The effect of pre-treatments on atrazine removal from source water by microbubble ozonation.

Ozone-based advanced oxidation processes (AOPs) have emerged a promising avenue for water treatment, offering effective removal of micropollutants. Recent research underscores the potential of ozone microbubbles to enhance ozone mass transfer during water treatment, particularly when combined with pre-treatment steps. This study aimed to evaluate the efficacy of three different combined processes (chlorine/KMnO/PAC pre-treatment followed by ozonation) in removing atrazine, a common micropollutant from natural source water. Results revealed that all combined processes achieved higher atrazine removal rates compared to individual pre-treatment or ozonation methods. Notably, the highest atrazine removal rates were observed under alkaline pH conditions, with treatment outcomes influenced by oxidant dose and pH levels. Among the combined processes, chlorine pre-treatment followed by ozonation emerged as the most effective approach, achieving a removal rate of 59.7% that exceeded the sum of individual treatments. However, this treatment efficacy was affected by water quality parameters, particularly the presence of organic matter and elevated ammonia nitrogen concentration (> 0.5 mg/L). This study highlights the potential for utilizing ozone micro/nanobubbles to enhance ozone mass transfer and offers valuable insights for optimizing the combined application of pre-treatment and ozonation strategies for efficient atrazine removal from natural water sources.