Evaluation of DOC removal by advanced oxidation processes as pre-treatment of the biological process using low ozone doses

The presence of organic contaminants in raw water and high chlorine demand in drinking water treatment plants (DWTPs) in Ho Chi Minh City (HCMC) has contributed to the increased formation of disinfectant by-products (DBPs) in tap water. To address this issue, DWTPs require alternative methods to reduce the potential formation of DBPs and chlorine consumption. This study investigated the combination of various advanced oxidation processes (AOPs), including O3 only, O3-H2O2, and O3-UV, coupled with the biological activated carbon (BAC) process to remove the natural organic matter (NOM) as a precursor to DBPs. Batch-scale AOP experiments were conducted under different operating conditions, and the O3-UV process demonstrated the highest bDOC/DOC ratio, indicating the formation of biodegradable transformation products rather than mineralization. The integrated O3-UV-BAC process reduced DOC and UV254 by 40% and 52%, respectively. The empirical models showed that the O3-UV-BAC process significantly achieved high THMFP and HAAFP removals. Using ozonation or AOPs coupled with biological process to remove DBP precursors and organic micropollutants from the Saigon River water can be a potential method for ensuring a safe water supply system in HCMC.