Pilot Study on Pre-Ozonation Enhanced Drinking Water Treatment Process

摘要

The enhancement of TOC,COD_(Mn),and UV254 reduction in the conventional drinking water treatment process by pre-ozonation was investigated in South China on treating dam source water with a pilot plant consisting of pre-ozonation,coagulation-sedimentation,and filtration units.Pre-ozonation enhanced the reduction of NOM in the conventional coagulation-sedimentation and filtration process,and the total removals of UV254,COD_(Mn_ and TOC were improved for 34.6%,18.1% and 15.3%,respectively by the adoption of pre-ozonation under an ozone dose (in ozone consumption base) of 0.85 mg/L.The enhancement of UV254 and COD_(Mn) removals was mainly achieved through direct ozonation on humic substances,and that for TOC removal was achieved through biodegradation in sand filtration.In comparison with the TOC removal of 38%,a removal of 49% was acquired for SDS-THM under a pre-ozonation dose of 0.80 mg/L,indicating the selective removal of THMFP.The reduction of SDS-THM paralleled the reduction of COD_(Mn) to a significant degree,suggesting that the COD_(Mn) might be an effective surrogate parameter for SDS-THM if the raw water does not contain the reductive inorganic matters.Although the source water contains 13.2-27.0 mu g/L bromide,the formation of bromate was negligible when the ozone dose was below 1.0 mg/L.