标题：Fatty acid fouling of forward osmosis membrane：Effects of pH,calcium,membrane orientation,initial permeate flux and foulant composition
作者：Pin Zhao;Baoyu Gao;Qinyan Yue;Pan Liu;Ho Kyong Shon
作者机构：Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering,Shandong Universit 更多
关键词：Forward osmosis;Membrane fouling;Octanoic acid;Water flux;Reverse solute flux;
摘要：Octanoic acid(OA) was selected to represent fatty acids in effluent organic matter(EOM). The effects of feed solution(FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmosis(FO) were investigated. The undissociated OA formed a cake layer quickly and caused the water flux to decline significantly in the initial 0.5 hr at unadjusted p H 3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated p H of 9.00. Moreover, except at the initial stage, the sudden decline of water flux(meaning the occurrence of severe membrane fouling) occurred in two conditions: 1.0.5 mmol/L Ca2+, active layer facing draw solution(AL-DS) and 1.5 mol/L Na Cl(DS); 2. No Ca2+,active layer-facing FS(AL-FS) and 4 mol/L Na Cl(DS). This demonstrated that cake layer compaction or pore blocking occurred only when enough foulants were absorbed into the membrane surface, and the water permeation was high enough to compact the deposit inside the porous substrate. Furthermore, bovine serum albumin(BSA) was selected as a co-foulant.The water flux of both co-foulants was between the fluxes obtained separately for the two foulants at p H 3.56, and larger than the two values at p H 9.00. This manifested that, at p H 3.56,BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at p H 9.00, the mutual effects of OA and BSA eased the membrane fouling.