and Denitrification: Extensions to the General ASM Models

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Ruscalleda, Maël; Pellicer i Nàcher, Carles;

    2011-01-01

    Nitrous oxide (N2O) can be formed during biological nitrogen (N) removal processes. In this work, a mathematical model is developed that describes N2O production and consumption during activated sludge nitrification and denitrification. The well-known ASM process models are extended to capture N2...

  16. Trait-based representation of biological nitrification: Model development, testing, and predicted community composition

    Directory of Open Access Journals (Sweden)

    NickBouskill

    2012-10-01

    Full Text Available Trait-based microbial models show clear promise as tools to represent the diversity and activity of microorganisms across ecosystem gradients. These models parameterize specific traits that determine the relative fitness of an ‘organism’ in a given environment, and represent the complexity of biological systems across temporal and spatial scales. In this study we introduce a microbial community trait-based modeling framework (MicroTrait focused on nitrification (MicroTrait-N that represents the ammonia-oxidizing bacteria (AOB and ammonia-oxidizing archaea (AOA and nitrite oxidizing bacteria (NOB using traits related to enzyme kinetics and physiological properties. We used this model to predict nitrifier diversity, ammonia (NH3 oxidation rates and nitrous oxide (N2O production across pH, temperature and substrate gradients. Predicted nitrifier diversity was predominantly determined by temperature and substrate availability, the latter was strongly influenced by pH. The model predicted that transient N2O production rates are maximized by a decoupling of the AOB and NOB communities, resulting in an accumulation and detoxification of nitrite to N2O by AOB. However, cumulative N2O production (over six month simulations is maximized in a system where the relationship between AOB and NOB is maintained. When the reactions uncouple, the AOB become unstable and biomass declines rapidly, resulting in decreased NH3 oxidation and N2O production. We evaluated this model against site level chemical datasets from the interior of Alaska and accurately simulated NH3 oxidation rates and the relative ratio of AOA:AOB biomass. The predicted community structure and activity indicate (a parameterization of a small number of traits may be sufficient to broadly characterize nitrifying community structure and (b changing decadal trends in climate and edaphic conditions could impact nitrification rates in ways that are not captured by extant biogeochemical models.

  17. Nitrification and denitrification in biological activated carbon filter for treating high ammonia source water

    Institute of Scientific and Technical Information of China (English)

    Jianguang LIU; Xiaojian ZHANG; Zhansheng WANG

    2008-01-01

    Since the ammonia in the effluent of the tradi-tional water purification process could not meet the supply demand, the advanced treatment of a high concentration of NH4+-N micro-polluted source water by biological activated carbon filter (BACF) was tested. The filter was operated in the downflow manner and the results showed that the remov-ing rate of NH4+-N was related to the influent concentration of NH4+-N. Its removing rate could be higher than 95% when influent concentration was under 1.0 mg/L. It could also decrease with the increasing influent concentration when the NH4+-N concentration was in the range from 1.5-to 4.9 mg/L and the dissolved oxygen (DO) in the infuent was under 10 mg/L, and the minimum removing rate could be 30%. The key factor of restricting nitrifcation in BACF was the influent DO. When the influent NH4+-N concentration was high, the DO in water was almost depleted entirely by the nitrifying and hetetrophic bacteria in the depth of 0.4 m filter and the filter layer was divided into aerobic and anoxic zones. The nitrification and degradation of organic matters existed in the aerobic zone, while the denitrification occurred in the anoxic zone. Due to the limited carbon source, the denitrification could not be carried out properly, which led to the accu-mulation of the denitrification intermediates such as NO2-. In addition to the denitrification bacteria, the nitrification and the heterotrophic bacteria existed in the anoxic zone.

  18. How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input

    Science.gov (United States)

    We conducted a meta-analysis of 103 nitrification inhibitor (NI) studies, and evaluated how NI application affects crop productivity and other ecosystem services in agricultural systems. Our results showed that, compared to conventional fertilizer practice, applications of NI alo...

  19. Nitrification inhibition by hexavalent chromium Cr(VI)--Microbial ecology, gene expression and off-gas emissions.

    Science.gov (United States)

    Kim, Young Mo; Park, Hongkeun; Chandran, Kartik

    2016-04-01

    The goal of this study was to investigate the responses in the physiology, microbial ecology and gene expression of nitrifying bacteria to imposition of and recovery from Cr(VI) loading in a lab-scale nitrification bioreactor. Exposure to Cr(VI) in the reactor strongly inhibited nitrification performance resulting in a parallel decrease in nitrate production and ammonia consumption. Cr(VI) exposure also led to an overall decrease in total bacterial concentrations in the reactor. However, the fraction of ammonia oxidizing bacteria (AOB) decreased to a greater extent than the fraction of nitrite oxidizing bacteria (NOB). In terms of functional gene expression, a rapid decrease in the transcript concentrations of amoA gene coding for ammonia oxidation in AOB was observed in response to the Cr(VI) shock. In contrast, transcript concentrations of the nxrA gene coding for nitrite oxidation in NOB were relatively unchanged compared to Cr(VI) pre-exposure levels. Therefore, Cr(VI) exposure selectively and directly inhibited activity of AOB, which indirectly resulted in substrate (nitrite) limitation to NOB. Significantly, trends in amoA expression preceded performance trends both during imposition of and recovery from inhibition. During recovery from the Cr(VI) shock, the high ammonia concentrations in the bioreactor resulted in an irreversible shift towards AOB populations, which are expected to be more competitive in high ammonia environments. An inadvertent impact during recovery was increased emission of nitrous oxide (N2O) and nitric oxide (NO), consistent with recent findings linking AOB activity and the production of these gases. Therefore, Cr(VI) exposure elicited multiple responses on the microbial ecology, gene expression and both aqueous and gaseous nitrogenous conversion in a nitrification process. A complementary interrogation of these multiple responses facilitated an understanding of both direct and indirect inhibitory impacts on nitrification. PMID:26874778

  20. Nitrification in inland waters

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bollmann, A.; B. Ward, B.; J. Arp, D.; G. Klotz, M.

    2011-01-01

    Over the past 15 years, the use of modern molecular biological approaches has radically advanced our understanding of nitrification processes. With chapters contributed by leading experts in the field, Nitrification fully reviews all the latest research findings on microbes involved in conventional

  1. Inhibition of the Nitrification Process of Activated Sludge Micro-Organism by Scrubber Water from an Industrial Flue Gas Cleaning Process

    DEFF Research Database (Denmark)

    Thomsen, Jens Peter

    2007-01-01

    The microbial transformation of ammonia to nitrate, the nitrification, is a central process in the nitrogen biogeochemical cycle. In a modern wastewater treatment plant, the nitrification process is a key process in the removal of nitrogen and inhibitory compounds in sewage can seriously affect the...... nitrogen removal. A major sewage cleaning plant in the southern part of Denmark is a recipient of industrial sewage from a major fish meal industry. Severe nitrification inhibition was observed in scrubber water from an incineration of process air, and the processes that lead to the production were stopped...... using active sludge from the municipal wastewater cleaning plant. The investigation showed that it is possible to reduce the nitrification inhibition effect considerably by raising the incineration temperature from 800°C to 850°C and in some cases to 900°C. The investigation also showed that a further...

  2. Testing of Biologically Inhibiting Surface

    DEFF Research Database (Denmark)

    Bill Madsen, Thomas; Larsen, Erup

    2003-01-01

    The main purpose of this course is to examine a newly developed biologically inhibiting material with regards to galvanic corrosion and electrochemical properties. More in detail, the concern was how the material would react when exposed to cleaning agents, here under CIP cleaning (Cleaning In...

  3. Brachiaria species affecting soil nitrification

    OpenAIRE

    Adalton Mazetti Fernandes; Gabriel José Massoni de Andrade; Emerson de Freitas Cordova de Souza; Ciro Antonio Rosolem

    2011-01-01

    Nitrification can lead to substantial losses of the applied N through nitrate leaching and N2O emission. The regulation of nitrification may be a strategy to improve fertilizer N recovery and increase its agronomic efficiency. The objective of this study was to evaluate the inhibiting capacity of nitrification in soil by Brachiaria species. The greenhouse experiment was conducted using pots with 10 dm³ of a Red Latosol sample. The treatments consisted of the cultivation of three forage specie...

  4. Inhibition of the heavy metal nitrification process at the Granollers waste water treatment plant; Inhibicion del proceso de nitrificacion por metales pesados en le EDAR de Granollers

    Energy Technology Data Exchange (ETDEWEB)

    Serrano Jimenez, M.; Jorda LLona, J.; Rovira Gallejones, S.; Freixo Rey, A.; Polo Canas, P.

    2004-07-01

    Nowadays is habitual to find wastewater treatment plants with nutrient removal in which industrial wastes in collectors are capable of inhibiting the nitrification process. This article is about a procedure to follow when determining the origin of this inhibition in a WWTP and finding the best solution to the problem. Through discontinuous rests of AUR we find a strong intoxication of the WWTP activated sludge. A pilot plant is started with this sludge at laboratory level to be able to activate the process at a real plant level. A bio sorption process is started up by using activated sludge. The results of metal decrease in water and mixed liquor because of sludge washing are presented, as well as the increase in nitrification speed and other authors experience in metal adsorption by secondary sludge. (Author)

  5. Kinetic models for nitrogen inhibition in ANAMMOX and nitrification process on deammonification system at room temperature

    Science.gov (United States)

    The performance of the deammonification process depends on the microbial activity of ammonia oxidizing bacteria (AOB) and ANAMMOX bacteria. These autotrophic organisms have different preferences for substrate, operating conditions and some external factors that may cause inhibition or imbalance of t...

  6. Nitrification in Saline Industrial Wastewater

    NARCIS (Netherlands)

    Moussa, M.S.

    2004-01-01

    Biological nitrogen removal is widely and successfully applied for municipal wastewater. However, these experiences are not directly applicable to industrial wastewater, due to its specific composition. High salt levels in many industrial wastewaters affect nitrification negatively and improved unde

  7. Control strategy of shortcut nitrification

    Institute of Scientific and Technical Information of China (English)

    LU Gang; ZHENG Ping; JIN Ren-cun; QAISAR Mahmood

    2006-01-01

    Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed to study the combined effects of operational parameters on the performance of internal-loop airlift bioreactor for shortcut nitrification. The optimum operational parameters for the shortcut nitrification were found as temperature 35 ℃, pH 8.0, dissolved oxygen concentration 1.0 mg/L, ammonium concentration 4 mmol/L and HRT 16 h, which have different influence on the performance of shortcut nitrification reactor. The pH, temperature and dissolved oxygen concentration have significant bearing on the process. The results showed that the shortcut nitrification reactor could be successfully started up within 42 d, and the reactor performance is steady with minimum NO2-/NOx- of 85.2% , maximum 93.4% and average value of 91.4% in effluent. Based on the analysis of experimental data, a new control strategy named "priority + combination" for shortcut nitrification was suggested. Through this strategy, the startup and operation of shortcut nitrification for ammonium-rich sludge digester liquids were optimized. The control strategy works well to keep the reactor operation in steady state and in achieving high-efficiency for shortcut nitrification.

  8. The Potential For Efficient Biological Pre-Treatment Of Exploration Based Waste Streams For Potable Water Production Using A Membrane Reactor Capable Of Simultaneous Nitrification-Denitrification

    Science.gov (United States)

    Jackson, William; Morse, Audra; Landes, Nick

    Long term space habitation and exploration require high efficiency water recycling systems. Waste streams from space habitation contain high concentrations of both organic nitrogen and ammonium and high ratios of N to organic C compared to terrestrial wastewater. As with terrestrial systems wastewater must be highly treated to remove organic carbon, nitrogen compounds, salts, and trace constituents. In general, either some type of reverse osmosis or distillation step is required as the final treatment prior to disinfection. However, the high waste strength of the waste can seriously impact the efficiency of these post-processors. Biological pre-treatment is one process capable of significant reductions in organic carbon and nitrogen. Biological systems are self sustaining and require minimal inputs of energy or consumables. Research in our lab has been conducted to evaluate a number of micro-gravity compatible biological reactor systems. Both nitrification-denitrification coupled systems, in which oxygen consumption is reduced by using nitrate as an electron acceptor, and single reactor systems for organic removal and nitrification have been extensively investigated. Reactor types include tubular pulsed flow reactors, packed bed reactors, and membrane reactors. Recently a single vessel membrane reactor capable of simultaneous nitrification-denitrification (sNDN) has been developed and evaluated for its ability to potentially replace other proposed systems. Results to be presented include a review of past system performance and limitations with comparison to the performance of the new sNDN reactor system. Conversion efficiency, stability, and volumetric reaction rates will be discussed.

  9. Biological anoxic phosphorus removal in a continuous-flow external nitrification activated sludge system

    Energy Technology Data Exchange (ETDEWEB)

    Kapagiannidis, A. G.; Aivasidis, A.

    2009-07-01

    Application of Biological Nutrient Removal (BNR) process in wastewater treatment is necessitated for the protection of water bodies from eutrophication. an alternative BNR method is tested for simultaneous Carbon (C), Nitrogen (N) and Phosphorus (P) removal in a continuous-flow bench scale plant for municipal wastewater treatment. The plant operation is based on the activity of two microbial populations which grow under different operational conditions (two sludge system). (Author)

  10. Carbon removal and nitrification in a rotating biological contractor under different steady-state conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lowhorn, R.W. (Ben Cor Construction Co., Chattanooga, TN); Bustamante, R.B.; Bonner, W.P.

    1980-01-01

    The stage-by-stage degradation of soluble organics was monitored during waste water treatment. The effects of process parameters on nitration of waste water were determined. The rotating biological contactor, applying the fixed film prinicple, was used in this study. Parameters affecting nitrifying bacteria are: dissolved oxygen, temperature, pH, ammonia, nitrite, mean-cell retention time, organic matter, alkalinity, and rotational speed. It was shown that an increase in chemical oxygen demand can occur in the stages following heterotrophic activity in an RBC unit as a result of inadequate buffering capacity in waste water. (DMC)

  11. Archaeal Nitrification in Hot Springs

    Science.gov (United States)

    Richter, A.; Daims, H.; Reigstad, L.; Wanek, W.; Wagner, M.; Schleper, C.

    2006-12-01

    Biological nitrification, i.e. the aerobic conversion of ammonia to nitrate via nitrite, is a major component of the global nitrogen cycle. Until recently, it was thought that the ability to aerobically oxidize ammonia was confined to bacteria of the phylum Proteobacteria. However, it has recently been shown that Archaea of the phylum Crenarchaeota are also capable of ammonia oxidation. As many Crenarchaeota are thermophilic or hyperthermophilic, and at least some of them are capable of ammonia oxidation we speculated on the existence of (hyper)thermophilic ammonia-oxidizing archaea (AOA). Using PCR primers specifically targeting the archaeal ammonia monooxygenase (amoA) gene, we were indeed able to confirm the presence of such organisms in several hot springs in Reykjadalur, Iceland. These hot springs exhibited temperatures well above 80 °C and pH values ranging from 2.0 to 4.5. To proof that nitrification actually took place under these extreme conditions, we measured gross nitrification rates by the isotope pool dilution method; we added 15N-labelled nitrate to the mud and followed the dilution of the label by nitrate production from ammonium either in situ (incubation in the hot spring) or under controlled conditions in the laboratory (at 80 °C). The nitrification rates in the hot springs ranged from 0.79 to 2.22 mg nitrate-N per L of mud and day. Controls, in which microorganisms were killed before the incubations, demonstrated that the nitrification was of biological origin. Addition of ammonium increased the gross nitrification rate approximately 3-fold, indicating that the nitrification was ammonium limited under the conditions used. Collectively, our study provides evidence that (1) AOA are present in hot springs and (2) that they are actively nitrifying. These findings have major implications for our understanding of nitrogen cycling of hot environments.

  12. NITROGEN LOSSES DUE TO NITRIFICATION: PLANT BASED REMEDIAL PROSPECTS

    Directory of Open Access Journals (Sweden)

    Kavita Arora and Alka Srivastava*

    2013-06-01

    Full Text Available Nitrification of nitrogen fertilizers results into loss of nitrogen nutrient from soil along with environmental hazards, like, global warming, contamination of ground water and so on. To tackle the problem, many synthetic inhibitors of nitrification have been formulated but till now none of them has proved to be attractive option due to their cost and non-ecofriendly nature. A shift towards natural nitrification inhibitors would be beneficial, economically viable and environmentally safer option. Also, it is a matter of exhaustive research and appropriate testing before one can come out with infallible system with holistic integrated approach. To increase the potential of natural nitrification inhibitors, some neglected aspects, like, effect of genotypic variations, broader plant exploration for nitrification inhibition capacity, identification and isolation of secondary metabolites which are responsible for nitrification inhibition activity, manipulation of germplasm for superior nitrification inhibition performance require incessant persistent scientific input for transfer of information to the farmers.

  13. Biochar addition inhibiting nitrification of reclaimed soils in coal-mining subsidence area%施用生物炭抑制塌陷区复垦土壤硝化作用

    Institute of Scientific and Technical Information of China (English)

    朱继荣; 韦绪好; 祝鹏飞; 于红梅; 束良佐; 许志恒; 程德义

    2015-01-01

    transformation affected by biochar addition in soils with different fertility levels, especially in the extremely infertile reclaimed soil in the coal-mining subsidence area. In this paper, the effect of biochar addition on the nitrification in the reclaimed soil from a coal-mining subsidence area was examined by using a laboratory aerobic incubation method with constant temperature and controlled humidity under different nitrogen supply levels. In addition, vegetable soil with high fertility was used as the comparation. The experimental factors included three levels of biochar (0, 1.5%and 3%), two levels of nitrogen (at the rates of 200 and 400 mg/kg, respectively), and two kinds of soil (vegetable soil and reclaimed soil with extremely low fertility). In addition, soils without any biochar or nitrogen addition were cultured at the same condition to provide background nitrification information. Nitrate nitrogen and ammonium nitrogen concentration in soils were monitored during the cultivation period. The variation of nitrate nitrogen concentration in the cultivated soils was simulated by Logistic function and the significance values of the model were analyzed. It showed that, compared with the vegetable soil, the nitrification was slow in the reclaimed soil. The maximum rate of nitrification in the reclaimed soil was only 17.32% of that in the vegetable soil, and the time the maximum nitrification rate occurred delayed 4.2 days in the reclaimed soil compared with the vegetable soil. The inhibition of biochar addition on the nitrification was obvious especially in nitrification acceleration stage, and was affected interactively by nitrogen supply level and soil type. Compared with low nitrogen supply, biochar exerted greater inhibition on the nitrification so that the nitrification acceleration stage extended 6 days (for the reclaimed soil) or 11 days (for the vegetable soil) in the soil with high nitrogen supply. However, the nitrification acceleration stages were all

  14. Ammonium Uptake by Phytoplankton Regulates Nitrification in the Sunlit Ocean

    OpenAIRE

    Smith, Jason M.; Chavez, Francisco P.; Francis, Christopher A.

    2014-01-01

    Nitrification, the microbial oxidation of ammonium to nitrate, is a central part of the nitrogen cycle. In the ocean's surface layer, the process alters the distribution of inorganic nitrogen species available to phytoplankton and produces nitrous oxide. A widely held idea among oceanographers is that nitrification is inhibited by light in the ocean. However, recent evidence that the primary organisms involved in nitrification, the ammonia-oxidizing archaea (AOA), are present and active throu...

  15. Controlled Carbon Source Addition to an Alternating Nitrification-Denitrification Wastewater Treatment Process Including Biological P Removal

    DEFF Research Database (Denmark)

    Isaacs, Steven Howard; Henze, Mogens

    1995-01-01

    The paper investigates the effect of adding an external carbon source on the rate of denitrification in an alternating activated sludge process including biological P removal. Two carbon sources were examined, acetate and hydrolysate derived from biologically hydrolyzed sludge. Preliminary batch ...

  16. 复合生物反应器亚硝酸型同步硝化反硝化脱氮%Nitrogen Removal by Simultaneous Nitrification and Denitrification via Nitrite in a Sequence Hybrid Biological Reactor

    Institute of Scientific and Technical Information of China (English)

    王建龙; 彭永臻; 王淑莹; 高永青

    2008-01-01

    Sequence hybrid biological reactor(SHBR)was proposed,and some key control parameters were in-vestigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification(SND)via nitrite.sND via nitrite was achieved in SHBR by controlling demand oxygen(DO)concentration.There was a pro-did not destroy the partial nitrification to nitrite.The results showed that limited air flow rate to cause oxygen defi-ciency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate.Nitrogen removal efficiency was increased with the increase in NAR,that iS,NAR was increased from 60%to 90%,and total nitrogen removal efficiency was increased from 68%t0 85%.The SHBR could tolerate high organic loading rate(OLR),COD and ammonia-nitrogen removal efficiency were greater than92%and 93.5%respectively and it even oper-biofilm positively affected the activated sludge settling capability,and sludge volume index(svi)of activated sludge in SHBR never hit more than 90 ml.g-1 throughout the experiments.

  17. Effect of arsenic on nitrification of simulated mining water.

    Science.gov (United States)

    Papirio, S; Zou, G; Ylinen, A; Di Capua, F; Pirozzi, F; Puhakka, J A

    2014-07-01

    Mining and mineral processing of gold-bearing ores often release arsenic to the environment. Ammonium is released when N-based explosives or cyanide are used. Nitrification of simulated As-rich mining waters was investigated in batch bioassays using nitrifying cultures enriched in a fluidized-bed reactor (FBR). Nitrification was maintained at 100mg AsTOT/L. In batch assays, ammonium was totally oxidized by the FBR enrichment in 48 h. As(III) oxidation to As(V) occurred during the first 3h attenuating arsenic toxicity to nitrification. At 150 and 200mg AsTOT/L, nitrification was inhibited by 25%. Candidatus Nitrospira defluvii and other nitrifying species mainly colonized the FBR. In conclusion, the FBR enriched cultures of municipal activated sludge origins tolerated high As concentrations making nitrification a potent process for mining water treatment. PMID:24852647

  18. A New Approach for Biologically-Inhibiting Surfaces

    DEFF Research Database (Denmark)

    Møller, Per; Hilbert, Lisbeth Rischel; Corfitzen, Charlotte B.;

    2007-01-01

    A biologically-inhibiting surface based on electrochemical principles has been shown to have a reducing effect on the formation of biofilms in drinking water. The coating consists of silver and another precious metal, which is applied to the surface in small areas with a thickness measured in...... nanometers. Due to the difference in potentials, the biologically-inhibiting material will act as a galvanic element in contact with an electrolyte. The electrochemical processes taking place at the metal surface seem to exhibit a catalytic oxidation character more than an oligomeric effect from the silver....

  19. Nitrification in four acidic streams in southern New Jersey

    Science.gov (United States)

    Schornick, James C., Jr.; Ram, Neil M.

    1978-01-01

    Four characteristically acidic streams in southern New Jersey were investigated to determine the effect of secondary effluent on nitrification in the receiving waters. Chemical and microbiological data were obtained at four sites on each stream. From these data seven factors were evaluated to determine the proclivity of each stream to nitrify. pH, water temperature, and dissolved oxygen were used to describe the general condition of the streams, while neutralization of alkalinity, nitrogen species concentration trends, biological and nitrogenous oxygen demand incubations, and nitrifying bacteria densities were used to determine the actual presence of nitrification in each stream. Each stream had a unique distribution of conditions, making it possible to qualitatively rank the streams according to their proclivity to nitrify. Hay StackBrook showes strong evidence for nitrification on the basis of all four nitrification indicators, whereas Landing Creek showed little, if any, evidence of nitrification. Hammonton Creek is apparently nitrifying, but because of the uncertainty in the downstream trends of the nitrogen species and a lower level of alkalinity neutralization, it is nitrifying less than Hay Stack Brook. Squankum Branch also showed some evidence for nitrification, mostly on the basis of the biological and nitrogenous oxygen demand incubations. Although these streams are acidic in character, acidity does not appear to be an exclusive factor in determining whether a stream will undergo nitrification. (Woodard-USGS)

  20. From Partial nitrification to canon in an aerobic granular SBR

    International Nuclear Information System (INIS)

    Nitrogen removal via nitrification-denitrification processes is commonly used in biology wastewater treatment plants to remove nitrogen compounds. In recent years new technologies emerged bringing solutions to remove nitrogen from wastewaters with not enough COD content to complete the denitrification process. An alternative strategy to the conventional nitrification-denitrification processes has been developed in the nine tries consisting of a combination of the oxidation of half of the ammonium from the wastewater to nitrite via partial nitrification and the removal of both, ammonium and formed nitrite by the Anammox process. (Author)

  1. Some plant extracts retarde nitrification in soil

    Directory of Open Access Journals (Sweden)

    Abdul–Mehdi S. AL-ANSARI

    2015-12-01

    Full Text Available An incubation experiment was conducted to evaluate the effect of aqueous extracts of 17 plant materials on nitrification inhibition of urea- N in soil as compared with chemical inhibitor Dicyandiamide (DCD. Plant materials used in study were collected from different areas of Basrah province, south of Iraq. Aqueous extracts were prepared at ratio of 1:10 (plant material: water and added at conc. of 0.05, 0.10 and 0.20 ml g– 1 soil to loamy sand soil. DCD was added to soil at rate of 50 µg g-1 soil . Soil received urea at rate of 1000 µg N g-1 soil. Treated soils were incubated at 30 OC for 40 days. Results showed that application of all plant extracts, except those of casuarina, date palm and eucalyptus to soil retarded nitrification in soil. Caper, Sowthistle ,bladygrass and pomegranate extracts showed highest inhibition percentage (51, 42, 40 and 40 %, respectively and were found to be more effective than DCD (33 %. Highest inhibition was achieved by using those extracts at conc. of 0.1 ml g-1 soil after 10 days of incubation . Data also revealed that treated soil with these plant extracts significantly increased amount of NH4+–N and decreased amount of NO3-–N accumulation in soil compared with DCD and control treatments. Results of the study suggested a possibility of using aqueous extracts of some studied plants as potent nitrification inhibitor in soil.

  2. Multistage treatment system for raw leachate from sanitary landfill combining biological nitrification-denitrification/solar photo-Fenton/biological processes, at a scale close to industrial--biodegradability enhancement and evolution profile of trace pollutants.

    Science.gov (United States)

    Silva, Tânia F C V; Silva, M Elisabete F; Cunha-Queda, A Cristina; Fonseca, Amélia; Saraiva, Isabel; Sousa, M A; Gonçalves, C; Alpendurada, M F; Boaventura, Rui A R; Vilar, Vítor J P

    2013-10-15

    A multistage treatment system, at a scale close to the industrial, was designed for the treatment of a mature raw landfill leachate, including: a) an activated sludge biological oxidation (ASBO), under aerobic and anoxic conditions; b) a solar photo-Fenton process, enhancing the bio-treated leachate biodegradability, with and without sludge removal after acidification; and c) a final polishing step, with further ASBO. The raw leachate was characterized by a high concentration of humic substances (HS) (1211 mg CHS/L), representing 39% of the dissolved organic carbon (DOC) content, and a high nitrogen content, mainly in the form of ammonium nitrogen (>3.8 g NH4(+)-N/L). In the first biological oxidation step, a 95% removal of total nitrogen and a 39% mineralization in terms of DOC were achieved, remaining only the recalcitrant fraction, mainly attributed to HS (57% of DOC). Under aerobic conditions, the highest nitrification rate obtained was 8.2 mg NH4(+)-N/h/g of volatile suspended solids (VSS), and under anoxic conditions, the maximum denitrification rate obtained was 5.8 mg (NO2(-)-N + NO3(-)-N)/h/g VSS, with a C/N consumption ratio of 2.4 mg CH3OH/mg (NO2(-)-N + NO3(-)-N). The precipitation of humic acids (37% of HS) after acidification of the bio-treated leachate corresponds to a 96% DOC abatement. The amount of UV energy and H2O2 consumption during the photo-Fenton reaction was 30% higher in the experiment without sludge removal and, consequently, the reaction velocity was 30% lower. The phototreatment process led to the depletion of HS >80%, of low-molecular-weight carboxylate anions >70% and other organic micropollutants, thus resulting in a total biodegradability increase of >70%. The second biological oxidation allowed to obtain a final treated leachate in compliance with legal discharge limits regarding water bodies (with the exception of sulfate ions), considering the experiment without sludge. Finally, the high efficiency of the overall treatment

  3. Nitrification dynamics in soil due to variation in Co 2 level

    OpenAIRE

    HAROON SHAHZAD; MUHAMMAD IQBAL; ATIF JAVED; SARVET JEHAN

    2015-01-01

    Nitrification process in the soil is oxidation reaction that occurs in aerobic environment. Under anaerobic environment reduced conditions prevails inhibiting nitrification process. A lab incubation study was designed to assess the effect of CO 2 level on nitrification in soil. Soil samples were taken in container and incubated for two weeks under conditions, (i) 0, 1 and 2% ground farm manure mixed with soil and (ii) with and without KOH solution to trap CO 2. Each of the treatment was repli...

  4. Dicyandiamide as nitrification inhibitor of pig slurry ammonium nitrogen in soil

    OpenAIRE

    Rogério Gonzatto; Fernanda Stüker; Celso Aita; Sandro José Giacomini; Roberto Carlos Lüdtke; Alexandre Dessbesell; Diego Antonio Giacomini; Stefen Barbosa Pujol

    2016-01-01

    ABSTRACT: Inhibition of nitrification of ammoniacal nitrogen pig slurry after its application to the soil can mitigate nitrogen (N) losses by nitrate (NO3 -) denitrification and leaching, with economical and environmental benefits. However, the use of this strategy is incipient in Brazil and, therefore, requires further assessment. The aim of this study was to evaluate the efficiency of dicyandiamide (DCD) nitrification inhibitor in slowing the nitrification of ammoniacal N applied to the soi...

  5. Nitrification in Kochi backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Miranda, J.; Balachandran, K.K.; Ramesh, R.; Wafar, M.

    , were measured in Kochi back- 166 nmol N L C01 h C01 in the water column and up to 17 nmol N (g wet (2008) 291e300 www.elsevier.com/locate/ecss and receive also untreated sewage (260 m 3 day C01 ) from Kochi city (Balachandran et al., 2005), besides... in the relation between salinity and nitrification in non- monsoon months where lowest rates at lowest salinities Shelf Science 78 (2008) 291e300 increased to highest rates at intermediate salinities. At higher salinities, the nitrifying activity actually...

  6. Complete nitrification by Nitrospira bacteria

    DEFF Research Database (Denmark)

    Daims, Holger; Lebedeva, Elena V.; Pjevac, Petra;

    2015-01-01

    Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetic...

  7. [Regulation of soil nitrification with nitrification inhibitors and related mechanisms].

    Science.gov (United States)

    Sun, Zhi-Mei; Wu, Zhi-Jie; Chen, Li-Jun; Jia, Li-Bin

    2008-06-01

    To improve the use efficiency of fertilizer N while alleviate its pollution is one of the keys in ensuring the high yield and good quality of agricultural products and the sustainable development of agriculture and environment, for which, applying nitrification inhibitors to retard the course of soil nitrification is an efficient measure. In this review, the definition, screening criteria, major varieties being widely used, and action mechanisms of nitrification inhibitors were introduced, and the existing problems and prospects in related researches were discussed. PMID:18808037

  8. Effects of lignin on nitrification in soil

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The effects of two lignins isolated from black liquor from pulping process on nitrification in soils after addition of urea, (NH4)2SO4 and (NH4)2HPO4 were investigated by incubation at 20 or 30℃ for 7 or 14d. The effects of lignin on nitrous oxide emissions from soil were also determined. Results showed that both lignins were more effective for inhibiting nitrification of NH4+-N as (NH4)2SO4 or (NH4)2HPO4 as compared to urea-N. The effectiveness of lignin on nitrification was markedly affected by different soil type and temperature. Nitrous oxide emissions from soil declined when lignin was used. Urea plus 20 and 50 g/kg lignin reduced N2O emissions by about 83% and 96%, respectively, while (NH4)2HPO4 plus 20 and 50 g/kg lignin respectively reduced emissions by 83% and 93%. Because of its low cost and nonhazardous characteristics, lignin has potential value as a fertilizer amendment to improve N fertilizer efficiency.

  9. Effects of organic nitrification inhibitors on methane and nitrous oxide emission from tropical rice paddy

    Science.gov (United States)

    Datta, A.; Adhya, T. K.

    2014-08-01

    We have studied the effects of application of different nitrification inhibitors on methane (CH4) and nitrous oxide (N2O) emissions from rice paddy and associated soil chemical and biological dynamics during wet and dry seasons of rice crop in a tropical climate of eastern India. The experiment consisted of four treatments viz. (i) Prilled urea amended control (ii) urea + Dicyandiamide (DCD), (iii) urea + Nimin and (iv) urea + Karanjin. CH4 emission was significantly higher from the DCD (372.36 kg ha-1) and Karanjin (153.07 kg ha-1) applied plots during the wet and dry season, respectively. N2O emission was significantly inhibited in the Nimin applied plots during both seasons (69% and 85% over control during wet season and dry season respectively). CH4 and N2O emissions per Mg of rice grain yield were lowest from the Nimin applied plots during both seasons. Global warming potential (GWP) of the plot treated with DCD (13.93) was significantly higher during the experimental period. CH4 production potential was significantly higher from the nitrification inhibitor applied plots compared to control. While, CH4 oxidation potential followed the order; urea + Nimin > urea + Karanjin > urea + DCD > control. Application of Nimin significantly increased the methanotrophic bacterial population in the soil during the maximum tillering to flowering stage and may be attributed to low CH4 emission from the plots. Denitrification enzyme activity (DEA) of the soil was significantly low from the Nimin and Karanjin applied plots. Results suggest that apart from being potent nitrification inhibitors, Nimin and Karanjin also have the potential to reduce the denitrification activity in the soil. This in turn, would reduce N2O emission from flooded paddy where both nitrification and denitrification processes causes N2O emission.

  10. Nitrification and denitrification as sources of gaseous nitrogen emission from different forest soils in Changbai Mountain

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The contributions of nitrification and denitrification to N2O and N2 emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C2H2 were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N2O > Nitrification N2O > Denitrification N2. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N2O > Denitrification N2.

  11. Automatic set-point titration for monitoring nitrification in SBRs.

    Science.gov (United States)

    Fiocchi, N; Ficara, E; Bonelli, S; Canziani, R; Ciappelloni, F; Mariani, S; Pirani, M; Ratini, P; Mazouni, D; Harmand, J

    2008-01-01

    Nitrification is usually the bottleneck of biological nitrogen removal processes. In SBRs systems, it is not often enough to monitor dissolved oxygen, pH and ORP to spot problems which may occur in nitrification processes. Therefore, automated supervision systems should be designed to include the possibility of monitoring the activity of nitrifying populations. Though the applicability of set-point titration for monitoring biological processes has been widely demonstrated in the literature, the possibility of an automated procedure is still at its early stage of industrial development. In this work, the use of an at-line automated titrator named TITAAN (TITrimetric Automated ANalyser) is presented. The completely automated sensor enables us to track nitrification rate trend with time in an SBR, detecting the causes leading to slower specific nitrification rates. It was also possible to perform early detection of toxic compounds in the influent by assessing their effect on the nitrifying biomass. Nitrifications rates were determined with average errors+/-10% (on 26 tests), never exceeding 20% as compared with UV-spectrophotometric determinations. PMID:18701782

  12. Influence of Biological Macromolecules and Aquatic Chemistries on the Inhibition of Nitrifying Bacteria by Silver Nanoparticles

    Science.gov (United States)

    Radniecki, T. S.; Anderson, J. W.; Schneider, M. C.; Stankus, D. P.; Nason, J. A.; Semprini, L.

    2010-12-01

    The use of silver nanoparticles (Ag-NP) as a broad spectrum biocide in a wide range of consumer goods has grown exponentially since 2006 (1), which may result in an increased release of Ag-NP into wastewater streams and ultimately the receiving bodies of water. Ammonia oxidizing bacteria (AOB) play a critical role in the global nitrogen cycle through the oxidation of ammonia (NH3) to nitrite (NO2-) and are widely considered to be the most sensitive microbial fauna in the environment being readily inhibited by contaminants, including Ag-NP (2). This research used physiological techniques in combination with physical/chemical assays to characterize the inhibition of Nitrosomonas europaea, the model AOB, by silver ions (Ag+), 3-5 nm Ag-NP, 20 nm Ag-NP and 80 nm Ag-NP under a variety of aqueous chemistries. In addition, the stability of Ag-NP suspensions was examined under a variety of aqueous chemistries including in the presences of divalent cations, chloride anions, natural organic matter (NOM), proteins (BSA) and lipopolysaccharides (alginate). Using the stable Ag-NP/test media suspensions, N. europaea was found to be extremely sensitive to Ag+, 3-5 nm Ag-NP, 20 nm Ag-NP and 80 nm Ag-NP with concentrations of 0.1, 0.12, 0.5 and 1.5 ppm, respectively, resulting in a 50% decrease in nitrification rates. The inhibition was correlated with the amount of Ag+ released into solution. It is suspected that the inhibition observed from Ag-NP exposure is caused by the liberated Ag+. The aquatic chemistry of the test media was found to have a profound influence on the stability of Ag-NP suspensions. The presence of Ag ligands (e.g. EDTA and Cl-) reduced toxicity of Ag-NP through the formation of Ag-ligand complexes with the liberated Ag+. The presence of divalent cations (e.g. Ca2+ or Mg2+) resulted in the rapid aggregation of Ag-NP leading to a decrease in Ag+ liberation and thus a decrease in N. europaea inhibition. The presence of 5 ppm NOM resulted in a highly stable Ag

  13. Distinguishing between Nitrification and Denitrification as Sources of Gaseous Nitrogen Production in Soil †

    OpenAIRE

    Davidson, Eric A.; Swank, Wayne T.; Perry, Thomas O.

    1986-01-01

    The source of N2O produced in soil is often uncertain because denitrification and nitrification can occur simultaneously in the same soil aggregate. A technique which exploits the differential sensitivity of these processes to C2H2 inhibition is proposed for distinguishing among gaseous N losses from soils. Denitrification N2O was estimated from 24-h laboratory incubations in which nitrification was inhibited by 10-Pa C2H2. Nitrification N2O was estimated from the difference between N2O produ...

  14. Effect of Lanthanum on Nitrification, Phosphorus Transformation and Phenol Decomposition in Red Soil

    Institute of Scientific and Technical Information of China (English)

    褚海燕; 朱建国; 谢祖彬; 李振高; 曹志洪; 曾青

    2002-01-01

    The effect of La on nitrification, P transformation and phenol decomposition in red soil was studied by incubation and pot culture experiments. La at low concentration has stimulative effect on soil nitrification and P transformation while its high concentration has inhibitory effects, and the inhibition is strengthened with increasing concentration of La. La has strongly inhibitory effect on soil phenol decomposition and the inhibition is strengthened with increasing concentration of La. When the incubation time is prolonged, the inhibitory effect of La on soil nitrification and phenol decomposition tends to decrease.

  15. Activating and inhibiting connections in biological network dynamics

    Directory of Open Access Journals (Sweden)

    Knight Rob

    2008-12-01

    Full Text Available Abstract Background Many studies of biochemical networks have analyzed network topology. Such work has suggested that specific types of network wiring may increase network robustness and therefore confer a selective advantage. However, knowledge of network topology does not allow one to predict network dynamical behavior – for example, whether deleting a protein from a signaling network would maintain the network's dynamical behavior, or induce oscillations or chaos. Results Here we report that the balance between activating and inhibiting connections is important in determining whether network dynamics reach steady state or oscillate. We use a simple dynamical model of a network of interacting genes or proteins. Using the model, we study random networks, networks selected for robust dynamics, and examples of biological network topologies. The fraction of activating connections influences whether the network dynamics reach steady state or oscillate. Conclusion The activating fraction may predispose a network to oscillate or reach steady state, and neutral evolution or selection of this parameter may affect the behavior of biological networks. This principle may unify the dynamics of a wide range of cellular networks. Reviewers Reviewed by Sergei Maslov, Eugene Koonin, and Yu (Brandon Xia (nominated by Mark Gerstein. For the full reviews, please go to the Reviewers' comments section.

  16. Effects of polychlorinated biphenyls and environmental biotransformation products on aquatic nitrification.

    OpenAIRE

    Sayler, G S; Shiaris, M. P.; Beck, W.; Held, S.

    1982-01-01

    The effects of polychlorinated biphenyls (PCBs) on nitrification were examined for pure cultures and natural reservoir samples. PCBs at concentrations greater than 10 microgram liter-1 inhibited nitrification, principally ammonium oxidation, in one of two natural reservoir environments. However, this inhibition could not be reproduced in pure high-cell-density cultures or in previously contaminated reservoir waters. A PCB environmental biotransformation product, p-chlorophenylglyoxylic acid, ...

  17. Complete nitrification by Nitrospira bacteria.

    Science.gov (United States)

    Daims, Holger; Lebedeva, Elena V; Pjevac, Petra; Han, Ping; Herbold, Craig; Albertsen, Mads; Jehmlich, Nico; Palatinszky, Marton; Vierheilig, Julia; Bulaev, Alexandr; Kirkegaard, Rasmus H; von Bergen, Martin; Rattei, Thomas; Bendinger, Bernd; Nielsen, Per H; Wagner, Michael

    2015-12-24

    Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetically advantageous. This functional separation has puzzled microbiologists for a century. Here we report on the discovery and cultivation of a completely nitrifying bacterium from the genus Nitrospira, a globally distributed group of nitrite oxidizers. The genome of this chemolithoautotrophic organism encodes the pathways both for ammonia and nitrite oxidation, which are concomitantly activated during growth by ammonia oxidation to nitrate. Genes affiliated with the phylogenetically distinct ammonia monooxygenase and hydroxylamine dehydrogenase genes of Nitrospira are present in many environments and were retrieved on Nitrospira-contigs in new metagenomes from engineered systems. These findings fundamentally change our picture of nitrification and point to completely nitrifying Nitrospira as key components of nitrogen-cycling microbial communities. PMID:26610024

  18. 运行方式对曝气生物滤池实现短程硝化的影响%Effect of Operational Modes on Shortcut Nitrification in Biological Aerated Filter

    Institute of Scientific and Technical Information of China (English)

    梅翔; 占晶; 谢玥; 蒋飞; 马耀进

    2011-01-01

    In order to investigate the effect of operational modes on shortcut nitrification in a biological aerated filter for treatment of ammonia nitrogen wastewater, three operational modes including continuous influent with alternating aeration, influent with aeration and no influent without aeration, and influent without aeration and no influent with aeration were carried out. Moreover, in the case of continuous influent with alternating aeration, the performances of the biological aerated filter were investigated at three time phase ratios of aeration to no aeration, which were 4:4,5:3 and 2 : 2 : 2 : 2. The experimental results show that the nitrite accumulation rate of more than 90% and the ammonia nitrogen removal rate of more than 70% can be achieved and maintained under the condition of continuous influent with alternating aeration, with influent ammonia nitrogen of 53 to 101 mg/L, temperature of 33 ℃ , HRT of 8 h, air to water ratio of 22.7 and aeration to no aeration ratio of 5 : 3. This research indicates that the biological aerated filter can realize shortcut nitrification with a higher ammonia nitrogen removal rate and a higher nitrite accumulation rate via controlling the operational modes.%为研究曝气生物滤池处理氨氮废水时运行方式对实现短程硝化的影响,进行了连续进水交替曝气、进水曝气停水停气和进水停气停水曝气3种运行方式试验,并考察了连续进水交替曝气条件下3种不同交替曝气时段分配比例,即曝气:停气分别为(4∶4)、(5∶3)、(2∶2∶2∶2)对系统运行效果的影响.结果表明,在连续进水交替曝气条件下,当进水氨氮为53 ~ 101 mg/L、温度为33℃、水力停留时间为8h、气水比为22.7、交替曝气时段分配比例为5:3时可实现并维持90%以上的亚硝酸盐氮积累率,此时对氨氮的去除率也在70%以上.研究表明,通过调控运行方式可较好地实现曝气生物滤池的短程硝化,并获得较高的氨

  19. Effects of Cr(III) and CR(VI) on nitrification inhibition as determined by SOUR, function-specific gene expression and 16S rRNA sequence analysis of wastewater nitrifying enrichments

    Science.gov (United States)

    The effect of Cr(III) and Cr(VI) on ammonia oxidation, the transcriptional responses of functional genes involved in nitrification and changes in 16S rRNA level sequences were examined in nitrifying enrichment cultures. The nitrifying bioreactor was operated as a continuous react...

  20. Nitrification in Dutch heathland soils.

    NARCIS (Netherlands)

    Boer, de W.

    1989-01-01

    This thesis is the result of a study on the production of nitrate in Dutch heathland soils. Most of the heathlands are located on acid, sandy soils. Therefore , it has dealt mainly with the occurrence, nature and mechanisms of nitrification in acid soils. In the Netherlands, the production of nitrat

  1. Archaeal nitrification in the ocean

    NARCIS (Netherlands)

    Wuchter, C.; Abbas, B.; Coolen, M.J.L.; Herfort, L.; Bleijswijk, J. van; Timmers, P.; Strous, M.; Teira, E.; Herndl, G.J.; Middelburg, J.J.; Schouten, S.; Sinninghe Damsté, J.S.

    2006-01-01

    Marine Crenarchaeota are the most abundant single group of prokaryotes in the ocean, but their physiology and role in marine biogeochemical cycles are unknown. Recently, a member of this clade was isolated from a sea aquarium and shown to be capable of nitrification, tentatively suggesting that Cren

  2. Dicyandiamide as nitrification inhibitor of pig slurry ammonium nitrogen in soil

    Directory of Open Access Journals (Sweden)

    Rogério Gonzatto

    2016-05-01

    Full Text Available ABSTRACT: Inhibition of nitrification of ammoniacal nitrogen pig slurry after its application to the soil can mitigate nitrogen (N losses by nitrate (NO3 - denitrification and leaching, with economical and environmental benefits. However, the use of this strategy is incipient in Brazil and, therefore, requires further assessment. The aim of this study was to evaluate the efficiency of dicyandiamide (DCD nitrification inhibitor in slowing the nitrification of ammoniacal N applied to the soil with pig slurry (PS. For this, incubation was performed in laboratory, where nitrification was assessed by NO3 - accumulation in the soil. Rates of 2.8, 5.7 and 11.3kg DCD ha-1 were compared, being applied to the soil during PS addition. Nitrification was inhibited by DCD, and inhibition magnitude and duration depended on DCD applied rate. At a dose of 11.3kg ha-1 DCD, nitrification was completely inhibited in the first 12 days. During the first month after PS application, each 2.8kg of DCD increase applied per hectare promoted NO3 --N reduction in the soil of 13.3kg ha-1, allowing longer ammoniacal N maintenance in the soil.

  3. Effect of Volatile Fatty Acids and Trimethylamine on Nitrification in Activated Sludge

    DEFF Research Database (Denmark)

    Eilersen, Ann Marie; Henze, Mogens; Kløft, Lene

    1994-01-01

    The effect of volatile fatty acids and trimethylamine on the nitrification activity of activated sludge was studied in laboratory batch experiments. The critical concentration of inhibitor IK at which the activity ceases was determined by modelling. IK values for ammonia oxidation were found to be...... wastewater stripped of sulphide showed that volatile fatty acids and trimethylamine alone cannot account for the inhibition of the nitrification activity, indicating that other factors are also involved....

  4. Nitrification and Autotrophic Nitrifying Bacteria in a Hydrocarbon-Polluted Soil

    OpenAIRE

    Deni, Jamal; Penninckx, Michel J.

    1999-01-01

    In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate bu...

  5. Nitrification Inhibitors: A Perspective Tool to Mitigate Greenhouse Gas Emissions from Rice Soils

    Directory of Open Access Journals (Sweden)

    Sandeep K. Malyan

    2016-08-01

    Full Text Available Rice fields are significant contributors of greenhouse gases mainly methane and nitrous oxide to the atmosphere. Increasing concentrations of these greenhouse gases play significant role in changing atmospheric chemistry such as mean air temperature, rainfall pattern, drought, and flood frequency. Mitigation of greenhouse gases for achieving sustainable agriculture without affecting economical production is one the biggest challenge of twenty first century at national and global scale. On the basis of published scientific studies, we hereby assess the use of nitrification inhibitors for greenhouse gas mitigation from rice soil. Biologically oxidation of ammonium to nitrate is termed as nitrification and materials which suppress this process are known as nitrification inhibitors. Soil amendment by addition of certain nitrification inhibitors such as neem oil coated urea, nimin-coated urea; dicyandiamide, encapsulated calcium carbide, and hydroquinone reduce cumulative methane and nitrous oxide emission from rice. Firstly, these inhibitors reduce nitrous oxide emissions both directly by nitrification (by reducing NH4+ to NO3- as well as indirectly by de-nitrification (by reducing NO3- availability in soil. Secondly, methane emission from rice soil can be reduced by enhancing methane oxidation and suppressing methane production and further by reducing the aerenchymal transportation through rice plant. Application of some of the nitrification inhibitors such as calcium carbide and encapsulated calcium carbide reduce methane production by releasing acetylene gas which helps in reducing the population of methanogenic microbes in the soil. Application of nitrification inhibitors also helps to maintain soil redox potential at higher level subsequently reducing cumulative methane emission from soil. Plant derived organic nitrification inhibitors (neem oil, neem cake, karanja seed extract are eco-friendly and possess substantial greenhouse gas mitigation

  6. Nitrification at Low pH by Aggregated Chemolithotrophic Bacteria

    OpenAIRE

    De Boer, W.; Klein Gunnewiek, P.J.A.; Veenhuis, M; Bock, E; Laanbroek, H. J.

    1991-01-01

    A study was performed to gain insight into the mechanism of acid-tolerant, chemolithotrophic nitrification. Microorganisms that nitrified at pH 4 were enriched from two Dutch acid soils. Nitrate production in the enrichment cultures was indicated to be of a chemolithoautotrophic nature as it was (i) completely inhibited by acetylene at a concentration as low as 1-mu-mol/liter and (ii) strongly retarded under conditions of carbon dioxide limitation. Electron microscopy of the enrichment cultur...

  7. Archaeal nitrification in the ocean

    OpenAIRE

    Wuchter, C.; Abbas, B.; M J L Coolen; Herfort, L.; van Bleijswijk, J.; Timmers, P.; Strous, M.; E. Teira; Herndl, G. J.; Middelburg, J. J.; Schouten, S; Sinninghe Damsté, J.S.

    2006-01-01

    Marine Crenarchaeota are the most abundant single group of prokaryotes in the ocean, but their physiology and role in marine biogeochemical cycles are unknown. Recently, a member of this clade was isolated from a sea aquarium and shown to be capable of nitrification, tentatively suggesting that Crenarchaeota may play a role in the oceanic nitrogen cycle. We enriched a crenarchaeote from North Sea water and showed that its abundance, and not that of bacteria, correlates with ammonium oxidation...

  8. The effect of temperature on the efficiency of industrial wastewater nitrification and its (geno)toxicity

    OpenAIRE

    Gnida Anna; Wiszniowski Jarosław; Felis Ewa; Sikora Jan; Surmacz-Górska Joanna; Miksch Korneliusz

    2016-01-01

    The paper deals with the problem of the determination of the effects of temperature on the efficiency of the nitrification process of industrial wastewater, as well as its toxicity to the test organisms. The study on nitrification efficiency was performed using wastewater from one of Polish chemical factories. The chemical factory produces nitrogen fertilizers and various chemicals. The investigated wastewater was taken from the influent to the industrial mechanical-biological wastewater trea...

  9. Development of a Biochar-Plant-Extract-Based Nitrification Inhibitor and Its Application in Field Conditions

    OpenAIRE

    Jhónatan Reyes-Escobar; Erick Zagal; Marco Sandoval; Rodrigo Navia; Cristina Muñoz

    2015-01-01

    The global use of nitrogen (N) fertilizer has increased 10-fold in the last fifty years, resulting in increased N losses via nitrate leaching to groundwater bodies or from gaseous emissions to the atmosphere. One of the biggest problems farmers face in agricultural production systems is the loss of N. In this context, novel biological nitrification inhibitors (BNI) using biochar (BC) as a renewable matrix to increase N use efficiency, by reducing nitrification rates, have been evaluated. The...

  10. The significance of water column nitrification in the southeastern Bering Sea

    Institute of Scientific and Technical Information of China (English)

    Clara J Deal; JIN Mei-bing; WANG Jia

    2008-01-01

    Nitrate is considered the nutrient that limits new primary production in the southeastern Bering Sea shelf. Nitrate regenerated through biological nitrification has the potential to significantly support primary production as well. Here we use measurements of the specific rate of water column nitrification in a 1-D ecosystem model to quantify the resupply of nitrate from nitrification in the middle shelf of the southeastern Bering Sea. Model sensitivity studies reveal nitrification rate is an important control on the dominant phytoplankton functional type, and the amount of nitrate in summer bottom waters and in the winter water column. Evaluation of nitrification using the model supports the hypothesis that increases in late-summer nitrate concentrations observed in the southeastern Bering Sea bottom waters are due to nitrification. Model results for nitrate replenishment exceed previously estimated rates of 20-30% based on observations. The results of this study indicate that nitrification, potentially the source of up to ~ 38% of the springtime water column nitrate, could support ~ 24% of the annual primary production.

  11. Nitrous oxide concentration and nitrification and denitrification in Zhujiang River Estuary, China

    Institute of Scientific and Technical Information of China (English)

    XU Jirong; WANG Youshao; WANG Qinji; YIN Jianping

    2005-01-01

    The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%~4 134% in the Zhujiang River Estuary.This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates ofnitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification,tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammonium concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.

  12. Effect of Gas/Water Ratio on the Performance of Combined Cylindrical Anoxic/Aerobic Moving Bed Biofilm Reactors for Biological Nutrients Removal from Domestic Wastewater by Fully Nitrification-Denitrification Processes

    OpenAIRE

    Husham T. Ibrahim; HEQiang; Wisaam S. Al-Rekabi

    2014-01-01

    In this research the continuously up-flow pilot scale Moving Bed Biofilm Reactor (MBBR) which was consists of combined cylindrical anoxic/aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 under fully nitrification-denitrification process were used to treated 4 m34+-N, TN and TP, respectively, while the average Dissolved Oxygen concentration (DO) in aerobic and anoxic MBBRs were 4.49 and 0.16 mg/L, respectively.

  13. Nitrification in Dutch heathland soils.

    OpenAIRE

    Boer, de, J.W.

    1989-01-01

    This thesis is the result of a study on the production of nitrate in Dutch heathland soils. Most of the heathlands are located on acid, sandy soils. Therefore , it has dealt mainly with the occurrence, nature and mechanisms of nitrification in acid soils. In the Netherlands, the production of nitrate in acid soils is a matter of great concern because it has become obvious that this process contributes to a continuous acidification of such soils that are exposed to high levels of deposition of...

  14. A comparison of two nitrification inhibitors used to measure nitrification rates in estuarine sediments

    Science.gov (United States)

    Caffrey, J.M.; Miller, L.G.

    1995-01-01

    Nitrification rates were measured using intact sediment cores from South San Francisco Bay and two different nitrification inhibitors: acetylene and methyl fluoride. Sediment oxygen consumption and ammonium and nitrate fluxes were also measured in these cores. Four experiments were conducted in the spring, and one in the fall of 1993. There was no significant difference in nitrification rates measured using the two inhibitors, which suggests that methyl fluoride can be used as an effective inhibitor of nitrification. Nitrification was positively correlated with sediment oxygen consumption and numbers of macrofauna. This suggests that bioturbation by macrofauna is an important control of nitrification rates. Irrigation by the tube-dwelling polychaete, Asychis elongata, which dominates the benthic biomass at this location, appears particularly important. Ammonium fluxes out of the sediment were greatest about one week after the spring bloom, while nitrification peaked about one month later.

  15. Nitrification in a zeoponic substrate

    Science.gov (United States)

    McGilloway, R. L.; Weaver, R. W.; Ming, D. W.; Gruener, J. E.

    2003-01-01

    Clinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.

  16. Efficiency of Heterotrophic Nitrification Bacteria in Biologically Enhanced Activated Carbon Process for Treatment of Low Temperature Water%异养硝化菌生物增强活性炭处理低温水的效能

    Institute of Scientific and Technical Information of China (English)

    秦雯; 李伟光; 张多英; 黄晓飞

    2013-01-01

    Biologically enhanced activated carbon (BEAC) filter columns were constructed to research the efficiency of heterotrophic nitrification bacteria Y7 and Y16 for treating low temperature water.The filter columns A,B and C were inoculated with Y7 strains,Y16 strains and Y7 + Y16 mixed bacteria,respectively,the filter column D was not inoculated as a control.The removal of NH4+-N and CODMn,the accumulation of NO2--N and NO3--N and the influence of different dissolved oxygen (DO) concentrations and filter speeds on the BEAC process were investigated at temperature of 5 ℃.The results showed that BEAC process was better than GAC process in NH4+-N removal,and the filter column C had the best removal efficiency of NH4+-N.The accumulation of NO2--N and NO3--N did not occur,and the maximum removal rates of NH4+-N and CODMn in the filter column C were 26.88% and 85.12%,respectively.Influent DO concentration had little impact on NH4+-N and CODMn removal in each filter column.Low filter speed was favorable for degradation of NH4+-N by BEAC,but not for removal of CODMn.%为研究异养硝化菌Y7和Y16对低温水的处理效果,构建生物增强活性炭(BEAC)滤柱,其中A滤柱接种Y7菌株,B滤柱接种Y16菌株,C滤柱接种Y7+ Y16混菌,以不接菌活性炭滤柱(D)作为对照.在5℃下研究了工艺对氨氮和CODMn的去除效果、亚硝酸盐氮与硝酸盐氮的积累特征以及进水DO含量和滤速对BEAC工艺运行效果的影响.结果表明,BEAC工艺对氨氮的去除效果优于GAC,其中C滤柱对氨氮的降解能力最强,运行期间并未出现硝酸盐氮与亚硝酸盐氮积累现象,启动期间对氨氮的最大去除率达到26.88%,对CODMn的最大去除率达到85.12%.进水溶解氧浓度对各滤柱去除氨氮和CODMn几乎没有影响;低滤速有利于BEAC对氨氮的降解,但对去除CODMn的影响较小.

  17. Effect of dissolved organic carbon quality on microbial decomposition and nitrification rates in stream sediments

    Science.gov (United States)

    Strauss, E.A.; Lamberti, G.A.

    2002-01-01

    1. Microbial decomposition of dissolved organic carbon (DOC) contributes to overall stream metabolism and can influence many processes in the nitrogen cycle, including nitrification. Little is known, however, about the relative decomposition rates of different DOC sources and their subsequent effect on nitrification. 2. In this study, labile fraction and overall microbial decomposition of DOC were measured for leaf leachates from 18 temperate forest tree species. Between 61 and 82% (mean, 75%) of the DOC was metabolized in 24 days. Significant differences among leachates were found for labile fraction rates (P carbon. 4. Nitrification rates in sediments also were measured after additions of four leachates and glucose at three carbon concentrations (10, 30, and 50 mg C L-1). For all carbon sources, nitrification rates decreased as carbon concentration increased. Glucose and white pine leachate most strongly depressed nitrification. Glucose likely increased the metabolism of heterotrophic bacteria, which then out-competed nitrifying bacteria for NH4+. White pine leachate probably increased heterotrophic metabolism and directly inhibited nitrification by allelopathy.

  18. Effect of organic loading on nitrification and denitrification in a marine sediment microcosm

    Science.gov (United States)

    Caffrey, J.M.; Sloth, N.P.; Kaspar, H.F.; Blackburn, T.H.

    1993-01-01

    The effects of organic additions on nitrification and denitrification were examined in sediment microcosms. The organic material, heat killed yeast, had a C/N ratio of 7.5 and was added to sieved, homogenized sediments. Four treatments were compared: no addition (control, 30 g dry weight (dw) m-2 mixed throughout the 10 cm sediment column (30 M), 100 g dw m-2 mixed throughout sediments (100M), and 100 g dw m-2 mixed into top 1 cm (100S). After the microcosms had been established for 7-11 days, depth of O2 penetration, sediment-water fluxes and nitrification rates were measured. Nitrification rates were measured using three different techniques: N-serve and acetylene inhibition in intact cores, and nitrification potentials in slurries. Increased organic additions decreased O2 penetration from 2.7 to 0.2 mm while increasing both O2 consumption, from 30 to 70 mmol O2 m-2 d-1, and NO3- flux into sediments. Nitrification rates in intact cores were similar for the two methods. Highest rates occurred in the 30 M treatment, while the lowest rate was measured in the 100S treatment. Total denitrification rates (estimated from nitrification and nitrate fluxes) increased with increased organic addition, because of the high concentrations of NO3- (40 ??M) in the overlying water. The ratio of nitrification: denitrification was used as an indication of the importance of nitrification as the NO3- supply for denitrification. This ratio decreased from 1.55 to 0.05 with increased organic addition.

  19. Effect of Gas/Water Ratio on the Performance of Combined Cylindrical Anoxic/Aerobic Moving Bed Biofilm Reactors for Biological Nutrients Removal from Domestic Wastewater by Fully Nitrification-Denitrification Processes

    Directory of Open Access Journals (Sweden)

    Husham T. Ibrahim

    2014-04-01

    Full Text Available In this research the continuously up-flow pilot scale Moving Bed Biofilm Reactor (MBBR which was consists of combined cylindrical anoxic/aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 under fully nitrification-denitrification process were used to treated 4 m34+-N, TN and TP, respectively, while the average Dissolved Oxygen concentration (DO in aerobic and anoxic MBBRs were 4.49 and 0.16 mg/L, respectively.

  20. Effects of urea and (NH4)2SO4 on nitrification and acidification of Ultisols from Southern China

    Institute of Scientific and Technical Information of China (English)

    Deli Tong; Renkou Xu

    2012-01-01

    The mechanisms for the effects of ammonium-based fertilizers on soil acidification in subtropical regions are not well understood.Two Ultisols collected from cropland and a tea garden in Anhui and Jiangxi Provinces in subtropical southern China,respectively,were used to study the effects of urea and (NH4)2SO4 on the nitrification and acidification of soils with incubation experiments.Nitrification occurred at very low pH with no N fertilizer added and led to lowering of the soil pH by 0.53 and 0.30 units for the soils from Jiangxi and Anhui,respectively.Addition of urea accelerated nitrification and soil acidification in both Ultisols; while nitrification was inhibited by the addition of (NH4)2SO4,and greater input of (NH4)2SO4 led to greater inhibition of nitrification.Ammonia-oxidizing bacteria (AOB) played an important role in nitrification in cropland soil under acidic conditions.Addition of urea increased the soil pH at the early stages of incubation due to hydrolysis and stimulated the increase in the AOB population,and thus accelerated nitrification and soil acidification.At the end of incubation,the pH of Ultisol from Jiangxi had decreased by 1.25,1.54 and 1.84 units compared to maximum values for the treatments with 150,300 and 400 mg/kg of urea-N added,respectively; the corresponding figures were 0.95,1.25 and 1.69 for the Ultisol from Anhui.However,addition of (NH4)2SO4 inhibited the increase in the AOB population and thus inhibited nitrification and soil acidification.Soil pH for the treatments with 300 and 400 mg/kg of (NH4)2SO4-N remained almost constant during the incubation.AOB played an important role in nitrification of the cropland soil under acidic conditions.Addition of urea stimulated the increase in the AOB population and thus accelerated nitrification and soil acidification; while addition of (NH4)2SO4inhibited the increase in the AOB population and thus inhibited nitrification.

  1. Osmotic stress on nitrification in an airlift bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin Rencun [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Zheng Ping [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Mahmood, Qaisar [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Hu Baolan [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)]. E-mail: blhu@zju.edu.cn

    2007-07-19

    The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L{sup -1} and hydraulic retention time at 20.7 h, with gradual increase in osmotic pressure from 4.3 to 18.8 x 10{sup 5} Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2 x 10{sup 5} Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2 x 10{sup 5} Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization.

  2. Osmotic stress on nitrification in an airlift bioreactor

    International Nuclear Information System (INIS)

    The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L-1 and hydraulic retention time at 20.7 h, with gradual increase in osmotic pressure from 4.3 to 18.8 x 105 Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2 x 105 Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2 x 105 Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization

  3. Seasonal Variation in Rates of Nitrification associated With Patterns of Carbon and Nitrogen Supply in a Southern Appalachian Headwater Stream

    OpenAIRE

    Starry, Olyssa Suzanne

    2004-01-01

    Abstract. Nitrification, the chemoautotrophic process via which ammonium-nitrogen (NH4-N) is converted to nitrate-nitrogen (NO3-N), is an important nitrogen (N) transformation in stream ecosystems. Experimental addition of dissolved organic carbon (DOC) has been shown to inhibit rates of nitrification, and rates have been stimulated by NH4-N addition. Insights regarding the role of particulate organic matter (POM) in this scenario could further enhance our understanding of linkages between...

  4. Regulation of the genes involved in nitrification.

    Energy Technology Data Exchange (ETDEWEB)

    Arp, D.J.; Sayavedra-Soto, L.A.

    2003-08-14

    OAK-B135 This project focuses on the characterization of the regulation of the genes involved in nitrification in the bacterium Nitrosomonas europaea. The key genes in the nitrification pathway, amo and hao, are present in multiple copies in the genome. The promoters for these genes were identified and characterized. It was shown that there were some differences in the transcriptional regulation of the copies of these genes.

  5. Protective effect of immobilized ammonia oxidizers and phenol-degrading bacteria on nitrification in ammonia- and phenol-containing wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Morita, M.; Watanabe, A. [Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Chiba (Japan); Kudo, N.; Shinozaki, H. [Materials Science Engineering, Tokyo Denki University, Tokyo (Japan); Uemoto, H.

    2007-12-15

    Phenol present in wastewaters from various industries has an inhibitory effect on nitrification even at low concentrations. Hence, the biological treatment of wastewater containing both phenol and ammonia involves a series of treatment steps. It is difficult to achieve nitrification capability in an activated sludge system that contains phenol at concentrations above the inhibitory level. Batch treatment of wastewater containing various concentrations of phenol showed that the ammonia oxidation capability of suspended Nitrosomonas europaea cells, an ammonia oxidizer, was completely inhibited in the presence of more than 5.0 mg/L phenol. To protect the ammonia oxidizer from the inhibitory effect of phenol and to achieve ammonia oxidation capability in the wastewater containing phenol at concentrations above the inhibitory level, a simple bacterial consortium composed of an ammonia oxidizer (N. europaea) and a phenol-degrading bacterial strain (Acinetobacter sp.) was used. Ammonia oxidation did not occur in the presence of phenol at concentrations above the inhibitory level when suspended or immobilized N. europaea and Acinetobacter sp. cells were used in batch treatment. Following the acclimatization of the immobilized cells, accumulation of nitrite was observed, even when the wastewater contained phenol at concentrations above the inhibitory level. These results showed that immobilization was effective in protecting N. europaea cells from the inhibitory effect of phenol present in the wastewater. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  6. The Biological Behaviors of Rat Dermal Fibroblasts Can Be Inhibited by High Levels of MMP9

    Directory of Open Access Journals (Sweden)

    Sheng-Neng Xue

    2012-01-01

    Full Text Available Aims. To explore the effects of the high expression of MMP9 on biological behaviors of fibroblasts. Methods. High glucose and hyperhomocysteine were used to induce MMP9 expression in skin fibroblasts. Cell proliferation was detected by flow cytometry and cell viability by CCK-8. ELISA assay was used to detect collagen (hydroxyproline secretion. Scratch test was employed to evaluate horizontal migration of cells and transwell method to evaluate vertical migration of cells. Results. The mRNA and protein expressions of MMP9 and its protease activity were significantly higher in cells treated with high glucose and hyperhomocysteine than those in control group. At the same time, the S-phase cell ratio, proliferation index, cell viability, collagen (hydroxyproline secretion, horizontal migration rate, and the number of vertical migration cells decreased in high-glucose and hyperhomocysteine-treated group. Tissue inhibitor of metalloproteinase 1 (TIMP1, which inhibits the activity of MMP9, recovered the above biological behaviors. Conclusions. High expression of MMP9 in skin fibroblasts could be induced by cultureing in high glucose and hyperhomocysteine medium, which inhibited cell biological behaviors. Inhibitions could be reversed by TIMP1. The findings suggested that MMP9 deters the healing of diabetic foot ulcers by inhibiting the biological behaviors of fibroblasts.

  7. Nitrification Potential of Mud Sediment of the Ariake Sea Tidal Flat and the Individual Effect of Temperature, pH, Salinity and Ammonium Concentration on its Nitrification Rate

    Directory of Open Access Journals (Sweden)

    Alim Isnansetyo

    2011-08-01

    Full Text Available The aims of this study were to know the nitrification potential of the mud sediment of the Ariake sea tidal flat, and to investigate the individual influence of environmental parameters such as temperature, pH, salinity and ammonium concentration on its nitrification rate. The Ariake Sea is a semi-closed shallow sea with macro-tidal and the largest tidal flat in Japan. Nitrification Potential Rate (NPR and Nitrification Rate (NR of the tidal flat mud sediment were determined by amending sodium chlorate to inhibit the oxidation of NO2-N to NO3-N. NPRs of the sediment were 91.4, 71.2 and 64.8 nmol N/g Dry Weight Sediment (DWS/h at the depth of 0-3, 3-6 and 6-9 cm, respectively. NRs were relatively high in the temperatures range of 20-35oC with the optimum temperature of 29.3oC. Relatively high NRs were determined in the range of pHs 7.5-8 with the optimum pH 7.7. The optimum salinity for nitrification was 15 ppt. NRs increased drastically in the range of salinity 10 to 15 ppt, but it decreased sharply at 15 to 20 ppt. Relationship between ammonium concentration and NR resulted a hyperbolic Michaëlis-Menten type curve (R2 = 0.98 with the maximum NR rate (Vmax 32.5 nmol N/g DWS/h at NH4-N concentration 3,000 mM and the half saturation constant (Ks 700 mM NH4-N. To our knowledge, this is the first report on nitrification of mud sediment of the Ariake sea tidal flat, and its optimal temperature, pH, salinity and NH4-N concentration as a single parameter.

  8. Neem seed oil: a potent nitrification inhibitor to control nitrate leaching after incorporation of crop residues

    OpenAIRE

    Opoku, A; Chaves, B; De Neve, Stefaan

    2014-01-01

    The effect of neem seed oil and neem leaf extract as organic nitrification inhibitors (NIs) on the accumulation of NH4+ and NO3-, and nitrification inhibition after incorporation of crop residue was investigated in an incubation experiment. Dicyandiamide (DCD) applications of 15 and 30 kg active ingredient ha(-1) were used as low and high doses of a synthetic NI. Soil samples were amended with 21 g kg(-1) cauliflower leaves and treated with NIs at a rate of 30 kg ha(-1) of neem seed oil, 60 k...

  9. Nitrification and denitrification in subalpine coniferous forests of different restoration stages in western Sichuan,China

    Institute of Scientific and Technical Information of China (English)

    LIU Yi; CHEN Jinsong; LIU Qing; WU Yan

    2007-01-01

    Nitrification is the biological conversion of organic or inorganic nitrogen compounds from a reduced to a more oxidized state.Denitrification is generally referred to as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide,nitrous oxide and molecular nitrogen.They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of longterm nitrogen losses in ecosystems through nitrate leaching and gaseous N losses.In" order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors,gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages.The results showed that forest restoration stage had no significant effects on gross nitrification rates or denitrification rates (One-way ANOVA (analysis of variance),p < 0.05).There was no significant difference in the temperature coefficient (Q10) for gross nitrification rate among all the forest sites (One-wayANOVA,p < 0.05).Gross nitrification rates were positively correlated with water content (p <0.05),but not with soil pH,organic matter,total nitrogen,or C/N ratios.Denitrification rates in all the forest soils were low and not closely correlated with water content,soil pH,organic matter,or total nitrogen.Nevertheless,we found that C/N ratios obviously affected denitrification rates (p < 0.05).Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils compared with denitrification.

  10. [Quick Start-up and Sustaining of Shortcut Nitrification in Continuous Flow Reactor].

    Science.gov (United States)

    Wu, Peng; Zhang Shi-ying; Song, Yin-ling; Xu, Yue-zhong; Shen, Yao-liang

    2016-04-15

    How to achieve fast and stable startup of shortcut nitrification has a very important practical value for treatment of low C/N ratio wastewater. Thus, the quick start-up and sustaining of shortcut nitrification were investigated in continuous flow reactor targeting at the current situation of urban wastewater treatment plant using a continuous flow process. The results showed that quick start-up of shortcut nitrification could be successfully achieved in a continuous flow reactor after 60 days' operation with intermittent aeration and controlling of three stages of stop/aeration time (15 min/45 min, 45 min/45 min and 30 min/30 min). The nitrification rates could reach 90% or 95% respectively, while influent ammonia concentrations were 50 or 100 mg · L⁻¹ with stop/aeration time of 30 min/30 min. In addition, intermittent aeration could inhibit the activity of nitrite oxidizing bacteria (NOB), while short hydraulic retention time (HRT) may wash out NOB. And a combined use of both measures was beneficial to sustain shortcut nitrification. PMID:27548971

  11. Effects of chlorothalonil and carbendazim on nitrification and denitrification in soils

    Institute of Scientific and Technical Information of China (English)

    LANG Man; CAI Zucong

    2009-01-01

    The effects of chlorothalonil and carbendazim, on nitrification and denitrification in six soils in upland and rice paddy environments were investigated. Laboratory aerobic (60% water holding capacity) and anaerobic (flooded) conditions were studied at an incubation temperature of 25℃ and fungicide addition rates of 5.5 mg/kg A. I. (field rate, FR), 20 (20FR) and 40 times (40FR) field rate, respectively. The results indicated that chlorothalonil at the field rate had a slight inhibitory effect on one soil only, and that soil did not nitrify much in the first place. But chlorothalonil at higher rates inhibited nitrification significantly in all soils. For soils JXP and JXU with a pH of less than 5.0, chlorothalonil almost completely stopped their nitrification at 20FR and 40FR during the whole 14 day incubation period. For soils HNP and HNU with a pH of greater than 8.0, chlorothalonil also significantly inhibit nitrification at 20FR and 40FR (p < 0.05). However, NH4+ that was added to the soil was also almost completely nitrified by the end of the incubation period in these two soils. The effects of chlorothalonil at 20FR and 40FR on the nitrification of JSP and JSU soils, with a pH of 5.4 and 7.2, respectively, were intermediate between the other soil types. Chlorothalonil had no effect on denitrification at the field rate and had very small effects at the higher rates of application in some soils. Carbendazim had essentially no effect on nitrification and denitrification in soils assessed.

  12. Heterogeneous Nitrification in a Full Scale Rapid Sand Filter Treating Groundwater

    DEFF Research Database (Denmark)

    Lopato, Laure; Röttgers, Nina; Binning, Philip John;

    2013-01-01

    and in space, vertically and laterally within the filter. The nitrification rate constants were calculated using the ammonium profiles and the local pore velocity data obtained from the breakthrough curves. The local pore velocities were estimated to vary from 0.02 to 20.5 m/h. The nitrification rate...... constants varied randomly in time and it was not possible to determine a clear order of the nitrification reaction. The average zero order nitrification rate constant was 7 mg N/l/h and the average first order nitrification rate constant was 28 h−1 with an average 1.5 g/h/m2 ammonium load. The first order......Experiments were conducted to determine ammonium removal kinetics in an operating biologically active sand filter at a waterworks treating anaerobic groundwater. The ammonium load varied between 0.7 and 3 g N/h/m2 (concentration ranged from 0.23 to 0.78 mg N/l) and the inlet water flux varied...

  13. Substrates and pathway of electricity generation in a nitrification-based microbial fuel cell.

    Science.gov (United States)

    Chen, Hui; Zheng, Ping; Zhang, Jiqiang; Xie, Zuofu; Ji, Junyuan; Ghulam, Abbas

    2014-06-01

    Nitrification-based microbial fuel cell (N-MFC) is a novel inorganic microbial fuel cell based on nitrification in the anode compartment. So far, little information is available on the substrates and pathway of N-MFC. The results of this study indicated that apart from the primary nitrification substrate (ammonium), the intermediates (hydroxylamine and nitrite) could also serve as anodic fuel to generate current, and the end product nitrate showed an inhibitory effect on electricity generation. Based on the research, a pathway of electricity generation was proposed for N-MFC: ammonium was oxidized first to nitrite by ammonia-oxidizing bacteria (AOB), then the nitrite in anolyte and the potassium permanganate in catholyte constituted a chemical cell to generate current. In other words, the electricity generation in N-MFC was not only supported by microbial reaction as we expected, but both biological and electrochemical reactions contributed. PMID:24704886

  14. Inhibition of survivin influences the biological activities of canine histiocytic sarcoma cell lines.

    Directory of Open Access Journals (Sweden)

    Hiroki Yamazaki

    Full Text Available Canine histiocytic sarcoma (CHS is an aggressive malignant neoplasm that originates from histiocytic lineage cells, including dendritic cells and macrophages, and is characterized by progressive local infiltration and a very high metastatic potential. Survivin is as an apoptotic inhibitory factor that has major functions in cell proliferation, including inhibition of apoptosis and regulation of cell division, and is expressed in most types of human and canine malignant neoplasms, including melanoma and osteosarcoma. To investigate whether survivin was expressed at high levels in CHS and whether its expression was correlated with the aggressive biological behavior of CHS, we assessed relation between survivin expression and CHS progression, as well as the effects of survivin inhibition on the biological activities of CHS cells. We comparatively analyzed the expression of 6 selected anti-apoptotic genes, including survivin, in specimens from 30 dogs with histiocytic sarcoma and performed annexin V staining to evaluate apoptosis, methylthiazole tetrazolium assays to assess cell viability and chemosensitivity, and latex bead assays to measure changes in phagocytic activities in 4 CHS cell lines and normal canine fibroblasts transfected with survivin siRNA. Survivin gene expression levels in 30 specimens were significantly higher than those of the other 6 genes. After transfection with survivin siRNA, apoptosis, cell growth inhibition, enhanced chemosensitivity, and weakened phagocytic activities were observed in all CHS cell lines. In contrast, normal canine fibroblasts were not significantly affected by survivin knockdown. These results suggested that survivin expression may mediate the aggressive biological activities of CHS and that survivin may be an effective therapeutic target for the treatment of CHS.

  15. Model predictive control of two-step nitrification and its validation via short-cut nitrification tests.

    Science.gov (United States)

    Sui, Jun; Luo, Fan; Li, Jie

    2016-10-01

    Short-cut nitrification (SCN) is shown to be an attractive technology due to its savings in aeration and external carbon source addition cost. However, the shortage of excluding nitrite nitrogen as a model state in an Activated Sludge Model limits the model predictive control of biological nitrogen removal via SCN. In this paper, a two-step kinetic model was developed based on the introduction of pH and temperature as process controller, and it was implemented in an SBR reactor. The simulation results for optimizing operating conditions showed that with increasing of dissolved oxygen (DO) the rate of ammonia oxidation and nitrite accumulation firstly increased in order to achieve a SCN process. By further increasing DO, the SCN process can be transformed into a complete nitrification process. In addition, within a certain range, increasing sludge retention time and aeration time are beneficial to the accumulation of nitrite. The implementation results in the SBR reactor showed that the data predicted by the kinetic model are in agreement with the data obtained, which indicate that the two-step kinetic model is appropriate to simulate the ammonia removal and nitrite production kinetics. PMID:26901147

  16. Temperature effect on aerobic denitrification and nitrification

    Institute of Scientific and Technical Information of China (English)

    XIE Shu-guang; ZHANG Xiao-jian; WANG Zhan-sheng

    2003-01-01

    Nitrogen loss without organic removal in biofilter was observed and its possible reason was explained. A lower hydraulic loading could improve aerobic denitrification rate. Aerobic denitrification was seriously affected by low temperature(below 10oC). However, nitrification rate remained high when the temperature dropped from 15oC to5oC. It seemed the autotrophic biofilm in BAF could alleviate the adverse effect of low temperature.

  17. Nitrification of Landfill Leachate by Biofilm Columns

    OpenAIRE

    Clabaugh, Matthew McConnell

    2001-01-01

    NITRIFICATION OF LANDFILL LEACHATE BY BIOFILM COLUMNS by Matthew M. Clabaugh J.T. Novak, Chairman Department of Environmental Engineering (ABSTRACT) Landfill leachate characteristics vary depending on the operation type of the landfill and the age of the landfill. At landfills operated as bioreactors, where leachate recirculation is practiced, leachate ammonia nitrogen concentrations may accumulate to extremely higher levels than during single pass leaching, thereby requi...

  18. Effect of heavy metals on nitrification activity as measured by RNA- and DNA-based function-specific assays

    Science.gov (United States)

    Heavy metals can inhibit nitrification, a key process for nitrogen removal in wastewater treatment. The transcriptional responses of functional genes (amoA, hao, nirK and norB) were measured in conjunction with specific oxygen uptake rate (sOUR) for nitrifying enrichment cultures...

  19. [Effect of osmotic pressure on nitrification].

    Science.gov (United States)

    Zheng, Ping; Wu, Ming-Sheng

    2006-01-01

    The effect of osmotic pressure on nitrification was investigated in the internal-loop air-lift nitrifying reactor. When influent ammonia concentration is kept at 420mg x L(-1) and influent osmotic pressure is increased from 4.3 to 18.8 x 10(5) Pa, the ammonia conversion of the nitrifying bioreactor is maintained between 93% and 100%. After influent osmotic pressure is further increased to 19.2 x 10(5)Pa, the ammonia conversion goes down to 69.2%. The influence of osmotic pressure on nitrification takes place without any alarm and the critical osmotic pressure is between 18.8 x 10(5) and 19.2 x 10(5) Pa. During osmotic stress, the nitrifying bacterial populations in the activated sludge become simplified, the cell size becomes smaller, the inner membrane becomes less and some unknown inclusion particles are formed. The cell structure is restored as soon as the osmotic pressure is removed. Addition of potassium is able to relieve the effect of osmotic pressure on nitrification. The nitrifying activity of the activated sludge is stimulated by the osmotic stress, and the specific ammonia conversion is increased from 0.083 kg x kg(-1) x d(-1) to 0.509 kg x kg(-1) x d(-1) and 2.569 kg x kg(-1) x d(-1), respectively. PMID:16572857

  20. Use of functional gene expression and respirometry to study wastewater nitrification activity after exposure to low doses of copper.

    Science.gov (United States)

    Kapoor, Vikram; Li, Xuan; Chandran, Kartik; Impellitteri, Christopher A; Santo Domingo, Jorge W

    2016-04-01

    Autotrophic nitrification in biological nitrogen removal systems has been shown to be sensitive to the presence of heavy metals in wastewater treatment plants. Using transcriptase-quantitative polymerase chain reaction (RT-qPCR) data, we examined the effect of copper on the relative expression of functional genes (i.e., amoA, hao, nirK, and norB) involved in redox nitrogen transformation in batch enrichment cultures obtained from a nitrifying bioreactor operated as a continuous reactor (24-h hydraulic retention time). 16S ribosomal RNA (rRNA) gene next-generation sequencing showed that Nitrosomonas-like populations represented 60-70% of the bacterial community, while other nitrifiers represented amoA and hao and ammonia removal in the bioreactor. There were no considerable changes in the transcript levels of amoA, hao, nirK, and norB for nitrifying samples exposed to copper dosages ranging from 0.01 to 10 mg/L for a period of 12 h. Similar results were obtained when ammonia oxidation activity was measured via specific oxygen uptake rate (sOUR). The lack of nitrification inhibition by copper at doses lower than 10 mg/L may be attributed to the role of copper as cofactor for ammonia monooxygenase or to the sub-inhibitory concentrations of copper used in this study. Overall, these results demonstrate the use of molecular methods combined with conventional respirometry assays to better understand the response of wastewater nitrifying systems to the presence of copper. PMID:26627696

  1. Distribution variation of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP) in long-term sludge culture and their effects on sludge reduction and biological inhibition.

    Science.gov (United States)

    Tian, Yu; Zhang, Jun; Wu, Di; Li, Zhipeng; Cui, Yanni

    2013-01-01

    Distribution variation of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP), in long-term sludge culture was studied, and the effects on sludge reduction and biological inhibition of this chemical during the 90-day operation were established. The extracellular polymeric substance (EPS) matrix functioned as a protective barrier for the bacteria inside sludge flocs to 2,6-DCP, resulting in the transfer of 2,6-DCP from the liquid phase to the activated sludge fraction. Significant sludge reduction (about 40%) was observed after the addition of 2,6-DCP in the first 40 days, while the ineffective function of 2,6-DCP in sludge reduction (days 70-90) might be correlated to the EPS protection mechanism. The inhibitory effect of 2,6-DCP on the COD removal was extremely lower than on the nitrification performance due to the fact that 2,6-DCP was much more toxic to autotrophic microorganisms than heterotrophic microorganisms. Moreover, both of them recovered to a higher level again with the transfer potential of 2,6-DCP to sludge. Thus, the application of metabolic uncoupler for excess sludge reduction should be cautious. PMID:23123050

  2. Nitrification in thermally altered black-water streams

    International Nuclear Information System (INIS)

    For each stream at each concentration of nitrite, a linear regression over time was performed. The generated slope represents the rate of change in the amount of nitrite nirogen present per hour in the chambers. The absolute value of the slopes (rate of nitrification) were plotted against the mean absolute temperature of the stream for the period of the experiment. The maximum rate of nitrification occurred at a temperature of 50 or 7.50C above ambient. The maximum rate of nitrification occurred near 250C. The nitrifying population appeared to have the highest densities in the 5.00 and 7.50C above ambient streams. The data suggest that nitrification is enhanced by thermal alterations up to about 250C (ΔT of 7.50C); but above such levels, the rate of nitrification decreases. The density measurements of Nitrobacter futher support the observation that increased rates of nitrification are influenced by increases in temperature

  3. Online measurement of nitrification inhibitors in sewage received by an industrial sewage treatment plant. Development of a nitrification toximeter; Online-Messung nitrifikationshemmender Stoffe im Zulauf einer Industrieklaeranlage - Entwicklung eines Nitrifikationstoximeters

    Energy Technology Data Exchange (ETDEWEB)

    Haid, M. [BASF AG, Ludwigshafen am Rhein (Germany)

    1999-07-01

    At an industrial sewage treatment plant, the ammonium freight in the effluent is to be further reduced in the future through nitrification. But constantly low effluent concentrations are only possible if the nitrification process is not inhibited. Bouts of critical concentrations of nitrification inhibitors in sewage received by treatment plant are potentially disturbing. Online measurement of nitrification inhibitors in sewage arriving at the treatment plant is to recognize such bouts and permit timely alert so that counter-measures can be taken, which may consist in routing sewage with such toxic concentrations into a storage basin, whereby a sharp slump in the nitrification process can be avoided. (orig.) [German] In einer Industrieklaeranlage soll kuenftig durch Nitrifikation die Ammoniumfracht im Auslauf weiter gesenkt werden. Konstant niedrige Ablaufwerte sind aber nur dann moeglich, wenn der Nitrifikationsprozess ungestoert ablaufen kann. Stoesse nitrifikationshemmender Stoffe in kritischen Konzentrationen im Zulauf zur Klaeranlage sind eine moegliche Stoergroesse. Mit Hilfe einer Online-Nitrifikationshemmmessung im Klaeranlagenzulauf sollen solche Stoesse erkannt und rechtzeitig alarmiert werden, damit Gegenmassnahmen, wie z.B. das Auffangen des toxischen Stosses durch eine Sicherheitsschaltung in einem Speicherbecken, eingeleitet und so signifikante Einbrueche des Nitrifikationsprozesses vermieden werden koennen. (orig.)

  4. Toxicity of Nitrification Inhibitors on Dehydrogenase Activity in Soils

    Directory of Open Access Journals (Sweden)

    Ferisman Tindaon

    2011-01-01

    Full Text Available The objective of this research was to determine the effects of nitrification inhibitors (NIs such as 3,4-dimethylpyrazolephosphate=DMPP, 4-Chlor-methylpyrazole phosphate=ClMPP and dicyandiamide,DCD which might be expected to inhibit microbial activity, on dehydrogenase activity (DRA,in three different soils in laboratory conditions. Dehydrogenase activity were assessed via reduction of 2-p-Iodophenyl-3-p-nitrophenyl-5-phenyltetrazoliumchloride (INT. The toxicity and dose response curve of three NIs were quantified under laboratory conditions using a loamy clay, a sandy loam and a sandy soil. The quantitative determination of DHA was carried out spectrophotometrically. In all experiments, the influence of 5-1000 times the base concentration were examined. To evaluate the rate of inhibition with the increasing NI concentrations, dose reponse curves were presented and no observable effect level =NOEL, as well as effective dose ED10 and ED 50(10% and 50% inhibition were calculated. The NOEL for common microbial activity such as DHA was about 30–70 times higher than base concentration in all investigated soils. ClMPP exhibited the strongest influence on the non target microbial processes in the three soils if it compare to DMPP and DCD. The NOEL,ED10 and ED50 values higher in clay than in loamy or sandy soil. The NIs were generally most effective in sandy soils. The three NIs considered at the present state of knowledge as environmentally safe in use.

  5. NITROGEN LOSSES DUE TO NITRIFICATION: PLANT BASED REMEDIAL PROSPECTS

    OpenAIRE

    Kavita Arora and Alka Srivastava*

    2013-01-01

    Nitrification of nitrogen fertilizers results into loss of nitrogen nutrient from soil along with environmental hazards, like, global warming, contamination of ground water and so on. To tackle the problem, many synthetic inhibitors of nitrification have been formulated but till now none of them has proved to be attractive option due to their cost and non-ecofriendly nature. A shift towards natural nitrification inhibitors would be beneficial, economically viable and environmentally safer opt...

  6. [Effects of L-methionine on nitrification and N2O emission in subtropical forest soil].

    Science.gov (United States)

    Lin, Wei; Pei, Guang-ting; Ma, Hong-liang; Gao, Ren; Yin, Yun-feng; Peng, Yuan-zhen

    2015-09-01

    The objective of this study was to investigate the influence of L-methionine on nitrification and nitrous oxide emission in a red soil under laboratory incubation experiments. A subtropical broad-leaved forest soil sample was collected from Wanmulin natural reserve in Fujian Province, Southeast China. Five treatments were carried out with three replications, i. e., control (CK), L- methionine addition (M), L-methionine and NH(4+)-N addition (MA), L-methionine and NO(2-)-N addition (MN), L-methionine and glucose addition (MC). The soil moisture was maintained at 60% WHC or 90% WHC. The results indicated that the soil NH(4+)-N content in the M treatment significantly increased by 0.8%-61.3%, while the soil NO(3-)-N content reduced by 13.2%-40.7% compared with CK. Under 60% WHC condition, soil NO(2-)-N content in the MC treatment was higher than in the M treatment, soil NO(3-)-N content in the MA and MN treatments were greater than that in the M treatment, and greater in the MN treatment than in the MA treatment. The soil NO(3-)-N content was lowest in the M treatment after incubation. These results suggested that L-methionine could inhibit nitrosation process of autotrophic nitrification. To some extent, carbon addition as glucose with L-methionine decreased the NH(4+)-N content, inhibited the autotrophic nitrification and their effects were dependent on water level. Under 90% WHC condition, carbon addition improved denitrification more obviously, but the decrease of NO(3-)-N content was not sufficient to prove the inhibition of hetero-nitrification due to carbon addition in the presence of L-methionine. The nitrous oxide emission from soil was increased by L-methionine addition. Compared with 60% WHC condition, the nitrous oxide emission was higher under 90% WHC condition, and the promotion of L-methionine addition on N2O was greater when glucose added. PMID:26785545

  7. The herbicide Glyphosate affects nitrification in the Elbe estuary, Germany

    Science.gov (United States)

    Sanders, Tina; Lassen, Stephan

    2015-04-01

    The Elbe River is one of the biggest European rivers discharging into the North Sea. It also transports high amounts of nutrients and pollutants like pesticides. Important source regions of both nutrients and pollutants are located within the river catchment, which is dominated by agricultural land-use. From these agricultural soils, pesticides can be carried via the river and estuary into the North Sea. Glyphosate (N-(phosphonomethyl) glycine) is the most commonly used herbicide worldwide and mainly used to regulate unwanted plant growth and for the expedition of crop ripening. In Germany, ~ 6000 tons of glyphosate are applied yearly in agriculture and private use. Glyphosate is degradable by microorganisms and has a half-life in water of 35 to 60 days. This herbicide specifically inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), an enzyme that catalyzes the biosynthesis of essential aromatic amino acids in plants, fungi, and bacteria. Nitrifying bacteria, which play an important role in the internal nitrogen cycling in the Elbe estuary, also possess this enzyme. The aim of our study was to quantify the concentration of glyphosate in water and sediment samples of the Elbe to get an overview about relevant environmental levels and to assess the impact of glyphosate on inhibition of nitrifying activities. To quantify the effect of glyphosate on nitrification activity, natural samples as well as pure cultures of Nitrosomonas europea (strain Nm50) were incubated with different concentrations of glyphosate over a period of some weeks. The nitrifying activity was determined according to changes of the nitrite and nitrate concentration as well as the cell number. Glyphosate was detectable in water and sediment samples in the Elbe estuary with up to 5 ppb mainly in the Port of Hamburg region. In both incubation experiments an inhibiting effect of glyphosate on nitrification could be shown. The incubated natural water sample was affected by a glyphosate

  8. Coupling of nitrification and denitrification in two estuarine sediments

    International Nuclear Information System (INIS)

    Nitrification and denitrification in estuarine sediments were measured by 15N isotopic tracer techniques at two stations in the Patuxent River estuary for April and August. A close coupling of the two processes was demonstrated directly from the evolution of labeled N2 following 15NH4+ amendments during spring experiments. In contrast, this coupled nitrification-denitrification was decreased by two orders of magnitude in the summer, even though the capacity for denitrification remained similar to spring levels. This pattern of sharply seasonal nitrification was corroborated with measurements of bacterial relative abundance. Ambient rates of nitrification-denitrification were inferred from 15N experiments in these sediments

  9. Nitrification/denitrification - new aspects and treatment methods

    International Nuclear Information System (INIS)

    Different nitrification and denitrification treatment methods are discussed regarding the nitrogen cycle and its importance for wastewater treatment plants. A simultaneous denitrification process and a denitrification/nitrification multistage mode process were compared to a nitrification/denitrification multistage mode process. A nitrification/denitrification multistage process appears to be an efficient and economical alternative, if the EC-regulations of 21 May 1991 require a nitrogen-elimination > 70%. This process is especially well suited for wastewater with a low C/N ratio and for industrial wastewater (e.g. landfill leachate). (orig.)

  10. A systems biology framework for modeling metabolic enzyme inhibition of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Reifman Jaques

    2009-09-01

    Full Text Available Abstract Background Because metabolism is fundamental in sustaining microbial life, drugs that target pathogen-specific metabolic enzymes and pathways can be very effective. In particular, the metabolic challenges faced by intracellular pathogens, such as Mycobacterium tuberculosis, residing in the infected host provide novel opportunities for therapeutic intervention. Results We developed a mathematical framework to simulate the effects on the growth of a pathogen when enzymes in its metabolic pathways are inhibited. Combining detailed models of enzyme kinetics, a complete metabolic network description as modeled by flux balance analysis, and a dynamic cell population growth model, we quantitatively modeled and predicted the dose-response of the 3-nitropropionate inhibitor on the growth of M. tuberculosis in a medium whose carbon source was restricted to fatty acids, and that of the 5'-O-(N-salicylsulfamoyl adenosine inhibitor in a medium with low-iron concentration. Conclusion The predicted results quantitatively reproduced the experimentally measured dose-response curves, ranging over three orders of magnitude in inhibitor concentration. Thus, by allowing for detailed specifications of the underlying enzymatic kinetics, metabolic reactions/constraints, and growth media, our model captured the essential chemical and biological factors that determine the effects of drug inhibition on in vitro growth of M. tuberculosis cells.

  11. An efficient process for wastewater treatment to mitigate free nitrous acid generation and its inhibition on biological phosphorus removal

    OpenAIRE

    Zhao, Jianwei; Wang, Dongbo; Li, Xiaoming; Yang, Qi; Chen, Hongbo; Zhong, Yu; An, Hongxue; Zeng, Guangming

    2015-01-01

    Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher ph...

  12. Biological effects of ruthenium, osmium and copper complexes with tumour inhibiting ligands

    International Nuclear Information System (INIS)

    Many substances active against neoplastic cells lack solubility and bioavailability. Standard therapies using well-known platin analogues, among them cisplatin, can only cure a few types of malignances and have serious side effects. A major problem with many tumours is the occurrence of acquired and/or intrinsic resistance. In this study as an alternative to platinum agents, new complexes of ruthenium, osmium and copper complexes with pronouncedly biologically active ligands (indolobenzazepines, indolochinolines, chinoxalinones, flavones and benzimidazolyl-pyrazolo-pyridines) were under investigation in order to improve the desired destructive impact on cancer cells. Formulation complexes with transition metal centers which are binding to DNA or other biomolecules and biologically active ligands may yield synergistic effects, enhance the solubility of ligands and act against cancer cells in two ways. Modification of these complexes by changing the metal center and different ligands as well as an alteration of substituents were investigated in order to find a stable, well soluble and optimal structure for biomolecule interaction. The cell cycle regulated by cyclin-dependent kinases (Cdks) and their modulators is a major target of cancer therapy. Many ATP antagonists were synthesized, but among them there are only a few that have reached the stage of clinical trials. All complexes investigated here were tested as to their cytotoxic potency with three cancer cell lines (A549, CH1, SW480), some of them with three additional ones (LNCaP, T47D, N87) by an MTT assay. The results of structure-activity relationships of different cell lines were compared. All compounds under investigation showed cytotoxic potency with IC50 values in the micromolar to nanomolar range. Results with respect to selected compounds were then compared as to their influence on the cell cycle which was in most cases rather weak, and as to the induction of apoptosis (Annexin/PI stain), both measured

  13. Antisense oligodeoxynucleotide inhibition as a potent diagnostic tool for gene function in plant biology

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Christer; Sun, Chuanxin; Ghebramedhin, Haile; Hoglund, Anna-Stina; Jansson, Christer

    2008-01-15

    Antisense oligodeoxynucleotide (ODN) inhibition emerges as an effective means for probing gene function in plant cells. Employing this method we have established the importance of the SUSIBA2 transcription factor for regulation of starch synthesis in barley endosperm, and arrived at a model for the role of the SUSIBAs in sugar signaling and source-sink commutation during cereal endosperm development. In this addendum we provide additional data demonstrating the suitability of the antisense ODN technology in studies on starch branching enzyme activities in barley leaves. We also comment on the mechanism for ODN uptake in plant cells. Antisense ODNs are short (12-25 nt-long) stretches of single-stranded ODNs that hybridize to the cognate mRNA in a sequence-specific manner, thereby inhibiting gene expression. They are naturally occurring in both prokaryotes and eukaryotes where they partake in gene regulation and defense against viral infection. The mechanisms for antisense ODN inhibition are not fully understood but it is generally considered that the ODN either sterically interferes with translation or promotes transcript degradation by RNase H activation. The earliest indication of the usefulness of antisense ODN technology for the purposes of molecular biology and medical therapy was the demonstration in 1978 that synthetic ODNs complementary to Raos sarcoma virus could inhibit virus replication in tissue cultures of chick embryo fibroblasts. Since then the antisense ODN technology has been widely used in animal sciences and as an important emerging therapeutic approach in clinical medicine. However, antisense ODN inhibition has been an under-exploited strategy for plant tissues, although the prospects for plant cells in suspension cultures to take up single-stranded ODNs was reported over a decade ago. In 2001, two reports from Malho and coworker demonstrated the use of cationic-complexed antisense ODNs to suppress expression of genes encoding pollen

  14. Nitrification Processes in Tehran Wastewater Treatment Plant

    OpenAIRE

    S. A. Sadrnejad

    2011-01-01

    A wastewater treatment plant is designed to daily treat 450000 m3 of wastewater collected from the city of Tehran. The wastewater treatment plant is located at the south of Shahr-Ray in southern Tehran with the area of 110 hectares. The treatment plant effluent will be transferred to Varamin agricultural lands to be used for the irrigation of crops. A conventional activated sludge for carbon removal and a high-rate trickling filter for nitrification of ammonia to nitrate are designed and cons...

  15. Biodegradation of plastics in soil and effects on nitrification activity. A laboratory approach.

    Directory of Open Access Journals (Sweden)

    Giulia eBettas Ardisson

    2014-12-01

    Full Text Available The progressive application of new biodegradable plastics in agriculture calls for improved testing approaches to assure their environmental safety. Full biodegradation (≥ 90% prevents accumulation in soil, which is the first tier of testing. The application of specific ecotoxicity tests is the second tier of testing needed to show safety for the soil ecosystem. Soil microbial nitrification is widely used as a bioindicator for evaluating the impact of chemicals on soil but it is not applied for evaluating the impact of biodegradable plastics. In this work the International Standard test for biodegradation of plastics in soil (ISO 17556, 2012 was applied both to measure biodegradation and to prepare soil samples needed for a subsequent nitrification test based on another International Standard (ISO 14238, 2012. The plastic mulch film tested in this work showed full biodegradability and no inhibition of the nitrification potential of the soil in comparison with the controls. The laboratory approach suggested in this Technology Report enables (i to follow the course of biodegradation, (ii a strict control of variables and environmental conditions, (iii the application of very high concentrations of test material (to maximize the possible effects. This testing approach could be taken into consideration in improved testing schemes aimed at defining the biodegradability of plastics in soil.

  16. Factors regulating nitrification in aquatic sediments: Effects of organic carbon, nitrogen availability, and pH

    Science.gov (United States)

    Strauss, E.A.; Mitchell, N.L.; Lamberti, G.A.

    2002-01-01

    We investigated the response in nitrification to organic carbon (C) availability, the interactive effects of the C: nitrogen (N) ratio and organic N availability, and differing pH in sediments from several streams in the upper midwestern United States. In addition, we surveyed 36 streams to assess variability in sediment nitrification rates. Labile dissolved organic carbon (DOC) additions of 30 mg C??L-1 (as acetate) to stream sediments reduced nitrification rates (P nitrification. C:N and organic N availability strongly interacted to affect nitrification (P nitrification most at lower C:N. Nitrification was also strongly influenced by pH (P nitrification. Our results suggest that nitrification is regulated by several variables, with NH4+ availability and pH being the most important. Organic C is likely important at regulating nitrification only under high environmental C:N conditions and if most available C is relatively labile.

  17. Processes effecting nitrification performance in biological rapid sand filters

    DEFF Research Database (Denmark)

    Lee, Carson Odell; Boe-Hansen, Rasmus

    Grundvand, der anvendes i drikkevandsforsyningen, indeholder ammonium, der skal fjernes for at sikre en god drikkevandskvalitet. Nitrifikation i biologisk aktive hurtige sandfiltre er en stadig mere udbredt teknik til at fjerne vandets indhold af ammonium. På trods af den udbredte anvendelse af n...

  18. Simultaneous Nitrification and Denitrification in Aerobic Chemostat Cultures of Thiosphaera pantotropha

    OpenAIRE

    Robertson, L.A.; van Niel, E.W.; Torremans, R.A.; Kuenen, J. G.

    1988-01-01

    Thiosphaera pantotropha is capable of simultaneous heterotrophic nitrification and aerobic denitrification. Consequently, its nitrification potential could not be judged from nitrite accumulation, but was estimated from complete nitrogen balances. The maximum rate of nitrification obtained during these experiments was 93.9 nmol min−1 mg of protein−1. The nitrification rate could be reduced by the provision of nitrate, nitrite, or thiosulfate to the culture medium. Both nitrification and denit...

  19. Nitrification in the Schelde estuary: methodological aspects and factors influencing its activity

    OpenAIRE

    Bie, M.J.M. de; Starink, M.; Boschker, H.T.S.; Peene, J.J.; Laanbroek, H. J.

    2002-01-01

    We present a 15-month dataset on nitrification measurements in the Schelde estuary (Belgium and The Netherlands). Nitrification was estimated using the N-serve sensitive dark 14C-bicarbonate incorporation technique. A peak of nitrification activity was observed in the freshwater part of the estuary. Downstream from this peak, nitrification declined, probably because of ammonium limitation. A range of nitrification inhibitors was tested on both a Nitrosomonas europaea culture and estuarine sam...

  20. Nitrification and denitrification gene abundances in swine wastewater anaerobic lagoons

    Science.gov (United States)

    Although anaerobic lagoons are used globally for livestock waste treatment, their detailed microbial cycling of nitrogen is only beginning to become understood. Within this cycling, nitrification can be performed by organisms which produce the enzyme ammonia monooxygenase (AMO). For denitrification,...

  1. Nitrification at different salinities: Biofilm community composition and physiological plasticity.

    Science.gov (United States)

    Gonzalez-Silva, Blanca M; Jonassen, Kjell Rune; Bakke, Ingrid; Østgaard, Kjetill; Vadstein, Olav

    2016-05-15

    This paper describes an experimental study of microbial communities of three moving bed biofilm reactors (MBBR) inoculated with nitrifying cultures originated from environments with different salinity; freshwater, brackish (20‰) and seawater. All reactors were run until they operated at a conversion efficiency of >96%. The microbial communities were profiled using 454-pyrosequencing of 16S rRNA gene amplicons. Statistical analysis was used to investigate the differences in microbial community structure and distribution of the nitrifying populations with different salinity environments. Nonmetric multidimensional scaling analysis (NMDS) and the PERMANOVA test based on Bray-Curtis similarities revealed significantly different community structure in the three reactors. The brackish reactor showed lower diversity index than fresh and seawater reactors. Venn diagram showed that 60 and 78% of the total operational taxonomic units (OTUs) in the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) guild, respectively, were unique OTUs for a given reactor. Similarity Percentages (SIMPER) analysis showed that two-thirds of the total difference in community structure between the reactors was explained by 10 OTUs, indicating that only a small number of OTUs play a numerically dominant role in the nitrification process. Acute toxicity of salt stress on ammonium and nitrite oxidizing activities showed distinctly different patterns, reaching 97% inhibition of the freshwater reactor for ammonium oxidation rate. In the brackish culture, inhibition was only observed at maximal level of salinity, 32‰. In the fully adapted seawater culture, higher activities were observed at 32‰ than at any of the lower salinities. PMID:26986496

  2. Nitrification Potential of Soils Under Liquid Incubation Conditions

    Institute of Scientific and Technical Information of China (English)

    YUAN Fei; RAN Wei; SHEN Qi-Rong

    2005-01-01

    A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)2SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, the amounts of nitrifying bacteria in the three soils were not related to soil nitrification capacity. When the soil samples or the isolates of AOB enriched from the corresponding soil were incubated in liquid with pH 5.8, 7.0 and 8.0 buffers and 10 mmol L-1 ammonium nitrogen, there were no significant nitrification differences in the same soil type at each pH. The ability to oxidize ammonia through AOB from different types of soils in a homogeneous culture medium was similar, and the soil nitrification capacity could reflect the inherent properties of a soil. Altering the culture medium pH of individual soil type also showed that acidification of an alkaline fluvo-aquic soil decreased nitrification capacity, whereas alkalinization of the acidic red soil and permeable paddy soil increased their nitrification. For a better insight into factors influencing soil nitrification processes, soil properties including texture and clay composition should be considered.

  3. Nitrification Potential of Soils under Pollution of a Fertilizer Plant

    OpenAIRE

    Gintarė Sujetovienė

    2010-01-01

    Nitrogen compounds found in soil in the form of mineral and organic bonds are available to microbes and plants as NO3- and NH4+, produced in consequence of ammonification, nitrification and N fixation. The laboratory experiment was conducted on samples of podzolic sandy soils. Soil samples were taken in the surroundings of a nitrogen fertilizer plant Achema, situated in the center of Lithuania. The objective of the study was to determine the effect of soil contamination on the nitrification p...

  4. Stratification of nitrification activity in rapid sand filters for drinking water treatment

    DEFF Research Database (Denmark)

    Tatari, Karolina; Smets, Barth F.; Musovic, Sanin;

    2013-01-01

    layers. A water sampler was installed in the full scale filter of plant 1 to observe the ammonium profile with depth. Ammonium was removed within the upper 15 cm with a removal rate ranging of 3.6- 7.7 g NH4+-N/ m3 sand/h. Full scale observations fit with the lab scale activity measurements showing that......Rapid sand filters used in groundwater treatment remove ammonium, iron and manganese from the water. Ammonium is removed biologically by nitrifying microorganisms attached on the sand surface. Nitrification kinetics and activity is strongly affected by filter design and operation, which are the key...

  5. Mechanism of biological denitrification inhibition: procyanidins induce an allosteric transition of the membrane-bound nitrate reductase through membrane alteration.

    Science.gov (United States)

    Bardon, Clément; Poly, Franck; Piola, Florence; Pancton, Muriel; Comte, Gilles; Meiffren, Guillaume; Haichar, Feth El Zahar

    2016-05-01

    Recently, it has been shown that procyanidins fromFallopiaspp. inhibit bacterial denitrification, a phenomenon called biological denitrification inhibition (BDI). However, the mechanisms involved in such a process remain unknown. Here, we investigate the mechanisms of BDI involving procyanidins, using the model strainPseudomonas brassicacearumNFM 421. The aerobic and anaerobic (denitrification) respiration, cell permeability and cell viability ofP. brassicacearumwere determined as a function of procyanidin concentration. The effect of procyanidins on the bacterial membrane was observed using transmission electronic microscopy. Bacterial growth, denitrification, NO3- and NO2-reductase activity, and the expression of subunits of NO3- (encoded by the genenarG) and NO2-reductase (encoded by the genenirS) under NO3or NO2were measured with and without procyanidins. Procyanidins inhibited the denitrification process without affecting aerobic respiration at low concentrations. Procyanidins also disturbed cell membranes without affecting cell viability. They specifically inhibited NO3- but not NO2-reductase.Pseudomonas brassicacearumresponded to procyanidins by over-expression of the membrane-bound NO3-reductase subunit (encoded by the genenarG). Our results suggest that procyanidins can specifically inhibit membrane-bound NO3-reductase inducing enzymatic conformational changes through membrane disturbance and thatP. brassicacearumresponds by over-expressing membrane-bound NO3-reductase. Our results lead the way to a better understanding of BDI. PMID:26906096

  6. Complete nitrification by a single microorganism.

    Science.gov (United States)

    van Kessel, Maartje A H J; Speth, Daan R; Albertsen, Mads; Nielsen, Per H; Op den Camp, Huub J M; Kartal, Boran; Jetten, Mike S M; Lücker, Sebastian

    2015-12-24

    Nitrification is a two-step process where ammonia is first oxidized to nitrite by ammonia-oxidizing bacteria and/or archaea, and subsequently to nitrate by nitrite-oxidizing bacteria. Already described by Winogradsky in 1890, this division of labour between the two functional groups is a generally accepted characteristic of the biogeochemical nitrogen cycle. Complete oxidation of ammonia to nitrate in one organism (complete ammonia oxidation; comammox) is energetically feasible, and it was postulated that this process could occur under conditions selecting for species with lower growth rates but higher growth yields than canonical ammonia-oxidizing microorganisms. Still, organisms catalysing this process have not yet been discovered. Here we report the enrichment and initial characterization of two Nitrospira species that encode all the enzymes necessary for ammonia oxidation via nitrite to nitrate in their genomes, and indeed completely oxidize ammonium to nitrate to conserve energy. Their ammonia monooxygenase (AMO) enzymes are phylogenetically distinct from currently identified AMOs, rendering recent acquisition by horizontal gene transfer from known ammonia-oxidizing microorganisms unlikely. We also found highly similar amoA sequences (encoding the AMO subunit A) in public sequence databases, which were apparently misclassified as methane monooxygenases. This recognition of a novel amoA sequence group will lead to an improved understanding of the environmental abundance and distribution of ammonia-oxidizing microorganisms. Furthermore, the discovery of the long-sought-after comammox process will change our perception of the nitrogen cycle. PMID:26610025

  7. Effect of heavy metals on nitrification performance in different activated sludge processes

    International Nuclear Information System (INIS)

    To understand the toxic effect of heavy metals on the nitrification mechanisms of activated sludge, this study identified the specific ammonia utilization rate (SAUR) inhibited by Pb, Ni and/or Cd shock loadings. Seven different heavy metal combinations (Pb, Ni, Cd, Pb + Ni, Ni + Cd, Pb + Cd, and Pb + Ni + Cd) with seven different heavy metal concentrations (0, 2, 5, 10, 15, 25, and 40 ppm, respectively) were examined by batch experiments, where the activated sludge was taken from either sequencing batch reactor (SBR) or anaerobic-anoxic-oxic (A2O) processes. The experimental results showed the SAUR inhibition rate was Ni > Cd > Pb. No significant inhibition in the nitrification reaction of the activated sludge was observed even when as much as 40 ppm Pb was added. In addition, no synergistic effect was found when different heavy metals were simultaneously added in different concentrations, and the overall inhibition effect depended on the heavy metal with the highest toxicity. Further, first order kinetic reaction could model the behavior of SAUR inhibition on activated sludge when adding heavy metals, and the SAUR inhibition formula was derived as SAUR=(SAURmax-SAURmin)xe-ric+SAURmin. On the other hand, the heavy metal adsorption ability in both the activated sludge system was Pb = Cd > Ni. The specific adsorption capacity of activated sludge on heavy metal increased as the heavy metal concentration increased or the mixed liquid volatile suspended solid (MLVSS) decreased. The batch experiments also showed the heavy metal adsorption capacity of the SBR sludge was larger than the A2O sludge. Finally, the most predominant bacteria in the phylogenetic trees of SBR and A2O activated sludges were proteobacteria, which contributed to 42.1% and 42.8% of the total clones.

  8. An efficient process for wastewater treatment to mitigate free nitrous acid generation and its inhibition on biological phosphorus removal

    Science.gov (United States)

    Zhao, Jianwei; Wang, Dongbo; Li, Xiaoming; Yang, Qi; Chen, Hongbo; Zhong, Yu; An, Hongxue; Zeng, Guangming

    2015-02-01

    Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher phosphorus removal efficiency than the conventional four-step (i.e., anaerobic/oxic/anoxic/oxic) biological nutrient removal process (41 +/- 7% versus 30 +/- 5% in abundance of PAOs and 97 +/- 0.73% versus 82 +/- 1.2% in efficiency of phosphorus removal). It was found that this new process increased pH value but decreased nitrite accumulation, resulting in the decreased FNA generation. Further experiments showed that the new process could alleviate the inhibition of FNA on the metabolisms of PAOs even under the same FNA concentration.

  9. Synthesis, characterization and biological evaluation of anti-cancer indolizine derivatives via inhibiting β-catenin activity and activating p53.

    Science.gov (United States)

    Moon, Seong-Hee; Jung, Youngeun; Kim, Seong Hwan; Kim, Ikyon

    2016-01-01

    Diversity-oriented construction of new indolizine scaffolds was accomplished by utilizing domino Knoevenagel condensation/intramolecular aldol cyclization. Biological evaluation revealed anticancer activity of these compounds through inhibition of β-catenin and activation of p53. PMID:26608553

  10. Combined use of nitrification inhibitor and struvite crystallization to reduce the NH3 and N2O emissions during composting.

    Science.gov (United States)

    Jiang, Tao; Ma, Xuguang; Tang, Qiong; Yang, Juan; Li, Guoxue; Schuchardt, Frank

    2016-10-01

    Struvite crystallization (SCP) is combined with a nitrification inhibitor (dicyandiamide, DCD) to mitigate the NH3 and N2O emission during composting. The MgO and H3PO4 were added at a rate of 15% (mole/mole) of initial nitrogen, and the DCD was added at rates of 0%, 2.5%, 5.0%, 7.5% and 10% (w/w) of initial nitrogen respectively. Results showed that the combination use of SCP and DCD was phytotoxin free. The SCP could significantly reduce NH3 losses by 45-53%, but not the DCD. The DCD significantly inhibits nitrification when the content was higher than 50mgkg(-1), and that could reduce the N2O emission by 76.1-77.6%. The DCD degraded fast during the thermophilic phase, as the nitrification will be inhibited by the high temperature and high free ammonia content in this stage, the DCD was suggested to be applied in the maturing periods by 2.5% of initial nitrogen. PMID:26865057

  11. Thermophilic biological nitrogen removal in industrial wastewater treatment.

    OpenAIRE

    Lopez-Vazquez, CM; Kubare, M.; Saroj, DP; Chikamba, C; Schwarz, J.; Daims, H.; Brdjanovic, D.

    2013-01-01

    Nitrification is an integral part of biological nitrogen removal processes and usually the limiting step in wastewater treatment systems. Since nitrification is often considered not feasible at temperatures higher than 40 °C, warm industrial effluents (with operating temperatures higher than 40 °C) need to be cooled down prior to biological treatment, which increases the energy and operating costs of the plants for cooling purposes. This study describes the occurrence of thermophilic biologic...

  12. Enhanced ammonia removal at room temperature by pH controlled partial nitrification and subsequent anaerobic ammonium oxidation.

    Science.gov (United States)

    Durán, U; del Val Río, A; Campos, J L; Mosquera-Corral, A; Méndez, R

    2014-01-01

    The Anammox-based processes are suitable for the treatment of wastewaters characterized by a low carbon to nitrogen (C/N) ratio. The application of the Anammox process requires the availability of an effluent with a NO2- -N/NH4+ -N ratio composition around 1 g g-1, which involves the necessity of a previous step where the partial nitrification is performed. In this step, the inhibition of the nitrite-oxidizing bacteria (NOB) is crucial. In the present work, a combined partial nitrification-ANaerobic AMmonia OXidation (Anammox) two-units system operated at room temperature (20 degreeC) has been tested for the nitrogen removal of pre-treated pig slurry. To achieve the successful partial nitrification and inhibit the NOB activity, different ammonium/inorganic carbon (NH4+/IC) ratios were assayed from 1.19 to 0.82g NH4+-Ng-1 HCO3-C. This procedure provoked a decrease of the pH value to 6.0 to regulate the inhibitory effect over ammonia-oxidizing bacteria caused by free ammonia. Simultaneously, the NOB experienced the inhibitory effect of free nitrous acid which avoided the presence of nitrate in the effluent. The NH4+/IC ratio which allowed the obtaining of the desired effluent composition (50% of both ammonium and nitrite) was 0.82 +/- 0.02 g NH4+-N g-1 HCO3- -C. The Anammox reactor was fed with the effluent of the partial nitrification unit containing a NO2 -N/NH4+ -N ratio of 1 g g-1' where a nitrogen loading rate of 0.1 g N L-1 d-1 was efficiently removed. PMID:24600878

  13. Aqueous leaf extract of Jatropha gossypiifolia L. (Euphorbiaceae inhibits enzymatic and biological actions of Bothrops jararaca snake venom.

    Directory of Open Access Journals (Sweden)

    Juliana Félix-Silva

    Full Text Available Snakebites are a serious public health problem due their high morbi-mortality. The main available specific treatment is the antivenom serum therapy, which has some disadvantages, such as poor neutralization of local effects, risk of immunological reactions, high cost and difficult access in some regions. In this context, the search for alternative therapies is relevant. Therefore, the aim of this study was to evaluate the antiophidic properties of Jatropha gossypiifolia, a medicinal plant used in folk medicine to treat snakebites. The aqueous leaf extract of the plant was prepared by decoction and phytochemical analysis revealed the presence of sugars, alkaloids, flavonoids, tannins, terpenes and/or steroids and proteins. The extract was able to inhibit enzymatic and biologic activities induced by Bothrops jararaca snake venom in vitro and in vivo. The blood incoagulability was efficiently inhibited by the extract by oral route. The hemorrhagic and edematogenic local effects were also inhibited, the former by up to 56% and the latter by 100%, in animals treated with extract by oral and intraperitoneal routes, respectively. The inhibition of myotoxic action of B. jararaca reached almost 100%. According to enzymatic tests performed, it is possible to suggest that the antiophidic activity may be due an inhibitory action upon snake venom metalloproteinases (SVMPs and/or serine proteinases (SVSPs, including fibrinogenolytic enzymes, clotting factors activators and thrombin like enzymes (SVTLEs, as well upon catalytically inactive phospholipases A2 (Lys49 PLA2. Anti-inflammatory activity, at least partially, could also be related to the inhibition of local effects. Additionally, protein precipitating and antioxidant activities may also be important features contributing to the activity presented. In conclusion, the results demonstrate the potential antiophidic activity of J. gossypiifolia extract, including its significant action upon local effects

  14. Estimates of Denitrification and Nitrification in Coastal and Estuarine Sediments

    OpenAIRE

    Nishio, Takashi; Koike, Isao; Hattori, Akihiko

    1983-01-01

    Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a 15N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N2 evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of nitrifying bacteria in the sediments. At Tama Estuary, the nitrate reduction rate was 11 to 17 times...

  15. Inhibition of a biological sulfide oxidation under haloalkaline conditions by thiols and diorgano polysulfanes

    NARCIS (Netherlands)

    Roman, Pawel; Lipińska, Joanna; Bijmans, Martijn F.M.; Sorokin, Dimitry Y.; Keesman, Karel J.; Janssen, Albert J.H.

    2016-01-01

    A novel approach has been developed for the simultaneous description of reaction kinetics to describe the formation of polysulfide and sulfate anions from the biological oxidation of hydrogen sulfide (H2S) using a quick, sulfide-dependent respiration test. Next to H2S, thiol

  16. Nitrification in premise plumbing and its effect on corrosion and water quality degradation

    OpenAIRE

    Zhang, Yan

    2008-01-01

    Nitrification is increasingly of concern in US potable water systems, due to changes from chlorine to chloramine as a secondary disinfectant in order to comply with new regulations for disinfectant by-products. The ammonia that is released from the chloramine decay supports nitrification. A comprehensive literature review systematically examined the complex inter-relationships between nitrification, materials corrosion and metals release. That analysis suggested that nitrification ...

  17. Nitrification in acid coniferous forests: Some soils do, some soils don't

    OpenAIRE

    Nugroho, R.A.

    2006-01-01

    Nitrification is a key process in the global nitrogen cycle. Ammonia-oxidising bacteria (AOB) were long thought to be the sole microorganisms capable of autotrophic ammonia oxidation, the rate-limited step in nitrification. This thesis elucidates the relation between the presence of AOB, environmental factors and nitrification rates in the soil layer of acid coniferous forests. Especially, the question why some acid forests show nitrification while others do not, is addressed in this thesis.

  18. Conditions and mechanisms affecting simultaneous nitrification and denitrification in a Pasveer oxidation ditch

    NARCIS (Netherlands)

    Hao, X.; Doddema, H.J.; Groenestijn, J.W. van

    1997-01-01

    Simultaneous nitrification and denitrification in a Pasveer oxidation ditch was studied. The purpose was to evaluate the performances of both nitrification and dentrification in oxidation ditches, and to pursue some possible approaches to enhance nitrogen removal. Almost complete nitrification was o

  19. Inhibition effects of high calcium concentration on anaerobic biological treatment of MSW leachate.

    Science.gov (United States)

    Xia, Yi; He, Pin-Jing; Pu, Hong-Xia; Lü, Fan; Shao, Li-Ming; Zhang, Hua

    2016-04-01

    With the increasing use of municipal solid waste incineration (MSWI) and more stringent limits on landfilling of organic waste, more MSWI bottom ash is being landfilled, and the proportion of inorganic wastes in landfills is increasing, causing the increased Ca concentrations in landfill leachate. In this research, the inhibition effect of Ca concentration on the anaerobic treatment of landfill leachate was studied using a biochemical methane potential experiment. Slight inhibition of methane production occurred when the addition of Ca concentration was less than 2000 mg/L. When the addition of Ca concentration was between 6000 and 8000 mg/L, methane production was significantly reduced (to 29.4-34.8 % of that produced by the BLK reactor), and the lag phase was increased from 8.55 to 16.32 d. Moreover, when the dosage of Ca concentration increased from zero to 8000 mg/L, reductions in solution Ca concentration increased from 929 to 2611 mg/L, and the proportion of Ca in the residual sludge increased from 22.58 to 46.87 %. Based on the results, when the dosage of Ca concentration was less than 4000 mg/L, the formation of Ca precipitates on the surface of sludge appeared to prevent mass transfer and was the dominant reason for the reduction in methane production and sludge biomass. At higher Ca concentrations (6000-8000 mg/L), the severe inhibition of methane production appeared to be caused by the toxic effect of highly concentrated Ca on sludge as well as mass transfer blockage. PMID:26769478

  20. Partial Nitrification and Denitrifying Phosphorus Removal in a Pilot-Scale ABR/MBR Combined Process.

    Science.gov (United States)

    Wu, Peng; Xu, Lezhong; Wang, Jianfang; Huang, Zhenxing; Zhang, Jiachao; Shen, Yaoliang

    2015-11-01

    A pilot-scale combined process consisting of an anaerobic baffled reactor (ABR) and an aerobic membrane bioreactor (MBR) for the purpose of achieving easy management, low energy demands, and high efficiencies on nutrient removal from municipal wastewater was investigated. The process operated at room temperature with hydraulic retention time (HRT) of 7.5 h, recycle ratio 1 of 200%, recycle ratio 2 of 100%, and dissolved oxygen (DO) of 1 mg/L and achieved good effluent quality with chemical oxygen demand (COD) of 25 mg/L, NH4 (+)-N of 4 mg/L, total nitrogen (TN) of 11 mg/L, and total phosphorus (TP) of 0.7 mg/L. The MBR achieved partial nitrification, and NO2 (-)-N has been accumulated (4 mg/L). Efficient short-cut denitrification was occurred in the ABR with a TN removal efficiency of 51%, while the role of denitrification and phosphorus removal removed partial TN (14%). Furthermore, nitrogen was further removed (11%) by simultaneous nitrification and denitrification in the MBR. In addition, phosphorus accumulating organisms in the MBR sufficiently uptake phosphorus; thus, effluent TP further reduced with a TP removal efficiency of 84%. Analysis of fluorescence in situ hybridization (FISH) showed that ammonia oxidizing bacteria (AOB) and phosphorus accumulating organisms (PAOs) were enriched in the process. In addition, the accumulation of NO2 (-)-N was contributed to the inhibition on the activities of the NOB rather than its elimination. PMID:26411352

  1. Effects of Heavy Metals on Ammonification,Nitrification and Denitrification in Maize Rhizosphere

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The amrnonification,nitrification and denitrification in maize rhizosphere of alluvial soils were compared with those in the bulk soil after exposure to different kinds of heavy metals.The addition of cadmium at low levels (2 mg kg-1 and 5 mg kg-1) could stimulate the arnmonification and nitrification in the soils,while inhibition influences were found at high levels of Cd addition (10 mg kg-1 and 20 mg kg-1).The relationship between microbial activity and cadmium concentration varied with the kind of microorganisms.The nitrifying bacteria were more sensitive to cadmium pollution than the armonifying bacteria.When Cd(II),Cu(II) and Cr(VI) were compared at the same addition concentration of 20 mg kg-1 soil,Cd(II) was the most effective inhibitor of amronification and denitrification among the three investigated heavy metals,and Cr(VI) had the most strong inhibitory influence on the nitrifying bacteria.The microbial activities in rhizosphere were higher than those in the bulk soil for most of the treatments.Cr(VI) proved to be the most effective in enhancing the microbial activities in rhizosphere,and this could be caused by the positive reduction of Cr(VI) to Cr(III) in rhizosphere,and the relatively sufficient existence of organic matter which intensified the adsorption of the metal.It seemed that the rhizosphere had some mitigation effect on heavy metal toxicity.

  2. A Mini-Nitrification Test for Toxicity Screening, Minntox

    DEFF Research Database (Denmark)

    Arvin, Erik; Dyreborg, Søren; Menck, C.;

    1994-01-01

    There is a high demand for a rapid, simple, and inexpensive test for screening of the toxicity of wastewater, polluted groundwater and chemicals in order to protect sewage treatment plants and aquatic and terrestrial recipients. The mini-nitrification test, MINNTOX, presented here, fulfils this...

  3. Sediment nitrification and denitrification rates in a Lake Superior estuary

    Science.gov (United States)

    Microbially-mediated nitrogen (N) cycling in aquatic sediments has been recognized as an ecosystem service due to mitigation of N-transport to receiving waters. In 2011 and 2012, we compared nitrification (NIT), unamended (DeNIT) and amended (DEA) denitrification rates among spat...

  4. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    NARCIS (Netherlands)

    H. Fan; H. Bolhuis; L.J. Stal

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tida

  5. Effect of low dissolved oxygen on simultaneous nitrification and denitrification in a membrane bioreactor treating black water.

    Science.gov (United States)

    Hocaoglu, S Murat; Insel, G; Cokgor, E Ubay; Orhon, D

    2011-03-01

    Effect of low dissolved oxygen on simultaneous nitrification and denitrification was evaluated in a membrane bioreactor treating black water. A fully aerobic membrane bioreactor was operated at a sludge age of 60 days under three low dissolved oxygen (DO) levels below 0.5mg/L. It sustained effective simultaneous nitrification/denitrification for the entire observation period. Nitrification was incomplete due to adverse effects of a number of factors such as low DO level, SMPs inhibition, alkalinity limitation, etc. DO impact was more significant on denitrification: Nitrate was fully removed at low DO level but the removal was gradually reduced as DO was increased to 0.5mg/L. Nitrogen removal remained optimal within the DO range of 0.15-0.35 mg/L. Experimental results were calibrated and simulated by model evaluation with the same model coefficients. The model defined improved mass transfer with lower affinity coefficients for oxygen and nitrate as compared to conventional activated sludge. PMID:21239168

  6. NITRIFICATION AND NITRIFYING BACTERIA IN A COASTAL MICROBIAL MAT

    Directory of Open Access Journals (Sweden)

    Haoxin eFan

    2015-12-01

    Full Text Available The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA or ammonium-oxidizing bacteria (AOB. We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats.

  7. Ammonia oxidation rates and nitrification in the Arabian Sea

    Science.gov (United States)

    Newell, Silvia E.; Babbin, Andrew R.; Jayakumar, Amal; Ward, Bess B.

    2011-12-01

    Nitrification rates, as well as the relationships between rates and ammonia oxidizer abundance (both archaeal and bacterial), were investigated in the Arabian Sea. Ammonia oxidation rates were measured directly using 15N-NH4+stable isotope additions in gas-impermeable, trace metal clean trilaminate bags (500 mL) at in situ temperature. Tracer incubations were performed at three stations at depths above, below, and within the oxycline of the open-ocean oxygen minimum zone (OMZ). Ammonia oxidation rates were similar to previous open-ocean measurements, ranging from undetectable to 21.6 ± 0.1 nmol L-1 d-1. The highest rates at each station occurred at the primary nitrite maximum (above the OMZ), and rates were very low at depths greater than 900 m. The abundances of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were estimated using theamoA gene by quantitative polymerase chain reaction (qPCR). Both AOA and AOB amoA were detected above, within, and below the OMZ, although the AOA were always more abundant than the AOB, by a factor of 35-216. Nitrification rates were not directly correlated to AOA or AOB amoA abundance. These rates offer new insight into the role of nitrification in the mesopelagic zone. The abundance of AOA amoA genes at 1000 m suggests that ˜50% of the microbial biomass could be autotrophic. Additionally, the integrated nitrification rate at depth implies that nitrification could consume most of the ammonium produced by the flux of organic carbon in the mesopelagic zone.

  8. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    Science.gov (United States)

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature, and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats. PMID:26648931

  9. Nitrification in the Upper Mississippi River: Patterns, controls, and contribution to the NO3- budget

    Science.gov (United States)

    Strauss, E.A.; Richardson, W.B.; Bartsch, L.A.; Cavanaugh, J.C.; Bruesewitz, D.A.; Imker, H.; Heinz, J.A.; Soballe, D.M.

    2004-01-01

    We measured nitrification rates in sediment samples collected from a variety of aquatic habitats in Navigation Pool 8 of the Upper Mississippi River (UMR) 7 times between May 2000 and October 2001. We also conducted nutrient-enrichment experiments and analyzed vertical profiles of sediment to determine factors regulating nitrification. Nitrification rates were relatively high compared to other ecosystems (ranging from 0-8.25 ??g N cm-2 h-1) and exhibited significant temporal and spatial patterns. Nitrification rates were greatest during the summer and spring compared to autumn and winter (ANOVA, p nitrification rates were weakly (r 2 = 0.18, p nitrification in 3 sediment types with variable organic matter. Vertical profiles of sediment cores demonstrated that oxygen concentration and nitrification had similar patterns suggesting that nitrification may be limited by oxygen penetration into sediments. We conclude that temperature and sediment NH4+ can be useful for predicting broad-scale temporal and spatial nitrification patterns, respectively, but oxygen penetration into the sediments likely regulates nitrification rates in much of the UMR. Overall, we estimated that nitrification produces 6982 mt N/y of NO3- or 7% of the total annual NO3- budget.

  10. Removal of organic matter and nitrogen from distillery wastewater by a combination of methane fermentation and denitrification/nitrification processes

    Institute of Scientific and Technical Information of China (English)

    LI Jun; ZHANG Zhen-jia; LI Zhi-rong; HUANG Guang-yu; Naoki Abe

    2006-01-01

    The distillery wastewater of Guangdong Jiujiang Distillery, which is characteristic of containing high organic matters and rich total nitrogen, was treated by a combination of methane fermentation and denitrification/nitrification processes. 80% of COD in the raw wastewater was However, almost all the organic nitrogen in the raw wastewater was converted into ammonia by ammonification there. Ammonia and volatile fatty acids (VFA) remaining in the anaerobically treated wastewater were simultaneously removed utilizing VFA as an electron donor by denitrification occurring in the other EGSB reactor and nitrification using PEG-immobilized nitrifying bacteria with recirculation process. An aerobic biological contact oxidization reactor was designed between denitrification/nitrification reactor for further COD removal. With the above treatment system,18000-28000 mg/L of COD in raw wastewater was reduced to less than 100 mg/L. Also, ammonia in the effluent of the system was not detected and the system had a high removal rate for 900-1200 mg/L of TN in the raw wastewater, only leaving 400 mg/L of nitrate nitrogen.

  11. Simultaneous nitrification, denitrification and phosphorus removal (SNDPR) in a full-scale water reclamation plant located in warm climate.

    Science.gov (United States)

    Yang, Qin; Shen, Nan; Lee, Zarraz M-P; Xu, Guangjing; Cao, Yeshi; Kwok, Beehong; Lay, Winson; Liu, Yu; Zhou, Yan

    2016-01-01

    The combination of simultaneous nitrification-denitrification (SND) with enhanced biological phosphorus removal (EBPR) provides a more efficient and economically viable option for nutrient removal from municipal wastewater compared to conventional two-step nitrification-denitrification. This study analyzed the nutrients (N and P) profiles in a full-scale municipal wastewater reclamation plant (WRP) located in the tropical region, in which more than 90% of nitrogen was removed. Interestingly, average SND efficiency in aerobic zones was found to be up to 50%, whereas phosphorus profile displayed a clear cyclic release and uptake pattern with a phosphorus removal efficiency of up to 76%. The capability of sludge to perform SND and EBPR was further confirmed through a series of batch experiments. Microbial analysis revealed the presence of Accumulibacter and Tetrasphaera phosphate accumulating organisms in the plant, while few glycogen accumulating organisms (GAO) was observed. This study showed the significant occurrence of combined SND and EBPR, known as simultaneous nitrification, denitrification and phosphorus removal (SNDPR), in the studied WRP under warm climate. The possible causes behind the observed SNDPR were also discussed. PMID:27438250

  12. Regulatory inhibition of biological tissue mineralization through post-nucleation shielding

    Science.gov (United States)

    Chang, Joshua; Miura, Robert

    In vertebrates, insufficient availability of calcium and phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are present at high concentrations throughout body fluids - at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. We adapted mean-field classical nucleation theory to the case of surface-shielding in order to study the regulation of sedimentation of calcium phosphate salts in biological tissues. Mathematical Biosciences Institute, NSF DMS-1021818, National Institutes of Health, Rehab Medicine.

  13. The Effects of Osmotic Potential on Ammonification, Immobilization, Nitrous Oxide Production, and Nitrification Rates in Penoyer Soil

    OpenAIRE

    Low, Andrew P.

    1996-01-01

    An isotopic dilution method was used to test the effects of osmotic potential, (IJ' ,), upon nitrification, ammonification, N-immobilization, and nitrous oxide production rates in soil at solute concentrations encountered in Penoyer soil. A nitrification potential assay was also performed to approximate maximum nitrification rates. Nitrification potential rates in soil slurries exponentially declined in response to decreased osmotic potential. However, nitrification was independent of salt...

  14. Nitrification and N2O production processes in soil incubations after ammonium fertilizer application at high concentrations

    Science.gov (United States)

    Deppe, Marianna; Well, Reinhard; Giesemann, Anette; Flessa, Heinz

    2016-04-01

    High concentrations of ammonium as they occur, e.g., after point-injection of ammonium fertilizer solution according to the CULTAN fertilization technique may retard nitrification. Potential advantages in comparison to conventional fertilization include a higher N efficiency of crops, reduced nitrate leaching, and lower N2O and N2 emissions. Dynamics of nitrification due to plant uptake and dilution processes, leading to decreasing ammonium concentrations in fertilizer depots, has only poorly been studied before. Furthermore, there is little information about the relative contribution of different N2O production processes under these conditions. To elucidate the process dynamics a laboratory incubation study was conducted. After fertilization with ammonium sulfate at 5 levels (from 0 to 5000 mg NH4+-N kg‑1; 20mg NO3‑-N kg‑1 each), sandy loam soil was incubated in dynamic soil microcosms for 21 days. N2O, CH4 and CO2 fluxes as well as isotope signatures of N2O and, at three dates, NO3‑ and NH4+ were measured. To identify N2O production processes, acetylene inhibition (0.01 vol.%), 15N tracer approaches, and isotopomer data (15N site preference and δ18O) were used. N2O emissions were highest at 450mg NH4+-N kg‑1 and declined with further increasing concentrations. At 5000 mg NH4+-N kg‑1 nitrification was completely inhibited. However, approximately 90% of N2O production was inhibited by acetylene application, and there was no change in the relative contribution of nitrification and denitrification to N2O production with N level. Applying the non-equilibrium technique to our 15N tracer data revealed heterogeneous distribution of denitrification in soil, with at least two distinct NO3‑ pools, and spatial separation of NO3‑ formation and consumption. In comparison with the acetylene inhibition and 15N tracer approaches the results of the isotopomer approach were reasonable and indicated substantial contribution of nitrifier-denitrification (10-40%) to

  15. Biologic

    CERN Document Server

    Kauffman, L H

    2002-01-01

    In this paper we explore the boundary between biology and the study of formal systems (logic). In the end, we arrive at a summary formalism, a chapter in "boundary mathematics" where there are not only containers but also extainers ><, entities open to interaction and distinguishing the space that they are not. The boundary algebra of containers and extainers is to biologic what boolean algebra is to classical logic. We show how this formalism encompasses significant parts of the logic of DNA replication, the Dirac formalism for quantum mechanics, formalisms for protein folding and the basic structure of the Temperley Lieb algebra at the foundations of topological invariants of knots and links.

  16. Determination of respiration, gross nitrification and denitrification in soil profile using BaPS system

    Institute of Scientific and Technical Information of China (English)

    CHEN Shu-tao; HUANG Yao

    2006-01-01

    A facility of BaPS (Barometric Process Separation) was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7-14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass (P<0.001).

  17. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    OpenAIRE

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is presen...

  18. NITRIFICATION AND NITRIFYING BACTERIA IN A COASTAL MICROBIAL MAT

    OpenAIRE

    Haoxin eFan; Henk eBolhuis; Lucas eStal

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is presen...

  19. Ancient landscapes and the relationship with microbial nitrification.

    Science.gov (United States)

    Jenkins, Sasha N; Murphy, Daniel V; Waite, Ian S; Rushton, Steven P; O'Donnell, Anthony G

    2016-01-01

    Ammonia oxidizing archaea (AOA) and bacteria (AOB) drive nitrification and their population dynamics impact directly on the global nitrogen cycle. AOA predominate in the majority of soils but an increasing number of studies have found that nitrification is largely attributed to AOB. The reasons for this remain poorly understood. Here, amoA gene abundance was used to study the distribution of AOA and AOB in agricultural soils on different parent materials and in contrasting geologic landscapes across Australia (n = 135 sites). AOA and AOB abundances separated according to the geologic age of the parent rock with AOB higher in the more weathered, semi-arid soils of Western Australia. AOA dominated the younger, higher pH soils of Eastern Australia, independent of any effect of land management and fertilization. This differentiation reflects the age of the underlying parent material and has implications for our understanding of global patterns of nitrification and soil microbial diversity. Western Australian soils are derived from weathered archaean laterite and are acidic and copper deficient. Copper is a co-factor in the oxidation of ammonia by AOA but not AOB. Thus, copper deficiency could explain the unexpectedly low populations of AOA in Western Australian soils. PMID:27480661

  20. Arachidonic acid drives postnatal neurogenesis and elicits a beneficial effect on prepulse inhibition, a biological trait of psychiatric illnesses.

    Directory of Open Access Journals (Sweden)

    Motoko Maekawa

    Full Text Available Prepulse inhibition (PPI is a compelling endophenotype (biological markers for mental disorders including schizophrenia. In a previous study, we identified Fabp7, a fatty acid binding protein 7 as one of the genes controlling PPI in mice and showed that this gene was associated with schizophrenia. We also demonstrated that disrupting Fabp7 dampened hippocampal neurogenesis. In this study, we examined a link between neurogenesis and PPI using different animal models and exploring the possibility of postnatal manipulation of neurogenesis affecting PPI, since gene-deficient mice show biological disturbances from prenatal stages. In parallel, we tested the potential for dietary polyunsaturated fatty acids (PUFAs, arachidonic acid (ARA and/or docosahexaenoic acid (DHA, to promote neurogenesis and improve PPI. PUFAs are ligands for Fabp members and are abundantly expressed in neural stem/progenitor cells in the hippocampus. Our results are: (1 an independent model animal, Pax6 (+/- rats, exhibited PPI deficits along with impaired postnatal neurogenesis; (2 methylazoxymethanol acetate (an anti-proliferative drug elicited decreased neurogenesis even in postnatal period, and PPI defects in young adult rats (10 weeks when the drug was given at the juvenile stage (4-5 weeks; (3 administering ARA for 4 weeks after birth promoted neurogenesis in wild type rats; (4 raising Pax6 (+/- pups on an ARA-containing diet enhanced neurogenesis and partially improved PPI in adult animals. These results suggest the potential benefit of ARA in ameliorating PPI deficits relevant to psychiatric disorders and suggest that the effect may be correlated with augmented postnatal neurogenesis.

  1. Impact of nitrite on aerobic phosphorus uptake by poly-phosphate accumulating organisms in enhanced biological phosphorus removal sludges.

    Science.gov (United States)

    Zeng, Wei; Li, Boxiao; Yang, Yingying; Wang, Xiangdong; Li, Lei; Peng, Yongzhen

    2014-02-01

    Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5% of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10(-3) mg HNO₂-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10(-3) mg HNO2-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10(-3) and 2.13 × 10(-3) mg HNO₂-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite. PMID:23771179

  2. The Influence of Mineral Fertilizer Combined With a Nitrification Inhibitor on Microbial Populations and Activities in Calcareous Uzbekistanian Soil Under Cotton Cultivation

    Directory of Open Access Journals (Sweden)

    Dilfuza Egamberdiyeva

    2001-01-01

    Full Text Available Application of fertilizers combined with nitrification inhibitors affects soil microbial biomass and activity. The objective of this research was to determine the effects of fertilizer application combined with the nitrification inhibitor potassium oxalate (PO on soil microbial population and activities in nitrogen-poor soil under cotton cultivation in Uzbekistan. Fertilizer treatments were N as urea, P as ammophos, and K as potassium chloride. The nitrification inhibitor PO was added to urea and ammophos at the rate of 2%. Three treatments—N200P140K60 (T1, N200 P140 POK60 (T2, and N200 P140 POK60 (T3 mg kg-1 soil—were applied for this study. The control (C was without fertilizer and PO. The populations of oligotrophic bacteria, ammonifying bacteria, nitrifying bacteria, denitrifying bacteria, mineral assimilating bacteria, oligonitrophilic bacteria, and bacteria group Azotobacter were determined by the most probable number method. The treatments T2 and T3 increased the number of oligonitrophilic bacteria and utilization mineral forms of nitrogen on the background of reducing number of ammonifying bacteria. T2 and T3 also decreased the number of nitrifying bacteria, denitrifying bacteria, and net nitrification. In conclusion, our experiments showed that PO combined with mineral fertilizer is one of the most promising compounds for inhibiting nitrification rate, which was reflected in the increased availability and efficiency of fertilizer nitrogen to the cotton plants. PO combined with mineral fertilizer has no negative effects on nitrogen-fixing bacteria Azotobacter and oligo-nitrophilic bacteria.

  3. N2O emissions from a cultivated Andisol after application of nitrogen fertilizers with or without nitrification inhibitor under soil moisture regime

    Institute of Scientific and Technical Information of China (English)

    FAN Xiao-hui; Haruo Tsuruta

    2004-01-01

    The aim of this work was to examine the emission of N2O from soils following addition of nitrogen fertilizer with a nitrification inhibitor(+inh) or without the nitrification inhibitor(-inh) at different soil water regime. Higher soil moisture contents increased the total N2O emissions in all treatments with total emissions being 7 times larger for the CK and >20 times larger for the fertilizer treatments at 85% WFPS(soil water filled pore space ) than at 40% WFPS. The rates of N2O emissions at 40% WFPS under all treatments were small. The maximum emission rate at 55% WFPS without the nitrification inhibitor(-inh) occurred later (day 11) than those of 70% WFPS (-inh) samples (day 8). The inhibition period was 4-22 d for 55% WFPS and 1-15 d for 70% WFPS comparing the rates of N2O emissions treated (+inh) with (-inh). The maximum emission rates at 85% WFPS were higher than those at the other levels of soil water content for all treatments. The samples(+inh) released less N2O than (-inh) samples at the early stage. Nevertheless, N2O emissions from (+inh) samples lasted longer than in the (-inh) treatment. Changes in mineral N at 55%, 70% and 85% WFPS followed the same pattern. NH4-N concentrations decreased while NO3-N concentrations increased from the beginning of incubation. NH4-N concentrations from 40% WFPS treatment declined more slowly than those of the other three levels of soil water content. Nitrification was faster in the (-inh) samples with 100% NH4-N nitrified after 22 d(50% WFPS ) and 15 d(70% and 85% WFPS). N2O emissions increased with soil water content. Adding N-fertilizer increased emissions of N2O. The application of the nitrification inhibitor significantly reduced total N2O emissions from 30.5%(at 85%WFPS) to 43.6%(at 55% WFPS).

  4. N2:O emissions from a cultivated Andisol after application of nitrogen fertilizers with or without nitrification inhibitor under soil moisture regime.

    Science.gov (United States)

    Fan, Xiao-Hui; Haruo, Tsuruta

    2004-01-01

    The aim of this work was to examine the emission of N2O from soils following addition of nitrogen fertilizer with a nitrification inhibitor (+inh) or without the nitrification inhibitor(-inh) at different soil water regime. Higher soil moisture contents increased the total N2O emissions in all treatments with total emissions being 7 times larger for the CK and > 20 times larger for the fertilizer treatments at 85% WFPS (soil water filled pore space) than at 40% WFPS. The rates of N2O emissions at 40% WFPS under all treatments were small. The maximum emission rate at 55% WFPS without the nitrification inhibitor (-inh) occurred later (day 11) than those of 70% WFPS (-inh) samples (day 8). The inhibition period was 4-22 d for 55% WFPS and 1-15 d for 70% WFPS comparing the rates of N2O emissions treated (+inh) with (-inh). The maximum emission rates at 85% WFPS were higher than those at the other levels of soil water content for all treatments. The samples (+inh) released less N2O than (-inh) samples at the early stage. Nevertheless, N2O emissions from (+inh) samples lasted longer than in the (-inh) treatment. Changes in mineral N at 55%, 70% and 85% WFPS followed the same pattern. NH4(+) -N concentrations decreased while NO3(-) -N concentrations increased from the beginning of incubation. NH4(+) -N concentrations from 40% WFPS treatment declined more slowly than those of the other three levels of soil water content. Nitrification was faster in the (-inh) samples with 100% NH4(+) -N nitrified after 22 d (50% WFPS) and 15 d (70% and 85% WFPS). N2O emissions increased with soil water content. Adding N-fertilizer increased emissions of N2O. The application of the nitrification inhibitor significantly reduced total N2O emissions from 30.5% (at 85% WFPS) to 43.6% (at 55% WFPS). PMID:15559801

  5. Effect of nitrogen on phosphate reduction in biological phosphorus removal from wastewater

    OpenAIRE

    Vabolienė, Giedrė; Matuzevičius, Algimantas B.; Valentukevičienė, Marina

    2007-01-01

    Conventional schemes of biological nitrogen removal can be combined with phosphorus removal schemes. One of the common technology schemes for biological nitrogen removal is the aeration zone and the anoxic zone in one tank. The nitrification and denitrification are carried out during the aeration switching on and off. The anaerobic zone is equipped behind the nitrification/denitrification tank for biological phosphorus removal. Exchange of the anaerobic and aerobic conditions is necessary for...

  6. Nitrogen removal from landfill leachate via ex situ nitrification and sequential in situ denitrification

    International Nuclear Information System (INIS)

    Ex situ nitrification and sequential in situ denitrification represents a novel approach to nitrogen management at landfills. Simultaneous ammonia and organics removal was achieved in a continuous stirred tank reactor (CSTR). The results showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l-1 d-1 and 3.84 g COD l-1 d-1, respectively. The ammonia and chemical oxygen demand (COD) removal was over 99% and 57%, respectively. In the run of the CSTR, free ammonia (FA) inhibition and low dissolved oxygen (DO) were found to be key factors affecting nitrite accumulation. In situ denitrification was studied in a municipal solid waste (MSW) column by recalculating nitrified leachate from CSTR. The decomposition of MSW was accelerated by the recirculation of nitrified leachate. Complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON loading of 28.6 g N t-1 TS d-1 and denitrification was the main reaction responsible. Additionally, methanogenesis inhibition was observed while TON loading was over 11.4 g N t-1 TS d-1 and the inhibition was enhanced with the increase of TON loading

  7. Apparent and Measured Rates of Nitrification in the Hypolimnion of a Mesotrophic Lake

    OpenAIRE

    Hall, Grahame H.

    1982-01-01

    Three distinct phases were observed in the change of dissolved inorganic nitrogen concentrations in the hypolimnion of Grasmere. The second phase of decreasing ammonia and increasing nitrate concentrations was typical of the nitrification process. Observations on nitrate concentration gradients between surface sediments and the water column and experiments using the nitrification inhibitor N-Serve indicated the in situ activity of chemolithotrophic nitrifying organisms. Nitrification rates we...

  8. N-Tox® - Early warning of nitrification toxicity for activated sludge treatment

    OpenAIRE

    Callister, S.; Stephenson, Tom; Butler, M. D.; Cartmell, Elise

    2006-01-01

    N-Tox® is a new technique for evaluating the nitrification efficiency in industrial or municipal activated sludge systems, using direct measurement of nitrous oxide (N20) as an indicator of nitrification failure. Research using pilot-scale activated sludge plants treating real settled wastewater has demonstrated that detection of increased N2O concentration in the aeration tanks by N-Tox® is able to provide early warning of nitrification failure. The N-Tox® monitor relies on...

  9. Quantification of Ammonia-Oxidizing Bacteria and Factors Controlling Nitrification in Salt Marsh Sediments

    OpenAIRE

    Dollhopf, Sherry L.; Hyun, Jung-Ho; Smith, April C.; Adams, Harold J.; O'Brien, Sean; Kostka, Joel E.

    2005-01-01

    To elucidate the geomicrobiological factors controlling nitrification in salt marsh sediments, a comprehensive approach involving sediment geochemistry, process rate measurements, and quantification of the genetic potential for nitrification was applied to three contrasting salt marsh habitats: areas colonized by the tall (TS) or short (SS) form of Spartina alterniflora and unvegetated creek banks (CBs). Nitrification and denitrification potential rates were strongly correlated with one anoth...

  10. Influence of dissolved oxygen in nitrification kinetics in a circulating bed reactor

    OpenAIRE

    V. Lazarova; R. Nogueira; J. Manem; Melo, L. F.

    1997-01-01

    The influence of dissolved oxygen concentration in nitrification kinetics was studied in a new biofilm reactor, the circulating bed reactor (CBR). The study was carried out partly at laboratory scale with synthetic water containing inorganic carbon and nitrogen compounds, and partly at pilot scale for secondary and tertiary nitrification of municipal wastewater. The experimental results showed that, either the ammonia or the oxygen concentration could be limiting for the nitrification rate...

  11. Significance of archaeal nitrification in hypoxic waters of the Baltic Sea

    OpenAIRE

    Berg, Carlo; Vandieken, Verona; Thamdrup, Bo; Jürgens, Klaus

    2014-01-01

    Ammonia-oxidizing archaea (AOA) of the phylum Thaumarchaeota are widespread, and their abundance in many terrestrial and aquatic ecosystems suggests a prominent role in nitrification. AOA also occur in high numbers in oxygen-deficient marine environments, such as the pelagic redox gradients of the central Baltic Sea; however, data on archaeal nitrification rates are scarce and little is known about the factors, for example sulfide, that regulate nitrification in this system. In the present wo...

  12. The side effects of nitrification inhibitors on leaching water and soil salinization in a field experiment

    Energy Technology Data Exchange (ETDEWEB)

    Diez, J. A.; Arauzo, M.; Hernaiz, P.; Sanz, A.

    2010-07-01

    In experiments carried out in greenhouses, some authors have shown that ammonium sulphate induces greater soil acidity and salinity than other sources of N. Moreover, nitrification inhibitors (NI) tend to cause ammonium to accumulate in soil by retarding its oxidation to nitrate. This accumulated ammonium would also have an effect on soil salinity. Consequently, the aim of this paper was to evaluate the soil and leaching water salinization effects associated with adding NI, dicyandiamide (DCD) and dimethylpyrazole-phosphate (DMPP) to ammonium sulphate nitrate (ASN) fertilizer. This experiment was carried out in the field with an irrigated maize crop. Drainage and Na concentration were measured during both seasons (2006 and 2007) and leached Na was determined. The treatments with NI (DCD and DMPP) were associated with greater Na concentrations in soil solutions and consequently higher rates of Na leaching (in 2007, ASN-DCD 1,292 kg Na ha{sup -}1, ASN-DMPP 1,019 kg Na ha{sup -}1). A treatment involving only ASN also increased the Na concentration in soil and the amount of Na leached in relation to the Control (in 2007, ASN 928 kg Na ha{sup -}1 and Control 587 kg Na ha{sup -}1). The increase in the ammonium concentration in the soil due to the NI treatments could have been the result of the displacement of Na ions from the soil exchange complex through a process which finally led to an increase in soil salinity. Treatments including ammonium fertilizer formulated with NI produced a greater degree of soil salinization due to the presence of ammonium from the fertilizer and accumulated ammonium from the nitrification inhibition. (Author) 31 refs.

  13. Effects of polybrominated diphenyl ethers and plant species on nitrification, denitrification and anammox in mangrove soils.

    Science.gov (United States)

    Chen, Juan; Zhou, Hai Chao; Pan, Ying; Shyla, Farzana Shazia; Tam, Nora Fung-Yee

    2016-05-15

    Little is known about polybrominated diphenyl ethers (PBDEs) and planting affect biogeochemical processes, and their impact on microbial nitrogen (N) transformation in soil. A 12-month microcosm experiment was conducted to understand the effects of a mixture of PBDEs at two contamination levels, 2 and 20 mg kg(-1)dry weight representing low and high soil contamination, respectively, using two mangrove plant species, namely Kandelia obovata (Ko) and Bruguiera gymnorrhiza (Bg), on nitrification, denitrification and anammox in mangrove soils. No significant changes in these N transformation processes were found at month 3 and at a low level of PBDEs in both plant species, suggesting that short-term exposure to 2 mg kg(-1) contamination did not affect microbial N transformation. At month 12, a high level of PBDE contamination significantly decreased the nitrification potential activity and the copy numbers of archaeal amoA and bacterial amoA gene in Ko soil, but such inhibitory effect was not significant in Bg soil. On the contrary, the denitrification-related parameters, including the activities of nitrate reductase and nitrite reductase, potential denitrification activity and copy numbers of nirK, nirS and nosZ gene, were stimulated by a high level of PBDE contamination in both Ko and Bg soils, and the stimulation was higher in the more anaerobic Bg soil. Different from denitrification, a high level of PBDE contamination decreased the copy numbers of anammox bacterial 16S rRNA gene in Bg soil but not in Ko soil; this was possibly related to the lower nitrate concentration in Bg soil that might inhibit the growth of anammox bacteria. These results indicated that the effects of PBDEs on microbial N transformation were plant species-specific, with the nitrifying microorganisms in Ko soil more susceptible to PBDE contamination, while denitrification and anammox in Bg soil were more sensitive. PMID:26901803

  14. Epilithic biofilms as hotspots of in-stream nitrification in a high N loaded urban stream

    Science.gov (United States)

    Bernal, S.; Merbt, S. N.; Ribot, M.; Casamayor, E. O.; Martí Roca, E.

    2015-12-01

    Nitrification, the oxidation of ammonia to nitrate, is one of the most important biogeochemical processes in high nitrogen loaded urban streams. The first rate-limiting step of the nitrification process is carried out by ammonia-oxidizing (AO) archaea (AOB) and bacteria (AOB) that live in stream sediments and epilithic biofilms. Yet, the relative contribution of these two stream habitats to whole-reach nitrification is largely unknown. We tested the well-established idea that whole-reach nitrification is mainly driven by AO present in hyporheic sediments because of their relative high active surface area compared to the thin epilithic biofilm interface. To do so, we examined substrata-specific nitrification rates and AO transcripts abundance (amoA gene) in mesocosms and scaled data to whole reach. Further, we compared the scaled data to in situ whole-reach nitrification rates and amoA transcript and gene abundances in a high N loaded urban stream downstream of a waste water treatment plant effluent. Against expectations, whole-reach in-stream nitrification was mainly driven by AOB embedded in biofilms growing on the sediment-facing side (> 60%) and light-exposed side (20%) of stream cobbles. Hyporheic sediments, which were mainly colonized by AOA, accounted for 11% of in situ whole-reach nitrification. Our study points epilithic biofilms as hot spots of nitrification within urban stream ecosystems.

  15. 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.

  16. Effectiveness of 3,4-Dimethylpyrazole Phosphate as Nitrification Inhibitor in Soil as Influenced by Inhibitor Concentration,Application Form,and Soil Matric Potential

    Institute of Scientific and Technical Information of China (English)

    G.BARTH; S.VON TUCHER; U.SCHMIDHALTER

    2008-01-01

    The efficacy of nitrification inhibitors depends on soil properties and environmental conditions.The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) was investigated in a sandy loam and a loamy soil to study its effectiveness as influenced by inhibitor concentration,application form,and soil matric potential.DMPP was applied with concentrations up to 34.6 mg DMPP kg-1 soil as solution or as ammonium-sulfate/ammonium-nitrate granules formulated with DMPP.DMPP inhibited the oxidation of ammonium in both soils,but this effect was more pronounced in the sandy loam than in the loamy soil When applied as solution,increasing DMPP concentrations up to 7 mg DMPP kg-1 soil had no influence on the inhibition.The effectiveness of DMPP formulated as fertilizer granules was superior to the liquid application of DMPP and NH+,particularly in the loamy soil.Without DMPP,a decline in soil matric potential down to -600 kPa decreased nitrification in both soils,but this effect was more pronounced in the sandy loam than in the loamy soil.DMPP was most effective in the sandy loam particularly under conditions of higher soil moisture,i.e.,under conditions favorable for nitrate leaching.

  17. Influence of dose rate on fast neutron OER and biological effectiveness determined for growth inhibition in Vicia faba

    International Nuclear Information System (INIS)

    The influence of dose rate on the effectiveness of a neutron irradiation was investigated using growth inhibition in Vicia faba bean roots as biological system. d(50)+Be neutron beams produced at the cyclotron CYCLONE of the University of Louvain-la-Neuve were used, at high and low dose rate, by modifying the deuteron beam current. When decreasing the dose rate from 0.14 Gy.min-1 to 0.2 Gy.h-1, the effectiveness of the neutrons decreased down to 0.84+-0.05 (dose ratio, at high and low dose rate, Dsub(high)/Dsub(low), producing equal biological effect). Control irradiation, with 60Co γ-rays, indicated a similar reduction in effectiveness (0.84+-0.03) when decreasing dose rate from 0,6 Gy.min-1 to 0.7 Gy.h-1. In previous experiments, on the same Vicia faba system, higher RBE values were observed for 252Cf neutrons, at low dose rate (RBE=8.3), compared to different neutron beams actually used in external beam therapy (RBE=3.2-3.6 for d(50)+Be, p(75)+Be and 15 MeV (d, T) neutrons). According to present results, this higher RBE has to be related to lower energy of the 252Cf neutron spectrum (2 MeV), since the influence of dose rate was shown to be small. As far as OER is concerned, for d(50)+Be neutrons, it decreases from 1.65+-0.12 to 1.59+-0.09 when decreasing close rate from 0.14 Gy.min-1 to 0.2 Gy.h-1. Control irradiations with 60Co γ-rays have shown an OER decrease from 2.69+-0.08 to 2.55+-0.11 when decreasing dose rate from 0.6 Gy.min-1 to 0.7 Gy.h-1. These rather small OER reductions are within the statistical fluctuations. (orig.)

  18. 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.

  19. Phylogenetically distinct phylotypes modulate nitrification in a paddy soil.

    Science.gov (United States)

    Zhao, Jun; Wang, Baozhan; Jia, Zhongjun

    2015-05-01

    Paddy fields represent a unique ecosystem in which regular flooding occurs, allowing for rice cultivation. However, the taxonomic identity of the microbial functional guilds that catalyze soil nitrification remains poorly understood. In this study, we provide molecular evidence for distinctly different phylotypes of nitrifying communities in a neutral paddy soil using high-throughput pyrosequencing and DNA-based stable isotope probing (SIP). Following urea addition, the levels of soil nitrate increased significantly, accompanied by an increase in the abundance of the bacterial and archaeal amoA gene in microcosms subjected to SIP (SIP microcosms) during a 56-day incubation period. High-throughput fingerprints of the total 16S rRNA genes in SIP microcosms indicated that nitrification activity positively correlated with the abundance of Nitrosospira-like ammonia-oxidizing bacteria (AOB), soil group 1.1b-like ammonia-oxidizing archaea (AOA), and Nitrospira-like nitrite-oxidizing bacteria (NOB). Pyrosequencing of 13C-labeled DNA further revealed that 13CO2 was assimilated by these functional groups to a much greater extent than by marine group 1.1a-associated AOA and Nitrobacter-like NOB. Phylogenetic analysis demonstrated that active AOB communities were closely affiliated with Nitrosospira sp. strain L115 and the Nitrosospira multiformis lineage and that the 13C-labeled AOA were related to phylogenetically distinct groups, including the moderately thermophilic "Candidatus Nitrososphaera gargensis," uncultured fosmid 29i4, and acidophilic "Candidatus Nitrosotalea devanaterra" lineages. These results suggest that a wide variety of microorganisms were involved in soil nitrification, implying physiological diversification of soil nitrifying communities that are constantly exposed to environmental fluctuations in paddy fields. PMID:25724959

  20. Alteration of Oceanic Nitrification Under Elevated Carbon Dioxide Concentrations

    Science.gov (United States)

    Beman, J.; Chow, C. E.; Popp, B. N.; Fuhrman, J. A.; Feng, Y.; Hutchins, D. A.

    2008-12-01

    Atmospheric carbon dioxide (CO2) concentrations are increasing exponentially and expected to double by the year 2100. Dissolution of excess CO2 in the upper ocean reduces pH, alters carbonate chemistry, and also represents a potential resource for autotrophic organisms that convert inorganic carbon into biomass--including a broad spectrum of marine microbes. These bacteria and archaea drive global biogeochemical cycles of carbon and nitrogen and constitute the vast majority of biomass in the sea, yet their responses to reduced pH and increased pCO2 remain largely undocumented. Here we show that elevated pCO2 may sharply reduce nitrification rates and populations of nitrifying microorganisms in the ocean. Multiple experiments were performed in the Sargasso Sea and the Southern California Bight under glacial maximum (193 ppm), present day (390 ppm), and projected (750 ppm) pCO2 concentrations, over time scales from hours to multiple days, and at depths of 45 m to 240 m. Measurement of nitrification rates using isotopically-labeled nitrogen showed 2-5 fold reduction under elevated pCO2--as well as an increase under glacial maximum pCO2. Marine Crenarchaeota are likely involved in nitrification as ammonia-oxidizing archaea (AOA) and are among the most abundant microbial groups in the ocean, yet this group decreased by 40-80% under increased pCO2, based on quantification of both 16S rRNA and ammonia monooxygenase (amoA) gene copies. Crenarchaeota also steadily declined over the course of multiple days under elevated pCO2, whereas ammonia-oxidizing (AOB) and nitrite-oxidizing bacteria (NOB) were more variable in their responses or were not detected. These findings suggest that projected increases in pCO2 and subsequent decreases in pH may strongly influence marine biogeochemistry and microbial community structure in the sea.

  1. Bioaugmentation to improve nitrification in activated sludge treatment.

    Science.gov (United States)

    Leu, Shao-Yuan; Stenstrom, Michael K

    2010-06-01

    Bioaugmentation is a proposed technique to improve nutrient removal in municipal wastewater treatment. Compared with commonly used nitrification/denitrification (NDN) processes, bioaugmentation may be able to reduce tankage or land requirements. Many approaches for bioaugmentation have been developed, but few studies have compared the benefits among different approaches. This paper quantifies the effectiveness of bioaugmentation processes and investigates three major "onsite" bioaugmentation alternatives: 1) the parallel-plants approach, which uses acclimated biomass grown in a nitrifying "long-SRT" (sludge retention time) plant to augment a low-SRT treatment plant; 2) the enricher-reactor approach, which uses an offline reactor to produce the augmentation cultures; and 3) the enricher-reactor/return activated sludge (ER-RAS) approach, which grows enrichment culture in a reaeration reactor that receives a portion of the recycle activated sludge. Kinetic models were developed to simulate each approach, and the benefits of various approaches are presented on the same basis with controllable parameters, such as bioaugmentation levels, aeration tank volume, and temperatures. Examples were given to illustrate the potential benefits of bioaugmentation by upgrading a "carbon-only" wastewater treatment plant to nitrification. Simulation results suggested that all bioaugmentation approaches can decrease the minimum SRT for nitrification. The parallel-plants approach creates the highest concentration of biomass but may fail at too low temperature. The ER-RAS approach likely would be more useful at lower temperature and required less reactor volume; enricher-reactor approach would likely be more advantageous in the presence of inhibitory compound(s). PMID:20572460

  2. Analysis of the impact of reflux ratio on coupled partial nitrification-anammox for co-treatment of mature landfill leachate and domestic wastewater.

    Science.gov (United States)

    Wu, Lina; Zhang, Lieyu; Shi, Xiao; Liu, Ting; Peng, Yongzhen; Zhang, Jie

    2015-12-01

    A combined system of anaerobic-aerobic techniques was used for deep co-treatment of mature landfill leachate and domestic sewage, mixed at a ratio of 1:5, through partial nitrification-anammox. While ensuring synchronous removal of organic matter and nitrogen, we investigated changes in several factors under different reflux ratios (0%, 100% and 300%). High nitrification efficiency and a relatively high accumulation rate of NO2(-)-N were achieved, the latter through selective inhibition of bacteria by free ammonia. The results indicated that maintaining the reflux ratio within an optimum range contributes to the enrichment of anammox bacteria. In this study, the optimum ratio, which permitted the highest removal rates of chemical oxygen demand (COD), NH4(+)-N, and total nitrogen, was 300%. The COD level in the anammox reactor (ANAOR) decreased to lower than 70 mg/L, resulting in no inhibitory effect on anammox and maximum enrichment of bacteria. PMID:26386424

  3. Transport zonation limits coupled nitrification-denitrification in permeable sediments

    DEFF Research Database (Denmark)

    Kessler, Adam John; Glud, R.N.; Cardenas, M.B.;

    2013-01-01

    -dimensional distributions of NO3- and N-15-N-2 gas. The measured two-dimensional profiles correlate with computational model simulations, showing a deep pool of N-2 gas forming, and being advected to the surface below ripple peaks. Further isotope pairing calculations on these data indicate that coupled nitrification......-denitrification is severely limited in permeable sediments because the flow and transport field limits interaction between oxic and anoxic pore water. The approach allowed for new detailed insight into subsurface denitrification zones in complex permeable sediments....

  4. Links among nitrification, nitrifier communities and edaphic properties in contrasting soils receiving dairy slurry

    Science.gov (United States)

    Soil biotic and abiotic factors strongly influence nitrogen (N) availability and increases in nitrification rates associated with the application of manure. In this study, we examine the effects of edaphic properties and a dairy (Bos taurus) slurry amendment on N availability, nitrification rates an...

  5. 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.

  6. Nitrification in acid coniferous forests: Some soils do, some soils don't

    NARCIS (Netherlands)

    Nugroho, R.A.

    2006-01-01

    Nitrification is a key process in the global nitrogen cycle. Ammonia-oxidising bacteria (AOB) were long thought to be the sole microorganisms capable of autotrophic ammonia oxidation, the rate-limited step in nitrification. This thesis elucidates the relation between the presence of AOB, environmen

  7. An Operations Manual for Achieving Nitrification in an Activated Sludge Plant.

    Science.gov (United States)

    Ontario Ministry of the Environment, Toronto.

    In Ontario, the attainment of nitrification (oxidation of ammonia) in activated sludge plants is receiving increased attention. Nitrification of waste water is a necessary requirement because it reduces plant discharge of nitrogenous oxygen demand and/or toxic ammonia. However, this new requirement will result in added responsibility for…

  8. 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

  9. Biosensor Determination of the Microscale Distribution of Nitrate, Nitrate Assimilation, Nitrification, and Denitrification in a Diatom-Inhabited Freshwater Sediment

    OpenAIRE

    Lorenzen, Jan; Larsen, Lars Hauer; Kjær, Thomas; Revsbech, Niels-Peter

    1998-01-01

    High-resolution NO3− profiles in freshwater sediment covered with benthic diatoms were obtained with a new microscale NO3− biosensor characterized by absence of interference from chemical species other than NO2− and N2O. Analysis of the microprofiles obtained indicated no nitrification during darkness, high rates of nitrification and a tight coupling between nitrification and denitrification during illumination, and substantial rates of NO3− assimilation during illumination. Nitrification dur...

  10. Transport zonation limits coupled nitrification-denitrification in permeable sediments.

    Science.gov (United States)

    Kessler, Adam J; Glud, Ronnie N; Cardenas, M Bayani; Cook, Perran L M

    2013-01-01

    Measurement of biogeochemical processes in permeable sediments (including the hyporheic zone) is difficult because of complex multidimensional advective transport. This is especially the case for nitrogen cycling, which involves several coupled redox-sensitive reactions. To provide detailed insight into the coupling between ammonification, nitrification and denitrification in stationary sand ripples, we combined the diffusion equilibrium thin layer (DET) gel technique with a computational reactive transport biogeochemical model. The former approach provided high-resolution two-dimensional distributions of NO3(-) and (15)N-N2 gas. The measured two-dimensional profiles correlate with computational model simulations, showing a deep pool of N2 gas forming, and being advected to the surface below ripple peaks. Further isotope pairing calculations on these data indicate that coupled nitrification-denitrification is severely limited in permeable sediments because the flow and transport field limits interaction between oxic and anoxic pore water. The approach allowed for new detailed insight into subsurface denitrification zones in complex permeable sediments. PMID:24224741

  11. Empowering a mesophilic inoculum for thermophilic nitrification: Growth mode and temperature pattern as critical proliferation factors for archaeal ammonia oxidizers.

    Science.gov (United States)

    Courtens, Emilie N P; Vandekerckhove, Tom; Prat, Delphine; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Meerbergen, Ken; Lievens, Bart; Boon, Nico; Vlaeminck, Siegfried E

    2016-04-01

    Cost-efficient biological treatment of warm nitrogenous wastewaters requires the development of thermophilic nitrogen removal processes. Only one thermophilic nitrifying bioreactor was described so far, achieving 200 mg N L(-1) d(-1) after more than 300 days of enrichment from compost samples. From the practical point of view in which existing plants would be upgraded, however, a more time-efficient development strategy based on mesophilic nitrifying sludge is preferred. This study evaluated the adaptive capacities of mesophilic nitrifying sludge for two linear temperature increase patterns (non-oscillating vs. oscillating), two different slopes (0.25 vs. 0.08 °C d(-1)) and two different reactor types (floc vs. biofilm growth). The oscillating temperature pattern (0.25 °C d(-1)) and the moving bed biofilm reactor (0.08 °C d(-1)) could not reach nitrification at temperatures higher than 46 °C. However, nitrification rates up to 800 mg N L(-1) d(-1) and 150 mg N g(-1) volatile suspended solids d(-1) were achieved at a temperature as high as 49 °C by imposing the slowest linear temperature increase to floccular sludge. Microbial community analysis revealed that this successful transition was related with a shift in ammonium oxidizing archaea dominating ammonia oxidizing bacteria, while for nitrite oxidation Nitrospira spp. was constantly more abundant than Nitrobacter spp.. This observation was accompanied with an increase in observed sludge yield and a shift in maximal optimum temperature, determined with ex-situ temperature sensitivity measurements, predicting an upcoming reactor failure at higher temperature. Overall, this study achieved nitrification at 49 °C within 150 days by gradual adaptation of mesophilic sludge, and showed that ex-situ temperature sensitivity screening can be used to monitor and steer the transition process. PMID:26841233

  12. Kinetic evaluation of nitrification performance in an immobilized cell membrane bioreactor.

    Science.gov (United States)

    Güven, D; Ubay Çokgör, E; Sözen, S; Orhon, D

    2016-01-01

    High rate membrane bioreactor (MBR) systems operated at extremely low sludge ages (superfast membrane bioreactors (SFMBRs)) are inefficient to achieve nitrogen removal, due to insufficient retention time for nitrifiers. Moreover, frequent chemical cleaning is required due to high biomass flux. This study aims to satisfy the nitrification in SFMBRs by using sponge as carriers, leading to the extension of the residence time of microorganisms. In order to test the limits of nitrification, bioreactor was run under 52, 5 and 2 days of carrier residence time (CRT), with a hydraulic retention time of 6 h. Different degrees of nitrification were obtained for different CRTs. Sponge immobilized SFMBR operation with short CRT resulted in partial nitrification indicating selective dominancy of ammonia oxidizers. At higher CRT, simultaneous nitrification-denitrification was achieved when accompanying with oxygen limitation. Process kinetics was determined through evaluation of the results by a modeling study. Nitrifier partition in the reactor was also identified by model calibration. PMID:27332835

  13. Mineralization and nitrification patterns at eight northeastern USA forested research sites

    Science.gov (United States)

    Ross, D.S.; Lawrence, G.B.; Fredriksen, G.

    2004-01-01

    Nitrogen transformation rates in eight northeastern US research sites were measured in soil samples taken in the early season of 2000 and the late season of 2001. Net mineralization and nitrification rates were determined on Oa or A horizon samples by two different sampling methods - intact cores and repeated measurements on composite samples taken from around the cores. Net rates in the composite samples (n=30) showed three different temporal patterns: high net nitrification with minimal NH4+ accumulation, high net nitrification and high NH4+ accumulation, and minimal net nitrification and moderate NH4+ accumulation. The 4-week net rates in intact cores were about half that of the rates from the composite samples but were well related (R2 > 0.70). Composite samples from sites that exhibited high net nitrification were incubated with acetylene and net nitrification was completely stopped, suggesting an autotrophic pathway. Gross mineralization and nitrification (2000 only) rates were estimated using the isotope dilution technique. Gross rates of nitrification and consumption in intact cores were relatively low. Gross rates of mineralization and net rates of nitrification were both related to the soil C/N ratio, with higher rates generally occurring in sites containing Acer saccharum as a dominant or co-dominant species. The comparison of methods suggests that all provide a similar hierarchy of potential rates but that the degree of net nitrification is strongly influenced by the degree of sample disturbance. Differences between sites appear to be related to an interaction of soil (C/N) and vegetation (A. saccharum contribution) characteristics. ?? 2003 Elsevier B.V. All rights reserved.

  14. Mechanistic model for interpreting the toxic effects of sulfonamides on nitrification.

    Science.gov (United States)

    Huang, Xiangfeng; Feng, Yi; Hu, Cui; Xiao, Xiaoyu; Yu, Daliang; Zou, Xiaoming

    2016-03-15

    Antibiotics are categorized as pseudopersistent compounds because of their widespread use and continuous emission into the environment. Biological systems such as active sludge and biofilms are still the principal tools used to remove antibiotics in wastewater treatment plants (WWTPs). Consequently, it is important to determine the relationship between toxic effects in biological WWTPs and the structural characteristics of antibiotics. In the present study, toxic effects of 10 sulfonamides (SAs) on nitrification in an active sludge system were studied. The toxicity results (half-effective concentrations, EC50) indicated that the toxicity of sulfadimethoxine (SDM) is approximately 4 times as large as that of sulfadiazine (SD). Based on the toxicity mechanism and the partial least squares regression (PLS) method, an optimum quantitative structure-activity relationship (QSAR) model was developed for the test system. The mechanistic model showed that the pKa, the binding energies between SAs with dihydropteroate synthetase ( [Formula: see text] ) and the binding energies between SAs with ammonia monooxygenase ( [Formula: see text] ) are the key factors affecting the toxic effects of SAs on nitration process in active sludge system, following an order of importance of [Formula: see text] > [Formula: see text] >pKa. PMID:26651069

  15. Effect of nitrification inhibitors (DMPP and 3MP+TZ) on soil nitrous oxide emissions from a sub-tropical vegetable production system in Queensland, Australia

    Science.gov (United States)

    Scheer, Clemens; Deuter, Peter; Firrell, Mary; Rowlings, David; Grace, Peter

    2015-04-01

    The use of nitrification inhibitors, in combination with ammonium based fertilisers, has been promoted recently as an effective method to reduce nitrous oxide (N2O) emissions from fertilised agricultural fields, whilst increasing yield and nitrogen use efficiency. Vegetable cropping systems are often characterised by high inputs of nitrogen fertiliser and consequently elevated emissions of nitrous oxide (N2O) can be expected. However, to date only limited data is available on the use of nitrification inhibitors in sub-tropical vegetable systems. A field experiment investigated the effect of the nitrification inhibitors (DMPP & 3MP+TZ) on N2O emissions and yield from a typical vegetable production system in sub-tropical Australia. Soil N2O fluxes were monitored continuously over an entire year with a fully automated system. Measurements were taken from three subplots for each treatment within a randomized complete blocks design. There was a significant inhibition effect of DMPP and 3MP+TZ on N2O emissions and soil mineral N content directly following the application of the fertiliser over the vegetable cropping phase. However this mitigation was offset by elevated N2O emissions from the inhibitor treatments over the post-harvest fallow period. Cumulative annual N2O emissions amounted to 1.22 kg-N/ha, 1.16 kg-N/ha, 1.50 kg-N/ha and 0.86 kg-N/ha in the conventional fertiliser (CONV), the DMPP treatment, the 3MP+TZ treatment and the zero fertiliser (0N) respectively. Corresponding fertiliser induced emission factors (EFs) were low with only 0.09 - 0.20% of the total applied fertiliser lost as N2O. There was no significant effect of the nitrification inhibitors on yield compared to the CONV treatment for the three vegetable crops (green beans, broccoli, lettuce) grown over the experimental period. This study highlights that N2O emissions from such vegetable cropping system are primarily controlled by post-harvest emissions following the incorporation of vegetable crop

  16. Acceleration of aged-landfill stabilization by combining partial nitrification and leachate recirculation: A field-scale study

    International Nuclear Information System (INIS)

    Highlights: • To solve the drawbacks (NH4+ accumulation) of leachate recirculation, ex-situ SBR was applied. • Produced NO2− was recirculated and denitrified to N2 in landfill with insufficient carbon source. • Despite the inhibition of methanogenesis by DO and nitrate, CH4 fraction eventually increased. - Abstract: Leachate recirculation for rapid landfill stabilization can result in the accumulation of high-strength ammonium. An on-site sequencing batch reactor (SBR) was therefore, applied to oxidize the ammonium to nitrite, which was then recirculated to the landfill for denitrification to nitrogen gas. At relatively higher ammonium levels, nitrite accumulated well in the SBR; the nitrite was denitrified stably in the landfill, despite an insufficient biodegradable carbon source in the leachate. As the leachate was recirculated, the methane and carbon dioxide contents produced from the landfill fluctuated, implying that the organic acids and hydrogen produced in the acid production phase acted as the carbon source for denitrification in the landfill. Leachate recirculation combined with ex-situ partial nitrification of the leachate may enhance the biodegradation process by: (a) removing the nitrogen that is contained with the leachate, and (b) accelerating landfill stabilization, because the biodegradation efficiency of landfill waste is increased by supplying sufficient moisture and its byproducts are used as the carbon source for denitrification. In addition, partial nitrification using an SBR has advantages for complete denitrification in the landfill, since the available carbon source is in short supply in aged landfills

  17. Monitoring the nitrification and identifying the endpoint of ammonium oxidation by using a novel system of titrimetry.

    Science.gov (United States)

    Zhang, Xin; Zhang, Daijun; Lu, Peili; Bai, Cui; Xiao, Pengying

    2011-01-01

    Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry-titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor. PMID:22156129

  18. Removal of Nitrogen and Phosphorus From Reject Water Using Chlorella vulgaris Algae After Partial Nitrification/Anammox Process.

    Science.gov (United States)

    Gutwinski, Piotr; Cema, Grzegorz

    2016-01-01

    Wastewater containing nutrients like ammonia, nitrite, nitrate and phosphates have been identified as the main cause of eutrophication in natural waters. Therefore, a suitable treatment is needed. In classical biological processes, nitrogen and phosphorus removal is expensive, especially due to the lack of biodegradable carbon, thus new methods are investigated. In this paper, the new possibility of nitrogen and phosphorus removal in side stream after the partial nitrification/Anammox process is proposed. Research was carried out in a lab-scale vertical tubular photobioreactor (VTR) fed with real reject water, from dewatering of digested sludge, after partial nitrification/Anammox process from lab-scale sequencing batch reactor (SBR). Nitrogen and phosphorus concentrations were measured every three days. The average nitrogen and phosphorus loads were 0.0503 ± 0.036 g N g(vss)/d and 0.0389 ± 0.013 g P g(vss)/d accordingly. Results have shown that microalgae were able to efficiently remove nitrogen and phosphorus. The average nitrogen removal was 36.46% and phosphorus removal efficiency varied between 93 and 100%. PMID:26803028

  19. Impact of nitrification inhibitor with organic manure and urea on nitrogen dynamics and N2O emission in acid sulphate soil

    Directory of Open Access Journals (Sweden)

    Shordar Mohamed Shamsuzzaman

    2016-03-01

    Full Text Available ABSTRACT The accurate prediction of N transformation is an important requisite for optimizing N use efficiency in cropping systems. An incubation study was conducted to verify the impacts of nitrification inhibitor (NI with organic manure (OM and urea on N dynamics and N2O emission in acid sulphate soil. The conducted experiment was two-level factorial with 4 N sources (N1 = 100% of N from urea, N2 = 75% of N from urea + 25% N from rice straw, N3 = 75% of N from urea + 25% of N from cow dung and N4 = 75% of N from urea + 25% of N from poultry dung and two levels of NI (with and without DCD. The NI (Dicyandiamide - DCD with OM + urea enhanced mineral N contents and it was the highest (255.07 µg∙g-1 for urea with DCD applications. The highest net N-mineralization (213.07 µg∙g-1 was recorded for the application of urea with DCD and net nitrification (16.26 µg∙g-1 was recorded for the application of urea alone, but the highest cumulative N2O emission (5.46 µg∙g-1 was in urea + poultry dung (PD. In addition, DCD most effectively inhibited net nitrification (28.78% and N2O emission (32.40% from cow dung (CD and urea in the tested soils. The combination of DCD with CD and urea was more effective in reducing N2O emissions (43.69%. These results suggest that the DCD with CD and urea may be the most potential combination to reduce nitrification and N2O emission as well as N loss from acid sulphate soil.

  20. Impact of nitrification inhibitor with organic manure and urea on nitrogen dynamics and N2O emission in acid sulphate soil

    Directory of Open Access Journals (Sweden)

    Shordar Mohamed Shamsuzzaman

    2015-01-01

    Full Text Available ABSTRACT The accurate prediction of N transformation is an important requisite for optimizing N use efficiency in cropping systems. An incubation study was conducted to verify the impacts of nitrification inhibitor (NI with organic manure (OM and urea on N dynamics and N2O emission in acid sulphate soil. The conducted experiment was two-level factorial with 4 N sources (N1 = 100% of N from urea, N2 = 75% of N from urea + 25% N from rice straw, N3 = 75% of N from urea + 25% of N from cow dung and N4 = 75% of N from urea + 25% of N from poultry dung and two levels of NI (with and without DCD. The NI (Dicyandiamide - DCD with OM + urea enhanced mineral N contents and it was the highest (255.07 µg∙g-1 for urea with DCD applications. The highest net N-mineralization (213.07 µg∙g-1 was recorded for the application of urea with DCD and net nitrification (16.26 µg∙g-1 was recorded for the application of urea alone, but the highest cumulative N2O emission (5.46 µg∙g-1 was in urea + poultry dung (PD. In addition, DCD most effectively inhibited net nitrification (28.78% and N2O emission (32.40% from cow dung (CD and urea in the tested soils. The combination of DCD with CD and urea was more effective in reducing N2O emissions (43.69%. These results suggest that the DCD with CD and urea may be the most potential combination to reduce nitrification and N2O emission as well as N loss from acid sulphate soil.

  1. Reduction of nitrous oxide emissions from partial nitrification process by using innovative carbon source (mannitol).

    Science.gov (United States)

    Zhang, Xinwen; Wang, Xiaoqing; Zhang, Jian; Huang, Xiaoyu; Wei, Dong; Lan, Wei; Hu, Zhen

    2016-10-01

    The purpose of this study was to evaluate the effect of mannitol as carbon source on nitrogen removal and nitrous oxide (N2O) emission during partial nitrification (PN) process. Laboratory-scale PN sequencing batch reactors (SBRs) were operated with mannitol and sodium acetate as carbon sources, respectively. Results showed that mannitol could remarkably reduce N2O-N emission by 41.03%, without influencing the removal efficiency of NH4(+)-N. However, it has a significant influence on nitrite accumulation ratio (NAR) and TN removal, which were 19.97% and 13.59% lower than that in PN with sodium acetate, respectively. Microbial analysis showed that the introduction of mannitol could increase the abundance of bacteria encoding nosZ genes. In addition, anti-oxidant enzymes (T-SOD, POD and CAT) activities were significantly reduced and the dehydrogenase activity had an obvious increase in mannitol system, indicating that mannitol could alleviate the inhibition of N2O reductase (N2OR) activities caused by high NO2(-)-N concentration. PMID:27423546

  2. Side Effects of Nitrification Inhibitors on Non Target Microbial Processes in Soils

    Directory of Open Access Journals (Sweden)

    Johannes Carl Gottlieb Ottow

    2011-01-01

    Full Text Available Agricultural chemicals have been used extensively in modern agriculture and toxicological studies suggest a great potential for inducing undesirable effects on non target organisms. A model experiment was conducted in order to determine side effects of three nitrification inhibitors (NIs, 3,4dimethylpyrazolephosphate = DMPP, 4-Chlor-methylpyrazole phosphate = ClMPP and dicyandiamide = DCD on non target microbial processes in soils. Side effects and dose response curve of three NIs were quantified under laboratory conditions using silty clay, loam and a sandy soils. Dehydrogenase, dimethylsulfoxide reductase as well as nitrogenase activity (NA and potential denitrification capacity were measured as common and specific non target microbial processes. The influence of 5-1000 times the base concentration, dose response curves were examined, and no observable effect level = NOEL, as well as effective dose ED10 and ED50 (10% and 50% inhibition were calculated. The NOEL for microbial non target processes were about 30–70 times higher than base concentration in all investigated soils. The potential denitrification capacity revealed to be the most sensitive parameter. ClMPP exhibited the strongest influence on the non target microbial processes in the three soils. The NOEL, ED10 and ED50 values were higher in clay than in loamy or sandy soil. The NIs was the most effective in sandy soils.

  3. Experimental study on the inhibition of biological reduction of Fe(III)EDTA in NOx absorption solution*

    OpenAIRE

    Li, Wei; Wu, Cheng-zhi; Zhang, Shi-han; Shi, Yao; Lei, Le-cheng

    2005-01-01

    Scrubbing of NOx from the gas phase with Fe(II)EDTA has been shown to be highly effective. A new biological method can be used to convert NO to N2 and regenerate the chelating agent Fe(II)EDTA for continuous NO absorption. The core of this biological regeneration is how to effectively simultaneous reduce Fe(III)EDTA and Fe(II)EDTA-NO, two mainly products in the ferrous chelate absorption solution. The biological reduction rate of Fe(III)EDTA plays a main role for the NOx removal efficiency. I...

  4. Inhibition of bacterial ammonia oxidation by organohydrazines in soil microcosms

    Directory of Open Access Journals (Sweden)

    Yucheng eWu

    2012-01-01

    Full Text Available Hydroxylamine oxidation by hydroxylamine oxidoreductase (HAO is a key step for energy-yielding in support of the growth of ammonia-oxidizing bacteria (AOB. Organohydrazines have been shown to inactivate HAO from Nitrosomonas europaea, and may serve as selective inhibitors to differentiate bacterial from archaeal ammonia oxidation due to the absence of bacterial HAO gene homologue in known ammonia-oxidizing archaea (AOA. In this study, the effects of three organohydrazines on activity, abundance and composition of AOB and AOA were evaluated in soil microcosms. The results indicate that phenylhydrazine and methylhydrazine at the concentration of 100 mol per gram dry weight soil completely suppressed the activity of soil nitrification. DGGE fingerprinting and sequencing analysis of bacterial ammonia monooxygenase subunit A gene (amoA clearly demonstrated that nitrification activity change is well paralleled with the growth of Nitrosomonas europaea-like AOB in soil microcosms. No significant correlation between AOA community structure and nitrification activity was observed among all treatments during the incubation period, although incomplete inhibition of nitrification activity occurred in 2-hydroxyethylhydrazine-amended soil microcosms. These findings show that the HAO-targeted organohydrazines can effectively inhibit bacterial nitrification in soil, and the mechanism of organohydrazine affecting AOA remains unclear.

  5. Simultaneous nitrification-denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Yousef, E-mail: you.rahimi@gmail.com [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Torabian, Ali, E-mail: atorabi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Mehrdadi, Naser, E-mail: mehrdadi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Shahmoradi, Behzad, E-mail: bshahmorady@gmail.com [Department of Environmental Science, University of Mysore, MGM-06 Mysore (India)

    2011-01-30

    Research highlights: {yields} Sludge production in FSBR reactor is 20-30% less than SBR reactor. {yields} FSBR reactor showed more nutrient removal rate than SBR reactor. {yields} FSBR reactor showed less VSS/TSS ratio than SBR reactor. - Abstract: Biological nutrient removal (BNR) was investigated in a fixed bed sequencing batch reactor (FBSBR) in which instead of activated sludge polypropylene carriers were used. The FBSBR performance on carbon and nitrogen removal at different loading rates was significant. COD, TN, and phosphorus removal efficiencies were at range of 90-96%, 60-88%, and 76-90% respectively while these values at SBR reactor were 85-95%, 38-60%, and 20-79% respectively. These results show that the simultaneous nitrification-denitrification (SND) is significantly higher than conventional SBR reactor. The higher total phosphorus (TP) removal in FBSBR correlates with oxygen gradient in biofilm layer. The influence of fixed media on biomass production yield was assessed by monitoring the MLSS concentrations versus COD removal for both reactors and results revealed that the sludge production yield (Y{sub obs}) is significantly less in FBSBR reactors compared with SBR reactor. The FBSBR was more efficient in SND and phosphorus removal. Moreover, it produced less excess sludge but higher in nutrient content and stabilization ratio (less VSS/TSS ratio).

  6. Simultaneous nitrification-denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)

    International Nuclear Information System (INIS)

    Research highlights: → Sludge production in FSBR reactor is 20-30% less than SBR reactor. → FSBR reactor showed more nutrient removal rate than SBR reactor. → FSBR reactor showed less VSS/TSS ratio than SBR reactor. - Abstract: Biological nutrient removal (BNR) was investigated in a fixed bed sequencing batch reactor (FBSBR) in which instead of activated sludge polypropylene carriers were used. The FBSBR performance on carbon and nitrogen removal at different loading rates was significant. COD, TN, and phosphorus removal efficiencies were at range of 90-96%, 60-88%, and 76-90% respectively while these values at SBR reactor were 85-95%, 38-60%, and 20-79% respectively. These results show that the simultaneous nitrification-denitrification (SND) is significantly higher than conventional SBR reactor. The higher total phosphorus (TP) removal in FBSBR correlates with oxygen gradient in biofilm layer. The influence of fixed media on biomass production yield was assessed by monitoring the MLSS concentrations versus COD removal for both reactors and results revealed that the sludge production yield (Yobs) is significantly less in FBSBR reactors compared with SBR reactor. The FBSBR was more efficient in SND and phosphorus removal. Moreover, it produced less excess sludge but higher in nutrient content and stabilization ratio (less VSS/TSS ratio).

  7. Efficient COD removal and nitrification in an upflow microaerobic sludge blanket reactor for domestic wastewater.

    Science.gov (United States)

    Zheng, Shaokui; Cui, Cancan

    2012-03-01

    The treatment performance of an upflow microaerobic sludge blanket reactor (UMSB) for synthetic domestic wastewater was investigated at two dissolved oxygen (DO) levels, 0.3-0.5 and 0.7-0.9 mg l(-1), focusing on nitrification performance. The higher DO level induced complete nitrification of ammonia nitrogen (NH(3)-N), achieving chemical oxygen demand and NH(3)-N removals of 97 and 92%, respectively. There were consistently significantly higher nitrate nitrogen (NO(3)-N) and nitrite nitrogen (NO(2)-N) levels in the effluent, with ~66% of newly-produced oxidised nitrogen as NO(2)-N. Despite the high nitrification efficiency, only about 23% of the removed NH(3)-N amount from the influent was ultimately transformed into oxidised nitrogen due to the simultaneous nitrification-denitrification. Sludge blanket development and granulation occurred simultaneously in the UMSB. PMID:22105554

  8. Green and controllable metal-free nitrification and nitration of arylboronic acids

    Institute of Scientific and Technical Information of China (English)

    Shuai Wang; Chun Chun Shu; Tao Wang; Jian Yu; Guo Bing Yan

    2012-01-01

    A novel and green nitrating reagent has been developed for the nitrification and nitration of arylboronic acids,which can be controlled by the reaction conditions.The process provides an attractive alternative to the traditional nitration protocols.

  9. Biofilm Community Dynamics in Bench-Scale Annular Reactors Simulating Arrestment of Chloraminated Drinking Water Nitrification

    Science.gov (United States)

    Annular reactors (ARs) were used to study biofilm community succession and provide an ecological insight during nitrification arrestment through simultaneously increasing monochloramine (NH2Cl) and chlorine to nitrogen mass ratios, resulting in four operational periods (I to IV)....

  10. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    Science.gov (United States)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

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

    NARCIS (Netherlands)

    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

  12. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Science.gov (United States)

    Veuger, B.; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J. S.; Middelburg, J. J.

    2013-03-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon) in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate) in combination with compound-specific stable isotope (13C) analysis of bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41-221 nmol N L-1 h-1). Ammonium assimilation was always substantially lower than nitrification - with nitrification on average contributing 89% (range 73-97%) to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27-95 %). The inhibitor-sensitive 13C-PLFA (phospholipid-derived fatty acid) pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance (16S rRNA and amoA (ammonia monooxygenase)). These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance measurements only, in order to

  13. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Directory of Open Access Journals (Sweden)

    B. Veuger

    2013-03-01

    Full Text Available Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate in combination with compound-specific stable isotope (13C analysis of bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41–221 nmol N L−1 h−1. Ammonium assimilation was always substantially lower than nitrification – with nitrification on average contributing 89% (range 73–97% to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27–95 %. The inhibitor-sensitive 13C-PLFA (phospholipid-derived fatty acid pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance (16S rRNA and amoA (ammonia monooxygenase. These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance

  14. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    Directory of Open Access Journals (Sweden)

    B. Veuger

    2012-11-01

    Full Text Available Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate in combination with compound-specific stable isotope (13C analysis of bacterial- and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41–221 nmol N l−1h−1. Ammonium assimilation was always substantially lower than nitrification with nitrification on average contributing 89% (range 73–97% to total ammonium consumption.

    13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27–95%. The inhibitor-sensitive 13C-PLFA pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. Cell-specific 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance. These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance

  15. Effect of nitrification on phosphorus dissolving in a piggery effluent treated by a sequencing batch reactor

    OpenAIRE

    Daumer, M.L.; Béline, F.; Guiziou, F.; Spérandio, M

    2007-01-01

    The effect of the nitrification on dissolved phosphorus during the treatment of piggery wastewater by a modified sequencing batch reactor has been observed in a previous study. The high solid mineral phosphorus content in the piggery wastewater and the chemical mechanism induced by the fall in pH during the nitrification were proposed to explain this effect. In this work, trials using modified sequencing batch reactors were performed to study the influence of the amount of nitrified nitrogen ...

  16. Feasibility of simultaneous nitrification and denitrification in a pilot-scale airlift-loop reactor

    OpenAIRE

    X. Hao; Nieuwstad, T.J.

    1993-01-01

    Airlift-loop reactors have become competitive in treating municipal wastewater. Many studies have verified that high COD conversion efficiencies can be reached. When simultaneous nitrification and denitrification could be realised to the same degree as is possible in low loaded conventional activated sludge processes, their application would be more interesting. In theory nitrification and denitrification are simultaneously possible in an airlift-loop reactor. Based on qualitative assumptions...

  17. Spatial patterns of soil nitrification and nitrate export from forested headwaters in the northeastern United States

    Science.gov (United States)

    Ross, D.S.; Shanley, J.B.; Campbell, J.L.; Lawrence, G.B.; Bailey, S.W.; Likens, G.E.; Wemple, B.C.; Fredriksen, G.; Jamison, A.E.

    2012-01-01

    Nitrogen export from small forested watersheds is known to be affected by N deposition but with high regional variability. We studied 10 headwater catchments in the northeastern United States across a gradient of N deposition (5.4 - 9.4 kg ha -1 yr -1) to determine if soil nitrification rates could explain differences in stream water NO 3 - export. Average annual export of two years (October 2002 through September 2004) varied from 0.1 kg NO 3 --N ha -1 yr -1 at Cone Pond watershed in New Hampshire to 5.1 kg ha -1 yr -1 at Buck Creek South in the western Adirondack Mountains of New York. Potential net nitrification rates and relative nitrification (fraction of inorganic N as NO 3 -) were measured in Oa or A soil horizons at 21-130 sampling points throughout each watershed. Stream NO 3 - export was positively related to nitrification rates (r 2 = 0.34, p = 0.04) and the relative nitrification (r 2 = 0.37, p = 0.04). These relationships were much improved by restricting consideration to the 6 watersheds with a higher number of rate measurements (59-130) taken in transects parallel to the streams (r 2 of 0.84 and 0.70 for the nitrification rate and relative nitrification, respectively). Potential nitrification rates were also a better predictor of NO 3 - export when data were limited to either the 6 sampling points closest to the watershed outlet (r 2 = 0.75) or sampling points <250 m from the watershed outlet (r 2 = 0.68). The basal area of conifer species at the sampling plots was negatively related to NO 3 - export. These spatial relationships found here suggest a strong influence of near-stream and near-watershed-outlet soils on measured stream NO 3 - export. Copyright 2012 by the American Geophysical Union.

  18. Nitrification in marine ecosystems [Translation from: Rapp.Naturvardsverket SNVPM No.1213, 157-166, 1980

    OpenAIRE

    Enoksson, V.

    1986-01-01

    The nitrification in the ocean is influenced by several environmental factors and the importance of these is more or less known. There are very likely many more to be discovered in the study of the interaction of nitrification bacteria and other micro-organisms in the ocean. Some of the factors to be considered will briefly be dealt with in this paper. Then the authors give the results of an incubation experiment in the Baltic Sea and from a detailed study in Gullmarn.

  19. MODELING OF THE NITRIFICATION PROCESS IN A SOIL IN CĂLĂRAŞI COUNTY

    OpenAIRE

    Cecilia NEAGU

    2015-01-01

    Quantifying the best possible the nitrification of nitrogen in the soil remains an important issue for the sustainable agriculture and for the environmental protection. The aim of the study was to evaluate in the laboratory the influence of some factors: temperature, humidity and amount of manure incorporated in the process of nitrification in a soil mainly in Călăraşi county, on a cambic chernozem. The results of the laboratory analyses were statistically processed by the analysis of variati...

  20. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    OpenAIRE

    B. Veuger; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J.S.; Middelburg, J. J.

    2013-01-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC in the presence and absen...

  1. Effect of ciliates on nitrification and nitrifying bacteria in Baltic Sea sediments

    OpenAIRE

    Prast, M.; Bischof, Adrian A.; Waller, Uwe; Amann, R.; Berninger, U.-G.

    2007-01-01

    Nitrification in aquatic sediments is catalyzed by bacteria. While many autecological studies on these bacteria have been published, few have regarded them as part of the benthic microbial food web. Ciliates are important as grazers on bacteria, but also for remineralization of organic matter. We tested the hypothesis that ciliates can affect nitrification. Experiments with Baltic Sea sediments in laboratory flumes, with or without the addition of cultured ciliates, were conducted. We found i...

  2. Links between Ammonia Oxidizer Community Structure, Abundance, and Nitrification Potential in Acidic Soils ▿ †

    OpenAIRE

    Yao, Huaiying; Gao, Yangmei; Nicol, Graeme W.; Campbell, Colin D.; Prosser, James I.; Zhang, Limei; Han, Wenyan; Singh, Brajesh K.

    2011-01-01

    Ammonia oxidation is the first and rate-limiting step of nitrification and is performed by both ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the environmental drivers controlling the abundance, composition, and activity of AOA and AOB communities are not well characterized, and the relative importance of these two groups in soil nitrification is still debated. Chinese tea orchard soils provide an excellent system for investigating the long-term effects of low pH and nitrogen f...

  3. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil

    Science.gov (United States)

    Banning, Natasha C.; Maccarone, Linda D.; Fisk, Louise M.; Murphy, Daniel V.

    2015-06-01

    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10 cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

  4. Operating a pilot-scale nitrification/distillation plant for complete nutrient recovery from urine.

    Science.gov (United States)

    Fumasoli, Alexandra; Etter, Bastian; Sterkele, Bettina; Morgenroth, Eberhard; Udert, Kai M

    2016-01-01

    Source-separated urine contains most of the excreted nutrients, which can be recovered by using nitrification to stabilize the urine before concentrating the nutrient solution with distillation. The aim of this study was to test this process combination at pilot scale. The nitrification process was efficient in a moving bed biofilm reactor with maximal rates of 930 mg N L(-1) d(-1). Rates decreased to 120 mg N L(-1) d(-1) after switching to more concentrated urine. At high nitrification rates (640 mg N L(-1) d(-1)) and low total ammonia concentrations (1,790 mg NH4-N L(-1) in influent) distillation caused the main primary energy demand of 71 W cap(-1) (nitrification: 13 W cap(-1)) assuming a nitrogen production of 8.8 g N cap(-1) d(-1). Possible process failures include the accumulation of the nitrification intermediate nitrite and the selection of acid-tolerant ammonia-oxidizing bacteria. Especially during reactor start-up, the process must therefore be carefully supervised. The concentrate produced by the nitrification/distillation process is low in heavy metals, but high in nutrients, suggesting a good suitability as an integral fertilizer. PMID:26744953

  5. The biological role of fetuin-B : inhibition of zona pellucida hardening and preservation of female fertility in mice

    OpenAIRE

    Dietzel, Eileen

    2014-01-01

    Fetuin-B is a hepatic plasma protein, well conserved in mammals. Fetuin-B associates with the extracellular matrix and was shown to surround the oocytes during development and maturation. A layer of extracellular matrix, the Zona pellucida (ZP), surrounds mammalian oocytes. Before fertilization sperm are able to penetrate the ZP. After fertilization proteases are released by the oocyte, leading to structural ZP modification and inhibition of further sperm binding. This process is called ferti...

  6. Serratia secondary metabolite prodigiosin inhibit Pseudomonas aeruginosa biofilm development by producing reactive oxygen species that damage biological molecules.

    Directory of Open Access Journals (Sweden)

    Onder eKimyon

    2016-06-01

    Full Text Available Prodigiosin is a heterocyclic bacterial secondary metabolite belonging to the class of tripyrrole compounds, synthesized by various types of bacteria including Serratia species. Prodigiosin has been the subject of intense research over the last decade for its ability to induce apoptosis in several cancer cell lines. Reports suggest that prodigiosin promotes oxidative damage to double-stranded DNA (dsDNA in the presence of copper ions and consequently leads to inhibition of cell-cycle progression and cell death. However, prodigiosin has not been previously implicated in biofilm inhibition. In this study, the link between prodigiosin and biofilm inhibition through the production of redox active metabolites is presented. Our study showed that prodigiosin (500 µM (extracted from Serratia marcescens culture and a prodigiosin/copper(II (100 µM each complex have strong RNA and dsDNA cleaving properties while they have no pronounced effect on protein. Results support a role for oxidative damage to biomolecules by H2O2 and hydroxyl radical generation. Further, it was demonstrated that reactive oxygen species scavengers significantly reduced the DNA and RNA cleaving property of prodigiosin. P. aeruginosa cell surface hydrophobicity and biofilm integrity were significantly altered due to the cleavage of nucleic acids by prodigiosin or the prodigiosin/copper(II complex. In addition, prodigiosin also facilitated the bactericidal activity. The ability of prodigiosin to cause nucleic acid degradation offers novel opportunities to interfere with extracellular DNA dependent bacterial biofilms.

  7. Effects of a clearcut on the net rates of nitrification and N mineralization in a northern hardwood forest, Catskill Mountains, New York, USA

    Science.gov (United States)

    Burns, Douglas A.; Murdoch, Peter S.

    2005-01-01

    insufficient to measurably affect the net rates of N mineralization and nitrification in the absence of plant uptake. Soil acidification resulting from the harvest may have acted in part to inhibit the rates of these processes. ?? Springer 2005.

  8. 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

  9. Impact of water boundary layer diffusion on the nitrification rate of submerged biofilter elements from a recirculating aquaculture system

    DEFF Research Database (Denmark)

    Prehn, Jonas; Waul, Christopher Kevin; Pedersen, Lars-Flemming;

    2012-01-01

    Total ammonia nitrogen (TAN) removal by microbial nitrification is an essential process in recirculating aquaculture systems (RAS). In order to protect the aquatic environment and fish health, it is important to be able to predict the nitrification rates in RAS’s. The aim of this study was to...... determine the impact of hydraulic film diffusion on the nitrification rate in a submerged biofilter. Using an experimental batch reactor setup with recirculation, active nitrifying biofilter units from a RAS were exposed to a range of hydraulic flow velocities. Corresponding nitrification rates were...... measured following ammonium chloride, NH4Cl, spikes and the impact of hydraulic film diffusion was quantified. The nitrification performance of the tested biofilter could be significantly increased by increasing the hydraulic flow velocity in the filter. Area based first order nitrification rate constants...

  10. Archaeal Ammonia Oxidizers Dominate in Numbers, but Bacteria Drive Gross Nitrification in N-amended Grassland Soil

    OpenAIRE

    Sterngren, Anna E.; Hallin, Sara; Bengtson, Per

    2015-01-01

    Both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) play an important role in nitrification in terrestrial environments. Most often AOA outnumber AOB, but the relative contribution of AOA and AOB to nitrification rates remains unclear. The aim of this experiment was to test the hypotheses that high nitrogen availability would favor AOB and result in high gross nitrification rates, while high carbon availability would result in low nitrogen concentrations that favor the a...

  11. Nitrification resilience and community dynamics of ammonia-oxidizing bacteria with respect to ammonia loading shock in a nitrification reactor treating steel wastewater.

    Science.gov (United States)

    Cho, Kyungjin; Shin, Seung Gu; Lee, Joonyeob; Koo, Taewoan; Kim, Woong; Hwang, Seokhwan

    2016-08-01

    The aim of this study was to investigate the nitrification resilience pattern and examine the key ammonia-oxidizing bacteria (AOB) with respect to ammonia loading shocks (ALSs) in a nitrification bioreactor treating steel wastewater. The perturbation experiments were conducted in a 4-L bioreactor operated in continuous mode with a hydraulic retention time of 10 d. Three sequential ALSs were given to the bioreactor (120, 180 and 180 mg total ammonia nitrogen (TAN)/L. When the first shock was given, the nitrification process completely recovered after 14 d of further operation. However, the resilience duration was significantly reduced to ∼1 d after the second and third ALSs. In the bioreactor, Nitrosomonas aestuarii dominated the other AOB species, Nitrosomonas europaea and N. nitrosa, throughout the process. In addition, the population of N. aestuarii increased with ammonia utilization following each ALS; i.e., this species responded to acute ammonia overloadings by contributing to ammonia oxidation. This finding suggests that N. aestuarii could be exploited to achieve stable nitrification in industrial wastewaters that contain high concentrations of ammonia. PMID:26896313

  12. Nitrification and its oxygen consumption along the turbid Changjiang River plume

    Directory of Open Access Journals (Sweden)

    S. S.-Y. Hsiao

    2013-05-01

    Full Text Available Nitrification rates of bulk water (NRb and particle free (NRpf, particle > 3 μm eliminated were determined along the Changjiang River plume in August 2011 by nitrogen isotope tracer technique. Dissolved oxygen (DO, community respiration rate (CR, nutrients, dissolved organic nitrogen, total suspended matter (TSM, particulate organic carbon/nitrogen (POC/PON, acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial amoA abundance on size-fractioned particle (> 3 μm and 0.22–3 μm were measured. The NRb ranged from undetectable up to 4.6 μmol L−1 d−1 peaking at salinity of ~ 29. NRb values were positively correlated with ammonia concentration suggesting the importance of substrate in nitrification. In river mouth and inner plume, NRb was much higher than NRpf indicating nitrifying bacteria is mainly particle-associated, which was supported by amoA gene abundance and regression analysis of TSM and NRb. The estimated oxygen demand of nitrification accounted for 0.4% to 317% of CR. The nitrification oxygen demand is much higher than Redfield model's estimation (23% indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg−1. The excess nitrification oxygen demand showed tendency to occur at lower DO samples accompanying with higher acid-leachable Fe/Mn, which implied reactive Fe3+/Mn4+ may play a role as oxidant in nitrification process. Stoichiometric calculation suggested reactive Fe on particles was even 10-fold the oxidant demand for complete ammonia oxidation along all areas of the plume. The involvement of reactive iron and manganese in nitrification process in oxygenated water further complicated the nitrogen cycling in turbid river plume.

  13. Acceleration of aged-landfill stabilization by combining partial nitrification and leachate recirculation: A field-scale study

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jinwook [R& D Center, Samsung Engineering Co., Ltd., 415-10 Woncheon-dong, Youngtong-gu, Suwon, Gyeonggi-do 443-823 (Korea, Republic of); Kim, Seungjin; Baek, Seungcheon [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of); Lee, Nam-Hoon [Department of Environmental & Energy Engineering, Anyang University, 22 Samdeok-ro, 37 Beon-gil, Manan-gu, Anyang, Gyeonggi-do 430-714 (Korea, Republic of); Park, Seongjun; Lee, Junghun; Lee, Heechang [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of); Bae, Wookeun, E-mail: wkbae@hanyang.ac.kr [Department of Civil and Environmental Engineering, Hanyang University, Sa 3-dong, Sangnok-gu, Ansan, Gyeonggi-do 426-791 (Korea, Republic of)

    2015-03-21

    Highlights: • To solve the drawbacks (NH{sub 4}{sup +} accumulation) of leachate recirculation, ex-situ SBR was applied. • Produced NO{sub 2}{sup −} was recirculated and denitrified to N{sub 2} in landfill with insufficient carbon source. • Despite the inhibition of methanogenesis by DO and nitrate, CH{sub 4} fraction eventually increased. - Abstract: Leachate recirculation for rapid landfill stabilization can result in the accumulation of high-strength ammonium. An on-site sequencing batch reactor (SBR) was therefore, applied to oxidize the ammonium to nitrite, which was then recirculated to the landfill for denitrification to nitrogen gas. At relatively higher ammonium levels, nitrite accumulated well in the SBR; the nitrite was denitrified stably in the landfill, despite an insufficient biodegradable carbon source in the leachate. As the leachate was recirculated, the methane and carbon dioxide contents produced from the landfill fluctuated, implying that the organic acids and hydrogen produced in the acid production phase acted as the carbon source for denitrification in the landfill. Leachate recirculation combined with ex-situ partial nitrification of the leachate may enhance the biodegradation process by: (a) removing the nitrogen that is contained with the leachate, and (b) accelerating landfill stabilization, because the biodegradation efficiency of landfill waste is increased by supplying sufficient moisture and its byproducts are used as the carbon source for denitrification. In addition, partial nitrification using an SBR has advantages for complete denitrification in the landfill, since the available carbon source is in short supply in aged landfills.

  14. cGMP-phosphodiesterase inhibition enhances photic responses and synchronization of the biological circadian clock in rodents.

    Directory of Open Access Journals (Sweden)

    Santiago A Plano

    Full Text Available The master circadian clock in mammals is located in the hypothalamic suprachiasmatic nuclei (SCN and is synchronized by several environmental stimuli, mainly the light-dark (LD cycle. Light pulses in the late subjective night induce phase advances in locomotor circadian rhythms and the expression of clock genes (such as Per1-2. The mechanism responsible for light-induced phase advances involves the activation of guanylyl cyclase (GC, cGMP and its related protein kinase (PKG. Pharmacological manipulation of cGMP by phosphodiesterase (PDE inhibition (e.g., sildenafil increases low-intensity light-induced circadian responses, which could reflect the ability of the cGMP-dependent pathway to directly affect the photic sensitivity of the master circadian clock within the SCN. Indeed, sildenafil is also able to increase the phase-shifting effect of saturating (1200 lux light pulses leading to phase advances of about 9 hours, as well as in C57 a mouse strain that shows reduced phase advances. In addition, sildenafil was effective in both male and female hamsters, as well as after oral administration. Other PDE inhibitors (such as vardenafil and tadalafil also increased light-induced phase advances of locomotor activity rhythms and accelerated reentrainment after a phase advance in the LD cycle. Pharmacological inhibition of the main downstream target of cGMP, PKG, blocked light-induced expression of Per1. Our results indicate that the cGMP-dependent pathway can directly modulate the light-induced expression of clock-genes within the SCN and the magnitude of light-induced phase advances of overt rhythms, and provide promising tools to design treatments for human circadian disruptions.

  15. Regulation and role of epiphytic nitrification and denitrification in macrophyte-dominated systems

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Peder G.

    2000-02-01

    This thesis examines mechanisms regulating bacterial nitrification and denitrification in attached microbial communities on surfaces of aquatic macrophytes. It also evaluates the role of epiphytic nitrification and denitrification for the nitrogen turnover in macrophyte-dominated nutrient-rich freshwater. Epiphytic nitrification is promoted in light and epiphytic denitrification occurs mainly in dark, because the metabolic activity of the aquatic macrophyte and its epiphytes induce in light high and in dark low oxygen concentrations in epiphytic communities. Epiphytic nitrification and denitrification are also affected by the physical and chemical characteristics of the aquatic macrophyte. The spatial distribution of nitrification in emergent macrophyte wetlands is related to the species composition of the emergent vegetation, possibly because of a macrophyte species-related release of organic nitrification inhibitors. Contrasting to nitrifying bacteria, which are lithotrophic, denitrifying bacteria use organic substances as an energy source and are therefore stimulated by the release of organic matter from aquatic macrophytes. Epiphytic communities support more denitrification in nutrient-rich than in nutrient-poor environments. In lakes and ponds, epiphytic denitrification is higher at sheltered locations than at locations exposed to wind-induced water movements or currents. In flowing water, epiphytic denitrification occurs mainly at low oxygen concentrations in the surrounding water. However, because aquatic macrophytes impede water flow and induce low oxygen concentrations in dark, epiphytic denitrification can be present within dense vegetation despite of high oxygen concentrations in the surrounding water. Epiphytic nitrification is almost unaffected by flow conditions, and can occur both in light and in dark. In shallow-water systems such as treatment wetlands, aquatic macrophytes often provide most of the accessible surface area for attached nitrifying and

  16. Potential Nitrification and Nitrogen Mineral of Soil in Coffee Agroforestry System with Various Shading Trees

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    Purwanto .

    2007-05-01

    Full Text Available The role of shading trees in coffee farms has been well understood to establish suitable condition for the growth of coffee trees, on the other hand their role in nitrogen cycle in coffee farming is not yet well understood. The objectives of this study are to investigate the influence of various legume shading trees on the concentration of soil mineral N (N-NH4 + and N-NO3-, potential nitrification and to study the controlling factors of nitrification under field conditions. This field explorative research was carried out in Sumberjaya, West Lampung. Twelve observation plots covered four land use systems (LUS, i.e. 1 Coffee agroforestry with Gliricidiasepium as shade trees; 2 Coffee agroforestry with Gliricidiaas shade trees and Arachis pintoias cover crops; 3Coffee agroforestry with Paraserianthes falcataria as shade trees; and 4 Mixed/multistrata coffee agroforestry with Gliricidiaand other fruit crops as shade trees. Measurements of soil mineral-N concentration were carried out every three weeks for three months. Results showed that shade tree species in coffee agroforestry significantly affected concentrations of soil NH4 +, NO3- and potential nitrification. Mixed coffee agroforestry had the highest NH4+/N-mineral ratio (7.16% and the lowest potential nitrification (0.13 mg NO2-kg-1 hour -1 compared to other coffee agroforestry systems using single species of leguminous shade trees. Ratio of NH4 + /N-mineral increased 0.8—21% while potential nitrification decreased 55—79% in mixed coffee agroforestry compared to coffee agroforestry with Gliricidia or P. falcatariaas shade trees. Coffee agroforestry with P. falcatariaas shade trees had potential nitrification 53% lower and ratio of NH4 + /N-mineral concentration 20% higher than that with Gliricidia. Coffee agroforestry with P. falcataria as shade trees also had organic C content 17% higher, total N 40% higher, available P 112% higher than that with Gliricidia. The presence of A. pintoiin

  17. Use of 15N in nitrification inhibitor studies with special reference to indigenous materials

    International Nuclear Information System (INIS)

    Non-edible oil seed cakes and their constituents have been advantageously used for increasing the efficiency of fertilizer nitrogen (N) for crop production. The beneficial effects of these materials have been attributed to retardation of nitrification, which lessen the loss of N associated with nitrification by leaching and denitrification in situations where these losses are high. However, it is possible that some of the effects of these materials could be due to immobilization-remineralization of N particularly when the carbonaceous materials are added with fertilizers at high rates. A methodology involving the use of 15N-labelled fertilizers is advanced to sort out whether the beneficial effects of non-edible oil seed cakes and other materials are due to retardation of nitrification and or immobilization-remineralization of fertilizer N. Using the proposed technique it would be possible to make realistic evaluation of the wealth of indigenous products as nitrification inhibitors. Following the proposed approach it would also be possible to widen the scope and depth of research in this area for ultimately better exploitation of indigenous materials as nitrification inhibitors. (author). 18 refs

  18. Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor

    International Nuclear Information System (INIS)

    Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl-/L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions.

  19. [Heterotrophic Nitrification and Aerobic Denitrification of the Hypothermia Aerobic Denitrification Bacterium: Arthrobacter arilaitensis].

    Science.gov (United States)

    He, Teng-xia; Ni, Jiu-pai; Li, Zhen-lun; Sun, Quan; Ye Qing; Xu, Yi

    2016-03-15

    High concentrations of ammonium, nitrate and nitrite nitrogen were employed to clarify the abilities of heterotrophic nitrification and aerobic denitrification of Arthrobacter arilaitensis strain Y-10. Meanwhile, by means of inoculating the strain suspension into the mixed ammonium and nitrate, ammonium and nitrite nitrogen simulated wastewater, we studied the simultaneous nitrification and denitrification ability of Arthrobacter arilaitensis strain Y-10. In addition, cell optical density was assayed in each nitrogen removal process to analyze the relationship of cell growth and nitrogen removal efficiency. The results showed that the hypothermia denitrification strain Arthrobacter arilaitensis Y-10 exhibited high nitrogen removal efficiency during heterotrophic nitrification and aerobic denitrification. The ammonium, nitrate and nitrite removal rates were 65.0%, 100% and 61.2% respectively when strain Y-10 was cultivated for 4 d at 15°C with initial ammonium, nitrate and nitrite nitrogen concentrations of 208.43 mg · L⁻¹, 201.16 mg · L⁻¹ and 194.33 mg · L⁻¹ and initial pH of 7.2. Nitrite nitrogen could only be accumulated in the medium containing nitrate nitrogen during heterotrophic nitrification and aerobic denitrification process. Additionally, the ammonium nitrogen was mainly removed in the inorganic nitrogen mixed synthetic wastewater. In short, Arthrobacter arilaitensis Y-10 could conduct nitrification and denitrification effectively under aerobic condition and the ammonium nitrogen removal rate was more than 80.0% in the inorganic nitrogen mixed synthetic wastewater. PMID:27337904

  20. ANALYSIS OF TRICKLE BED AND PACKED BUBBLE COLUMN BIOREACTORS FOR COMBINED CARBON OXIDATION AND NITRIFICATION

    Directory of Open Access Journals (Sweden)

    Iliuta I.

    2002-01-01

    Full Text Available Biological removal of nitrogen and carbon by combined nitrification-oxidation in gas-liquid trickle-bed reactors (TBRs and packed bubble columns (PBCs was analyzed theoretically using a transient two-dimensional model. The model describes TBR and PBC performances at steady state as well as their transient response to a pulse or step increase in inlet methanol and NH4+-nitrogen concentrations. The hydrodynamic parameters were determined from residence time distribution measurements, using an imperfect pulse method for time-domain analysis of nonideal pulse tracer response. A transient diffusion model of the tracer in the porous particle coupled with the piston-dispersion-exchange model was used to interpret the residence time distribution curves obtained. Gas-liquid mass transfer parameters were determined by a stationary method based on the least-squares fit of the calculated concentration profiles in gas phase to the experimental values. Analysis of steady-state performances showed that under like operating conditions, the TBR outperforms the PBC in terms of conversions. A pulse change in the inlet methanol or NH4+-nitrogen concentration causes a negligible transient change in the outlet methanol concentration and a negligible or high transient change in the outlet NH4+-nitrogen concentration. A step change in the inlet methanol concentration causes the negligible transient change in the methanol outlet concentration and a relatively important transient change in the NH4+-nitrogen outlet concentration. A step increase in the NH4+-nitrogen inlet concentration induces a drastic transient change in the NH4+-nitrogen outlet concentration but a negligible transient change in the methanol outlet concentration.

  1. [Effects of salinity on N2O production during nitrification using aerobic granular sludge].

    Science.gov (United States)

    Wang, Shan-Shan; iang, Hong; Gao, Da-Wen

    2014-11-01

    An aerobic SBR biological wastewater treatment system was adopted to measure the N2O production and nitrogen removal using aerobic granular sludge nitrification process under 0, 5, 10 g x L(-1) salinity conditions. The results showed that the N2O production increased with the increase of salinity concentration. At three salinity levels (0, 5, 10 g x L(-1)), the dissolved N2O production was 1.21, 8.99, 24.81 mg x m(-3), respectively, and the released N2O was 0.95, 3.46, 16.45 mg x m(-3), respectively. The N2O release rates at the 5 g x L(-1) and 10 g x L(-1) salinity levels were 3.6 and 17.4 times as high as that at the 0 g x L(-1) salinity level. Under various salinity conditions both the dissolved and releasing state N2O production first increased and then decreased, and the dissolved N2O production was greater than that in the releasing state. In addition, when the salinity was low (less than 5 g x L(-1)), the NH4(+)-N removal rate was less affected and almost the same with the condition of 0 g x L(-1), both over 98%. When the salinity was increased to 10 g x L(-1), the NH4(+)-N removal rate dropped to 70%. Thus, increasing the salinity of wastewater not only affected the system nitrogen removal rate but also increased the amount of N2O production. PMID:25639101

  2. Influência do tipo de material suporte no desempenho de reatores biológicos de leito móvel na remoção de carbono e nitrificação de esgoto sanitário The influence of material support kind on the biological moving bed reactors performance used for the carbon removal and nitrification of sewage

    Directory of Open Access Journals (Sweden)

    Delmira Beatriz Wolff

    2010-06-01

    Full Text Available Neste trabalho foi mostrada a influência do tipo de material suporte: P4 (plástico reciclado rugoso, diâmetro médio de 2,31 mm, densidade de 900 kg.m-3, superfície específica potencial de 2.596 m².m-3sup e P5 (polietileno, pouco rugoso, forma cilíndrica, diâmetro médio de 10 mm, densidade de 880 kg.m-3, superfície específica potencial de 3.075m².m-³sup utilizados em dois reatores biológicos de leito móvel, fluxo contínuo, na remoção de carbono e nitrificação de esgoto sanitário, os quais foram divididos em duas fases, de acordo com a idade do lodo (IL: fase A: IL de 10 dias e fase B: IL de 3 dias. Foram aplicadas cargas orgânicas superficiais médias de 4,0 kgDQO.m-2.d-1 (P4 e de 4,1 kgDQO.m-2.d-1 (P5; e cargas superficiais de nitrogênio de 0,63 kgN.m-2.d-1 (P5 e de 0,66 kgN.m-2.d-1 (P5. Para o material P4, a remoção média foi de 87% de carbono e 83% de nitrogênio (fase A e 80% de carbono e 77% de nitrogênio (fase B. Para o P5, remoção de 63% de carbono e 55% de nitrogênio (Fase A e 59% de carbono e de nitrogênio (fase B. Com base nos resultados obtidos, verificou-se que a remoção de carbono e nitrogênio não foi influenciada pela idade do lodo, mas pelo tipo de material suporte (forma ou características de superfície e superfície disponível para o crescimento da biomassa.This paper presented the influence of material support kind: P4 (rugous recycled plastic, medium diameter of 2.31 mm, density of 900 kg.m-3, specific surface potential of 2,596 m².m-3sup and P5 (polietilene, cilindric shape, medium diameter of 10 mm, density of 880 kg.m-3, specific surface potential of 3,075m².m-3sup used in two continuous flux biological moving bed reactors using different material support to remove nitrogen and carbon from sewage, which was divided in two phases according to sludge retention time (SRT: phase A: SRT of 10 days and phase B: SRT of 3 days. The organic loading rates applied were 4.0 kgCOD.m-2.d-1 (P4 and

  3. Regulatory inhibition of biological tissue mineralization by calcium phosphate through post-nucleation shielding by fetuin-A.

    Science.gov (United States)

    Chang, Joshua C; Miura, Robert M

    2016-04-21

    In vertebrates, insufficient availability of calcium and inorganic phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are usually present at high concentrations throughout bodily fluids-at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this manuscript, we extend mean-field continuum classical nucleationtheory of the growth of clusters to encompass surface shielding. We use this formulation to study the regulation of sedimentation of calcium phosphate salts in biological tissues through the mechanism of post-nuclear shielding of nascent mineral particles by binding proteins. We develop a mathematical description of this phenomenon using a countable system of hyperbolic partial differential equations. A critical concentration of regulatory protein is identified as a function of the physical parameters that describe the system. PMID:27389239

  4. Regulatory inhibition of biological tissue mineralization by calcium phosphate through post-nucleation shielding by fetuin-A

    Science.gov (United States)

    Chang, Joshua C.; Miura, Robert M.

    2016-04-01

    In vertebrates, insufficient availability of calcium and inorganic phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are usually present at high concentrations throughout bodily fluids—at concentrations exceeding the saturation point. This condition leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this manuscript, we extend mean-field continuum classical nucleation theory of the growth of clusters to encompass surface shielding. We use this formulation to study the regulation of sedimentation of calcium phosphate salts in biological tissues through the mechanism of post-nuclear shielding of nascent mineral particles by binding proteins. We develop a mathematical description of this phenomenon using a countable system of hyperbolic partial differential equations. A critical concentration of regulatory protein is identified as a function of the physical parameters that describe the system.

  5. 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

  6. Long-term effects of antibiotics on the elimination of chemical oxygen demand, nitrification, and viable bacteria in laboratory-scale wastewater treatment plants.

    Science.gov (United States)

    Schmidt, Susan; Winter, Josef; Gallert, Claudia

    2012-10-01

    Antibiotics and other pharmaceuticals are contaminants of the environment because of their widespread use and incomplete removal by microorganisms during wastewater treatment. The influence of a mixture of ciprofloxacin (CIP), gentamicin (GM), sulfamethoxazole (SMZ)/trimethoprim (TMP), and vancomycin (VA), up to a final concentration of 40 mg/L, on the elimination of chemical oxygen demand (COD), nitrification, and survival of bacteria, as well as the elimination of the antibiotics, was assessed in a long-term study in laboratory treatment plants (LTPs). In the presence of 30 mg/L antibiotics, nitrification of artificial sewage by activated sludge ended at nitrite. Nitrate formation was almost completely inhibited. No nitrification at all was possible in the presence of 40 mg/L antibiotics. The nitrifiers were more sensitive to antibiotics than heterotrophic bacteria. COD elimination in antibiotic-stressed LTPs was not influenced by ≤20 mg/L antibiotics. Addition of 30 mg/L antibiotic mixture decreased COD removal efficiency for a period, but the LTPs recovered. Similar results were obtained with 40 mg/L antibiotic mixture. The total viable count of bacteria was not affected negatively by the antibiotics. It ranged from 2.2 × 10(6) to 8.2 × 10(6) colony-forming units per milliliter (CFU/mL) compared with the control at 1.4 × 10(6)-6.3 × 10(6) CFU/mL. Elimination of the four antibiotics during phases of 2.4-30 mg/L from the liquid was high for GM (70-90 %), much lower for VA, TMP, and CIP (0-50 %), and highly fluctuating for SMZ (0-95 %). The antibiotics were mainly adsorbed to the sludge and not biodegraded. PMID:22622431

  7. Cultivation of aerobic granules for simultaneous nitrification and denitrification by seeding different inoculated sludge

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; YANG Feng-lin; LIU Yi-hui; ZHANG Xing-wen

    2005-01-01

    Cultivation of aerobic granules for simultaneous nitrification and denitrification in two sequencing batch airlift bioreactors was studied. Conventional activated floc and anaerobic granules served as main two inoculated sludge in the systems. Morphological variations of sludge in the reactors were observed. It was found that the cultivation of aerobic granules was closely associated with the kind of inoculated sludge. Round and regular aerobic granules were prevailed in both reactors, and the physical characteristics of the aerobic granules in terms of settling ability, specific gravity, and ratio of water containing were distinct when the inoculate sludge was different.Aerobic granules formed by seeding activated floc are more excellent in simultaneous nitrification and denitrification than that by aerobic granules formed from anaerobic granules. It was concluded that inoculated sludge plays a crucial role in the cultivation of aerobic granules for simultaneous nitrification and denitrification.

  8. Effect of sludge age on simultaneous nitrification and denitrification in membrane bioreactor.

    Science.gov (United States)

    Hocaoglu, S Murat; Insel, G; Cokgor, E Ubay; Orhon, D

    2011-06-01

    This study evaluated the effect of sludge age on simultaneous nitrification and denitrification in a membrane bioreactor treating black water. A membrane bioreactor with no separate anoxic volume was operated at a sludge age of 20 days under low dissolved oxygen concentration of 0.1-0.2mg/L. Its performance was compared with the period when the sludge age was adjusted to 60 days. Floc size distribution, apparent viscosity, and nitrogen removal differed significantly, together with different biomass concentrations: nitrification was reduced to 40% while denitrification was almost complete. Modelling indicated that both nitrification and denitrification kinetics varied as a function of the sludge age. Calibrated values of half saturation coefficients were reduced when the sludge age was lowered to 20 days. Model simulation confirmed the validity of variable process kinetics for nitrogen removal, specifically set by the selected sludge age. PMID:21507621

  9. 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.

  10. Dynamics of mineral N, water-soluble carbon and potential nitrification in band-steamed arable soil

    DEFF Research Database (Denmark)

    Elsgaard, Lars

    2010-01-01

    Steaming of narrow soil bands prior to sowing is a new technique that reduces the need for intra-row weeding in herbicide-free row crops. However, the steam treatment may eliminate both weed seeds and non-target soil organisms, thereby affecting the nutrient cycling in the soil. This study tested...... the effect of band-steaming on N and C dynamics in a sandy loam soil that was steamed in situ to maximal temperatures of 70-90°C using a prototype band-steamer. Soil samples (0-5 cm depth) were collected during 90 days from band-steamed soil, undisturbed control soil, and control soil treated just...... mechanically with the band-steamer. In the steamed soil, ammonium concentrations increased from 1.1 to 20.3 μg NH4+-N g-1 dry weight during 28 days. This coincided with an immediate and persistent inhibition of potential nitrification (33-61% inhibition during 90 days). Assays of the temperature response of...

  11. 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.

  12. Assessment of nitrification potential in ground water using short term, single-well injection experiments

    Science.gov (United States)

    Smith, R.L.; Baumgartner, L.K.; Miller, D.N.; Repert, D.A.; Böhlke, J.K.

    2006-01-01

    Nitrification was measured within a sand and gravel aquifer on Cape Cod, MA, using a series of single-well injection tests. The aquifer contained a wastewater-derived contaminant plume, the core of which was anoxic and contained ammonium. The study was conducted near the downgradient end of the ammonium zone, which was characterized by inversely trending vertical gradients of oxygen (270 to 0 ??M) and ammonium (19 to 625 ??M) and appeared to be a potentially active zone for nitrification. The tests were conducted by injecting a tracer solution (ambient ground water + added constituents) into selected locations within the gradients using multilevel samplers. After injection, the tracers moved by natural ground water flow and were sampled with time from the injection port. Rates of nitrification were determined from changes in nitrate and nitrite concentration relative to bromide. Initial tests were conducted with 15N-enriched ammonium; subsequent tests examined the effect of adding ammonium, nitrite, or oxygen above background concentrations and of adding difluoromethane, a nitrification inhibitor. In situ net nitrate production exceeded net nitrite production by 3- to 6- fold and production rates of both decreased in the presence of difluoromethane. Nitrification rates were 0.02-0.28 ??mol (L aquifer)-1 h-1 with in situ oxygen concentrations and up to 0.81 ??mol (L aquifer)-1 h-1 with non-limiting substrate concentrations. Geochemical considerations indicate that the rates derived from single-well injection tests yielded overestimates of in situ rates, possibly because the injections promoted small-scale mixing within a transport-limited reaction zone. Nonetheless, these tests were useful for characterizing ground water nitrification in situ and for comparing potential rates of activity when the tracer cloud included non-limiting ammonium and oxygen concentrations. ?? Springer Science+Business Media, Inc. 2005.

  13. Effects of N source and nitrification pretreatment on growth of Arthrospira platensis in human urine

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Culture of Arthrospira platensis (Spirulina platensis) in human urine was investigated to get valuable biomass. NO3-N was the proper N source, in comparison with other N source, includ ing urea, NH4-N and NO2-N. As a result, aerobic nitrification of human urine was performed, with above 93.6% nitrification percentage finally achieved with total-N (TN) load of 46.52those in Zarrouk medium. Thus, it is possible to culture Arthrospiraplatensis in nitrified human urine for food production within bioregenerative life support systems (BLSSs).

  14. Effects of Methane Metabolism on Nitrification and Nitrous Oxide Production in Polluted Freshwater Sediment

    OpenAIRE

    Roy, Réal; Knowles, Roger

    1994-01-01

    We report the effect of CH4 and of CH4 oxidation on nitrification in freshwater sediment from Hamilton Harbour, Ontario, Canada, a highly polluted ecosystem. Aerobic slurry experiments showed a high potential for aerobic N2O production in some sites. It was suppressed by C2H2, correlated to NO3- production, and stimulated by NH4+ concentration, supporting the hypothesis of a nitrification-dependent source for this N2O production. Diluted sediment slurries supplemented with CH4 (1 to 24 μM) sh...

  15. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil

    OpenAIRE

    Banning, Natasha C.; Maccarone, Linda D.; Fisk, Louise M.; Murphy, Daniel V.

    2015-01-01

    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, an...

  16. The Effects of Different Fertilizing Methods on Nitrification and Denitrification in Black Soil in Songnen Plain

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-yu; WANG Hong-yan; WANG Xu-mei; QI Zhi-yong

    2004-01-01

    The paper compared the effects of application of farm manure with chemical fertilizers on nitrification and denitrification in black soil, the result showed that the numbers of nitrobacterias and denitrobacterias in farm manure treatment were both higher than that of other treatments. The intensity of denitrification in chemical treatment was higher than that of manure treatment. The content of organic matter in soil was correlated with the intensity of nitrification and denitrification, and the coefficients were respectively 0.9981 and 0.8693.

  17. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    OpenAIRE

    Sauder, L.A.; Peterse, F.; Schouten, S; Neufeld, J. D.

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidizing populations in nitrifying rotating biological contactors (RBCs) from a municipal wastewater treatment plant. Individual RBC stages are arranged in series, with nitrification at each stage creat...

  18. [Identification of a high ammonia nitrogen tolerant and heterotrophic nitrification-aerobic denitrification bacterial strain TN-14 and its nitrogen removal capabilities].

    Science.gov (United States)

    Xin, Xin; Yao, Li; Lu, Lei; Leng, Lu; Zhou, Ying-Qin; Guo, Jun-Yuan

    2014-10-01

    A new strain of high ammonia nitrogen tolerant and heterotrophic nitrification-aerobic denitrification bacterium TN-14 was isolated from the environment. Its physiological and biochemical characteristics and molecular identification, performences of heterotrophic nitrification-aerobic, the abilities of resistance to ammonia nitrogen as well as the decontamination abilities were studied, respectively. It was preliminary identified as Acinetobacter sp. according to its physiological and biochemical characteristics and molecular identification results. In heterotrophic nitrification system, the ammonia nitrogen and total nitrogen removal rate of the bacterial strain TN-14 could reach 97.13% and 93.53% within 24 h. In nitrates denitrification system, the nitrate concentration could decline from 94.24 mg · L(-1) to 39.32 mg · L(-1) within 24 h, where the removal rate was 58.28% and the denitrification rate was 2.28 mg · (L · h)(-1); In nitrite denitrification systems, the initial concentration of nitrite could be declined from 97.78 mg · L(-1) to 21.30 mg x L(-1), with a nitrite nitrogen removal rate of 78.22%, and a denitrification rate of 2.55 mg · (L· h)(-1). Meanwhile, strain TN-14 had the capability of flocculant production, and the flocculating rate could reach 94.74% when its fermentation liquid was used to treat 0.4% kaolin suspension. Strain TN-14 could grow at an ammonia nitrogen concentration as high as 1200 mg · L(-1). In the aspect of actual piggery wastewater treatment by strain TN-14, the removal rate of COD, ammonia nitrogen, TN and TP cloud reached 85.30%, 65.72%, 64.86% and 79.41%, respectively. Strain TN-14 has a good application prospect in biological treatment of real high- ammonia wastewater. PMID:25693403

  19. Exploiting the MDM2-CK1α protein-protein interface to develop novel biologics that induce UBL-kinase-modification and inhibit cell growth.

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Huart

    Full Text Available Protein-protein interactions forming dominant signalling events are providing ever-growing platforms for the development of novel Biologic tools for controlling cell growth. Casein Kinase 1 α (CK1α forms a genetic and physical interaction with the murine double minute chromosome 2 (MDM2 oncoprotein resulting in degradation of the p53 tumour suppressor. Pharmacological inhibition of CK1 increases p53 protein level and induces cell death, whilst small interfering RNA-mediated depletion of CK1α stabilizes p53 and induces growth arrest. We mapped the dominant protein-protein interface that stabilizes the MDM2 and CK1α complex in order to determine whether a peptide derived from the core CK1α-MDM2 interface form novel Biologics that can be used to probe the contribution of the CK1-MDM2 protein-protein interaction to p53 activation and cell viability. Overlapping peptides derived from CK1α were screened for dominant MDM2 binding sites using (i ELISA with recombinant MDM2; (ii cell lysate pull-down towards endogenous MDM2; (iii MDM2-CK1α complex-based competition ELISA; and (iv MDM2-mediated ubiquitination. One dominant peptide, peptide 35 was bioactive in all four assays and its transfection induced cell death/growth arrest in a p53-independent manner. Ectopic expression of flag-tagged peptide 35 induced a novel ubiquitin and NEDD8 modification of CK1α, providing one of the first examples whereby NEDDylation of a protein kinase can be induced. These data identify an MDM2 binding motif in CK1α which when isolated as a small peptide can (i function as a dominant negative inhibitor of the CK1α-MDM2 interface, (ii be used as a tool to study NEDDylation of CK1α, and (iii reduce cell growth. Further, this approach provides a technological blueprint, complementing siRNA and chemical biology approaches, by exploiting protein-protein interactions in order to develop Biologics to manipulate novel types of signalling pathways such as cross

  20. Inhibitory effect of 30 medical herbs on urea hydrolysis and nitrification%30种中草药植物对尿素水解和硝化作用的抑制效果研究

    Institute of Scientific and Technical Information of China (English)

    史云峰; 兰天; 张丽莉; 赵牧秋

    2015-01-01

    This study was designed to investigate the inhibitory effect of aqueous extracts of 21 families 30 species medical herbs on urea hydrolysis and nitrification in 3 soils with laboratory incubation experiment. The results indicated that aqueous extracts of 23 species medical herbs could inhibit urea hydrolysis, among them 8 species showed better efficacy than urease in-hibitor hydroquinone ( HQ) . The aqueous extracts of 25 species of medical herbs could inhibit nitrification of NH+4 , and 3 a-mong them showed better efficacy than nitrification inhibitor dicyandiamide ( DCD) . Lamiaceae plant Prunella vulgaris and ca-prifoliaceae plant Lonicera japonica could both inhibit urea hydrolysis and nitrification effectively, which could be the best choices as urea synergist. The study results also indicated that the highest urease inhibitory rate appeared at 24~36 h after in-cubation experiment started, and the highest nitrification inhibitory rate appeared at 14~21 d when using powder of Prunella vulgaris and Lonicera japonica as experiment materials. The inhibitory effect of these two kinds of plant powder increased with their increasing dosage.%采用室内培养实验,分别研究了21科30种中草药的植物浸提液对3种土壤中尿素水解和硝化作用的抑制效果。结果表明,中草药植物浸提液能够对尿素水解起抑制作用的有23种,其中8种的抑制效果优于脲酶抑制剂氢醌( HQ);浸提液能够抑制硝化作用的植物有25种,其中3种的硝化抑制效果优于双氰胺( DCD);唇形科植物夏枯草( Prunella vulgaris L.)和忍冬科植物金银花( Lonicera japonica Thunb.)既能有效抑制尿素水解,又能有效减缓NH4+的硝化,是尿基氮肥增效剂的最佳选择。研究还表明,夏枯草和金银花粉末在培养后的24~36 h脲酶抑制率最高,在培养后的14~21 d硝化抑制率最高,且抑制效果随粉末用量的增加而增强。

  1. Optimization of biological phosphorus and ammonia removal in a combined fixed and suspended growth wastewater treatment system: Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    This project was conducted to optimize design and operational criteria for enhanced biological phosphorus removal and nitrification of ammonia in the fixed growth reactor-suspended growth reactor (FGR-SGR) process. The research completed the investigation of optimum hydraulic retention times for biological phosphorus removal in both the unaerated and aerated phases of the suspended growth components of the FGR-SGR system, including an assessment of the possibility of reducing suspended growth aeration requirements by using oxidized forms of nitrogen rather than dissolved oxygen for biological phosphorus uptake; investigated the effects on biological phosphorus removal and nitrification of varying the internal recycle flow rates; and investigated the optimum solids retention time, or the optimum operating mixed liquor suspended solids concentration, in the suspended growth component of the system for biological phosphorus removal and nitrification-denitrification.

  2. Nitrification-denitrification Loss and N2O Emission from Urea Applied to Crop-soil Systems in North China Plain

    Institute of Scientific and Technical Information of China (English)

    DING Hong; CAI Gui-xin; WANG Yue-si; CHEN De-li

    2002-01-01

    Nitrogen losses are not only important for agriculture but environment as well. Field experiments were set up in summer corn field at Fengqiu Agro-Ecological Experimental Station of CAS in North China Plain. The soil was in maize-chao soil. Nitrification-denitrification losses and N2O emission were determined by acetylene-inhibition soil-core incubation method in the soils applied urea. The results showed that urea was fast hydrolyzed and became to nitrate. The soil with non urea released 0.33kg N/ha N2O.However, the soil produced 2.91kg N/ha N2O, about 1.94% of the applied N, when the urea was spread on soil surface. N2O emission reduced to 2.50kg N/ha, about 1.67% of the applied N, when the urea was put in deep soil by digging a hole. The denitrification loss was 1.17kg N/ha in control soil. It increased to 3.00kg N/ha and 2.09kg N/ha, which were 2.00% and 1.39% of the used N, in the soils received urea on surface and sub-surface respectively. It was suggested that nitrification-denitrification was probably not a main way of fertilizer nitrogen loss in this region.

  3. Effect of particulate organic carbon on heterotrophic bacterial populations and nitrification efficiency in biological filters

    OpenAIRE

    Michaud, Luigi; Blancheton, Jean-paul; V. Bruni; Piedrahita, Raul

    2006-01-01

    Competition between heterotrophic and nitrifying bacteria is of major practical importance in aquaculture biofilter design and operation. This competition must be understood to minimize the negative impact of heterotrophic bacteria on an aquaculture system. On the other hand, the heterotrophic population is suspected of having a positive effect against pathogenic bacteria. Little information is available on the bacterial communities present within aquaculture systems, except for nitrifying ba...

  4. Factors influencing biological treatment of MTBE contaminated ground water

    Energy Technology Data Exchange (ETDEWEB)

    Stringfellow, William T.; Hines Jr., Robert D.; Cockrum, Dirk K.; Kilkenny, Scott T.

    2001-09-14

    Methyl tert-butyl ether (MTBE) contamination has complicated the remediation of gasoline contaminated sites. Many sites are using biological processes for ground water treatment and would like to apply the same technology to MTBE. However, the efficiency and reliability of MTBE biological treatment is not well documented. The objective of this study was to examine the operational and environmental variables influencing MTBE biotreatment. A fluidized bed reactor was installed at a fuel transfer station and used to treat ground water contaminated with MTBE and gasoline hydrocarbons. A complete set of chemical and operational data was collected during this study and a statistical approach was used to determine what variables were influencing MTBE treatment efficiency. It was found that MTBE treatment was more sensitive to up-set than gasoline hydrocarbon treatment. Events, such as excess iron accumulation, inhibited MTBE treatment, but not hydrocarbon treatment. Multiple regression analysis identified biomass accumulation and temperature as the most important variables controlling the efficiency of MTBE treatment. The influent concentration and loading of hydrocarbons, but not MTBE, also impacted MTBE treatment efficiency. The results of this study suggest guidelines for improving MTBE treatment. Long cell retention times in the reactor are necessary for maintaining MTBE treatment. The onset of nitrification only occurs when long cell retention times have been reached and can be used as an indicator in fixed film reactors that conditions favorable to MTBE treatment exist. Conversely, if the reactor can not nitrify, it is unlikely to have stable MTBE treatment.

  5. Quantifying the contribution of nitrification and denitrification to the nitrous oxide flux using 15N tracers

    International Nuclear Information System (INIS)

    Microbial transformations of nitrification and denitrification are the main sources of nitrous oxide (N2O) from soils. Relative contributions of both processes to N2O emissions were estimated on an agricultural soil using 15N isotope tracers (15NH4+ or 15NO3-), for a 10-day batch experiment. Under unsaturated and saturated conditions, both processes were significantly involved in N2O production. Under unsaturated conditions, 60% of N-N2O came from nitrification, while denitrification contributed around 85-90% under saturated conditions. Estimated nitrification rates were not significantly different whatever the soil moisture content, whereas the proportion of nitrified N emitted as N2O changed from 0.13 to 2.32%. In coherence with previous studies, we interpreted this high value as resulting from the decrease in O2 availability through the increase in soil moisture content. It thus appears that, under limiting aeration conditions, some values for N2O emissions through nitrification could be underestimated. - Identifying the mechanisms responsible for N2O emission in soils could help define potential mitigation methods

  6. Photo-oxygenation to support nitrification in an algal-bacterial consortium treating artificial wastewater.

    Science.gov (United States)

    Karya, N G A I; van der Steen, N P; Lens, P N L

    2013-04-01

    Oxygenation by photosynthesis in a mixed culture of algae and nitrifiers was investigated for its potential to support nitrification. An open photo-bioreactor (1L fermentor; 30°C) was inoculated with an enriched culture of nitrifiers obtained from activated sludge and a pure culture of Scenedesmus sp. The reactor was illuminated (60 μmol/m2 s) and operated as a sequencing batch reactor with 50% discharge per cycle and sludge retention time of 15 or 30 days. Full nitrification of synthetic wastewater (50 mgNH4+-N/L) without mechanical aeration was achieved after less than 14 cycles (18.5 h React per 24h cycle) and the biomass steadily increased until a concentration of 1.9 g VSS/L with 29 mg chl-a/L. The maximum observed nitrification rate was 7.7 mgNH4+-N/Lh. A mass balance showed that ammonium removal was primarily by nitrification (81-85%) rather than by ammonium uptake by algae. PMID:23500581

  7. Nitrification performance of nitrifying bacteria immobilized in waterborne polyurethane at low ammonia nitrogen concentrations

    Institute of Scientific and Technical Information of China (English)

    Yamei Dong; Zhenjia Zhang; Yongwei Jin; Zhirong Li; Jian Lu

    2011-01-01

    Suspended and waterborne polyurethane immobilized nitrifying bacteria have been adopted for evaluating the effects of environmental changes, such as temperature, dissolved oxygen (DO) concentration and pH, on nitrification characteristics under conditions of low ammonia concentrations.The results showed that nitrification was prone to complete with increasing pH, DO and temperature.Sensitivity analysis demonstrated the effects of temperature and pH on nitrification feature of suspended bacteria were slightly greater than those of immobilized nitrifying bacteria.Immobilized cells could achieve complete nitrification at low ammonia concentrations when DO was sufficient.Continuous experiments were carried out to discuss the removal of ammonia nitrogen from synthetic micropollute source water with the ammonia concentration of about 1 mg/L using immobilized nitrifying bacteria pellets in an up-flow inner circulation reactor under different hydraulic retention times (HRT).The continuous removal rate remains above 80% even under HRT 30 min.The results verified that the waterborne polyurethane immobilized nitrifying bacteria pellets had great potential applications for micro-pollution source water treatment.

  8. In situ net N mineralisation and nitrification under organic and conventionally managed olive oil orchards

    DEFF Research Database (Denmark)

    Gomez Muñoz, Beatriz; Hinojosa, M. B.; García-Ruiz, R.

    2015-01-01

    ) and nitrification (NN) were investigated during a year in comparable organic (OR) and conventional (CV) olive oil orchards of two locations differing their N input. Soil samples were collected in two soil positions (under and between trees canopy) and both buried-bags and soil core techniques were...

  9. Arbuscular Mycorrhiza Prevents Suppression of Actual Nitrification Rates in the (Myco-)Rhizosphere of Plantago lanceolata

    Institute of Scientific and Technical Information of China (English)

    S.D.VERESOGLOU

    2012-01-01

    The vast majority of herbaceous plants engage into arbuscular mycorrhizal (AM) symbioses and consideration of their mycorrhizal status should be embodied in studies of plant-microbe interactions.To establish reliable AM contrasts,however,a sterilized re-inoculation procedure is commonly adopted.It was questioned whether the specific approach is sufficient for the studies targeting the bacterial domain,specifically nitrifiers,a group of autotrophic,slow growing microbes.In a controlled experiment mycorrhizal and non-mycorrhizal Plantago lanceolata were grown up in compartmentalized pots to study the AM effect on nitrification rates in the plant rhizosphere.Nitrification rates were assayed following an extensive 3-week bacterial equilibration step of the re-inoculated soil and a 13-week plant growth period in a controlled environment.Under these specific conditions,the nitrification potential levels at harvest were exceptionally low,and actual nitrification rates of the root compartment of non-mycorrhizal P.lanceolata were significantly lower than those of any other compartment.It is then argued that the specific effects should be attributed to the alleged higher growth rates of non-mycorrhizal plants that are known to occur early in the AM experiment.It is concluded that the specific experimental approach is not suitable for the study of microbes with slow growth rates.

  10. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    Institute of Scientific and Technical Information of China (English)

    Brooke B.OSBORNE; Jill S.BARON; Matthew D.WALLENSTEIN

    2016-01-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many high-elevation ecosystems.The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses.In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity,we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash,talus,and meadow).We found that bacteria,not archaea,dominated all ammonia oxidizer communities.Nitrification increased with moisture in all soils and under all temperature treatments.However,temperature was not correlated with nitrification rates in all soils.Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes.Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  11. Influence of operating conditions on nitrous oxide formation during nitritation and nitrification.

    Science.gov (United States)

    Schneider, Y; Beier, M; Rosenwinkel, K-H

    2014-10-01

    Nitrous oxide (N2O), a strong greenhouse gas, can be produced by ammonium-oxidizing bacteria (AOB) as a by-product of ammonium oxidation and can potentially be formed in all types of nitrification processes. However, partial nitritation has been reported to cause significantly higher N2O emissions than complete nitrification. In the study presented here, the mechanisms and factors that drive N2O formation by AOB were investigated with respect to different operational strategies to achieve nitrite accumulation base on combined evaluation of oxygen uptake rate (OUR) and N2O formation rate. On the one hand, N2O formation during partial nitritation and nitrification in a continuously stirred tank reactor (CSTR) with continuous aerobic conditions was observed. On the other hand, the effect of intermittent aeration on N2O formation during nitrification was investigated. The presence of nitrite, the extend of sludge-specific ammonium loading, low oxygen concentration, and transition from aerobic to anoxic conditions significantly increased N2O formation in this reactor independently from each other, indicating that different formation pathways, supposedly via nitrite or hydroxylamine, were active. PMID:24928380

  12. Effect of nitrification inhibitors on yield and essential oil contents of japanese Mint

    International Nuclear Information System (INIS)

    Pyrethrum (Chrysanthemum cinerariefolium) flowers have been observed to have insecticidal properties and could be also used as indigenous nitrification-inhibitors for increasing N-use efficiency. During 1998 and 1999 a study was conducted to evaluate the relative performance of pyrethrum flower waste and Dicyandiamide (DCD) as nitrification inhibitors, applied with prilled urea (PU), to Japanese mint (Mentha arvensis L.). Application of the nitrification inhibitors with prilled urea significantly increased the growth and menthol contents of the crop, compared to that of prilled urea alone. Addition of Dicyandiamide (DCD) and pyrethrum flower waste gave 30 and 23% more herb-yield that prilled urea alone, the corresponding increase in oil-yield being 27 and 22%, respectively. Application of nitrogen enhanced the growth and menthol contents of crop to more than 300 kg N ha/sup -1/ with prilled urea. Both the materials improved the N-use efficiency by one and half time, as compared to PU at 1200 kg N ha/sup -1/. The results indicate that pyrethru nitrification inhibitor. (author)

  13. Nitrification in brackish water recirculating aquaculture system integrated with activated packed bed bioreactor.

    Science.gov (United States)

    Rejish Kumar, V J; Joseph, Valsamma; Philip, Rosamma; Bright Singh, I S

    2010-01-01

    Recirculation aquaculture systems (RAS) depend on nitrifying biofilters for the maintenance of water quality, increased biosecurity and environmental sustainability. To satisfy these requirements a packed bed bioreactor (PBBR) activated with indigenous nitrifying bacterial consortia has been developed and commercialized for operation under different salinities for instant nitrification in shrimp and prawn hatchery systems. In the present study the nitrification efficiency of the bioreactor was tested in a laboratory level recirculating aquaculture system for the rearing of Penaeus monodon for a period of two months under higher feeding rates and no water exchange. Rapid setting up of nitrification was observed during the operation, as the volumetric total ammonia nitrogen removal rates (VTR) increased with total ammonia nitrogen (TAN) production in the system. The average Volumetric TAN Removal Rates (VTR) at the feeding rate of 160 g/day from 54-60th days of culture was 0.1533+/-0.0045 kg TAN/m(3)/day. The regression between VTR and TAN explained 86% variability in VTR (P<0.001). The laboratory level RAS demonstrated here showed high performance both in terms of shrimp biomass yield and nitrification and environmental quality maintenance. Fluorescent in-situ Hybridization analysis of the reactor biofilm ensured the presence of autotrophic nitrifier groups such as Nitrosococcus mobilis lineage, Nitrobacter spp and phylum Nitrospira, the constituent members present in the original consortia used for activating the reactors. This showed the stability of the consortia on long term operation. PMID:20150717

  14. Large-scale demonstration of the sulfate reduction autotrophic denitrification nitrification integrated (SANI(®)) process in saline sewage treatment.

    Science.gov (United States)

    Wu, Di; Ekama, George A; Chui, Ho-Kwong; Wang, Bo; Cui, Yan-Xiang; Hao, Tian-Wei; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2016-09-01

    Recently, the Sulfate reduction Autotrophic denitrification Nitrification Integrated (SANI(®)) process was developed for the removal of organics and nitrogen with sludge minimization in the treatment of saline sewage (with a Sulfate-to-COD ratio > 0.5 mg SO4(2-)-S/mg COD) generated from seawater used for toilet flushing or salt water intrusion. Previously investigated in lab- and pilot-scale, this process has now been scaled up to a 800-1000 m(3)/d full-scale demonstration plant. In this paper, the design and operating parameters of the SANI demo plant built in Hong Kong are analyzed. After a 4-month start-up period, a stable sulfur cycle-based biological nitrogen removal system having a hydraulic retention time (HRT) of 12.5 h was developed, thereby reducing the amount of space needed by 30-40% compared with conventional activated sludge (CAS) plants in Hong Kong. The demo plant satisfactorily met the local effluent discharge limits during both the summer and winter periods. In winter (sewage temperature of 21 ± 1 °C), the maximum volumetric loading rates for organic conversion, nitrification, and denitrification were 2 kg COD/(m(3)·d), 0.39 kg N/(m(3)·d), and 0.35 kg N/(m(3)·d), respectively. The biological sludge production rate of SANI process was 0.35 ± 0.08 g TSSproduced/g BOD5 (or 0.19 ± 0.05 g TSS/g COD), which is 60-70% lower than that of the CAS process in Hong Kong. While further process optimization is possible, this study demonstrates the SANI process can be potentially implemented for the treatment of saline sewage. PMID:27232994

  15. Nitrification and its oxygen consumption along the turbid Chang Jiang River plume

    Science.gov (United States)

    Hsiao, S. S.-Y.; Hsu, T.-C.; Liu, J.-w.; Xie, X.; Zhang, Y.; Lin, J.; Wang, H.; Yang, J.-Y. T.; Hsu, S.-C.; Dai, M.; Kao, S.-J.

    2014-04-01

    Nitrification is a series of processes that oxidizes ammonia to nitrate, which contributes to hypoxia development in coastal oceans, especially in eutrophicated regions. The nitrification rate of bulk water (NRb) and particle free water (NRpf, particle > 3 μm eliminated) were determined along the Chang Jiang River plume in August 2011 by nitrogen isotope tracer technique. Measurements of dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen (DON), total suspended matter (TSM), particulate organic carbon/nitrogen (POC / PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial ammonia monooxygenase subunit A gene (amoA) abundance on size-fractioned particles (> 3 μm and 0.22-3 μm) were conducted. The NRb ranged from undetectable up to 4.6 μmol L-1 day-1, peaking at a salinity of ~ 29. NRb values were positively correlated with ammonium concentration, suggesting the importance of substrate in nitrification. In the river mouth and the inner plume, NRb was much higher than NRpf, indicating that the nitrifying microorganism is mainly particle associated, which was supported by its significant correlation with amoA gene abundance and TSM concentration. The estimated oxygen demands of nitrification accounted for 0.32 to 318% of CR, in which 50% samples demanded more oxygen than that predicted by by the Redfield model (23%), indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg-1) throughout the observation period. The excess nitrification-associated oxygen demand (NOD) showed a tendency to occur at lower DO samples accompanied by higher acid-leachable Fe / Mn, which implied reactive Fe3+ / Mn4+ may play a role as oxidant in the nitrification process. Stoichiometric calculation suggested that reactive Fe on particles was 10 times the oxidant demand required to complete ammonia oxidation in the entire plume. The potential involvement of reactive

  16. Biological removal of nitrogen from waste water

    Energy Technology Data Exchange (ETDEWEB)

    Dombrowski, T.; Lompe, D.; Wiesmann, U.

    1989-02-01

    The biological treatment of waste water with both a high organic (2500 mg/l DOC) and high ammonia concentration (600 mg/l NH/sub 4//sup +/-N) was investigated. The first step consists of a two step anaerobic cascade of fixed bed loop reactors with polyurethan foam particles as support material for bacterica. The aerobic treatment occurs in two aerated stirred tanks with sedimentation tanks and two separate sludge recycle systems each for heterotrophic and autotrophic biomass resulting in a degradation of organic compounds (first tank) and nitrification (second tank). Finally the nitrate is reduced by biological denitrification. By optimization the total hydraulic retention time could be reduced to 7 hr. Nitrification is the most sensitive step and can be on-line controlled by measurement of oxygen consumption.

  17. Label-free colorimetric detection of biological thiols based on target-triggered inhibition of photoinduced formation of AuNPs

    Science.gov (United States)

    Lim Jung, Ye; Park, Jung Hun; Kim, Moon Il; Park, Hyun Gyu

    2016-02-01

    A label-free colorimetric method for the detection of biological thiols (biothiols) was developed. This method is based on prevention of the photoinduced reduction of auric ions (Au(III)) in the presence of amino acids (acting as a reducing agent) by biothiols; the photoinduced reduction is inhibited due to the strong interaction of the biothiols with Au(III). In this method, the sample was first incubated in an assay solution containing Au(III) and threonine; the sample solution was then exposed to 254 nm UV light. For samples without biothiols, this process led to the photoreduction of Au(III) followed by growth of gold nanoparticles accompanied by the visually detectable development of a red coloration typified by an absorption peak at ca 530 nm. Conversely, in the presence of biothiols, reduction of Au(III) to Au(0) was prevented by entrapment of Au(III) within the biothiols via the thiol group. The solution thus remained colorless even after UV irradiation, which was used as an indicator of the presence of biothiols. Using this strategy, biothiols were very conveniently analyzed by monitoring color changes of the samples with the naked eye or a UV-vis spectrometer. The strategy based on this interesting phenomenon exhibited high selectivity toward biothiols over common amino acids and was successfully employed for reliable quantification of biothiols present in human plasma, demonstrating its great potential for clinical applications.

  18. Impact of water boundary layer diffusion on the nitrification rate of submerged biofilter elements from a recirculating aquaculture system.

    Science.gov (United States)

    Prehn, Jonas; Waul, Christopher K; Pedersen, Lars-Flemming; Arvin, Erik

    2012-07-01

    Total ammonia nitrogen (TAN) removal by microbial nitrification is an essential process in recirculating aquaculture systems (RAS). In order to protect the aquatic environment and fish health, it is important to be able to predict the nitrification rates in RAS's. The aim of this study was to determine the impact of hydraulic film diffusion on the nitrification rate in a submerged biofilter. Using an experimental batch reactor setup with recirculation, active nitrifying biofilter units from a RAS were exposed to a range of hydraulic flow velocities. Corresponding nitrification rates were measured following ammonium chloride, NH₄Cl, spikes and the impact of hydraulic film diffusion was quantified. The nitrification performance of the tested biofilter could be significantly increased by increasing the hydraulic flow velocity in the filter. Area based first order nitrification rate constants ranged from 0.065 m d⁻¹ to 0.192 m d⁻¹ for flow velocities between 2.5 m h⁻¹ and 40 m h⁻¹ (18 °C). This study documents that hydraulic film diffusion may have a significant impact on the nitrification rate in fixed film biofilters with geometry and hydraulic flows corresponding to our experimental RAS biofilters. The results may thus have practical implications in relation to the design, operational strategy of RAS biofilters and how to optimize TAN removal in fixed film biofilter systems. PMID:22507250

  19. Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product

    Institute of Scientific and Technical Information of China (English)

    YU De-shuang; PENG Yong-zhen; ZHANG Kui

    2004-01-01

    The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end productwas studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and veryhigh levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 ℃, pH 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl- 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much highchlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrificationto nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the totaldomestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organicsdeclined obviously(less than 60% ). It was found that the effect of seawater salinity on the removal of organics wasnegative rather than positive one as shown for ammonia removal.

  20. Insulin-like growth factor (IGF) binding protein from human decidua inhibits the binding and biological action of IGF-I in cultured choriocarcinoma cells

    International Nuclear Information System (INIS)

    The placenta expresses genes for insulin-like growth factors (IGFs) and possesses IGF-receptors, suggesting that placental growth is regulated by IGFs in an autocrine manner. We have previously shown that human decidua, but not placenta, synthesizes and secretes a 34 K IGF-binding protein (34 K IGF-BP) called placental protein 12. We now used human choriocarcinoma JEG-3 cell monolayer cultures and recombinant (Thr59)IGF-I as a model to study whether the decidual 34 K IGF-BP is able to modulate the receptor binding and biological activity of IGFs in trophoblasts. JEG-3 cells, which possess type I IGF receptors, were unable to produce IGF-BPs. Purified 34 K IGF-BP specifically bound [125I]iodo-(Thr59)IGF-I. Multiplication-stimulating activity had 2.5% the potency of (Thr59)IGF-I, and insulin had no effect on the binding of [125I] iodo-(Thr59)IGF-I. 34 K IGF-BP inhibited the binding of [125I] iodo-(Thr59)IGF-I to JEG-3 monolayers in a concentration-dependent manner by forming with the tracer a soluble complex that could not bind to the cell surface as demonstrated by competitive binding and cross-linking experiments. After incubating the cell monolayers with [125I]iodo-(Thr59)IGF-I in the presence of purified binding protein, followed by cross-linking, no affinity labeled bands were seen on autoradiography. In contrast, an intensely labeled band at 40 K was detected when the incubation medium was analyzed, suggesting that (Thr59)IGF-I and 34 K IGF-BP formed a complex in a 1:1 molar ratio. Also, 34 K IGF-BP inhibited both basal and IGF-I-stimulated uptake of alpha-[3H]aminoisobutyric acid in JEG-3 cells. RNA analysis revealed that IGF-II is expressed in JEG-3 cells

  1. Insulin-like growth factor (IGF) binding protein from human decidua inhibits the binding and biological action of IGF-I in cultured choriocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Ritvos, O.; Ranta, T.; Jalkanen, J.; Suikkari, A.M.; Voutilainen, R.; Bohn, H.; Rutanen, E.M.

    1988-05-01

    The placenta expresses genes for insulin-like growth factors (IGFs) and possesses IGF-receptors, suggesting that placental growth is regulated by IGFs in an autocrine manner. We have previously shown that human decidua, but not placenta, synthesizes and secretes a 34 K IGF-binding protein (34 K IGF-BP) called placental protein 12. We now used human choriocarcinoma JEG-3 cell monolayer cultures and recombinant (Thr59)IGF-I as a model to study whether the decidual 34 K IGF-BP is able to modulate the receptor binding and biological activity of IGFs in trophoblasts. JEG-3 cells, which possess type I IGF receptors, were unable to produce IGF-BPs. Purified 34 K IGF-BP specifically bound (125I)iodo-(Thr59)IGF-I. Multiplication-stimulating activity had 2.5% the potency of (Thr59)IGF-I, and insulin had no effect on the binding of (125I) iodo-(Thr59)IGF-I. 34 K IGF-BP inhibited the binding of (125I) iodo-(Thr59)IGF-I to JEG-3 monolayers in a concentration-dependent manner by forming with the tracer a soluble complex that could not bind to the cell surface as demonstrated by competitive binding and cross-linking experiments. After incubating the cell monolayers with (125I)iodo-(Thr59)IGF-I in the presence of purified binding protein, followed by cross-linking, no affinity labeled bands were seen on autoradiography. In contrast, an intensely labeled band at 40 K was detected when the incubation medium was analyzed, suggesting that (Thr59)IGF-I and 34 K IGF-BP formed a complex in a 1:1 molar ratio. Also, 34 K IGF-BP inhibited both basal and IGF-I-stimulated uptake of alpha-(3H)aminoisobutyric acid in JEG-3 cells. RNA analysis revealed that IGF-II is expressed in JEG-3 cells.

  2. Transcriptional and physiological responses of nitrifying bacteria to heavy metal inhibition

    Science.gov (United States)

    Heavy metals have been shown to inhibit nitrification, a key process in the removal of nitrogen in wastewater treatment plants. In the present study, the effects of nickel, zinc, lead and cadmium on nitrifying enrichment cultures were studied in batch reactors. The transcriptiona...

  3. Mathematical modelling of biological processor for waste water treatment i sequencing batch reactors; Modellazione matematica di processi biologici per il trattamento delle acque reflue in reattori SBR

    Energy Technology Data Exchange (ETDEWEB)

    Spagni, A.; Bortone, E. [ENEA Centro Ricerche Bologna, Bologna (Italy). Sez. Depurazione e Ciclo dell' Acqua; Ratini, P. [SPES s.r.l., Fabriano, AN (Italy); Marsilli Libelli, S. [Florence Univ., Florence (Italy). Dipt. dei Sistemi e di Informatica

    2000-01-01

    The work shows a mathematical model based on the activated sludge model 2d of the IAWQ (International Association on Water Quality) for biological waste water treatment simulation. Ammonia inhibition and nitrite intermediate in the nitrification and denitrification processes have been added to the ASM2d. The modified model was calibrated and validated with experimental data of a lab scale SBR plant. The modified model is able to precisely fit experimental data. [Italian] Viene presentato un modello matematico sviluppato a partire dall'activated sludge model 2d dell'IAWQ (International Association on Water Quality) per il trattamento biologico dei reflui. Il modello viene integrato dall'introduzione delle cinetiche dell'inibizione nella nitrificazione e denitrificazione. Il modello e' stato calibrato e validato utilizzando dati sperimentali provenienti da un impianto SBR da laboratorio. Il modello e' in grado di prevedere in modo ragionevole le cinetiche degli inquinanti monitorati nella varie prove.

  4. DEVELOPMENT OF TECHNOLOGY OF MODERNIZATION OF BIOLOGICAL WASTEWATER TREATMENT PLANTS

    OpenAIRE

    Gogina Elena Sergeevna; Kulakov Artem Alekseevich

    2012-01-01

    This paper addresses the biological treatment of wastewater associated with removal of nitrogen. Results of laboratory experiments that involve nitrification and denitrification are also presented and analyzed in the paper. Discharges of inadequately treated and untreated wastewater have a negative impact on the aquatic ecosystem. The biological treatment of the wastewater that includes denitrification is strongly influenced by external factors. They need thorough research at t...

  5. Impact of solid retention time and nitrification capacity on the ability of activated sludge to remove pharmaceuticals

    DEFF Research Database (Denmark)

    Falås, Per; Andersen, Henrik Rasmus; Ledin, Anna;

    2012-01-01

    Removal of five acidic pharmaceuticals (ibuprofen, ketoprofen, naproxen, diclofenac and clofibric acid) by activated sludge from five municipal activated sludge treatment processes, with various sludge ages and nitrification capacities, was assessed through batch experiments. The increase in aero...

  6. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification

    NARCIS (Netherlands)

    Braeckman, U.; Van Colen, C.; Guilini, K.; Van Gansbeke, D.; Soetaert, K.; Vincx, M.; Vanaverbeke, J.

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable an

  7. Development and implementation of an expert system to improve the control of nitrification and denitrification in the Vic wastewater treatment plant.

    Science.gov (United States)

    Ribas, F; Rodríguez-Roda, I; Serrat, J; Clara, P; Comas, J

    2008-05-01

    Wastewater treatment plants employ various physical, chemical and biological processes to reduce pollutants from raw wastewater. One of the most important is the biological nitrogen removal process through nitrification and denitrification steps taking place in various sections of the biological reactor. One of the most extensively used configurations to achieve the biological nitrogen removal is an activated sludge system using oxidation ditch or extended aeration. To improve nitrogen removal in the wastewater treatment plant (WWTP) of Vic (Catalonia, NE Spain), the automatic aeration control system was complemented with an Expert System to always provide the most appropriate aeration or anoxia sequence based on the values of ammonium and nitrates given by an automatic analyzer. This article illustrates the development and implementation of this knowledge-based system within the framework of a Decision Support System, which performs SCADA functions. The paper also shows that the application of the decision support system in the Vic WWTP resulted in significant improvements to the biological nitrogen removal. PMID:18661742

  8. Nitritation and N2O Emission in a Denitrification and Nitrification Two-Sludge System Treating High Ammonium Containing Wastewater

    OpenAIRE

    Guangxue Wu; Derui Zheng; Lizhen Xing

    2014-01-01

    The effective management of high ammonium containing wastewater is important for the sustainable development of the wastewater industry. A pre-denitrification and post-nitrification two-sludge system was proposed to treat high ammonium containing wastewater with low carbon-to-nitrogen (C/N) ratios. In the system, pre-denitrification was adopted to use organic carbon in raw wastewater efficiently for nitrogen removal, while post-nitrification was adopted to achieve nitritation. System performa...

  9. Turbid Bottom Waters and Ammonium-Rich Freshwaters as Nitrification Hotspots in a Large Urban Estuary (San Francisco Bay, CA)

    Science.gov (United States)

    Damashek, J.; Casciotti, K. L.; Francis, C.

    2015-12-01

    Nitrification is the link between reduced and oxidized forms of inorganic nitrogen, and is therefore a crucial step in the estuarine nitrogen cycle. Ammonia-oxidizing microorganisms catalyze the rate-limiting step of ammonia oxidation to nitrite and thus play key roles in the biogeochemical cycling nutrient-rich estuaries. Yet, few studies have measured nitrification rates in tandem with ammonia oxidizer functional gene (amoA) expression, abundance, and diversity in estuary waters. Here, we present a multi-year data set on the microbial ecology and biogeochemistry of nitrification in the San Francisco Bay-Delta, the largest estuary on the North American west coast, collected throughout all regions of the estuary from 2012 to 2014. Data on microbial community distributions use functional gene-based PCR assays to assess the diversity, abundance, and mRNA expression of ammonia oxidizers, while stable isotope tracer experiments were used to measure nitrification rates. Ammonia-oxidizing archaea (AOA) typically outnumbered ammonia-oxidizing bacteria (AOB) throughout the sampled gradient, though the relative abundance of AOB was often greater in brackish regions. mRNA expression of amoA appeared to largely track DNA abundance, but suggested only a fraction of the ammonia-oxidizing community was typically active. AOA were always numerically dominant in the Sacramento River, where average nitrification rates were highest, suggesting the AOA communities in this river are responsible for a relatively constant nitrification hotspot. Additionally, depth profiles of nitrification rates suggested high biogeochemical activity near the sediment-water interface in samples with abnormally high turbidity, indicating similar but transient nitrification hotspots in bottom waters containing resuspended sediments. This work increases our knowledge of the ecology and dynamics of ammonia oxidizers in the San Francisco Bay-Delta, with time series data allowing for the putative

  10. Controls of oxygen isotope ratios of nitrate formed during nitrification in soils

    International Nuclear Information System (INIS)

    The isotopic composition of nitrate is increasingly used to determine sources and transformations of nitrogen in terrestrial and aquatic ecosystems. Oxygen isotope ratios of nitrate appear to be particularly useful, since they allow the differentiation between nitrate from atmospheric deposition (δ18Onitrate between +25 and +70 per mille), nitrate from fertilizers (δ18Onitrate +23 per mille), and nitrate derived from nitrification processes in soils (δ18Onitrate 3 molecule derive from H2O (with negative δ18O values dependent upon location) and one oxygen derives from atmospheric O2 (δ18O = +23.5 per mille).. The objective of this study was to experimentally determine the extent to which water oxygen controls the δ18O value of nitrate, which is formed during nitrification in soils

  11. Occurrence of nitrification-denitrification and gaseous nitrogen loss process in flooded rice soil

    Institute of Scientific and Technical Information of China (English)

    NI Wuzhong; LI Jianping; ZHU Zhaoliang

    2007-01-01

    Flooding in wetland rice fields soon after transplanting results in displacement of soil air (including O2). Thus any dissolved O2 in the pore water is consumed out by microbial respiration in a short period. Supply of O2 to the flooded rice soil is by diffusion of O2 through the standing floodwater and consumption at the soil-water interface, and by exudation of O2 by rice roots and subsequent diffusion of O2 into the rhizosphere. The greater potential consumption of O2 compared to the renewal rate results in the development of distinct soil layers: oxidized soil layers under soil-water interface and in the rhizosphere, and reduced soil layers or reduced bulk soil. Nitrification in oxidized soils and denitrification in reduced soils have been known. Currently, denitrification in oxidized soils, even in standing floodwater, has also been identified. In this article, we present a modified nitrification and denitrification occurring mechanism in flooded rice soil.

  12. Effects of drying on nitrification activity in zeoponic medium used for long-term space missions

    Science.gov (United States)

    McGilloway, R. L.; Weaver, R. W.

    2004-01-01

    One component of a proposed life support system is the use of zeoponic substrates, which slowly release NH4+ into "soil" solution, for the production of plants. Nitrifying bacteria that convert NH4+ to NO3- are among the important microbial components of these systems. Survival of nitrifying bacteria in dry zeoponic substrates is needed, because the substrate would likely be stored in an air-dry state between croppings. Substrate was enriched for nitrifying bacteria and allowed to air-dry in a laminar flow hood. Stored substrate was analyzed for nitrifier survivability by measuring nitrifier activity at the beginning, 3 days, 1, 2, and 3 weeks. After rewetting, activity was approximately 9 micrograms N g-1 h-1 regardless of storage time. Nitrification rates did not decrease during storage. It seems unlikely that drying between plantings would result in practical reductions in nitrification, and reinoculation with nitrifying bacteria would not be necessary.

  13. Numerical modeling of coupled nitrification-denitrification in sediment perfusion cores from the hyporheic zone of the Shingobee River, MN

    Science.gov (United States)

    Sheibley, R.W.; Jackman, A.P.; Duff, J.H.; Triska, F.J.

    2003-01-01

    Nitrification and denitrification kinetics in sediment perfusion cores were numerically modeled and compared to experiments on cores from the Shingobee River MN, USA. The experimental design incorporated mixing groundwater discharge with stream water penetration into the cores, which provided a well-defined, one-dimensional simulation of in situ hydrologic conditions. Ammonium (NH+4) and nitrate (NO-3) concentration gradients suggested the upper region of the cores supported coupled nitrification-denitrification, where groundwater-derived NH+4 was first oxidized to NO-3 then subsequently reduced via denitrification to N2. Nitrification and denitrification were modeled using a Crank-Nicolson finite difference approximation to a one-dimensional advection-dispersion equation. Both processes were modeled using first-order reaction kinetics because substrate concentrations (NH+4 and NO-3) were much smaller than published Michaelis constants. Rate coefficients for nitrification and denitrification ranged from 0.2 to 15.8 h-1 and 0.02 to 8.0 h-1, respectively. The rate constants followed an Arrhenius relationship between 7.5 and 22 ??C. Activation energies for nitrification and denitrification were 162 and 97.3 kJ/mol, respectively. Seasonal NH+4 concentration patterns in the Shingobee River were accurately simulated from the relationship between perfusion core temperature and NH+4 flux to the overlying water. The simulations suggest that NH+4 in groundwater discharge is controlled by sediment nitrification that, consistent with its activation energy, is strongly temperature dependent. ?? 2003 Elsevier Ltd. All rights reserved.

  14. Alternating nitrification-denitrification via nitrite for nitrogen removal from soybean wastewater by SBR with real-time control

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-ying; GAO Da-wen; PENG Yong-zhen; WANG Peng; YANG Qing

    2004-01-01

    Anew treating technology for complete nitrogen removal from soybean wastewater with high nitrogen concentrations was studied. Nitrification-denitrification via nitrite was performed in three kinds of operation condition, i.e. nitrification-denitrification via nitrite under traditional SBR process, nitrification- denitrification via nitrite by alternating oxic/anoxic under fixed-time control and nitrification- denitrification via nitrite by alternating oxic/anoxic under on-line fuzzy control. As a result, nitrification-denitrification via nitrite by alternating oxic/anoxic under on-line fuzzy control was the best. It not only improve both nitrification and denitrification rates and decrease total reaction time, but also, save the amount of adding carbon source and alkalinity. Also real-time fuzzy control aeration and mixing time could shorten reaction time and save operation cost. So this method enhanced the efficiency and the stability of nitrogen removal together with, and made operation costs and construction invest to be reduced in the process of wastewater .

  15. Microbial nitrification in Mediterranean sponges: Possible involvement of ammonium-oxidizing Betaproteobacteria

    OpenAIRE

    Bayer, Kristina; Schmitt, Susanne; Hentschel, Ute

    2008-01-01

    The aim of this study was to assess the potential for nitrification in Aplysina aerophoba Schmidt 1862 using a combined physiological and molecular approach. Whole animals were incubated in experimental aquaria and the concentrations of ammonia, nitrate and nitrite were determined in the incubation water using colorimetric assays. Nitrate excretion rates reached values of up to 3.6 μmol g-1 fresh weight day-1 (equivalent to 830 nmol g-1 dry weight h-1) and were matched by ammonia ...

  16. The importance of surface properties in the selection of supports for nitrification in airlift bioreactors

    OpenAIRE

    Teixeira, P.; Oliveira, Rosário

    1998-01-01

    The selection of the supports for biomass immobilisation is of great importance to obtain a stable biofilm leading to a high nitrification efficiency. In this work five type of supports were assayed in external loop air-lift reactors: sand, limestone, basalt, pumice and poraver. The efficiencies of the supports were compared and discussed in terms of their surface-properties: surface free energy of interaction, surface charge, porosity and shape. The results showed tha...

  17. Nitrification and methane oxidation at the sediment surface in Hamilton Harbour (Lake Ontario)

    International Nuclear Information System (INIS)

    Nitrification and methane oxidation in profundal and littoral sediment surfaces of a polluted system were investigated by means of pore water analyses, enumeration of methanotrophic and nitrifying bacteria, and slurry experiments. Sediment CH4 concentrations (0.38-3.4 mM) were generally higher than NH4+ concentrations (0.35-1.4 mM) at the profundal site but not at the littoral site where CH4 and NH4+ concentrations were 0.10-0.93 and 0.12-0.46 mM, respectively. Methanotroph counts (105 cfu·mL-1) were at least an order of magnitude higher than those of NH4+ -oxidizing bacteria (103-104 MPN·mL-1). Dissolved O2 profiles indicated a penetration of 0.5-2.0 mm (profundal) and 2.5-6.0 mm (littoral) which suggests that actual oxidation of CH4 and NH4+ was restricted to this oxic layer. Calculated fluxes of CH4 (0-23 mmol·M-2·d-1), NH4+ (0-2.5 mmol·-2·d-1), and O2 (-14 mmol·-2·d-1) through the surface sediment suggested that CH4 consumption could account for a more important fraction of the estimated O2 consumption than could nitrification. We conclude that: CH4 metabolism may be more important than nitrification as a sink of hypolimnetic O2 in Hamilton Harbour; and CH4 may suppress nitrification by competition for O2 and NH4+ between methanotrophs and nitrifiers. (author). 29 refs., 5 figs

  18. 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...

  19. A study of nitrification in lakes of the English Lake District

    OpenAIRE

    Hall, Grahame

    1981-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University. Nitrification became the dominant nitrogen transformation in a number of lakes which accumulated ammonium, in hypolimnetic water, under aerobic conditions. The timing and duration of this activity varied between lakes but was characterized by decreasing ammonium, and increasing nitrate, concentrations. In Grasmere lake this phase was found to be due to the activity of planktonic chemol...

  20. A cross-site comparison of factors influencing soil nitrification rates in northeastern USA forested watersheds

    Science.gov (United States)

    Ross, D.S.; Wemple, B.C.; Jamison, A.E.; Fredriksen, G.; Shanley, J.B.; Lawrence, G.B.; Bailey, S.W.; Campbell, J.L.

    2009-01-01

    Elevated N deposition is continuing on many forested landscapes around the world and our understanding of ecosystem response is incomplete. Soil processes, especially nitrification, are critical. Many studies of soil N transformations have focused on identifying relationships within a single watershed but these results are often not transferable. We studied 10 small forested research watersheds in the northeastern USA to determine if there were common factors related to soil ammonification and nitrification. Vegetation varied between mixed northern hardwoods and mixed conifers. Watershed surface soils (Oa or A horizons) were sampled at grid or transect points and analyzed for a suite of chemical characteristics. At each sampling point, vegetation and topographic metrics (field and GIS-based) were also obtained. Results were examined by watershed averages (n = 10), seasonal/watershed averages (n = 28), and individual sampling points (n = 608). Using both linear and tree regression techniques, the proportion of conifer species was the single best predictor of nitrification rates, with lower rates at higher conifer dominance. Similar to other studies, the soil C/N ratio was also a good predictor and was well correlated with conifer dominance. Unlike other studies, the presence of Acer saccharum was not by itself a strong predictor, but was when combined with the presence of Betula alleghaniensis. Topographic metrics (slope, aspect, relative elevation, and the topographic index) were not related to N transformation rates across the watersheds. Although found to be significant in other studies, neither soil pH, Ca nor Al was related to nitrification. Results showed a strong relationship between dominant vegetation, soil C, and soil C/N. ?? 2008 Springer Science+Business Media, LLC.

  1. Microscale Distribution of Nitrification Activity in Sediment Determined with a Shielded Microsensor for Nitrate

    OpenAIRE

    Jensen, Kim; Revsbech, Niels Peter; Nielsen, Lars Peter

    1993-01-01

    Microprofiles of O2 and NO3- were measured simultaneously in freshwater sediment with microsensors which were completely free from electrical interference because of coaxial designs. Depth profiles of nitrification (NO3- production) and denitrification (NO3- consumption) were subsequently determined by computer simulation of the measured microprofiles. The nitrifying bacterial community responded very quickly to changes in environmental conditions, and new steady-state microprofiles of O2 and...

  2. Autotrophic Ammonia-Oxidizing Bacteria Contribute Minimally to Nitrification in a Nitrogen-Impacted Forested Ecosystem

    OpenAIRE

    Jordan, F L; Cantera, JJL; Fenn, M E; Stein, L.Y.

    2005-01-01

    Deposition rates of atmospheric nitrogenous pollutants to forests in the San Bernardino Mountains range east of Los Angeles, California, are the highest reported in North America. Acidic soils from the west end of the range are N-saturated and have elevated rates of N-mineralization, nitrification, and nitrate leaching. We assessed the impact of this heavy nitrogen load on autotrophic ammonia-oxidizing communities by investigating their composition, abundance, and activity. Analysis of 177 cl...

  3. Revisiting nitrification in the Eastern Tropical South Pacific: A focus on controls

    Science.gov (United States)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Warner, Mark J.; Devol, Allan H.; Ward, Bess B.

    2016-03-01

    Nitrification, the oxidation of ammonium (NH4+) to nitrite (NO2-) and to nitrate (NO3-), is a component of the nitrogen (N) cycle internal to the fixed N pool. In oxygen minimum zones (OMZs), which are hotspots for oceanic fixed N loss, nitrification plays a key role because it directly supplies substrates for denitrification and anaerobic ammonia oxidation (anammox), and may compete for substrates with these same processes. However, the control of oxygen and substrate concentrations on nitrification are not well understood. We performed onboard incubations with 15N-labeled substrates to measure rates of NH4+ and NO2- oxidation in the eastern tropical South Pacific (ETSP). The spatial and depth distributions of NH4+ and NO2- oxidation rates were primarily controlled by NH4+ and NO2- availability, oxygen concentration, and light. In the euphotic zone, nitrification was partially photoinhibited. In the anoxic layer, NH4+ oxidation was negligible or below detection, but high rates of NO2- oxidation were observed. NH4+ oxidation displayed extremely high affinity for both NH4+ and oxygen. The positive linear correlations between NH4+ oxidation rates and in situ NH4+ concentrations and ammonia monooxygenase subunit A (amoA) gene abundances in the upper oxycline indicate that the natural assemblage of ammonia oxidizers responds to in situNH4+ concentrations or supply by adjusting their population size, which determines the NH4+ oxidation potential. The depth distribution of archaeal and bacterial amoA gene abundances and N2O concentration, along with independently reported simultaneous direct N2O production rate measurements, suggests that AOA were predominantly responsible for NH4+ oxidation, which was a major source of N2O production at oxygen concentrations > 5 µM.

  4. Aquarium Nitrification Revisited: Thaumarchaeota Are the Dominant Ammonia Oxidizers in Freshwater Aquarium Biofilters

    OpenAIRE

    Sauder, Laura A; Katja Engel; Stearns, Jennifer C; Masella, Andre P; Richard Pawliszyn; Neufeld, Josh D.

    2011-01-01

    Ammonia-oxidizing archaea (AOA) outnumber ammonia-oxidizing bacteria (AOB) in many terrestrial and aquatic environments. Although nitrification is the primary function of aquarium biofilters, very few studies have investigated the microorganisms responsible for this process in aquaria. This study used quantitative real-time PCR (qPCR) to quantify the ammonia monooxygenase (amoA) and 16S rRNA genes of Bacteria and Thaumarchaeota in freshwater aquarium biofilters, in addition to assessing the d...

  5. The evaluation of metham sodium and dichlobenil impacts on activated sludge nitrification

    OpenAIRE

    Ake, Timothy Nelson

    1995-01-01

    Sanafoam Vaporooter II is a trademark name for a process which uses metham sodium and dichlobenil to remove tree roots from municipal sewer and storm drain lines. One or more of the chemicals in this process, or their degradation products, have been suspected of disrupting the nitrification process in waste treatment plants downstream of the points of application. This work was undertaken to identify the chemical responsible for the disruption, and to recommend means f...

  6. Seasonal dynamics of soil respiration and nitrification in three subtropical plantations in southern China

    OpenAIRE

    Wang W; Cheng R; Shi Z; Ingwersen J; Luo D; Liu S

    2016-01-01

    Numerous studies have documented that soil respiration and nitrogen cycling show a distinct seasonal dependence regulated by environmental factors (e.g., soil temperature and soil water content). The mechanisms controlling the seasonal dependence of these two key ecosystem processes have rarely been linked to both soil microbial community and soil environmental factors. Here, we present results on the seasonal patterns of soil respiration and gross nitrification rates in three subtropical pla...

  7. Studies on the impact of food web effects on nitrification in aquatic sediments

    OpenAIRE

    Prast, Mario

    2007-01-01

    Nitrification is an important biogeochemical pathway in the upper, oxic layer of aquatic sediments and is predominantly accomplished by two groups of chemolithotrophic nitrifying bacteria. While these bacteria have been subject to numerous autecological studies before, they have rarely been regarded as part of food webs, in which they have to compete with other organisms for nutrients and substrates and in which they are prey to other organisms. The impact of ciliates as important bacterial g...

  8. An assessment of nitrification inhibitors to reduce nitrous oxide emissions from UK agriculture

    International Nuclear Information System (INIS)

    A trial was conducted consisting of 14 experiments across sites in England of contrasting soil type and annual rainfall to assess the effectiveness of nitrification inhibitors (predominantly dicyandiamide (DCD) but limited assessment also of 3, 4-dimethylpyrazole phosphate (DMPP) and a commercial product containing two pyrazole derivatives) in reducing direct nitrous oxide (N2O) emissions from fertilizer nitrogen (N), cattle urine and cattle slurry applications to land. Measurements were also made of the impact on ammonia (NH3) volatilization, nitrate (NO3−) leaching, crop yield and crop N offtake. DCD proved to be very effective in reducing direct N2O emissions following fertilizer and cattle urine applications, with mean reduction efficiencies of 39, 69 and 70% for ammonium nitrate, urea and cattle urine, respectively. When included with cattle slurry a mean, non-significant reduction of 56% was observed. There were no N2O emission reductions observed from the limited assessments of the other nitrification inhibitors. Generally, there were no impacts of the nitrification inhibitors on NH3 volatilization, NO3− leaching, crop yield or crop N offtake. Use of DCD could give up to 20% reduction in N2O emissions from UK agriculture, but cost-effective delivery mechanisms are required to encourage adoption by the sector. Direct N2O emissions from the studied sources were substantially lower than IPCC default values and development of UK country-specific emission factors for use in inventory compilation is warranted. (paper)

  9. Simultaneous heterotrophic nitrification and aerobic denitrification by the marine origin bacterium Pseudomonas sp. ADN-42.

    Science.gov (United States)

    Jin, Ruofei; Liu, Tianqi; Liu, Guangfei; Zhou, Jiti; Huang, Jianyu; Wang, Aijie

    2015-02-01

    Recent research has highlighted the existence of some bacteria that are capable of performing heterotrophic nitrification and have a phenomenal ability to denitrify their nitrification products under aerobic conditions. A high-salinity-tolerant strain ADN-42 was isolated from Hymeniacidon perleve and found to display high heterotrophic ammonium removal capability. This strain was identified as Pseudomonas sp. via 16S rRNA gene sequence analysis. Gene cloning and sequencing analysis indicated that the bacterial genome contains N2O reductase function (nosZ) gene. NH3-N removal rate of ADN-42 was very high. And the highest removal rate was 6.52 mg/L · h in the presence of 40 g/L NaCl. Under the condition of pure oxygen (DO >8 mg/L), NH3-N removal efficiency was 56.9 %. Moreover, 38.4 % of oxygen remained in the upper gas space during 72 h without greenhouse gas N2O production. Keeping continuous and low level of dissolved oxygen (DO <3 mg/L) was helpful for better denitrification performance. All these results indicated that the strain has heterotrophic nitrification and aerobic denitrification abilities, which guarantee future application in wastewater treatment. PMID:25432342

  10. Enhanced aerobic granulation, stabilization, and nitrification in a continuous-flow bioreactor by inoculating biofilms.

    Science.gov (United States)

    Yang, Yang; Zhou, Dandan; Xu, Zhengxue; Li, Aijun; Gao, Hang; Hou, Dianxun

    2014-06-01

    In this study, the possibility of using backwashed biofilm as seed in an aerobic granular sludge continuous-flow airlift fluidized bed (CAFB) reactor was investigated. After the addition of the inoculated backwashed biofilm, the start-up period of this reactor fed with municipal wastewater was reduced to 25 days, and aerobic granulation and stabilization were enhanced. At steady state, the chemical oxygen demand (COD) removal efficiency and nitrification efficiency were as high as 80-90 and 60 %, respectively. The CAFB was operated continuously and totally for 90 days, and its performance was much more stable when compared with system inoculated with activated sludge. Microbial distribution analyzed by fluorescence in situ hybridization (FISH) showed that the nitrite-oxidizing bacteria (NOB) and ammonium-oxidizing bacteria (AOB) were compatible with heterotrophic bacteria and distributed evenly throughout the granules. Such unique population distribution might be attributed to the low COD level and abundant dissolved oxygen in the entire granule as simulated by the mathematic models. Moreover, scanning electron microscopy revealed broad holes in the granules, which might promote the mass transfer of the nutrients from the surface to the center and enable simultaneous COD removal and nitrification. In conclusion, backwashed biofilm is an alternative seed of the conventional flocculent activated sludge in the aerobic granular sludge system to enhance carbonaceous oxidization and nitrification. PMID:24643735

  11. Occurrence of nitrifying bacteria and nitrification in Finnish drinking water distribution systems.

    Science.gov (United States)

    Lipponen, Mari T T; Suutari, Merja H; Martikainen, Pertti J

    2002-10-01

    Microbiological nitrification process may lead to chemical, microbiological and technical problems in drinking water distribution systems. Nitrification activity is regulated by several physical, and chemical, and operational factors. However, the factors affecting nitrification in the distribution systems in boreal region, having its specific environmental characteristics, are poorly known. We studied the occurrence and activity of nitrifying bacteria in 15 drinking water networks distributing water with very different origin and treatment practices. The waters included chloraminated surface water, chlorinated surface water, and non-disinfected groundwater. The networks were located in eight towns in different parts of Finland. Our results showed that nitrifying bacteria are common in boreal drinking water distribution systems despite their low temperature. Surprisingly high numbers and activities of nitrifiers were detected in pipeline sediment samples. The numbers of ammonia-oxidizing bacteria and their oxidation potentials were highest in chloraminated drinking water delivering networks, whereas the nitrite-oxidizing bacteria were present in the greatest numbers in those networks that used non-disinfected groundwater. The occurrence of nitrifying bacteria in drinking water samples correlated positively with the numbers of heterotrophic bacteria and turbidity, and negatively with the content of total chlorine. Although nitrifying bacteria grew well in drinking water distribution systems, the problems with nitrite accumulation are rare in Finland. PMID:12420937

  12. Contribution of nitrification and denitrification to N2O emissions from urine patches

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann

    2007-01-01

    N(2)O loss ratio of nitrification (i.e. moles of N(2)O-N produced per moles of nitrate produced) and denitrification (i.e. moles of NO produced per moles of N(2)O + N(2) Produced). The effect of artificial urine (52.9 g N m(-2)) and ammonium solution (52.9g N m(-2)) was examined in separate...... experiments at 45% and 35% water-filled pore space (WFPS), respectively, and in each experiment a water control was included. The N(2)O loss derived from nitrification or denitrification was determined in the field immediately after application of (15)N-labelled solutions. During the next 24 h, gross...... nitrification rates were measured in the field, whereas the denitrification rates were measured in soil cores in the laboratory. Compared with the water control, urine application increased the N(2)O emission from 3.9 to 42.3 mu g N(2)O-N m(-2) h(-1), whereas application of ammonium increased the emission from...

  13. The effect of nitrification in the oxygen balance of the Upper Chattahoochee River, Georgia

    Science.gov (United States)

    Ehlke, Theodore A.

    1979-01-01

    Oxygen consumption as a result of nitrification, and carbonaceous bacterial oxidation were compared in a 108 kilometer reach of the Chattahoochee River, Georgia. Nitrogenous and carbonaceous oxygen consumption were separated by using an inhibitor of nitrification 1-allyl-2-thiourea. The comparison was conducted in the laboratory using samples collected from the water column. Nitrification accounted for 38 to 52 percent of the total oxygen consumption. Nitrifying bacteria were enumerated from the same reach of the river. The population of Nitrosomonas ranged from 10 to 1,000 per milliliter in the water column and 100 to 100,000 per gram of benthic sediment. The nitrobacter population ranged from 10 to 100 per milliliter in the water column and 100 to 1,000 per gram in the benthic sediment. The concentration of ammonium, nitrite, and nitrate as N was determined from water samples collected throughout the study reach. The average rate of ammonium disappearance and of nitrate appearance was 0.02 milligram per liter per hour of flow time. (Woodard-USGS)

  14. Conversion of Natural Ecosystems to Cropland Increases the Soil Net Nitrogen mineralization and Nitrification in Tibet

    Institute of Scientific and Technical Information of China (English)

    YANG Li-Lin; ZHANG Fu-Suo; MAO Ren-Zhao; JU Xiao-Tang; Cai Xiao-Bu; LI Ya-Hai

    2008-01-01

    A comparative study was conducted to determine the NH+4 and NO-3 concentrations in soil profiles and to examine the net itrogen (N) mineralization and nitrification in adjacent forest, grassland, and cropland soils on the Tibetan Plateau. Cropland soil showed significantly higher inorganic N concentrations in soil profiles compared with forest and grassland soils. NO-3-Naccounted for 70%-90% of inorganic N in cropland soil, while NH+4-N was the main form of inorganic N in forest and grassland soils. The average net N mineralization rate at 0-20 cm depth was approximately twice in cropland soil (1.48 mg kg-1 d-1) as high as in forest (0.83 mg kg-1 d-1) or grassland soil (0.72 mg kg-1 d-1). Cropland showed strong net nitrification, with the net rate almost equal to the total net N mineralization. Urea addition stimulated soil respiration, particularly in forest oil. Most urea-N, however, remained as NH+4 in forest and grassland soils, while NO-3 was the main form of inorganic N to increase n cropland soil. Higher rates of net nitrification in cropland soils suggest that land use change on the Tibetan Plateau may lead to high N losses through nitrate leaching.

  15. Factors affecting simultaneous nitrification and denitrification in an SBBR treating domestic wastewater

    Institute of Scientific and Technical Information of China (English)

    LI Jun; PENG Yongzhen; GU Guowei; WEI Su

    2007-01-01

    An aerobic sequencing batch biofilm reactor(SBBR)packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification.The SBBR is advantageous for creating an anoxic condition,and the biofilm can absorb and store carbon for good nitrification and denitrification.An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification.Volumetric loads of TN dropped dramatically and effiueut TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L.The efficiency of simultaneous nitritication and denitrification(SND)increased with increasing thickness of the biofilm.The influent concentration hardly affected the TN removal efficiency,but the effluent TN increased with increasing influent concentration.It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements.At optimum operating parameters,the TN removal efficiency of 74%-82% could be achieved.

  16. Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone

    Science.gov (United States)

    Ji, Qixing; Babbin, Andrew R.; Jayakumar, Amal; Oleynik, Sergey; Ward, Bess B.

    2015-12-01

    The Eastern Tropical South Pacific oxygen minimum zone (ETSP-OMZ) is a site of intense nitrous oxide (N2O) flux to the atmosphere. This flux results from production of N2O by nitrification and denitrification, but the contribution of the two processes is unknown. The rates of these pathways and their distributions were measured directly using 15N tracers. The highest N2O production rates occurred at the depth of peak N2O concentrations at the oxic-anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N2O production from both nitrification and denitrification and (2) higher nitrous oxide production yields from nitrification. Within the ODZ proper (i.e., anoxia), the only source of N2O was denitrification (i.e., nitrite and nitrate reduction), the rates of which were reflected in the abundance of nirS genes (encoding nitrite reductase). Overall, denitrification was the dominant pathway contributing the N2O production in the ETSP-OMZ.

  17. Effect of organic carbon on nitrification efficiency and community composition of nitrifying biofilms

    Institute of Scientific and Technical Information of China (English)

    HU Jie; LI Daping; LIU Qiang; TAO Yong; HE Xiaohong; WANG Xiaomei; LI Xudong; GAO Ping

    2009-01-01

    The effects of organic carbon/inorganic nitrogen (C/N) ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (DGGE) analysis. The results showed that the nitrification rate decreased with an increasing organic concentration. However, the effect became weak when the carbon concentration reached sufficiently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8 and 16 compare to control (C/N = 0). The loss of nitrogen at C/N = 0.5, 1, 2, 4, (8 and 16 was 31%, 18%, 24%, 65%, 59% and 62% respectively, after 24 h. Sequence analysis of 16S rRNA gene fragments revealed that the dominant populations changed from nitrifying bacteria (Nitrosomonas europaea and Nitrobacter sp.) to denitrifying bacteria (Pseudomonas sp., Acidovorax sp. and Comamonas sp.) with C/N ratio increase. Although at high C/N ratio the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Conrrespondingly, nitrification process coexisted with denitrification.

  18. Imbalance between vertical nitrate flux and nitrate assimilation on a continental shelf: Implications of nitrification

    Science.gov (United States)

    Shiozaki, Takuhei; Furuya, Ken; Kurotori, Hiroyuki; Kodama, Taketoshi; Takeda, Shigenobu; Endoh, Takahiro; Yoshikawa, Yutaka; Ishizaka, Joji; Matsuno, Takeshi

    2011-10-01

    The nitrate assimilation rate and diapycnal nitrate flux were simultaneously determined on the continental shelf of the East China Sea (ECS). Further, the archaeal amoA gene was quantified to examine the potential distribution of nitrification activity. Nitrate assimilation rates and distribution of the archaeal amoA gene were also investigated in the Philippine Sea and in the Kuroshio Current. At all the stations, while the surface nitrate was depleted (amoA was observed at shallower light depths, namely at or above 10% light depth, in the ECS than in other regions, suggesting that nitrification occurred within the euphotic zone in the ECS, especially on the shelf. Moreover, a station on the continental shelf of the ECS exhibited a considerable discrepancy between the nitrate assimilation rate (1500 μmolN m-2 d-1) and vertical nitrate flux (98 μmolN m-2 d-1). Here, 6.7 ± 3.1 × 103 and 2.5 ± 0.7 × 105 copies mL-1 of archaeal amoA were detected at 10% and 1% light depths relative to the surface, respectively. Thus nitrification within the euphotic zone would be attributed at least in part to the observed discrepancy between nitrate assimilation and vertical flux. These observations imply that the assumption of a direct relationship between new production, export production, and measured nitrate assimilation is misplaced, particularly regarding the continental shelf of the ECS.

  19. Nitrous oxide formation during nitritation and nitrification of high-strength wastewater.

    Science.gov (United States)

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl-Heinz

    2013-01-01

    The purpose of this study was to investigate the formation of nitrous oxide (N2O) in nitritation and nitrification under stable, comparable and not limiting conditions typical for treatment of high-strength wastewater. A laboratory-scale aerated chemostat was operated with reject water at different sludge retention times, achieving suppression of nitrate formation by wash-out of nitrite-oxidizing bacteria for nitritation. The N2O formation factor during stable nitritation was higher (2.90% N2O-N /NH4(-)-Nox) than during nitrification (0.74%). The positive correlation of N2O formation rates and ammonium oxidation rates was linear and thus did not contribute to changes of the N2O formation factor. The dominant factor for N2O formation during stable operation was high nitrite concentration, which was positively correlated with N2O formation rates. The highest formation factors were observed during a transition phase from nitrification to nitritation with unstable process conditions (4.81%) and during a short-term experiment with increased pH of 7 (10.28%). The results indicate that even with operational conditions that are regarded favourable for the process of nitritation N2O formation can be limited but not avoided. PMID:23752381

  20. One-day rate measurements for estimating net nitrification potential in humid forest soils

    Science.gov (United States)

    Ross, D.S.; Fredriksen, G.; Jamison, A.E.; Wemple, B.C.; Bailey, S.W.; Shanley, J.B.; Lawrence, G.B.

    2006-01-01

    Measurements of net nitrification rates in forest soils have usually been performed by extended sample incubation (2-8 weeks), either in the field or in the lab. Because of disturbance effects, these measurements are only estimates of nitrification potential and shorter incubations may suffice. In three separate studies of northeastern USA forest soil surface horizons, we found that laboratory nitrification rates measured over 1 day related well to those measured over 4 weeks. Soil samples of Oa or A horizons were mixed by hand and the initial extraction of subsamples, using 2 mol L-1 KCl, occurred in the field as soon as feasible after sampling. Soils were kept near field temperature and subsampled again the following day in the laboratory. Rates measured by this method were about three times higher than the 4-week rates. Variability in measured rates was similar over either incubation period. Because NO3- concentrations were usually quite low in the field, average rates from 10 research watersheds could be estimated with only a single, 1-day extraction. Methodological studies showed that the concentration of NH4+ increased slowly during contact time with the KCl extractant and, thus, this contact time should be kept similar during the procedure. This method allows a large number of samples to be rapidly assessed. ?? 2006 Elsevier B.V. All rights reserved.

  1. Quick Start-up and Sustaining of Shortcut Nitrification in Continuous Flow Reactor%连续流反应器短程硝化的快速启动与维持机制

    Institute of Scientific and Technical Information of China (English)

    吴鹏; 张诗颖; 宋吟玲; 徐乐中; 沈耀良

    2016-01-01

    如何快速稳定地启动短程硝化工艺对低C/N比废水的处理具有十分重要的实际应用价值。针对城市污水厂以连续流工艺为主的现状,故对连续流反应器短程硝化的快速启动与维持进行研究。结果表明,利用间歇曝气,依次控制3个阶段的停/曝时间(15 min/45 min、45 min/45 min和30 min/30 min),连续流反应器经过60 d左右的运行,可以成功实现短程硝化的快速启动。控制停/曝时间为30 min/30 min,进水氨氮浓度为50或100 mg•L-1时,亚硝化率分别可达90%或95%。另外,间歇曝气有利于抑制硝化菌( NOB)的活性,而缩短水力停留时间( HRT)可淘洗出NOB,两者结合可以更好地维持短程硝化。%How to achieve fast and stable startup of shortcut nitrification has a very important practical value for treatment of low C/N ratio wastewater. Thus, the quick start-up and sustaining of shortcut nitrification were investigated in continuous flow reactor targeting at the current situation of urban wastewater treatment plant using a continuous flow process. The results showed that quick start-up of shortcut nitrification could be successfully achieved in a continuous flow reactor after 60 days’ operation with intermittent aeration and controlling of three stages of stop/aeration time (15 min/45 min, 45 min/45 min and 30 min/30 min). The nitrification rates could reach 90% or 95% respectively, while influent ammonia concentrations were 50 or 100 mg•L-1 with stop/aeration time of 30 min/30 min. In addition, intermittent aeration could inhibit the activity of nitrite oxidizing bacteria (NOB), while short hydraulic retention time ( HRT) may wash out NOB. And a combined use of both measures was beneficial to sustain shortcut nitrification.

  2. Inhibition of Nitrifiers and Methanotrophs from an Agricultural Humisol by Allylsulfide and Its Implications for Environmental Studies

    OpenAIRE

    Neufeld, Josh D.; Knowles, Roger

    1999-01-01

    Allylsulfide, an inhibitor of ammonia monooxygenase, was tested to determine its ability to inhibit nitrification and methane oxidation in pure cultures, in agricultural humisol enrichment cultures, and in humisol slurries. We confirmed that allylsulfide is a differential inhibitor of cultures of nitrifiers and methanotrophs at concentrations of 1 and 200 μM, respectively, which result in 50% inhibition. However, although a nitrifying enrichment culture added to sterilized humisol was inhibit...

  3. Fate of nanosilver in wastewater treatment plants and their impact on nitrification activity in sewage sludge; Verhalten von Nanosilber in Klaeranlagen und dessen Einfluss auf die Nitrifikationsleistung in Belebtschlamm

    Energy Technology Data Exchange (ETDEWEB)

    Burkhardt, Michael [Eawag: Das Wasserforschungs-Institut des ETH-Bereichs, Duebendorf (Switzerland); HSR Hochschule fuer Technik, Rapperswil (CH). Inst. fuer Umwelt- und Verfahrenstechnik (UMTEC); Zuleeg, Steffen [Eawag: Das Wasserforschungs-Institut des ETH-Bereichs, Duebendorf (Switzerland); KUSTER + HAGER Ingenieurbuero AG, St. Gallen (Switzerland); Kaegi, Ralf; Sinnet, Brian; Eugster, Jakob; Boller, Markus; Siegrist, Hansruedi [Eawag: Das Wasserforschungs-Institut des ETH-Bereichs, Duebendorf (Switzerland)

    2010-10-15

    %). The mass fluxes are similar to metallic colloidal nanosilver investigated under the same conditions. The mass balance has been consistently confirmed by the full-scale study in a municipal wastewater treatment plant. The silver fluxes correspond to the fluxes of the suspended solids in sludge and effluent. Overall, it is estimated that from public wastewater treatment plants about 4-40 mg/a Ag per inhabitant equivalent are discharged annually to the receiving water. The analysis by SEM-EDX demonstrates adsorption and incorporation of nanosilver on biological flocs. This method yields first insight into complex building and transformation of silver associated with sulfide after adding metallic nanosilver and silver chloride to wastewater. Silver ions released from nanosilver react immediately with large amounts of chloride present in wastewater to form silver chloride. Silver ions may react with organic ligands or sulfide groups additionally. Consequently, even silver nitrate added with 1 mg/L Ag (250 mg Ag/kg TS) to activated sludge did not inhibit nitrification activity. Very high amounts of nanosilver, i. e. 100 mg/L Ag, overburdened the system and equilibrium condition between silver ion release and ligands was not reached. The mass balance reflects the excellent attachment of nanosilver to activated sludge and biological flocs. Therefore, the main elimination process of nanosilver is attachment to the activated sludge. The elimination of nanosilver is high compared to organic and inorganic micro pollutants omnipresent in wastewater. Any further reduction of suspended solids in the effluent water will reduce the silver load. Generally, in wastewater nanosilver occurs bonded to activated sludge flocs and therefore the elimination of nanosilver is efficient under operation conditions typical for wastewater treatment plants. The major fraction of nanosilver is removed from the system by the excess sludge withdrawal. Nonetheless, the efficiency may be further improved

  4. Organic carbon and iron modulate nitrification rates in mangrove swamps of Goa, south west coast of India

    Science.gov (United States)

    Krishnan, K. P.; Loka Bharathi, P. A.

    2009-09-01

    Nitrification, fuelled by ammonium is the pivotal oxidative pathway to nitrogen cycling. In spite of its ecological significance, the factors regulating nitrification rates in the benthic realm remain poorly understood. The present study therefore examines some of the factors like ammonium, nitrite, nitrate, organic carbon, iron and manganese on down-core variability in benthic nitrification rates in two different mangrove ecosystems, one under the influence of ferromanganese ore mining (experiment) and the other relatively undisturbed (control). We hypothesize that besides organic carbon, iron could also influence the rate of nitrification. The study also contrasts the distributive pattern of autotrophic and heterotrophic nitrifiers in the two regions. The concentration of iron at the control site ranged from 1.1% to 15.1% while at the experimental site it ranged from 2.9% to 46%. The levels of organic carbon at control and experimental sites ranged from 0.02% to 6.9% and 0.1% to 6.5%, respectively. The nitrification rates at the control and experimental sites are comparable and ranged from 3.2 ± 1.2 to 18.4 ± 1.9 ng at-N g(sediment) -1 h -1 and 2.7 ± 1.5 to 18.2 ± 0.6 ng at-N g(sediment) -1 h -1, respectively. While the abundance of heterotrophic nitrifiers at both the sites ranged from 10 2-3 cells g -1 sediment, the autotrophic nitrifiers at the experimental site was higher by an order at ˜10 3 cells g -1 sediment reflecting the relatively higher refractile nature of organic carbon at the experimental site (Straus and Lamberti, 2000). Though organic carbon and nitrification rates are similar in both the sites, the underlying mechanisms governing the processes could be different. Our studies suggest that at the control site, heterotrophic nitrifiers govern nitrification rates ( r = 0.28, p < 0.05, n = 64) using organic carbon ( r = 0.32, p < 0.01, n = 64). At the experimental site, nitrification was governed more by autotrophic nitrifiers ( r = 0.43, p < 0

  5. Effect of irrigation, nitrogen application, and a nitrification inhibitor on nitrous oxide, carbon dioxide and methane emissions from an olive (Olea europaea L.) orchard.

    Science.gov (United States)

    Maris, S C; Teira-Esmatges, M R; Arbonés, A; Rufat, J

    2015-12-15

    Drip irrigation combined with nitrogen (N) fertigation is applied in order to save water and improve nutrient efficiency. Nitrification inhibitors reduce greenhouse gas emissions. A field study was conducted to compare the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) associated with the application of N fertiliser through fertigation (0 and 50kgNha(-1)), and 50kgNha(-1)+nitrification inhibitor in a high tree density Arbequina olive orchard. Spanish Arbequina is the most suited variety for super intensive olive groves. This system allows reducing production costs and increases crop yield. Moreover its oil has excellent sensorial features. Subsurface drip irrigation markedly reduced N2O and N2O+N2 emissions compared with surface drip irrigation. Fertiliser application significantly increased N2O+N2, but not N2O emissions. Denitrification was the main source of N2O. The N2O losses (calculated as emission factor) ranging from -0.03 to 0.14% of the N applied, were lower than the IPCC (2007) values. The N2O+N2 losses were the largest, equivalent to 1.80% of the N applied, from the 50kgNha(-1)+drip irrigation treatment which resulted in water filled pore space >60% most of the time (high moisture). Nitrogen fertilisation significantly reduced CO2 emissions in 2011, but only for the subsurface drip irrigation strategies in 2012. The olive orchard acted as a net CH4 sink for all the treatments. Applying a nitrification inhibitor (DMPP), the cumulative N2O and N2O+N2 emissions were significantly reduced with respect to the control. The DMPP also inhibited CO2 emissions and significantly increased CH4 oxidation. Considering global warming potential, greenhouse gas intensity, cumulative N2O emissions and oil production, it can be concluded that applying DMPP with 50kgNha(-1)+drip irrigation treatment was the best option combining productivity with keeping greenhouse gas emissions under control. PMID:26367066

  6. Use of dissolved inorganic carbon isotopes to track photosynthesis, respiration, and nitrification along a 56 mile transect in the Sacramento River and San Francisco Bay

    Science.gov (United States)

    Silva, S. R.; Kendall, C.; Peek, S.; Young, M. B.

    2013-12-01

    A decline in phytoplankton stocks in the San Francisco Bay and Delta is thought to contribute to the pelagic organism decline observed over the past two decades. One factor controlling phytoplankton growth rate is the availability of nutrients. Although there is an excess of nutrients in the Bay and Delta, the type and relative abundance of nutrients is critical to phytoplankton growth. To evaluate the response of phytoplankton to nutrient sources and to better understand phytoplankton dynamics downstream, we tested the hypothesis that the δ13C values of dissolved inorganic carbon (DIC) along with conventional water chemistry analyses will record events such as increased nitrification (related to the Sacramento River Wastewater Treatment Plant ammonium input) and algal blooms, and reflect the balance between photosynthesis and bacterial respiration. Multiple parameters affect [DIC] and its δ13C, including DIC sources, pH, and biological processes. Consumption of CO2 by phytoplankton during photosynthesis and by autotrophic bacteria during nitrification both result in increases in δ13C-DIC. However, photosynthesis and nitrification have very different relationships to chlorophyll and nutrient concentrations. The balance between heterotrophic bacterial respiration and photosynthesis should be reflected in trends in DIC, nutrient, and chlorophyll concentration, and δ13C-DIC. The δ13C of DIC should also be reflected in the δ13C of phytoplankton with approximately a 20 per mil fractionation. Significant deviation in the fractionation factor may indicate local variations in growth rate, nutrient availability, or speciation. Combined, these parameters should provide a gauge of the relative importance of the above mentioned processes. To test this hypothesis, we collected 19 water samples per cruise between July 2012 and July 2013 along a 56 mile transect between Rio Vista on the Sacramento River and San Francisco Bay near Angel Island during 8 cruises on the USGS RV

  7. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification.

    Science.gov (United States)

    Braeckman, Ulrike; Van Colen, Carl; Guilini, Katja; Van Gansbeke, Dirk; Soetaert, Karline; Vincx, Magda; Vanaverbeke, Jan

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable and fine sandy sediments under pre-phytoplankton bloom and bloom conditions. Ocean acidification, as mimicked in the laboratory by a realistic pH decrease of 0.3, significantly reduced SCOC on average by 60% and benthic nitrification rates on average by 94% in both sediment types in February (pre-bloom period), but not in April (bloom period). No changes in macrofauna functional community (density, structural and functional diversity) were observed between ambient and acidified conditions, suggesting that changes in benthic biogeochemical cycling were predominantly mediated by changes in the activity of the microbial community during the short-term incubations (14 days), rather than by changes in engineering effects of bioturbating and bio-irrigating macrofauna. As benthic nitrification makes up the gross of ocean nitrification, a slowdown of this nitrogen cycling pathway in both permeable and fine sediments in winter, could therefore have global impacts on coupled nitrification-denitrification and hence eventually on pelagic nutrient availability. PMID:25329898

  8. Archaeal Ammonia Oxidizers Dominate in Numbers, but Bacteria Drive Gross Nitrification in N-amended Grassland Soil

    Science.gov (United States)

    Sterngren, Anna E.; Hallin, Sara; Bengtson, Per

    2015-01-01

    Both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) play an important role in nitrification in terrestrial environments. Most often AOA outnumber AOB, but the relative contribution of AOA and AOB to nitrification rates remains unclear. The aim of this experiment was to test the hypotheses that high nitrogen availability would favor AOB and result in high gross nitrification rates, while high carbon availability would result in low nitrogen concentrations that favor the activity of AOA. The hypotheses were tested in a microcosm experiment where sugars, ammonium, or amino acids were added regularly to a grassland soil for a period of 33 days. The abundance of amoA genes from AOB increased markedly in treatments that received nitrogen, suggesting that AOB were the main ammonia oxidizers here. However, AOB could not account for the entire ammonia oxidation activity observed in treatments where the soil was deficient in available nitrogen. The findings suggest that AOA are important drivers of nitrification under nitrogen-poor conditions, but that input of easily available nitrogen results in increased abundance, activity, and relative importance of AOB for gross nitrification in grassland soil. PMID:26648926

  9. Effects of Different Concentrations of Ammonia Nitrogen on N2O Emission in the Process of Partial Nitrification

    Institute of Scientific and Technical Information of China (English)

    TIAN; Lin; KONG; Qiang; ZHANG; Jian; MIAO; Ming-sheng

    2012-01-01

    [Objective] The study aimed to discuss the effects of different concentrations of ammonia nitrogen on N2O emission in the process of partial nitrification. [Method] By using a sequencing batch biofilm reactor (SBBR) under intermittent aeration, the influences of various concentrations of influent ammonia nitrogen on nitrous oxide (N2O) emission from partial nitrification were analyzed. [Result] When the concentration of influent ammonia nitrogen varied from 200 to 400 mg/L, the changing trends of DO and ORP value were consistent during the process of partial nitrification, and the concentration ratio of NO-2-N to NH+4-N in effluent water reached 1∶1, with lower NO-3-N level. In addition, ammonia nitrogen concentration in the influent had significant effects on N2O emission in the process of partial nitrification, that is, the higher the ammonia nitrogen concentration, the more the N2O emission. When ammonia nitrogen concentration was 400 mg/L, N2O emission was up to about 37 mg. [Conclusion] N2O emission in the process of partial nitrification might be related to the concentrations of NH+4 and NO-2.

  10. Effects of Different Concentrations of Ammonia Nitrogen on N_2O Emission in the Process of Partial Nitrification

    Institute of Scientific and Technical Information of China (English)

    TIAN; Lin; KONG; Qiang; ZHANG; Jian; MIAO; Ming-sheng

    2012-01-01

    [Objective] The study aimed to discuss the effects of different concentrations of ammonia nitrogen on N2O emission in the process of partial nitrification. [Method] By using a sequencing batch biofilm reactor (SBBR) under intermittent aeration, the influences of various concentrations of influent ammonia nitrogen on nitrous oxide (N2O) emission from partial nitrification were analyzed. [Result] When the concentration of influent ammonia nitrogen varied from 200 to 400 mg/L, the changing trends of DO and ORP value were consistent during the process of partial nitrification, and the concentration ratio of NO-2-N to NH+4-N in effluent water reached 1∶1, with lower NO-3-N level. In addition, ammonia nitrogen concentration in the influent had significant effects on N2O emission in the process of partial nitrification, that is, the higher the ammonia nitrogen concentration, the more the N2O emission. When ammonia nitrogen concentration was 400 mg/L, N2O emission was up to about 37 mg. [Conclusion] N2O emission in the process of partial nitrification might be related to the concentrations of NH+4 and NO-2.

  11. 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.

  12. CARBONACEOUS, NITROGENOUS AND PHOSPHORUS MATTERS REMOVAL FROM DOMESTIC WASTEWATER BY AN ACTIVATED SLUDGE REACTOR OF NITRIFICATION-DENITRIFICATION TYPE

    Directory of Open Access Journals (Sweden)

    MOHAMAD ALI FULAZZAKY

    2009-03-01

    Full Text Available This paper proposes an environmental engineering method based on biotechnology approach as one of the expected solutions that should be considered to implementing the activated sludge for improving the quality of water and living environment, especially to remove the major pollutant elements of domestic wastewater. Elimination of 3 major pollutant elements, i.e., carbon, nitrogen and phosphor containing the domestic wastewater is proposed to carry out biological method of an anoxic-aerobic reactor therein these types of pollutants should be consecutively processed in three steps. Firstly, eliminate the carbonaceous matter in the aerobic reactor. Secondly, to remove the carbonaceous and nitrogenous matters, it is necessary to modify the reactor’s nature from the aerobic condition to an anoxic-aerobic reactor. And finally, when the cycle of nitrification-denitrification is stable to achieve the target’s efficiency of reactor by adding the ferric iron into the activated sludge, it can be continued to remove the carbonaceous, nitrogenous and phosphorous matters simultaneously. The efficiency of carbonaceous and nitrogenous matters removal was confirmed with the effluent standard, COD is less than 100 mgO2/L and the value of global nitrogen is less than 10 mgN/L. The effectiveness of suspended matter removal is higher than 90% and the decantation of activated sludge is very good as identifying the Molhman’s index is below of 120 mL/L. The total phosphorus matter removal is more effective than the soluble phosphorus matter. By maintaining the reactor’s nature at the suitable condition, identifying the range of pH between 6.92 and 7.16 therefore the excellent abatement of phosphor of about 80% is achieving with the molar Fe/P ratio of 1.4.

  13. Enhancing nitrification at low temperature with zeolite in a mining operations retention pond

    Directory of Open Access Journals (Sweden)

    Misha eMiazga-Rodriguez

    2012-07-01

    Full Text Available Ammonium nitrate explosives are used in mining operations at Diavik Diamond Mines Inc. in the Northwest Territories, Canada. Residual nitrogen is washed into the mine pit and piped to a nearby retention pond where its removal is accomplished by microbial activity prior to a final water treatment step and release into the sub-Arctic lake, Lac de Gras. Microbial removal of ammonium in the retention pond is rapid during the brief ice-free summer, but often slows under ice cover that persists up to nine months of the year. The aluminosilicate mineral zeolite was tested as an additive to retention pond water to increase rates of ammonium removal at 4 °C. Water samples were collected across the length of the retention pond monthly over a year. The structure of the microbial community (bacteria, archaea, and eukarya, as determined by denaturing gradient gel electrophoresis of PCR-amplified small subunit ribosomal RNA genes, was more stable during cold months than during July-September, when there was a marked phytoplankton bloom. Of the ammonia-oxidizing community, only bacterial amoA genes were consistently detected. Zeolite (10 g was added to retention pond water (100 mL amended with 5 mM ammonium and incubated at 12 °C to encourage development of a nitrifying biofilm. The biofilm community was composed of different amoA phylotypes from those identified in gene clone libraries of native water samples. Zeolite biofilm was added to fresh water samples collected at different times of the year, resulting in a significant increase in laboratory measurements of potential nitrification activity at 4 °C. A significant positive correlation between the amount of zeolite biofilm and potential nitrification activity was observed; rates were unaffected in incubations containing 1-20 mM ammonium. Addition of zeolite to retention ponds in cold environments could effectively increase nitrification rates year round by concentrating active nitrifying biomass.

  14. 四环素对水体硝化作用的影响%Effect of tetracycline on nitrification of water body

    Institute of Scientific and Technical Information of China (English)

    王薇佳; 杜云峰; 张华; 金庭旭; 谢春; 张震; 韦艳

    2012-01-01

    Objective To know whether the tetracycline would affect nitrification of water body. Methods Water samples of a reservoir were collected and treated with different concentrations of tetracycline, 0 μg/L(blank), 10 μg/L, 100 μg/L and 1 000 μg/L, through adding in it respectively. All of the samples were cultured at 20 ℃, for 10 days. The daily change about ammonia nitrogen, nitrite nitrogen and nitrate nitrogen were detected. Results The concentration of ammonia nitrogen was higher in the tetracycline -treated groups compared with the blank group in the fifth and eighth days. Nitrite nitrogen concentration in the blank group was lower than those in the tetracycline-treated groups, while nitrate nitrogen concentration was lower in the latter from the eighth day. Conclusion Tetracycline can delay the peak value of the ammonia nitrogen and inhibit the nitrate nitrogen in some degree. However, inhibition of nitrite nitrogen is not found. Tetracycline can cause the inhibition of nitrification of water body.%目的 了解四环素对水体硝化作用的影响.方法 向某市湖泊水样中分别加入终浓度为0(空白对照)、10、100、1000 μg/L的四环素溶液,并置于20℃恒温培养箱中培养10d,逐日测定”三氮”浓度.结果 第5、8天各实验组氨氮浓度均高于空白对照组.从第8天开始,各实验组亚硝酸盐氮浓度高于空白对照组,而硝酸盐氮浓度低于空白对照组.结论 四环素对水中氨氮浓度达到峰值具有一定的延迟作用,对硝酸盐氮产生具有一定抑制作用,但未发现其对亚硝化过程的抑制.因而四环素对水体硝化作用具有一定的抑制作用.

  15. NITRIFICATION OF UREA AND ASSIMILATION OF NITRATE IN SATURATED SOILS UNDER AEROBIC CONDITIONS

    Directory of Open Access Journals (Sweden)

    A. E. Ghaly

    2013-01-01

    Full Text Available The aim of this study was to investigate nitrification activity of urea and the assimilation of nitrate in a well aerated soil using perfusion technique with addition of glucose as an energy and carbon source. In this study, urea was rapidly nitrified by the bacteria in the saturated soil but its course of transformation to NO3 was not linear. There was an initial increase in the concentration of nitrite during the nitrification experiment which indicated that the conversion of nitrite to nitrate was appreciably slower than the rate of conversion of urea to nitrite. The rate of conversion of NH4+ to NO2- was faster than the rate of conversion of NO2- to NO3- in the first 12 days and as a result the nitrate concentration reached 2.72 µg/ml on the 12th day. After day 12, the concentration of NH4+ in solution declined significantly and the rate of conversion of NO2- to NO3- became faster than the rate of conversion of NH4+ to NO2-. The concentration of NO2-N in the solution reached zero on the 23rd day. The nitrification curve has the character of a sigmoid curve whose midpoint, which representing the most rapid rate of nitrification, fell at the point of half conversion of urea to nitrite. The curve asymptotically approaches a nitrate value that represents 98% conversion of urea into nitrate. The rest of the urea (NH4 has presumably been synthesized into bacterial cells. The initial pH of the soil was 7.7 due to the presence of NH4 which decreased gradually due to the production of NO3 reaching 6.9 by day 23. A nitrate reduction was observed under aerobic conditions. Denitrification did not proceed according to the known fact that O2 prevents the denitrifying organisms from producing the enzyme responsible for the process. The alternative pathway for nitrate reduction could be by assimilatory reduction where nitrate was converted to ammonium and then to cells. The removal of nitrate and production of ammonium caused a rise in the pH. The

  16. Evaluation of the persistence of micropollutants through pure-oxygen activated sludge nitrification and denitrification

    Science.gov (United States)

    Levine, A.D.; Meyer, M.T.; Kish, G.

    2006-01-01

    The persistence of pharmaceuticals, hormones, and household and industrial chemicals through a pure-oxygen activated sludge, nitrification, denitrification wastewater treatment facility was evaluated. Of the 125 micropollutants that were tested in this study, 55 compounds were detected in the untreated wastewater, and 27 compounds were detected in the disinfected effluent. The persistent compounds included surfactants, fire-retardant chemicals, pesticides, fragrance compounds, hormones, and one pharmaceutical. Physical-chemical properties of micropollutants that affected partitioning onto wastewater solids included vapor pressure and octanol-water partition coefficients.

  17. Nitrification of archaeal ammonia oxidizers in acid soils is supported by hydrolysis of urea

    OpenAIRE

    Lu, Lu; Han, Wenyan; Zhang, Jinbo; Wu, Yucheng; Wang, Baozhan; Lin, Xiangui; Zhu, Jianguo; Cai, Zucong; Jia, Zhongjun

    2012-01-01

    The hydrolysis of urea as a source of ammonia has been proposed as a mechanism for the nitrification of ammonia-oxidizing bacteria (AOB) in acidic soil. The growth of Nitrososphaera viennensis on urea suggests that the ureolysis of ammonia-oxidizing archaea (AOA) might occur in natural environments. In this study, 15N isotope tracing indicates that ammonia oxidation occurred upon the addition of urea at a concentration similar to the in situ ammonium content of tea orchard soil (pH 3.75) and ...

  18. Nitrification rates in Arctic soils are associated with functionally distinct populations of ammonia-oxidizing archaea

    Science.gov (United States)

    Alves, Ricardo J. E.; Wanek, Wolfgang; Zappe, Anna; Richter, Andreas; Svenning, Mette M.; Schleper, Christa; Urich, Tim

    2014-05-01

    The functioning of Arctic soil ecosystems is crucially important for global climate, although basic knowledge regarding their biogeochemical processes is lacking. Nitrogen (N) is the major limiting nutrient in these environments, and therefore it is particularly important to gain a better understanding of the microbial populations catalyzing transformations that influence N bioavailability. However, microbial communities driving this process remain largely uncharacterized in Arctic soils, namely those catalyzing the rate-limiting step of ammonia (NH3) oxidation. Eleven Arctic soils from Svalbard were analyzed through a polyphasic approach, including determination of gross nitrification rates through a 15N pool dilution method, qualitative and quantitative analyses of ammonia-oxidizing archaea (AOA) and bacteria (AOB) populations based on the functional marker gene amoA (encoding the ammonia monooxygenase subunit A), and enrichment of AOA in laboratory cultures. AOA were the only NH3 oxidizers detected in five out of 11 soils, and outnumbered AOB by 1 to 3 orders of magnitude in most others. AOA showed a great overall phylogenetic diversity that was differentially distributed across soil ecosystems, and exhibited an uneven population composition that reflected the dominance of a single AOA phylotype in each population. Moreover, AOA populations showed a multifactorial association with the soil properties, which reflected an overall distribution associated with tundra type and with several physico-chemical parameters combined, namely pH and soil moisture and N contents (i.e., NO3- and dissolved organic N). Remarkably, the different gross in situ and potential nitrification rates between soils were associated with distinct AOA phylogenetic clades, suggesting differences in their nitrifying potential, both under the native NH3 conditions and as a response to higher NH3 availability. This was further supported by the selective enrichment of two AOA clades that exhibited

  19. Linking crenarchaeal and bacterial nitrification to anammox in the Black Sea

    OpenAIRE

    Lam, Phyllis; Jensen, Marlene M.; Lavik, Gaute; McGinnis, Daniel F.; Müller, Beat; Schubert, Carsten J.; Amann, Rudolf; Thamdrup, Bo; Kuypers, Marcel M. M.

    2007-01-01

    Active expression of putative ammonia monooxygenase gene subunit A (amoA) of marine group I Crenarchaeota has been detected in the Black Sea water column. It reached its maximum, as quantified by reverse-transcription quantitative PCR, exactly at the nitrate maximum or the nitrification zone modeled in the lower oxic zone. Crenarchaeal amoA expression could explain 74.5% of the nitrite variations in the lower oxic zone. In comparison, amoA expression by γ-proteobacterial ammonia-oxidizing bac...

  20. Factors Influencing the Nitrification Efficiency of Fluidized Bed Filters With a Plastic Bead Medium

    OpenAIRE

    Sandu, Simonel Ioan

    2000-01-01

    Nitrification performance of three, fluidized-bed filters was investigated. Each filter contained 10 L of plastic bead medium (near neutral specific gravity and 2-4 mm diameter and length) and was loaded under conditions of various flow rates and ammonia levels. Bead settled depth and biofilter diameter (12.7, 15.2 and 17.8 cm) were the factors differing among the filters. The experiments were conducted with three replicate recirculating systems. Each system included one of the three differen...

  1. Sediment Nitrification, Denitrification, and Nitrous Oxide Production in a Deep Arctic Lake †

    OpenAIRE

    Klingensmith, K. M.; Alexander, V.

    1983-01-01

    We used a combination of 15N tracer methods and a C2H2 blockage technique to determine the role of sediment nitrification and denitrification in a deep oligotrophic arctic lake. Inorganic nitrogen concentrations ranged between 40 and 600 nmol · cm−3, increasing with depth below the sediment-water interface. Nitrate concentrations were at least 10 times lower, and nitrate was only detectable within the top 0 to 6 cm of sediment. Eh and pH profiles showed an oxidized surface zone underlain by m...

  2. THE EFFECTS OF TEA WASTES ON SOIL ENZYME ACTIVITY AND NITRIFICATION

    OpenAIRE

    ARCAK, Sevinç; A. Cihat KÜTÜK; Koray HAKTANIR; Gökhan ÇAYCI

    1997-01-01

    The research was carried out on tea wastes supplied from factories of General Directorate of Tea Enterprises. The aim of this study is to determine the effects of composted, enriched composted tea wastes along with coarse and fine tea wastes released by tea factories processing raw tea leaves into black tea, on soil enzyme activity and nitrification. Tea wastes were applied to pots of 200 g-soil capacity, at the rate of 0 %, 2.5 % and 5.0 % of the pot capacity in addition, 200 µg/g N, in the...

  3. A sensitive inhibition chemiluminescence method for the determination of 6-mercaptopurine in tablet and biological fluid using the reaction of luminol-Ag(III) complex in alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hanwen, E-mail: hanwen@hbu.edu.cn [College of Chemistry and Environmental Science, Hebei University, Key Laboratory of Analytical Science and Technology of Hebei Province, Baoding 071002 (China); Wang, Ting; Liu, Xuyang; Chen, Peiyun [College of Chemistry and Environmental Science, Hebei University, Key Laboratory of Analytical Science and Technology of Hebei Province, Baoding 071002 (China)

    2013-02-15

    A sensitive inhibition chemiluminescence (CL) method for the determination of 6-mercaptopurine (6-MP) is developed. The mechanism of the CL reaction between Ag(III) complex {l_brace}[Ag(HIO{sub 6}){sub 2}]{sup 5-}{r_brace} and luminol in alkaline solution was proposed, along with the inhibition mechanism of 6-MP on the CL emission. The inhibition degree of CL emission was proportional to the logarithm of 6-MP concentration. The effects of the reaction conditions on CL emission and inhibition were examined. Under the optimized conditions, the detection limit (s/n=3) was 3.7 Multiplication-Sign 10{sup -10} g ml{sup -1}. The recoveries of 6-MP were in the range of 97.7-105% with the RSD of 2.1-3.4% (n=5) for tablet samples, 103-106% with the RSDs of 1.1-2.1% for spiked serum sample, and 97.2-101% with the RSD of 2.0-4.5% for spiked urine sample. The accuracy of this method for the tablet analysis was examined by comparing with the pharmacopoeia method. The proposed method was used for the determination of 6-MP at clinically relevant concentrations in real urine and serum samples with satisfactory results. - Highlights: Black-Right-Pointing-Pointer A sensitive inhibition chemiluminescence (CL) method for the determination of 6-MP is developed. Black-Right-Pointing-Pointer The inhibition mechanism of 6-MP on the CL emission was proposed. Black-Right-Pointing-Pointer The detection limit was 3.7 Multiplication-Sign 10{sup -10} g ml{sup -1}. Black-Right-Pointing-Pointer The accuracy was examined by comparing with the pharmacopoeia method.

  4. A sensitive inhibition chemiluminescence method for the determination of 6-mercaptopurine in tablet and biological fluid using the reaction of luminol–Ag(III) complex in alkaline medium

    International Nuclear Information System (INIS)

    A sensitive inhibition chemiluminescence (CL) method for the determination of 6-mercaptopurine (6-MP) is developed. The mechanism of the CL reaction between Ag(III) complex {[Ag(HIO6)2]5−} and luminol in alkaline solution was proposed, along with the inhibition mechanism of 6-MP on the CL emission. The inhibition degree of CL emission was proportional to the logarithm of 6-MP concentration. The effects of the reaction conditions on CL emission and inhibition were examined. Under the optimized conditions, the detection limit (s/n=3) was 3.7×10−10 g ml−1. The recoveries of 6-MP were in the range of 97.7–105% with the RSD of 2.1–3.4% (n=5) for tablet samples, 103–106% with the RSDs of 1.1–2.1% for spiked serum sample, and 97.2–101% with the RSD of 2.0–4.5% for spiked urine sample. The accuracy of this method for the tablet analysis was examined by comparing with the pharmacopoeia method. The proposed method was used for the determination of 6-MP at clinically relevant concentrations in real urine and serum samples with satisfactory results. - Highlights: ► A sensitive inhibition chemiluminescence (CL) method for the determination of 6-MP is developed. ► The inhibition mechanism of 6-MP on the CL emission was proposed. ► The detection limit was 3.7×10−10 g ml−1. ► The accuracy was examined by comparing with the pharmacopoeia method.

  5. Phosphate limitation in biological rapid sand filters used to remove ammonium from drinking water

    DEFF Research Database (Denmark)

    Lee, Carson Odell; Albrechtsen, Hans-Jørgen; Smets, Barth F.; Boe-Hansen, Rasmus; Lind, Søren; Binning, Philip John

    2013-01-01

    Removing ammonium from drinking water is important for maintaining biological stability in distribution systems. This is especially important in regions that do not use disinfectants in the treatment process or keep a disinfectant residual in the distribution system. Problems with nitrification can...... occur with increased ammonium loads caused by seasonal or operational changes and can lead to extensive periods of elevated ammonium and nitrite concentrations in the effluent. One possible cause of nitrification problems in these filters maybe due to phosphate limitation. This was investigated using a...... limiting substrate. Preliminary results showed an increased nitrification capacity both with and without phosphate addition although the addition of phosphate doubled the ammonium and nitrite removal capacity of the filter compared to non-phosphate dosing conditions. Phosphate addition also increased the...

  6. Evaluation of a Membrane Biological Reactor for Reclaiming Water, Alkalinity, Salts, Phosphorus, and Protein Contained in a High-Strength Aquacultural Wastewater

    Science.gov (United States)

    The capacity of a membrane biological reactor to provide nitrification, denitrification, and enhanced biological phosphorus removal of a high-strength aquaculture backwash flow (control condition), or the same flow amended with 100 mg/L of NO3-N and 3 mg/L of dissolved P (test condition), was assess...

  7. Response of Nematodes in a Hapli-Udic Argosol to Urea Amended with Urease and Nitrification Inhibitors

    Institute of Scientific and Technical Information of China (English)

    HUA Jian-Feng; JIANG Yong; LIANG Wen-Ju

    2006-01-01

    Effects of urea amended with urease and nitrification inhibitors on soil nematode communities were studied in a HapliUdic Argosol (Cambisol, FAO) in Liaoning Province of Northeast China. A completely random design with four treatments,i.e., conventional urea (CU), slow-release urea amended with a liquid urease inhibitor (SRU1), SRU1 + nitrification inhibitor dicyandiamide (SRU2), and SRU1 + nitrification inhibitor 3,5-dimethylpyrazole (SRU3) and four replicates were applied. Thirty-nine genera of nematodes were identified, with Cephalobus and Aphelenchus being dominant; and in all treatments, the dominant trophic group was bacterivores. In addition, during the growth period of spring wheat ( Triticum aestivum L.), soil urease activity was lower in SRUs than in CU. The numbers of total nematodes and bacterivores at wheat heading and ripening stages, and omnivores-predators at ripening stage were higher in SUR3 than in CU, SRU1and SRU2 (P < 0.05).

  8. Fused imidazoles as potential chemical scaffolds for inhibition of heat shock protein 70 and induction of apoptosis. Synthesis and biological evaluation of phenanthro[9,10-d]imidazoles and imidazo[4,5-f][1,10]phenanthrolines.

    Science.gov (United States)

    Patel, Alpa; Sharp, Swee Y; Hall, Katelan; Lewis, William; Stevens, Malcolm F G; Workman, Paul; Moody, Christopher J

    2016-04-28

    The imidazole ring is widespread in biologically active compounds, and hence imidazole-containing scaffolds are useful starting points for drug discovery programmes. We report the synthesis of a series of novel imidazole-containing compounds fused with either phenanthrene or phenanthroline, which show enhanced growth inhibitory potency against human colon, breast and melanoma cancer cell lines, as well as evidence of inhibition of the molecular chaperone heat shock protein 70 (Hsp70) pathway in cells, as shown by depletion of downstream oncogenic client proteins of the Hsp90 chaperone pathway, and induction of apoptosis. PMID:27035072

  9. The Nitrification Inhibitor Methyl 3-(4-Hydroxyphenyl)Propionate Modulates Root Development by Interfering with Auxin Signaling via the NO/ROS Pathway.

    Science.gov (United States)

    Liu, Yangyang; Wang, Ruling; Zhang, Ping; Chen, Qi; Luo, Qiong; Zhu, Yiyong; Xu, Jin

    2016-07-01

    Methyl 3-(4-hydroxyphenyl)propionate (MHPP) is a root exudate that functions as a nitrification inhibitor and as a modulator of the root system architecture (RSA) by inhibiting primary root (PR) elongation and promoting lateral root formation. However, the mechanism underlying MHPP-mediated modulation of the RSA remains unclear. Here, we report that MHPP inhibits PR elongation in Arabidopsis (Arabidopsis thaliana) by elevating the levels of auxin expression and signaling. MHPP induces an increase in auxin levels by up-regulating auxin biosynthesis, altering the expression of auxin carriers, and promoting the degradation of the auxin/indole-3-acetic acid family of transcriptional repressors. We found that MHPP-induced nitric oxide (NO) production promoted reactive oxygen species (ROS) accumulation in root tips. Suppressing the accumulation of NO or ROS alleviated the inhibitory effect of MHPP on PR elongation by weakening auxin responses and perception and by affecting meristematic cell division potential. Genetic analysis supported the phenotype described above. Taken together, our results indicate that MHPP modulates RSA remodeling via the NO/ROS-mediated auxin response pathway in Arabidopsis. Our study also revealed that MHPP significantly induced the accumulation of glucosinolates in roots, suggesting the diverse functions of MHPP in modulating plant growth, development, and stress tolerance in plants. PMID:27217493

  10. Succession of Biofilm Microbial Community during Nitrification in Lab-Scale Reactors Simulating Chloraminated Drinking Water Distribution System Conditions: the Impact of Simultaneously Increasing Monochloramine and Chlorine to Nitrogen Mass Ratios

    Science.gov (United States)

    Chloramination has been shown to promote nitrifying bacteria and 30 to 63% of utility plants using secondary chloramine disinfection experience nitrification episodes. Although nitrifying bacteria are not considered human pathogens, nitrification can affect drinking water qualit...

  11. Inhibition of ER-to-Golgi transport by the coxsackievirus 3A protein : biological significance, underlying mechanism and structure-function relationship of 3A

    NARCIS (Netherlands)

    Wessels, E.

    2006-01-01

    The main objective of the studies described in this thesis was to obtain more insight into the functional and structural aspects of the enterovirus 3A protein. Many viruses modify cellular processes for their own benefit. The enterovirus 3A protein inhibits endoplasmic reticulum (ER)-to-Golgi transp

  12. Complete nitrification-denitrification of swine manure in a full-scale, non-conventional composting system.

    Science.gov (United States)

    Chiumenti, Alessandro

    2015-12-01

    A full-scale composting plant (track type, aerated by screws), treating liquid swine manure (94.8% on mass basis) with straw (genes of Bacterial amoA/gTS and 2.46 ⋅ 10(7) couples NosZ/gTS, indicating nitrification and complete denitrification. These results exhibit that nitrification and complete denitrification can efficiently occur in a composting process effectively transforming N2O into N2 as consequence of the optimized alternation of aerated and anoxic phases in the feedstock. PMID:26257055

  13. Surface Nitrification: A Major Uncertainty in Marine N2O Emissions

    Science.gov (United States)

    Zamora, Lauren M.; Oschlies, Andreas

    2014-01-01

    The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (approaching 100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to approximately 1.6 Tg N/yr (sup -1) or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr (sup -1)or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by less than 15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.

  14. Treatment of nitrogen-rich wastewater using partial nitrification and anammox in the CANON process.

    Science.gov (United States)

    Third, K A; Paxman, J; Schmid, M; Strous, M; Jetten, M S M; Cord-Ruwisch, R

    2005-01-01

    Partial nitrification combined with Anammox in a single reactor (the CANON process) is an energy-efficient N-removal technology that could substantially lower the N-load of a WWTP by separate treatment of nitrogen-rich side streams, preventing the need for extensive expansion and reducing the total energy requirement. This study looks at the enrichment of Anammox from activated sludge and its application in the CANON process on lab-scale. The aim was to identify the critical process control parameters necessary for successful operation of CANON. An Anammox culture capable of removing 0.6 kg N/m3/d was enriched in 14 weeks in a sequencing batch reactor. Nitrifying biomass was inoculated into the Anammox reactor (10% v/v) together with limited oxygen supply (culture. The small flocs formed by the biomass (< 1000 microm) were sensitive to low O2 concentrations (< 0.1 mg/L) which prevented simultaneous nitrification and Anammox. Operation with 20 min aerobiosis and 30 min anaerobiosis was necessary to achieve sustained, completely autotrophic N-removal for an extended period at a rate of 0.08 kg N/m3/d. Essential process control parameters for stable CANON operation were the nitrite concentration, oxygen concentration, pH and the temperature. PMID:16235745

  15. Activated packed bed bioreactor for rapid nitrification in brackish water hatchery systems.

    Science.gov (United States)

    Kumar, V J Rejish; Achuthan, Cini; Manju, N J; Philip, Rosamma; Singh, I S Bright

    2009-03-01

    A packed bed bioreactor (PBBR) was developed for rapid establishment of nitrification in brackish water hatchery systems in the tropics. The reactors were activated by immobilizing ammonia-oxidizing (AMONPCU-1) and nitrite-oxidizing (NIONPCU-1) bacterial consortia on polystyrene and low-density polyethylene beads, respectively. Fluorescence in situ hybridization demonstrated the presence of autotrophic nitrifiers belong to Nitrosococcus mobilis, lineage of beta ammonia oxidizers and nitrite oxidizer Nitrobacter sp. in the consortia. The activated reactors upon integration to the hatchery system resulted in significant ammonia removal (P systems. With spent water the reactors could establish nitrification with high percentage removal of ammonia (78%), nitrite (79%) and BOD (56%) within 7 days of initiation of the process. PBBR is configured in such a way to minimize the energy requirements for continuous operation by limiting the energy inputs to a single stage pumping of water and aeration to the aeration cells. The PBBR shall enable hatchery systems to operate under closed recirculating mode and pave the way for better water management in the aquaculture industry. PMID:19039611

  16. Cinnamaldehyde affects the biological behavior of human colorectal cancer cells and induces apoptosis via inhibition of the PI3K/Akt signaling pathway.

    Science.gov (United States)

    Li, Jiepin; Teng, Yuhao; Liu, Shenlin; Wang, Zifan; Chen, Yan; Zhang, Yingying; Xi, Songyang; Xu, Song; Wang, Ruiping; Zou, Xi

    2016-03-01

    Cinnamaldehyde (CA) is a bioactive compound isolated from the stem bark of Cinnamomum cassia, that has been identified as an antiproliferative substance with pro-apoptotic effects on various cancer cell lines in vitro. In the present study, the effects of CA on human colon cancer cells were investigated at both the molecular and cellular levels. Three types of colorectal cancer cells at various stages of differentiation and invasive ability (SW480, HCT116 and LoVo) were treated with CA at final concentrations of 20, 40 and 80 µg/ml for 24 h. Compared with the control group, the proliferation inhibition rate of the human colorectal cancer cells following treatment with CA increased in a dose- and time-dependent manner. The invasion and adhesion abilities of the cells were significantly inhibited as indicated by Transwell and cell-matrix adhesion assays. Meanwhile, CA also upregulated the expression of E-cadherin and downregulated the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. CA also elevated the apoptotic rate. The levels of pro-apoptotic genes were upregulated while the levels of apoptosis inhibitory genes were decreased which further confirmed the pro-apoptotic effect of CA. In order to explore the mechanism of CA-induced apoptosis, insulin-like growth factor-1 (IGF-1) and PI3K inhibitor (LY294002) were used to regulate the phosphoinositide 3-kinase (PI3K)/AKT pathway. The transcription activity of PI3K/AKT was markedly inhibited by CA, as well as IGF-1 which functions as an anti-apoptotic factor. In conclusion, CA has the potential to be developed as a new antitumor drug. The mechanisms of action involve the regulation of expression of genes involved in apoptosis, invasion and adhesion via inhibition of the PI3K/Akt signaling pathway. PMID:26677144

  17. Inhibition of bacterial and phytoplanktonic metabolic activity in the lower River Rhine by ditallowdimethylammonium chloride.

    Science.gov (United States)

    Tubbing, D M; Admiraal, W

    1991-12-01

    The effects of a quaternary ammonium compound, ditallowdimethylammonium chloride (DTDMAC), on natural populations of bacteria and phytoplankton from the lower River Rhine were examined to estimate their sensitivity to the discharges of cationic surfactants in the river basin. In short-term experiments, significant decreases in the growth rate of bacterioplankton and in the photosynthetic rate of phytoplankton were observed at a nominal concentration of 0.03 to 0.1 mg of DTDMAC liter-1. Nitrification was measured with an ion-selective electrode and by the rate of acid production in ammonium-spiked river water and was found to be only sensitive to the addition of concentrations higher than 1 mg of DTDMAC liter-1. This does not support an earlier suggestion that ammonium-oxidizing bacteria are specifically sensitive to quaternary ammonium compounds. The effect of DTDMAC on thymidine incorporation was shown to depend strongly on the concentration of suspended material, which varied with the sampling date. This effect was also quantified in experimental manipulations with Rhine water. Calculations on the partitioning of DTDMAC between water and suspended matter confirmed the role of suspended solids and showed that an increase of the dissolved DTDMAC concentration in Rhine water by circa 0.01 mg liter-1 leads to a slight inhibition of the growth of heterotrophic bacteria. It is concluded that a total concentration of circa 0.01 mg of DTDMAC liter-1 measured in the River Rhine is likely to have biological consequences. PMID:1785934

  18. Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch.

    Science.gov (United States)

    Lei, Li; Ni, Jinren

    2014-04-15

    A three-dimensional three-phase fluid model, supplemented by laboratory data, was developed to simulate the hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification processes in an oxidation ditch. The model provided detailed phase information on the liquid flow field, gas hold-up distribution and sludge sedimentation. The three-phase model described water-gas, water-sludge and gas-sludge interactions. Activated sludge was taken to be in a pseudo-solid phase, comprising an initially separated solid phase that was transported and later underwent biological reactions with the surrounding liquidmedia. Floc parameters were modified to improve the sludge viscosity, sludge density, oxygen mass transfer rate, and carbon substrate uptake due to adsorption onto the activated sludge. The validation test results were in very satisfactory agreement with laboratory data on the behavior of activated sludge in an oxidation ditch. By coupling species transport and biological process models, reasonable predictions are made of: (1) the biochemical kinetics of dissolved oxygen, chemical oxygen demand (COD) and nitrogen variation, and (2) the physical kinematics of sludge sedimentation. PMID:24525069

  19. Nitrification and denitrification in two-chamber microbial fuel cells for treatment of wastewater containing high concentrations of ammonia nitrogen.

    Science.gov (United States)

    Du, Haixia; Li, Fusheng; Yu, Zaiji; Feng, Chunhua; Li, Wenhan

    2016-05-01

    Simultaneous nitrification and denitrification in the aerated cathode chamber of microbial fuel cells (MFCs) inoculated with nitrifying bacteria were investigated using two-chamber MFCs. Based on the variations of [Formula: see text], [Formula: see text] and [Formula: see text] in the cathode chamber of four MFCs added with different concentrations of [Formula: see text] (50, 65, 130 and 230 mg/L), the occurrence of simultaneous nitrification and denitrification leading to effective removal of nitrogen was confirmed. Electrochemical reaction with electrons transferred from the anode chamber was found to be the major mechanism responsible for the removal of [Formula: see text] in the cathode chamber. The estimated values of the first-order rate constant for nitrification and denitrification varied in the range of 0.3-1.7 day(-1) and 0.2-0.9 day(-1), revealing a decreasing trend with increases in the initial [Formula: see text] concentrations and the detected maximum concentration of the nitrification product of [Formula: see text] in the cathode chamber, respectively. PMID:26507121

  20. Depth investigation of rapid sand filters for drinking water production reveals strong stratification in nitrification biokinetic behavior

    DEFF Research Database (Denmark)

    Tatari, Karolina; Smets, Barth F.; Albrechtsen, Hans-Jørgen

    2016-01-01

    rate, indicating their primarily role in nitrification under the imposed experimental conditions. The maximum AOB cell specific NH4 + removal rate observed at the bottom was at least 3 times lower compared to the top and middle layers. Additionally, a significant up-shift capacity (4.6 and 3.5 times...

  1. Influences of nitrification inhibitor 3,4-dimethyl pyrazole phosphate on nitrogen and soil salt-ion leaching

    Institute of Scientific and Technical Information of China (English)

    YU Qiaogang; YE Xuezhu; CHEN Yingxu; ZHANG Zhijian; TIAN Guangming

    2008-01-01

    An undisturbed heavy clay soil column experiment was conducted to examine the influence of the new nitrification inhibitor,3,4-dimethylpyrazole phosphate (DMPP),on nitrogen and soil salt-ion leaching.Regular urea was selected as the nitrogen source in the soil.The results showed that the cumulative leaching losses of soil nitrate-N under the treatment of urea with DMPP were from 57.5% to 63.3% lower than those of the treatment of urea without DMPP.The use of nitrification inhibitors as nitrate leaching retardants may be a proposal in regulations to prevent groundwater contaminant.However,there were no great difference between urea and urea with DMPP treatments on ammonium-N leaching.Moreover,the soil salt-ion leaching losses of Ca2+,Mg2+,K+,and Na+ were reduced from 26.6% to 28.8%,21.3% to 27.8%,33.3% to 35.5%,and 21.7% to 32.1%,respectively.So,the leaching losses of soil salt-ion were declined for nitrification inhibitor DMPP addition,being beneficial to shallow groundwater protection and growth of crop.These results indicated the possibility of ammonium or ammonium producing compounds using nitrification inhibitor DMPP to control the nitrate and nutrient cation leaching losses,minimizing the risk of nitrate pollution in shallow groundwater.

  2. Spatial and Temporal Patterns of Nitrification Rates in Forested Floodplain Wetland Soils of Upper Mississippi River Pool 8, Journal Article

    Science.gov (United States)

    Overbank flooding is thought to be a critical process controlling nitrogen retention and cycling. In this study we investigated the effects of season and flood frequency on soil nitrification rates at ten sites in forested floodplains of Upper Mississippi River, Pool 8...A rough ...

  3. Legumes or nitrification inhibitors to reduce N2O emissions in subtropical cereal cropping systems? A simulation study

    Science.gov (United States)

    The DAYCENT biogeochemical model was used to investigate how the use of fertilisers coated with nitrification inhibitors and the introduction of legumes in the crop rotation can affect subtropical cereal production and N2O emissions. The model was validated using comprehensive multi-seasonal, high-f...

  4. Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California

    Science.gov (United States)

    Wankel, Scott D.; Kendall, C.; Pennington, J.T.; Chavez, F.P.; Paytan, A.

    2007-01-01

    Coupled measurements of nitrate (NO3-), nitrogen (N), and oxygen (O) isotopic composition (??15NNO3 and ??18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous and variable influence of both phytoplankton NO3- assimilation and nitrification within the euphotic zone. Specifically, increases ??18ONO3 were consistently greater than those in ??15NN03. A coupled isotope steady state box model was used to estimate the amount of NO3- supplied by nitrification in surface waters relative to that supplied from deeper water. The model highlights the importance of the branching reaction during ammonium (NH4+) consumption, in which NH4+ either serves as a substrate for regenerated production or for nitrification. Our observations indicate that a previously unrecognized proportion of nitrate-based productivity, on average 15 to 27%, is supported by nitrification in surface waters and should not be considered new production. This work also highlights the need for a better understanding of isotope effects of NH4+ oxidation, NH4+ assimilation, and NO4+ assimilation in marine environments.

  5. N Mineralization and Nitrification in a Primary Lithocarpus xylocarpus Forest and Degraded Vegetation in the Ailao Mountain, Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    LIGui-Cai; HANXing-Guo; HUANGJian-Hui

    2004-01-01

    Using the closed-top tube incubation method, we examined the soil nitrogen (N) mineralizationand nitrification in the primary Lithocarpus xylocarpus forest, a secondary oak forest and a tea plantationin the Ailao Mountain, Yunnan Province, China. This study was conducted in the dry season fromNovember 20, 1998 to May 15, 1999. Results showed that there were significant differences among thethree vegetation types in both net N mineralization and nitrification rates, and they also demonstratedtemporal variation. The net ammonification rate (RA) was much higher than net nitrification rate (RN), andthe latter was about 0.5%-10% of the former. Our results indicated that incubation period, vegetation typeand the location of plot all interactively affected RA, RN and net mineralization rate (RM). We providedevidence that anthropogenic disturbances could result in changes of ecosystems processes such as Nmineralization and nitrification rates. It is obvious that tea plantation and secondary growth forest havemore physically (mainly temperature and moisture) controlled N transformation processes than thewell-preserved primary L. xylocarpus forest, implying that the conservation of primary forest ecosystemsin the Ailao Mountain region should be emphasized.

  6. 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...

  7. Prediction of Some Biological Film Characteristic

    International Nuclear Information System (INIS)

    A multi components biofilm model has been developed and discussed which accounts for all well established biological processes with biofilm(s): substrate utilization [aerobically, axenically and anaerobically]. Denitrification process. nitrification process. the effect of diffusion and mass transfer limitations. The model has predicted some important characteristics of bio films such as:- space distribution of substrate(s) within bio films. Weight or thickness of biofilm layer (aerobic layer, anoxic layer and anaerobic layer). The results indicates that the relative thickness of biofilm layers (aerobically, anoxically and anaerobic) is highly affected by the availability of the main electron acceptor (O2 and NO3 and the organic load)

  8. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils.

    Science.gov (United States)

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-05-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3(-)-N g(-1) dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in (13)C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of (13)CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the (13)C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The (13)C-NOB was

  9. Relating the Diversity, Abundance, and Activity of Ammonia-Oxidizing Archaeal Communities to Nitrification Rates in the Coastal Ocean

    Science.gov (United States)

    Tolar, B. B.; Smith, J. M.; Chavez, F.; Francis, C.

    2015-12-01

    Ammonia oxidation, the rate-limiting first step of nitrification, is an important link between reduced (ammonia) and oxidized (nitrate) nitrogen, and controls the relative distribution of these forms of inorganic nitrogen. This process is catalyzed via the ammonia monooxygenase enzyme of both ammonia-oxidizing Bacteria (AOB) and Archaea (AOA); the α subunit of this enzyme is encoded by the amoA gene and has been used as the molecular marker to detect this process. In the ocean, AOA are typically 10-1000 times more and are likely more active than AOB, and thus are key players in the marine nitrogen cycle. Monterey Bay is a dynamic site to study nitrification, as seasonal upwelling brings deep water and nutrients into surface waters, which can promote phytoplankton blooms and impact biogeochemical processes such as the nitrogen cycle. We have sampled two sites within Monterey Bay bimonthly for two years as part of the ongoing Monterey Bay Time Series (MBTS) to quantify AOA genes, transcripts, and nitrification rates. Two ecotypes of AOA are routinely found in Monterey Bay - the 'shallow' water column A (WCA) and 'deep' water column B (WCB) clades, which are thought to have distinct physiological properties and can be distinguished based on the amoA gene sequence. Previous work has shown a strong relationship between nitrification rates in Monterey Bay with the abundance of WCA amoA genes and transcripts. Additionally, we found a correlation between the relative abundance of Marine Group I (MGI) Thaumarchaeota 16S rRNA reads (as % of total) and the absolute abundance of AOA amoA genes (determined via qPCR) in Monterey Bay and the California Current System. AOA 16S rRNA gene abundances in turn correlated significantly with changes in nitrification rate with depth, while the relative abundance of genes and transcripts binned to a single AOA (Nitrosopumilus maritimus) was not significantly correlated to nitrification rate. Further analysis of the sequenced AOA

  10. A robust and cost-effective integrated process for nitrogen and bio-refractory organics removal from landfill leachate via short-cut nitrification, anaerobic ammonium oxidation in tandem with electrochemical oxidation.

    Science.gov (United States)

    Wu, Li-Na; Liang, Da-Wei; Xu, Ying-Ying; Liu, Ting; Peng, Yong-Zhen; Zhang, Jie

    2016-07-01

    A cost-effective process, consisting of a denitrifying upflow anaerobic sludge blanket (UASB), an oxygen-limited anoxic/aerobic (A/O) process for short-cut nitrification, and an anaerobic reactor (ANR) for anaerobic ammonia oxidation (anammox), followed by an electrochemical oxidation process with a Ti-based SnO2-Sb2O5 anode, was developed to remove organics and nitrogen in a sewage diluted leachate. The final chemical oxygen demand (COD), ammonia nitrogen (NH4(+)-N) and total nitrogen (TN) of 70, 11.3 and 39 (all in mg/L), respectively, were obtained. TN removal in UASB, A/O and ANR were 24.6%, 49.6% and 16.1%, respectively. According to the water quality and molecular biology analysis, a high degree of anammox besides short-cut nitrification and denitrification occurred in A/O. Counting for 16.1% of TN removal in ANR, at least 43.2-49% of TN was removed via anammox. The anammox bacteria in A/O and ANR, were in respective titers of (2.5-5.9)×10(9) and 2.01×10(10)copy numbers/(gSS). PMID:27115616

  11. Short- and long-term effects of temperature on partial nitrification in a sequencing batch reactor treating domestic wastewater

    International Nuclear Information System (INIS)

    Partial nitrification to nitrite has been frequently obtained at high temperatures, but has proved difficult to achieve at low temperatures when treating low strength domestic wastewater. In this study, the long-term effects of temperature on partial nitrification were investigated by operating a sequencing bath reactor with the use of aeration duration control. The specific ammonia oxidation rate decreased by 1.5 times with the temperature decreasing from 25 to 15 deg. C. However, low temperature did not deteriorate the stable partial nitrification performance. Nitrite accumulation ratio was always above 90%, even slightly higher (above 95%) at low temperatures. The nitrifying sludge accumulated with ammonia-oxidizing bacteria (AOB), but washout of nitrite-oxidizing bacteria (NOB) was used to determine the short-term effects of temperature on ammonia oxidation process. The ammonia oxidation rate depended more sensitively on lower temperatures; correspondingly the temperature coefficient θ was 1.172 from 5 to 20 deg. C, while θ was 1.062 from 20 to 35 deg. C. Moreover, the larger activation energy (111.5 kJ mol-1) was found at lower temperatures of 5-20 deg. C, whereas the smaller value (42.0 kJ mol-1) was observed at higher temperatures of 20-35 deg. C. These findings might be contributed to extend the applicability of the partial nitrification process in wastewater treatment plants operated under cold weather conditions. It is suggested that the selective enrichment of AOB as well as the washout of NOB be obtained by process control before making the biomass slowly adapt to low temperatures for achieving partial nitrification to nitrite at low temperatures.

  12. Tracing nitrification and denitrification processes in a periodically flooded shallow sandy aquifer

    International Nuclear Information System (INIS)

    The study defines the transfer mechanisms of nutrients and heavy metals from soil to groundwater operating in periodically water saturated soils. The study site is located in Lomellina (Po plain, Northern Italy), which is intensively cultivated with rice. Soils are dominantly constituted by sands, with acidic pH and low organic carbon content. The region generally displays low nitrate contamination in shallow groundwater, despite the intensive land use, while Fe and Mn often exceed drinking water limits. Monitoring performed through a yearly cycle closely followed the water table fluctuations in response to periodical flooding and drying of cultivated fields. pH, conductivity and Eh were measured in the field. Water samples were analysed for major ions, trace elements, nutrients and stable isotopes of DIN. Results evidence the seasonal migration of nutrients, the redox and associated metal cycling, and allow defining nitrification and denitrification processes. (author)

  13. Tracing nitrification and denitrification processes in a periodically flooded shallow sandy aquifer

    International Nuclear Information System (INIS)

    The study defines the transfer mechanisms of nutrients and heavy metals from soil to groundwater operating in periodically water saturated soils. The study site is located in Lomellina (To plain, Northern Italy), which is intensively cultivated with rice. Soils are dominantly constituted by sands, with acidic pH and low organic carbon content. The region generally displays low nitrate contamination in shallow groundwater, despite the intensive land use, while Fe and Mn often exceed drinking water limits. Monitoring performed through a yearly cycle closely followed the water table fluctuations in response to periodical flooding and drying of cultivated fields. pH, conductivity and Eh were measured in the field. Water samples were analysed for major ions, trace elements, nutrients and stable isotopes of dissolved inorganic nitrate (DIN). Results evidence the seasonal migration of nutrients, the redox and associated metal cycling, and allow defining nitrification and denitrification processes. (author)

  14. Simultaneous nitrification and denitrification in activated sludge system under low oxygen concentration

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; ZHOU Qi

    2007-01-01

    Simultaneous nitrification and denitrification(SND),which is more economical compared with the traditional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process,a mixed flow activated sludge system under low oxygen concentration is investigated,and some key control parameters are examined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentration is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7% with solids retention time(SRT)0f 45 d,C/N value of 10,and F/M ratio of 0]1g COD/(g MLSS-d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.

  15. Model Development and Simulation of Nitrification in SHARON Reactor in Moderate Temperature by Simulink

    Directory of Open Access Journals (Sweden)

    Dr. Adnan Abbas Al-Samawi

    2015-11-01

    Full Text Available In order to reduce the nitrogen compounds in WWTP effluent according to legislations, nitrogen of reject water is removed in separate unit by applying innovative cost effective process named SHARON (Single reactor High activity Ammonium Removal Over Nitrite process which is feasible to apply in moderate weather and more cost effective process due to elimination the heat exchanger required to keep the reject water of high temperature. In addition to the save in oxygen requirement to oxide ammonium by preventing nitrite oxidation and the saving in external COD addition for denitrification. Also, there is no need for large reactor volume because HRT equal to SRT. Significant mathematical model of nitrification process in SHARON reactor was developed based on substances and organisms mass balance as well as organisms kinetics. A relatively favorable consistency was obtained between the experimental and the predicted results of model. A high correlation of (R2=0.946 between model predictions and experimental data sets.

  16. Nitrification and denitrifying phosphorus removal in an upright continuous flow reactor.

    Science.gov (United States)

    Reza, Maryam; Alvarez Cuenca, Manuel

    2016-01-01

    Simultaneous nitrification and denitrifying phosphorus removal was achieved in a single-sludge continuous flow bioreactor. The upright bioreactor was aligned with a biomass fermenter (BF) and operated continuously for over 350 days. This study revealed that unknown bacteria of the Saprospiraceae class may have been responsible for the successful nutrient removal in this bioreactor. The successive anoxic-aerobic stages of the bioreactor with upright alignment along with a 60 L BF created a unique ecosystem for the growth of nitrifier, denitrifiers, phosphorus accumulating organisms and denitrifying phosphorus accumulating organisms. Furthermore, total nitrogen to chemical oxygen demand (COD) ratio and total phosphorus to COD ratio of 0.6 and 0.034, respectively, confirmed the comparative advantages of this advanced nutrient removal process relative to both sequencing batch reactors and activated sludge processes. The process yielded 95% nitrogen removal and over 90% phosphorus removal efficiencies. PMID:27148710

  17. Measuring nitrification inhibition by metals in wastewater treatment systems: Current state of science and fundamental research needs

    Science.gov (United States)

    Wastewater treatment is an important step within the water continuum as it reduces the risks associated with microorganisms as well as organic and inorganic compounds. From a chemical standpoint, treatment effectiveness is linked to carbon and nitrogen removal, although phosphate...

  18. Air-lift internal loop biofilm reactor for realized simultaneous nitrification and denitrification.

    Science.gov (United States)

    Zhang, Cuiyi; Wang, Lu; Yan, Ning; Zhang, Yongming; Liu, Rui

    2013-05-01

    Simultaneous nitrification and denitrification (SND) was realized by means of a novel air-lift internal loop biofilm reactor, in which aeration was set in middle of the reactor. During operation, the aeration was adjusted to get appropriate dissolve oxygen (DO) in bulk solution and let aerobic and anoxic zone coexist in one reactor. When aeration was at 0.6 and 0.2 L/min, corresponding to DO of 5.8 and 2.5 mg/L in bulk solution, ammonia nitrogen removal percentage reached about 80 and 90 %, but total nitrogen removal percentage was lower than 25 %. While the aeration was reduced to 0.1 L/min, aerobic and anoxic zones existed simultaneously in one reactor to get 75 % of ammonia nitrogen and 50 % of total nitrogen removal percentage. Biofilms were, respectively, taken from aerobic and anoxic zone to verify their function of nitrification and denitrification in two flasks, in which ammonia nitrogen was transferred into nitrate completely by aerobic biofilm, and nitrate was removed more than 80 % by anoxic biofilm. Microelectrode was used to measure the DO distribution inside biofilms in anoxic zone corresponding to different aerations. When aeration was at 0.6 and 0.2 L/min, DO inside biofilm was more than 1.5 mg/L, but the DO inside biofilm decreased to anoxic status with depth of biofilm increasing corresponding to aeration of 0.1 L/min. The experimental results indicated that SND could be realized because of simultaneous existence of aerobic and anoxic biofilms in one reactor. PMID:23001679

  19. Occurrence and fate of nitrification and urease inhibitors in the aquatic environment.

    Science.gov (United States)

    Scheurer, Marco; Brauch, Heinz-Jürgen; Schmidt, Carsten K; Sacher, Frank

    2016-08-10

    Nitrification and urease inhibitors (NUIs) decelerate the bacterial oxidation of nitrogen species by suppressing the activity of soil microorganisms. Thus, nitrogen losses can be limited and the efficiency of nitrogen fertilizers can be increased. After application NUI transfers to surface water may occur through leaching or surface run-off. In order to assess the occurrence of nitrification and urease inhibitors in the aquatic environment a multi-analyte high-performance liquid chromatography-mass spectrometry method was developed. 1H-1,2,4-Triazole and dicyandiamide (DCD) were detected for the first time in German surface waters. Only at a few sites 1H-1,2,4-triazole has been episodically detected with concentrations up to the μg L(-1)-range. DCD was ubiquitously present in German surface waters. An industrial site was identified as the point source of DCD being responsible for exceptionally high DCD concentrations of up to 7.2 mg L(-1) in close proximity to the point of discharge. Both compounds were also detected in at least one wastewater treatment plant effluent, but their concentrations in surface waters did not correlate with those of typical markers for domestic wastewater. Other NUIs were not detected in any of the samples. Laboratory-scale batch tests proved that 1H-1,2,4-triazole and DCD are not readily biodegradable, are not prone to hydrolysis and do not tend to adsorb onto soil particles. Ozonation and activated carbon filtration proved to be ineffective for their removal. PMID:27058057

  20. Organic matter and concentrated nitrogen removal by shortcut nitrification and denitrification from mature municipal landfill leachate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-jun; PENG Yong-zhen; WANG Shu-ying; ZHENG Shu-wen; GUO Jin

    2007-01-01

    An UASB+Anoxic/Oxic (A/O) system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio and high ammonia concentration. To make the best use of the biodegradable COD in the leachate, the denitrification of NOx-N in the recirculation effluent from the clarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrification in the UASB. The NH4+-N loading rate (ALR) of A/O reactor and operational temperature was 0.28-0.60 kg NH4+-N/(m3·d) and 17-29℃ during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%-99% was stabilized during the whole experiment. The NH4+-N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4+-N/(m3·d), the NH4+-N removal efficiency was more than 98%. With the influent NH4+-N of 1200-1800 mg/L, the effluent NH4+-N was less than 15 mg/L. The shortcut nitrification and denitrification can save 40% carbon source, with a highly efficient denitrification taking place in the UASB. When the ratio of the feed COD to feed NH4+-N was only 2-3, the total inorganic nitrogen (TIN) removal efficiency attained 67%-80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria (AOB) accounted for 4% of the total eubacterial population, whereas nitrite oxidation bacteria (NOB) accounted only for 0.2% of the total eubacterial population.

  1. Influence of natural zeolite and nitrification inhibitor on organics degradation and nitrogen transformation during sludge composting.

    Science.gov (United States)

    Zhang, Junya; Sui, Qianwen; Li, Kun; Chen, Meixue; Tong, Juan; Qi, Lu; Wei, Yuansong

    2016-01-01

    Sludge composting is one of the most widely used treatments for sewage sludge resource utilization. Natural zeolite and nitrification inhibitor (NI) are widely used during composting and land application for nitrogen conservation, respectively. Three composting reactors (A--the control, B--natural zeolite addition, and C--3,4-dimethylpyrazole phosphate (DMPP) addition) were established to investigate the influence of NI and natural zeolite addition on organics degradation and nitrogen transformation during sludge composting conducted at the lab scale. The results showed that, in comparison with the control, natural zeolite addition accelerated organics degradation and the maturity of sludge compost was higher, while the DMPP addition slowed down the degradation of organic matters. Meanwhile, the nitrogen transformation functional genes including those responses for nitrification (amoA and nxrA) and denitrification (narG, nirS, nirK, and nosZ) were quantified through quantitative PCR (qPCR) to investigate the effects of natural zeolites and DMPP addition on nitrogen transformation. Although no significant difference in the abundance of nitrogen transformation functional genes was observed between treatments, addition of both natural zeolite and DMPP increases the final total nitrogen content by 48.6% and 23.1%, respectively. The ability of natural zeolite for nitrogen conservation was due to the absorption of NH3 by compost, and nitrogen conservation by DMPP was achieved by the source reduction of denitrification. Besides, it was assumed that the addition of natural zeolite and DMPP may affect the activity of these genes instead of the abundance. PMID:26358216

  2. HGF–MET Cascade, a Key Target for Inhibiting Cancer Metastasis: The Impact of NK4 Discovery on Cancer Biology and Therapeutics

    Directory of Open Access Journals (Sweden)

    Shinya Mizuno

    2013-01-01

    Full Text Available Hepatocyte growth factor (HGF was discovered in 1984 as a mitogen of rat hepatocytes in a primary culture system. In the mid-1980s, MET was identified as an oncogenic mutant protein that induces malignant phenotypes in a human cell line. In the early 1990s, wild-type MET was shown to be a functional receptor of HGF. Indeed, HGF exerts multiple functions, such as proliferation, morphogenesis and anti-apoptosis, in various cells via MET tyrosine kinase phosphorylation. During the past 20 years, we have accumulated evidence that HGF is an essential conductor for embryogenesis and tissue regeneration in various types of organs. Furthermore, we found in the mid-1990s that stroma-derived HGF is a major contributor to cancer invasion at least in vitro. Based on this background, we prepared NK4 as an antagonist of HGF: NK4 inhibits HGF-mediated MET tyrosine phosphorylation by competing with HGF for binding to MET. In vivo, NK4 treatments produced the anti-tumor outcomes in mice bearing distinct types of malignant cancers, associated with the loss in MET activation. There are now numerous reports showing that HGF-antagonists and MET-inhibitors are logical for inhibiting tumor growth and metastasis. Additionally, NK4 exerts anti-angiogenic effects, partly through perlecan-dependent cascades. This paper focuses on the chronology and significance of HGF-antagonisms in anti-tumor researches, with an interest in NK4 discovery. Tumor HGF–MET axis is now critical for drug resistance and cancer stem cell maintenance. Thus, oncologists cannot ignore this cascade for the future success of anti-metastatic therapy.

  3. Start-up of single-stage partial nitrification-anammox process treating low-strength swage and its restoration from nitrate accumulation.

    Science.gov (United States)

    Miao, Yuanyuan; Zhang, Liang; Yang, Yandong; Peng, Yongzhen; Li, Baikun; Wang, Shuying; Zhang, Qian

    2016-10-01

    A single-stage partial nitrification-anammox (PN/A) reactor treating low-strength swage was operated for 288days to investigate the recovery of nitrogen removal from nitrate accumulation. The reactor was quickly started up by inoculating anammox sludge. However, nitrite oxidizing bacteria (NOB) abundance gradually increased on day 25, leading to high effluent nitrate concentration. Two strategies were executed to control the effluent nitrate. In strategy I, dissolved oxygen (DO) concentration was kept low (0.17±0.08mg/L), but nitrate production increased from 4.71 to 38.18mg-N/L. In strategy II, intermittent aeration operation mode (aeration 7min/anoxic 21min) was adopted, which significantly lowered the nitrate concentration to 1.3mg-N/L, indicating the NOB was inhibited. The high nitrogen removal rate of 73mg-N/(L·d) was achieved. The evolution of bacterial activity and abundance verified the changes of the nitrogen removal performance and proved the intermittent aeration strategy could successfully solve the problem of nitrate build-up in the PN/A process. PMID:27423544

  4. 基于ETS活性的有机物降解与硝化过程中微生物动力学%Sludge microbial kinetics in organic matter biodegradation and nitrification based on ETS activity

    Institute of Scientific and Technical Information of China (English)

    王建辉; 尹军; 陆海; 王源铭; 林英姿

    2014-01-01

    The variation of electron transport system(ETS)activity during organic matter biodegradation and nitrification was studied to evaluate the feasibility of assessment of biological activity of activated sludge by ETS activity. The Michaelis - Menten equation was used to analyze the kinetics of organic matter oxidation and nitrification. The experimental result showed that ETS activity could reflect the reaction course of organic matter biodegradation and nitrification, and the changes in loading and alkalinity. Therefore, ETS activity could be used as a parameter for assessing the biological activity of activated sludge. The Michaelis constants were KTs=368.9 mg·L-1, UTm=90.9 mg TF·(g TSS·h)-1, KiIs=88.42 mg·L-1, UIm=277.8 mg INTF·(g TSS·h)-1 during organic matter biodegradation. The Michaelis constants were KTs=16.89 mg·L-1,UTm=34.6 mg TF·(g TSS·h)-1, KTs=6.0 mg·L-1, UIm=196.08 mg INTF·(g TSS·h)-1 during nitrification. The results further showed that heterotrophic bacteria growth rate in biodegradation of organic matter was higher than autotrophic denitrifying bacteria growth rate in nitrification of organic matter.%通过考察有机物生物降解和氨氮生物硝化过程中活性污泥电子传递体系(ETS)活性的变化规律,研究了ETS活性表征污泥生物活性的可行性,结合米门公式分析了有机物生物降解和硝化反应过程生物活性动力学。试验结果表明,活性污泥的ETS活性可以有效地揭示出有机物生物降解和氨氮生物硝化反应的进程,同时对系统受到的有机物和氨氮冲击负荷及硝化过程中碱度的变化有着灵敏的反映,这说明用ETS活性表征污泥的生物活性是可行的;有机物生物降解过程生物活性米氏常数KTs=368.9 mg·L-1,UTm=90.9 mg TF·(g TSS·h)-1,KIs=88.42 mg·L-1, UIm=277.8 mg INTF·(g TSS·h)-1;氨氮硝化过程生物活性米氏常数KTs=16.89 mg·L-1,UTm=34.6 mg TF·(g TSS·h)-1, KIs=6.0 mg·L-1

  5. Nitrification and inorganic nitrogen distribution in a large perturbed river/estuarine system: the Pearl River Estuary, China

    Directory of Open Access Journals (Sweden)

    Minhan Dai

    2008-04-01

    Full Text Available We investigated the spatial distribution and seasonal variation of dissolved inorganic nitrogen in a large perturbed estuary, the Pearl River Estuary, based on three cruises conducted in winter (January 2005, summer (August 2005 and spring (March 2006. On-site incubation was also carried out for determining ammonium and nitrite oxidation rates (nitrification rates. We observed a year-round pattern of dramatic decrease in NH4+, increase in NO3 but insignificant change in NO2 in the upper estuary at salinity ~0–5. However, species and concentrations of inorganic nitrogen at estuary significantly changed with season. In winter with low runoff the most upper reach of the Pearl River Estuary showed relatively low rates of ammonia oxidation (0–5.4 μmol N L−1 d−1 and nitrite oxidation (0–5.2 μmol N L−1 d−1, accompanied by extremely high concentrations of ammonia (up to >800 μmol L−1 and nitrate (up to >300 μmol L−1. In summer, the upper estuary showed higher nitrification rates (ammonia oxidation rate ~1.5–33.1 μmol N L−1 d−1, nitrite oxidation rate ~0.6–32.0 μmol N L−1 d−1 with lower concentrations of ammonia (<350 μmol L−1 and nitrate (<120 μmol L−1. The Most Probable Number test showed relatively lower nitrifier abundance in summer at most sampling stations, indicating a greater specific nitrification rate per cell in the warm season. Temperatures appeared to control nitrification rates to a large degree in different seasons. In addition to aerobic respiration, nitrification contributed significantly to the consumption of dissolved oxygen (DO and production of CO2 at the upper estuary. Nitrification-induced DO consumption accounted for approximately up to one third of the total water column

  6. Forcing contact inhibition of locomotion

    OpenAIRE

    Roycroft, A.; Mayor, R.

    2015-01-01

    Contact inhibition of locomotion drives a variety of biological phenomenon, from cell dispersion to collective cell migration and cancer invasion. New imaging techniques have allowed contact inhibition of locomotion to be visualised in vivo for the first time, helping to elucidate some of the molecules and forces involved in this phenomenon.

  7. Interactions between microbial processes, nutrient cycle and grass cover functioning: study of soil nitrification under the Gramineae Hyparrhenia diplandra in a wet tropical savanna of Ivory Coast.

    OpenAIRE

    Lata, Jean-Christophe

    1999-01-01

    Soil nitrification is an important process that partly controls nitrogen availability for plants and nitrogen conservation at ecosystem level. This process is particularly critical in nutrient-poor systems like the wet savanna of Lamto (West Africa) where nitrogen is considered as the major factor limiting primary production. Savanna facies dominated by the grass Hyparrhenia diplandra are known to exhibit low levels of nitrification and thus avoid nitrate losses. We used high/low nitrificatio...

  8. Study of hydraulic and toxic shocks in two anaerobic-aerobic Pilot Moving Bed Biofilm Reactors used for nitrification and denitrification

    International Nuclear Information System (INIS)

    Pilot Moving Bed Biofilm Reactors fed on synthetic wastewater, were used in order to study nitrification and denitrification of high concentration wastewater. To investigate the stability of the nitrification and denitrification process in moving bed biofilm systems, a hydraulic shock and a toxic shock were applied to the system. These two systems showed high stability and process efficiency did not change significantly, in spite of intensive variation during the applied shocks

  9. Potential for nitrogen fixation and nitrification in the granite-hosted subsurface at Henderson Mine, CO

    Directory of Open Access Journals (Sweden)

    Elizabeth eSwanner

    2011-12-01

    Full Text Available The existence of life in the deep terrestrial subsurface is established, yet few studies have investigated the origin of nitrogen that supports deep life. Previously, 16S rRNA gene surveys catalogued a diverse microbial community in subsurface fluids draining from boreholes 3000 feet deep at Henderson Mine, CO (Sahl et al., 2008. The prior characterization of the fluid chemistry and microbial community forms the basis for the further investigation here of the source of NH4+. The reported fluids chemistry included N2, NH4+ (5-112 μM, NO2- (27-48 μM and NO3- (17-72 μM. In this study, the correlation between low NH4+ concentrations in dominantly meteoric fluids and higher NH4+ in rock-reacted fluids is used to hypothesize that NH4+ is sourced from NH4+-bearing biotite. However, biotite samples from the host rocks and ore-body minerals were analyzed by Fourier Transform Infrared (FTIR microscopy and none contained NH4+. However, the nitrogenase-encoding gene nifH was successfully amplified from DNA of the fluid sample with high NH4+, suggesting that subsurface microbes have the capability to fix N2. If so, unregulated nitrogen fixation may account for the relatively high NH4+ concentrations in the fluids. Additionally, the amoA and nxrB genes for archeaeal ammonium monooxygenase and nitrite oxidoreductase, respectively, were amplified from the high-NH4+ fluid DNA, while bacterial amoA genes were not. Putative nitrifying organisms are closely related to ammonium-oxidizing Crenarchaeota and nitrite-oxidizing Nitrospira detected in other subsurface sites based upon 16S rRNA sequence analysis. Thermodynamic calculations underscore the importance of NH4+ as an energy source in a subsurface nitrification pathway. These results suggest that the subsurface microbial community at Henderson is adapted to the low nutrient and energy environment by their capability of fixing nitrogen, and that fixed nitrogen may support subsurface biomass via nitrification.

  10. Effects of Nitrification Inhibitors and Sulphur Coated Urea(SCU)on Different Nitrogen Sources and Wheat Yield%几种硝化抑制剂和包硫尿素(SCU)对土壤N素形态和小麦产量的影响

    Institute of Scientific and Technical Information of China (English)

    李永强; 王雅楣; 杨越超; 贾继文; 解璐晗; 姚瑶; 焦树英

    2016-01-01

    Nitrogen is essential for plant growth and health, and it is also a limiting factor for the growth in most agricultural systems. Intensive N fertilizer application has become the traditional habit for agricultural producers in China because of its importance to plant productivity and agricultural land profitability. But some problems have appeared with the increase of the amount of nitrogen fertilizer applied, urea used in crops is easy to lose from volatilization or leaching. Therefore, current crop management practices lead to a highly nitrifying soil environments. Nitrogen emission is the main source of soil acidity and environmental pollution. Several methods for the use of slow controlled release urea have been reported to be used to control the pollution and to enhance nitrogen use efficiency. There is a growing interest in the formulations ofcoated chemical fertilizers with both urease inhibitor and nitrification inhibitor. Urease inhibitor and nitrification inhibitor may improve urea N-use efficiency and minimize N losses by gaseous emissions of ammonia(NH3)to the atmosphere and nitrate(NO-3)leaching into the surface and ground water. Dicyandiamide(DCD)is a nitrification inhibitor that has been studied for many years, it can effectively inhibit nitrification and N2O emission in many agricultural ecosystems. However, limited information is available on the use of the combination of nitrification inhibitor and urease inhibitor applied with urea fertilizer, especially for thiourea(THU)and thiourea formaldehyde resin(TFR)applications. Therefore the purpose of this study is to investigate the effect of urea with different inhibitors to improve the efficiency of nitrogen utilization. A field pot experiment was conducted to explore how to increase the concentration of DCD/THU/TFR/sulfur-coated urea(SCU)to affect the transformation of soil nitrogen and wheat yield. The experiment was designed for twelve treatments which included no nitrogen(CK), only urea, SCU and

  11. Empirical evidence reveals seasonally dependent reduction in nitrification in coastal sediments subjected to near future ocean acidification

    OpenAIRE

    Braeckman, U; Van Colen, C.; Guilini, K.; Van Gansbeke, D.; Soetaert, K.; Vincx, M.; Vanaverbeke, J

    2014-01-01

    Research so far has provided little evidence that benthic biogeochemical cycling is affected by ocean acidification under realistic climate change scenarios. We measured nutrient exchange and sediment community oxygen consumption (SCOC) rates to estimate nitrification in natural coastal permeable and fine sandy sediments under pre-phytoplankton bloom and bloom conditions. Ocean acidification, as mimicked in the laboratory by a realistic pH decrease of 0.3, significantly reduced SCOC on averag...

  12. Optimization of Nitrogen Removal from Synthetic Wastewater by Eliminating Nitrification Step of a Fixed-Film Bed Reactor

    Directory of Open Access Journals (Sweden)

    M Hajsardar

    2016-06-01

    Full Text Available Background and Objectives: In order to optimize wastewater nitrogen removal and to reduce the problems of entering nutrients in final receptors, for example, a lake, partial nitrification, as a novel nitrogen removal method, was studied. Materials and Methods: The efficiency of simultaneous nitrification and denitrification (SND in partial nitrification through nitrification/denitrification in fixed-film reactor was surveyed. In this process, ammonium was converted to nitrite by ammonium oxidizing bacteria (AOB but the activity of nitrite oxidizing bacteria (NOB was limited at low dissolved oxygen (DO level. The inflection points of oxidation-reduction potential (ORP profile were used as the indicators of process optimization. Results: This research showed that in period 2 at fixed DO level of 0.5 mg/L, nitrite accumulation rate (NAR was higher than period 1 in which DO was declined from 1 to 0.5 mg/L. In contrast to period 1, SND efficiency was reduced in period 2. In period 3, by increment of the carbon to nitrogen ratio (C/N to 12.5, NAR increased to 71.4 % and SND efficiency increased to 96.7%. In the long term analysis of proposed method, SND efficiency was, at least, 90%.    Conclusion: Proper C/N ratio and minimum DO level resulted in higher nitrogen removal efficiencies than the operation in which DO was decreased during aerobic phase. By using a fixed-film reactor and without considering an anoxic step, at DO level of 0.5 mg/L, maximum SND efficiency and maximum NAR would be achieved. 

  13. Direct contribution of clams (Ruditapes philippinarum) to benthic fluxes, nitrification, denitrification and nitrous oxide emission in a farmed sediment

    Science.gov (United States)

    Welsh, David T.; Nizzoli, Daniele; Fano, Elisa A.; Viaroli, Pierluigi

    2015-03-01

    The influence of the manila clam (Ruditapes philippinarum) on N-cycle processes, and oxygen and nutrient fluxes in a farmed sediment was investigated using a multiple core incubation approach and parallel incubations of individual clams. Clam population/biomass density varied ∼8-fold between cores and all sediment-water column solute (O2. N2, N2O, NH4+, NOX and DIN) fluxes and benthic process (N-regeneration, nitrification and denitrification) rates were strongly and significantly correlated with clam density/biomass. Isolated clams exhibited high rates of respiration, N-excretion, nitrification and denitrification of 2050 ± 70, 395 ± 49, 201 ± 42 and 235 ± 40 nmol individual-1 h-1, respectively. The direct contribution of the clams and their associated microbiota to benthic processes was estimated by multiplying the per individual rates by the number of clams in each incubated core. The clams on average directly accounted for 64-133% of total rates of sediment oxygen demand, N-regeneration, nitrification and denitrification, indicating that they regulated processes primarily through their own metabolic activity and that of bacteria that colonise them. Clams and the farmed sediments were significant sources of the greenhouse gas N2O, but this was primarily due to their high nitrification and denitrification rates, rather than high specific N2O yields, as N2O emissions represented environmental cost of increased N-regeneration and N2O emission rates. The measured N2O emissions indicate that bivalve aquaculture may be a significant source of N2O. It is therefore recommended that N2O emissions should be included in the impact assessments of current and future bivalve-farming projects.

  14. A New Developed Airlift Reactor Integrated Settling Process and Its Application for Simultaneous Nitrification and Denitrification Nitrogen Removal

    OpenAIRE

    Tao Zhang; Chaohai Wei

    2013-01-01

    This study presented the performance of simultaneous nitrification and denitrification (SND) process using a new developed hybrid airlift reactor which integrated the activated sludge reaction process in the airlift reactor and the sludge settling separation process in the clarifier. The proposed reactor was started up successfully after 76 days within which the COD and total nitrogen removal rate can reach over 90% and 76.3%, respectively. The effects of different COD/N and DO concentrations...

  15. 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

  16. Effects of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils

    Institute of Scientific and Technical Information of China (English)

    WU Shao-fu; WU Liang-huan; SHI Qi-wei; WANG Zhong-qiang; CHEN Xian-you; LI Yong-shan

    2007-01-01

    In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3--N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3--N leaching significantly, whereas ammonium (NH4+-N) leaching increased slightly. In case of total N (NO3--N+NH4+-N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea+DMPP), 108.10 mg (ASN), 60.70 mg (ASN+DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea+DMPP), 37.86 mg (ASN), 31. 09 mg (ASN+DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4+-N and low levels of NO3--N in soil, and nitrification was slower. DMPP supplementation also resulted in potassium leached less, but the difference was not significant except the treatment ASN and ASN+DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

  17. Greenhouse gas emission and microbial community dynamics during simultaneous nitrification and denitrification process.

    Science.gov (United States)

    Kong, Qiang; Wang, Zhi-Bin; Niu, Peng-Fei; Miao, Ming-Sheng

    2016-06-01

    This study evaluates greenhouse gas emission and the microbial community dynamics during simultaneous nitrification and denitrification (SND) process. Based on CO2 equivalents, the SND reactor released 4.28g of greenhouse gases each cycle. 2.91% of the incoming nitrogen load was emitted as N2O. The CO2 and N2O emissions mainly occurred in the aerobic stage and CH4 emissions were consistently near zero. Extracellular polymeric substance (EPS) contents in activated sludge increased during start-up the SND process. High-throughput sequencing showed increases in bacterial species richness, leading to changes in EPS content and composition observed using 3D-EEM fluorescence spectra. For denitrifying bacteria, the relative abundance of Pseudomonas significantly increased during the SND process, while Paracoccus decreased significantly. For phosphorus-accumulating bacteria, the relative abundance of Rhodocyclaceae also significantly increased. The relative abundance of other functional microbes, such as Nitrosomonadaceae (ammonia oxidizer), Nitrospirales (nitrite oxidizer) and Planctomyces (anammox) decreased significantly during the SND process. PMID:26935325

  18. Nitrogen removal by Providencia rettgeri strain YL with heterotrophic nitrification and aerobic denitrification.

    Science.gov (United States)

    Ye, Jun; Zhao, Bin; An, Qiang; Huang, Yuan-Sheng

    2016-09-01

    Providencia rettgeri strain YL shows the capability of nitrogen removal under sole aerobic conditions. By using isotope ratio mass spectrometry, (15)N-labelled N2O and N2 were detected in aerobic batch cultures containing [Formula: see text], [Formula: see text] or [Formula: see text]. Strain YL converted [Formula: see text], [Formula: see text] and [Formula: see text] to produce more N2O than N2 in the presence of [Formula: see text]. An (15)N isotope tracing experiment confirmed that the nitrogen removal pathway of strain YL was heterotrophic nitrification-aerobic denitrification. The optimal treatment conditions for nitrogen removal were pH of 8, C/N ratio of 12, temperature of 25°C and shaking speed of 105 rpm. A continuous aerobic bioreactor inoculated with strain YL was developed. With an influent [Formula: see text] concentration of 90-200 mg/L, the [Formula: see text] removal efficiency ranged from 80% to 97% and the total nitrogen removal efficiency ranged from 72% to 95%. The nitrogen balance in the continuous bioreactor revealed that approximately 35-52% of influent [Formula: see text] was denitrified aerobically to form gaseous nitrogen. These findings show that the P. rettgeri strain YL has potential application in wastewater treatment for nitrogen removal under sole aerobic conditions. PMID:26824874

  19. Nitrification and aerobic denitrification in anoxic-aerobic sequencing batch reactor.

    Science.gov (United States)

    Alzate Marin, Juan C; Caravelli, Alejandro H; Zaritzky, Noemí E

    2016-01-01

    The aim of this study was to evaluate the feasibility of achieving nitrogen (N) removal using a lab-scale sequencing batch reactor (SBR) exposed to anoxic/aerobic (AN/OX) phases, focusing to achieve aerobic denitrification. This process will minimize emissions of N2O greenhouse gas. The effects of different operating parameters on the reactor performance were studied: cycle duration, AN/OX ratio, pH, dissolved oxygen concentration (DOC), and organic load. The highest inorganic N removal (NiR), close to 70%, was obtained at pH=7.5, low organic load (440mgCOD/(Lday)) and high aeration given by 12h cycle, AN/OX ratio=0.5:1.0 and DOC higher than 4.0mgO2/L. Nitrification followed by high-rate aerobic denitrification took place during the aerobic phase. Aerobic denitrification could be attributed to Tetrad-forming organisms (TFOs) with phenotype of glycogen accumulating organisms using polyhydroxyalkanoate and/or glycogen storage. The proposed AN/OX system constitutes an eco-friendly N removal process providing N2 as the end product. PMID:26512862

  20. Reforestation in southern China: revisiting soil N mineralization and nitrification after 8 years restoration.

    Science.gov (United States)

    Mo, Qifeng; Li, Zhi'an; Zhu, Weixing; Zou, Bi; Li, Yingwen; Yu, Shiqin; Ding, Yongzhen; Chen, Yao; Li, Xiaobo; Wang, Faming

    2016-01-01

    Nitrogen availability and tree species selection play important roles in reforestation. However, long-term field studies on the effects and mechanisms of tree species composition on N transformation are very limited. Eight years after tree seedlings were planted in a field experiment, we revisited the site and tested how tree species composition affects the dynamics of N mineralization and nitrification. Both tree species composition and season significantly influenced the soil dissolved organic carbon (DOC) and nitrogen (DON). N-fixing Acacia crassicarpa monoculture had the highest DON, and 10-mixed species plantation had the highest DOC. The lowest DOC and DON concentrations were both observed in Eucalyptus urophylla monoculture. The tree species composition also significantly affected net N mineralization rates. The highest rate of net N mineralization was found in A. crassicarpa monoculture, which was over twice than that in Castanopsis hystrix monoculture. The annual net N mineralization rates of 10-mixed and 30-mixed plantations were similar as that of N-fixing monoculture. Since mixed plantations have good performance in increasing soil DOC, DON, N mineralization and plant biodiversity, we recommend that mixed species plantations should be used as a sustainable approach for the restoration of degraded land in southern China. PMID:26794649

  1. Nitrogen removal characteristics of heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis C16

    Institute of Scientific and Technical Information of China (English)

    Yuxiang Liu; Yao Wang; Yi Li; Hua An; Yongkang Lv

    2015-01-01

    Alcaligenes faecalis C16 was found to have the ability to heterotrophically nitrify and aerobical y denitrify. In order to further understand its nitrogen removal ability and mechanism, the growth and ammonium removal response were investigated at different C/N ratios and ammonium concentrations in the medium with citrate and acetate as carbon source separately. Furthermore, experiments of nitrogen sources, production of nitrogen gas and enzyme assay were conducted. Results show that the bacterium converts NH4+-N and produces NH2OH during the growing phase and nitrite accumulation is its distinct metabolic feature. A. faecalis C16 is able to tolerate not only high ammonium concentration but also high C/N ratio, and the ammonium tolerance is associated with carbon source and C/N ratio. The nitrogen balance under different conditions shows that approximately 28%–45%of the initial ammonium is assimilated into the cells, 44%–60%is denitrified and several percent is converted to nitrification products. A. faecalis C16 cannot utilize hydroxylamine, nitrite or nitrate as the sole nitrogen source for growth. However, nitrate can be used when ammonium is simultaneously present in the medium. A possible pathway for nitrogen removal by C16 is suggested. The preliminary enzyme assay provides more evidence for this nitrogen removal pathway.

  2. Soil pH management by calcareous and siliceous minerals: effect on N2O yield in nitrification and denitrification

    Science.gov (United States)

    Nadeem, Shahid; Bakken, Lars; Dörsch, Peter

    2016-04-01

    Amelioration of soil pH by liming is necessary and common practice in vast areas of crop production. It is well known that pH is one of the most pervasive factors controlling rates and product stoichiometries in microbially mediated N transformations, including N2O emissions. While liming of acid soils appears to increase N2O reductase activity in denitrification (resulting in less N2O relative to N2), sudden pH raise may boost nitrification and hence N2O emission from ammonia oxidation. Thus, the net effect of liming on N2O emissions is not straightforward, which probably explains why soil pH management has not been embraced as a strategy for mitigating N2O emissions so far. Here we report laboratory incubations in which we determined potential rates and N2O yields in soils from an ongoing field experiment, comparing traditional calcareous limes (calcite, dolomite) with mafic minerals (olivine, different types of plagioclase). The experiment is in its second year, and shows strong pH increase (0.7-1.5, units) in plots with calcareous limes, a weak pH increase (~ 0.2 unit) in the olivine treatment and no measurable pH increase with the plagioclases. Potential nitrification rates correlated positively with effective soil pH as did the N2O yield, measured as N2O accumulation rate over NO2- + NO3- accumulation rate. The N2O yield increased in the order, control soils. Overall, the N2O yield from nitrification was quite low (0.09 - 0.17%). Potential denitrifications rates showed little response to pH increase (no C source added) but significantly lower N2O product ratios (N2O/(N2O + N2) with increasing pH in the order, calcite < dolomite < olivine < plagioclase < control. Given the overall low N2O yield of nitrification as compared to that of denitrification (10 - 100%), the observed increases in N2O yields of nitrification are unlikely to override a significant reduction in N2O production by denitrification under fluctuating oxic-anoxic conditions. The results will be

  3. Effects of acetylene at low concentrations on nitrification, mineralization and microbial biomass nitrogen concentrations in forest soils

    Institute of Scientific and Technical Information of China (English)

    ZHANG TengYu; XU XingKai; LUO XianBao; HAN Lin; WANG YingHong; PAN GenXing

    2009-01-01

    Temperate forest surface soils at the varying distances from main trunks (e.g., Pinus koraiensis and Quercus mongolica) were used to study the effects of acetylene (C2H2) at low concentrations on nitri-fication, mineralization and microbial biomass N concentrations of the soils, and to assess the contri-bution of heterotrophic nitrification to nitrous oxide (N2O) emissions from soils. The use of acetylene at partial pressures within a range from 10 to 100 Pa C2H2 in headspace gas gave a significant decrease in N2O emission at soil moisture of c. 45% water-filled porosity space, and the decrease was almost the same in each soil after exposure of C2H2 at low concentrations. Heterotrophic nitrification could ac-count for 21%-48% of total N2O emission from each soil; the contribution would increase with in-creasing distances from the Pinus koraiensis trunks rather than from the Quercus mongolica trunks.Under the experimental conditions, the use of C2H2 at low concentrations showed no significant influ-ence on soil microbial biomass N, net N mineralization and microbial respiration. However, 100 Pa C2H2in headspace gas could reduce carbon dioxide (CO2) emissions from soils. According to the rapid consumption of 10 Pa C2H2 by forest soils and convenience for laboratory incubations, 50 Pa C2H2 in headspace gas can be used to study the origin of N2O emissions from forest soils under aerobic con-ditions and the key associated driving mechanisms. The N2O and CO2 emissions from the soils at the same distances from the Quercus mongolica trunks were larger than those from the Pinus koraiensis trunks, and both emissions decreased as the distances from trunks increased. The stepwise regression analysis showed that 95% of the variability in soil CO2 emissions could be accounted for by the con-centrations of soil total C and water soluble organic C and soil pH, and that 72% of the variability in soil N2O emissions could be accounted for by the concentrations of soil total N

  4. Retention of titanium dioxide nanoparticles in biological activated carbon filters for drinking water and the impact on ammonia reduction.

    Science.gov (United States)

    Liu, Zhiyuan; Yu, Shuili; Park, Heedeung; Liu, Guicai; Yuan, Qingbin

    2016-06-01

    Given the increasing discoveries related to the eco-toxicity of titanium dioxide (TiO2) nanoparticles (NPs) in different ecosystems and with respect to public health, it is important to understand their potential effects in drinking water treatment (DWT). The effects of TiO2 NPs on ammonia reduction, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in biological activated carbon (BAC) filters for drinking water were investigated in static and dynamic states. In the static state, both the nitrification potential and AOB were significantly inhibited by 100 μg L(-1) TiO2 NPs after 12 h (p  0.05). In the dynamic state, different amounts of TiO2 NP pulses were injected into three pilot-scale BAC filters. The decay of TiO2 NPs in the BAC filters was very slow. Both titanium quantification and scanning electron microscope analysis confirmed the retention of TiO2 NPs in the BAC filters after 134 days of operation. Furthermore, the TiO2 NP pulses considerably reduced the performance of ammonia reduction. This study identified the retention of TiO2 NPs in BAC filters and the negative effect on the ammonia reduction, suggesting a potential threat to DWT by TiO2 NPs. PMID:26931341

  5. Membrane biofouling in a wastewater nitrification reactor: microbial succession from autotrophic colonization to heterotrophic domination

    KAUST Repository

    Lu, Huijie

    2015-10-22

    Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles.

  6. Aquarium nitrification revisited: Thaumarchaeota are the dominant ammonia oxidizers in freshwater aquarium biofilters.

    Science.gov (United States)

    Sauder, Laura A; Engel, Katja; Stearns, Jennifer C; Masella, Andre P; Pawliszyn, Richard; Neufeld, Josh D

    2011-01-01

    Ammonia-oxidizing archaea (AOA) outnumber ammonia-oxidizing bacteria (AOB) in many terrestrial and aquatic environments. Although nitrification is the primary function of aquarium biofilters, very few studies have investigated the microorganisms responsible for this process in aquaria. This study used quantitative real-time PCR (qPCR) to quantify the ammonia monooxygenase (amoA) and 16S rRNA genes of Bacteria and Thaumarchaeota in freshwater aquarium biofilters, in addition to assessing the diversity of AOA amoA genes by denaturing gradient gel electrophoresis (DGGE) and clone libraries. AOA were numerically dominant in 23 of 27 freshwater biofilters, and in 12 of these biofilters AOA contributed all detectable amoA genes. Eight saltwater aquaria and two commercial aquarium nitrifier supplements were included for comparison. Both thaumarchaeal and bacterial amoA genes were detected in all saltwater samples, with AOA genes outnumbering AOB genes in five of eight biofilters. Bacterial amoA genes were abundant in both supplements, but thaumarchaeal amoA and 16S rRNA genes could not be detected. For freshwater aquaria, the proportion of amoA genes from AOA relative to AOB was inversely correlated with ammonium concentration. DGGE of AOA amoA genes revealed variable diversity across samples, with nonmetric multidimensional scaling (NMDS) indicating separation of freshwater and saltwater fingerprints. Composite clone libraries of AOA amoA genes revealed distinct freshwater and saltwater clusters, as well as mixed clusters containing both freshwater and saltwater amoA gene sequences. These results reveal insight into commonplace residential biofilters and suggest that aquarium biofilters may represent valuable biofilm microcosms for future studies of AOA ecology. PMID:21858055

  7. Nitrification and its influence on biogeochemical cycles from the equatorial Pacific to the Arctic Ocean.

    Science.gov (United States)

    Shiozaki, Takuhei; Ijichi, Minoru; Isobe, Kazuo; Hashihama, Fuminori; Nakamura, Ken-Ichi; Ehama, Makoto; Hayashizaki, Ken-Ichi; Takahashi, Kazutaka; Hamasaki, Koji; Furuya, Ken

    2016-09-01

    We examined nitrification in the euphotic zone, its impact on the nitrogen cycles, and the controlling factors along a 7500 km transect from the equatorial Pacific Ocean to the Arctic Ocean. Ammonia oxidation occurred in the euphotic zone at most of the stations. The gene and transcript abundances for ammonia oxidation indicated that the shallow clade archaea were the major ammonia oxidizers throughout the study regions. Ammonia oxidation accounted for up to 87.4% (average 55.6%) of the rate of nitrate assimilation in the subtropical oligotrophic region. However, in the shallow Bering and Chukchi sea shelves (bottom ⩽67 m), the percentage was small (0-4.74%) because ammonia oxidation and the abundance of ammonia oxidizers were low, the light environment being one possible explanation for the low activity. With the exception of the shallow bottom stations, depth-integrated ammonia oxidation was positively correlated with depth-integrated primary production. Ammonia oxidation was low in the high-nutrient low-chlorophyll subarctic region and high in the Bering Sea Green Belt, and primary production in both was influenced by micronutrient supply. An ammonium kinetics experiment demonstrated that ammonia oxidation did not increase significantly with the addition of 31-1560 nm ammonium at most stations except in the Bering Sea Green Belt. Thus, the relationship between ammonia oxidation and primary production does not simply indicate that ammonia oxidation increased with ammonium supply through decomposition of organic matter produced by primary production but that ammonia oxidation might also be controlled by micronutrient availability as with primary production. PMID:26918664

  8. Aquarium nitrification revisited: Thaumarchaeota are the dominant ammonia oxidizers in freshwater aquarium biofilters.

    Directory of Open Access Journals (Sweden)

    Laura A Sauder

    Full Text Available Ammonia-oxidizing archaea (AOA outnumber ammonia-oxidizing bacteria (AOB in many terrestrial and aquatic environments. Although nitrification is the primary function of aquarium biofilters, very few studies have investigated the microorganisms responsible for this process in aquaria. This study used quantitative real-time PCR (qPCR to quantify the ammonia monooxygenase (amoA and 16S rRNA genes of Bacteria and Thaumarchaeota in freshwater aquarium biofilters, in addition to assessing the diversity of AOA amoA genes by denaturing gradient gel electrophoresis (DGGE and clone libraries. AOA were numerically dominant in 23 of 27 freshwater biofilters, and in 12 of these biofilters AOA contributed all detectable amoA genes. Eight saltwater aquaria and two commercial aquarium nitrifier supplements were included for comparison. Both thaumarchaeal and bacterial amoA genes were detected in all saltwater samples, with AOA genes outnumbering AOB genes in five of eight biofilters. Bacterial amoA genes were abundant in both supplements, but thaumarchaeal amoA and 16S rRNA genes could not be detected. For freshwater aquaria, the proportion of amoA genes from AOA relative to AOB was inversely correlated with ammonium concentration. DGGE of AOA amoA genes revealed variable diversity across samples, with nonmetric multidimensional scaling (NMDS indicating separation of freshwater and saltwater fingerprints. Composite clone libraries of AOA amoA genes revealed distinct freshwater and saltwater clusters, as well as mixed clusters containing both freshwater and saltwater amoA gene sequences. These results reveal insight into commonplace residential biofilters and suggest that aquarium biofilters may represent valuable biofilm microcosms for future studies of AOA ecology.

  9. Nitrification of archaeal ammonia oxidizers in a high- temperature hot spring

    Science.gov (United States)

    Chen, Shun; Peng, Xiaotong; Xu, Hengchao; Ta, Kaiwen

    2016-04-01

    The oxidation of ammonia by microbes has been shown to occur in diverse natural environments. However, the link of in situ nitrification activity to taxonomic identities of ammonia oxidizers in high-temperature environments remains poorly understood. Here, we studied in situ ammonia oxidation rates and the diversity of ammonia-oxidizing Archaea (AOA) in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N-NO3- pool dilution technique in the surface and bottom sediments were 4.80 and 5.30 nmol N g-1 h-1, respectively. Real-time quantitative polymerase chain reaction (qPCR) indicated that the archaeal 16S rRNA genes and amoA genes were present in the range of 0.128 to 1.96 × 108 and 2.75 to 9.80 × 105 gene copies g-1 sediment, respectively, while bacterial amoA was not detected. Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic Candidatus Nitrosocaldus yellowstonii, which represented the most abundant operational taxonomic units (OTU) in both surface and bottom sediments. The archaeal predominance was further supported by fluorescence in situ hybridization (FISH) visualization. The cell-specific rate of ammonia oxidation was estimated to range from 0.410 to 0.790 fmol N archaeal cell-1 h-1, higher than those in the two US Great Basin hot springs. These results suggest the importance of archaeal rather than bacterial ammonia oxidation in driving the nitrogen cycle in terrestrial geothermal environments.

  10. Practical identifiability of biokinetic parameters of a model describing two-step nitrification in biofilms.

    Science.gov (United States)

    Brockmann, D; Rosenwinkel, K-H; Morgenroth, E

    2008-10-15

    Parameter estimation and model calibration are key problems in the application of biofilm models in engineering practice, where a large number of model parameters need to be determined usually based on experimental data with only limited information content. In this article, identifiability of biokinetic parameters of a biofilm model describing two-step nitrification was evaluated based solely on bulk phase measurements of ammonium, nitrite, and nitrate. In addition to evaluating the impact of experimental conditions and available measurements, the influence of mass transport limitation within the biofilm and the initial parameter values on identifiability of biokinetic parameters was evaluated. Selection of parameters for identifiability analysis was based on global mean sensitivities while parameter identifiability was analyzed using local sensitivity functions. At most, four of the six most sensitive biokinetic parameters were identifiable from results of batch experiments at bulk phase dissolved oxygen concentrations of 0.8 or 5 mg O(2)/L. High linear dependences between the parameters of the subsets (KO2,AOB,muAOB) and (KO2,NOB,muNOB) resulted in reduced identifiability. Mass transport limitation within the biofilm did not influence the number of identifiable parameters but, in fact, decreased collinearity between parameters, especially for parameters that are otherwise correlated (e.g., muAOB) and KO2,AOB, or muNOB and KO2,NOB). The choice of the initial parameter values had a significant impact on the identifiability of two parameter subsets, both including the parameters muAOB and KO2,AOB. Parameter subsets that did not include the subsets muAOB and KO2,AOB or muNOB and KO2,NOB were clearly identifiable independently of the choice of the initial parameter values. PMID:18512262

  11. Biological Threats

    Science.gov (United States)

    ... Workplace Plans School Emergency Plans Main Content Biological Threats Biological agents are organisms or toxins that can ... for Disease Control and Prevention . Before a Biological Threat Unlike an explosion, a biological attack may or ...

  12. Adaptación y monitoreo de microorganismos en procesos de nitrificación en aguas residuales de la industria petrolera Adaptation and monitoring of microorganisms in petroleum industry wastewater nitrification processes

    Directory of Open Access Journals (Sweden)

    Díaz M.

    1998-12-01

    Full Text Available

    La remoción biológica de nitrógeno amoniacal se lleva a cabo en dos etapas sucesivas, la nitrificación y la desnitrificación. La nitrificación se estudió en un grupo de microorganismos aislados a partir de diferentes fuentes acuíferas: una ciénaga eutrificada y aguas residuales procedentes de dos plantas de tratamiento; una de tipo petroquímico y otra de origen doméstico. Los microorganismos se evaluaron en condiciones oxigénicas a 305K en un sistema semicontinuo. Se comprobó la buena adaptación de los microorganismos en aguas residuales de origen petroquímico en procesos de remoción de nitrógeno amoniacal.

    Biological removal of ammonia nitrogen is carried out in two successive stages, nitrification and denitrification. This work studied the nitrification process on microorganisms isolated from different aquifer sources: a eutrophicate pond and residual waters from two treatment plants (petrochemical and domestic

  13. [Start-up of a full-scale system for short-cut nitrification and Anammox in treatment of pharmaceutical wastewater].

    Science.gov (United States)

    Ding, Shuang; Zheng, Ping; Zhang, Zonghe; Lu, Huifeng; Zhang, Meng; Wu, Datian; Wu, Zegao

    2014-12-01

    In order to broaden the application area of the new nitrogen removal technology, a full-scale system for short-cut nitrification and anaerobic ammonium oxidation (Anammox) was investigated in the nitrogen removal from a strong-ammonium pharmaceutical wastewater. When the influent ammonium concentration was (430.40 ± 55.43) mg/L, ammonia removal efficiency was (81.75 ± 9.10)%. The short-cut nitrification and Anammox system could successfully remove nitrogen from the pharmaceutical wastewater. The start-up of short-cut nitrification system took about 74 d and the nitrite accumulation efficiency was (52.11 ± 9.13)%, the two-step mode using synthetic wastewater and actual wastewater was suitable for the start-up of short-cut nitrification system. The start-up of Anammox system took about 145 d and the maximum volumetric nitrogen removal rate was 6.35 kg N/(m3·d), dozens of times higher than those for the conventional nitrification-denitrification process. The strategy achieving Anammox sludge by self-growth and biocatalyst addition was suitable for the start-up of Anammox system. PMID:26016378

  14. Composition of ammonia-oxidizing archaea and their contribution to nitrification in a high-temperature hot spring

    Science.gov (United States)

    Chen, S.; Peng, X.-T.; Xu, H.-C.; Ta, K.-W.

    2015-10-01

    The oxidation of ammonia by microbes and associated organisms has been shown to occur in diverse natural environments. However, the contribution of ammonia-oxidizing archaea to nitrification in high-temperature environments remains unclear. Here, we studied in situ ammonia oxidation rates and the abundance of ammonia-oxidizing archaea (AOA) in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N-NO3- pool dilution technique in the surface sinter and bottom sediments were 4.8 and 5.3 nmol N g-1 h-1, respectively. Relative abundances of Crenarchaea in both samples were determined by fluorescence in situ hybridization (FISH). Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic "Candidatus Nitrosocaldus yellowstonii", which represented the most abundant operation taxonomic units (OTU) in both sediments. Furthermore, bacterial amoA was not detected in this study. Quantitative PCR (qPCR) indicated that AOA and 16S rRNA genes were present in the range of 2.75 to 9.80 × 105 and 0.128 to 1.96 × 108 gene copies g-1 sediment. The cell-specific nitrification rates were estimated to be in the range of 0.41 to 0.79 fmol N archaeal cell-1 h-1, which is consistent with earlier estimates in estuary environments. This study demonstrated that AOA were widely involved in nitrification in this hot spring. It further indicated the importance of archaea rather than bacteria in driving the nitrogen cycle in terrestrial geothermal environments.

  15. Composition of ammonia-oxidizing archaea and their contribution to nitrification in a high-temperature hot spring

    Directory of Open Access Journals (Sweden)

    S. Chen

    2015-10-01

    Full Text Available The oxidation of ammonia by microbes and associated organisms has been shown to occur in diverse natural environments. However, the contribution of ammonia-oxidizing archaea to nitrification in high-temperature environments remains unclear. Here, we studied in situ ammonia oxidation rates and the abundance of ammonia-oxidizing archaea (AOA in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N–NO3- pool dilution technique in the surface sinter and bottom sediments were 4.8 and 5.3 nmol N g−1 h−1, respectively. Relative abundances of Crenarchaea in both samples were determined by fluorescence in situ hybridization (FISH. Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic "Candidatus Nitrosocaldus yellowstonii", which represented the most abundant operation taxonomic units (OTU in both sediments. Furthermore, bacterial amoA was not detected in this study. Quantitative PCR (qPCR indicated that AOA and 16S rRNA genes were present in the range of 2.75 to 9.80 × 105 and 0.128 to 1.96 × 108 gene copies g−1 sediment. The cell-specific nitrification rates were estimated to be in the range of 0.41 to 0.79 fmol N archaeal cell−1 h−1, which is consistent with earlier estimates in estuary environments. This study demonstrated that AOA were widely involved in nitrification in this hot spring. It further indicated the importance of archaea rather than bacteria in driving the nitrogen cycle in terrestrial geothermal environments.

  16. Use of Aliphatic n-Alkynes To Discriminate Soil Nitrification Activities of Ammonia-Oxidizing Thaumarchaea and Bacteria

    OpenAIRE

    Taylor, Anne E.; Vajrala, Neeraja; Giguere, Andrew T.; Gitelman, Alix I; Arp, Daniel J.; Myrold, David D.; Sayavedra-Soto, Luis; Bottomley, Peter J

    2013-01-01

    Ammonia (NH3)-oxidizing bacteria (AOB) and thaumarchaea (AOA) co-occupy most soils, yet no short-term growth-independent method exists to determine their relative contributions to nitrification in situ. Microbial monooxygenases differ in their vulnerability to inactivation by aliphatic n-alkynes, and we found that NH3 oxidation by the marine thaumarchaeon Nitrosopumilus maritimus was unaffected during a 24-h exposure to ≤20 μM concentrations of 1-alkynes C8 and C9. In contrast, NH3 oxidation ...

  17. Artificial Intelligence for the Evaluation of Operational Parameters Influencing Nitrification and Nitrifiers in an Activated Sludge Process.

    Science.gov (United States)

    Awolusi, Oluyemi Olatunji; Nasr, Mahmoud; Kumari, Sheena; Bux, Faizal

    2016-07-01

    Nitrification at a full-scale activated sludge plant treating municipal wastewater was monitored over a period of 237 days. A combination of fluorescent in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qPCR) were used for identifying and quantifying the dominant nitrifiers in the plant. Adaptive neuro-fuzzy inference system (ANFIS), Pearson's correlation coefficient, and quadratic models were employed in evaluating the plant operational conditions that influence the nitrification performance. The ammonia-oxidizing bacteria (AOB) abundance was within the range of 1.55 × 10(8)-1.65 × 10(10) copies L(-1), while Nitrobacter spp. and Nitrospira spp. were 9.32 × 10(9)-1.40 × 10(11) copies L(-1) and 2.39 × 10(9)-3.76 × 10(10) copies L(-1), respectively. Specific nitrification rate (qN) was significantly affected by temperature (r 0.726, p 0.002), hydraulic retention time (HRT) (r -0.651, p 0.009), and ammonia loading rate (ALR) (r 0.571, p 0.026). Additionally, AOB was considerably influenced by HRT (r -0.741, p 0.002) and temperature (r 0.517, p 0.048), while HRT negatively impacted Nitrospira spp. (r -0.627, p 0.012). A quadratic combination of HRT and food-to-microorganism (F/M) ratio also impacted qN (r (2) 0.50), AOB (r (2) 0.61), and Nitrospira spp. (r (2) 0.72), while Nitrobacter spp. was considerably influenced by a polynomial function of F/M ratio and temperature (r (2) 0.49). The study demonstrated that ANFIS could be used as a tool to describe the factors influencing nitrification process at full-scale wastewater treatment plants. PMID:26906468

  18. Rotating biological contactors for wastewater treatment - A review

    OpenAIRE

    Hassard, Francis; Biddle, Jeremy R.; Cartmell, Elise; Jefferson, Bruce; Tyrrel, Sean F.; Stephenson, Tom

    2014-01-01

    Rotating biological contactors (RBCs) for wastewater treatment began in the 1970s. Removal of organic matter has been targeted within organic loading rates of up to 120 g m−2 d−1 with an optimum at around 15 g m−2 d−1 for combined BOD and ammonia removal. Full nitrification is achievable under appropriate process conditions with oxidation rates of up to 6 g m−2 d−1 reported for municipal wastewater. The RBC process has been adapted for denitrification with reported removal rates of up to 14 g...

  19. Partial Nitrification Realization and Stability at Normal Temperature%常温下短程硝化实现及稳定性试验研究

    Institute of Scientific and Technical Information of China (English)

    徐鹏; 何争光; 唐彦杰; 安国安

    2011-01-01

    以自配模拟氨氮废水为研究对象,在全程硝化污泥的基础上通过控制低曝气量和提高反应器进水pH值,在较低的DO质量浓度和较高pH值条件下完成了短程硝化污泥的驯化,系统中的NO2--N积累率稳定在95%以上;逐渐提高硝化阶段的曝气量、降低进水溶液的pH值,短程硝化过程没有被破坏;稳定的短程硝化系统改为定时控制,过度曝气6d后,NO2--N的积累率仅剩43.7%,硝化类型由短程硝化转变为全程硝化.%Taking artificially prepared high ammonia nitrogen wastewater as the research object, on the basis of full nitrification denitrification sludge, through controlling the aeration and the pH of influent water, short-cut nitrification-denitrification sludge with low DO and high pH was achieved. The nitrite nitrogen accumulation rate could above 95%. Then to gradually increase the aeration rate and lower the influent pH, the phenomenon that short-cut nitrification was not destroyed was found. When real time control was changed to fixed time control, on the 6th day after excessive aeration, accumulation of nitrite fell to 43.7% and the style of nitrification from short-cut nitrification changed to full nitrification with 6 d excessive aeration.

  20. Assessing nitrification and denitrification in a paddy soil with different water dynamics and applied liquid cattle waste using the 15N isotopic technique

    International Nuclear Information System (INIS)

    Using livestock wastewater for rice production in paddy fields can remove nitrogen and supplement the use of chemical fertilizers. However, paddy fields have complicated water dynamics owing to varying characteristics and would influence nitrogen removal through nitrification followed by denitrification. Quantification of nitrification and denitrification is of great importance in assessing the influence of water dynamics on nitrogen removal in paddy fields. In this study, nitrification and nitrate reduction rates with different water dynamics after liquid cattle waste application were evaluated, and the in situ denitrification rate was determined directly using the 15N isotopic technique in a laboratory experiment. A significant linear regression correlation between nitrification and the nitrate reduction rate was observed and showed different regression coefficients under different water dynamics. The regression coefficient in the continuously flooded paddy soil was higher than in the drained–reflooded paddy soil, suggesting that nitrate would be consumed faster in the flooded paddy soil. However, nitrification was limited and the maximum rate was only 13.3 μg N g−1 day−1 in the flooded paddy soil with rice plants, which limited the supply of nitrate. In contrast, the drained–reflooded paddy soil had an enhanced nitrification rate up to 56.8 μg N g−1 day−1, which was four times higher than the flooded paddy soil and further stimulated nitrate reduction rates. Correspondingly, the in situ denitrification rates determined directly in the drained–reflooded paddy soil ranged from 5 to 1035 mg N m−2 day−1, which was higher than the continuously flooded paddy soil (from 5 to 318 mg N m−2 day−1) during the vegetation period. The nitrogen removal through denitrification accounted for 38.9% and 9.9% of applied nitrogen in the drained–reflooded paddy soil and continuously flooded paddy soil, respectively. - Highlights: ► Nitrification and

  1. Shut-cut nitrification characteristics of aerobic granule in a sequencing batch airlift reactor at low temperature

    Institute of Scientific and Technical Information of China (English)

    BAO Rui-ling; YU Shui-li; ZUO Xing-tao; WANG Juan

    2009-01-01

    To investigate the shut-cut nitrification characteristics of aerobic granule, an aerobic granular se-quencing batch airlift reactor (AG-SBAR) was carried out with mixed carbon sources of sodium acetate and glu-cose at 10± 1℃. Results indicated that ammonia oxidizing bacteria was accumulated inside the aerobic gran-ules and the reactor performed stably with shut-cut nitrification for a long term at low temperature. During the stable operation period, the effluent ammonia nitrogen concentration was maintained at 13.6 mg/L without ni-trate and nitrite when the COD/N ratio was 20: 1. However, the effluent concentration of ammonia nitrogen was below 0. 5 mg/L with effluent nitrosation ratio of 96. 7% on average when the COD/N ratio was reduced to 15:1 and 10: 1. And the effluent phosphorus concentration was less than 0. 4 mg/L during the stable period with the sludge retention time of 30 d. The phosphorus removal efficiency was not strongly influenced by the adjust-ment of COD/N ratio in this experiment. The removal efficiencies for COD, NH4+-N and PO43--P were 91.3%-94. 6%, 97.9%-99. 7% and 97. 1%-99. 5%, respectively.

  2. [Rapid Start-up of Simultaneous Nitrification and Denitrification Coupled Phosphorus Removal Process and Its Performing Characteristics].

    Science.gov (United States)

    Leng, Lu; Xin, Xin; Lu, Hang; Tang, Ya-nan; Wan, Li-hua; Guo, Jun-yuan; Cheng, Qing-feng

    2015-11-01

    In this study, simultaneous nitrification and denitrification (SND) coupled Phosphorus removal process through gradually decreasing DO concentration was investigated by treating wastewater with a low COD/TN ratio (C/N = 3 : 1-4: 1) in a sequencing batch reactor (SBR) inoculated with aerobic granular sludge (AGS). Successful SND coupled Phosphorus phenomenon occurred after 20d at the DO concentration of 0.50-1.0 mg x L(-1). In the following 40 days, the average removal rates of COD, NH4(+) -N, TN and TP were 84.84% , 93.51%, 77.06% and 85.69%, and the NO3(-) -N and NO2(-) -N average accumulations in the effluent were only 4.01 mg x L(-1) and 3.17 mg x L(-1), respectively. The AGS had complete forms and good settling performances, and the sludge volume index (SVI) was about 55.22 mL x g(-1) at the end of starting-up stage. The results of different nitrogen sources showed that the removal rate of TN was in the order of NH4(+) -N > NO2(-) -N > NO3(-) -N, and the removal rate of TP was in the order of NO3(-) -N > NO2(-) -N > NH4(+) -N. The nitrogen and phosphorus removal of wastewater were mainly realized by simultaneous nitrification and denitrification and denitrifying phosphorus removal, respectively. PMID:26911007

  3. The effects of different seeding ratios on nitrification performance and biofilm formation in marine recirculating aquaculture system biofilter.

    Science.gov (United States)

    Zhu, Songming; Shen, Jiazheng; Ruan, Yunjie; Guo, Xishan; Ye, Zhangying; Deng, Yale; Shi, Mingming

    2016-07-01

    Rapid start-up of biofilter is essential for intensive marine recirculating aquaculture system (RAS) production. This study evaluated the nitrifying biofilm formation using mature biofilm as an inoculum to accelerate the process in RAS practice. The effects of inoculation ratios (0-15 %) on the reactor performance and biofilm structure were investigated. Complete nitrification was achieved rapidly in reactors with inoculated mature biofilm (even in 32 days when 15 % seeding ratio was applied). However, the growth of target biofilm on blank carrier was affected by the mature biofilm inoculated through substrate competition. The analysis of extracellular polymeric substance (EPS) and nitrification rates confirmed the divergence of biofilm cultivation among reactors. Besides, three N-acyl-homoserine lactones (AHLs) were found in the process, which might regulate the activities of biofilm. Multivariate analysis based on non-metric multidimensional scaling (nMDS) also indicated the great roles of AHLs and substrate supply which might fundamentally determine varied cultivation performance on target biofilm. PMID:27068911

  4. Characteristics of pellets with immobilized activated sludge and its performance in increasing nitrification in sequencing batch reactors at low temperatures.

    Science.gov (United States)

    Dong, Wenjie; Lu, Guang; Yan, Li; Zhang, Zhenjia; Zhang, Yalei

    2016-04-01

    Immobilized pellets obtained by means of entrapping activated sludge in waterborne polyurethane were successfully adapted in ammonium (NH4(+)-N) synthetic wastewater. Its physicochemical characteristics were determined using scanning electron microscope, pyrosequencing, and microelectrodes, and its influence on the nitrification process in sequencing batch reactors (SBRs) at low temperatures was evaluated. A large number of rod-shaped bacteria were observed on the surface of the immobilized pellet, in which Rudaea spp. (Xanthomonadaceae family) was an important bacterial component (23.44% of the total bacteria). The oxygen uptake rate of immobilized pellets reached 240.83±15.59mgO2/(L·hr), and the oxygen was primarily consumed by the bacteria on the pellet surfaces (0-600μm). The dosing of the pellets (30mL/L) into an SBR significantly improved the nitrification efficiency at low temperatures of 7-11°C, achieving an average NH4(+)-N removal of 84.09%, which is higher than the removal of 67.46% observed for the control group. PMID:27090712

  5. Acceleration of aged-landfill stabilization by combining partial nitrification and leachate recirculation: a field-scale study.

    Science.gov (United States)

    Chung, Jinwook; Kim, Seungjin; Baek, Seungcheon; Lee, Nam-Hoon; Park, Seongjun; Lee, Junghun; Lee, Heechang; Bae, Wookeun

    2015-03-21

    Leachate recirculation for rapid landfill stabilization can result in the accumulation of high-strength ammonium. An on-site sequencing batch reactor (SBR) was therefore, applied to oxidize the ammonium to nitrite, which was then recirculated to the landfill for denitrification to nitrogen gas. At relatively higher ammonium levels, nitrite accumulated well in the SBR; the nitrite was denitrified stably in the landfill, despite an insufficient biodegradable carbon source in the leachate. As the leachate was recirculated, the methane and carbon dioxide contents produced from the landfill fluctuated, implying that the organic acids and hydrogen produced in the acid production phase acted as the carbon source for denitrification in the landfill. Leachate recirculation combined with ex-situ partial nitrification of the leachate may enhance the biodegradation process by: (a) removing the nitrogen that is contained with the leachate, and (b) accelerating landfill stabilization, because the biodegradation efficiency of landfill waste is increased by supplying sufficient moisture and its byproducts are used as the carbon source for denitrification. In addition, partial nitrification using an SBR has advantages for complete denitrification in the landfill, since the available carbon source is in short supply in aged landfills. PMID:25531070

  6. Achieving and maintaining biological nitrogen removal via nitrite under normal conditions

    Institute of Scientific and Technical Information of China (English)

    CUI You-wei; PENG Yong-zhen; GAN Xiang-qing; YE Liu; WANG Ya-yi

    2005-01-01

    The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor(SBR)activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride(NaCl) to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.

  7. Phosphate limitation in biological rapid sand filters used to remove ammonium from drinking water

    DEFF Research Database (Denmark)

    Lee, Carson Odell; Albrechtsen, Hans-Jørgen; Smets, Barth F.;

    2013-01-01

    Removing ammonium from drinking water is important for maintaining biological stability in distribution systems. This is especially important in regions that do not use disinfectants in the treatment process or keep a disinfectant residual in the distribution system. Problems with nitrification can...... occur with increased ammonium loads caused by seasonal or operational changes and can lead to extensive periods of elevated ammonium and nitrite concentrations in the effluent. One possible cause of nitrification problems in these filters maybe due to phosphate limitation. This was investigated using a...... pilot scale sand column which initial analysis confirmed performed similarly to the full scale filters. Long term increased ammonium loads were applied to the pilot filter both with and without phosphate addition. Phosphate was added at a concentration of 0.5 mg PO4-P/L to ensure that it was not the...

  8. Removal of nitrogen and organic matter in a submerged-membrane bioreactor operating in a condition of simultaneous nitrification and denitrification

    Directory of Open Access Journals (Sweden)

    Izabela Major Barbosa

    2016-04-01

    Full Text Available This study evaluated the removal of nitrogen and organic matter in a membrane bioreactor system operating in a condition of simultaneous nitrification and denitrification controlled by intermittent aeration. A submerged-membrane system in a bioreactor was used in a pilot scale to treat domestic wastewater. The dissolved oxygen concentration was maintained between 0.5 and 0.8 mg L-1. The concentration of the mixed liquor suspended solids (MLSS in the system ranged from 1 to 6 g L-1. The system efficiency was evaluated by the removal efficiency of organic matter, quantified by Chemical Oxygen Demand (COD, Biochemical Oxygen Demand (BOD5 and Total Organic Carbon (TOC. Nitrogen removal was assessed by quantifying Total Kjeldahl Nitrogen (TKN and ammonia nitrogen. During the system start-up, the removal efficiencies of COD and NTK were around 90% and 80%, respectively. After the simultaneous nitrification and denitrification (SND conditions were established, the removal efficiencies of COD and NTK were 70% and 99%, respectively. These results showed that sewage treatment with the membrane bioreactor (MBR system, operating with simultaneous nitrification and denitrification conditions, was able to remove organic matter and promote nitrification and denitrification in a single reactor, producing a high-quality permeate.

  9. Effective mitigation of nitrate leaching and nitrous oxide emissions in intensive vegetable production systems using a nitrification inhibitor, dicyandiamide

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Min; Sun, Xuecheng; Hu, Chengxiao; Tan, Qiling; Zhao, Changsheng [Huazhong Agricultural Univ., Wuhan (China). Key Lab. of Subtropical Agricultural Resources and Environment; Di, Hong J. [Lincoln Univ., Christchurch (New Zealand). Center for Soil and Environment Research

    2011-07-15

    Vegetable production is one of the most intensive agricultural systems with high rates of nitrogen (N) fertilizer use and irrigation, conditions conducive for nitrate (NO{sub 3}{sup -}) leaching, and nitrous oxide (N{sub 2}O) emissions. The objective of this study was to determine the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in decreasing NO{sub 3}{sup -} leaching and N{sub 2}O emissions in vegetable production systems. Twenty-four undisturbed soil monolith lysimeters (610 mm in diameter; 700 mm in depth; surface area, 0.29 m{sup 2}) with two different soils, Huangzongrang (alfisol) and Chaotu (fluvisols), were collected and installed in a field lysimeter facility in Central China under irrigated vegetable production conditions. Urea fertilizer was applied at 650 kg N ha{sup -1}, and DCD was applied at 10 kg ha{sup -1} to the lysimeters planted with three kinds of vegetables (capsicum, Capsicum annuum L.; amaranth, Amaranthus mangostanus L.; radish, Raphanus sativus L.). The results showed that DCD reduced NO3- leaching by 58.5% and 36.2% and N{sub 2}O emissions factor by 83.8% and 72.7% in the two soils. The average NO{sub 3}{sup -}-N concentration in the drainage water was decreased from 4.9 mg NL{sup -1} to 2.3 mg NL{sup -1} and from 4.4 mg NL{sup -1} to 3.3 mg NL{sup -1}, in the Huangzongrang and Chaotu soils, respectively. In addition to the environmental benefits, the use of DCD also increased the yields of capsicum and radish in alfisol soil significantly (P < 0.01); only the amaranth yield in fluvisol soil was declined (P < 0.01), and the other vegetables yields were not affected. Total N concentrations of the three vegetables were increased significantly (P < 0.01) with the application of DCD with urea compared with urea alone. These results showed that the nitrification inhibitor DCD has the potential to significantly reduce NO{sub 3}{sup -} leaching and N{sub 2}O emissions and to make vegetable farming more environmentally

  10. Adenosine triphosphate inhibition of yeast trehalase.

    Science.gov (United States)

    Panek, A D

    1969-09-01

    Yeast trehalase has been found to be inhibited non-competitively by adenosine triphosphate. Such a biological control could explain the accumulation of trehalose during the stationary phase of the growth curve. PMID:5370287

  11. Analysis of Microbial Communities in Biofilms from CSTR-Type Hollow Fiber Membrane Biofilm Reactors for Autotrophic Nitrification and Hydrogenotrophic Denitrification.

    Science.gov (United States)

    Shin, Jung-Hun; Kim, Byung-Chun; Choi, Okkyoung; Kim, Hyunook; Sang, Byoung-In

    2015-10-28

    Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH4(+)-N/m(3)/d and 0.10-0.21 kg NO3(-)-N/m(3)/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH4(+) or NO3(-) loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs. PMID:26095385

  12. Biomass characteristics and simultaneous nitrification-denitrification under long sludge retention time in an integrated reactor treating rural domestic sewage.

    Science.gov (United States)

    Gong, Lingxiao; Jun, Li; Yang, Qing; Wang, Shuying; Ma, Bin; Peng, Yongzhen

    2012-09-01

    In this work, a novel integrated reactor incorporating anoxic fixed bed biofilm reactor (FBBR), oxic moving bed biofilm reactor (MBBR) and settler sequentially was proposed for nitrogen removal from rural domestic sewage. For purposes of achieving high efficiency, low costs and easy maintenance, biomass characteristics and simultaneous nitrification-denitrification (SND) were investigated under long sludge retention time during a 149-day period. The results showed that enhanced SND with proportions of 37.7-42.2% tapped the reactor potentials of efficiency and economy both, despite of C/N ratio of 2.5-4.0 in influent. TN was removed averagely by 69.3% at least, even under internal recycling ratio of 200% and less proportions of biomass assimilation (anoxic stir. Furthermore, biomass with low observed heterotrophic yields (0.053 ± 0.035 g VSS/g COD) and VSS/TSS ratio (MBBR, simplified wasted sludge disposal. PMID:22750493

  13. Discrepant membrane fouling of partial nitrification and anammox membrane bioreactor operated at the same nitrogen loading rate.

    Science.gov (United States)

    Niu, Zhao; Zhang, Zuotao; Liu, Sitong; Miyoshi, Taro; Matsuyama, Hideo; Ni, Jinren

    2016-08-01

    In this study, two times more serious membrane fouling was found in anammox membrane bioreactor, compared to partial nitrification membrane bioreactor (PN-MBR) operated at the same nitrogen loading rate. By protein, polysaccharide, amino acids and functional groups analysis, it was found that the discrepancy in membrane fouling was virtually due to the difference in microbial products of nitrifiers and anammox bacteria. Protein and polysaccharide were main foulants on membrane surface; meanwhile theirs content and ratio in the EPS, supernatant and membrane surface were significantly different in PN-MBR and anammox-MBR. The anammox metabolism products contained much more hydrophobic organics, hydrophobic amino acids, and hydrophobic functional groups than nitrifiers. A mass of anammox bacteria as well as hydrophobic metabolism products deposited on the hydrophobic membrane surface and formed serious fouling. In further, hydrophilic modification is more urgently needed to mitigate membrane fouling when running anammox-MBR, than PN-MBR. PMID:27209455

  14. Nitrogen removal influence factors in A/O process and decision trees for nitrification/denitrification system

    Institute of Scientific and Technical Information of China (English)

    MA Yong; PENG Yong-zhen; WANG Shu-ying; WANG Xiao-lian

    2004-01-01

    In order to improve nitrogen removal in anoxic/oxic(A/O) process effectively for treating domestic wastewaters, the influence factors, DO(dissolved oxygen), nitrate recirculation, sludge recycle, SRT(solids residence time), influent COD/TN and HRT(hydraulic retention time) were studied. Results indicated that it was possible to increase nitrogen removal by using corresponding control strategies, such as, adjusting the DO set point according to effluent ammonia concentration; manipulating nitrate recirculation flow according to nitrate concentration at the end of anoxic zone. Based on the experiments results, a knowledge-based approach for supervision of the nitrogen removal problems was considered, and decision trees for diagnosing nitrification and denitrification problems were built and successfully applied to A/O process.

  15. Evaluation of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) for N2O mitigation after grassland cultivation

    DEFF Research Database (Denmark)

    Kong, Xianwang

    2016-01-01

    soil N availability in combination with locally high O2-demand due to residue decomposition, emissions of potent greenhouse gas nitrous oxide (N2O) may increase. So far no specific strategy has been considered to mitigate soil N2O emissions following grassland cultivation. In this thesis, four inter...... grasslands in crop rotations. At the transition phase, the mineralization of grass and clover residues incorporated by grassland cultivation can supply nitrogen to a succeeding crop; however, the plant N-uptake is low for several weeks at the early growth stage. During this period, as a result of increasing......-linked experiments including both simulation and field study were performed to evaluate a potential mitigation strategy for residue-induced N2O emissions. A nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) was applied on grassland by spraying shortly before cultivation. The cultivation was done either...

  16. Impacts of addition of natural zeolite or a nitrification inhibitor on antibiotic resistance genes during sludge composting.

    Science.gov (United States)

    Zhang, Junya; Chen, Meixue; Sui, Qianwen; Tong, Juan; Jiang, Chao; Lu, Xueting; Zhang, Yuxiu; Wei, Yuansong

    2016-03-15

    Composting is commonly used for the treatment and resource utilization of sewage sludge, and natural zeolite and nitrification inhibitors can be used for nitrogen conservation during sludge composting, while their impacts on ARGs control are still unclear. Therefore, three lab-scale composting reactors, A (the control), B (natural zeolite addition) and C (nitrification inhibitor addition of 3,4-dimethylpyrazole phosphate, DMPP), were established. The impacts of natural zeolite and DMPP on the levels of ARGs were investigated, as were the roles that heavy metals, mobile genetic elements (MGEs) and the bacterial community play in ARGs evolution. The results showed that total ARGs copies were enriched 2.04 and 1.95 times in reactors A and C, respectively, but were reduced by 1.5% in reactor B due to the reduction of conjugation and co-selection of heavy metals caused by natural zeolite. Although some ARGs (blaCTX-M, blaTEM, ermB, ereA and tetW) were reduced by 0.3-2 logs, others (ermF, sulI, sulII, tetG, tetX, mefA and aac(6')-Ib-cr) increased by 0.3-1.3 logs after sludge composting. Although the contributors for the ARGs profiles in different stages were quite different, the results of a partial redundancy analysis, Mantel test and Procrustes analysis showed that the bacterial community was the main contributor to the changes in ARGs compared to MGEs and heavy metals. Network analysis determined the potential host bacteria for various ARGs and further confirmed our results. PMID:26808292

  17. Effect of forest thinning on soil net nitrogen mineralization and nitrifi-cation in a Cryptomeria japonica plantation in Taiwan

    Institute of Scientific and Technical Information of China (English)

    Shunyao Zhuang; Jin Wang; Xiao Sun; Mingkuang Wang

    2014-01-01

    We investigated the effect of forest thinning on soil nitrogen mineralization, nitrification and transformation in a Cryptomeria japoni-ca plantation at high elevation to provide basic data for forest manage-ment. We chose four study plots for control, light, medium and heavy thinning treatment, and three sub-plots for buried bag studies at similar elevations in each treatment plot to measure the net N mineralization and nitrification rates in situ. The contents of soil inorganic N (ammonium and nitrate) were similar between treatments, but all varied with season, reaching maxima in September 2003 and 2004. The seasonal maximum net Nmin rates after four treatments were 0.182, 0.246, 0.303 and 0.560 mg⋅kg-1⋅d-1 in 2003, and 0.242,0.258,0.411 and 0.671 mg⋅kg-1⋅d-1in 2004, respectively. These estimates are approximate with the lower annual rates of N mineralization for this region. Forest thinning can enhance net N mineralization and microbial biomass carbon. The percentage of annual rates of Nmin for different levels of forest thinning compared with the control plot were 13.4%, 59.8%and 154.2%in 2003, and 0.1%, 58.8%and 157.7%in 2004 for light, medium, and heavy thinning, respectively. These differences were related to soil moisture, temperature, precipita-tion, and soil and vegetation types. Well-planned multi-site comparisons, both located within Taiwan and the East-Asia region, could greatly im-prove our knowledge of regional patterns in nitrogen cycling.

  18. Nitrogen cycling in the Southern Ocean Kerguelen Plateau area: evidence for significant surface nitrification from nitrate isotopic compositions

    Directory of Open Access Journals (Sweden)

    F. Dehairs

    2014-09-01

    Full Text Available This paper presents whole water column data for nitrate N, O isotopic composition for the Kerguelen Plateau area and the basin extending east of the island, aiming at understanding the N-cycling in this naturally iron fertilized area that is characterized by large re-current phytoplankton blooms. The KEOPS 2 expedition (October–November 2011 took place in spring season and complements knowledge gathered during an earlier summer expedition to the same area (KEOPS 1, February–March 2005. As noted by others a remarkable condition of the system is the moderate consumption of nitrate over the season (nitrate remains > 20 μM while silicic acid becomes depleted, suggesting significant recycling of nitrogen. Nitrate isotopic signatures in the upper water column do mimic this condition, with surprising overlap of spring and summer regressions of δ18ONO3 vs. δ15NNO3 isotopic compositions. These regressions obey rather closely the 18ϵ/15ϵ discrimination expected for nitrate uptake (18ϵ/15ϵ = 1, but regression slopes as large as 1.6 were observed for the mixed layer above the Kerguelen Plateau. A preliminary mass balance calculation for the early bloom period points toward significant nitrification occurring in the mixed layer and which could account for up to 80 % of nitrate uptake above the Kerguelen Plateau. A further finding concerns deep ocean low δ18ONO3 values (< 2‰ underlying high chlorophyll waters at the Polar Front Zone and which cannot be explained by remineralisation and nitrification of the local particulate nitrogen flux, which is too small in magnitude. However, the studied area is characterised by a complex recirculation pattern that would keep deep waters in the area and could impose a seasonally integrated signature of surface water processes on the deep waters.

  19. A novel stoichiometries methodology to quantify functional microorganisms in simultaneous (partial) nitrification-endogenous denitrification and phosphorus removal (SNEDPR).

    Science.gov (United States)

    Wang, Xiaoxia; Wang, Shuying; Zhao, Ji; Dai, Xian; Li, Baikun; Peng, Yongzhen

    2016-05-15

    Although efficient removal of carbon (C), nitrogen (N) and phosphorous (P) from wastewater with low C/N ratio was achieved in anaerobic/aerobic simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) systems, the removal pathways and metabolic transformations in this complex system are unclear. This work targeted at developing the stoichiometric models for denitrifying glycogen organisms (DGAOs) via nitrite and nitrate (DGAONi and DGAONa), and demonstrating a novel methodology to quantify diverse functional microorganisms (e.g. ammonia and nitrite oxidizing bacteria, aerobic phosphorus accumulating organisms (APAOs), denitrifying PAOs (DPAOs) and aerobic GAOs (AGAOs)) for the removal of C, N and P. The results showed that the anaerobic intracellular carbon storage (CODintra) was mainly accomplished by GAOs, and PAOs were only responsible for about 40% of CODintra through a stable P release. At the aerobic stage, 84.9% of P was removed by APAOs with 15.1% left by DPAOs, while 64.6% of N was removed by DGAOs (45.8% by DGAONi and 18.8% by DGAONa) with 18.1% by DPAOs and 17.3% by bacterial growth. High proportion of N removal via nitrite (partial nitrification-endogenous denitrification) (71%) saved 7.3% aeration and 38% intracellular carbon demand. However, AGAOs still activated well at the aerobic intercellular carbon consumption, which limited the further improvement of N removal efficiency. By elucidating the nutrient removal pathways among diverse functional microorganisms, the methodology developed in this study could accelerate the nutrient removal in the SNEDPR process. PMID:27016642

  20. Contour Detection Operators Based on Surround Inhibition

    NARCIS (Netherlands)

    Grigorescu, Cosmin; Petkov, Nicolai; Westenberg, Michel A.

    2003-01-01

    We propose a biologically motivated computational step, called non-classical receptive field (non-CRF) inhibition, to improve contour detection in images of natural scenes. We augment a Gabor energy operator with non-CRF inhibition. The resulting contour operator responds strongly to isolated lines,

  1. Treatment technologies for ammonia in liquid manure: nitrification/denitrification and anammox based deammonification

    Science.gov (United States)

    Biological treatment is regarded as the most efficient and economically feasible method available for removal of ammonia from wastewater. Its use for animal wastewater required development of new systems and methods that could handle the higher-strength characteristics of liquid manure. The discover...

  2. Bacteria, not archaea, restore nitrification in a zinc-contaminated soil

    NARCIS (Netherlands)

    Mertens, J.; Broos, K.; Wakelin, S.A.; Kowalchuk, G.A.; Springael, D.; Smolders, E.

    2009-01-01

    Biological ammonia oxidation had long been thought to be mediated solely by discrete clades of - and -proteobacteria (ammonia-oxidizing bacteria; AOB). However, ammonia-oxidizing Crenarchaeota (ammonia-oxidizing archaea; AOA) have recently been identified and proposed to be the dominant agents of am

  3. 限制曝气实现常温条件下生活污水短程硝化%Partial Nitrification from Domestic Wastewater by Aeration Control at Ambient Temperature

    Institute of Scientific and Technical Information of China (English)

    彭永臻; 高守有; 王淑莹; 白璐

    2007-01-01

    The objective of this paper was to examine the feasibility of partial nitrification from raw domestic wastewater at ambient temperature by aeration control only. Airflow rate was selected as the sole operational parameter. A 14L sequencing batch reactor was operated at 23℃ for 8 months, with an input of domestic wastewater.deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate and that this system showed relatively stability at higher airflow rate independent of pH and temperature. About 50% of influent total nitrogen was eliminated coupling with partial nitrification, taking the advantage of low DO during the reaction.

  4. From Earth to Space: Application of Biological Treatment for the Removal of Ammonia from Water

    Science.gov (United States)

    Pickering, Karen; Adam, Niklas; White, Dawn; Ghosh, Amlan; Seidel, Chad

    2014-01-01

    Managing ammonia is often a challenge in both drinking water and wastewater treatment facilities. Ammonia is unregulated in drinking water, but its presence may result in numerous water quality issues in the distribution system such as loss of residual disinfectant, nitrification, and corrosion. Ammonia concentrations need to be managed in wastewater effluent to sustain the health of receiving water bodies. Biological treatment involves the microbiological oxidation of ammonia to nitrate through a two-step process. While nitrification is common in the environment, and nitrifying bacteria can grow rapidly on filtration media, appropriate conditions, such as the presence of dissolved oxygen and required nutrients, need to be established. This presentation will highlight results from two ongoing research programs - one at NASA's Johnson Space Center, and the other at a drinking water facility in California. Both programs are designed to demonstrate nitrification through biological treatment. The objective of NASA's research is to be able to recycle wastewater to potable water for spaceflight missions. To this end, a biological water processor (BWP) has been integrated with a forward osmosis secondary treatment system (FOST). Bacteria mineralize organic carbon to carbon dioxide as well as ammonia-nitrogen present in the wastewater to nitrogen gas, through a combination of nitrification and denitrification. The effluent from the BWP system is low in organic contaminants, but high in total dissolved solids. The FOST system, integrated downstream of the BWP, removes dissolved solids through a combination of concentration-driven forward osmosis and pressure driven reverse osmosis. The integrated system testing planned for this year is expected to produce water that requires only a polishing step to meet potable water requirements for spaceflight. The pilot study in California is being conducted on Golden State Water Company's Yukon wells that have hydrogen sulfide odor

  5. Systematic model development for partial nitrification of landfill leachate in a SBR

    DEFF Research Database (Denmark)

    Ganigue, R.; Volcke, E.I.P.; Puig, S.;

    2010-01-01

    . Following a systematic procedure, the model was successfully constructed, calibrated and validated using data from short-term (one cycle) operation of the PN-SBR. The evaluation of the model revealed a good fit to the main physical-chemical measurements (ammonium, nitrite, nitrate and inorganic carbon......), confirmed by statistical tests. Good model fits were also obtained for pH, despite a slight bias in pH prediction, probably caused by the high salinity of the leachate. Future work will be addressed to the model-based evaluation of the interaction of different factors (aeration, stripping, pH, inhibitions...

  6. Factors impacting biotransformation kinetics of trace organic compounds in lab-scale activated sludge systems performing nitrification and denitrification

    Energy Technology Data Exchange (ETDEWEB)

    Su, Lijuan; Aga, Diana [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Chandran, Kartik [Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027 (United States); Khunjar, Wendell O., E-mail: wkhunjar@hazenandsawyer.com [Hazen and Sawyer P.C., Fairfax, VA 22030 (United States)

    2015-01-23

    Highlights: • We examined TOrC biotransformation kinetics in nitrifying and denitrifying reators. • TOrC biotransformation was linked to heterotrophic and autotrophic activity. • TOrC biotransformation rates were not sensitive to the initial TOrC concentration. • Readily biodegradable organic matter suppressed TOrC biotransformation rates. - Abstract: To predict TOrC fate in biological activated sludge systems, there is a need to accurately determine TOrC biodegradation kinetics in mixed microbial cultures. Short-term batch tests with salicylic acid, 17α-ethinylestradiol, nonylphenol, trimethoprim and carbamazepine were conducted with lab-scale activated sludge cultures in which the initial TOrC concentration (1 mg/L and 0.0005 mg/L) and readily biodegradable substrate concentrations were varied. The results indicate that pseudo-first order kinetic estimates of TOrC are not sensitive (p > 0.05) to the initial TOrC concentration as long as the initial TOrC concentration (S{sub 0}) to biomass (X{sub 0}) ratio (on COD basis) is below 2 × 10{sup −3}. The presence of readily biodegradable organic matter suppresses TOrC biotransformation rates under nitrifying and denitrifying conditions, and this impact can be adequately described using a reversible non-competitive inhibition equation. These results demonstrate the importance of closely mimicking parent reactor conditions in batch testing because biotransformation parameters are impacted by in-situ carbon loading and redox conditions.

  7. Respirometry applied for biological nitrogen removal process; Aplicacion de la respirometria al tratamiento biologico para la eliminacion del nitrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, E.

    2004-07-01

    In waste water treatment plants, the Biological Nitrogen Removal (BNR) has acquired a fundamental importance. The BNR processes are Nitrification ( aerobic) and Denitrification (anoxic). Since both processes are carried on living microorganisms, a lack of their bioactivity information might cause serious confusion about their control criteria and following up purposes. For this reason, the Re spirometry applied to those processes has reached an important role by getting an essential information in a timely manner through respiration rate measurements in static and dynamic modes and applications such as AUR (Ammonium Uptake Rate), Nitrification Capacity. RBCOD (Readily Biodegradable COD) as well as AUR related to SRT (Sludge age), RBCOD related to NUR (Specific Nitrate Uptake Rate) and others. By other side in this article we have introduced a not very well known applications related to denitrification, about the methanol acclimatization and generated bioactivity. (Author) 6 refs.

  8. Interactions entre processus microbiens, cycle des nutriments et fonctionnement du couvert herbacé: cas de la nitrification dans les sols d'une savane humide de Côte d'Ivoire sous couvert à Hyparrhenia diplandra.

    OpenAIRE

    Lata, Jean-Christophe

    1999-01-01

    Soil nitrification is an important process that partly controls nitrogen availability for plants and nitrogen conservation at ecosystem level. This process is particularly critical in nutrient-poor systems like the wet savanna of Lamto (West Africa) where nitrogen is considered as the major factor limiting primary production. Savanna facies dominated by the grass Hyparrhenia diplandra are known to exhibit low levels of nitrification and thus avoid nitrate losses. We used high/low nitrificatio...

  9. Nitrification-driven forms of nitrogen metabolism in microbial mat communities thriving along an ammonium-enriched subsurface geothermal stream

    Science.gov (United States)

    Nishizawa, Manabu; Koba, Keisuke; Makabe, Akiko; Yoshida, Naohiro; Kaneko, Masanori; Hirao, Shingo; Ishibashi, Jun-ichiro; Yamanaka, Toshiro; Shibuya, Takazo; Kikuchi, Tohru; Hirai, Miho; Miyazaki, Junichi; Nunoura, Takuro; Takai, Ken

    2013-07-01

    We report here the concurrence and interaction among forms of nitrogen metabolism in thermophilic microbial mat communities that developed in an ammonium-abundant subsurface geothermal stream. First, the physical and chemical conditions of the stream water at several representative microbial mat habitats (including upper, middle and downstream sites) were characterized. A thermodynamic calculation using these physical and chemical conditions predicted that nitrification consisting of ammonia and nitrite oxidations would provide one of the largest energy yields of chemolithotrophic metabolisms. Second, near-complete prokaryotic 16S rRNA gene clone analysis was conducted for representative microbial mat communities at the upper, middle and downstream sites. The results indicated a dynamic shift in the 16S rRNA gene phylotype composition through physical and chemical variations of the stream water. The predominant prokaryotic components varied from phylotypes related to hydrogeno (H2)- and thio (S)-trophic Aquificales, thermophilic methanotrophs and putative ammonia-oxidizing Archaea (AOA) located upstream (72 °C) to the phylotypes affiliated with putative AOA and nitrite-oxidizing bacteria (NOB) located at the middle and downstream sites (65 and 57 °C, respectively). In addition, the potential in situ metabolic activities of different forms of nitrogen metabolism were estimated through laboratory experiments using bulk microbial mat communities. Finally, the compositional and isotopic variation in nitrogen compounds was investigated in the stream water flowing over the microbial mats and in the interstitial water inside the mats. Although the stream water was characterized by a gradual decrease in the total ammonia concentration (ΣNH3: the sum of ammonia and ammonium concentrations) and a gradual increase in the total concentration of nitrite and nitrate (NO2- + NO3-), the total inorganic nitrogen concentration (TIN: the sum of ΣNH3, NO2- and NO3- concentrations

  10. Soil microbial toxicity of eight polycyclic aromatic compounds: effects on nitrification, the genetic diversity of bacteria, and the total number of protozoans

    DEFF Research Database (Denmark)

    Sverdrup, Line Emilie; Ekelund, Flemming; Krogh, Paul Henning;

    2002-01-01

    measured by denaturant gradient gel electrophoresis. In general, only weak effects at very high concentrations were found for the protozoans. However, for acridine, protozoan numbers were reduced at lower concentrations than those that affected the nitrification process, that is, with a 5% reduction at 380...... mg/kg. For effects on nitrification, toxicity (NOEC values) expressed as soil pore-water concentrations (log10(micromol/L)) showed a significant inverse relationship with lipophilicity (log octanol-water partition coefficient) of the substances (r2 = 0.69, p = 0.011, n = 8). This finding could...... indicate that the toxicity of substances similar to those tested might be predicted by a quantitative structure-activity relationship with lipophilicity as the predictor variable....

  11. Contour detection based on nonclassical receptive field inhibition

    NARCIS (Netherlands)

    Grigorescu, Cosmin; Petkov, Nicolai; Westenberg, Michel A.

    2003-01-01

    We propose a biologically motivated computational step, called nonclassical receptive field (non-CRF) inhibition, more generally surround inhibition or suppression, to improve contour detection in machine vision. Non-CRF inhibition is exhibited by 80% of the orientation-selective neurons in the prim

  12. The effect of nitrification inhibitors on nitrous oxide emissions from cattle urine depositions to grassland under summer conditions in the UK.

    Science.gov (United States)

    Barneze, A S; Minet, E P; Cerri, C C; Misselbrook, T

    2015-01-01

    Nitrous oxide (N2O) has become the prime ozone depleting atmospheric emission and the third most important anthropogenic greenhouse gas, with a global warming potential approximately 300 times higher than CO2. Nitrification and denitrification are processes responsible for N2O emission from the soil after nitrogen input. The application of a nitrification inhibitor can reduce N2O emissions from these processes. The objective of this study was to assess the effect of two different nitrification inhibitors (dicyandiamide (DCD) and a commercial formulation containing two pyrazole derivatives (PD), 1H-1,2,4-triazole and 3-methylpyrazole) on N2O emissions from cattle urine applications for summer grazing conditions in the UK. Experiments were conducted under controlled conditions in a laboratory incubator and under field conditions on a grassland soil. The N2O emissions showed similar temporal dynamics in both experiments. DCD concentration in the soil showed an exponential degradation during the experiment, with a half-life of the order of only 10d (air temperature c. 15 °C). DCD (10 kg ha(-1)) and PD at the highest application rate (3.76 kg ha(-1)) reduced N2O emissions by 13% and 29% in the incubation experiment and by 33% and 6% in the field experiment, respectively, although these reductions were not statistically significant (P>0.05). Under UK summer grazing conditions, these nitrification inhibitors appear to be less effective at reducing N2O emissions than reported for other conditions elsewhere in the literature, presumably due to the higher soil temperature. PMID:24973531

  13. Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy

    Science.gov (United States)

    Eriksson, P. G.; Svensson, J. M.; Carrer, G. M.

    2003-12-01

    The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. 15N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.

  14. Spatial Variability in Nitrification Rates and Ammonia-Oxidizing Microbial Communities in the Agriculturally Impacted Elkhorn Slough Estuary, California ▿ †

    OpenAIRE

    Scott D Wankel; Mosier, Annika C.; Hansel, Colleen M.; Paytan, Adina; Francis, Christopher A.

    2010-01-01

    Ammonia oxidation—the microbial oxidation of ammonia to nitrite and the first step in nitrification—plays a central role in nitrogen cycling in coastal and estuarine systems. Nevertheless, questions remain regarding the connection between this biogeochemical process and the diversity and abundance of the mediating microbial community. In this study, we measured nutrient fluxes and rates of sediment nitrification in conjunction with the diversity and abundance of ammonia-oxidizing archaea (AOA...

  15. amoA Gene Abundances and Nitrification Potential Rates Suggest that Benthic Ammonia-Oxidizing Bacteria and Not Archaea Dominate N Cycling in the Colne Estuary, United Kingdom

    OpenAIRE

    Li, Jialin; Nedwell, David B.; Beddow, Jessica; Alex J Dumbrell; McKew, Boyd A; Thorpe, Emma L.; Whitby, Corinne

    2014-01-01

    Nitrification, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), is important in global nitrogen cycling. In estuaries where gradients of salinity and ammonia concentrations occur, there may be differential selections for ammonia-oxidizer populations. The aim of this study was to examine the activity, abundance, and diversity of AOA and AOB in surface oxic sediments of a highly nutrified estuary that exhibits gradients of salinity and ammonium. AOB and AOA comm...

  16. Pilot-scale tertiary MBBR nitrification at 1°C: characterization of ammonia removal rate, solids settleability and biofilm characteristics.

    Science.gov (United States)

    Young, Bradley; Delatolla, Robert; Ren, Baisha; Kennedy, Kevin; Laflamme, Edith; Stintzi, Alain

    2016-08-01

    Pilot-scale moving bed biofilm reactor (MBBR) is used to investigate the kinetics and biofilm response of municipal, tertiary nitrification at 1°C. The research demonstrates that significant rates of tertiary MBBR nitrification are attainable and stable for extended periods of operation at 1°C, with a maximum removal rate of 230 gN/m(3) d at 1°C. At conventional nitrogen loading rates, low ammonia effluent concentrations below 5 mg-N/L were achieved at 1°C. The biofilm thickness and dry weight biofilm mass (massdw) were shown to be stable, with thickness values showing a correlation to the protein/polysaccharide ratio of the biofilm extracellular polymeric substances. Lastly, tertiary MBBR nitrification is shown to increase the effluent suspended solids concentrations by approximately 3 mg total suspended solids /L, with 19-60% of effluent solids being removed after 30 min of settling. The settleability of the effluent solids was shown to be correlated to the nitrogen loading of the MBBR system. PMID:26789700

  17. Nitrification activity and community structure of nitrite-oxidizing bacteria in the bioreactors operated with addition of pharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Kraigher, Barbara, E-mail: barbara.kraigher@bf.uni-lj.si [University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Chair of Microbiology, Vecna pot 111, 1000 Ljubljana (Slovenia); Mandic-Mulec, Ines [University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Chair of Microbiology, Vecna pot 111, 1000 Ljubljana (Slovenia)

    2011-04-15

    Pharmaceuticals represent a group of the new emerging contaminants, which might influence microbial communities in the activated sludge. Nitrification activity and Nitrospira community structure in the small-scale reactors supplied with different concentrations (0, 50, 200, 500 {mu}g L{sup -1}) of the selected pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid) were evaluated. Ammonia removal was not influenced by selected pharmaceuticals. However, in the two reactors operated with 50 {mu}g L{sup -1} of pharmaceuticals (R50 and R50P), the effluent concentration of N-(NO{sub 2}{sup -} + NO{sub 3}{sup -}) was significantly higher than in the other reactors. Nitrospira community structure was assessed by terminal restriction fragment length polymorphism (T-RFLP) and by cloning and sequencing of the partial genes for 16S rRNA. Nitrospira spp. were detected in all reactors. The two dominant T-RFs represented the sublineages I and II of the genus Nitrospira. Main shifts were observed in the reactors R50 and R50P, where the T-RF representing sublineage II was much higher as compared to the other reactors. Consistent with this, the Nitrospira sublineage II was detected only in the clone libraries from the reactors R50 and R50P. Our results suggest that the relative abundance of Nitrospira sublineage II could be related to the effluent N-(NO{sub 2}{sup -} + NO{sub 3}{sup -}) concentration.

  18. A Microbial Model of Nitrous Oxide Production That Differentiates Nitrification and Denitrification Production Across Spatial and Temporal Scales.

    Science.gov (United States)

    Bouskill, N.; Riley, W. J.; Cheng, Y.; Tang, J.

    2014-12-01

    N2O fluxes from soil to the atmosphere are mainly attributable to the activity of two microbial functional guilds: aerobic autotrophic nitrifiers and anaerobic heterotrophic denitrifying bacteria. The controls on N2O production from these guilds are generally known and include species interactions and a range of environmental factors (e.g., oxygen concentrations, organic matter stoichiometry, substrate availability, mineralization rates). Here we attempt to parse out the conditions controlling N2O production using a trait-based microbial model that predicts N2O production by representing the physiology and ecology of nitrifiers and denitrifiers, and the N2O consumption pathways of heterotrophic bacteria. Following successful application of the standalone microbial model to predict nitrification and denitrification rates and associated N2O fluxes, we ran the model with output from the Community Land Model (CLM4.5) to examine N2O production across spatial and temporal scales, during rainfall events and under global change scenarios (e.g., increased temperature and nitrogen deposition). We discuss our output with respect to what is understood about the complexity of belowground ecosystems and how our approach can help constrain the global N2O budget.

  19. Partial nitrification in an air-lift reactor with long-term feeding of increasing ammonium concentrations.

    Science.gov (United States)

    Chai, Li-Yuan; Ali, Mohammad; Min, Xiao-Bo; Song, Yu-Xia; Tang, Chong-Jian; Wang, Hai-Ying; Yu, Cheng; Yang, Zhi-Hui

    2015-06-01

    The partial nitrification (PN) performance under high ammonium concentrations was evaluated in an airlift reactor (ALR). The ALR was operated for 253days with stepwise elevation of ammonium concentration to 1400mg/L corresponding nitrogen loading rate of 2.1kg/m(3)/d. The ammonium removal rate was finally developed to 2.0kg/m(3)/d with average removal efficiency above 91% and nitrite accumulation percentage of 80%. Results showed that the combined effect of limited DO, high bicarbonate, pH and free ammonia (FA) contributed to the stable nitrite accumulation substantially. The biomass in the ALR was improved with the inception of granulation. Precipitates on biomass surface was unexpectedly experienced which might improve the settleability of PN biomass. Organic functional groups attached to the PN biomass suggested the possible absorbability to different types of pollutant. The results provided important evidence for the possibility of applying an ALR to treat high strength ammonium wastewater. PMID:25768415

  20. Pyruvic Oxime Nitrification and Copper and Nickel Resistance by a Cupriavidus pauculus, an Active Heterotrophic Nitrifier-Denitrifier

    Directory of Open Access Journals (Sweden)

    Miguel Ramirez

    2014-01-01

    Full Text Available Heterotrophic nitrifiers synthesize nitrogenous gasses when nitrifying ammonium ion. A Cupriavidus pauculus, previously thought an Alcaligenes sp. and noted as an active heterotrophic nitrifier-denitrifier, was examined for its ability to produce nitrogen gas (N2 and nitrous oxide (N2O while heterotrophically nitrifying the organic substrate pyruvic oxime [CH3–C(NOH–COOH]. Neither N2 nor N2O were produced. Nucleotide and phylogenetic analyses indicated that the organism is a member of a genus (Cupriavidus known for its resistance to metals and its metabolism of xenobiotics. The microbe (a Cupriavidus pauculus designated as C. pauculus strain UM1 was examined for its ability to perform heterotrophic nitrification in the presence of Cu2+ and Ni2+ and to metabolize the xenobiotic phenol. The bacterium heterotrophically nitrified well when either 1 mM Cu2+ or 0.5 mM Ni2+ was present in either enriched or minimal medium. The organism also used phenol as a sole carbon source in either the presence or absence of 1 mM Cu2+ or 0.5 mM Ni2+. The ability of this isolate to perform a number of different metabolisms, its noteworthy resistance to copper and nickel, and its potential use as a bioremediation agent are discussed.

  1. Operational strategy for nitrogen removal from centrate in a two-stage partial nitrification--anammox process.

    Science.gov (United States)

    Kosari, S F; Rezania, B; Lo, K V; Mavinic, D S

    2014-01-01

    This paper presents the operational strategy for nitrogen removal in a two-stage, partial nitrification (PN) process coupled with anaerobic ammonium oxidation (Anammox) process. The process was used to remove ammonium from centrate obtained from a full-scale, wastewater treatment plant in British Columbia, Canada. The PN, which was carried out in a sequencing batch reactor (SBR), successfully converted approximately 49.5 +/- 1.0% of ammonium to nitrite. The operation of SBR under higher dissolved oxygen in combination with slow feeding resulted in significant reduced HRT without nitrate accumulation. Partially nitrified centrate was further treated in Anammox reactors, where the mixture of ammonium and nitrite was converted mainly to nitrogen gas. Anammox treatment was carried out in two different types of Anammox reactors: a moving bed hybrid reactor and an up-flow fixed-bed biofilm reactor. The hybrid Anammox reactor removed an average of 55.8% of NH4-N, versus the 48.3% NH4-N removed in the up-flow fixed-bed reactor. Nitrite removal in the hybrid and up-flow fixed-bed Anammox reactors averaged 80.8% and 62.5%, respectively. This study also illustrated that in both Anammox reactors, better ammonium removal was achieved when the nitrite to ammonium ratio is between 1.35 and 1.45. As such, alkalinity was found to neither control nor limit the Anammox reaction. PMID:24701906

  2. A new developed airlift reactor integrated settling process and its application for simultaneous nitrification and denitrification nitrogen removal.

    Science.gov (United States)

    Zhang, Tao; Wei, Chaohai

    2013-01-01

    This study presented the performance of simultaneous nitrification and denitrification (SND) process using a new developed hybrid airlift reactor which integrated the activated sludge reaction process in the airlift reactor and the sludge settling separation process in the clarifier. The proposed reactor was started up successfully after 76 days within which the COD and total nitrogen removal rate can reach over 90% and 76.3%, respectively. The effects of different COD/N and DO concentrations on the performance of reactor were investigated. It was found that the influent COD/N maintained at 10 was sufficient for SND and the optimum DO concentration for SND was in the range of 0.5 to 0.8 mg L(-1). Batch test demonstrated that both macroscopic environment caused by the spatial DO concentration difference and microscopic environment caused by the stratification of activated sludge may be responsible for the SND process in the reactor. The hybrid airlift reactor can accomplish SND process in a single reactor and in situ automatic separation of sludge; therefore, it may serve as a promising reactor in COD and nitrogen removal fields. PMID:23935415

  3. Effects of hydraulic retention time on nitrification activities and population dynamics of a conventional activated sludge system

    Institute of Scientific and Technical Information of China (English)

    Hongyan LI; Yu ZHANG; Min YANG; Yoichi KAMAGATA

    2013-01-01

    The effects of hydraulic retention time (HRT) on the nitrification activities and population dynamics of a conventional activated sludge system fed with synthetic inorganic wastewater were investigated over a period of 260 days. When the HRT was gradually decreased from 30 to 5 h, the specific ammonium-oxidizing rates (SAOR) varied between 0.32 and 0.45kg NH4+-N (kg mixed liquor suspended solids (MLSS)·d)-1, and the specific nitrate-forming rates (SNFR) increased from 0.11 to 0.50kg NO3-N (kg MLSS·d)1l, showing that the decrease in HRT led to a significant increase in the nitrite oxidation activity. According to fluorescence in situ hybridization (FISH) analysis results, the proportion of ammonia-oxidizing bacteria (AOBs) among the total bacteria decreased from 33% to 15% with the decrease in HRT, whereas the fraction of nitrite-oxidizing bacteria (NOBs), particularly the fast-growing Nitrobacter sp., increased significantly (from 4% to 15% for NOBs and from 1.5% to 10.6% for Nitrobacter sp.) with the decrease in HRT, which was in accordance with the changes in SNFR. A short HRT favored the relative growth of NOBs, particularly the fast-growing Nitrobacter sp., in the conventional activated sludge system.

  4. Depth investigation of rapid sand filters for drinking water production reveals strong stratification in nitrification biokinetic behavior.

    Science.gov (United States)

    Tatari, K; Smets, B F; Albrechtsen, H-J

    2016-09-15

    The biokinetic behavior of NH4(+) removal was investigated at different depths of a rapid sand filter treating groundwater for drinking water preparation. Filter materials from the top, middle and bottom layers of a full-scale filter were exposed to various controlled NH4(+) loadings in a continuous-flow lab-scale assay. NH4(+) removal capacity, estimated from short term loading up-shifts, was at least 10 times higher in the top than in the middle and bottom filter layers, consistent with the stratification of Ammonium Oxidizing Bacteria (AOB). AOB density increased consistently with the NH4(+) removal rate, indicating their primarily role in nitrification under the imposed experimental conditions. The maximum AOB cell specific NH4(+) removal rate observed at the bottom was at least 3 times lower compared to the top and middle layers. Additionally, a significant up-shift capacity (4.6 and 3.5 times) was displayed from the top and middle layers, but not from the bottom layer at increased loading conditions. Hence, AOB with different physiological responses were active at the different depths. The biokinetic analysis predicted that despite the low NH4(+) removal capacity at the bottom layer, the entire filter is able to cope with a 4-fold instantaneous loading increase without compromising the effluent NH4(+). Ultimately, this filter up-shift capacity was limited by the density of AOB and their biokinetic behavior, both of which were strongly stratified. PMID:27295615

  5. Nitrification activity and community structure of nitrite-oxidizing bacteria in the bioreactors operated with addition of pharmaceuticals

    International Nuclear Information System (INIS)

    Pharmaceuticals represent a group of the new emerging contaminants, which might influence microbial communities in the activated sludge. Nitrification activity and Nitrospira community structure in the small-scale reactors supplied with different concentrations (0, 50, 200, 500 μg L-1) of the selected pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid) were evaluated. Ammonia removal was not influenced by selected pharmaceuticals. However, in the two reactors operated with 50 μg L-1 of pharmaceuticals (R50 and R50P), the effluent concentration of N-(NO2- + NO3-) was significantly higher than in the other reactors. Nitrospira community structure was assessed by terminal restriction fragment length polymorphism (T-RFLP) and by cloning and sequencing of the partial genes for 16S rRNA. Nitrospira spp. were detected in all reactors. The two dominant T-RFs represented the sublineages I and II of the genus Nitrospira. Main shifts were observed in the reactors R50 and R50P, where the T-RF representing sublineage II was much higher as compared to the other reactors. Consistent with this, the Nitrospira sublineage II was detected only in the clone libraries from the reactors R50 and R50P. Our results suggest that the relative abundance of Nitrospira sublineage II could be related to the effluent N-(NO2- + NO3-) concentration.

  6. High-rate partial nitrification treatment of reject water as a pretreatment for anaerobic ammonium oxidation (anammox).

    Science.gov (United States)

    Zhang, Li; Yang, Jiachun; Hira, Daisuke; Fujii, Takao; Furukawa, Kenji

    2011-02-01

    In this study, a lab-scale swim-bed partial nitrification reactor was developed to treat ammonium-rich reject water to achieve an appropriate NO(2)(-)-N/NH(4)(+)-N mixture that could serve as a pretreatment for anaerobic ammonium oxidation (anammox). Strictly controlling the DO concentration was adopted as the main operational strategy. In addition, the influent concentrations of inorganic carbon/ammonium (IC/NH(4)(+)) and alkalinity/ammonium (Alk/NH(4)(+)) that were approximately 0.8 and 4.8, respectively, were regarded as the suitable ratios for the steady and high-rate operation of the reactor in this study. When reject water that was not diluted was introduced to this system, the maximum nitrogen loading rate was 5.9 kg-N/m(3)/day, the ammonium conversion rate was 3.1 kg-N/m(3)/day, and the effluent NO(2)-N/(NO(2)-N+NO(3)-N) percentage ratio was over 99.9%. Furthermore, DNA analysis confirmed the existence of AOB, which was responsible for the stable performance that was achieved in the PN reactor. PMID:21190840

  7. Simultaneous heterotrophic nitrification and aerobic denitrification at high initial phenol concentration by isolated bacterium Diaphorobacter sp. PD-7

    Institute of Scientific and Technical Information of China (English)

    Qilong Ge; Xiuping Yue; Guoying Wang

    2015-01-01

    A strain capable of phenol degradation, heterotrophic nitrification and aerobic denitrification was isolated from activated sludge of coking-plant wastewater ponds under aerobic condition. Based on its morphology, physiology, biochemical analysis and phylogenetic characteristics, the isolate was identified as Diaphorobacter sp. PD-7. Biodegradation tests of phenol showed that the maximum phenol degradation occurred at the late phase of exponential growth stages, with 1400 mg·L-1 phenol completely degraded within 85 h. Diaphorobacter sp. PD-7 accumulated a vast quantity of phenol hydroxylase in this physiological phase, ensuring that the cel s quickly utilize phenol as a sole carbon and energy source. The kinetic behavior of Diaphorobacter sp. PD-7 in batch cultures was investigated over a wide range of initial phenol concentrations (0–1400 mg·L-1) by using the Haldane model, which adequately describes the dynamic behavior of phenol biodegradation by strain Diaphorobacter sp. PD-7. At initial phenol concentration of 1400 mg·L-1, batch experiments (0.25 L flask) of nitrogen removal under aerobic condition gave almost entirely removal of 120.69 mg·L-1 ammonium nitrogen within 75 h, while nitrate nitrogen removal reached 91%within 65 h. Moreover, hydroxylamine oxidase, periplasmic nitrate reductase and nitrite reductase were successful y expressed in the isolate.

  8. Solid respirometry to characterize nitrification kinetics: a better insight for modelling nitrogen conversion in vertical flow constructed wetlands.

    Science.gov (United States)

    Morvannou, Ania; Choubert, Jean-Marc; Vanclooster, Marnik; Molle, Pascal

    2011-10-15

    We developed an original method to measure nitrification rates at different depths of a vertical flow constructed wetland (VFCW) with variable contents of organic matter (sludge, colonized gravel). The method was adapted for organic matter sampled in constructed wetland (sludge, colonized gravel) operated under partially saturated conditions and is based on respirometric principles. Measurements were performed on a reactor, containing a mixture of organic matter (sludge, colonized gravel) mixed with a bulking agent (wood), on which an ammonium-containing liquid was applied. The oxygen demand was determined from analysing oxygen concentration of the gas passing through the reactor with an on-line analyzer equipped with a paramagnetic detector. Within this paper we present the overall methodology, the factors influencing the measurement (sample volume, nature and concentration of the applied liquid, number of successive applications), and the robustness of the method. The combination of this new method with a mass balance approach also allowed determining the concentration and maximum growth rate of the autotrophic biomass in different layers of a VFCW. These latter parameters are essential inputs for the VFCW plant modelling. PMID:21831403

  9. Biology Notes.

    Science.gov (United States)

    School Science Review, 1982

    1982-01-01

    Presents procedures, exercises, demonstrations, and information on a variety of biology topics including labeling systems, biological indicators of stream pollution, growth of lichens, reproductive capacity of bulbous buttercups, a straw balance to measure transpiration, interaction of fungi, osmosis, and nitrogen fixation and crop production. (DC)

  10. Partial nitrification in MBBRs for mainstream deammonification with thin biofilms and alternating feed supply.

    Science.gov (United States)

    Piculell, M; Christensson, M; Jönsson, K; Welander, T

    2016-01-01

    A new principle for mainstream nitrogen removal through nitritation followed by anammox was studied in a two-stage moving bed biofilm reactor (MBBR) configuration. The first stage was optimized for nitritation by using thin biofilms and a feed alternating between synthetic mainstream wastewater at 15°C and, for shorter periods, synthetic reject water at 30 °C. The exposure of the biofilm to reject water conditions aimed to improve the growth conditions for ammonia oxidizing bacteria, while inhibiting nitrite oxidizing bacteria. The biofilm thickness was maintained below 200 μm to ensure high exposure of the total biomass to the bulk reactor conditions. Nitritation was successfully achieved in the configuration, with a nitrite accumulation ratio above 75% during the majority of the study, and ammonia removal rates between 0.25 and 0.50 g NH4-N/L,d. The anoxic second stage, optimized for anammox, was fed with the effluent from the nitritation reactor, reaching nitrogen removal rates above 0.20 g TN/L,d. PMID:27003064

  11. Quantum Biology

    Directory of Open Access Journals (Sweden)

    Alessandro Sergi

    2009-06-01

    Full Text Available A critical assessment of the recent developmentsof molecular biology is presented.The thesis that they do not lead to a conceptualunderstanding of life and biological systems is defended.Maturana and Varela's concept of autopoiesis is briefly sketchedand its logical circularity avoided by postulatingthe existence of underlying living processes,entailing amplification from the microscopic to the macroscopic scale,with increasing complexity in the passage from one scale to the other.Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces,is criticized. It is suggested that the correct interpretationof quantum dispersion forces (van der Waals, hydrogen bonding, and so onas quantum coherence effects hints at the necessity of includinglong-ranged forces (or mechanisms for them incondensed matter theories of biological processes.Some quantum effects in biology are reviewedand quantum mechanics is acknowledged as conceptually important to biology since withoutit most (if not all of the biological structuresand signalling processes would not even exist. Moreover, it is suggested that long-rangequantum coherent dynamics, including electron polarization,may be invoked to explain signal amplificationprocess in biological systems in general.

  12. Quantum Biology

    CERN Document Server

    Sergi, Alessandro

    2009-01-01

    A critical assessment of the recent developments of molecular biology is presented. The thesis that they do not lead to a conceptual understanding of life and biological systems is defended. Maturana and Varela's concept of autopoiesis is briefly sketched and its logical circularity avoided by postulating the existence of underlying {\\it living processes}, entailing amplification from the microscopic to the macroscopic scale, with increasing complexity in the passage from one scale to the other. Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces, is criticized. It is suggested that the correct interpretation of quantum dispersion forces (van der Waals, hydrogen bonding, and so on) as quantum coherence effects hints at the necessity of including long-ranged forces (or mechanisms for them) in condensed matter theories of biological processes. Some quantum effects in biology are reviewed and quantum mechanics is acknowledge...

  13. Can nitrification bring us to Mars? The role of microbial interactions on nitrogen recovery in life support systems

    Science.gov (United States)

    Christiaens, Marlies E. R.; Lasseur, Christophe; Clauwaert, Peter; Boon, Nico; Ilgrande, Chiara; Vlaeminck, Siegfried

    2016-07-01

    Human habitation in space requires artificial environment recirculating fundamental elements to enable the highest degree of autonomy . The European Space Agency, supported by a large consortoium of European organisationsdevelop the Micro-Ecological Life Support System (MELiSSA) to transform the mission wastes waste (a.o. organic fibers, CO2, and urine) into water, oxygen, and food (Lasseur et al., 2010). Among these wastes, astronauts' urine has a high potential to provide nitrogen as a fertilizer for food production. As higher plant growth in space is typically proposed to be performed in hydroponics, liquid fertilizer containing nitrates is preferred. An Additional Unit for Water Treatment is developed for urine nitrification by means of a synthetic microbial community. The key players in this consortium are ureolytic bacteria to hydrolyse the main nitrogen source in urine, urea, to ammonium and carbon dioxide as well as oxidation of organic compounds present in urine, ammonium oxidizing bacteria (AOB) to convert ammonium to nitrite (nitritation), and the nitrate oxidizing bacteria (NOB) to produce nitrate (nitratation). Pure AOB strains Nitrosomonas ureae Nm10 and Nitrosomonas europaea ATCC 19718, pure NOB strains Nitrobacter winogradskyi Nb-255 and Nitrobacter vulgaris Z, and interactions within synthetic consortia of one AOB and one NOB or all together were tested. As the initial salinity of fresh urine can be as high as 30 mS/cm, the functionality of selected pure strains and synthetic consortia was evaluated by means of the nitritation and nitratation activity at varying NaCl salinities (5, 10, and 30 mS/cm). The nitritation activity of pure AOB strains was compared with the synthetic consortia. Both N. ureae and Ns. europaea benefit from the presence of Nb. winogradskyi as the ammonium oxidation rates of 1.7 ± 0.7 and 6.4 ± 0.6 mg N/L.d at 5 mS/cm, respectively, doubled. These results are in line with the findings of Perez et al (2015) observing a lower

  14. Characteristics of extracellular polymeric substances from sludge and biofilm in a simultaneous nitrification and denitrification system under high salinity stress.

    Science.gov (United States)

    Zhao, Linting; She, Zonglian; Jin, Chunji; Yang, Shiying; Guo, Liang; Zhao, Yangguo; Gao, Mengchun

    2016-09-01

    The composition and distribution of extracellular polymeric substance (EPS) both from suspended sludge and attached biofilm were investigated in a simultaneous nitrification and denitrification (SND) system with the increase of the salinity from 1.0 to 3.0 %. Fourier-transform infrared (FTIR) spectroscopy and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy were used to examine proteins (PN), polysaccharides (PS) and humic substances (HS) present in EPS. High total nitrogen removal (above 83.9 %) via SND was obtained in the salinity range of 1.0-2.5 %. Total EPS in the sludge increased from 150.2 to 200.6 mg/gVSS with the increase of salinity from 1.0 to 3.0 %, whereas the corresponding values in the biofilm achieved the maximum of 288.6 mg/g VSS at 2.0 % salinity. Dominant composition of EPS was detected as HS in both sludge and biofilm, having the percentages of 50.6-68.6 and 41.1-69.9 % in total EPS, respectively. Both PN and PS contents in soluble EPS (S-EPS), loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) of sludge and biofilm increased with the increased salinity. The FTIR spectrum and 3D-EEM fluorescence spectroscopy of S-EPS, LB-EPS and TB-EPS in the sludge and biofilm showed the changes of functional groups and conformations of the compositions in EPS with the increase of salinity. The results demonstrated that the characteristics of EPS varied from sludge to biofilm. The obtained results could provide a better understanding of the salinity effect on the EPS characteristics in a SND system. PMID:27126502

  15. Advanced phosphorus recovery using a novel SBR system with granular sludge in simultaneous nitrification, denitrification and phosphorus removal process.

    Science.gov (United States)

    Lu, Yong-Ze; Wang, Hou-Feng; Kotsopoulos, Thomas A; Zeng, Raymond J

    2016-05-01

    In this study, a novel process for phosphorus (P) recovery without excess sludge production from granular sludge in simultaneous nitrification-denitrification and P removal (SNDPR) system is presented. Aerobic microbial granules were successfully cultivated in an alternating aerobic-anaerobic sequencing batch reactor (SBR) for removing P and nitrogen (N). Dense and stable granular sludge was created, and the SBR system showed good performance in terms of P and N removal. The removal efficiency was approximately 65.22 % for N, and P was completely removed under stable operating conditions. Afterward, new operating conditions were applied in order to enhance P recovering without excess sludge production. The initial SBR system was equipped with a batch reactor and a non-woven cloth filter, and 1.37 g of CH3COONa·3H2O was added to the batch reactor after mixing it with 1 L of sludge derived from the SBR reactor to enhance P release in the liquid fraction, this comprises the new system configuration. Under the new operating conditions, 93.19 % of the P contained in wastewater was released in the liquid fraction as concentrated orthophosphate from part of granular sludge. This amount of P could be efficiently recovered in the form of struvite. Meanwhile, a deterioration of the denitrification efficiency was observed and the granules were disintegrated into smaller particles. The biomass concentration in the system increased firstly and then maintained at 4.0 ± 0.15 gVSS/L afterward. These results indicate that this P recovery operating (PRO) mode is a promising method to recover P in a SNDPR system with granular sludge. In addition, new insights into the granule transformation when confronted with high chemical oxygen demand (COD) load were provided. PMID:26728017

  16. Biological Water Processor and Forward Osmosis Secondary Treatment

    Science.gov (United States)

    Shull, Sarah; Meyer, Caitlin

    2014-01-01

    The goal of the Biological Water Processor (BWP) is to remove 90% organic carbon and 75% ammonium from an exploration-based wastewater stream for four crew members. The innovative design saves on space, power and consumables as compared to the ISS Urine Processor Assembly (UPA) by utilizing microbes in a biofilm. The attached-growth system utilizes simultaneous nitrification and denitrification to mineralize organic carbon and ammonium to carbon dioxide and nitrogen gas, which can be scrubbed in a cabin air revitalization system. The BWP uses a four-crew wastewater comprised of urine and humidity condensate, as on the ISS, but also includes hygiene (shower, shave, hand washing and oral hygiene) and laundry. The BWP team donates 58L per day of this wastewater processed in Building 7.

  17. Cellulase Inhibition by High Concentrations of Monosaccharides

    DEFF Research Database (Denmark)

    Hsieh, Chia-Wen; Cannella, David; Jørgensen, Henning;

    2014-01-01

    Biological degradation of biomass on an industrial scale culminates in high concentrations of end products. It is known that the accumulation of glucose and cellobiose, end products of hydrolysis, inhibit cellulases and decrease glucose yields. Aside from these end products, however, other...... that low free water availability contributes to cellulase inhibition. Of the hydrolytic enzymes involved, those acting on the cellulose substrate, that is, exo- and endoglucanases, were the most inhibited. The β -glucosidases were shown to be less sensitive to high monosaccharide concentrations except...

  18. Biological Oceanography

    Science.gov (United States)

    Abbott, M. R.

    1984-01-01

    Within the framework of global biogeochemical cycles and ocean productivity, there are two areas that will be of particular interest to biological oceanography in the 1990s. The first is the mapping in space time of the biomass and productivity of phytoplankton in the world ocean. The second area is the coupling of biological and physical processes as it affects the distribution and growth rate of phytoplankton biomass. Certainly other areas will be of interest to biological oceanographers, but these two areas are amenable to observations from satellites. Temporal and spatial variability is a regular feature of marine ecosystems. The temporal and spatial variability of phytoplankton biomass and productivity which is ubiquitous at all time and space scales in the ocean must be characterized. Remote sensing from satellites addresses these problems with global observations of mesocale (2 to 20 days, 10 to 200 km) features over a long period of time.

  19. Biological preconcentrator

    Science.gov (United States)

    Manginell, Ronald P.; Bunker, Bruce C.; Huber, Dale L.

    2008-09-09

    A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

  20. Role of nitrification inhibitor DMPP( 3,4-dimethylpyrazole phosphate) in NO3--N accumulation in greengrocery( Brassica campestris L. Ssp. Chinensis )and vegetable soil

    Institute of Scientific and Technical Information of China (English)

    XU Chao; WU Liang-huan; JU Xiao-tang; ZHANG Fu-suo

    2005-01-01

    The influence of nitrification inhibitor(NI) 3,4-dimethylpyrazole phosphate (DMPP) on nitrate accumulation in greengrocery( Brassica campestris L. ssp. chinensis) and vegetable soil at surface layer were investigated in field experiments in 2002 and 2003.Results showed that NI DMPP took no significant effect on yields of edible parts of greengrocery, but it could significantly decrease NO3- -N concentration in greengrccery and in vegetable soil at surface layer. In addition, NI DMPP could reduce the NO3--N concentration during the prophase stage of storage.