Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

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.

Theoretical evaluation on nitrogen removal of step-feed anoxic/oxic activated sludge process

Evaluation on nitrogen removal of step-feed anoxic/oxic activated sludge process at the standpoint of reaction kinetics and process kinetics was conducted. Theoretical biological nitrogen removal efficiency was deduced based on the mass balance of nitrate in the last stage. The comparison of pre-denitrification process and step feed process in the aspects of nitrogen removal efficiency, volume of reactor and building investment was studied, and the results indicated that step-feed anoxic/oxic activated sludge process was superior to pre-denitrification process in these aspects.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Effect of initial ammonium concentration on a one-stage partial nitrification/anammox biofilm system:Nitrogen removal performance and the microbial community

One-stage partial nitrification coupled with anammox(PN/A)technology effectively reduces the energy consumption of a biological nitrogen removal system.Inhibiting nitrite-oxidizing bacteria(NOB)is essential for this technology to maintain efficient nitrogen removal performance.Initial ammonium concentration(IAC)affects the degree of inhibited NOB.In this study,the effect of the IAC on a PN/A biofilm was investigated in a moving bed biofilm reactor.The results showed that nitrogen removal efficiency decreased from 82.49%±1.90%to 64.57%±3.96%after the IAC was reduced from 60 to 20 mg N/L,while the nitrate production ratio increased from 13.87%±0.90%to 26.50%±3.76%.NOB activity increased to1,133.86 mg N/m^(2)/day after the IAC decreased,approximately 4-fold,indicating that the IAC plays an important inhibitory role in NOB.The rate-limiting step in the mature biofilm of the PN/A system is the nitritation process and is not shifted by the IAC.The analysis of the microbial community structure in the biofilm indicates that the IAC was the dominant factor in changes in community structure.Ca.Brocadia and Ca.Jettenia were the main anammox bacteria,and Nitrosomonas and Nitrospira were the main AOB and NOB,respectively.IAC did not affect the difference in growth between Ca.Brocadia and Ca.Jettenia.Thus,modulating the IAC promoted the PN/A process with efficient nitrogen removal performance at medium to low ammonium concentrations.

Insights into a novel nitrogen removal process based on simultaneous anammox and denitrification(SAD) following nitritation with in-situ NOB elimination

Simultaneous anammox and denitrification(SAD) is an efficient approach to treat wastewater having a low C/N ratio;however, few studies have investigated a combination of SAD and partial nitritation(PN). In this study, a lab-scale up-flow blanket filter(UBF) and zeolite sequence batch reactor(ZSBR) were continuously operated to implement SAD and PN advantages, respectively. The UBF achieved a high total nitrogen(TN) removal efficiency of over 70% during the start-up stage(days 1–50), and reached a TN removal efficiency of 96%in the following 90 days(days 51–140) at COD/NH_(4)^(+)-N ratio of 2.5. The absolute abundance of anammox bateria increased to the highest value of 1.58 × 107copies/μL DNA;Comamonadaceae was predominant in the UBF at the optimal ratio. Meanwhile, ZSBR was initiated on day 115 as fast nitritation process to satisfy the influent requirement for the UBF. The combined process was started on day 140 and then lasted for 30 days, during the combined process, between the two reactors, the UBF was the main contributor for TN(66.5% ± 4.5%)and COD(71.8% ± 4.9%) removal. These results demonstrated that strong SAD occurred in the UBF when following a ZSBR with in-situ NOB elimination. This research presents insights into a novel biological nitrogen removal process for low C/N ratio wastewater treatment.

An efficient way to enhance the total nitrogen removal efficiency of the Anammox process by S^0-based short-cut autotrophic denitrification

In order to reduce the amount of NO_3^-–N generated by the Anammox process, and alleviate the competition between denitrification and Anammox for NO_2^-–N in a single reactor, the preference of S^0 for reacting with coexisting NO_2^-–N and NO_3^-–N in the sulfur autotrophic denitrifying(SADN) process and the coupling effect of short-cut SADN and the Anammox process were studied. The results showed that S^0 preferentially reacted with NO_3^-to produce NO_2^-–N, and then reacted with NO_2^-–N when NO_3^-–N was insufficient, which could effectively alleviate the competition between SADN bacteria(SADNB) and Anammox bacteria(An AOB) for NO_2^-–N. After 170 days of operation, coupling between short-cut S^0-SADN and the Anammox process was first successfully achieved. SADNB converted the NO_3^-–N generated by the Anammox process into NO_2^-–N, which was once again available to An AOB. The total nitrogen removal efficiency eventually stabilized at over 95%, and the effluent NO_3^-–N was controlled within 10 mg/L, when high NH_4^+–N wastewater was treated by the Anammox process. Microbial community analysis further showed that Candidatus Brocadia and Thiobacillus were the functional microorganisms for An AOB and SADNB.

Performance of a completely autotrophic nitrogen removal over nitrite process for treating wastewater with different substrates at ambient temperature

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.

Investigation of Nitrite Production Pathway in Integrated Partial Denitrification/Anammox Process via Isotope Labelling Technique and the Relevant Microbial Communities

In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA)process was investigated by using an UASB reactor.High total nitrogen(TN)removal efficiency(91.97%)was achieved at an influent nitrogen loading rate of 0.64 kg/(m3·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to ^(15)N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus_Brocadia,Candidatus_Kuenenia and Thauera were functional strains for anammox and denitrification process,respectively.Thauera and Candidatus_Brocadia were more important for TN removal at high loading rates(0.64 kg/(m3·d)).This result can provide a theoretical and technical foundation for the application of the PDA process.

聚对苯二甲酸乙二醇酯微塑料对Anammox颗粒污泥的尺寸影响效应

为探究微塑料(MPs)对活性污泥脱氮性能的尺寸影响效应,采用水质测定、活性测试、物化表征及微生物群落分析等方法,探索了不同粒径下(75~500μm)聚对苯二甲酸乙二醇酯(PET)对厌氧氨氧化颗粒污泥(AnGS)的影响.结果显示,投加75和150μm的PET-MPs时,Anammox脱氮效能低于控制组,而300和500μm组中却表现出优于控制组.厌氧氨氧化活性(SAA)测试具有相似结果.胞外聚合物(EPS)分析发现PET-MPs粒径越小,EPS分泌和PN/PS越高,AnGS结构越不完整.小粒径下PET对Anammox抑制主要与颗粒污泥所具有的较低Zeta电位和较小的比表面积显著相关.而大粒径PET-MPs则减少了与MPs接触的机率且能提供更多的活性位点,促进了Anammox底物的传递效率.高通量测序结果表明PET-MPs粒径大小决定了微生物群落的多样性和丰富度,尤其对Anammox菌属(Candidatus Kuenenia)相对丰度影响显著.

低氨氮质量浓度废水DPR-SNAD脱氮除磷效能研究

针对低氨氮废水单级自养脱氮系统副产物硝氮残留,有机物耐受能力差,以及缺乏除磷功能等问题,提出反硝化除磷(Denitrifying Phosphorus Removal,DPR)-单级自养脱氮(Simultaneous Partial Nitrification,Anaerobic Ammonium Oxidation and Denitrification,SNAD)组合处理技术,重点考察氨氮负荷对单级自养脱氮工艺(Single-stage Nitrogen Removal Using Anammox And Partial Nitritation,SNAP)系统、泥龄对DPR系统构建的影响,以及低氨氮废水DPR-SNAD组合处理系统的脱氮除磷效能与微生物种群。研究结果显示:采用氨氮质量浓度梯度递减方式,氨氮负荷为0.20 kg N/(m^(3)·d)的低氨氮质量浓度的SNAP系统构建时间为63 d,较负荷为0.05 kg N/(m^(3)·d)的系统缩短了37 d。泥龄对构建的DPR系统效能影响显著,泥龄为35 d的系统除磷脱氮效能较高,PO_(4)^(3-)-P、NO_(3)^(-)-N、COD去除率分别为86.25%、98.00%、92.00%,系统释磷、吸磷、反硝化脱氮速率分别达4.60 mg/(L·h)、4.13 mg/(L·h)、5.53 mg/(L·h)。DPR-SNAD组合处理系统的氨氮(NH_(4)^(+)-N)、总氮(Total Nitrogen,TN)、总磷(Total Phosphorus,TP)、化学需氧量(Chemical Oxygen Demand,COD)去除率分别为100%、98.64%、86.00%、93.30%。TN、TP去除率较对照组SNAP分别提高了19.20百分点和86.00百分点。16S rRNA高通量测序结果显示,组合系统脱氮除磷功能菌属主要有Rhodobacter、Candidatus_Brocadia、Nitrosomonas、Gemmobacter,SNAD系统中厌氧氨氧化菌(Anaerobic Ammonia Oxidation,AnAOB)相对丰度显著高于对照组SNAP系统,DPR促进SNAD提高了系统脱氮效能。

Advances and challenges of sulfur-driven autotrophic denitrification(SDAD)for nitrogen removal

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.

Combined biologic aerated filter and sulfur/ceramisite autotrophic denitrification for advanced wastewater nitrogen removal at low temperatures

An innovative advanced wastewater treatment process combining biologic aerated filter （BAF） and sulfur/ ceramisite-based autotrophic denitrification （SCAD） for reliable removal of nitrogen was proposed in this paper. In SCAD reactor, ceramisite was used as filter and Ca （HCO3）2 was used for supplying alkalinity and carbon source. The BAF-SCAD was used to treat the secondary treatment effluent. The performance of this process was investigated, and the impact of temperature on nitrogen removal was studied. Results showed that the combined system was effective in nitrogen removal even at low temperatures （8℃）. Removal of total nitrogen （TN）, NH4＋ -N, NO3-N reached above 90% at room temperature. Nitrification was affected by the temperature and nitrification at low temperature （8℃） was a limiting factor for TN removal. However, denitrification was not impacted by the temperature and the removal of NO3 -N maintained 98% during the experimental period. The reason of effective denitrification at low temperature might be the use of easily dissolved Ca（HCO3）2 and high-flux ceramisite, which solved the problem of low mass transfer efficiency at low temperatures. Besides, vast surface area of sulfur with diameter of 2-6 mm enhanced the rate of microbial utilization. The removal of nitrate companied with the production of SO42-, and the average concentration of SO27 was about 240mg.L^-1. These findings would be beneficial for the application of this process to nitrogen removal especially in the winter and cold regions.

常温ANAMMOX工艺运行性能及功能菌研究

通过改变进水基质浓度,对以火山岩为填料的常温上向流厌氧氨氧化生物滤池在不同基质浓度下的脱氮性能进行了研究.借助显微镜、电镜(SEM)观察对滤池内的微生物形态进行了分析,利用变性凝胶电泳(DGGE)和克隆测序等微生物方法,对ANAMMOX种属进行了鉴定.试验结果表明,常温条件下,厌氧氨氧化滤池在高、低不同基质下都能够保持较高的脱氮效果,其中TN去除负荷最高能够达到2.99kgN/(m3 d),NH4+-N和NO2--N最高去除率分别能够达到99.4%和98.8%;显微镜、电镜观察显示:滤池下部的微生物种类更丰富,ANAMMOX菌在滤池的中部和上部的比例更高;16SrRNA克隆测序鉴定结果表明:滤池中的ANAMMOX菌为Candidatus Kuenenia stuttgartiensis,其对温度和基质浓度都有着较宽的适应性.

A/O+Anammox工艺处理低C/N城市污水的脱氮性能

以低C/N城市污水为研究对象,研究A/O+Anammox工艺的脱氮特性。试验结果表明:A/O+Anammox工艺可实现高效脱氮;在进水总氮(TN)平均质量浓度为62.01 mg/L,溶解性COD/TN(C/N)为2.42的条件下,出水TN平均质量浓度为11.48 mg/L,NH4+-N平均质量浓度为1.83 mg/L,可以达到国家《城镇污水处理厂污染物排放标准》(GB18918—2002)一级A标准;A/O反应器中TN去除占该工艺TN去除量的51.13%,主要通过缺氧反硝化、好氧同步硝化反硝化和剩余污泥排放实现;AO反应器出水ρ(NO2--N)/ρ(NH4+-N)可控制在1.0左右,满足后续厌氧氨氧化对进水的要求。Anammox反应器TN去除量占该工艺TN去除量的48.87%;半亚硝化和厌氧氨氧化作用是A/O+Anammox工艺处理低C/N污水实现高效脱氮的关键原因。

新型生物脱氮技术及其相关酶系的研究进展

水中氮素浓度过高会导致水体富营养化,而新型生物脱氮技术有多种耦合手段,可以针对不同的氨氮浓度进行使用,因此在水体氮素污染处理领域具有广阔的应用前景。本文系统介绍了新型生物脱氮技术的反应通路、研究进展及优缺点;并对不同反应路径中生物脱氮酶的作用机制、酶活测定和研究现状等进行了系统的阐述,最后对新型生物脱氮通路上的生物脱氮酶进行总结归纳,对生物脱氮酶的未来提出展望。本综述旨在为提高新型生物脱氮技术在水体氮素处理中的效率及相关生物脱氮酶的研究提供理论依据。

低基质质量浓度条件下ANAMMOX生物滤池脱氮效果研究

研究了在低基质质量浓度条件下ANAMMOX生物滤池的脱氮效果.试验结果显示,NH_4^+-N的质量浓度在10～25 mg/L时,厌氧氨氧化滤池具有很高的基质去除率,NH_4^+-N的平均去除率为93.07%,NO_2^--N的平均去除率为82.23%,NO_2^--N与NH_4^+-N适宜的配比值为1.34,生物滤池脱氮高效段的滤池深度为0～60 cm.

微氧条件下培养AOB-Anammox颗粒污泥

采用絮状硝化污泥和厌氧氨氧化颗粒污泥为接种污泥,利用膨胀颗粒污泥床反应器,在微氧曝气条件下,培养自养脱氮(氨氧化AOB-厌氧氨氧化Anammox)颗粒污泥.在无机高氨氮进水条件下,维持反应器运行58 d,成功培养出AOB-Anammox颗粒污泥.在模拟生活污水条件下,颗粒污泥脱氮效果稳定,氨氮和总氮去除率最高可达92.3%、71.2%,平均总氮去除负荷达1.237 kg·N/(m^3·d).SEM及FISH结果表明:AOB-Anammox颗粒污泥微生物组成以2种菌群为主,AOB细菌密集排布于颗粒污泥表面,Anammox细菌均匀分布在颗粒污泥内部.

厌氧氨氧化(Anammox)工艺的强化方法研究进展

厌氧氨氧化(Anammox)工艺是一种经济高效的新型生物脱氮技术,但是Anammox菌倍增时间长、对环境条件敏感、易受各类污染物的抑制等劣势成为其推广应用的重要瓶颈,对Anammox工艺进行强化可以有效解决这一问题。本文从Anammox菌的富集(包括加速颗粒化、使用生物膜、采用膜生物反应器等)、添加化学物质(二氧化锰、氧化石墨烯、铁离子、Anammox中间产物等)、施加物理场(超声波、磁场、电场等)以及生物强化和菌种流加等方面,介绍了目前国内外关于Anammox工艺强化的研究进展,分析了技术要点,解析了强化机理,最后指出未来的研究方向应集中于强化参数的优化、不同强化策略的综合作用、强化的长期作用效果以及对强化机理的深入研究等方面。

基于ANAMMOX处理低C/N废水高效脱氮联合工艺研究进展

厌氧氨氧化作为一种高效低廉的生物脱氮技术,在高氨氮、低C/N比废水处理过程中显示出无比的优越性。但是,厌氧氨氧化反应过程中会生成大约11%的硝态氮,在处理高浓度含氨废水时,出水总氮可能达不到行业接管排放标准的要求。反硝化技术作为硝态氮脱除的有效手段,联合反硝化技术势必有利于提高氮素的去除率。针对生成的硝态氮问题,从碳源需求角度,基于短程硝化-厌氧氨氧化联合工艺与反硝化技术实现高效生物脱氮的工艺组合形式进行了介绍,提出了前置反硝化、半反硝化和后置反硝化联合脱氮工艺。并对这些组合工艺的特点、优劣及应用情况进行了简要分析。最后对厌氧氨氧化联合高效脱氮工艺运用于低C/N比废水处理的研究重点进行了展望。

基于碳减排的厌氧氨氧化脱氮工艺应用及强化调控进展

随着我国“双碳”目标的提出和水处理行业提标改造的重点落在生物脱氮,污水处理厂从关注满足排放许可限制转向实现碳中和、能量自给及资源回收。厌氧氨氧化(Anammox)技术凭借无需外加有机碳源、占地面积小、污泥产量少以及脱氮效率高等节能降耗与碳减排优势,代表着未来污水生物脱氮的发展方向。基于已有研究成果,梳理对比了传统脱氮与Anammox反应的发展历程;重点综述了新兴短程硝化耦合Anammox(PN-A)工艺、短程反硝化耦合Anammox(PD-A)工艺和甲烷型反硝化耦合Anammox(DAMO-Anammox)工艺在城市主流工况的应用进展;详细探讨了主流Anammox工艺面临低温、进水负荷不均和光照等环境因素冲击时,可施行的“侧流污泥补充至主流”“侧流污水间歇性补充至主流”“驯化生物膜颗粒”等内源性以及外源性的强化调控策略及内在机制;最后围绕分子生物学技术、材料科学、数字信息技术和管理政策,对加快Anammox生物脱氮技术的创新发展与推广应用进行了展望。