The Impacts Of Dumpsite And Domestic Waste Leachate On Groundwater Quality In Kilifi Town, Kilifi County, Kenya

ABSTRACT

Kilifi town (study area) is in Kilifi County, Kenya. Groundwater samples were collected from wells which were close (≤30m) from pit latrines and (≤2.5Km) from refuse dumpsite. Ten wells, namely wells number (1- 10) were purposively sampled during wet season (July, August and September, 2011) and also during dry season (January, February and March, 2012), with the aim of assessing the physicochemical and biological impacts of the leachate from the dumpsite and the pit latrines on quality of groundwater in Kilifi town and its environs. The physico-chemical parameters investigated included: Temperature, pH, Electrical conductivity and anions So42- and No3- which were determined using the standard analytical methods. Trace metals Pb, Cd 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 Matlab software. The levels of electrical conductivity (E.C), Manganese (Mn), Cadmium (Cd), No3-, and E.coli found in Kilifi town are higher than KEBS health based guideline values thus indicating possible impacts of the dumpsite and pit latrines on groundwater quality. The measurements of the parameters were as follows: E.C values ranged from 343- 4237 microS/cm against recommended guideline of 120 microS/cm. Cd ranged from 0.02- 0.03 mg/L against guideline of 0.005mg/l. Mn ranged from 0.09- 0.34 mg/L against the guideline of 0.1 mg/L and 9 out of the 10 wells recorded higher values than the guideline. NO3- ranged from 7- 40 mg/L against guideline of 1mg/L and 8 out of the 10 wells recorded higher values than the guideline. The total coli.forms ranged from 180- 18630 counts/100ml against the guideline of 0 counts/100ml and all the sampled wells registered higher values than the guideline. The results affirm groundwater pollution and indicate possibilities of toxicities of these pollutants and their threat to human health. The groundwater had PH within the KEBS acceptable range for drinking water. The seasonal effect was manifested in that, the levels of pollutants increased in wet seasons as compared to dry seasons. This could have been caused by the increased percolation during the wet season. The concentration of Escherichia coli.forms in groundwater wells had strong negative correlation with distances from the dumpsite and the pit latrines with r values ≥ - 0.5. Wells 1, 2, 3 and 4 were less than 15m from the nearest pit latrines. Out of these, wells number 1, 2 and 4 recorded higher counts of coli.forms compared to the rest due their proximity to pit latrines. Well number 3 recorded less coli.forms despite being equally closer to pit latrines. This could have been due to other factors like lining of the pit. The results confirm the need for determining safe distances between wells and waste disposal sites to abate groundwater pollution.