The Analysis Of EPS And Sludge Characteristics Under Different Working Conditions In The IBR

Integrated biological reactor(IBR) is a single continuous flow intermittent aeration activated sludge treatment process. The reactor can achieve good removal effect of COD,nitrogen and phosphorus under different working modes, but the good removal effect of the reactor is intimately associated with the floc shape, structure, function and characteristics of activated sludge. Extracellular polymeric substances(EPS) has an important impact on settlement, flocculation, surface characteristics and hydrophobicity of activated sludge, which will influences system stability, removal efficiency and effluent quality ultimately. However, so far, conclusions about the effect of EPS on flocculation , settlement and hydrophobicity of the flocs and their relevance to effluent quality vary from person to person. From the analysis, this might be relevant to the methods of EPS extraction and determination of the components. In view of this, on the authority of previous research, the thesis groups different approaches to EPS extraction and determination of each component in the present experimental conditions. Meanwhile, in the thesis, the activated sludge in test scale system is taken as the subject investigated. Four optimum intermittent operation modes are selected to explore variation laws of sludge flocculation, sedimentation, hydrophobicity and content of EPS in different operating modes, including comparative analysis between them. The main conclusions of the research are as followed:(1) Extraction and determination of EPS components:Protein, humic acid and DNA are extracted by ultrasonic plus resin extraction method and polysaccharides extracted by heating; Anthrone-sulfuric acid method is used for determinating polysaccharide, the modified Folin-Lowry for protein and humic acid, and diphenylamine for DNA.(2) The analysis of EPS and sludge characteristics: The amount of EPS and its components change little under the same working mode. There is a significant positive correlation between reflocculation ability and the content of EPS under working conditionⅡand conditionⅣ. It means that the more EPS content, the stronger the sludge flocculation ability. Between different operating conditions, FA basically shows the same variation with EPS. In the same operating cycle and aeration ratio, flocculation ability is proportional to the content. However, FA has nothing to do with the content of EPS between various operating conditions with different operating cycles.Whether under the conditions or not, it shows a significant positive correlation between EPS content and SVI. That is to say, the increase in EPS content is not conducive to sludge settling. ConditionⅠhas a best performance of sludge settling. Under different conditions, EPS presents a positive correlation to the relative hydrophobicity, and conditionⅢis particularly significant. While there is no significant correlation between EPS and SRH, SRH show a consistent trend with sludge settling characteristics.(3) The analysis of EPS and water quality: The reactor can achieve good removal efficiency of COD under different conditions. The amount of EPS and the removal efficiency of COD shows a significantly positive correlation under conditionⅠand conditionⅣ; The removal efficiency of ammonia nitrogen is high and relatively stable, they have the same trend under different conditions generally.While the removal efficiency shows no significant correlation to the change of EPS; The average removal efficiency of TN is first increased and then decreased,which is the same to the trend of EPS content between different working conditions. The nitrate content of effluent water shows an opposite trend with the variation of TN; The average removal rate of TP has great fluctuations under different working conditions, and it is consistent with the variation of the amount of EPS between different working conditions.(4) The selection of optimal condition: ConditionⅡis ultimately selected as the relatively optimal condition after comparative analysis of sludge characteristics and water quality.