在汲取液中投加化学清洗剂控制压力延滞渗透膜生物反应器膜污染的研究

Membrane fouling control in pressure retarded osmotic membrane bioreactor by adding chemical cleaning reagent in draw solution

压力延滞渗透膜生物反应器(PROMBR)是一种将压力延滞渗透(PRO)技术与活性污泥法相结合的新型污水处理工艺,可以实现水和能量的同步回收.然而,由于正渗透(FO)膜的多孔支撑层朝向组成复杂的活性污泥,导致PROMBR的膜污染严重.本文借助在汲取液中添加化学清洗剂来实现PROMBR膜污染的原位控制.结果表明,在汲取液中投加化学清洗剂可以利用反向渗透将清洗剂输送到FO膜支撑层,从而实现膜污染物的去除.在汲取液中投加HCl可以显著提升FO膜的运行通量,而在汲取液中投加NaClO无法提升FO膜的运行通量.投加HCl对FO膜支撑层表面和孔内的有机污染和生物污染影响不大,但是可以有效缓解无机污染.投加NaClO能够有效减少FO膜支撑层表面和孔内的有机污染和生物污染,但是对无机污染没有影响.相比于有机污染和生物污染,无机污染对PROMBR中FO膜通量下降的贡献更大.

Pressure retarded osmosis membrane bioreactor(PROMBR)combining pressure retarded osmosis(PRO)technology and activated sludge process has been developed for simultaneously recovering water and energy from wastewater.However,forward osmosis(FO)membrane fouling was severe in the PROMBR owing to the porous support layer of FO membrane facing activated sludge.In this study,it was attempted to control FO membrane fouling in the PROMBR by adding chemical cleaning reagents in the draw solution.The results indicated that it was feasible to control FO membrane fouling via directly adding suitable chemical cleaning reagents in the draw solution.Adding HCl into the draw solution could effectively enhance the water flux of FO membrane while adding NaClO had no impacts on FO membrane flux.Although adding HCl into the draw solution could not mitigate biofouling and organic fouling of the support layer,it could effectively alleviate inorganic fouling of the support layer.With regard to adding NaClO into the draw solution,it could alleviate organic fouling and biofouling of the support layer,but had no impacts on inorganic fouling of the support layer.Comparing with the organic fouling and biofouling,inorganic fouling had a more contribution to the flux decline of FO membrane in the PROMBR.