【作者】 刘珊；

【导师】 张锡辉； 张金松；

【作者基本信息】 清华大学 ， 环境工程（专业学位）， 2016， 硕士

【摘要】 膜生物反应器（MBR）在污水处理领域应用越来越广,其特点是出水水质波动小,占地面积小等,但高能耗及膜污染问题一直限制其推广应用。本文研究比较了MBR在溶解氧浓度逐步降低情况下的处理效果。采用高通量测序方法分析了活性污泥微生物群落结构的变化规律。剖析了膜污染主要成份,包括颗粒、胶体粒子及有机物分子等,比较了直接投加H₂O₂和NaClO对活性污泥性能和膜污染的影响。论文试验所用MBR处理规模为100t/d,试验运行时间为260d,溶解氧浓度分为三个梯度:好氧状态下,DO>2.0 mg/L,运行160d;低氧状态下,0.5 mg/L<DO<2.0 mg/L,运行40d;微氧状态下,DO<0.5 mg/L,运行60d。MBR运行状态从好氧状态逐渐变为微氧状态,对N、P的去除率上升,污泥浓度逐渐变大。微氧MBR出水COD、氨氮、总氮的浓度分别为24.3 mg/L、2.8 mg/L、7.5 mg/L,符合国家城镇污水处理厂出水一级A标准。在微氧状态下,微生物群落多样性不断降低,没有检出NOB细菌。因此,微氧状态强化了MBR短程反硝化,有利于去除TN。活性污泥中存在的蛋白质类大分子物质,其能够从活性污泥菌胶团颗粒混合液中向膜表面凝胶层迁移,加剧膜污染。偏向厌氧状态的厌氧污泥,其粒径较小、抗压缩性较差,其含有的蛋白质类物质能够进入凝胶层,使膜污染加快;胶体粒子、有机物对膜污染影响大。投加H₂O₂剂量在200 mg/L范围内,能够提高活性污泥的过滤性能,但是抑制影响微生物的活性,顺序为:硝化细菌>聚磷菌>反硝化细菌。投加量为10 mg/L时,污泥过滤性能最好。投加10 mg/LNaClO剂量,可提高污泥的密实度,增加其抗压缩性,从而改善污泥的过滤性能。但是,高剂量NaClO会加速膜污染,甚至导致活性污泥解体。更多还原

【Abstract】 Membrane bio-reactor（MBR）has been applied more and more in wastewater treatment,because of its promising water quality and low land space.However,high energy cost and membrane fouling as shortcomings hinder the practical application of MBR.This thesis studied the performance of pollutants removal when dissolved oxygen（DO）in MBR decreased gradually.High-throughput genic method was used to explore bacterial community structures during MBR operation.The foulant composition was analyzed including colloid particles and organic matters.H₂O₂ and NaClO were compared to better control membrane fouling,and their influence on microbial activity and filtration performance were characterized.A pilot-scale MBR with a capacity of 100t/d was operated for 260 days during experiments,related DO concentrations were modified following three different stages: the first is aerobic stage for 160 days with DO>2.0 mg/L,then low DO stage for 40 days with DO between 0.5 mg/L and 2.0 mg/L,final is micro-DO stages for 60 days with DO<0.5 mg/L.It was found that,during transition from aerobic to micro-DO stages,MLSS increased gradually,and the removal to N and P got improved.The effluent concentrations of COD,ammonia-nitrogen,total-nitrogen for MBR at micro-DO condition were 24.3 mg/L,2.8 mg/L,7.5 mg/L,respectively,reached to the standard of municipal wastewater treatment.DO modification resulted in the changes of microbial community in both composition and activity.At micro-DO stage,no NOB bacteria were detected.Thus micro-DO condition did strengthened the processes of shortcut denitrification,which is good to TN removal.It was found that there were some protein compounds existed in active sludge,which can deposit on gel-layer on the surface of membrane,thus worsen the membrane fouling.The active sludge at micro-DO condition was characterized with small floc and poor compression resistance,in which the macro-molecular proteins can migrate into the gel layer,may lead to serious membrane fouling.It was indicated that both sludge colloid and organics influence to the membrane fouling significantly.It was showed that H₂O₂ can improve the collection of sludge in ultra-filtration at the dosage of <200 mg/L.Functional microorganisms can be inhibited by H₂O₂ under following sequence: nitrifying bacteria > phosphate accumulation organismsbacteria >denitrifying bacteria.It was recommended that addition of 10 mg/L H₂O₂ was the best to ameliorate sludge performance.Addition of 10 mg/L NaClO can strengthen the filtration performance of sludge,resulting in formation of dense and tough particles.However,higher dosage of NaClO deteriorated the membrane fouling probably due to sludge disintegration.更多还原