水力停留时间对膜生物反应器膜污染的影响

为考察水力停留时间(hydraulic retention time, HRT)对膜生物反应器(membrane bioreactor, MBR)体系内的混合液特性和膜污染的影响，对兰州某生活污水处理厂生化尾水进行了浸入式中空纤维MBR现场实验。结果表明，在HRT由6 h逐渐升高至12 h的过程中，胞外聚合物(extracellular polymeric substances, EPS)中大分子质量颗粒物的比例、溶解性微生物产物(soluble microbial products, SMP)的含量和污泥的Zeta电位分布均逐渐增大。同时，EPS多糖含量、污泥粒径和黏度均出现逐渐降低的趋势，这些因素可能共同作用导致膜组件的运行时间缩短、过膜压差(transmembrane pressure, TMP)快速增大，最终致使膜污染进程的加快。在HRT为6 h、膜通量15 L·(m²·h)⁻¹、污泥质量浓度为4 000 mg·L⁻¹的条件下，中空纤维式MBR处理生化尾水可以获得较好的混合液特性和处理效果。

Effect of hydraulic retention time on MBR membrane fouling

In order to investigate the effects of hydraulic residence time (HRT) on the mixed liquid characteristics and membrane fouling in a membrane bioreactor (MBR) system, an immersive hollow fiber MBR was used to conduct field experiments treating the biochemical tail water from a wastewater treatment plant in Lanzhou. The results showed that the proportion of macromolecular mass particulate matter in extracellular polymeric substances (EPS), concentration of soluble microbial products(SMP) and Zeta potential distribution of sludge increased gradually when HRT increased from 6 hours to 12 hours. At the same time, the decreasing trends occurred for the concentration of EPS polysaccharide, sludge particle size and viscosity, and their combined effects led to the reduction of the running time and the rapid increase of the transmembrane pressure (TMP), finally the process of membrane fouling was accelerated. Good mixed liquid characteristics and treatment effect were obtained when the biochemical tail water was treated by hollow fiber MBR under the conditions of HRT of 6 hours, membrane flux of 15 L·(m2·h)−1 and sludge mass concentration of 4 000 mg·L−1.