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...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 denitrification 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 floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.展开更多
Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. S...Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated 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 programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency 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% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.展开更多
The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membra...The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...展开更多
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 ...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.展开更多
The influence of main process parameters on simultaneous nitrification and denitrification （SND） in a sequencing batch reactor （SBR） were investigated while treating actual municipal sewage. The influent average c...The influence of main process parameters on simultaneous nitrification and denitrification （SND） in a sequencing batch reactor （SBR） were investigated while treating actual municipal sewage. The influent average concentration of CODcr and total nitrogen was 350mg-L-l and 35mg.L-l. The experiment indicated the following four operation control strategies： （1） When operation cycle was 6 hours, oxidation of organic pollutants and simultaneous nitrification and denitrification could well completed in the SBR reactor; （2） TN removal rate could be increased significantly, 40% higher than traditional SBR processes when idle period was set between influent and aeration; （3） The time of idle period could affect simultaneous nitrification and denitrification and the best time is 30 minutes; （4） Increase of sludge organic load may improve TN removal efficiency, but NH3-N removal efficiency declines.展开更多
In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was...In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (FeSO4/Fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, Ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.展开更多
For urban wastewater treatment,we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand（COD）,NH4＋-N,and total n...For urban wastewater treatment,we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand（COD）,NH4＋-N,and total nitrogen（TN） removal performance.The removal rates of COD,NH4＋-N and TN were 88.2%,95.7%,and 86.4% with e？uent concentrations of COD,NH4＋-N and TN less than 50,8,and 10 mg/L,respectively.Biomass and bacterial activities were also measured,with results showing more nitrobacteria in the activated sludge than in the biofilm;however,bacterial activity of the biofilm biomass and the activated sludge were similar.Nitrogen concentrations during the process were also detected,with simultaneous nitrification and denitrification found to be obvious.展开更多
An aerobic sequencing batch biofilm reactor(SBBR)packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and deni-trification.The SBBR is advantageous for creating an anoxic c...An aerobic sequencing batch biofilm reactor(SBBR)packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and deni-trification.The SBBR is advantageous for creating an anoxic condition,and the biofilm can absorb and store carbon for good nitrification and denitrification.An average concentra-tion 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 effluent TN concentra-tion increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L.The efficiency of simultaneous nitrification and denitrification(SND)increased with increasing thickness of the biofilm.The influent concen-tration 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.展开更多
Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process...Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional 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 exam-ined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentra-tion is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7%with solids retention time(SRT)of 45 d,C/N value of 10,and F/M ratio of 0.1 g COD/(g MLSS·d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.展开更多
To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was...To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobicanoxic oxidation ditch （OD）, where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification （SND） rate （rSND） was put forward to quantify SND. The results indicate that： （1） high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen （TN） and total phosphate （TP） removal rates were 80% and 85%, respectively; （2） when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; （3） the natural logarithm of the ratio of NOx to NH4^＋ in the effluent had a linear correlation to oxidation-reduction potential （ORP）; （4） when NO3^- was less than 6 mg/L, high phosphorus removal efficiency could be achieved; （5） denitrifying phosphorus removal （DNPR） could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.展开更多
A lab-scale sequencing batch reactor （SBR） was set-up and the aerobic granular sludge was successfully incubated using anaerobic granular sludge as seed sludge. Nitrogen was partially removed by simultaneous nitrifi...A lab-scale sequencing batch reactor （SBR） was set-up and the aerobic granular sludge was successfully incubated using anaerobic granular sludge as seed sludge. Nitrogen was partially removed by simultaneous nitrification and denitrification （SND） via nitrite with free ammonia （FA） of about 10 mg/L. The denaturing gradient gel electrophoresis （DGGE） method was used to investigate community structure of α-Proteobacteria, β-Proteobacteria, ammonia oxidizing bacteria （AOB）, and Nitrospira populations during start-up. The population sizes of bacteria, AOB and Nitrospira were examined using real-time PCR method. The analysis of community structure and Shannon index showed that stable structure of AOB population was obtained at day 35, while the communities of α- Proteobacteria, β-Proteobacteria, and Nitrospira became stable after day 45. At stable stage, the average cell densities were 1.1× 10^12, 2.2×10^10 and 1.0×10^10 cells/L for bacteria, AOB and Nitrospira, respectively. The relationship between characteristics of nitrifying bacteria community and nitrogenous substrate utilization constant was discussed by calculating Pearson correlation. Certain correlation seemed to exist between population size, biodiversity, and degradation constant. And the influence of population size might be greater than that of biodiversity.展开更多
The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled co...The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled conditions to proliferate the nitrifiers. Heterotrophic nitrifying bacteria were isolated from the system in which the efficiency of total nitrogen(TN) removal was up to 80%. Since no autotrophic ammonium and nitrite oxidizers could be detected by fluorescence in situ hybridization(FISH), oxidized-N production was unlikely to be catalyzed by autotrophic nitrifiers during the heterotrophic nitrifiers' isolation in this study. The batch test results indicate that the isolated heterotrophic bacteria were able to nitrify. After 3 weeks incubation, the efficiencies of the COD removal by the three isolated bacterial strains B1, B2, and B3 were 52 6%, 71 7%, and 77 7%, respectively. The efficiencies of the TN removal by B1, B2, and B3 were 35 6%, 61 2% and 68 7%, respectively.展开更多
To enhance the nitrogen removal,a systemic monitoring of the biological and hydrological parameters of Carrousel oxidation ditch in Chongqing Jingkou Wastewater Treatment Plant was carried out to study the feasibility...To enhance the nitrogen removal,a systemic monitoring of the biological and hydrological parameters of Carrousel oxidation ditch in Chongqing Jingkou Wastewater Treatment Plant was carried out to study the feasibility of simultaneous nitrification and denitrification(SND).The variation and distribution of parameters such as flow velocity,concentration of dissolved oxygen(DO) and mixed liquor suspended solids(MLSS) in oxidation ditch were monitored and analyzed,which were major control factors for SND.The results showed that,the dimensional distribution of flow velocity,DO and MLSS were affected significantly by the operation condition of the aeration wheels.With all the four aeration wheels being in operation,DO and flow velocity were higher and the mixing of MLSS was sufficient.With three aeration wheels being in operation,the flow velocity in most of the bottom areas was enough to meet the basic requirements of no deposition,and the anaerobic region and aerobic region could exist simultaneously in one oxidation ditch,which was helpful to the process of SND.According to spatial distribution characteristics of the flow velocity,DO and soluble components under optimized condition,different functional zones of biochemical reaction in the Carrousel oxidation ditch system were defined,which might contribute to the optimization control and SND of Carrousel oxidation ditch.展开更多
Performance of a full-scale anoxic-oxic activated sludge treatment plant（4.0×10-5 m-3/day for the first-stage project） was followed during a year.The plant performed well for the removal of carbon,nitrogen and ...Performance of a full-scale anoxic-oxic activated sludge treatment plant（4.0×10-5 m-3/day for the first-stage project） was followed during a year.The plant performed well for the removal of carbon,nitrogen and phosphorus in the process of treating domestic wastewater within a temperature range of 10.8℃ to 30.5℃.Mass balance calculations indicated that COD utilization mainly occurred in the anoxic phase,accounting for 88.2% of total COD removal.Ammonia nitrogen removal occurred 13.71% in the anoxic zones and 78.77% in the aerobic zones.The contribution of anoxic zones to total nitrogen（TN） removal was 57.41%.Results indicated that nitrogen elimination in the oxic tanks was mainly contributed by simultaneous nitrification and denitrification（SND）.The reduction of phosphorus mainly took place in the oxic zones,51.45% of the total removal.Denitrifying phosphorus removal was achieved biologically by 11.29%.Practical experience proved that adaptability to gradually changing temperature of the microbial populations was important to maintain the plant overall stability.Sudden changes in temperature did not cause paralysis of the system just lower removal efficiency,which could be explained by functional redundancy of microorganisms that may compensate the adverse effects of temperature changes to a certain degree.Anoxic-oxic process without internal recycling has great potential to treat low strength wastewater（i.e.,TN 〈 35 mg/L） as well as reducing operation costs.展开更多
The combined submerged biofilm （ SBF）-activated sludge （AS） process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for ca...The combined submerged biofilm （ SBF）-activated sludge （AS） process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for carbonaceous substances, nitrogen and phosphorus which mainly took place in the combined SBF-AS biore- actor. The SBF-AS bioreactor was divided into pre-anoxic, anaerobic, anoxic and aerobic zones from inlet to outlet, in which fixed biofilm carriers were packed. Excellent performance had been obtained under normal operating conditions in more than one year of operation in Dong＇ e municipal WWTP, Shandong province, with mean removal efficiencies of BOD5 93.4%, COD 88%, SS 92%, NH4 - N 82. 1%, TP 75% and TN 66.7%, and quite high effluent quality such as BOD5 6 to 10 rag/L, COD 20 to 40 rag/L, SS 5 to 10 rag/L, TN 10 to 20 rag/L, NH4 - N 4 to 8 mg/L and TP 0. 6 to 1.0 mg/L. The effluent was reused multi-purposely, such as toilet flushing, green belt watering and artificial lake pounding. Simultaneous nitrification and denitrification took place due to the DO gradient in biofilm in aerobic zone of the SBF-AS bioreactor, which made TN removal efficiency improved remarkably in system. Some activated sludge was returned from final clarifiers to the bioreactor for phosphorus removal. The process had the advantages of low investment and low operational/ maintenance （O/M） costs, low sludge yield and was preferably employed in small towns and cities.展开更多
An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly...An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.展开更多
A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved ...A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved oxygen （DO）, mixed liquor suspended solids （MLSS） and return activated sludge （RAS） recycle ratio. Remarkable simultaneous nitrification and denitrification （SND） was observed and mean total nitrogen （TN） removal efficiency up to 72.1% was steadily achieved, at DO concentration in the out, middle and inner channel of 0.1, 0.4 and 0.7 mg/L, respectively, with an average M LSS of 5.5 g/L and RAS recycle ratio of 150%. Although the out channel took the major role in TN removal, the role of middle channel should never be ignored. The denitrification potential could be fully developed under low DO, high MLSS with adequate RAS ratio. The sludge settleability was amazingly improved under low DO operation mode, and some explanations were tried. In addition, a scries of simplified batch tests were done to determine whether novel microorganisms could make substantial contribution to the performance of nitrogen removal. The results indicated that the SND observed in this Orbal oxidation ditch was more likely a physical phenomenon.展开更多
The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and...The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH_(3)^(−)-N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.展开更多
Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reductio...Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reduction using BTC with biozeolite was examined in a field incubation experiment in a eutrophic river in Yangzhou,Jiangsu Province,China.The biozeolite was zeolite with attached bacteria,including two isolated heterotrophic nitrifiers（Bacillus spp.）and two isolated aerobic denitrifiers（Acinetobacter spp.）.The results showed that the total nitrogen（TN）reduction efficiency of the overlying water by BTC with biozeolite（with thickness of about 2 mm）reached a maximum（56.69%）at day 34,and simultaneous heterotrophic nitrification and aerobic denitrification occurred in the BTC system until day 34.There was a significant difference in the TN concentrations of the overlying water between biozeolite capping and control（t-test;p〈0.05）.The biozeolite had very strong in situ bioregeneration ability.Carbon was the main source of nitrifier growth.However,both dissolved oxygen（DO）and carbon concentrations affected denitrifier growth.In particular,DO concentrations greater than 3 mg/L inhibited denitrifier growth.Therefore,BTC with biozeolite was found to be a feasible technique to reduce N in a eutrophic river.However,it is necessary to further strengthen the adaptability of aerobic denitrifiers through changing domestication methods or conditions.展开更多
基金Project supported by the Key International Cooperative Program of NSFC(No. 50521140075)the Hi-Tech Research and Development Program(863)of China(No. 2004AA601020)the Attached Projects of"863"Project of Beijing Municipal Science and Technology(No.20005186040421).
文摘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 denitrification 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 floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.
基金the National Key Project of Scientific and Technical Supporting Program of Ministry of Science and Technology ofChina(2006BAC19B03)Academic Human Resources Development in Institutions of Higher Leading under the Jurisdiction ofBeijing Municipalitythe Specialized Research Fund for the Doctoral Program of Higher Education of China(20060005002).
文摘Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated 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 programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency 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% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.
文摘The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...
基金Funded by the National Key Technologies R & D Program of China During the 10th Five-Year Plan Periods of China (No.2001BA604A01-03).
文摘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.
文摘The influence of main process parameters on simultaneous nitrification and denitrification （SND） in a sequencing batch reactor （SBR） were investigated while treating actual municipal sewage. The influent average concentration of CODcr and total nitrogen was 350mg-L-l and 35mg.L-l. The experiment indicated the following four operation control strategies： （1） When operation cycle was 6 hours, oxidation of organic pollutants and simultaneous nitrification and denitrification could well completed in the SBR reactor; （2） TN removal rate could be increased significantly, 40% higher than traditional SBR processes when idle period was set between influent and aeration; （3） The time of idle period could affect simultaneous nitrification and denitrification and the best time is 30 minutes; （4） Increase of sludge organic load may improve TN removal efficiency, but NH3-N removal efficiency declines.
基金supported by the Science Foundation Ireland(SFI)through the SFI Research Professorship Programme entitled"Innovative Energy Technologies for Biofuels,Bioenergy and a Sustainable Irish Bioeconomy"(IETSBIO3Grant No.15/RP/2763)the Research Infrastructure Research Grant Platform for Biofuel Analysis(Grant No.16/RI/3401).
文摘In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (FeSO4/Fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, Ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.
基金supported by the National High Technology Research Development Program (863) of China(No. 2007AA06A411)the Science and Technology Research Projects of Heilongjiang Education Committee(No. 11551130)
文摘For urban wastewater treatment,we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand（COD）,NH4＋-N,and total nitrogen（TN） removal performance.The removal rates of COD,NH4＋-N and TN were 88.2%,95.7%,and 86.4% with e？uent concentrations of COD,NH4＋-N and TN less than 50,8,and 10 mg/L,respectively.Biomass and bacterial activities were also measured,with results showing more nitrobacteria in the activated sludge than in the biofilm;however,bacterial activity of the biofilm biomass and the activated sludge were similar.Nitrogen concentrations during the process were also detected,with simultaneous nitrification and denitrification found to be obvious.
基金This work was supported by the National Natural Science Foundation of China for International Key Cooperation(Grant No.50521140075)the Key Laboratory Opening Foundation of Beijing.
文摘An aerobic sequencing batch biofilm reactor(SBBR)packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and deni-trification.The SBBR is advantageous for creating an anoxic condition,and the biofilm can absorb and store carbon for good nitrification and denitrification.An average concentra-tion 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 effluent TN concentra-tion increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L.The efficiency of simultaneous nitrification and denitrification(SND)increased with increasing thickness of the biofilm.The influent concen-tration 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.
文摘Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional 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 exam-ined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentra-tion is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7%with solids retention time(SRT)of 45 d,C/N value of 10,and F/M ratio of 0.1 g COD/(g MLSS·d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.
文摘To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobicanoxic oxidation ditch （OD）, where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification （SND） rate （rSND） was put forward to quantify SND. The results indicate that： （1） high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen （TN） and total phosphate （TP） removal rates were 80% and 85%, respectively; （2） when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; （3） the natural logarithm of the ratio of NOx to NH4^＋ in the effluent had a linear correlation to oxidation-reduction potential （ORP）; （4） when NO3^- was less than 6 mg/L, high phosphorus removal efficiency could be achieved; （5） denitrifying phosphorus removal （DNPR） could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.
基金Project supported by the New Century Excellent Talent Scholarship of China(No.NCET-05-0387)the Doctodal Unit Scholarship of China(No.20050247016).
文摘A lab-scale sequencing batch reactor （SBR） was set-up and the aerobic granular sludge was successfully incubated using anaerobic granular sludge as seed sludge. Nitrogen was partially removed by simultaneous nitrification and denitrification （SND） via nitrite with free ammonia （FA） of about 10 mg/L. The denaturing gradient gel electrophoresis （DGGE） method was used to investigate community structure of α-Proteobacteria, β-Proteobacteria, ammonia oxidizing bacteria （AOB）, and Nitrospira populations during start-up. The population sizes of bacteria, AOB and Nitrospira were examined using real-time PCR method. The analysis of community structure and Shannon index showed that stable structure of AOB population was obtained at day 35, while the communities of α- Proteobacteria, β-Proteobacteria, and Nitrospira became stable after day 45. At stable stage, the average cell densities were 1.1× 10^12, 2.2×10^10 and 1.0×10^10 cells/L for bacteria, AOB and Nitrospira, respectively. The relationship between characteristics of nitrifying bacteria community and nitrogenous substrate utilization constant was discussed by calculating Pearson correlation. Certain correlation seemed to exist between population size, biodiversity, and degradation constant. And the influence of population size might be greater than that of biodiversity.
文摘The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled conditions to proliferate the nitrifiers. Heterotrophic nitrifying bacteria were isolated from the system in which the efficiency of total nitrogen(TN) removal was up to 80%. Since no autotrophic ammonium and nitrite oxidizers could be detected by fluorescence in situ hybridization(FISH), oxidized-N production was unlikely to be catalyzed by autotrophic nitrifiers during the heterotrophic nitrifiers' isolation in this study. The batch test results indicate that the isolated heterotrophic bacteria were able to nitrify. After 3 weeks incubation, the efficiencies of the COD removal by the three isolated bacterial strains B1, B2, and B3 were 52 6%, 71 7%, and 77 7%, respectively. The efficiencies of the TN removal by B1, B2, and B3 were 35 6%, 61 2% and 68 7%, respectively.
基金Project(2009ZX07315-002-01) supported by the Water Pollution Control and Management of Major Special Science and Technology, China Project(CDJXS11210001) supported by the Scientific and Technical Innovation Project of Chongqing University Graduation Foundation, China
文摘To enhance the nitrogen removal,a systemic monitoring of the biological and hydrological parameters of Carrousel oxidation ditch in Chongqing Jingkou Wastewater Treatment Plant was carried out to study the feasibility of simultaneous nitrification and denitrification(SND).The variation and distribution of parameters such as flow velocity,concentration of dissolved oxygen(DO) and mixed liquor suspended solids(MLSS) in oxidation ditch were monitored and analyzed,which were major control factors for SND.The results showed that,the dimensional distribution of flow velocity,DO and MLSS were affected significantly by the operation condition of the aeration wheels.With all the four aeration wheels being in operation,DO and flow velocity were higher and the mixing of MLSS was sufficient.With three aeration wheels being in operation,the flow velocity in most of the bottom areas was enough to meet the basic requirements of no deposition,and the anaerobic region and aerobic region could exist simultaneously in one oxidation ditch,which was helpful to the process of SND.According to spatial distribution characteristics of the flow velocity,DO and soluble components under optimized condition,different functional zones of biochemical reaction in the Carrousel oxidation ditch system were defined,which might contribute to the optimization control and SND of Carrousel oxidation ditch.
基金supported by the National High Technology Research and Development Program (863 Program) of China (No. 2012AA063302)the Jiangsu Water Protection Project (No. 2015005)
文摘Performance of a full-scale anoxic-oxic activated sludge treatment plant（4.0×10-5 m-3/day for the first-stage project） was followed during a year.The plant performed well for the removal of carbon,nitrogen and phosphorus in the process of treating domestic wastewater within a temperature range of 10.8℃ to 30.5℃.Mass balance calculations indicated that COD utilization mainly occurred in the anoxic phase,accounting for 88.2% of total COD removal.Ammonia nitrogen removal occurred 13.71% in the anoxic zones and 78.77% in the aerobic zones.The contribution of anoxic zones to total nitrogen（TN） removal was 57.41%.Results indicated that nitrogen elimination in the oxic tanks was mainly contributed by simultaneous nitrification and denitrification（SND）.The reduction of phosphorus mainly took place in the oxic zones,51.45% of the total removal.Denitrifying phosphorus removal was achieved biologically by 11.29%.Practical experience proved that adaptability to gradually changing temperature of the microbial populations was important to maintain the plant overall stability.Sudden changes in temperature did not cause paralysis of the system just lower removal efficiency,which could be explained by functional redundancy of microorganisms that may compensate the adverse effects of temperature changes to a certain degree.Anoxic-oxic process without internal recycling has great potential to treat low strength wastewater（i.e.,TN 〈 35 mg/L） as well as reducing operation costs.
文摘The combined submerged biofilm （ SBF）-activated sludge （AS） process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for carbonaceous substances, nitrogen and phosphorus which mainly took place in the combined SBF-AS biore- actor. The SBF-AS bioreactor was divided into pre-anoxic, anaerobic, anoxic and aerobic zones from inlet to outlet, in which fixed biofilm carriers were packed. Excellent performance had been obtained under normal operating conditions in more than one year of operation in Dong＇ e municipal WWTP, Shandong province, with mean removal efficiencies of BOD5 93.4%, COD 88%, SS 92%, NH4 - N 82. 1%, TP 75% and TN 66.7%, and quite high effluent quality such as BOD5 6 to 10 rag/L, COD 20 to 40 rag/L, SS 5 to 10 rag/L, TN 10 to 20 rag/L, NH4 - N 4 to 8 mg/L and TP 0. 6 to 1.0 mg/L. The effluent was reused multi-purposely, such as toilet flushing, green belt watering and artificial lake pounding. Simultaneous nitrification and denitrification took place due to the DO gradient in biofilm in aerobic zone of the SBF-AS bioreactor, which made TN removal efficiency improved remarkably in system. Some activated sludge was returned from final clarifiers to the bioreactor for phosphorus removal. The process had the advantages of low investment and low operational/ maintenance （O/M） costs, low sludge yield and was preferably employed in small towns and cities.
基金Project (50278101) supported by the National Natural Science Foundation of China Project( CSTC, 2005AB7030)supported by Chongqing Key Technologies Research and Development Program
文摘An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.
基金The Key International Cooperative Programs of National Natural Science Foundation of China (No. 50521140075) and the NationalNatural Science Foundation of China (No. 50478040)
文摘A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved oxygen （DO）, mixed liquor suspended solids （MLSS） and return activated sludge （RAS） recycle ratio. Remarkable simultaneous nitrification and denitrification （SND） was observed and mean total nitrogen （TN） removal efficiency up to 72.1% was steadily achieved, at DO concentration in the out, middle and inner channel of 0.1, 0.4 and 0.7 mg/L, respectively, with an average M LSS of 5.5 g/L and RAS recycle ratio of 150%. Although the out channel took the major role in TN removal, the role of middle channel should never be ignored. The denitrification potential could be fully developed under low DO, high MLSS with adequate RAS ratio. The sludge settleability was amazingly improved under low DO operation mode, and some explanations were tried. In addition, a scries of simplified batch tests were done to determine whether novel microorganisms could make substantial contribution to the performance of nitrogen removal. The results indicated that the SND observed in this Orbal oxidation ditch was more likely a physical phenomenon.
基金This work was supported by the Foundation for Young Teachers of Dalian University of Technology(Grant No.2002120113)the Specialized Research Foundation for the Doctoral Program of Higher Education of the Ministry of Education of China(Grant No.20030141022).
文摘The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH_(3)^(−)-N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.
基金supported by the National Science and Technology Pillar Program(No.2012BAC04B02)the National Natural Science Fund of China(No.51408243)+3 种基金the Natural Science Foundation of Fujian Province of China(No.2015J01213)the Fundamental Research Funds for Central Universities(No.11QZR07)the Science and Technology Plan Fund of Quanzhou City(No.2014Z218)the Research Funds of Huaqiao University(No.14BS216)
文摘Bioreactive thin-layer capping（BTC）with biozeolite provides a potential remediation design that can sustainably treat N contamination from sediment and overlying water in eutrophic water bodies.Nitrogen（N）reduction using BTC with biozeolite was examined in a field incubation experiment in a eutrophic river in Yangzhou,Jiangsu Province,China.The biozeolite was zeolite with attached bacteria,including two isolated heterotrophic nitrifiers（Bacillus spp.）and two isolated aerobic denitrifiers（Acinetobacter spp.）.The results showed that the total nitrogen（TN）reduction efficiency of the overlying water by BTC with biozeolite（with thickness of about 2 mm）reached a maximum（56.69%）at day 34,and simultaneous heterotrophic nitrification and aerobic denitrification occurred in the BTC system until day 34.There was a significant difference in the TN concentrations of the overlying water between biozeolite capping and control（t-test;p〈0.05）.The biozeolite had very strong in situ bioregeneration ability.Carbon was the main source of nitrifier growth.However,both dissolved oxygen（DO）and carbon concentrations affected denitrifier growth.In particular,DO concentrations greater than 3 mg/L inhibited denitrifier growth.Therefore,BTC with biozeolite was found to be a feasible technique to reduce N in a eutrophic river.However,it is necessary to further strengthen the adaptability of aerobic denitrifiers through changing domestication methods or conditions.
