多维度耦合丝状菌监测方法在污泥膨胀中的应用

丝状菌过度生长诱发的活性污泥膨胀是影响城市污水处理厂正常运行的原因之一。活性污泥体积指数(SVI)是判断污泥膨胀过程的关键指标,但无法对膨胀本质——丝状菌的动态变化提供有效信息。在某大型城市污水处理厂完整污泥膨胀及实施膨胀控制策略的过程中,利用多维度耦合丝状菌监测方法对活性污泥性状、丝状菌种群及主要致膨丝状菌动态进行了跟踪监测,结果显示在以SVI划分的不同膨胀阶段,耦合监测方法不仅可以有效定性和定量丝状菌及其种群动态变化,同时对微丝菌(Microthrix parvicella)生长位置及生长状态的准确判定为膨胀整体进程判断及膨胀有效防控提供了直观、准确的微生物信息证据。定量PCR结果显示,耦合监测方法的定量结果不仅与分子生物学精确定量结果的趋势相一致,同时具有相对快速、现场可操作性强、成本低等优势,在我国城市污水处理厂实际污泥膨胀控制中具有重要的应用价值。     

活性污泥中丝状菌与絮体结构的关系研究

通过试验和观察,研究了活性污泥中丝状菌与絮体结构的关系,常见的活性污泥絮体可分为六大类型,在不同的处理工艺和运行条件下,各类型污泥比例不同,丝状菌在污泥絮体的形成过程中所起的作用也不相同。而在活性污泥膨胀时,生物相结构中的丝状菌可分为结构性的和非结构性的两大类,它们起着不同的作用,运行中必须通过不同的方法和措施加以防治。     

A/O除磷工艺丝状菌污泥膨胀的研究

丝状菌污泥膨胀是影响活性污泥法高效、稳定运行的重要因素。采用A/O生物除磷工艺中试装置处理实际生活污水,分析了污泥膨胀发生的原因及恢复系统性能的方法。结果显示,长期曝气不均匀是导致丝状菌污泥膨胀的重要原因,通过调控系统运行参数可以有效控制由低DO值或者高负荷引起的丝状菌污泥膨胀。当发生污泥膨胀后,首先降低负荷至0.45 kgCOD/(kgMLSS.d),调节回流比为83%,同时控制好氧池各段的DO分别为1.5、1.0、1.0 mg/L以淘汰丝状菌,在SVI值降至200 mL/g以下后继续降低回流比至53%,同时降低曝气量以形成1.0、0.5、0.5 mg/L的DO浓度梯度。采取上述调控措施后,SVI值由569.8 mL/g降至150 mL/g以下,污泥性状得以恢复;同时出水COD和TP分别在50、0.5 mg/L以下,去除率分别约为85%、95%。     

活性污泥丝状菌膨胀的运行控制生产性试验研究

某污水处理厂的生物处理单元采用MSBR工艺,在冬季运行期间多次发生丝状菌膨胀现象,对此进行了原因分析和相应的工艺运行调整。首先建立小试系统对不同有机负荷下的活性污泥絮体进行观测,结果表明,当有机负荷为0.12 kgBOD5/(kgMLVSS.d)时,污泥不易发生丝状菌膨胀且沉降性能最好。通过分析MSBR系统的实际运行情况得知,丝状菌膨胀的发生主要是由工艺运行条件改变而引起的,据此对系统的进水流量、有机负荷、污泥龄、曝气量、SBR运行周期等进行调整,最终有效控制了活性污泥丝状菌膨胀。     

不同污泥沉降性能条件下污泥质量浓度对SV与SVI测定值的影响

SV、SVI是评价污泥沉降性能的2个指标[1],一般通常认为SVI值大于150 mL/g,可认为污泥已经发生了膨胀,但实际污泥质量浓度对SV、SVI测定值有一定的影响。研究发现,不同质量浓度的污泥经历30 min沉降后,在发生污泥膨胀之前,SV值基本上都已达到稳定状态,而在发生丝状菌膨胀之后,却恰恰相反。当污泥发生膨胀后,同一时间不同质量浓度下的SVI测定值之间存在差异,而当经历90 min沉降后,同一时间不同质量浓度下的SVI测定值之间的差异已非常小。因此,建议以历时90 min后所测得的污泥SVI值来判断不同质量浓度污泥是否发生膨胀更为准确。     

活性污泥法中引起丝状菌污泥膨胀的因素

活性污泥法是采用最普遍的污水处理工艺,而丝状菌污泥膨胀则是该工艺污水运行中易发生、危害大的问题.介绍了近30 年来国际上关于丝状菌污泥膨胀的最新研究成果,分析了影响丝状菌污泥膨胀的主要因素.     

高浓度消毒剂对活性污泥系统中微生物的影响

针对污水厂活性污泥易于发生丝状菌污泥膨胀问题,以西安市第二污水处理厂活性污泥为研究对象,在次氯酸钠投加量为15 mg/L的条件下,探索高浓度消毒剂对活性污泥中微生物的杀灭效果以及对胞外聚合物(EPS)含量和不同类型微生物活性的影响。结果表明,高浓度次氯酸钠能有效杀灭丝状菌,从而控制污泥的丝状膨胀现象,但在杀灭丝状菌的同时也会影响菌胶团絮体内的部分微生物,且对不同微生物的杀灭效果不同,亚硝酸盐氧化菌(NOB)是最易被杀灭的类型。当次氯酸钠投加量为15 mg/L时,反应3 h后污泥胞外聚合物总含量降低了15. 48%,硝化活性丧失殆尽且再未恢复,反硝化活性下降明显;恢复7 d后,絮体内部微生物可以得到有效恢复,而丝状菌大多依然处于死亡状态,EPS总含量继续下降。总之,高浓度消毒剂作用于活性污泥后,可以达到控制丝状菌的目的,但是污泥的硝化和反硝化活性也受到了影响。     

好氧颗粒污泥发生丝状菌污泥膨胀的控制措施

在SBR反应器内接种好氧颗粒污泥,经驯化后对人工模拟废水的处理效果良好。考察了培养过程中污泥形态的变化以及发生丝状菌污泥膨胀时反应器对污染物的去除效果,并探讨了丝状菌在污泥颗粒化过程中的作用以及控制丝状菌污泥膨胀的方法。结果表明,丝状菌污泥膨胀对COD的去除率有影响,但对去除NH3-N、TP的效果影响不大。通过增加反应器内的水力剪切力对控制丝状菌污泥膨胀有一定的效果,而减小C/N值,均衡进水中的营养可从根本上解决污泥膨胀问题。成熟的好氧颗粒污泥的MLSS约为3 000 mg/L,沉降性能较好,SVI为77 mL/g;对COD、NH3-N、TP均具有较高的去除率,分别达到94.52%9、5%9、0%左右。     

连续流完全混合活性污泥法污泥膨胀对策的研究

连续流完全混合活性污泥法污泥膨胀对策的研究陈纯（湘潭大学）传统的连续流活性污泥法已被广泛应用于有机污水二级处理。然而，其运行中出现的污泥膨胀问题，引起人们广泛重视，并对其做了大量研究。研究表明［１］［２］［３］，活性污泥系统内产生丝状菌性膨胀（本文所...     

低温条件下SBR活性污泥膨胀及控制

通过对实验室SBR中污泥膨胀类型的判别,发现低温条件下污泥膨胀是由非丝状菌过度繁殖引起的。通过试验发现一方面可以通过提高水中溶解氧、降低污泥负荷以及增加排泥次数能有效控制非丝状菌污泥膨胀,另一方面通过投加聚合氯化铝、三氯化铁、聚合硫酸铁等混凝剂可以改善活性污泥沉降性能,但抑制污泥膨胀周期较短,另外投加高锰酸钾氧化剂和聚丙烯酰胺对非丝状菌的抑制效果不明显。     

SBR工艺中污泥负荷对丝状菌污泥膨胀的影响

在严格控制ＳＢＲ工艺试验运行条件下,就污泥负荷对丝状菌污泥膨胀的影响规律进行了研究。结果表明,高污泥负荷不仅不是导致污泥膨胀的因素,而且对污泥膨胀有抑制作用;在污泥负荷降低到一定程度（“临界负荷”）后,ＳＶＩ迅速升高,加速污泥膨胀的发生。还发现,进水底物浓度与“临界负荷”及低于“临界负荷”后污泥膨胀的最大程度ＳＶＩｍａｘ之间呈负相关关系,且都可用微生物的选择性理论来解释。     

A~2/O工艺的污泥膨胀及污泥特性研究

丝状菌污泥膨胀是制约活性污泥工艺发展的重大难题之一,在同步脱氮除磷系统中更容易发生。以城市污水厂中最常采用的A^2／O同步脱氮除磷工艺为研究对象,系统探讨了该工艺中可能出现的丝状茵污泥膨胀及其诱因,并研究了膨胀污泥的特性。结果表明,若运行不当,A^2／O工艺也可能发生丝状菌污泥膨胀;单纯提高好氧区的DO浓度可在一定程度上改善污泥的沉淀特性,而增大好氧区的有机负荷对控制污泥膨胀更为重要。沉淀性能良好的污泥粒径分布范围较广,在15μm和50μm附近也有部分分布,且大多为球菌;膨胀污泥的粒径大多在10μm以下,绝大多数为丝状菌,只有少量球菌被包埋在丝状菌内部。     

Biosorption and dynamics of bacterial populations in activated sludge

Nutritional relations are determining factors in the biological competition between filamentous and floc-forming microorganisms of activated sludge. Biosorption reflects the behaviour of microorganisms in relation to a given substrate. The results obtained from nearly 600 measurements of biosorption carried out in 11 wastewater treatment plants are presented. Biosorption of non-filamentous sludge is less than 30 mg COD/g SS for a 100 mg COD/g SS floc loading. Biosorption increases appreciably with the sludge volume index (SVI). These investigations provide a better understanding of the mechanisms involved in the contact zones. These techniques are successfully experimented in some cases of bulking where biosorption was at least equal to 40 mg COD/g SS.     

Evaluation of alternative sludge settleability indices

Proposed modifications of the standard sludge volume index (SVI) to eliminate its unpredictable variation with suspended solids (SS) concentration include stirring, conduct of the test at constant SS concentration, and dilution. We have tested these modifications by making correlations between the respective indices and the content of filamentous organisms in activated sludge expressed in terms of total extended filament length. The results indicate that diluted SVI is the best index of sludge settleability among those tested. Correlation of diluted SVI with specific functional relationships between settling velocity and SS concentration would enable the application of this parameter to prediction of thickening capacity in secondary clarifiers.     

Model system of bulking and flocculation in mixed culture of Sphaerotilus sp. and Pseudomonas sp. for dissolved oxygen deficiency and high loading

A mixed continuous culture system was made up as a model for bulking and flocculation phenomena of the activated sludge to study the effect of dissolved oxygen (DO) deficiency and the effect of high organic loading. The system consisted of a floc forming bacterium and a filamentous bacterium which were isolated from the activated sludge and were identified as Pseudomonas sp. and Sphaerotilus sp., respectively. Sphaerotilus sp. had potential to cause a filamentous bulking phenomenon on the activated sludge. It was observed that the filamentous microorganism showed three kinds of growth form, filamentous form, pellet form and dispersed form, and that the floc former showed two kinds of growth form, good floc form and dispersed form. In the model system, these changes of growth form of two microorganisms, which could be thought as the cause of settling characteristics changes, depended on the DO level and the dilution rate (as a substitution for organic loading). The DO level also influence the aggregative ability of each microorganism and the maximum oxygen uptake rate, Q_O2max, of filamentous microorganism. The proportions of both microorganisms in model system were inverted reversibly by the DO level or the dilution rate changes.     

Limited filamentous bulking in order to enhance integrated nutrient removal and effluent quality

Limited filamentous bulking has been proposed as a means to enhance floc size and make conditions more favorable for simultaneous nitrification/Denitrification (SND). Moreover a slightly heightened SVI is supposed to increase the removal of small particulates in the clarifier. Integrated nitrogen, phosphorus and COD removal performance under limited filamentous bulking was investigated using a bench-scale plug-flow enhanced biological phosphorus removal (EBPR) reactor fed with raw domestic wastewater. Limited filamentous bulking in this study was mainly induced by low DO levels, while other influencing factors associated with filamentous bulking (F/M, nutrients, and wastewater characteristics) were not selective for filamentous bacteria. The optimum scenario for integrated nitrogen, phosphorus and COD removal was achieved under limited filamentous bulking with an SVI level of 170-200 (associated with a DO of 1.0-1.5 mg/L). The removal efficiencies of COD, TP and NH₄⁺-N were 90%, 97% and 92%, respectively. Under these conditions, the solid-liquid separation was practically not affected and sludge loss was never observed. A well-clarified effluent with marginal suspended solids was obtained. The results of this study indicated the feasibility of limited filamentous bulking under low DO as a stimulation of simultaneous nitrification/denitrification for enhancing nutrient removal and effluent quality in an EBPR process.     

A review of physical relationships between form and function in wastewater biotreatment and a new theory relating activated sludge and biofilm systems behaviour

In this review paper, a physical systems analysis based on thermodynamics has been applied to the observed behaviour of activated sludge as a physical system. The origin of the microecology of activated sludge and its relationship to biofilms and the metabolic consequences of the extracellular polysaccharide (EPS) formation are explained for the first time. Feast‐famine conditions are shown to be the leading candidate for the evolution of the ability of biofilm forming bacteria and activated sludge ‘floc‐formers’ to form EPS. The basis for competition for RBCOD between low F:M filamentous heterotrophic bacteria and ‘floc‐forming’ heterotrophic is presented and its relationship to activated sludge bulking described.