反硝化聚磷菌及其脱氮除磷机理研究进展

水体富营养化是当前水环境保护工作的重点关注问题,微生物修复富营养化水体具有高效、低耗且不产生二次污染等特点,已经成为富营养化水体生态修复的一种重要方式。近年来,对反硝化聚磷菌的研究及其在污水处理工艺中的应用越来越广泛。不同于传统的反硝化细菌联合聚磷菌去除氮磷工艺,反硝化聚磷菌在交替厌氧、缺氧/好氧条件下能同时进行脱氮除磷而被广泛关注与研究。值得注意的是,近几年报道的部分微生物仅在好氧条件下就可进行同时脱氮除磷,但是其脱氮除磷机理仍未理清。基于此,文中总结了目前发现的反硝化聚磷菌和同时硝化反硝化聚磷微生物的种类及特点,并对其脱氮与除磷的关系及其机理进行了系统性分析,对目前反硝化除磷存在的问题进行了梳理,最后对今后的研究方向进行了展望,以期为完善反硝化聚磷菌的脱氮除磷机理及工艺改进提供参考。     

两株好氧反硝化聚磷菌的筛选、鉴定及水质净化研究

旨在从环境样品中筛选对富营养化水体具有良好脱氮除磷效果的好氧反硝化菌。采集福州某养猪场污水处理池中的水样。通过反硝化细菌培养基培养、BTB培养基平板分离、硝酸盐还原试验和蓝白斑筛选法、异染颗粒以及聚-β-羟基丁酸(PHB)颗粒染色试验,筛选获得两株具有脱氮除磷特性的菌株,命名为N1和N2。经16S r RNA基因序列分析,N1和N2分别属于无色杆菌属(Achromobacter.sp)和短波单胞菌属(Brevundimonas.sp)。将菌株N1和N2复配,获得脱氮除磷复合菌FIM-1。考察了菌株对人工合成污水和富营养化水体脱氮除磷的效果。结果表明,两株菌在含磷量较低的水体中,对磷的去除率较高,相对于单菌,复合菌表现出更佳的脱氮除磷效果。     

亚硝酸盐对污水生物除磷影响的研究进展

亚硝酸盐作为生物硝化和反硝化的中间产物, 存在于污水生物脱氮除磷系统中。对于生物强化除磷工艺亚硝酸盐既是电子受体用于反硝化除磷, 同时又是抑制剂影响生物除磷过程。本文综述了聚磷菌在厌氧、好氧和缺氧环境中的代谢机理, 在此基础上分别从好氧除磷和反硝化除磷两方面介绍了亚硝酸盐对污水生物除磷影响的研究, 同时概述了亚硝酸盐对生物除磷的抑制机理, 并对该领域的研究提出了个人见解。     

好氧反硝化聚磷菌的筛选及菌群构建优化

【背景】近年来,随着海水养殖规模的扩大,养殖产品产生的排泄物与残留的饲料大量积累,导致养殖水域的氮磷元素含量上升,水体富营养化加剧并对环境造成危害。【目的】从红树林人工湿地中筛选出好氧反硝化聚磷菌株并研究各菌株的最佳除氮除磷效率,随后通过响应面法构建菌群,进一步强化菌株去除污染物的能力。【方法】将前期筛选出的5株耐盐异养硝化-好氧反硝化菌通过异染颗粒染色和聚-β-羟基丁酸(poly-β-hydroxybutyricacid,PHB)染色进行好氧反硝化聚磷菌的筛选,通过单因素试验明确各菌株的最佳除氮除磷条件,并利用Design-Expert软件和Box-Benhnken响应面法进行配比试验。【结果】经过筛选获得3株耐盐好氧反硝化聚磷菌,分别为肺无色杆菌(Achromobacter pulmonis) strain E43、氧化木糖无色杆菌(Achromobacterxylosoxidans)strainJ1和食油假单胞菌(Pseudomonasoleovorans)strain F2,发现菌株E43具有聚磷功能,确定了耐盐好氧反硝化聚磷菌群的最优降解投加比例为E43:J1:F2=1:1:...     

反硝化除磷戈登氏菌属的富集及其菌剂制备

【背景】投加微生物菌剂是强化生物处理效能的重要手段,反硝化是污水脱氮除磷的关键步骤,但目前对于反硝化微生物菌剂相关的研究报道较少。【目的】驯化高效反硝化聚磷菌菌剂,并对系统进行生物强化。【方法】采用两阶段法快速富集反硝化聚磷菌,筛选高效脱氮除磷功能菌株NC1-1并进行鉴定,以NC1-1为菌种来源制备干粉菌剂,研究菌剂强化A²SBR系统污水处理效果。【结果】历经36 d后反硝化聚磷菌富集成功,菌株NC1-1经鉴定属于戈登氏菌属,其脱氮除磷率分别为89.46%和91.68%。麦麸、玉米粉配比为85%:15%、NC1-1投菌量为20 mL、发酵液用量20 mL的条件下成功制得干粉菌剂,干粉菌剂最佳投加量为10%的A²SBR系统总磷（total phosphorus,TP）和NO₃^--N去除率比未投加菌剂的A²SBR系统提高12.06%和11.52%。【结论】菌剂NC1-1的投加使A²SBR系统的污染物去除效能进一步提高,研究结果为进一步研究反硝化聚磷菌菌剂提供了...     

异养硝化-好氧反硝化菌脱氮相关酶系及其编码基因的研究进展

水体氮素污染日益严重,如何经济、高效地去除水体氮素已成为研究热点。近年来,研究人员已从不同环境中分离到许多同时具有异养硝化和好氧反硝化功能的菌株,此类菌生长迅速,可在好氧条件下同时实现硝化和反硝化的过程,并可用于脱除有机污染物,是一类应用潜力巨大的脱氮菌。目前,异养硝化-好氧反硝化菌的脱氮途径和机制主要是通过测定氮循环中间产物或终产物、测定相关酶活性、注释部分氮循环相关基因及参考自养硝化菌和缺氧反硝化菌的氮循环途径等进行研究,其完整的氮素转化途径和氮代谢机制还需要进一步明确。总结了目前异养硝化-好养反硝化菌的脱氮相关酶系及其编码基因的研究进展,以期为异养硝化-好氧反硝化菌的理论研究及其在污水脱氮处理上的应用提供参考。     

强化生物除磷系统的功能微生物研究进展

人类活动过程中排放的磷是导致水体富营养化的重要原因之一,因此,采取强化生物除磷(Enhanced biological phosphorus removal,EBPR)技术去除污水中磷,减轻对环境不利影响。由于具有经济、可持续的优点,EBPR系统在污水除磷中得到广泛应用,而体系中微生物群落组成合理、功能完整是EBPR系统高效稳定运行的关键所在。为了深入了解EBPR系统除磷机理和实现高效稳定运行,对系统中微生物群落结构和主要功能微生物进行了大量研究。EBPR系统中除了具有聚磷能力的聚磷菌(Polyphosphate-accumulating organisms,PAOs)外,还包括没有聚磷能力的非聚磷菌(non-PAOs),主要为聚糖菌(Glycogen-accumulating organisms,GAOs)和一些辅助细菌等。目前,发现与聚磷相关的功能微生物种类越来越多,研究最多的PAOs和GAOs分别为Accumulibacter和Defluviicoccus。PAOs和GAOs在不同的环境条件下存在竞争或合作关系,但是PAOs在特定条件下是否能够表现出GAOs的代谢特性这一问题还存在争论。除传统碳源、p H和温度等因素影响生物除磷外,外源污染物(如抗生素和重金属)对EBPR系统中功能微生物也产生影响。为了获得高效PAOs,传统分离方法、蓝白斑筛选法和人工构建工程菌的方法先后得到应用。现代分子生物学技术的发展为EBPR系统中功能微生物研究提供了先进可靠的技术手段,通过高效聚磷菌的构建实现高效除磷是未来提高实际污水中生物除磷效率的一个重要发展方向。     

一株高效聚磷解淀粉芽孢杆菌的分离鉴定及其除磷条件优化

【背景】磷是引起水体富营养化的主要营养物质。生物除磷具有成本低、效率高且适用范围广等特点,成为近年来水处理研究领域的热点。目前虽然有一些聚磷菌被筛选获得,但它们的除磷效率不高,其除磷条件尚需优化。聚磷菌的固定化及回收利用也亟待研究。【目的】分离筛选并鉴定高效聚磷菌株,优化除磷环境条件,研究吸附材料对所筛菌株除磷的影响,为聚磷菌的开发利用提供理论依据。【方法】采用常规细菌分离筛选方法获得高效菌株,通过形态特征观察、生理生化实验和16S rRNA基因序列分析对菌株进行鉴定;结合单因素试验、Box-BehnkenDesign和响应面分析优化除磷条件;通过测定海绵、无纺布和聚氨酯泡沫对聚磷菌的吸附作用评估该材料的固定化效果。【结果】从连云港市某磷矿厂废水中分离筛选出一株高效聚磷细菌P49,经鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens);优化后的最佳除磷条件为pH 6.8、温度31℃、装液量30.2%,在此条件下P49除磷率可达80.43%;应用聚氨酯泡沫的吸附效果优于海绵和无纺布。【结论】解淀粉芽孢杆菌P49具有良好的除磷效果,可为生物除磷提供微生物资源,用聚氨酯泡沫吸附可实现对该菌株的固定化和回收利用。     

传统厌氧/好氧生物除磷与厌氧/缺氧反硝化除磷效能的比较

采用序批式反应器(SBR),对比厌氧/好氧(A/O)和厌氧/缺氧(A/A)2种运行模式对模拟生活和工业混合污水同时脱氮除磷的效能。结果表明:反硝化聚磷菌完全可以在厌氧/缺氧交替运行条件下得到富集,稳定运行的2种模式对有机物和P的去除率分别保持在90%和85%以上,且A/A SBR具有更强的释磷能力,其释磷量比A/O SBR高出1.2倍。进一步试验表明:磷的释放在有无硝酸盐的情况下效果是不同的。2个系统内污泥均有反硝化除磷能力,A/A SBR中所含反硝化聚磷菌(DPAO)的比例是A/O SBR的4.56倍。2种模式出水水质都能取得较好的效果,且能实现同步除磷脱氮,而反硝化除磷在生物除磷方面更具优势。     

好氧反硝化生物脱氮技术的研究进展

好氧反硝化生物脱氮技术自提出以来,凭借能实现同步硝化反硝化、节省基建投资及运行费用等诸多优点,受到国内外环境领域学者的广泛关注。本文首先总结了近年来好氧反硝化菌种的筛选分离情况,以及环境因子对好氧反硝化菌脱氮效能的影响,包括溶解氧(dissolved oxygen,DO)、碳氮比(C/N)、温度等。然后深入探讨了好氧反硝化生物脱氮技术的原理,好氧反硝化过程中的关键功能基因及酶,同时介绍了分子生物技术在好氧反硝化研究过程中的应用,以及好氧反硝化生物脱氮技术在实际应用方面的研究现状。最后,基于目前的研究瓶颈问题,对未来好氧反硝化生物脱氮技术的研究方向提出了科学展望。     

聚磷菌JPA1菌株的生长特性和聚磷条件的优化

以YG培养基为基础,考察不同条件对聚磷菌JPA1菌株生长及聚磷效率的影响.结果表明:JPA1菌株生长的对数期为3～9h,9h后进入稳定期,12 h到达衰亡期.在单因素试验中,麦芽糖为JPA1菌株最适生长和聚磷的C源,最适生长温度为30～ 35℃,pH为8,Na+、Ca2+、Mg2-、Mn2+和K+等离子有利于JPA1菌株的生长;最适聚磷温度为30 ～ 35℃,pH为7,Fe2+、Na+、Mg2+、Mn2+和K+等离子有利于JPA1菌株的聚磷.正交试验结果表明:JPA1菌株去磷培养基的最优组合为麦芽糖1.5 g/L,温度37℃,pH 6.5,装液量50 mL(300 mL摇瓶);菌株最适扩增培养基为麦芽糖1.5 g/L,温度37℃,pH 6.5或7.5,装液量150 mL(300 mL摇瓶).     

聚磷茵JPA1菌株的生长特性和聚磷条件的优化

以YG培养基为基础,考察不同条件对聚磷菌JPA1菌株生长及聚磷效率的影响。结果表明：JPA1菌株生长的对数期为3-9h,9h后进入稳定期,12h到达衰亡期。在单因素试验中,麦芽糖为JPA1菌株最适生长和聚磷的C源,最适生长温度为30-35℃,pH为8,Na＋、Ca2＋、Mg2＋、Mn2＋和K＋等离子有利于JPA1菌株的生长;最适聚磷温度为30-35℃,pH为7,Fe2＋、Na2＋、Mg2＋、Mn“和K＋等离子有利于JPA1菌株的聚磷。正交试验结果表明：JPA1菌株去磷培养基的最优组合为麦芽糖1．5g／L,温度37℃,pH6．5,装液量50mL（300mL摇瓶）;菌株最适扩增培养基为麦芽糖1．5g/L,温度37℃,pH6．5或7．5,装液量150mL（300mL摇瓶）。     

Impact of nitrite on aerobic phosphorus uptake by poly-phosphate accumulating organisms in enhanced biological phosphorus removal sludges

Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5 % of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10^?3 mg HNO₂-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10^?3 mg HNO₂-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10^?3 and 2.13 × 10^?3 mg HNO₂-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite.     

Free nitrous acid inhibition on anoxic phosphorus uptake and denitrification by poly-phosphate accumulating organisms

Nitrite has been found in previous research an inhibitor on anoxic phosphorus uptake in enhanced biological phosphorus removal systems (EBPR). However, the inhibiting nitrite concentration reported varied in a large range. This study investigates the nitrite inhibition on anoxic phosphorus uptake by using four different mixed cultures performing EBPR with pH considered an important factor. The results showed that the protonated species of nitrite, HNO(2) (or free nitrous acid, FNA), rather than nitrite, is likely the actual inhibitor on the anoxic phosphorus uptake, as revealed by the much stronger correlation of the phosphorus uptake rate with the FNA than with the nitrite concentration. All the four EBPR sludges showed decreased anoxic phosphorus uptake rates with increased FNA concentrations in the studied range of 0.002-0.02 mg HNO(2)-N/L. The phosphorus uptake by all four cultures was completely inhibited at 0.02 mg HNO(2)-N/L. Granular sludge appeared to be more tolerant to HNO(2) than flocular sludge likely due to its stronger resistance to the transfer of nitrite into the bacterial aggregates. Furthermore, denitrification by the phosphorus-accumulating organisms (PAOs) was also found to be inhibited by HNO(2). The denitrification rate decreased by approximately 40% when the FNA concentration was increased from 0.002 to 0.02 mg HNO(2)-N/L.     

两株高效聚磷菌的筛选及其聚磷特性的研究

采用梯度驯化及平板分离技术,从巢湖底泥中筛选到两株高效聚磷菌,分别命名为P6与P8。经过厌氧和好氧两个阶段的处理,两种菌株的聚磷率均达到80%以上。实验结果表明,P8菌株在10℃-40℃以及pH值4-11的较宽范围内都显示出稳定的聚磷效果,而P6菌株仅在30℃-35℃以及pH值4-5的狭窄范围内达到较高的聚磷率。不同碳氮源的影响实验表明,除了乳糖以外,P8菌株在所考察的多种碳氮源下都能表现出较高的聚磷率,当乙醇浓度为3.75g/L时,聚磷率可达到92.9%;而P6菌株对碳氮源则有较严格的要求。     

Competition between polyphosphate and glycogen accumulating organisms in enhanced biological phosphorus removal systems with acetate and propionate as carbon sources

Enhanced biological phosphorus removal (EBPR) is a widely used process for achieving phosphorus removal from wastewater. A potential reason for EBPR failure is the undesirable growth of glycogen accumulating organisms (GAOs), which can compete for carbon sources with the bacterial group responsible for phosphorus removal from wastewater: the polyphosphate accumulating organisms (PAOs). This study investigates the impact of carbon source on EBPR performance and the competition between PAOs and GAOs. Two sequencing batch reactors (SBRs) were operated during a 4-6 month period and fed with a media containing acetate or propionate, respectively, as the sole carbon source. It was found that the acetate fed SBR rarely achieved a high level of phosphorus removal, and that a large portion of the microbial community was comprised of "Candidatus Competibacter phosphatis", a known GAO. The propionate fed SBR, however, achieved stable phosphorus removal throughout the study, apart from one brief disturbance. The bacterial community of the propionate fed SBR was dominated by "Candidatus Accumulibacter phosphatis", a known PAO, and did not contain Competibacter. In a separate experiment, another SBR was seeded with a mixture of PAOs and a group of alphaproteobacterial GAOs, both enriched with propionate as the sole carbon source. Stable EBPR was achieved and the PAO population increased while the GAOs appeared to be out-competed. The results of this paper suggest that propionate may provide PAOs with a selective advantage over GAOs in the PAO-GAO competition, particularly through the minimisation of Competibacter. Propionate may be a more suitable substrate than acetate for enhancing phosphorus removal in EBPR systems.     

Comparison of acetate and propionate uptake by polyphosphate accumulating organisms and glycogen accumulating organisms

Enhanced biological phosphorus removal (EBPR) performance is directly affected by the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigates the effects of carbon source on PAO and GAO metabolism. Enriched PAO and GAO cultures were tested with the two most commonly found volatile fatty acids (VFAs) in wastewater systems, acetate and propionate. Four sequencing batch reactors (SBRs) were operated under similar conditions and influent compositions with either acetate or propionate as the sole carbon source. The stimulus for selection of the PAO and GAO phenotypes was provided only through variation of the phosphorus concentration in the feed. The abundance of PAOs and GAOs was quantified using fluorescence in situ hybridisation (FISH). In the acetate fed PAO and GAO reactors, "Candidatus Accumulibacter phosphatis" (a known PAO) and "Candidatus Competibacter phosphatis" (a known GAO) were present in abundance. A novel GAO, likely belonging to the group of Alphaproteobacteria, was found to dominate the propionate fed GAO reactor. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to take up acetate and propionate. PAOs enriched with acetate as the sole carbon source were immediately able to take up propionate, likely at a similar rate as acetate. However, an enrichment of GAOs with acetate as the sole carbon source took up propionate at a much slower rate (only about 5% of the rate of acetate uptake on a COD basis) during a short-term switch in carbon source. A GAO enrichment with propionate as the sole carbon source took up acetate at a rate that was less than half of the propionate uptake rate on a COD basis. These results, along with literature reports showing that PAOs fed with propionate (also dominated by Accumulibacter) can immediately switch to acetate, suggesting that PAOs are more adaptable to changes in carbon source as compared to GAOs. This study suggests that the PAO and GAO competition could be influenced in favour of PAOs through the provision of propionate in the feed or even by regularly switching the dominant VFA species in the wastewater. Further study is necessary in order to provide greater support for these hypotheses.     

Monitoring accumulating data in a clinical trial

A clinical trial is monitored for efficacy or safety; the variable of interest is death or a similarly serious event. The probability that one therapy has a greater mortality rate than the other is calculated ad libitum during the trial. Adjustments are made for differing patients' prognoses and for survival times.