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

Abstract Ozone-based advanced oxidation processes (AOPs) have emerged as promising technologies for water treatment. Recent studies have shown that ozone microbubbles can enhance ozone mass transfer during water treatment, and combining microbubble ozonation with pre-treatment steps can improve the removal of micropollutants from source water. This study evaluated the removal of atrazine from natural water using three different combined processes (chlorine/KMnO4/PAC pre-treatment followed by ozonation). The results indicate that all three combined processes achieved higher atrazine removal rates than pre-treatment alone or ozonation alone. The atrazine removal rate was highest at alkaline pH values, and all three combined processes were affected by oxidant dose and pH. The combination of chlorine pre-treatment with ozonation was the most effective for natural source water, with a removal rate of 59.7% that exceeded the sum of the individual treatments. However, this combined process was affected by water quality, particularly the nature of organic matter, and a relatively high concentration of ammonia nitrogen (greater than 0.5 mg/L) negatively impacted on treatment outcomes. This study highlights the potential for utilizing ozone micro/nanobubbles to enhance ozone mass transfer and provides valuable insights for optimizing the combined application of pre-treatment and ozonation to remove atrazine from natural water sources efficiently.