Enhanced Coagulation for Removal of Dissolved Organic Matter and Trihalomethane Formation Potential from Raw Water Supply in Sri-Trang Reservoir, Thailand

Abstract

The present research aims to examine the coagulation process enhancement for dissolved organic matter (DOM) and The present research aims to examine the coagulation process enhancement for dissolved organic matter (DOM) and trihalomethane formatation potential (THMFP) removal from a raw water supply with low turbidity and specific ultraviolet absorption (SUVA). Coagulation conditions were optimized using polyaluminum chloride (PACl), PACl with dry cationic polymer (polymer), and PACl with polymer and powder activated carbon (PAC). DOM was measured in terms of dissolved organic carbon (DOC) and ultraviolet absorption at a wavelength of 254 nm (UV-254). Results show that the optimal condition for PACl, PACl and polymer, and PACl with polymer and PAC coagulation were PACl 20 mg/L at pH 7, PACl 20 mg/L and polymer 0·1 mg/L, and PACl 20 mg/L with polymer 0·1 mg/L and PAC 10 mg/L, respectively. When the DOM contents in coagulated water were fractioned to be hydrophilic (HPI) and hydrophobic (HPO) groups, it was found that the coagulation process could effectively remove more DOC of HPO than DOC of HPI. The coagulation using PACl combined with polymer and PAC provided the highest level of DOC of HPI, DOC of HPO, Trihalomethane formation potential (THMFP) of HPI, and THMFP of HPO removal efficiencies and were shown to be 65%, 75%, 77%, and 79%, respectively.