Control of Algae-Induced Disinfection By-Products Formation by Pre-Oxidation for Typical Algal Species in Drinking Water Treatment Plants of Chongqing, China.

Severe eutrophication and frequent algal blooms in source waters (the main stream of the Yangtze River, the Jialing River tributary, and the Three Gorges Reservoir area) pose significant challenges to water treatment plants (WTPs) in Chongqing Municipality, China. This leads to reduced efficiency of conventional treatment and elevated disinfection by-products formation potential (DBPs-FP) in high algae-laden water. This study systematically evaluated the algae removal efficacy of pre-oxidation using potassium permanganate (KMnO4) and ozone (O3), alongside their control effects on algae-derived DBPs-FP, targeting two typical bloom-forming species: the typical cyanobacteria, i.e., M. aeruginosa and the typical diatom, i.e., Synedra sp. Results demonstrated that both low-dose O3 and micro-acidified low-dose KMnO4 effectively inactivated both algal species. Based on pre-treatment efficacy, targeted integrated control processes compatible with existing Chongqing WTP infrastructure were proposed. The combination of micro-acidified low-dose KMnO4-powdered activated carbon (PAC)-conventional water treatment process was effective in controlling M. aeruginosa-derived DBPs. Conversely, the integrated sequence of low-dose O3 pre-oxidation-conventional treatment-O3-Biological Activated Carbon (BAC) was highly effective for controlling Synedra sp.-derived DBPs. This research provides crucial technical support and a parametric basis for optimizing treatment processes in Chongqing WTPs handling high algae-laden source waters, specifically for mitigating algae-derived disinfection by-products.