Toxic Effect of Refinery Industrial Effluent Using Three Toxicity Bioassays

Abstract

Aims: To determine the toxic effect of refinery industrial effluents using three toxicity bioassays. Study Design: Five treatments and the controls designs were set up in triplicates containing 6.25%,12.5%, 25%, 50%, 100% and 0% of the industrial effluents and incubated at 24°C for 0 - 96 h. The five treatments and control set ups designated as PH, Warri and Control (Without effluent) were used to determine the toxic effect of industrial effluents. Place and Duration of Study: Department of Microbiology, Faculty of Natural Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2019 and December, 2019. Methodology: A laboratory scale study was carried on two composite samples of the produced water samples from the two studied areas using physicochemical analyses, microalgal toxicity test, mollusk toxicity and Zea mays test. Results: The results revealed that Port Harcourt refinery effluent contains higher quantities of physicochemical parameters than the Warri effluent sample. Warri sample had the most harmful effects on Selenastrum capricornutum, Lymnaea stagnalis and Zea mays, with ErC50 values of 47.62%, LC50 of 51.86% and EC50 of-32.68%, respectively. Inhibition (%) and mortality (%) of all species used were found to be concentration dependent with a significant (P < 0.05) strong positive correlation at increasing concentrations of industrial effluents. Conclusion: Thus, these raw industrial effluents from Port Harcourt and Warri refineries are toxic and induced growth inhibition, mortality and phytotoxicity and adequate measures should be taken by these industries to minimize their negative environmental impacts.