Analysis of microbiological and physiochemical properties of top soil from municipal dumpsites in Benin City

Abstract

The effect of disposing municipal waste on soil was evaluated by analyzing the microbiological and enzyme activity of soil samples at three different locations, from five municipal waste dumpsites and compared with soil samples from a farmland which serves as the control. Soil microbial load, physicochemical parameters and enzyme activities were determined using standard procedure. The highest heterotrophic bacterial count (1.02 ± 0.4 × 10⁷ cfu/g) was recorded from New Benin market Dumpsite (sampling point A) while the least (3.25 ± 0.4 ×10⁴
cfu/g) was from the control (sampling point C). The result obtained showed that there was significant difference (p> 0.05) in the Heterotrophic bacteria and fungi count between the control and the soil samples from the various locations of the dumpsites. The bacteria identified were Acinetobacter species, Micrococcus luetus, Pseudomonas aeruginosa, Serratia species, Bacillus subtilis, Klebsiella species, Staphylococcus aureus, Arthrobacter species, Escherichia coli and Streptococcus feacalis, while fungi identified were Aspergillus niger, Trichoderma species, Penicillium species, Fusarium species, Mucor species, Saccharomyces species, Rhizopus species. Pseudomonas aeruginosa was the most prevalent bacterial isolate (20.3 %) while Streptococcus feacalis was the least isolate (3.1 %). Aspergillus niger was the most prevalent fungi isolate and Fusarium species the least isolated fungi. The enzymatic profile revealed that Oba market and Satana market had the highest Dehydrogenase and Urease activities with the values of 23.70 ± 16.32 mg/g/6h and 97.90 ± 14.93 mg/g/24h respectively. The physicochemical parameter measured in this study showed that the soil samples were acidic (5.60 ± 0.17 – 6.23 ± 0.35) and sandy (72.20 ± 4.11 - 90.60 ± 0.00 %). Trace amount of zinc (0.10 ± 0.00 – 1.53 ± 1.02 mg/kg), lead (< 0.01 – 1.23 ± 0.17 mg/kg) and copper (0.01 ± 0.00 – 0.80 ± 0.10 mg/kg) was observed in both the control soil and the test samples. The result showed that although municipal waste dump is an unsustainable practice, it has a positive impact on the quality of the soil samples examined.

Keywords: Microbiological, Enzymatic, Municipal Waste Dumpsites, Soil, Benin City