title: Forward osmosis filtration for removal of organic foulants: Effects of combined tannic and alginic acids.
abstract: The filtration performance of combined organic foulants by forward osmosis (FO) in active-layer-facing-the-draw-solution (AL-facing-DS) orientation was investigated systematically. Tannic acid and alginate were used as model organic foulants for polysaccharides and humic dissolved organic matters, respectively. The FO could reject combined and single tannic acid and alginate foulants effectively. The more severe fouling flux decline, accompanied with lower combined foulants' retention, was observed with increasing proportions of tannic acid in the combined foulants-containing feed, which was ascribed mainly to the more severe fouling resulting from tannic acid adsorption within the porous support layer of the FO membrane compared to minor alginate deposition on the membrane surface. It was found that the higher the initial flux level and cross flow velocity, the faster the flux decline with lower mixed foulants retention. It was also revealed that the calcium ions in a basic solution enhanced the combined fouling flux reduction and combined foulants retention. As the major constituent of the combined fouling layer, the adsorption of tannic acid might play a more significant role in the mixed fouling of the FO membrane, which was probably influenced by permeation drag caused by water flux and chemical interactions induced by feed solution pH and calcium ion concentration.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Yangtze Water Environment of Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Yangtze Water Environment of Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Wanzhu
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Yangtze Water Environment of Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: chuhuaqiang@tongji.edu.cn.
authors.forename: Huaqiang
authors.initials: H
authors.lastname: Chu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Key Laboratory of Yangtze Water Environment of Ministry of Education, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Bingzhi
authors.initials: B
authors.lastname: Dong
mesh_terms: D000327:Adsorption; D000464:Alginates / Q000737:chemistry*; D005374:Filtration / Q000295:instrumentation / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D057446:Hydrodynamics; D008567:Membranes, Artificial; D009995:Osmosis; D012996:Solutions; D013634:Tannins / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D008567:Membranes, Artificial; D012996:Solutions; D013634:Tannins; D020723:Glucuronic Acid
keywords: Alginate; Forward osmosis; Fouling; Internal concentration polarization (ICP); Tannic acid