The Impacts of Solid Waste on Ground and Surface Water Quality in Kisii Municipality, Kenya.
Nyandwaro, Ernest Oyieko
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Leachate flow from urban municipal dumpsites into surface and ground water sources can be detrimental to the urban population who use these waters sources. Gradual accumulations of contaminants in the water sources can result into high loads of pollutants which are potentially toxic to the users. In Kisii Town River Nyakumisaro that drain through the town and improved ground water wells are the main sources of portable water for most residents. The major aim of the study was to determine the impact of municipal solid waste disposal on ground and surface water quality of these urban water sources. Specific objectives were to establish levels of pollutants in the wells and stream as compared to guidelines provided by KEBS for drinking water and NEMA standards for effluent discharge to portable water sources; to determine the effects of wet and dry seasons on wells and stream water pollution and to determine the correlation between levels of pollutants in the water sources with respect to the distance from the dumping site. Four wells were purposively sampled for the study during the dry and wet seasons (August, September and early October, 2015).Surface water samples were collected from the stream at depth of ≤ 30m at sampling points located 400m and 800m upstream and downstream. Water samples from the wells were directly collected from the improved Well taps. All samples were analyzed for physiochemical and biological pollution indicators. The physicochemical parameters investigated included: Temperature, pH, Electrical conductivity and anions No3- which were determined used using the standard analytical methods. Trace metals Pb, Cd, Zn and Mn were determined using Flame Atomic Absorption Spectrophotometer. Bacteriological analysis was done as prescribed by the standard methods for analysis of water and wastewater. The data obtained was analyzed using SPSS software. The levels of electrical conductivity (EC), Manganese (Mn), Zinc (Zn), Lead (Pb), Cadmium (Cd), NO3 - and E.coli in the leachate and portable water are higher than KEBS/NEMA standards indicating possible health impacts posed by the dumpsite on surface and ground water quality. In all standards the total coli.forms were found to be higher than 1600 counts/100ml posing a pathogenic health effect. The surface and ground water have pH within KEBS acceptable range for drinking water. The seasonal effect was manifested by increased pollutants levels during the wet seasons as compared to dry seasons that were attributed to the solubility of organic material and increased runoff to the stream and percolation during the wet season as compared to the dry period. The concentration of pollutants had negative correlation with distances from the dumpsite. Pollutants concentration levels downstream are least related between streams and well. Thus water flowing downstream had negative correlation both in Zn (r= -.677, P= .323) and Mn (r= -.655, P= .345). This could have been due to other factors like the industrial activity at the lower part of the dumpsite. The results depict need for periodic assessment of the water quality and enactment of law on the safe distances for establishing Wells from the dumpsite areas.