短程反硝化除磷系统的驯化及除磷特性研究

依据反硝化除磷(DBP)原理,采用批式试验,以城市污水为处理对象,研究了以NO_2~-为电子受体的反硝化除磷菌的筛选与富集,并对其反硝化除磷性能进行了考察.结果表明:NO_2~-对传统EBPR系统的抑制作用明显高于以NO_3~-为电子受体的反硝化除磷系统;对以NO_3~-为电子受体的反硝化除磷污泥用NO_2~-进行驯化,经过52个周期,缺氧吸磷量由0.3 mg/L升高到9.1mg/L,短程反硝化除磷系统驯化成熟;驯化成熟的短程反硝化除磷系统仍能以氧和NO_3~-作为电子受体进行吸磷并维持较高的吸磷速率,以亚硝酸盐为电子受体的除磷菌占总除磷菌的58.82%,说明短程反硝化除磷菌存在于传统除磷系统中,且能够很好地利用氧和硝酸盐为电子受体进行反硝化除磷.     

缺氧区、好氧区容积比对A2/O工艺反硝化除磷的影响

反硝化除磷菌可以在碳源不足的条件下,通过"一碳两用"的方式同时实现反硝化脱氮和吸磷过程,有研究表明,A2/O工艺中存在反硝化除磷现象.为此以啤酒废水为处理对象,研究了缺氧区与好氧区容积比对A2/O工艺反硝化除磷的影响.试验结果表明,在缺氧区与好氧区容积比分别为0.33、0.48、0.60的条件下,A2/O系统对总氮的平均去除率分别为68.04%、79.64%和85.70%,对总磷的平均去除率分别为85.38%、90.80%和96.84%,对COD的去除率均在90%以上.此外,如果继续增大缺氧区与好氧区容积比,应适当调整内循环比,否则会由于缺氧区硝酸盐浓度不够而发生二次释磷现象.     

反硝化除磷的生物化学代谢模型

基于Delft科技大学和活性污泥法动力学模型（ASM2D）推出的反硝化除磷生物化学代谢模型，从生物除磷的计量学和动力学两方面介绍了反硝化除磷过程一系列复杂的生化反应机理。反硝化除磷与传统好氧除磷的生化反应机理非常相似，两种除磷模式的许多化学计量学和动力学方程可以通用；好氧除磷动力学所涉及的一部分参数同时也适用于反硝化除磷动力学；两者最大的区别就是氧化单位NADH2所吸收的磷酸盐量（P／NADH2）不同。引起两者P／NADH2值不同的最根本原因在于：以氧气作为电子受体和以硝态氮作为电子受体，消耗单位NADH2所产生的ATP量不同。在An／ASBR反硝化除磷系统中，测得该值为1．0molATP／molNADH2，此值较An／OS-BR型好氧吸磷系统降低了40％左右。     

反硝化聚磷污泥的培养驯化及关键参数研究

反硝化聚磷污泥的培养是反硝化除磷工艺运行的前提.采用厌氧/好氧诱导富集以PAOs、厌氧/缺氧诱导富集DPB、厌氧/缺氧连续流强化DPB的三阶段方式培养反硝化聚磷污泥,并考察了其关健参数.结果表明,采用该培养方式可成功培养出反硝化聚磷污泥;C/P是PAOs富集阶段的关键参数,其值宜控制在15-20;对于DPB的富集,C/N是关键参数,C/N为2-4时培养效果较好;而在连续流厌氧强化阶段,除C/N外,污泥回流比亦为关键参数,建议该阶段的污泥回流比取0.35-0.5.     

反硝化除磷菌驯化培养方式研究

根据反硝化除磷技术的特点,详细介绍了反硝化除磷菌驯化培养方式的两种不同类型,并对两种方式分别培养反硝化除磷污泥的结果进行了分析,以期获得较快的反硝化除磷污泥培养方式。     

Denitrifying phosphorus removal: linking the process performance with the microbial community structure

This study investigated the link between the process performance of two denitrifying phosphorus (P) removal systems and their microbial community structure. Two sequencing batch reactors (SBRs) were operated with either acetate or propionate as the sole carbon source, and were gradually acclimatised from anaerobic-aerobic to anaerobic-anoxic conditions. It was found that the propionate SBR was able to sustain denitrifying P removal after acclimatisation, while the enhanced biological phosphorus removal (EBPR) activity in the acetate reactor collapsed after the aerobic phase was eliminated. The results suggested that the anoxic glycogen production rate in the acetate SBR was insufficient to support the anaerobic glycogen demand for acetate uptake. The chemical transformations in each SBR suggested that different types of polyphosphate-accumulating organisms (PAOs) were present in each system, possessing different affinities for nitrate. Microbial characterisation with fluorescence in situ hybridisation (FISH) revealed that Accumulibacter was the dominant organism in each reactor, although different cell morphotypes were observed. A coccus morphotype was predominant in the acetate SBR while the propionate SBR was enriched in a rod morphotype. It is hypothesised that the coccus morphotype corresponds to an Accumulibacter strain that is unable to use nitrate as electron acceptor but is able to use oxygen, and possibly nitrite. The rod morphotype is proposed to be a PAO able to use nitrate, nitrite and oxygen. This hypothesis is in agreement with literature studies focussed on the identity of denitrifying PAOs (DPAOs), as well as a recent metagenomic study on Accumulibacter.     

以亚硝酸盐为电子受体的反硝化除磷工艺的启动

采用两阶段培养驯化的方式快速启动以亚硝酸盐为电子受体的反硝化除磷系统,第一阶段通过厌氧/好氧交替运行方式富集聚磷菌,第二阶段采用厌氧/缺氧交替运行方式逐渐筛选以亚硝酸盐为电子受体的反硝化聚磷菌。经过约120 d的运行,成功实现了系统的快速启动,且稳定后的系统具有良好的反硝化除磷能力,平均出水总氮和总磷分别为5.39、1.55 mg/L,平均去除率分别达到82.5%、80.0%。     

温度对A/O工艺反硝化除磷效果的影响

以A／O工艺中充分释磷的厌氧污泥为研究对象,分别投加NO3^- -N和NO2^- -N,考察了温度对反硝化除磷效果的影响。结果表明,在一定范围内,随着温度的升高,NO3^- -N型反硝化除磷和脱氮速率均加快,但消耗单位氮的吸磷量却下降,若要取得良好的氮、磷去除效果,需适当提高缺氧段的NO3^- -N浓度;NO2^- -N对聚磷菌的抑制浓度并非为定值,而是随温度的升高而上升;随温度的升高,NO2^- -N型反硝化脱氮速率加快,而吸磷速率却未表现出明显的上升趋势。     

Simultaneous nitrogen and phosphate removal in aerobic granular sludge reactors operated at different temperatures

The main biological conversions taking place in two lab-scale aerobic granular sludge sequencing batch reactors were evaluated. Reactors were operated at different temperatures (20 and 30 °C) and accomplished simultaneous COD, nitrogen and phosphate removal. Nitrogen and phosphate conversions were linked to the microbial community structure as assessed by fluorescent in situ hybridization (FISH) analysis. Anoxic tests were performed to evaluate the contribution of anoxic phosphate uptake to the overall phosphate removal and to clarify the denitrification pathway. Complete nitrification/denitrification and phosphate removal were achieved in both systems. A considerable fraction of the phosphate removal was coupled to denitrification (denitrifying dephosphatation). From the results obtained in anoxic batch experiments dosing either nitrite or nitrate, denitrification was proposed to proceed mainly via the nitrate pathway. Denitrifying glycogen-accumulating organisms (DGAOs) were observed to be the main organisms responsible for the reduction of nitrate to nitrite. A significant fraction of the nitrite was further reduced to nitrogen gas while being used as electron acceptor by denitrifying polyphosphate-accumulating organisms (PAO clade II) for anoxic phosphate uptake.     

(AO)2-SBBR反硝化除磷工艺处理低碳城市污水

低碳源浓度城市污水的脱氮除磷一直是个难题，为此在AO-SBBR工艺中引入一个缺氧段而形成（AO）2-SBBR工艺，研究了AO-SBBR和（AO）2-SBBR对低碳源浓度城市污水中氮、磷的去除效果。试验结果表明：在进水BOD5／TN=3、BOD5／TP=17的情况下，（AO）2-SB．BR工艺比AO-SBBR工艺具有更好的同步脱氮除磷效果，对总磷的去除率达到了79．8％，对总氮的去除率从25．83％提高到51．26％，出水水质达到了《城镇污水处理厂污染物排放标准》的一级标准。该工艺有效解决了低碳源浓度城市污水在同步脱氮除磷过程中有机物不足的问题，并在单一反应器中实现了反硝化除磷菌的增殖过程，反硝化除磷菌占聚磷菌的比例从14．82％增长到63．04％；反硝化除磷菌能够以低浓度的亚硝酸盐氮作为电子受体进行缺氧吸磷，如亚硝酸盐氮〉10mg／L则会抑制反硝化除磷菌的活性，而且这种抑制作用并不是瞬时的，至少要持续一段时间其活性才能恢复。     

Kinetic competition between phosphorus release and denitrification on sludge under anoxic condition

The kinetic behaviors of simultaneous phosphorus release and denitrification on sludge were investigated under anoxic condition. A phosphorus enriched sludge produced from Anaerobic-Anoxic-Oxic (AnAO) process under various SRT (5, 10 and 15 days) operation conditions was carried out in a series of batch tests. Experimental results indicated that the available organic substrate determined the kinetic behaviors of phosphorus release/uptake and denitrification. The simultaneous phosphorus release and denitrification demonstrated a kinetic competition under anoxic conditions in the presence of an available organic substrate. When the substrate was abundant, sludge was under “releasable-phosphorus-limited” condition; phosphorus release rate decreased slightly by nitrate inhibition. However, nitrate significantly inhibited phosphorus release when sludge was under “initial-substrate-limited” condition. Moreover, the sludge's phosphorus contents (as created by different SRT processes) dominated the kinetics of competition between phosphorus release and denitrification. The sludge with a high phosphorus content had a higher phosphorus release rate in accordance with a lower denitrification rate. Additionally, the substrate sequestrated rate markedly increased under the condition of simultaneous phosphorus release and denitrification. Finally, a preliminary metabolism model of denitrifying phosphorus removal bacteria was proposed, and found to be capable of adequately accounting for simultaneous phosphorus release and denitrification under anoxic conditions.     

缺氧区、好氧区容积比对A^2／O工艺反硝化除磷的影响

反硝化除磷茵可以在碳源不足的条件下，通过“一碳两用”的方式同时实现反硝化脱氮和吸磷过程，有研究表明，A^2／O工艺中存在反硝化除磷现象。为此以啤酒废水为处理对象，研究了缺氧区与好氧区容积比对A^2／O工艺反硝化除磷的影响。试验结果表明，在缺氧区与好氧区容积比分别为0．33、0．48、0．60的条件下，A^2／O系统对总氮的平均去除率分别为68．04％、79．64％和85．70％，对总磷的平均去除率分别为85．38％、90．80％和96．84％，对COD的去除率均在90％以上。此外，如果继续增大缺氧区与好氧区容积比，应适当调整内循环比，否则会由于缺氧区硝酸盐浓度不够而发生二次释磷现象。     

低碳源、低能耗型改良A2/O工艺的脱氮除磷研究

介绍了一种新型的脱氯除磷工艺及其运行情况。该工艺是对传统A^2／O工艺的改进（可称为改良型A^2／O工艺），它采用了后置反硝化系统以及厌氧池碳源分流技术和回流污泥预缺氧反硝化技术，以提高系统的脱氯除磷效果。研究结果表明：在进水COD≥300mg／L，TN为40．3mg／L，TP为3．82mg／L时，对TN、TP及COD的去除率分别可迭70％、86％和88％；当COD〈300mg／L时，对TP的去除效果较差，但对TN和COD的去除率仍分别可达60％和85％；试验期间，污泥沉降性能良好。     

污泥回流比对A_2N反硝化除磷工艺脱氮除磷的影响

以城市生活污水为研究对象,探讨了不同的超越污泥和回流污泥回流比对A2N工艺脱氮除磷的影响.在超越污泥回流比与回流污泥回流比相同且分别为0.3、0.4和0.6的条件下,A2N工艺对COD的平均去除率分别为92.5%、90.3%、91.6%,相应的出水COD为20.3、28.4、25.3 mg/L;对总氮的平均去除率分别为87.1%、90%、84.9%,出水总氮分别为6.75、5.43、6.95mg/L;对磷的平均去除率分别为99.5%、99.6%和99.0%,出水磷浓度分别为0.02、0.02、0.05mg/L.当回流比为0.4时,A2N系统的除污效果最好.研究还发现,超越污泥流量直接决定了未经硝化而直接进入缺氧池的氨氮量,进而影响出水氨氮浓度.因此,在保证缺氧池有足够污泥的前提下,应尽可能减小超越污泥流量,以降低出水氨氮浓度.     

Characterization of denitrifying phosphate-accumulating organisms cultivated under different electron acceptor conditions using polymerase chain reaction-denaturing gradient gel electrophoresis assay

To investigate the characteristics and the microbial diversity of denitrifying phosphate-accumulating organisms (DNPAOs) that are capable of conducting enhanced biological phosphorus removal (EBPR) using nitrate as electron acceptor, three sequencing batch reactors were operated under three different electron acceptor conditions, i.e., only oxygen, oxygen together with nitrate and only nitrate. Based on the chemical analysis concerning the biochemical transformation of each reactor, it was found that phosphate-accumulating organisms responsible for EBPR consisted of at least three populations including DNPAOs, and that the microbial community structure was changed according to the electron acceptor conditions. Also, the sludge cultivated with oxygen together with nitrate showed a drastic increase in the amount of phosphorus uptake under anoxic conditions, which suggested that a proportion of DNPAOs capable of utilizing nitrate under aerobic conditions were present. On the other hand, the change in microbial community structure depending on the type of electron acceptor was demonstrated by the analysis of the results of denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal DNA fragments. It was found that the bacteria commonly contained in all the reactors were Rhodocyclus sp. (96% identity) and Dechlorimonas sp. (97% identity) that belonged to the beta subclass of Proteobacteria on the basis of the analysis of the sequence excised from DGGE bands and the determination of phylogenetic affiliation. However, only the presence of Rhodocyclus sp. in all the reactors was demonstrated by fluorescent in situ hybridization analysis.     

溶解氧对反硝化聚磷菌的影响研究

为考察在有氧条件下好氧聚磷菌与反硝化聚磷菌（DPB）可否共存,以模拟低碳城市污水为原水,在厌氧／缺氧运行的SBR内引入不同时长的好氧段以及在厌氧／好氧运行的SBR内采用相同时长的好氧段和不同的溶解氧浓度,考察了DO对DPB的存活及其除磷脱氮功能的影响。结果表明,聚磷菌（PAOs）以氧或硝酸盐氮为电子受体时的吸磷能力基本相同,且其在缺氧和好氧条件下的活性也基本相同;在有氧条件下,维持低氧环境有利于DPB反硝化除磷的实现,而高DO浓度则利于好氧吸磷。因此,DO对DPB的存活没有决定性影响,DPB和好氧PAOs可以共存,而对DO浓度的合理控制是实现反硝化除磷的关键。     

同时硝化/反硝化除磷过程的控制策略研究

为实现同时硝化/反硝化除磷(SNDPR)过程,在SBR反应器内,采用模拟低碳源污水和厌氧-交替好氧/缺氧的运行方式对污泥进行培养驯化,成功实现了反硝化聚磷茵和硝化茵的良好共存.在此基础上,考察了厌氧/间歇曝气和厌氧/连续曝气两种模式下SNDPR工艺对污水的处理效果.结果表明,在上述两种模式下,系统对TP的去除率分别为92%和90%,对TN的去除率分别为83%和72%;厌氧/间歇曝气模式更有利于SNDPR工艺对低碳源污水的处理.另外,对电化学参数的研究表明,pH曲线上的"膝点"可近似预示SNDPR过程的结束,而ORP的变化范围及稳定性可预示SNDPR过程中硝化和反硝化除磷同时发生的平衡程度.     

混合液及污泥回流比对MUCT工艺缺氧吸磷的影响

以C/N值较低的模拟生活污水为处理对象,研究了当硝化液回流比保持不变时,混合液回流比(r)和污泥回流比(s)对MUCT工艺缺氧吸磷的影响.结果表明:当r和s均为1时,缺氧区2和缺氧区3中的DPB利用厌氧段储存的大量PHB为碳源,以硝酸盐氮为电子受体进行吸磷,吸磷量分别稳定在132.91 mg/h和105.38 mg/h左右,缺氧吸磷率维持在46.58%左右;r和s对COD总去除率的影响不大,系统对COD、NH+4 -N、TP的去除率分别达到91.86%、98.83%和90%,出水COD、NH+4-N和11P分别在30、0.8和0.9 mg/L以下.     

Phosphorus and nitrogen removal with minimal COD requirement by integration of denitrifying dephosphatation and nitrification in a two-sludge system

Denitrifying dephosphatation enables the removal of phosphorus and nitrogen with minimal use of COD, minimal oxygen consumption and minimal surplus sludge production. Moreover it would make aeration only necessary for nitrification. Therefore we have studied an anaerobic-anoxic (A₂) sequencing batch reactor (SBR) coupled to a nitrification SBR. Denitrifying phosphorus removing bacteria (DPB) and nitrifiers were completely separated in two sludges in these two SBRs. The nitrified supernatant was recirculated from the nitrification SBR to the A₂ SBR where nitrate was utilized by DPB as an electron acceptor for phosphorus removal. The technical feasibility for simultaneous phosphorus and nitrogen removal in the proposed two-sludge system was evaluated. The benefits of two-sludge systems over single-sludge systems were also discussed. It could be concluded that the separation of the nitrification step leads to an optimal process design for the application of denitrifying dephosphatation. The two-sludge system showed stable phosphorus and nitrogen removal, and enabled the removal of 15 mg-P/1 and 105 mg N/1 at the expense of only 400 mg-COD/1 acetic acid. Stoichiometric calculations showed that, in the two-sludge system the required COD can be up to 50% less than for conventional aerobic phosphorus and nitrogen removal systems. Moreover oxygen requirements and sludge production can be decreased in significant amounts of about 30 and 50%, respectively.     

短好氧泥龄下A2/O和BAF联合工艺的脱氮除磷特性

采用小试装置,研究了短好氧污泥龄下A2/O和BAF联合工艺处理低C/N和C/P污水时的脱氮除磷特性.结果表明,通过提高A2/O工艺段的厌氧区有机负荷和缺氧区硝酸盐负荷对反硝化聚磷菌（DPAOs）进行选择和强化后,其在聚磷菌（PAOs）中的比例维持在28%左右,工艺具有部分反硝化除磷能力,能够减少脱氮除磷过程中对碳源的总需求量.但在联合工艺中,好氧除磷仍是主要的除磷方式.在A2/O工艺段内,好氧污泥龄在满足好氧PAOs存活的同时,还必须满足抑制硝化细菌生长的要求,且为了保证工艺对磷的整体去除效果,混合液在好氧区的接触时间须大于30 min.此外,以保证缺氧区出水中含有1～4 mg/L的硝态氮为原则来控制BAF出水的回流量,可达到较好的脱氮除磷效果.该联合工艺结合了活性污泥工艺和生物膜工艺的优点,运行稳定,出水水质优良,不仅适合于新建污水处理厂,也特别适合于不能脱氮除磷污水处理厂的技术改造.