【作者】 曹占平；

【导师】 张宏伟；

【作者基本信息】 天津大学 ， 环境工程， 2009， 博士

【摘要】 作为一种新型高效的水处理技术,MBR已成为目前研究和应用的热点之一。然而,膜污染是当前限制MBR广泛应用的一个主要障碍。本文以一体式中空纤维膜生物反应器为研究对象,主要考察了污泥龄(SRT)和丝状菌对MBR工艺混合液特性的影响,并研究了混合液特性对膜污染的影响机理,同时对MBR工艺的调控技术进行了探讨,这对MBR工艺膜污染的有效控制具有重要理论和实用价值。本文的研究内容主要包括以下几方面:研究了污泥龄对EPS总量、TB和LB含量及其中蛋白质和多糖比例的影响。研究结果表明,随污泥龄的延长,混合液EPS总量增加,TB和LB中蛋白质与多糖比例发生变化,这改变了细菌表面电荷,增大了细菌表面亲水基和疏水基的比例,使细菌存在状态由不稳定型(R型)向稳定型(S型)转变,降低了混合液Zeta电位,同时使SVI值增大。采用SPSS软件对膜的主要污染因子进行了统计分析,其相关系数分别为:Zeta电位(rp=-0.818)、上清液悬浮固体SSs浓度(rp=0.853)、相对疏水性(rp=0.832)。研究了MBR工艺在不同SRT条件下的微生物特性及膜出水水质,提出了预测MBR工艺污泥浓度的模型,并对SRT的控制提出了理论依据。MBR中微型动物群落结构随SRT的延长,呈现了规律性变化,对MBR的运行有指示作用。本文以Langmuir理论和Darcy定律为基础,从理论上证实了浓度极化阻力与凝胶层阻力是同一性质的力并通过Langmuir关系式统一起来,推导了微滤膜过滤阻力的数学模型。采用2个平行运行的反应器研究了进水限氮和限磷对MBR工艺处理效果及丝状菌膨胀的影响。进水限氮时MBR处理效果明显降低,丝状菌的生长丰度指数增加。丝状菌型污泥膨胀使混合液和膜表面的疏水性都增加,Zeta电位降低,加速了污染物在膜表面的沉积和吸附,从而造成严重的膜污染。研究发现上清液悬浮固体浓度SSs、混合液Zeta电位、相对疏水性是造成膜污染主要因子,采用控制SRT、投加活性炭及间歇出水的操作方式能有效地控制膜污染。更多还原

【Abstract】 MBR, as a new highly effective water treatment technology, has attracted the increasing attentions of the researchers. However, a major obstacle to the wide application of MBR is the membrane fouling. This paper, using the submerged hollow-fiber MBR, mainly investigated the effects of sludge age (i.e. sludge retention time, SRT) and filamentous bacteria on mixed liquor characteristics, and the effects of mixed liquor on membrane fouling mechanism. Meanwhile, the regulative technology of MBR is also discussed. The research has significance in its theory and application for effective control of membrane fouling.The main research work of this paper is as follows:The effects of SRT on the extracellular polymeric substances (EPS), the concentration of tightly bound EPS (TB) and loosely bound EPS (LB) and the ratios of protein and polysaccharide in TB and LB have been investigated. The results showed that the total EPS increased and the ratios of protein and polysaccharide in tightly bound EPS (TB) and loosely bound EPS (LB) changed with the extension of SRT, which influenced the surface charge of bacteria, increased the proportion of hydrophilicity base and hydrophobicity base on the surface of bacteria, changed the existence state of bacteria from the instable (R type) to the stable (S type), decreased the Zeta potential and enhanced simultaneously sludge volume index (SVI). Statistical analysis for the main parameters of fouling resistance has been performed by SPSS software, and it was found that the correlation coefficients (rp) were -0.818 for Zeta potential, 0.853 for the concentration of suspended solids in supernatant and 0.832 for relative hydrophobicity, respectively.The microorganism characteristic and the effluent quality of MBR under the different SRTs have been investigated, the model of the sludge multiplication dynamics to forecast the sludge concentration, and the theory basis on controlling SRT of MBR has been proposed in MBR. Microfauna community structure in MBR presented the regular variation along with the SRT extension, which has instructive function to the movement of MBR.Based on the Langmuir theory and the Darcy law, the paper confirmed that polarization resistance and the gel level resistance are the identical nature resistance by theory analysis and correlated them by Langmuir formula. The mathematical model of the micro-filtration resistance was also derived.By the comparison experiments for two MBRs, the effects of the conditions of nitrogen-deficiency and phosphorus-deficiency on the removal efficiency and the bulking of filamentous bacteria have been investigated. The removal efficiency of MBR reduces obviously and filamentous index (FI) is higher, when nitrogen is limited. Filamentous sludge bulking results in higher hydrophobicity in both mixed liquor and membrane surface and lower Zeta potential, which accelerate the pollutant deposition and adsorption on the membrane surface, thus causes the more serious membrane fouling.The research discovered that the supernatant suspended solid concentration (SSs), Zeta potential and relative hydrophobic are main influence factors of membrane fouling. The control of SRT, addition of PAC and the batch operation of flux can control the membrane fouling effectively.更多还原