Assessment of microbial population and physico-chemical properties of abattoir effluent-contaminated soils in Benin City, Nigeria

Abstract

The research was conducted in order to determine the effect of abattoir effluent on the microbiological and physico-chemical characteristics of the receiving soils in Ikpoba Hill and Oluku located in Benin City, Nigeria. Microbial analysis was carried out using standard microbiological techniques. The microorganisms isolated from the contaminated soil in this study were: Escherichia coli, Pseudomonas aeruginosa, Bacillus sp, Staphylococcus. epidermidis, Staphylococcus aureus, Alcaligenes sp, Klebsiella sp, Aspergillus flavus, Aspergillus niger, Penicillium sp, Geotrichum sp and Mucor sp. The results revealed high count of 4.77 x 10⁶ ± 0.001 cfu/g, 7.31 x 10⁴ ± 0.01 cfu/g and 2.53 x 10³ ± 0.001 cfu/g for bacteria, coliform and fungal count, respectively in Oluku abattoir effluent-contaminated soil, while Ikpoba Hill effluent-contaminated soil had 6.64 x 10⁶ ± 0.001 cfu/g, 6.68 x 10⁴ ± 0.001 cfu/g and 3.47 x 10³ ± 0.001 cfu/g for bacteria, coliform and fungal count, respectively. The microbial counts were higher in the contaminated samples than in the control, having 2.35 x 10⁴ ± 0.1 cfu/g, 1.15 x 10² ± 0.1 cfu/g and 1.25 x 10³ ± 0.1 cfu/g for bacteria, coliform and fungal counts, respectively. The physico-chemical parameters showed that the contaminated soil had pH of 7.70 and 7.80, total organic Carbon of 30.66 ppm and 33.33 ppm, Potassium of 8.84 ppm and 8.90 ppm, Phosphorus of 7.10 ppm and 7.45 ppm, Nitrogen of 0.39 ppm and 0.40 ppm for Oluku and Ikpoba hill abattoirs, respectively. The presence of the coliform organisms is an indication of recent faecal contamination of the abattoir effluent, which can cause significant environmental and health hazard. Overall, the observed high level of microbial contamination of the soils suggests that they are not just contaminated but possibly polluted, and this situation could lead to transmission of pathogens to humans.

Keywords: Effluent, abattoir, bacteria, fungi, health risk