膜生物反应器中膜过滤特征及膜污染机理的研究

以膜生物反应器处理市政污水,通过对活性污泥进行终端过滤来反映膜污染机理,实验表明,最初很短时间内膜污染受膜孔堵塞模型控制,之后受沉积层阻力模型控制,后一阶段是膜污染的主要控制阶段;膜的相对通量随过滤时间呈指数衰减趋势,压力越大,通量衰减越快;污泥沉积层存在压密过程,这一过程中的污泥比阻随压力增大而增大,并得到处理市政污水的污泥压密指数为0.807 8;阻力分布实验表明沉积层阻力占总阻力的90%以上,是膜过滤污染阻力的主要组成部分;活性污泥各组分对膜污染均有贡献,其中悬浮固体、胶体颗粒和溶质产生的阻力分别占87.98%、6.20%和5.82%;根据实验和计算结果,探讨了MBR处理市政污水过程中可能的膜污染机理.

Filtration Characteristics and Mechanism of Membrane Fouling in a Membrane Bioreactor for Municipal Wastewater Treatment

Filtration characteristics and mechanism of membrane fouling were investigated with MBR mixed liquor. It was found that, the variation of filtration resistance was fit to the standard blocking filtration model in initial process, and then fit to cake filtration model in later process. In dead-end filtration of sludge, the relative flux was in the tendency to the exponential decay along with filtration time, and flux was decreased more quickly at higher pressure. Sludge was compressed during filtration process, and resistance of sludge was increased with the increase in filtration pressure, the compressibility index was obtained as 0.807 8. Quantitative calculations showed that cake resistance made up over 90% of total resistance. In addition, the relative contribution of each of the sludge fractions to membrane was respectively calculated as 87.98 % for suspended solids, 6.20 % for colloids and 5.82% for solutes. Then a possible mechanism underlying membrane fouling was proposed.