【作者】 曲洛娟；

【导师】 梁爽； 殷永泉；

【作者基本信息】 山东大学 ， 环境科学与工程， 2013， 硕士

【摘要】 污泥膨胀是活性污泥处理工艺常见的问题之一,自生动态膜生物反应器(Self-forming dynamic membrane bioreactor, SFDMBR)也不例外。SFDMBR利用过滤初期混合液中的颗粒、胶体以及溶解性有机物在廉价微网基材上的自然吸附／沉积形成自生动态膜(Self-forming dynamic membranes, SFDMs)取得与微滤膜近似的泥水分离效果。因此,SFDM的性质是影响SFDMBR过滤性能的关键因素。而活性污泥作为SFDM的主要成分,其性质的变化必然会对SFDM的性质产生重要影响。丝状菌作为活性污泥的主要组成部分,其含量的多少也必然会影响活性污泥的一些重要性质,从而影响SFDM的过滤性能。因此有必要研究丝状菌对活性污泥性质以及SFDM过滤性能的影响,为SFDMBR的应用和推广提供重要的理论依据。采用统计分析的方法研究丝状菌与活性污泥12个基本性质之间的线性关系,了解丝状菌对活性污泥性质的影响。所研究的污泥基本性质包括颗粒平均粒径(Volume moment mean diameter, Dvm)、颗粒分型维数(Fractal dimension, Df)、相对疏水性(Relative hydrophobic, RH)、胞外聚合物(Extracellular polymeric substance, EPS)、多糖(Polysaccharide, EPSc)、蛋白(Protein, EPSp)、蛋白与多糖的比例(EPSp/EPSc)、粘度(Viscosity)、比好氧速率(Specific oxygen uptake rate, SOUR)、污泥表面电荷(Zeta potential)、污泥沉积指数(SVI)、挥发性物质比例(MLVSS/MLSS)、研究结果表明：丝状菌含量与活性污泥的比耗氧速率(rp=0.966,P=0.000)、颗粒平均粒径(rp=0.82,P=0.02)和粘度(rp=0.765,P=0.045)呈较强的正相关性；与EPSp/EPSc (rp=-0.781,P=0.038)呈较强的负相关性；与颗粒分形维数(rp=-0.733,P=0.061)呈较弱的负相关性。其中比耗氧速率与EPSp/EPSc(rp=-0.781,P=0.038)呈较强负相关性,说明丝状菌含量的增加能够提高污泥活性,且污泥活性的提高导致污泥中多糖的相对含量增加。同时在活性污泥性质中颗粒平均粒径,颗粒的分形维数,EPSp/EPSc以及粘度是影响SFDM过滤特性的重要因素。用所选取的7种不同丝状菌含量的污泥,在SFDMBR中开展批式短期过滤实验,考察不同丝状菌含量污泥对SFDM过滤性能的影响。研究结果表明：无论丝状菌含量多少,SFDMBR运行稳定时都能达到较好的出水效果,出水浊度≤1.5NTU。丝状菌含量是影响稳定运行时SFDMs出水通量和阻力的关键因素。相对于丝状菌含量适宜(FI=2, FI=3,FI=4)的污泥形成的SFDMs,丝状菌缺乏(FI=0, FI=1)和过多(FI=5,FI=6)的污泥形成的SFDMs,出水通量较小且过滤阻力较大。污泥中丝状菌含量适宜时,出水通量较大,过滤阻力较小,运行效果较好。根据SFDMBR的过滤特性,可将其过滤过程分为三个阶段：形成阶段,初期快速污染阶段和稳定过滤阶段。且污泥中丝状菌含量的多少影响着SFDM形成时间以及污染速率,说明丝状菌在SFDM的过滤过程中起重要作用。为了进一步深入分析丝状菌影响SFDM过滤性能的原因,本文进一步分析了不同丝状菌含量污泥形成的SFDM的性质。研究结果表明：丝状菌指数与SFDM的压缩性(rp=0.901,P=0.006)和Dvm (rp=0.947, P=0.001)之间存在较强的正相关性,与EPSp/EPSc (rp=-0.825, P=0.022)和Dr(rp=-0.795.P=0.033)之间存在较强的负相关性。丝状菌对SFDM性质的影响主要表现在三方面：物质组成,颗粒组成以及SFDM的结构。SFDM主要由多糖、蛋白以及混合液中颗粒粒径相对较大的物质组成。且随着丝状菌含量的增加SFDM中多糖的相对含量和颗粒粒径随着增加,分形维数减小。当污泥中丝状菌含量缺乏(FI=0, FI=1)时,形成的SFDMs结构紧凑密实,而当污泥中丝状菌含量过多(FI=5,FI=6)时,形成的SFDMs结构致密且厚度大,不利于SFDMs的过滤；当污泥中丝状菌含量正常(FI=2,FI=3,FI=4)时,形成的SFDMs具有一定网状结构,有利于SFDMs的过滤。因此,在SFDMBR运行过程中,应当控制丝状菌的生长情况,提高SFDM的过滤性能。更多还原

【Abstract】 Sludge bulking in biological wastewater treatment processes often occurs and there is no exception in self-forming dynamic membrane bioreactor (SFDMBR). SFDMBR take advantage of the self-forming dynamic membranes (SFDMs)(i.e. initial "desired" sludge layers developed on the coarse-pore materials) to achieve required solid-liquid separation efficiency. Since the characteristics of SFDM are the significant factors affecting the filtration performance. The characteristics of SFDM are reasonably expected to be significantly affected by sludge properties, which is an important part of SFDM. As the main component of activated sludge, the content of filamentous bacteria is bound to influence some important properties of the activated sludge, thus affecting the filtration characteristics of SFDM. It is necessary to study the effects of filamentous bacteria on the activated sludge properties and the filtration characteristics of self-forming dynamic membranes (SFDMs) to provide important theoretical basis of the application and promotion of SFDMBR.In order to understand the influence of filamentous bacteria on the activated sludge properties, the twelve sludge properties were systematical investigated. Sludge properties includes volume moment mean diameter (Dvm), fractal dimension (Df), relative hydrophobic (RH), extracellular polymeric substance (EPS), polysaccharide (EPSc), protein (EPSp), EPSp/EPSc, viscosity, specific oxygen uptake rate (SOUR), zeta potential, sludge settlement index (SVI) and MLVSS/MLSS. The results showed that filamentous bacteria density had a strong positive effect on SOUR (rp=0.966, P=0.000), Dvm (rp=0.82, P=0.02) and viscosity (rp=0.765, P=0.045), but had a strong negative effect on EPSp/EPSc (rp=-0.781, P=0.038) and a moderate negative effect on Df (rp=-0.767, P=0.044). SOUR was correlated inversely to EPSp/EPSc (rp=-0.781, P=0.038), which indicated that the increase of filamentous bacteria content can improve the activity of sludge, leading to the increase in relative content of polysaccharide. In these characteristics of activated sludge, Dvm, viscosity, EPSp/EPSc and Df were the predominant factors affecting on the filtration characteristics of SFDM.This paper researched the influence of filamentous bacteria on the filtration characteristics of SFDM by a series of short-term filtration experiments about activated sludge with different filamentous bacteria density (FI) in SFDMBR. The results showed that the effluent turbidity was not affected by filamentous bacteria density, and when the SFDMBR run stable, the effluent turbidity was below1.5NTU. Filamentous bacteria content is the predominant factors affecting on the effluent flux and resistance of SFDMs. Relative to the SFDMs formed by the sludge with appropriate filamentous bacteria (FI=2, FI=3, FI=4), the SFDMs formed by the sludge with little filamentous bacteria (FI=0, FI=1) or excessive filamentous bacteria (FI=5, FI=6) had better filtration performance, the effluent flux is larger, the filtration resistance is small. According to the filtration characteristics of SFDMs, the filtration process could be divided into three stages:rapid formation stage, rapid growth stage and steady stage, and they changed as the concentrations of filamentous bacteria, indicating filamentous bacteria play an important role in the filtration process of SFDM.To further understand the reasons that caused these results, the characteristics of SFDM also were studied. And the results indicated that filamentous bacteria density had a strong positive effect on compressibility (rp=0.901, P=0.006) and Dvm (rp=0.947, P=0.001) of SFDM, but had a strong negative effect on EPSp/EPSc (rp=-0.825, P=0.022) and a moderate negative effect on D,(rp=-0.795, P=0.033). Filamentous bacteria mainly affected SFDM in three aspects:the type of material, particle composition and the structure of SFDM. Protein and polysaccharide was the main component of SFDMs regardless of FI, but the filamentous bacteria density had a strong relation with EPSp/EPSc whether in mixture or in SFDM. The SFDMs were made up of relatively large particle in sludge suspension. The structure of SFDMs formed by the sludge with little filamentous bacteria (FI=0, FI=1) was compact and dense; The structure of SFDMs formed by the sludge with excessive filamentous bacteria (FI=5, FI=6) was thickness and non-porous; the strueture of SFDMs formed by the sludge with appropriate filamentous bacteria (FI=2, FI=3, FI=4) was net and porous, which is better to filter. So in the filtration process, the growth of filamentous bacteria should be controlled to improve the filtration performance of SFDM.更多还原