Investigation of the effects of factories effluents on the levels of selected heavy metals on modjo river, oromia regional state, Ethiopia

Abstract

This study was aimed to investigate the effect of factories effluents on the level of selected heavy metals on Modjo River Oromia Regional State, Ethiopia. Water samples were collected from the upstream and downstream of the river water and effluent samples emanating from different factories were collected from wastewater channel in June, 2018. Six heavy metals (Cd, Cr, Pb, Cu, Co and Zn) in industrial effluents and river water were analyzed by Graphite Furnace (GFAAS) in separate experiments. The concentrations of heavy metals in the effluents were compared with corresponding heavy metal values in the water. The obtained results indicated that the concentrations of Cr and Pb in all Modjo river water samples were above maximum permissible limit set by WHO, USEPA and ESA for drinking. On other hand, the concentrations of Cr, Zn, Pb and Cu metals in industrial effluents were above the maximum permissible limit set by WHO and USEPA that effluents should contain to discharge from the factories. But Cd was found below the method detection limit for both wastewater and water samples. Results of one way ANOVA tests (p ≤ 0.05) showed that presence of significant differences in the concentrations of heavy metals (expect for Cu) in among the various sampling stations of both factories effluents and water samples. Therefore, urgent measures needs to be taken to ameliorate the deteriorating nature of Modjo River and keep the water safe for domestic for downstream users.