The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of ...The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as chemical oxygen demand, NO2^-, NO3^-, NH4^＋, pH, and N2O. indicated by rhythmic changes of total N, dissolved oxygen, Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%-16.1% and 0-0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.展开更多
The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. When influent Ammonia nitrogen concentration was 42. 78 - 73. 62 mg/L. The average amm...The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. When influent Ammonia nitrogen concentration was 42. 78 - 73. 62 mg/L. The average ammonia nitrogen removal rate was 81.32% from the bioceramics reactor. Sodium acetate and ammonium chloride were used as carbon and nitrogen source. The COD removal rates by microorganisms of strain wgy21 and wgy36 were 56.1% and 45.45%, respectively. The TN removal rates by microorganisms of strain wgy21 and wgy36 were 65.85% and 67. 98%, respectively. At the same time, the concentration of ammonium nitrogen was with the removal rates of 75.25% and 84.96%, and it also had the function of producing NO2 - N. Sodium acetate and sodium nitrite were used as carbon and nitrogen source. Through the 12 days of the aerobic culture, the COD femoral rates by microorganisms of strain wgy21 and wgy36 were 29.25% and 22.08%, respectively. NO2 -N concentration decreased slowly. Comparison, similarity of wgy21 and many Acinetobacter sp. ≥99%, similarity of wgy36 and many Acinetobacter sp. ≥99%. Refer to routine physiologicalbiochemical characteristic determination, further evidences showed that wgy21 and wgy36 belong to Acinetobacter sp., respectively.展开更多
Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature were conducted and results showed that seawater salinity had a strong negative effect on notrouomonas and nitrobaeter growth, bu...Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature were conducted and results showed that seawater salinity had a strong negative effect on notrouomonas and nitrobaeter growth, but much more on the nitrobaeter. The nitrification action was mainly accomplished by nitrosomonas. Bench-scale experiments using two SBRs were carried out for further investigation under different conditions of salinities, ammonia loadings and temperatures. Biological nitrogen removal via nitrite pathway from wastewater containing 30 percent seawater was achieved, but the ammonia removal efficiency was strongly related not only to the influent ammonia loading at different salinities but also to temperatures. When the ratio of seawater to wastewater was 30 percent, and the ammonia loading was below the critical value of 0. 15 kgNH4 ^＋ -N/（ kgMLSS · d） , the ammonia removal efficiency via nitrite pathway was above 90 %. The critical level of ammonia loading was 0. 15, 0. 08 and 0. 03 kgNH4 ^＋ -N/（ kgMLSS · d） respectively at different temperatures of 30℃, 25℃ and 20℃ when the influent ammonia concentration was 60 - 80 mg/L and pH was 7.5 - 8.0.展开更多
This paper investigates the effect of using sodium citrate（NaC6H5O6·2H2O）as sole carbon source for nitrate removal from drinking water.With sodium citrate as sole carbon source, batch experiments have been cond...This paper investigates the effect of using sodium citrate（NaC6H5O6·2H2O）as sole carbon source for nitrate removal from drinking water.With sodium citrate as sole carbon source, batch experiments have been conducted to study the law of denitrification influenced by pH, C/N and temperature. Results show that a denitrification rate reaching 1.32 g NO-3-N /（g Biomass·d） was obtained when pH was at 7.5,C/N at 1.7（atom ratio）, and temperature from 20 ℃ to 30 ℃. The results also show that denitrification rate with sodium citrate as carbon source approaches to that with methanol as carbon source.展开更多
In a high concentration substrate medium, a heterotrophic bacterium with high removal efficiency of ammonium, named W1, was isolated from activated sludge of coking wastewater treatment facility. The bacterium was Gra...In a high concentration substrate medium, a heterotrophic bacterium with high removal efficiency of ammonium, named W1, was isolated from activated sludge of coking wastewater treatment facility. The bacterium was Gram-negative, rod-shaped, and identified preliminarily as Alcaligenes sp. according to its morphological and physiological properties and its 16S rRNA gene sequence analysis. In the high concentration ammonium medium (400 mg·L 1 4 NH -N), the effects of C source, N source, C/N ratio and initial pH of medium on ammonium removal were investigated in order to determine the optimal condition for strain W1. The maximum ammonium removal was around 95% in 4 days in an improved medium. The production of N 2 gas was examined in a closed system that was full of pure oxygen at the beginning. N 2 gas was detected in the system after 4 days of cultivation, which further testified that strain W1 has heterotrophic nitrification and aerobic denitrification abilities simultaneously.展开更多
Conventional water purified processes have low removal efficiencies for low concentrations of ammonia nitrogen, nitrite nitrogen and micro-pollutants. The efficiency and mechanisms of a novel immobilized biological ac...Conventional water purified processes have low removal efficiencies for low concentrations of ammonia nitrogen, nitrite nitrogen and micro-pollutants. The efficiency and mechanisms of a novel immobilized biological activated carbon (IBAC) process to remove those pollutants from treated potable water was investigated. Operated at a hydraulic retention time of 24 minutes, the IBAC process achieved ammonia nitrogen, nitrite nitrogen and organic micro-pollutants (measured as COD equivalent) removal efficiencies of 95%, 96% and 37%, respectively. A GC/MS analysis of the organic micro-pollutants revealed that the initial 24 organic compounds in the in-coming water were reduced to 7 after the IBAC treatment. The organic micro-pollutant removal efficiency decreased with decreasing in-coming concentrations. Pollutant reduction in the IBAC process was achieved by a rapid physical adsorption on the activated carbon, which effectively retained the pollutants in the system despite the short hydraulic retention time, followed by a slower biological enzymatic degradation of the pollutants.展开更多
This study was conducted to verify and discuss the denitrifying dephosphatation under different levels of nitrate concentration and retention time of anoxic/aerobic process in a Sequencing Batch Reactor (SBR). The res...This study was conducted to verify and discuss the denitrifying dephosphatation under different levels of nitrate concentration and retention time of anoxic/aerobic process in a Sequencing Batch Reactor (SBR). The results of tests demonstrated that there were two kinds of phosphorus-accumulating organisms (PAOs) in the biological excess phosphorus removal (BEPR) system. One was non-DNPAOs that could only use oxygen as terminal electron acceptors, the other was denitrifying PAOs (DNPAOs) that could use both nitrate and oxygen as terminal electron acceptors. Phosphorus uptake efficiency could be attained under anoxic period ranging from 28.7%-96.7% in an anaerobic/anoxic/aerobic system. Experimental results showed that nitrate concentration and retention time of anoxic/aerobic process were the key factors affecting the course of denitrifying dephosphatation.展开更多
O-nitro-phenol wastewater which contains refractory organic matters can not be degraded by conventional biological methods. In this work, o-nitro-phenol wastewater was effectively treated using magnetization-enhanced ...O-nitro-phenol wastewater which contains refractory organic matters can not be degraded by conventional biological methods. In this work, o-nitro-phenol wastewater was effectively treated using magnetization-enhanced oxidation by NaCIO solutions. The pollutant concentrations in wastewater were 250 mg/L o-nitro-phenol, 2,000 mg/L CODcr and 150 times color. The experimental results show that, using the method in this work, 94.4% o-nitro-phenol, 94.2% CODCr and 100% color can be removed at pH 6, 200 mg charcoal, 8 mL oxidizer, 5 min reaction time in 1000 mL wastewater. The treatment can be enhanced under magnetic field. CODCr and o-nitro-phenol removal can keep unchanged while the reaction time can be reduced to 3 min when the intensity of magnetic field was 60 mT.展开更多
Lab scale biological treatment system was constructed from acrylic and operated using synthetic wastewater to evaluate the nitrification performance using different media. The media used for were Ceramic Ring A （CRA...Lab scale biological treatment system was constructed from acrylic and operated using synthetic wastewater to evaluate the nitrification performance using different media. The media used for were Ceramic Ring A （CRA）, Ceramic Ring B （CRB）, Japanese Filter Mat （JFM）, and Filter Wool （FW）. Laboratory studies were conducted, in order to evaluate the nitrification performance of different media types, at different synthetic wastewater flow rates, ranging from 0.03 to 0.045 m3/hr. The results from experiments suggest that at higher water flow rates, there was a decrease in nitrification for all media types. Based on the ammonia and nitrite removal rates, FW media gave the optimum nitrification, of up to 0.46 g/m2/day and 0.09 g/m2/day, respectively. Besides, in this study, the surface texture of the media is the main factor that affected the volumetric ammonia and nitrite conversion rates （VTR and VNR）. JFM gave the greatest VTR and VNR performance, compared with the other media展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 40471072 and 30470060) and the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-413-3-1).
文摘The rate of nitrous oxide emission from a laboratory sequence batch reactor （SBR） wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as chemical oxygen demand, NO2^-, NO3^-, NH4^＋, pH, and N2O. indicated by rhythmic changes of total N, dissolved oxygen, Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%-16.1% and 0-0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.
基金National Natural Science Foundation of China(NO.50521140075)
文摘The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. When influent Ammonia nitrogen concentration was 42. 78 - 73. 62 mg/L. The average ammonia nitrogen removal rate was 81.32% from the bioceramics reactor. Sodium acetate and ammonium chloride were used as carbon and nitrogen source. The COD removal rates by microorganisms of strain wgy21 and wgy36 were 56.1% and 45.45%, respectively. The TN removal rates by microorganisms of strain wgy21 and wgy36 were 65.85% and 67. 98%, respectively. At the same time, the concentration of ammonium nitrogen was with the removal rates of 75.25% and 84.96%, and it also had the function of producing NO2 - N. Sodium acetate and sodium nitrite were used as carbon and nitrogen source. Through the 12 days of the aerobic culture, the COD femoral rates by microorganisms of strain wgy21 and wgy36 were 29.25% and 22.08%, respectively. NO2 -N concentration decreased slowly. Comparison, similarity of wgy21 and many Acinetobacter sp. ≥99%, similarity of wgy36 and many Acinetobacter sp. ≥99%. Refer to routine physiologicalbiochemical characteristic determination, further evidences showed that wgy21 and wgy36 belong to Acinetobacter sp., respectively.
基金Sponsored by the National Natural Science Foundation of China (No. 50138010, 20877086)National 10th 5 Scientific Research Project of Ministry of Science and Technology of China (Grant No.2001BA610A-09)+1 种基金Knowledge Innovation Program of the Chinese Academy of Sciences (RCEES-QN-200706)the Special Funds for Young Scholars of RCEES
文摘Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature were conducted and results showed that seawater salinity had a strong negative effect on notrouomonas and nitrobaeter growth, but much more on the nitrobaeter. The nitrification action was mainly accomplished by nitrosomonas. Bench-scale experiments using two SBRs were carried out for further investigation under different conditions of salinities, ammonia loadings and temperatures. Biological nitrogen removal via nitrite pathway from wastewater containing 30 percent seawater was achieved, but the ammonia removal efficiency was strongly related not only to the influent ammonia loading at different salinities but also to temperatures. When the ratio of seawater to wastewater was 30 percent, and the ammonia loading was below the critical value of 0. 15 kgNH4 ^＋ -N/（ kgMLSS · d） , the ammonia removal efficiency via nitrite pathway was above 90 %. The critical level of ammonia loading was 0. 15, 0. 08 and 0. 03 kgNH4 ^＋ -N/（ kgMLSS · d） respectively at different temperatures of 30℃, 25℃ and 20℃ when the influent ammonia concentration was 60 - 80 mg/L and pH was 7.5 - 8.0.
文摘This paper investigates the effect of using sodium citrate（NaC6H5O6·2H2O）as sole carbon source for nitrate removal from drinking water.With sodium citrate as sole carbon source, batch experiments have been conducted to study the law of denitrification influenced by pH, C/N and temperature. Results show that a denitrification rate reaching 1.32 g NO-3-N /（g Biomass·d） was obtained when pH was at 7.5,C/N at 1.7（atom ratio）, and temperature from 20 ℃ to 30 ℃. The results also show that denitrification rate with sodium citrate as carbon source approaches to that with methanol as carbon source.
基金Supported by the National Natural Science Foundation of China (51078252)the International Cooperation Projects of Shanxi Province (2010081018)the Natural Science Foundation of Shanxi Province (2010011016-1)
文摘In a high concentration substrate medium, a heterotrophic bacterium with high removal efficiency of ammonium, named W1, was isolated from activated sludge of coking wastewater treatment facility. The bacterium was Gram-negative, rod-shaped, and identified preliminarily as Alcaligenes sp. according to its morphological and physiological properties and its 16S rRNA gene sequence analysis. In the high concentration ammonium medium (400 mg·L 1 4 NH -N), the effects of C source, N source, C/N ratio and initial pH of medium on ammonium removal were investigated in order to determine the optimal condition for strain W1. The maximum ammonium removal was around 95% in 4 days in an improved medium. The production of N 2 gas was examined in a closed system that was full of pure oxygen at the beginning. N 2 gas was detected in the system after 4 days of cultivation, which further testified that strain W1 has heterotrophic nitrification and aerobic denitrification abilities simultaneously.
文摘Conventional water purified processes have low removal efficiencies for low concentrations of ammonia nitrogen, nitrite nitrogen and micro-pollutants. The efficiency and mechanisms of a novel immobilized biological activated carbon (IBAC) process to remove those pollutants from treated potable water was investigated. Operated at a hydraulic retention time of 24 minutes, the IBAC process achieved ammonia nitrogen, nitrite nitrogen and organic micro-pollutants (measured as COD equivalent) removal efficiencies of 95%, 96% and 37%, respectively. A GC/MS analysis of the organic micro-pollutants revealed that the initial 24 organic compounds in the in-coming water were reduced to 7 after the IBAC treatment. The organic micro-pollutant removal efficiency decreased with decreasing in-coming concentrations. Pollutant reduction in the IBAC process was achieved by a rapid physical adsorption on the activated carbon, which effectively retained the pollutants in the system despite the short hydraulic retention time, followed by a slower biological enzymatic degradation of the pollutants.
基金Sponsored by the National Natural Science Foundation of China(Grant No50008014)
文摘This study was conducted to verify and discuss the denitrifying dephosphatation under different levels of nitrate concentration and retention time of anoxic/aerobic process in a Sequencing Batch Reactor (SBR). The results of tests demonstrated that there were two kinds of phosphorus-accumulating organisms (PAOs) in the biological excess phosphorus removal (BEPR) system. One was non-DNPAOs that could only use oxygen as terminal electron acceptors, the other was denitrifying PAOs (DNPAOs) that could use both nitrate and oxygen as terminal electron acceptors. Phosphorus uptake efficiency could be attained under anoxic period ranging from 28.7%-96.7% in an anaerobic/anoxic/aerobic system. Experimental results showed that nitrate concentration and retention time of anoxic/aerobic process were the key factors affecting the course of denitrifying dephosphatation.
文摘O-nitro-phenol wastewater which contains refractory organic matters can not be degraded by conventional biological methods. In this work, o-nitro-phenol wastewater was effectively treated using magnetization-enhanced oxidation by NaCIO solutions. The pollutant concentrations in wastewater were 250 mg/L o-nitro-phenol, 2,000 mg/L CODcr and 150 times color. The experimental results show that, using the method in this work, 94.4% o-nitro-phenol, 94.2% CODCr and 100% color can be removed at pH 6, 200 mg charcoal, 8 mL oxidizer, 5 min reaction time in 1000 mL wastewater. The treatment can be enhanced under magnetic field. CODCr and o-nitro-phenol removal can keep unchanged while the reaction time can be reduced to 3 min when the intensity of magnetic field was 60 mT.
文摘Lab scale biological treatment system was constructed from acrylic and operated using synthetic wastewater to evaluate the nitrification performance using different media. The media used for were Ceramic Ring A （CRA）, Ceramic Ring B （CRB）, Japanese Filter Mat （JFM）, and Filter Wool （FW）. Laboratory studies were conducted, in order to evaluate the nitrification performance of different media types, at different synthetic wastewater flow rates, ranging from 0.03 to 0.045 m3/hr. The results from experiments suggest that at higher water flow rates, there was a decrease in nitrification for all media types. Based on the ammonia and nitrite removal rates, FW media gave the optimum nitrification, of up to 0.46 g/m2/day and 0.09 g/m2/day, respectively. Besides, in this study, the surface texture of the media is the main factor that affected the volumetric ammonia and nitrite conversion rates （VTR and VNR）. JFM gave the greatest VTR and VNR performance, compared with the other media
