错流速度对外置式MBR处理生活污水的影响

采用外置式管式膜生物反应器处理模拟生活污水,研究了系统对COD、NH4^+-N和浊度去除状况,考察了错流速度对污染物去除效果及膜污染影响。结果表明,COD和NH4^+-N去除率均达93%以上,且错流速度对系统出水水质影响较小,但较高的错流速度容易使出水浊度增加。错流速度由0.56 m/s增至2.20 m/s,膜污染周期由10 d增至20 d,化学清洗频次减少,膜临界通量由30~40 L/(m^2·h)增至70~80 L/(m^2·h)。错流速度会改变膜表面污染阻力构成,而较高的错流速度容易使膜表面发生不可逆污染,不利于膜长周期操作运行。

Effect of Cross-Flow Rate on Recirculated Membrane Bioreactor for Domestic Wastewater Treatment

The removal efficiency of COD,ammonia nitrogen and turbidity were researched in the recirculated membrane bioreactor for treating simulated domestic sewage.The effects of cross-flow rate on pollutant removal and membrane fouling were also investigated.The results showed that the removal rates of COD and ammonia nitrogen were over 93%,and the effluent quality was less affected by the cross-flow rate.However,a higher cross-flow rate led to increase of the effluent turbidity.With the cross-flow rate increasing from 0.56 m/s to 2.20 m/s,the membrane operation time increased from 10 d to 20 d,the frequency of chemical cleaning decreased,and the membrane critical flux increased from 30~40 L/(m~2·h)to 70~80 L/(m~2·h).The fouling resistance of membrane surface was changed by cross-flow rate,and the irreversible membrane fouling was easy to occur with higher cross-flow rate,which was not conducive to long-term operation of membrane.