曝气对MBBR联合管式膜MBR处理生活污水的影响及膜污染分析

The membrane fouling analysis and effect of aeration on the performance of MBBR combined tubular membrane MBR system treating domestic wastewater

采用移动床生物膜反应器(MBBR)联合管式膜构建气提式管式膜MBR体系用以处理生活污水,考察了曝气对污水处理效果、膜内气液流态及膜过程的影响,探讨了污泥特性的变化及其对膜污染过程的影响机制。结果表明,气提式管式膜MBR体系下膜出水DO浓度高于混合液,且随着曝气量由50 L·h^(-1)提高至150 L·h^(-1),管式膜内气含率由0.33增至0.60并呈“活塞流”流态,操作周期由6~7 d延长至17 d,膜污染速率由1.54 kPa·h^(-1)降至0.21 kPa·h^(-1),临界通量显著增大;同时,MBBR混合液中EPS总量呈减小趋势,但MBBR内悬浮污泥粒径变小,且膜表面EPS中PN/PS比例显著高于MBBR混合液。膜表面污染阻力构成分析表明,气提式管式膜MBR体系下容易发生膜孔堵塞,膜污染以不可逆污染阻力为主。

The air-lifting tubular MBR system was constructed by a moving bed biofilm reactor(MBBR)combined with tubular membranes for domestic wastewater treatment.The effects of aeration on the wastewater treatment effect,gas-liquid flow pattern in membrane module and membrane process were investigated,and the changes of sludge characteristics and its influence mechanism on membrane fouling process were also discussed.The results indicated that the DO level of the membrane effluent was higher than the mixed solution in air-lifting tubular MBR systems.Moreover,with the increase of the aeration rate from 50 L·h^(-1)to 150 L·h^(-1),the void fraction in the tubular membrane increased from 0.33 to 0.60 and"slug flow"state occurred in the tubular membrane,and the membrane operation time was extended from 6~7 d to 17 d,the membrane fouling rate decreased from 1.54 kPa·h^(-1)to 0.21 kPa·h^(-1)and the critical flux increased significantly.In addition,the total EPS in MBBR mixture showed a decreasing trend,but the particle size of the suspended sludge in MBBR decreased,and the ratio of PN/PS on the membrane surface was significantly higher than the mixture in MBBR system.The composition of the resistance to fouling on the membrane surface showed that the tubular membrane was prone to clogging of the membrane pores,and the membrane fouling was dominated by irreversible fouling resistance.