聚磷菌以乙酸为基质的厌氧生化机理研究进展

阐述了厌氧条件下聚磷菌以乙酸为基质的生物化学特性,从多聚磷酸盐代谢、乙酸的转运及转化途径、质子移动力产生途径、胞内pH调节机制、聚羟基烷酸代谢、糖原代谢等六个方面展开论述,并对今后的研究重点进行了展望。     

亚硝酸盐氮浓度对厌氧氨氧化反应的影响

以生物膜滤池为厌氧氨氧化反应器，考察了进水中的亚硝酸盐氮浓度对总氮去除率的影响。结果显示，亚硝酸盐氮浓度对总氮去除率的影响较大，总氮去除率和pH值的变化幅度均随NO2^--N浓度的增加而增大；但NO2^--N浓度升高到一定程度时，若再进一步提高其浓度则对TN的去除率将随之下降，pH值的变化幅度也随之减小，高浓度NO2^--N会对厌氧氨氧化反应产生抑制作用。     

不同温度及厌氧/好氧运行条件对聚磷菌衰减特性的影响

以富含90%±2%纯度聚磷菌（PAOs）的强化生物除磷系统（EBPR）为研究对象,考察了10℃厌氧、10℃好氧、20℃厌氧、20℃好氧4种运行条件下PAOs的衰减特征。结果表明：温度越高对应衰减速率越快,4个系统在1~9 d里衰减速率的平均值分别为：10℃厌氧：0.053/d;10℃好氧：0.050/d;20℃厌氧：0.072/d;20℃好氧：0.145/d。其中4个系统由于细胞死亡引起的活性衰减速率分别为：10℃厌氧：0.019/d;10℃好氧：0.017/d;20℃厌氧：0.019/d;20℃好氧：0.03/d,占总活性衰减的比例分别为：35.8%、34%、26.4%、20.7%。在9 d饥饿衰减期间,污泥中所含PHA与糖原的量总体呈下降趋势。相同温度下,糖原在厌氧衰减过程中降解速率大于好氧;在同样的厌氧、好氧衰减条件下,温度越高糖原降解速率越快。     

生物除磷系统中聚磷菌与聚糖菌代谢模型比较

基于国内外学者对生物除磷代谢机理的最新研究成果，介绍了生物除磷系统中聚磷菌与聚糖菌的代谢模型，并对两者进行了比较。指出有必要对聚磷菌与聚糖菌的代谢机理与生理特性进行进一步研究，以提高系统的运行效率和稳定性。     

聚磷菌的诱导驯化与分离

采用A/O方式运行的SBR反应器对回流污泥进行诱导驯化,结果表明在较短时间内系统有明显的聚磷特征,A/O方式运行的反应器除磷效率大于95%,从运行稳定的系统中进行微生物的分离,经过数次分离得到纯种的菌株,通过染色试验表明,菌体内含有异染颗粒.     

以Fe(Ⅲ)为电子受体的聚磷菌筛选、鉴定及聚磷特性

结合平板分离法、poly-P和PHB染色以及柠檬酸铁还原实验,从污水处理厂活性污泥中分离获得一株以Fe(Ⅲ)为电子受体厌氧聚磷的聚磷菌株AP3, 其16S rDNA与Pseudomonas mosselii ATCCBAA-99的同源性为99%。菌株AP3于柠檬酸铁液体培养基和无铁液体培养基中厌氧避光、27 ℃静置培养,在含有Fe(Ⅲ)的培养基中比在无Fe(Ⅲ)的培养基中生长好;菌株AP3在无Fe(Ⅲ)的培养基中,表现出典型的厌氧释磷特征,释磷量为3.68 mg·L-1;在含有Fe(Ⅲ)的培养基中,先厌氧释磷,释磷量为6.62 mg·L-1, 10 h之后开始厌氧聚磷,聚磷量为5.89 mg·L-1。菌株AP3能以Fe(Ⅲ)为电子受体,具有厌氧聚磷特征。     

聚磷菌PAO1-1的筛选及除磷特性

从运行稳定的以生活污水为碳源的生物除磷污泥中筛选出一株聚磷菌PAO1-1,该菌株对普通活性污泥系统具有很好的强化作用,驯化10 d后可使除磷率由投菌前的44%提高到90%以上。对该菌株的形态、生理生化特征及16S rDNA序列进行分析后,鉴定该菌株为产碱杆菌属。该菌株对磷的平均吸收速率为13.8 mg/(g.h),处于“磷酸盐饥饿期”时对磷的吸收速率为19.2 mg/(g.h),比“非饥饿期”提高了39.1%。处于对数期的PAO1-1在厌氧条件下的无磷培养基中的释磷速率为11.8 mg/(g.h),稳定期释磷速率为7.0 mg/(g.h),释磷速率下降了40.7%。     

SBR生物除磷系统中聚磷菌的特性研究

采用人工合成污水,在两个分别以厌氧／好氧（A／O）和厌氧／缺氧（A／A）运行的SBR反应器中进行生物除磷诱导与强化,并对聚磷菌（PAOs）的特性进行了研究。采用传统分离方法从这两个运行稳定且可高效除磷的SBR反应器中获得了37株纯种菌,经异染颗粒和聚β－羟基丁酸（PHB）颗粒染色及纯种培养后,确定其中7株为高效聚磷菌。通过生理生化特性试验,确定SYO－1、SYA－2、SYA－5和FCO－2为假单胞菌属（Pseudomonas）,SYO－2为棒杆菌属（Coryne—bacterium）,SYO－8为肠杆菌科（Enterobacter）,FCO－12为葡萄球菌属（Staphylococcus）。其中SYO－1、SYO－2、SYO－8、FCO－2、FCO－12为传统好氧聚磷菌,SYA－2和SYA－5为反硝化聚磷菌（DNPAOs）。以A／O方式运行的SBR反应器中细菌多样性和聚磷菌种类都较以A／A方式运行的SBR的多。在以A／A方式运行的SBR系统中,反硝化聚磷菌主要为假单胞菌属;而在以A／O方式运行的SBR系统中,除假单胞菌属外,还存在棒杆菌属、肠杆菌科和葡萄球菌属。     

厌氧消化过程中甲烷菌的无机营养需要

人们通常认为,废水中除N、P外含有足够的徽量元素供微生物生长需要。事实并非如此,一些工业废水常常缺乏甲烷菌必要的N、P以外的无机营养元素,即使对城市污水、污泥的研究证明,由于缺乏Fe元素而限制了甲烷菌的活性。近年来研究成果表明,甲烷菌对S的需要量远比通常认为的要多,大体上与N的需要相当;Ni、Co、Fe也是甲烷菌必要的元机营养元素。     

厌氧氨氧化工艺处理低氨氮污水的影响因素研究

考察了厌氧氨氧化（ANAMMOX）工艺处理低氨氮污水的影响因素。结果表明,当进水NO2^--N浓度较低时,提高NO2^--N浓度可促进ANAMMOX反应的进行,而当NO2^-N浓度过高时（〉118．4mg／L）则会对该反应产生抑制作用,但此时ANAMMOX反应并没有停止,厌氧氨氧化菌仍保持较高的活性;适当增加进水的无机碳（IC）浓度可刺激厌氧氨氧化菌的生长,但过高浓度的IC会对厌氧氨氧化菌的生长带来不利影响;进水中总有机碳（TOC）的存在不利于厌氧氨氧化反应的进行;ANAMMOX菌的自养固定CO2过程会导致周边环境呈碱性,为保证反应的顺利进行,应当控制反应器中的pH值。     

硝酸盐浓度对反硝化聚磷菌诱导的影响

通过控制缺氧段硝酸盐浓度,研究了反硝化聚磷菌的诱导方法及效果.批式试验表明,碳源浓度一定时,缺氧段硝酸盐消耗量与聚磷量呈线性关系,且与厌氧释磷量之比等于该线性关系式的斜率.在反硝化聚磷菌诱导过程中,按此比例调整缺氧段的硝酸盐浓度可很快达到良好的脱氮除磷效果,反硝化聚磷率＞95%,反硝化脱氮率＞96%.由同等条件下的缺氧与好氧最大聚磷速率可推知,诱导前反硝化聚磷菌占总聚磷菌的27.61%,诱导后则高达78.61%.     

碳源和进水pH值对聚糖菌代谢的短期影响

通过连续流A/O工艺驯化富集了聚糖菌(GAOs),在此基础上利用静态批次试验分别考察了碳源(乙酸、丙酸和葡萄糖)和进水pH值(6.5、7.0和7.5)对GAOs代谢的短期冲击影响。结果表明,在厌氧阶段,GAOs污泥可以较快的速率吸尽乙酸和丙酸,而葡萄糖仅部分被吸收。对比消耗单位碳源合成的聚-β-羟基烷酸(PHA)量,以葡萄糖为碳源时最大,以丙酸作为碳源时最小。同时,GAOs污泥吸收单位碳源所消耗的糖原量以丙酸最少;而以葡萄糖为碳源时,与乙酸和丙酸情况不同的是其在厌氧反应后期糖原量略有增加。另外,在考察进水pH值对GAOs污泥代谢的短期冲击影响时发现,随着进水pH值的升高,GAOs污泥对挥发性脂肪酸(VFAs)的吸收速率减缓,但进水pH值的短期波动对于胞内物质(糖原、PHA)代谢的影响不大。     

污水强化生物除磷的生化模型研究进展

阐述了在污水强化生物除磷过程中生化模型的建立与发展,重点介绍了与聚磷菌有关的Mino模型,强调了在理解生化模型时应该注意的问题：所有聚磷菌生化模型都只是在试图描述发生在EBPR（Enhanced Biological Phosphorus Removal）生物群中的一些生物化学变化现象和规律（多聚磷酸盐的吸收和水解、PHA的合成与再利用）.另外,还都假设所有具有EBPR能力的细菌都有着共同的代谢特征.所以,尽管这些生化模型有助于对整个EBPR过程的理解,但不应该拘泥于这些生化模型,只有通过对聚磷菌纯培养获得最终成功才能够彻底解决整个问题.     

Effect of nitrite on phosphate uptake by phosphate accumulating organisms

In biological nitrogen removal processes, nitrite can be formed and accumulated through both nitrification and denitrification. Despite the fact that, in practice, biological phosphate removal (BPR) is often combined with biological nitrogen removal, there are only a few publications reporting the effect of nitrite on BPR. In this study, phosphate-accumulating organisms (PAO) were cultivated in an anaerobic-anoxic-aerobic sequencing batch reactor (SBR). The effect of nitrite on the enrichment of the sludge with PAO, the phosphate uptake rates and the sludge respiration was investigated. The results indicate that (1) presence of nitrite inhibits both aerobic and anoxic (denitrifying) phosphate uptake, (2) aerobic phosphate uptake was more affected than anoxic phosphate uptake, (3) presence of nitrite could be one of the factors enhancing the presence of glycogen accumulating organisms (GAO)--competitors to PAO for substrate in the anaerobic phase, and (4) it is required to monitor and control nitrite accumulation in a full-scale wastewater treatment plants.     

微量元素对ABR发酵产氢产甲烷的影响

为构建厌氧折流板反应器(ABR)发酵联合产氢产甲烷系统,考察了微量元素对ABR系统前端格室发酵产氢、后端格室发酵产甲烷的影响。在进水COD为6 000 mg/L、碱度为1 900 mg/L的条件下,当未投加微量元素时,系统对COD的去除率为51%,产氢能力为0.46 m3/(m3.d),产甲烷能力为0.68 m3/(m3.d),四格室的厌氧污泥脱氢酶活性均较低;而在相同运行条件下,当投加微量元素后,系统对COD的去除率提高到62%以上,产氢能力为0.37 m3/(m3.d),产甲烷能力达到1.66 m3/(m3.d)。研究表明,投加微量元素可有效刺激ABR发酵联合产氢产甲烷系统中厌氧污泥的活性,由于ABR中产甲烷菌等耗氢菌群活性的增强导致发酵产氢作用受到抑制,但产甲烷活性的进一步增强,使系统的处理效能得到明显提高。     

不同碳源驯化聚糖菌反硝化及N2O释放特性

为了确定反硝化聚糖菌(DGAOs)的脱氮性能及N₂O释放特性,采用序批式生物反应器,分别以乙酸钠和葡萄糖为碳源(反应器分别记作SBRAc和SBRGl),考察其脱氮过程中的碳源变化以及N₂O释放特性。结果表明,SBRAc和SBRGl的总氮去除率分别为(80.2±2.8)%和(63.4±3.5)%,N₂O产率分别为(7.16±1.43)%和(13.35±2.46)%。以乙酸钠为碳源时,聚糖菌厌氧阶段吸收的有机物主要以胞内聚-β-羟基烷酸(PHA)形式储存;以葡萄糖为碳源时,部分有机物用于胞内糖原(Gly)的积累,PHA合成量减少。聚糖菌内源反硝化过程中,依次利用胞内PHA和Gly作为内碳源,且PHA提供电子的速率远大于Gly,导致SBRGl内NO₂^-大量积累、N₂O释放量增加。NO₂^-对氧化亚氮还原酶活性的抑制效应是导致聚糖菌内源反硝化过程释放N₂O的主要因素。与葡萄糖相比,乙酸钠更易被反硝化聚糖菌吸收为易利用的内碳源PHA,并降低反硝化过程中N₂O的释放量。     

土霉素对厌氧生物处理的抑制作用研究

在35℃、厌氧条件下,通过测定甲烷产量,考察了土霉素对厌氧生物处理的抑制作用。结果表明,土霉素对厌氧生化反应有抑制作用,当土霉素浓度200 mg/L时,会产生中度抑制,对土霉素的去除率65%;当土霉素浓度800 mg/L时,会产生重度抑制。     

Model-based evaluation of competition between polyphosphate- and glycogen-accumulating organisms

Many studies show that glycogen-accumulating non-polyphosphate organisms (GAOs) can compete with polyphosphate-accumulating organisms (PAOs) for organic substrate under anaerobic conditions and may indeed cause the deterioration of enhanced biological phosphorus removal (EBPR) systems. Understanding their behaviors in an anaerobic/aerobic (A/O) system at different operational conditions is essential in developing control strategies that ensure EBPR. A model-based evaluation of competition between PAOs and GAOs under different operational conditions was presented in this study. At 30 degrees C and a 10-day sludge age, the dominance of GAOs in the A/O sequencing batch reactor (SBR) was strongly dependent upon their considerable kinetic advantage in anaerobic acetate uptake. At 20 degrees C and a 10-day sludge age, the kinetic advantage of GAOs in anaerobic acetate uptake could be less, compared to that at 30 degrees C and a 10-day sludge age, leading to the relative dominance of PAOs and a stable phosphorus removal in the A/O system. At 30 degrees C and a 3-day sludge age, the parameters responsible for determining the aerobic distribution of anaerobically stored X(PHA) for both PAOs and GAOs, other than kinetic parameters of anaerobic acetate uptake, are important for them being dominant in the A/O SBR. In a situation when the q(PHA,P) value is lower than q(PHA,G) but comparable, PAOs may still be dominant in the A/O SBR, presumably because their aerobic conversion fraction of biomass production from PHA was higher than that of the GAOs.     

Advancing post-anoxic denitrification for biological nutrient removal

The objective of this research was to advance a fundamental understanding of a unique post-anoxic denitrification process for achieving biological nutrient removal (BNR), with an emphasis on elucidating the impacts of surface oxygen transfer (SOT), variable process loadings, and bioreactor operational conditions on nitrogen and phosphorus removal. Two sequencing batch reactors (SBRs) were operated in an anaerobic/aerobic/anoxic mode for over 250 days and fed real municipal wastewater. One SBR was operated with a headspace open to the atmosphere, while the other had a covered liquid surface to prevent surface oxygen transfer. Process performance was assessed for mixed volatile fatty acid (VFA) and acetate-dominated substrate, as well as daily/seasonal variance in influent phosphorus and ammonia loadings. Results demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L⁻¹ and 0.14 mgP L⁻¹. Observed specific denitrification rates were in excess of typical endogenous values and exhibited a linear dependence on the glycogen concentration in the biomass. Preventing SOT improved nitrogen removal but had little impact on phosphorus removal under normal loading conditions. However, during periods of low influent ammonia, the covered reactor maintained phosphorus removal performance and showed a greater relative abundance of polyphosphate accumulating organisms (PAOs) as evidenced by quantitative real-time PCR (qPCR). While GAOs were detected in both reactors under all operational conditions, BNR performance was not adversely impacted. Finally, secondary phosphorus release during the post-anoxic period was minimal and only occurred if nitrate/nitrite were depleted post-anoxically.