Effect of Palm Kernel Oil Processing Effluents on the Soil’s Microbial Community

Abstract

Palm kernel oil is processed in Nigeria in small scale mills and the effluents are disposed of untreated into the surrounding soil, therefore the effect of such disposal to the soil’s microbial population was determined in this study. Palm kernel oil mill processing effluents (treated and untreated), effluent-polluted soil (treated and untreated) as well as the unpolluted soil (control) were analysed microbiologically. The total bacterial counts, total coliform counts and the total fungal counts of the samples were determined using standard analytical methods. The total bacterial counts (15.2x104 CFU/mL) and total coliform counts (3.4x104 CFU/mL) of the untreated effluent-polluted soil were higher than those of the other samples including the unpolluted soil. However, the unpolluted soil had the highest fungal count of 2.5x104 CFU/mL, indicating that the palm kernel oil mill processing effluents (treated and untreated) had significant negative effect on the fungal population of the soil. The microorganisms isolated from the effluents and soil samples were Bacillus spp, Micrococcus spp, Pseudomonas spp, Staphylococcus spp, Escherichia spp, Klebsiella spp, Serratia spp, Salmonella spp, Aspergillus spp, Rhizopus spp, Cladosporium spp, Penicillium spp, Fusarium spp, Mucor spp, Candida spp and Saccharomyces spp. The effluents may have had toxic constituents that reduced the fungal populations of the polluted soils. Palm kernel oil mill processing effluents must therefore be adequately treated before its discharge into the soil environment.