OH degraded 2-Methylisoborneol during the removal of algae-laden water in a drinking water treatment system: Comparison with ClO2.

ABSTRACT

The growth of algae in water and the taste and odour compounds produced by algal metabolism present a threat to water quality, public health and aquatic ecosystems and cannot be effectively removed by conventional water treatment processes. In this paper, a hydroxyl radical (OH)-based drinking water treatment system (DWTS) with a capacity of 480 m3 per day was built in the Xinglin water plant, Xiamen, China. With pretreatment at 0.88 mg L-1, sand filtration, and disinfection at 0.31 mg L-1 during the conveyance of algae-laden water within only 9.8 s, OH removed all five kinds of algae, with a total content of 35,180 cells mL-1, while ClO2 treatment left live and dead algae at 7150 cells mL-1, which would be transported into the pipe networks for the drinking water supply. Meanwhile, OH degraded 2-Methylisoborneol (2-MIB) from 175 to 4.4 ng L-1, which was below the Chinese standard of 10 ng L-1, while ClO2 degraded 2-MIB only to 155 ng L-1. Based on analyses of the mass spectra database, OH could mineralize 2-MIB by opening the ring structures of 2,2-dimethyl-1,3-cyclopentanedione and 2-methyl-cyclohexenecarboxaldehyde to produce small-molecule compounds. After OH pretreatment and OH disinfection, all water quality and disinfection by-product indexes met the Chinese Sanitary Standards for Drinking Water. Therefore, OH advanced oxidation produced using strong ionization discharge could be practically applied for the degradation of 2-MIB during the treatment of algae-laden water in the OH DWTS.