Comparison of epichlorohydrin–dimethylamine with other cationic organic polymers as coagulation aids of polyferric chloride in coagulation–ultrafiltration process

Abstract

Epichlorohydrin–dimethylamine (DAM–ECH) copolymer was acquired by polycondensation of hazardous reagents: epichlorohydrin (analytical reagent, A.R.) and dimethylamine (A.R.) with ethanediamine (A.R.) as cross-linker. Its coagulation and membrane performance as coagulation aid of polyferric chloride (PFC) was evaluated by comparing with other two cationic coagulation aids: poly dimethyl diallyl ammonium chloride (PDMDAAC) and polyacrylamide (PAM) in humic acid–kaolin (HA–Kaolin) simulated water treatment. Firstly, optimum dosages of PFC&DAM–ECH, PFC&PDMDAAC and PFC&PAM were identified according to their coagulation performance. Then their impacts (under optimum dosages) on membrane fouling of regenerated cellulose (RC) ultra-membrane disc in coagulation–ultrafiltration (C–UF) process were reviewed. Results revealed that small addition of DAM–ECH was the effective on turbidity and DOC removal polymer. Furthermore, in the following ultra-filtration process, external membrane fouling resistance was demonstrated to be the dominant portion of the total membrane fouling resistance under all circumstances. Meanwhile, the internal membrane fouling resistance was determined by residual of micro-particles11Micro-particles: Humic acid molecules, Kaolin and micro-floc formed in coagulation process that cannot be intercepted by cake layer or ultrafiltration membrane. that cannot be intercepted by cake layer or ultrafiltration membrane.