Determination of Catechol Toxicity Changes Before and After the Ctalytic Ozonation Process Using Bioassay Method

Catechol is one of the most common compounds in the industrial wastewater including oil and petrochemical, pesticides industries. The drainage of these industries leads to aquatic organisms poisoning and adverse effects on the environment. Therefore, this study aimed to evaluate the effects of catechol toxicity changes before and after the catalytic ozonation process by Daphnia Magna bioassay. This study is an applied research in which the toxicity of catechol and its products from degradation was evaluated by bioassay method during the Catalytic ozonation process. First stock solution was prepared at concentration of 250 mg/l followed by preparation of 10 samples that each contained 0 (control), 0.5, 1, 3, 6, 12, 25, 50, 75 and 100% of volume of primary solution. Initial samples were prepared from reactor effluent in the same volume. Based on the standard method, 10 Daphnia infants were added to prepared samples. Samples were evaluated after 24, 48, 72 and 96 hours. Finally, lethal concentration (LC50) and toxic units (TU) were calculated using probit analysis. According to the results, LC50 (24 hours) of raw effluent with an initial concentration of 250 mg / L of catechol increased from 13.30 ml/100 ml to 33.9 ml/100 ml after 60 minutes treatment. Consequently, the toxicity unit decreased from 7.51 TU to 0.9 TU which means that the toxicity dropped by 88%. Finally, the toxicity of treated effluent decreased during catalytic ozonation process to degradation of catechol. Bioassay is a simple and effective way to evaluate the toxicity potential of Catechol to discharge it to surface water. Based on the bioassay by Daphnia Magna, Catalytic ozonation process is able to reduce the toxicity of catechol by degradation this compound and breaking into other products.