title: Fatty acid fouling of forward osmosis membrane: Effects of pH, calcium, membrane orientation, initial permeate flux and foulant composition.
abstract: 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 0.5hr at unadjusted pH3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated pH 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. 0.5mmol/L Ca(2+), active layer facing draw solution (AL-DS) and 1.5mol/L NaCl (DS); 2. No Ca(2+), active layer-facing FS (AL-FS) and 4mol/L NaCl (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 pH3.56, and larger than the two values at pH9.00. This manifested that, at pH3.56, BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at pH9.00, the mutual effects of OA and BSA eased the membrane fouling.
authors: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Pin
authors: P
authors: Zhao
authors: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Baoyu
authors: B
authors: Gao
authors: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China. Electronic address: qyyue58@aliyun.com.
authors: Qinyan
authors: Q
authors: Yue
authors: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Pan
authors: P
authors: Liu
authors: School of Civil and Environmental Engineering, University of Technology, Sydney, Broadway, NSW 2007, Australia.
authors: Ho Kyong
authors: HK
authors: Shon
mesh_terms: D057219:Biofouling; D002118:Calcium; D005227:Fatty Acids / Q000032:analysis*; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D009995:Osmosis; D012965:Sodium Chloride; D014873:Water Pollutants / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D005227:Fatty Acids; D008567:Membranes, Artificial; D014873:Water Pollutants; D012965:Sodium Chloride; D002118:Calcium
keywords: Forward osmosis; Membrane fouling; Octanoic acid; Reverse solute flux; Water flux