ENVIRONMENTALLY HAZARDOUS HEAVY METALS AT MUNICIPAL SOLID WASTE DUMPING SITES IN HARAR CITY, HARARI REGIONAL STATE, ETHIOPIA

Abstract

The concentrations of heavy metals in municipal solid waste (MSW) reflect the amount of metals in products and are directly related to the amount of metals transferred to disposal sites. This study was conducted on MSW dumping sites at Selate and Kile sites in Harar City, Harari Regional State, Ethiopia to investigate the concentrations of some heavy metals in decomposed municipal solid waste and soil. From both dumping sites separately six decomposed waste sampling points were selected purposively to form two (a total of 2*2 = 4) composite samples and to investigate the concentration of heavy metals in soil at both dumping sites, three soil sampling points were purposively selected as fresh, intermediate and old waste dumping areas. Soil samples were collected from 0-20, and 20-40 cm depth using auger. A total of 6*2 = 12 soil samples were collected for both dumping sites separately. A composite soil samples were also collected from control areas near the dumping sites where wastes were not dumped separately from the depths. The heavy metals were analyzed using AAS. The results showed that the mean concentration were in the order of Zn>Mn>Cu>Fe>Pb>Co>Cd> Ni>Cr at Selate and Zn > Fe>Mn>Cu>Pb>Cd>Ni>Co>Cr at Kile. The pH values ranged from 8.17-8.19 and 7.78-8.18 for the soil from old and intermediate dumping sites respectively at Selate and it was also similar for the Kile site. Concentrations of the heavy metals were higher in soils from old and intermediate waste dumping areas at 0-20 cm and 20-40 cm depth. Concentrations of heavy metals in soil from dumping sites were higher than in soil from control sites. At both dumping sites concentration of heavy metals were below the acceptable range of deferent standards. pH of the soil was statistically correlated with most of heavy metals. Even though the concentrations of heavy metals were below the acceptable range, rule and regulation of waste treatment system and recycling of waste should be applied for sustainable use of the resources and environmental quality.