Reduction of Biocide-Polluted Wastewater Using O3 and H2O2/O3 Oxidation Processes

The objective of the presented study was to test various oxidation processes with the aim being to reduce the concentration and toxicity of biocide wastewater from a Slovenian phytopharmaceutical factory. Laboratory-scale experiments employing two AOP processes - ozonation (O3) and peroxone (H2O2/O3) - were applied to reduce the concentration of the active components involved, i.e., methylisothiazolone (MI), chloromethylisothiazolone (CMI) and dichloromethylisothiazolone (DCMI). The reduction of the biocide wastewater load for the performed oxidation processes was evaluated using ecological parameters. The H2O2/O3 oxidation procedure using an O3 flow rate of 1g/L h, at a pH value of 10 and with the addition of 5 ml of H2O2 (0.3 M) proved to be the most effective treatment. The toxicity of the biocide-load wastewater with an initial EC50 = 0.38%, decreased to EC50 (24h) 100% and EC50 (48h) = 76%.