Pilot study on pre-ozonation enhanced drinking water treatment process

摘要

The enhancement of TOC, CODMn, 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, CODMn 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 CODMn 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 CODMn to a significant degree, suggesting that the CODMn 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.