title: Pre-treatment for ultrafiltration: effect of pre-chlorination on membrane fouling.
abstract: Microbial effects are believed to be a major contributor to membrane fouling in drinking water treatment. Sodium hypochlorite (NaClO) is commonly applied in membrane cleaning, but its potential use as a pretreatment for controlling operational fouling has received little attention. In this study, the effect of adding a continuous low dose of NaClO (1 mg/l as active Cl) in combination with alum, before ultrafiltration, was compared with only alum as pretreatment. The results showed that the addition of NaClO substantially reduced membrane fouling both in terms of the rate of TMP development and the properties of the membrane cake layer. Although the size of nano-scale primary coagulant flocs changed little by the addition of NaClO, the cake layer on the membrane had a greater porosity and a substantially reduced thickness. NaClO was found to inactivate bacteria in the influent flow, which reduced both microbial proliferation and the production of proteins and polysaccharides in the cake layer and contributed significantly to improving the overall ultrafiltration performance. NaClO dosing had no adverse impact on the formation of currently regulated disinfection by-product compounds (THMs and HAAs).
authors.affiliation: 1] Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China [2] Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Wenzheng
authors.initials: W
authors.lastname: Yu
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Graham
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jiuhui
authors.initials: J
authors.lastname: Qu
mesh_terms: D000534:Alum Compounds; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D057219:Biofouling / Q000517:prevention & control*; D004202:Disinfectants / Q000494:pharmacology*; D005434:Flow Cytometry; D054879:Halogenation; D008567:Membranes, Artificial; D011108:Polymers / Q000737:chemistry; D016062:Porosity; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013853:Thioacetamide / Q000737:chemistry; D022882:Trihalomethanes / Q000737:chemistry; D014462:Ultrafiltration / Q000379:methods*
chemical_list: D000534:Alum Compounds; D004202:Disinfectants; D008567:Membranes, Artificial; D011108:Polymers; D022882:Trihalomethanes; D013853:Thioacetamide; C041524:aluminum sulfate; D012973:Sodium Hypochlorite