Abstract

Physico-chemical and microbiological parameters were analyzed in leachate and groundwater samples  obtained at different locations adjacent to a municipal solid waste landfill in order to assess the impact of leachate percolation on groundwater quality. Total dissolved solids (TDS), electrical conductivity (EC), and Na⁺ exceeded the World Health Organization (WHO) tolerance levels for drinking water in 62.5, 100, and 37.5% of the groundwater samples, respectively with pH and Fe exceeding WHO limits in 75% of the samples. Significant negative correlations of -0.839, -0.590, and -0.590 were shown by Na⁺, TDS, and EC respectively to distance from landfill. A high population of Enterobacteriaceae ranging from 4.0 × 10³ ± 0 to 1.0575 × 10⁶   ± 162,705 CFU/ml was also detected in the groundwater samples, indicating contamination. The results show that the leachate from the landfill has a minimal impact on the groundwater resource and this can be attributed to the existing soil stratigraphy at the site consisting of clay which is deduced to have a significant influence on the natural attenuation of leachate into groundwater.

Key words: Groundwater, correlation, percolation, landfill, leachate, municipal solid waste, natural attenuation, Enterobacteriaceae