丝状菌污泥膨胀理论分析

对丝状菌污泥膨胀现象进行了综合分析,并在广义Monod方程的基础上基本统一了污泥膨胀理论和建立了相关的数学模型。该模型可以很好地解释由基质限制、DO限制、营养物缺乏、pH和H2S等因素引起的丝状菌污泥膨胀。利用广义Monod方程采用双基质限制（碳源和溶解氧）模型和系统动力学方程进行了计算机模拟研究,对有机负荷、DO、水质和水量变化等因素对细菌和丝状菌的竞争影响进行了深入的探讨,并在此基础上针对不同的污泥膨胀类型提出了相应的控制策略。     

丝状菌污泥膨胀的原因及其控制方法

对引起丝状菌污泥膨胀的几种原因作了分析，并介绍了在实际生产中控制污泥膨胀的方法，同时探讨了在设计过程中应注意的问题。     

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。     

桐乡市城市污水处理厂对丝状菌污泥膨胀的控制实践

介绍了桐乡市城市污水处理厂丝状菌污泥膨胀的处理对策,对发生污泥膨胀时的水质特点、工况条件进行分析,认为此次丝状菌污泥膨胀主要是由于低污泥负荷率、低溶解氧引起的。通过调整泥龄、污泥负荷、DO等运行参数,投加NaClO溶液杀灭丝状菌等措施成功控制了此次污泥膨胀,可供同行参考。     

丝状菌颗粒污泥形成过程及其对膨胀控制的启示

通过试验和观察,从粒径、密度、沉速、基质交换和孔隙率等方面对比分析了丝状菌颗粒污泥与普通好氧颗粒污泥、黑色颗粒污泥的异同,同时研究了丝状菌颗粒污泥的形成过程及丝状菌的缠绕特性与演替规律。研究表明丝状菌对于聚集体的形态有一定的选择性,而且易于被改造的丝状菌结构与丝状菌的类型也有一定的关系;另外,剪切力及丝状菌网眼的尺寸在丝状菌污泥颗粒化过程中亦具有重要意义。最后论证了通过颗粒化技术改变丝状菌发散式生长模式使其自我缠绕致密生长的可行性,为丝状菌污泥膨胀控制提供了一种新思路。     

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.     

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。     

SBR非丝状菌污泥膨胀模型的构建

以序批式反应器(SBR)为试验系统,采用以乙酸钠、葡萄糖为基质的人工配水为进水,通过固定溶解氧浓度、不断调整进水C/N值和有机负荷,从污泥宏观及微观角度综合研究了C/N值对SBR系统的影响并成功构建了SBR非丝状菌污泥膨胀模型.结果发现:当进水C/N值为52、有机负荷为1.O～1.5 ks/(kg·d)、溶解氧为5～7 mg/L时即可快速引起非丝状菌污泥膨胀;此外,在构建的非丝状菌污泥膨胀模型中,活性污泥的沉降性能虽然变差、出水浑浊、透明度差,但仍具有高效去除COD和NH<'+><,4>-N的能力,对二者的去除率仍能达到90%以上.     

活性污泥丝状菌的膨胀机理

从宏观和微观两方面分析了丝状菌性污泥的膨胀机理 ,就目前提出的众多假说中的表面积 /体积假说和选择性原则作了进一步的阐述 ,解释了丝状菌性污泥的膨胀问题     

控制完全混合式曝气池污泥膨胀的生物选择器

污泥膨胀是完全混合式曝气池(CMR)普遍存在的运行难题。CMR的污泥膨胀主要由一类易于在低F/M条件下过度增殖的丝状菌所引起,其典型代表为M.Parvicella。控制低F/M条件下污泥膨胀的有效方法之一是在CMR前加一个生物选择器,局部提高F/M,选择性发展菌胶团等常规微生物,在短时间内吸附、贮存水     

Effect of anaerobic conditions on activated sludge filamentous bulking in laboratory systems

The effect of anaerobic conditions on the occurrence of filamentous microorganisms in the biocenosis of activated sludge has been studied in laboratory systems. These systems consisted of an anaerobic completely mixed tank followed by an oxic one. A single oxic completely mixed tank served as a control unit. Synthetic wastewater was used incorporating glucose and ethanol as a carbon source in order to support the growth of filamentous microorganisms in completely mixed tanks. It has been demonstrated that the growth of some filamentous organisms, for instance Type 021N and Sphaerotilus natans, was suppressed under anaerobic conditions as a result of lower rates of polyphosphate depolymerization under anaerobic conditions. However, the positive effect of the anaerobiosis may be eliminated if simultaneous dissimilatory sulphate reduction occurs. In this case filamentous bulking caused by presence of such microorganisms like Thiothrix is possible.     

Control of activated sludge filamentous bulking: Experimental verification of a kinetic selection theory

Two laboratory activated sludge systems, completely-mixed and selector-type, were continuously fed with a multi-component substrate. With excess biomass from both systems, the maximum substrate removal rates, r_x.m, and the half-velocity coefficients, K_s, were determined by means of a simple respirometric method. The following substrates were tested: glucose, galactose, acetic acid, valeric acid, citric acid, glutamic acid, alanine, tyrosine, methylalcohol, ethylalcohol and phenol.It has been found that both the r_x.m and the K_s are basically lower with the mixed cultures cultivated in a completely-mixed reactor (filamentous) than with those cultivated in a selector-type reactor (non-filamentous). The results have experimentally verified a kinetic selection theory in mixed cultures published previously.     

A simplified kinetic model to simulate soluble organic substances removal in an activated sludge aeration tank

A simple kinetic model for the removal of soluble organic substances, SOS, in the activated sludge aeration tank was proposed. The model consists of the instantaneous biosorption of SOS in the influent wastewater and the consecutive biooxidation of the remaining SOS in contact with the activated sludge under the aerated condition. By using samples taken from a municipal wastewater treatment plant, model parameters such as the amount of instantaneous biosorption and the rate of biooxidation, respectively, of SOS were empirically determined, and given as a function of soluble COD concentration. By combining the obtained kinetic data of SOS removal with the quantitative information of the liquid mixing characteristics in a multi-staged aeration tank, a mathematical model to simulate the distributions of SOS concentration in the aeration tank was presented. The simulation calculation was illustratively carried out and the results were shown in comparison with the experimental data in the same plant.     

Control of activated sludge filamentous bulking—VI. Formulation of basic principles

Overgrowing of filamentous micro-organisms in activated sludge is affected by the following factors: (a) composition of treated waste water; (b) actual concentration of dissolved oxygen in an aeration tank; (c) actual concentration of soluble substrate under which micro-organisms grow; (d) technological parameters of the process (sludge loading and age). All these factors were analysed and discussed in the light of the formulated basic principles for control of filamentous bulking.     

光大水务济南一厂污泥膨胀的调控

针对光大水务济南一厂的丝状菌污泥膨胀问题,从F／M、进水中硫化物浓度、微量金属元素等方面进行了分析和工艺调控,结果表明：①由于进水浓度偏低,在小水量、低负荷[F／M〈0．02kgBOD5／（kgMLVSS&#183;d）]、MLSS为2000～4000mg／L时,发生了严重的污泥膨胀。②在小水量、低负荷下,采用间歇曝气不能防止污泥膨胀的发生。③射流曝气系统并不能防止低负荷污泥膨胀的发生。④在设计水量下运行,F/M应提高到0．25kgBOD5／（kgMLVSS&#183;d）左右。通过三个月的调整,SVI降至140mL／g。⑤当SVI为140—200mL／g、污泥呈微膨胀时,出水COD为35mg／L左右,SS为6mg／L左右,此时保持F／M基本不变,SVI缓慢下降;但当DO降低后,SVI又重新升高。⑥通过投加低成本的亚铁盐在短时间内取得明显的控制和消除生物泡沫效果,然后将F/M肘增至0．55kgBOD5／（kgMLVSS&#183;d）,SVI由原来的400mL／g以上降至200mL／g以下,再保持F／M为0．3kgBODs／（kgMLVSS&#183;d）左右,SVI达到最佳值（100mL／g左右）。     

Control of activated sludge filamentous bulking—VII. Effect of anoxic conditions

The effect of anoxic conditions on the occurrence of filamentous organisms in mixed cultures was studied in laboratory activated sludge systems. It was repeatedly demonstrated that anoxic conditions are able to suppress the growth of some undesirable filamentous organisms, for instance, type 021N and Sphaerotilus natans. It was also found that severely filamentous mixed cultures had maximum rates of denitrification or nitrate respiration one order of magnitude lower than non-filamentous mixed cultures. On the basis of these findings it is concluded that some filamentous organisms cannot use nitrate nitrogen as an electron acceptor.     

低溶解氧污泥微膨胀前后污泥硝化活性的对比研究

为了研究低溶解氧微膨胀前后污泥硝化活性的变化,采用SBR反应器,平均DO浓度为0.6 mg/L~0.9 mg/L,测定污泥微膨胀前后污泥氧消耗速率曲线。结果表明：发生污泥微膨胀后,活性污泥对COD的去除能力有较大的提高,而对氨氮去除能力却有一定的下降。污泥微膨胀前后的氧消耗速率曲线显示,微膨胀前活性污泥总活性为67.72 mgO2/gVSS·h,其中硝化活性为43.12 mgO2/g VSS·h,占其总活性的63.67%;而微膨胀后活性污泥总活性为90.49 mgO2/gVSS·h,其中硝化活性为2     

Including the effects of filamentous bulking sludge during the simulation of wastewater treatment plants using a risk assessment model

The main objective of this paper is to demonstrate how including the occurrence of filamentous bulking sludge in a secondary clarifier model will affect the predicted process performance during the simulation of WWTPs. The IWA Benchmark Simulation Model No. 2 (BSM2) is hereby used as a simulation case study. Practically, the proposed approach includes a risk assessment model based on a knowledge-based decision tree to detect favourable conditions for the development of filamentous bulking sludge. Once such conditions are detected, the settling characteristics of the secondary clarifier model are automatically changed during the simulation by modifying the settling model parameters to mimic the effect of growth of filamentous bacteria. The simulation results demonstrate that including effects of filamentous bulking in the secondary clarifier model results in a more realistic plant performance. Particularly, during the periods when the conditions for the development of filamentous bulking sludge are favourable – leading to poor activated sludge compaction, low return and waste TSS concentrations and difficulties in maintaining the biomass in the aeration basins – a subsequent reduction in overall pollution removal efficiency is observed. Also, a scenario analysis is conducted to examine i) the influence of sludge retention time (SRT), the external recirculation flow rate (Q_r) and the air flow rate in the bioreactor (modelled as k_La) as factors promoting bulking sludge, and ii) the effect on the model predictions when the settling properties are changed due to a possible proliferation of filamentous microorganisms. Finally, the potentially adverse effects of certain operational procedures are highlighted, since such effects are normally not considered by state-of-the-art models that do not include microbiology-related solids separation problems.     

Wastewater treatment in a deep aeration tank

Pilot-scale experiments were conducted to investigate the performance of a deep aeration tank (DAT) (10 m deep) treating a high-strength synthetic wastewater and the DAT biokinetics. At the mean cell residence of 2 days or at the food to microorganisms ratio of 1.41 and less, the DAT reactor, operating continuously as completely mixed and without cellular recycle, removed more than 95% of the chemical oxygen demand of the wastewater. The treatment kinetics were observed to follow the Lawrence and McCarty's models in which the values of the kinetic constants Y, k_d, k and K₃ for this particular operating condition were found to be 0.53, 0.085, 9.25 day^?1 and 259 mg 1^?1, respectively. The results of solid separation by flotation, using the hydrostatic pressure developed in the DAT reactor, were satisfactory. However, better flotation results can be expected with the proper design and operation of the flotation tank.