To clarify the effect of sludge retention time (SRT) on performance and microbial behaviour in a submerged membrane bioreactor for the treatment of domestic wastewater, four runs of a laboratory scale reactor with hydraulic retention time of 5h and SRTs of 5, 10, 20 and 40 days, respectively, were conducted. The membrane bioreactor process was capable of achieving over 90% removals both for chemical oxygen demand and ammonia nitrogen, on average, almost independent of SRT. With prolonged SRT, concentrations of suspended solids and volatile suspended solids in the bioreactor increased accordingly, whereas sludge growth kinetic parameters, sludge yield and endogenous decay coefficients, declined slightly and exponentially, respectively. The mean sludge particle sizes at different SRTs were in the range 14.82-48.24m, providing a favourable environment for enhancement of mass transport. Characterized by an oxygen consumption rate, sludge specific activities both for organic decomposition and nitrification of ammonia nitrogen varied with SRT. However, volumetric oxygen consumption rates of the membrane bioreactor, representing the whole ability of the process for decomposing pollutants, were enhanced as SRT increased.

采用悬浮生长型和两种附着生长型膜生物反应器（MBR）处理微污染源水，考察了各种MBR的膜污染特征及清洗情况。通过电镜观察污染膜表面，发现不同MBR 的膜外表面污染特征不同，而膜内表面均无明显污染。对污染膜进行物理和化学清洗试验表明，常规物理清洗可使滤饼层大部分脱落，但对膜过滤性能的恢复效果较差；碱洗对膜过滤性能的恢复作用显著，有机污染对膜阻力的“贡献”最大。附着生长型MBR的污染膜表面粘性较大，常规物理清洗效果差，采用超声波清洗可使膜过滤性能恢复约30%，与超声波结合的化学清洗效果优于常规化学清洗。对膜污染化学洗脱液成分的分析表明，MBR中的膜污染与混凝—微滤膜组合工艺（C-MF）相比，有机污染物含量较高，Ca元素含量较低，腐殖质组分略高。两种工艺条件下洗脱液中溶解性有机污染物均以小分子有机物为主；与C-MF 相比，MBR的膜污染洗脱液中大分子有机物增多，推测与反应器内微生物代谢产物的产生有关。

对地下渗滤系统处理生活污水的氮磷去除机理进行了研究。结果表明，在2cm/d的水力负荷下，系统对氨氮、COD、总磷的去除率可达到90%以上；出水中氨氮、COD、总磷分别低于0.2,30，0.025mg/L；系统对总氮亦有良好的去除效果，达3.5%。强化布水措施可以有效地提高系统对污染物质的去除率。地下渗滤系统中通过硝化、反硝化作用可以去除约50%的进水总氮，是地下渗滤系统去除氮的主要途径。改善条件以促进反硝化反应是提高地下渗滤系统总氮去除率的关键。土壤吸附与沉淀作用是地下渗滤系统去除磷的主要途径。

Hydraulic characteristics in a membrane bioreactor are of significance for retarding membrane fouling and maintaining stable operation. Cross flow velocity along the membrane surface and its effect on transmembrane pressure change were experimentally.

Bath wastewater is an ideal wastewater-reclamation source for its large discharge amount, simple pollutant composition and low pollutant content. The feasibility of reclaiming bath wastewater with a membrane bioreactor was investigated in apilot plant of 10m3 per day at an organic load of 0.50-1.85kg-COD/(m3 per day). The operation was continued for 216 days without sludge discharge and chemical cleaning of membrane modules. The quality of the effluent obtained met the wastewater reclamation standard of China, with COD<40mg/l, NH4+−N<0.5mg/l and anionic surfactant (AS)<0.2mg/l. Biological treatment removed most pollutants in the influent, degrading 34-85% of COD and 98% of anionic surfactant. The membrane separation balanced the unstable biological treatment of COD but demonstrated no contribution to anionic surfactant removal. Inorganic substances were found to accumulate in the bioreactor. The main reason for membrane fouling was considered to be sludge adhesion and gel layer formation over the outer membrane surface and microbial growth over the inner membrane surface.