Removal of organics and control of bromate for a southern china water supply

Abstract

A pilot plant with successive preozonation, coagulation-sedimentation, sand filtration, postozonation, and biological activated carbon was operated for more than six months to treat reservoir water containing 15-38 µg/L of bromide in southern China. Preozonation enhanced the removal of chemical oxygen demand using potassium permanganate as the oxidant (COD Mn ) and ultraviolet light absorbance at 254 nm (UV 254 ) using coagulationsedimentation but did not improve total organic carbon (TOC)-removal effectively. However, preozonation markedly enhanced the removal of trihalomethane formation potential (THMFP) by the conventional process, and THMFP removal by the combination of preozonation and conventional treatment was 57% using an ozone dose of 0.8 mg/L. Almost no bromate formed during preozonation. An ozone dose of 2.0 mg/L (0.5 mg/L and 1.5 mg/L for pre-and postozonation, respectively) was found to be the optimal dosage for the maximum removal of organics (65% of THMFP, 52% of TOC, 63% of COD Mn , and 84% of UV 254 ) while keeping bromate under 5 µg/L. A combination of conventional treatment with preozonation should be a suitable alternative if the primary goal is to remove THMFP.

Development and application of innovative technologies for drinking water quality assurance in China

“…These programs focused on the application conditions of ozone and activated carbon, stressing on the control of bromate during ozonation. Figure 8 shows the pilot experimental setup used for advanced treatment study in Shenzhen [46][47][48]. The control of bromate formation during ozonation was first studied in this program.…”

“…From the tenth Five-Year National Plan (2001)(2002)(2003)(2004)(2005), China has started several big projects concerning drinking water safety, which for the first time included research on preozonation. Preozonation on a bromide-bearing reservoir source water in south China at ozone doses of 0.5-1.0 mg/L (at ozone consumption base) was found to enhance the removals of trihalomethane formation potentials (THMFP) and haloacetic acid formation potentials (HAAFP) by conventional treatment significantly without formation of bromate [46][47][48]. Except for the selective enhancement of the DBPFPs removal, preozonation at an ozone dose of 0.2 mg/L was also found to be very effective in decreasing turbidity and particle number of the filtrate and prolonging the filtration duration.…”

Control of corrosive water in advanced water treatment plant by manipulating calcium carbonate precipitation potential

“…The AWTP by a BAC filtration process can reduce the concentration of dissolved organic carbon (DOC) in raw water more than a general water treatment process without the BAC procedure [22][23][24]. The film formed on the inner surface of water pipes by natural organic matter (NOM) included in the DOC components plays some role in corrosion prevention [25].…”