在线清洗对倒置A^2/O-MBR复合膜污染控制研究

ON-LINE CLEANING FOR FOULING CONTROL ON INVERTED A^2/O-MBR COMPOSITE MEMBRANE

采用自主研发的聚偏氟乙烯-聚对苯二甲酸乙二酯(PVDF-PET)复合膜与倒置A2/O工艺结合的MBR系统,以Na Cl O作为清洗剂对复合膜进行在线化学清洗,考察了Na Cl O在不同清洗周期下对膜污染的控制作用,对膜污染的主要污染物胞外聚合物(EPS)的去除效率及对膜结构和系统稳定性的影响。结果表明,Na Cl O对膜进行在线清洗,单次清洗后TMP恢复率达98%,整个阶段运行时间为24 d;循环清洗中,最初TMP恢复率达100%,运行时间为36 d,随着清洗次数的增加,恢复率逐渐下降,都有效延缓了膜污染进入快速增长阶段。Na Cl O对EPS具有较强的去除效果,相比纯水增加了20%。低含量Na Cl O并未对膜结构及系统的稳定性造成不利影响。

A novel in-situ chemical backfiush method, i.e., chemically assisted maintenance cleaning with NaClO as the principal reagent, was developed for membrane fouling control in A^2/O-MBR system, and the PVDF-PET composite hollow tiber membranes were used as filter. The control effect of membrane fouling by NaClO was investigated during different cleaning periods. Its effect was also studied through the removal efficiency of main pollutants such as extracellular polymeric substance （EPS）, membrane structure and system stability.The results showed that the TMP recovery rate reached 98% in each time of cleaning when NaClO was used in on-line cleaning, and the operation time of this stage was 24 d. In circulation cleaning, the TMP recovery rate reached 100% after the first washing, which gradually decreased after each cleaning, and the operation time of this stage was 36 d. Membrane fouling could be alleviated at both of these stages. The application of NaClO was effective in decreasing the content of EPS in the system, 20% increasing compared with pure water. The membrane structure and the stability of system were affected negatively by low content of NaClO.