evaluating the removal of crude oil toxicity components in drinking water by ozonation process

background: crude oil is a very complex composition with harmful effects in human health such as carcinogenesis and blood effects. using the bioassay method to assess the effect of purification process produces useful results. in this study the effect of ozonation to reduce the toxicity of crude oil in the water is investigated. methods: standard sample of the water soluble fraction were prepared with one part of crude oil and 9 part of water. for toxicity assessment, different concentrations of water soluble fraction of crude oil and larvae of rainbow trout were used. before and after ozonation, toc and the bioassay tests were performed. findings: ozonation is effective in reducing the toxicity of the crude oil in drinking water. by increasing the time of bioassay experiment, the toxicity is increased too. lc 50%, 98 hours of the sample toc was 60 and 54.98 mg/l before the ozonation process and after that in 1 and 10 mg/l, lc 50%, 98 hours was increased to 113.3 and 205.5 mg/l and the toc reached to 42.8 and 205.5 mg/l. conclusion: increasing the ozone doses to reduce the toxicity was highly effective, but intensity of toc removal was not the same as the toxicity removal.  in order to investigate the effectiveness of one treatment process to remove special pollutants, using bioassay test could produce useful and valuable results.