Constructed wetlands(CWs) are a promising method to treat effluent from wastewater treatment plants(WWTPs),However,low carbon/nitrogen(C/N) ratios of the influent inhibit denitrification in CWs,resulting in poor nitro...Constructed wetlands(CWs) are a promising method to treat effluent from wastewater treatment plants(WWTPs),However,low carbon/nitrogen(C/N) ratios of the influent inhibit denitrification in CWs,resulting in poor nitrogen removal efficiency.Herein,we compared traditional(control),biochar(BC), andβ-cyclodextrin-fu nctionalized biochar(BC@β-CD) CW systems to investigate nitrogen removal from influent with low C/N ratios,and the mechanisms that enhance this process.The highest nitrogen removal rates were observed in the BC@β-CD group,with rates 45.89% and 42.48% higher than those of the control,accompanied by a 70.57% and 85.45% decrease in nitrous oxide release,when the C/N ratio decreased from4 to 2,respectively.Metagenomic and enzymatic analyses indicated that BC@β-CD enhances nitrogen removal by coordinately promoting carbon metabolism and increasing denitrification enzyme activities,without affecting microbial species diversity in CWs.Structural equation modeling confirmed that the foremost advantages of BC@β-CD were effective electron generation and transportation resulting from increased activities of nicotinamide adenine dinucleotide(NADH) dehydrogenase and the electron transfer system(ETS),thereby strategically reallocating more carbon metabolic flow to support denitrification.Our results show that the application of BC@β-CD in CWs to optimize the reallocation of electrons from carbon metabolism is a feasible strategy to enhance denitrification under low C/N conditions.展开更多
This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C...This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater.The results demonstrated that the SC-MEC system,operating under anaerobic conditions and devoid of any organic carbon source,exhibited exceptional performance in ammonia oxidation and total nitrogen(TN)removal when solely relying on ammonia nitrogen as the electron donor.Operating at a voltage of 1.8 V with a capacitance capacity of 30 F,ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day,in which 97%of ammonium nitrogen was converted to gaseous nitrogen.Furthermore,the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials.Cyclic voltammetry(CV)analysis showed the significantly enhanced electrochemical activity of the SCMEC system during the reaction process.Based on in-situ CV test results,itwas inferred that this enhancementwas associated with extracellular electron transfer mediators.Themicrobial community analysis revealed a process of synchronous nitrification and denitrification(SND)coupled with anammox,involvingmultiple genera,such as Candidatus Kuenenia,Nitrosomonas,Truepera,and Bosea.In conclusion,this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal,offering more feasible and economical solutions for addressing low C/N water pollution issues.展开更多
As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater h...As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater has always been challenging.In this study,a gel immobilized PN/D nitrogen removal process(GI-PN/D)was established.A 94 days pilot-scale experiment was conducted using real municipal wastewater with an ammonia concentration of 43.5±5.3mg N/L at a temperature range of 11.3–28.7◦C.The nitrogen removal performance and associated pathways,shifts in the microbial community as well as sludge yield were investigated.The results were as follows:the effluent TN and COD were 0.6±0.4mg/L and 31.1±3.8 mg/L respectively,and the NAR exceeding 95%.GI-PN/D achieved deep nitrogen removal ofmunicipalwastewater through stable PN without taking any othermeasures.The primary pathways for nitrogen removal were identified as denitrification,simultaneous nitrification-denitrification,and aerobic denitrification.High-throughput sequencing analysis revealed that the immobilized fillers facilitated the autonomous enrichment of functional bacteria in each reactor,effectively promoting the dominance and stability of the microbial communities.In addition,GI-PN/D had the characteristic of low sludge yield,with an average sludge yield of 0.029 kg SS/kg COD.This study provides an effective technical for nitrogen removal from municipal wastewater through PN.展开更多
The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the eff...The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the effects of ammonia nitrogen(NH_(4)^(+)-N)concentrations on NP toxicity and AHL regulation have seldom been addressed yet.This study consulted on the impacts of ZnO NPs on BNR systems when high NH_(4)^(+)-N concentrationwas available.The synergistic toxic effects of high-strength NH_(4)^(+)-N(200 mg/L)and ZnO NPs resulted in decreased ammonia oxidation rates and dropped the nitrogen removal efficiencies by 17.5%±0.2%.The increased extracellular polymeric substances(EPS)production was observed in response to the high NH_(4)^(+)-N and ZnO NP stress,which indicated the defensemechanism against the toxic effects in the BNR systemswas stimulated.Furthermore,the regulatory effects of exogenous N-decanoyl-homoserine lactone(C_(10)-HSL)-mediated QS system on NP-stressed BNR systems were revealed to improve the BNR performance under different NH_(4)^(+)-N concentrations.The C_(10)-HSL regulated the intracellular reactive oxygen species levels,denitrification functional enzyme activities,and antioxidant enzyme activities,respectively.This probably synergistically enhanced the defense mechanism against NP toxicity.However,compared to the low NH_(4)^(+)-N concentration of 60 mg/L,the efficacy of C_(10)-HSL was inhibited at high NH_(4)^(+)-N levels of 200 mg/L.The findings provided the significant application potential of QS system for BNR when facing toxic compound shock threats.展开更多
The use of microalgae to recover nitrogen and phosphorus from wastewater has garnered significant attention,positioning it as one of the most promising and sustainable strategies in modern wastewater treatment.While v...The use of microalgae to recover nitrogen and phosphorus from wastewater has garnered significant attention,positioning it as one of the most promising and sustainable strategies in modern wastewater treatment.While various photobioreactors(PBRs)configurations have been widely applied for microalgae cultivation,limited research has focused on optimizing PBR design specificallyto enhance nitrogen and phosphorus removal efficiency.The high operational costs of wastewater treatment,combined with the inherent variability of microalgal growth,have prompted the search for advanced solutions that improve nitrogen and phosphorus removal while minimizing resource consumption and enabling predictive process control.Recently,the integration of PBR systems with artificialintelligence and machine learning(AI/ML)modeling has emerged as a transformative approach to enhancing nutrient removal,particularly for nitrogen and phosphorus.This study firstsummarizes existing PBR designs tailored for diverse applications,then outlines strategies for system enhancement through the optimization of mixing methods,construction materials,light intensity,and light source configuration.Furthermore,computational fluiddynamics(CFD)and AI/ML modeling are presented as tools to guide the structural design and operational optimization of microalgae-based nitrogen and phosphorus removal processes.Finally,future research directions and key challenges are discussed.展开更多
Two biological nitrogen removal processes are compared in the aspect of nitrogen removal, process operation and energy saving. Results show that when the returned sludge ratio is 50% of the inflow rate, the step-feedi...Two biological nitrogen removal processes are compared in the aspect of nitrogen removal, process operation and energy saving. Results show that when the returned sludge ratio is 50% of the inflow rate, the step-feeding process achieves over 80% total nitrogen （TN） removal efficiency, but the TN removal efficiency of the A/O process is only 40%. Moreover, filamentous sludge bulking can be well restrained in the step-feeding process. Given the conditions of a returned sludge ratio of 100% and a nitrifying liquor recycle ratio of 200%, the TN removal efficiency is 78.32% in the A/O process, but the sludge volume index （SVI） value increases to 143 mL/g. In the step-feeding process, the SVI is only 94.4 mL/g when the TN removal efficiency reaches 81. 1%. The step-feeding process has distinct advantages over the A/O process in the aspects of practicability, nitrogen removal and operating stability.展开更多
[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen re...[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.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
Sulfur-driven autotrophic denitrification(SDAD),a process suited for the treatment of nitrogen and sulfur-polluted wastewater without extra supplement of organic carbon,is a promising biological nitrogen removal proce...Sulfur-driven autotrophic denitrification(SDAD),a process suited for the treatment of nitrogen and sulfur-polluted wastewater without extra supplement of organic carbon,is a promising biological nitrogen removal process.However,the SDAD process was affected by many factors such as various electron donors,organic carbon and exogenous substances(e.g.,antibiotics and heavy metal),which prevent further application.Thus,we conducted a detailed review of previous studies on such influence factors and its current application.Besides,a comparative analysis was adopted to recognize the current challenges and future needs for feasible application,so as to ultimately perfect the SDAD process and extend its application scope.展开更多
In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux bi...In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device,and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control environment were explored.The results showed that as the seasonal temperature decreased from 34℃to 11.3℃,the total nitrogen removal rate of the DN-PN-Anammox system gradually decreased from the peak value of 1.42 kg/(m^(3)·day)to 0.49 kg/(m^(3)·day).At low temperatures(<20℃),when the nitrogen load(NLR)of the system is not appropriate,the fluctuation of high NH_(4)^(+)-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal.At temperatures of 11℃–15℃,the NLR of the system is controlled below 0.5 kg/(m^(3)·day),which can achieve stable nitrogen removal and the nitrogen removal efficiency can reach above 96%.The abundance of Candidatus Brocadia gradually increased with the decrease of temperature.Nitrosomonas,Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature.展开更多
A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow ...A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.展开更多
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
The stability and parameters of a bio-ceramic filter for completely autotrophic nitrogen removal were investigated. The completely autotrophic nitrogen removal over nitrite （CANON） reactor was fed with different con...The stability and parameters of a bio-ceramic filter for completely autotrophic nitrogen removal were investigated. The completely autotrophic nitrogen removal over nitrite （CANON） reactor was fed with different concentrations of ammonia （400, 300, and 200 mg N/L） but constant influent ammonia load. The results showed that the CANON system can achieve good treatment performance at ambient temperature （15-23℃）. The average removal rate and removal loading of NH4＋-N and TN was 83.90%, 1.26 kg N/（m3.day）, and 70.14%, 1.09 kg N/（m3.day）, respectively. Among the influencing factors like pH, dissolved oxygen and alkalinity, it was indicated that the pH was the key parameter of the performance of the CANON system. Observing the variation of pH would contribute to better control of the CANON system in an intuitive and fast way. Denaturing gradient gel electrophoresis analysis of microorganisms further revealed that there were some significant changes in the community structure of ammonium oxidizing bacteria, which had low diversity in different stages, while the species of anaerobic ammonium oxidizing （anammox） bacteria were fewer and the community composition was relatively stable. These observations showed that anaerobic ammonia oxidation was more stable than the aerobic ammonia oxidation, which could explain that why the CANON system maintained a good removal efficiency under the changing substrate conditions.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
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 effects of different chemical oxygen demand(COD)concentrations on the anammox granular sludge with Bamboo Charcoal(BC)addition were evaluated in UASB reactor.The results showed that the average total nitrogen(TN)r...The effects of different chemical oxygen demand(COD)concentrations on the anammox granular sludge with Bamboo Charcoal(BC)addition were evaluated in UASB reactor.The results showed that the average total nitrogen(TN)removal efficiency was reduced from 85.9%to 81.4%when COD concentration was increased from 50 to 150 mg/L.However,the TN removal efficiency of BC addition reactors was dramatically 3.1%-6.4%higher than that without BC under different COD concentrations.The average diameter of granular sludge was 0.13 mm higher than that without BC.The settling velocity was increased by elevated COD concentration,while the EPS and VSS/SS were increased with BC addition.The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition,and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia.The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD,while the abundance of anammox related functional genes of decreased.The func-tional genes related to anammox was hydrazine synthase encoding genes(hzsA,hzsB and hzsB).The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L.The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase.It is interesting to note that BC addition greatly enriched the related func-tional genes of denitrification and anammox.展开更多
The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors（SBBRs）（denoted SBBR1 and SBBR2） ...The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors（SBBRs）（denoted SBBR1 and SBBR2） at different nitrogen loading rates（NLRs） varying from（0.24 ± 0.01） to（1.26 ± 0.02） g N/（L·day）. SBBR1 was operated in parallel with SBBR2, but SBBR1 was filled with polyurethane foam loaded tourmaline（TPU） carriers and another（SBBR2） filled with polyurethane foam（PU） carriers. Results obtained from this study showed that the excellent and stable performance of SBBR1 was obtained. Ammonia nitrogen removal and total nitrogen removal were higher in SBBR1 than that in SBBR2 with increase of NLR. At an NLR of（0.24 ± 0.01） g N/（L·day）, the majority of the spherical and elliptical bacteria were surrounded by the extracellular polymeric substance（EPS） and bacillus or filamentous bacteria in two SBBRs biofilms. When NLR increased to（1.26 ± 0.02） g N/（L·day）, the clusters were more obvious in the SBBR1 biofilm than that in the SBBR2 biofilm. Bacteria in SBBR1 were inclined to synthesis more EPS, and the formed EPS could protect the bacteria from free ammonia（FA） under extreme condition NLR（1.26 ± 0.02） g N/（L·day）. The results of polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial community similarity in SBBR2 decreased more obviously than that in SBBR1 with the increase of NLR, which the microbial community in SBBR1 was relatively stable.展开更多
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...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（NaCI） 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.展开更多
The impact of the organic carbon to nitrogen ratio （chemical oxygen demand （COD）/N） in wastewater and dissolved oxygen （DO） concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia...The impact of the organic carbon to nitrogen ratio （chemical oxygen demand （COD）/N） in wastewater and dissolved oxygen （DO） concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria （AOB） communities in activated sludge in constantly aerated sequencing batch reactors （SBRs） was determined. At DO of 0.5 and 1.5 mg O2/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination （above 50%） was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O2/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O2/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.展开更多
A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operati...A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operation mode on the system performance and to develop a feasible control strategy. Results obtained from fixed-time control study indicate that the variations of the pH and oxidation-reduction potential（ORP） profiles can represent dynamic characteristics of system and the cycle sequences can be controlled and optimized by the control points on the pH and ORP profiles. A control strategy was, therefore, developed and applied to real-time control mode. Compared with traditional mode, the total nitrogen（TN） removal can be increased by approximately 16% in modified mode and a mean TN removal of 92% was achieved in real-time control mode. Moreover, approximately 12.5% aeration energy was saved in real- time control mode. The result of this study shows that the performance of nitrogen removal was enhanced in modified operation mode. Moreover, the real-time control made it possible to optimize process operation and save aeration energy.展开更多
基金supported by the National Natural Science Foundation of China(52321005)the Guangdong Basic and Applied Basic Research Foundation(2023A1515012383 and 2024A1515030138)+1 种基金the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology,2021TS30)the Shenzhen Science and Technology Program(KQTD20190929172630447 and KCXFZ20211020163404007).
文摘Constructed wetlands(CWs) are a promising method to treat effluent from wastewater treatment plants(WWTPs),However,low carbon/nitrogen(C/N) ratios of the influent inhibit denitrification in CWs,resulting in poor nitrogen removal efficiency.Herein,we compared traditional(control),biochar(BC), andβ-cyclodextrin-fu nctionalized biochar(BC@β-CD) CW systems to investigate nitrogen removal from influent with low C/N ratios,and the mechanisms that enhance this process.The highest nitrogen removal rates were observed in the BC@β-CD group,with rates 45.89% and 42.48% higher than those of the control,accompanied by a 70.57% and 85.45% decrease in nitrous oxide release,when the C/N ratio decreased from4 to 2,respectively.Metagenomic and enzymatic analyses indicated that BC@β-CD enhances nitrogen removal by coordinately promoting carbon metabolism and increasing denitrification enzyme activities,without affecting microbial species diversity in CWs.Structural equation modeling confirmed that the foremost advantages of BC@β-CD were effective electron generation and transportation resulting from increased activities of nicotinamide adenine dinucleotide(NADH) dehydrogenase and the electron transfer system(ETS),thereby strategically reallocating more carbon metabolic flow to support denitrification.Our results show that the application of BC@β-CD in CWs to optimize the reallocation of electrons from carbon metabolism is a feasible strategy to enhance denitrification under low C/N conditions.
基金supported by the National Natural Science Foundation of China(No.31970106).
文摘This study presents a novel approach,the Supercapacitor Microbial Electrolysis Cell(SCMEC),which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater.The results demonstrated that the SC-MEC system,operating under anaerobic conditions and devoid of any organic carbon source,exhibited exceptional performance in ammonia oxidation and total nitrogen(TN)removal when solely relying on ammonia nitrogen as the electron donor.Operating at a voltage of 1.8 V with a capacitance capacity of 30 F,ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day,in which 97%of ammonium nitrogen was converted to gaseous nitrogen.Furthermore,the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials.Cyclic voltammetry(CV)analysis showed the significantly enhanced electrochemical activity of the SCMEC system during the reaction process.Based on in-situ CV test results,itwas inferred that this enhancementwas associated with extracellular electron transfer mediators.Themicrobial community analysis revealed a process of synchronous nitrification and denitrification(SND)coupled with anammox,involvingmultiple genera,such as Candidatus Kuenenia,Nitrosomonas,Truepera,and Bosea.In conclusion,this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal,offering more feasible and economical solutions for addressing low C/N water pollution issues.
基金supported by Beijing Municipal Commission of Education(No.Z161100004516015)the Open Project Program of Hebei Center for Ecological and Environmental Geology Research(No.JSYF-202304).
文摘As an energy and carbon saving process for nitrogen removal from wastewater,the partial nitrification and denitrification process(PN/D)has been extensively researched.However,achieving stable PNinmunicipalwastewater has always been challenging.In this study,a gel immobilized PN/D nitrogen removal process(GI-PN/D)was established.A 94 days pilot-scale experiment was conducted using real municipal wastewater with an ammonia concentration of 43.5±5.3mg N/L at a temperature range of 11.3–28.7◦C.The nitrogen removal performance and associated pathways,shifts in the microbial community as well as sludge yield were investigated.The results were as follows:the effluent TN and COD were 0.6±0.4mg/L and 31.1±3.8 mg/L respectively,and the NAR exceeding 95%.GI-PN/D achieved deep nitrogen removal ofmunicipalwastewater through stable PN without taking any othermeasures.The primary pathways for nitrogen removal were identified as denitrification,simultaneous nitrification-denitrification,and aerobic denitrification.High-throughput sequencing analysis revealed that the immobilized fillers facilitated the autonomous enrichment of functional bacteria in each reactor,effectively promoting the dominance and stability of the microbial communities.In addition,GI-PN/D had the characteristic of low sludge yield,with an average sludge yield of 0.029 kg SS/kg COD.This study provides an effective technical for nitrogen removal from municipal wastewater through PN.
基金supported by the National Natural Science Foundation of China(No.52270119).
文摘The inhibitory effects of zinc oxide nanoparticles(ZnO NPs)and impacts of N-acylhomoserine lactone(AHL)-based quorum sensing(QS)on biological nitrogen removal(BNR)performance have beenwell-investigated.However,the effects of ammonia nitrogen(NH_(4)^(+)-N)concentrations on NP toxicity and AHL regulation have seldom been addressed yet.This study consulted on the impacts of ZnO NPs on BNR systems when high NH_(4)^(+)-N concentrationwas available.The synergistic toxic effects of high-strength NH_(4)^(+)-N(200 mg/L)and ZnO NPs resulted in decreased ammonia oxidation rates and dropped the nitrogen removal efficiencies by 17.5%±0.2%.The increased extracellular polymeric substances(EPS)production was observed in response to the high NH_(4)^(+)-N and ZnO NP stress,which indicated the defensemechanism against the toxic effects in the BNR systemswas stimulated.Furthermore,the regulatory effects of exogenous N-decanoyl-homoserine lactone(C_(10)-HSL)-mediated QS system on NP-stressed BNR systems were revealed to improve the BNR performance under different NH_(4)^(+)-N concentrations.The C_(10)-HSL regulated the intracellular reactive oxygen species levels,denitrification functional enzyme activities,and antioxidant enzyme activities,respectively.This probably synergistically enhanced the defense mechanism against NP toxicity.However,compared to the low NH_(4)^(+)-N concentration of 60 mg/L,the efficacy of C_(10)-HSL was inhibited at high NH_(4)^(+)-N levels of 200 mg/L.The findings provided the significant application potential of QS system for BNR when facing toxic compound shock threats.
基金supported by the National Natural Science Foundation of China(22038012,U24A20543)the Science and Technology Pro-gram of Fujian Province,China(2025Y4001).
文摘The use of microalgae to recover nitrogen and phosphorus from wastewater has garnered significant attention,positioning it as one of the most promising and sustainable strategies in modern wastewater treatment.While various photobioreactors(PBRs)configurations have been widely applied for microalgae cultivation,limited research has focused on optimizing PBR design specificallyto enhance nitrogen and phosphorus removal efficiency.The high operational costs of wastewater treatment,combined with the inherent variability of microalgal growth,have prompted the search for advanced solutions that improve nitrogen and phosphorus removal while minimizing resource consumption and enabling predictive process control.Recently,the integration of PBR systems with artificialintelligence and machine learning(AI/ML)modeling has emerged as a transformative approach to enhancing nutrient removal,particularly for nitrogen and phosphorus.This study firstsummarizes existing PBR designs tailored for diverse applications,then outlines strategies for system enhancement through the optimization of mixing methods,construction materials,light intensity,and light source configuration.Furthermore,computational fluiddynamics(CFD)and AI/ML modeling are presented as tools to guide the structural design and operational optimization of microalgae-based nitrogen and phosphorus removal processes.Finally,future research directions and key challenges are discussed.
基金The Project of Scientific Research Base and Scientific Innovation Platform of Beijing Municipal Education Commission (No.PXM2008-014204-050843)the Project of Beijing Science and Technology Committee (No.D07050601500000)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (No.RCEES-QN-200706)the Special Funds for Young Scholars of RCEES,CAS.
文摘Two biological nitrogen removal processes are compared in the aspect of nitrogen removal, process operation and energy saving. Results show that when the returned sludge ratio is 50% of the inflow rate, the step-feeding process achieves over 80% total nitrogen （TN） removal efficiency, but the TN removal efficiency of the A/O process is only 40%. Moreover, filamentous sludge bulking can be well restrained in the step-feeding process. Given the conditions of a returned sludge ratio of 100% and a nitrifying liquor recycle ratio of 200%, the TN removal efficiency is 78.32% in the A/O process, but the sludge volume index （SVI） value increases to 143 mL/g. In the step-feeding process, the SVI is only 94.4 mL/g when the TN removal efficiency reaches 81. 1%. The step-feeding process has distinct advantages over the A/O process in the aspects of practicability, nitrogen removal and operating stability.
基金Supported by the National Science Foundation for Young Scientists of China(51108196)the FDYT in Higher Education of Guangdong,China(LYM10034)+1 种基金the Natural Science Foundation of Guangdong Province,China(S2011040001251)the Key Laboratory Fund of Ecological Agriculture of Ministry of Agriculture of China(2010-LH12)~~
文摘[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.
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the financial support from the National Natural Science Foundation of China(No.51878231)。
文摘Sulfur-driven autotrophic denitrification(SDAD),a process suited for the treatment of nitrogen and sulfur-polluted wastewater without extra supplement of organic carbon,is a promising biological nitrogen removal process.However,the SDAD process was affected by many factors such as various electron donors,organic carbon and exogenous substances(e.g.,antibiotics and heavy metal),which prevent further application.Thus,we conducted a detailed review of previous studies on such influence factors and its current application.Besides,a comparative analysis was adopted to recognize the current challenges and future needs for feasible application,so as to ultimately perfect the SDAD process and extend its application scope.
基金supported by the Natural Science Foundation of China(No.51938010)the Suzhou Science and Technology Plan Project-Minsheng Project(No.SS201804-02)+1 种基金National Key Research and Development Programme of China(No.2016YFC 0401103)the Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment。
文摘In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device,and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control environment were explored.The results showed that as the seasonal temperature decreased from 34℃to 11.3℃,the total nitrogen removal rate of the DN-PN-Anammox system gradually decreased from the peak value of 1.42 kg/(m^(3)·day)to 0.49 kg/(m^(3)·day).At low temperatures(<20℃),when the nitrogen load(NLR)of the system is not appropriate,the fluctuation of high NH_(4)^(+)-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal.At temperatures of 11℃–15℃,the NLR of the system is controlled below 0.5 kg/(m^(3)·day),which can achieve stable nitrogen removal and the nitrogen removal efficiency can reach above 96%.The abundance of Candidatus Brocadia gradually increased with the decrease of temperature.Nitrosomonas,Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature.
基金supported by the Special Fundof State Key Joint Laboratory of Environment Simulation and Pollution Control,China (No. 08Y03ESPCT)the Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-Year Plan Period of China(No. 2006BACl9B01)
文摘A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.
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supported by the Trans-Century Training Program Foundation for Talents from the Ministry of Education of China (No. NCET-10-0008)the Open Project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology (No.QAK201005)the National Water Pollution Control and Management Technology Major Projects (No.2012ZX07202-005)
文摘The stability and parameters of a bio-ceramic filter for completely autotrophic nitrogen removal were investigated. The completely autotrophic nitrogen removal over nitrite （CANON） reactor was fed with different concentrations of ammonia （400, 300, and 200 mg N/L） but constant influent ammonia load. The results showed that the CANON system can achieve good treatment performance at ambient temperature （15-23℃）. The average removal rate and removal loading of NH4＋-N and TN was 83.90%, 1.26 kg N/（m3.day）, and 70.14%, 1.09 kg N/（m3.day）, respectively. Among the influencing factors like pH, dissolved oxygen and alkalinity, it was indicated that the pH was the key parameter of the performance of the CANON system. Observing the variation of pH would contribute to better control of the CANON system in an intuitive and fast way. Denaturing gradient gel electrophoresis analysis of microorganisms further revealed that there were some significant changes in the community structure of ammonium oxidizing bacteria, which had low diversity in different stages, while the species of anaerobic ammonium oxidizing （anammox） bacteria were fewer and the community composition was relatively stable. These observations showed that anaerobic ammonia oxidation was more stable than the aerobic ammonia oxidation, which could explain that why the CANON system maintained a good removal efficiency under the changing substrate conditions.
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.
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supported by the China Postdoctoral Science Foundation (No. 2020M671400)the Natural Science Foundation of Jiangsu Province (No. BK20201450)+3 种基金the Jiangsu Qing Lan ProjectSuzhou Science and Technology Planning Project (Nos.SS202016 and SS2019022)the Opening Fund of Jiangsu Provincial Key Laboratory of Environmental Science and Engineering(No. Zd1804)the Graduate Research Innovation Program of Jiangsu Province (No. KYCX19_2030)
文摘The effects of different chemical oxygen demand(COD)concentrations on the anammox granular sludge with Bamboo Charcoal(BC)addition were evaluated in UASB reactor.The results showed that the average total nitrogen(TN)removal efficiency was reduced from 85.9%to 81.4%when COD concentration was increased from 50 to 150 mg/L.However,the TN removal efficiency of BC addition reactors was dramatically 3.1%-6.4%higher than that without BC under different COD concentrations.The average diameter of granular sludge was 0.13 mm higher than that without BC.The settling velocity was increased by elevated COD concentration,while the EPS and VSS/SS were increased with BC addition.The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition,and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia.The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD,while the abundance of anammox related functional genes of decreased.The func-tional genes related to anammox was hydrazine synthase encoding genes(hzsA,hzsB and hzsB).The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L.The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase.It is interesting to note that BC addition greatly enriched the related func-tional genes of denitrification and anammox.
基金supported by the Project of Nature Scientific Foundation of Heilongjiang Province (No. C2017037)the National Natural Science Foundation of China (No. 31501839)
文摘The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors（SBBRs）（denoted SBBR1 and SBBR2） at different nitrogen loading rates（NLRs） varying from（0.24 ± 0.01） to（1.26 ± 0.02） g N/（L·day）. SBBR1 was operated in parallel with SBBR2, but SBBR1 was filled with polyurethane foam loaded tourmaline（TPU） carriers and another（SBBR2） filled with polyurethane foam（PU） carriers. Results obtained from this study showed that the excellent and stable performance of SBBR1 was obtained. Ammonia nitrogen removal and total nitrogen removal were higher in SBBR1 than that in SBBR2 with increase of NLR. At an NLR of（0.24 ± 0.01） g N/（L·day）, the majority of the spherical and elliptical bacteria were surrounded by the extracellular polymeric substance（EPS） and bacillus or filamentous bacteria in two SBBRs biofilms. When NLR increased to（1.26 ± 0.02） g N/（L·day）, the clusters were more obvious in the SBBR1 biofilm than that in the SBBR2 biofilm. Bacteria in SBBR1 were inclined to synthesis more EPS, and the formed EPS could protect the bacteria from free ammonia（FA） under extreme condition NLR（1.26 ± 0.02） g N/（L·day）. The results of polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial community similarity in SBBR2 decreased more obviously than that in SBBR1 with the increase of NLR, which the microbial community in SBBR1 was relatively stable.
基金The Hi_Tech Research and Development Program(863) of China(2004AA601020) the National Natural Science Foundation of China(No.50478047)andthe Open Grant of Beijing Key Laboratory
文摘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（NaCI） 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.
文摘The impact of the organic carbon to nitrogen ratio （chemical oxygen demand （COD）/N） in wastewater and dissolved oxygen （DO） concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria （AOB） communities in activated sludge in constantly aerated sequencing batch reactors （SBRs） was determined. At DO of 0.5 and 1.5 mg O2/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination （above 50%） was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O2/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O2/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.
基金The Project of Beijing Science and Technology Committee (No.020620010120) ,the Hi_Tech Research and Development Program(863) of China (No.2004AA601020) ,the Project under Key International Cooperative Programs of NSFC(No.50521140075) and the Project of Key Laboratory of Beiing
文摘A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operation mode on the system performance and to develop a feasible control strategy. Results obtained from fixed-time control study indicate that the variations of the pH and oxidation-reduction potential（ORP） profiles can represent dynamic characteristics of system and the cycle sequences can be controlled and optimized by the control points on the pH and ORP profiles. A control strategy was, therefore, developed and applied to real-time control mode. Compared with traditional mode, the total nitrogen（TN） removal can be increased by approximately 16% in modified mode and a mean TN removal of 92% was achieved in real-time control mode. Moreover, approximately 12.5% aeration energy was saved in real- time control mode. The result of this study shows that the performance of nitrogen removal was enhanced in modified operation mode. Moreover, the real-time control made it possible to optimize process operation and save aeration energy.
