Characterization of wastewater from waste oil recovery plants and assessment of potential risks to human health

In this study, the chemical characterization of wastewater originating from waste oil recovery facilities was conducted; relationships among pollutants were evaluated, and the potential health risks of treated and untreated wastewater were analyzed. Average concentrations in wastewater analyses were determined as follows: ammonium 367 mg/L, suspended solids 361 mg/L, hydrocarbons 24,252 mg/L, oil and grease 26,736 mg/L, copper 0.51 mg/L, lead 0.088 mg/L, and cyanide 914 mg/L. Correlation analyses revealed a very strong relationship between hydrocarbons and oil-grease (r(2) = 1.0), indicating these parameters likely originate from similar sources. High correlations were also observed between hydrocarbons and copper (r(2) = 0.972), suspended solids (r(2) = 0.944), and iron (r(2) = 0.865). Health risk assessments for treated wastewater showed no significant risk for either carcinogenic or non-carcinogenic effects. However, calculations for untreated wastewater indicated hazard indices (HI) suggesting a potential health risk under certain conditions. Overall, the findings suggest that risks posed by cyanide and certain heavy metals may be low, although further advanced toxicological and epidemiological studies are needed to confirm this. Additionally, comprehensive monitoring programs are necessary to understand the long-term environmental and public health impacts.