Evaluating The Performance of Indigenous Microorganism for Bioremediation of Lead Contaminated Soil
Abstract
This work is on remediation of lead concentration (130.36 mg/kg) in soils from farm settlement at Agbabu community in Ondo State of Nigeria to below maximum allowable 100 mg/kg specified for safe agriculture by standards to ensure that farm products from this farm settlement close to area of mining are safe for human beings. Three indigenous organisms: Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Proteus mirabilis (P. mirabilis) were engaged for the remediation study. The organisms were isolated and cultured. Optimum weights of the distinct organisms were inoculated in 5g soils each conditioned with optimum values of pH, temperature, stirring frequency and nutrient in thirty-six 50 ml beakers; and experimented for residual lead ion at times 5, 10, 15, 20, 25, 30 and 35 days in triplicate with Atomic Absorption Spectrophotometer. Lead concentration in the soil was tackled by the three organisms, they were able to bring the initial concentration of lead to below the maximum allowable concentration, but this happened at different rates and efficiencies. For the three organisms, there was a continuous decline in the soil lead concentration with time. B. subtilis was able to bring the concentration to below the maximum allowable concentration at time 10 days with efficiency of 27.64% at a residual concentration of 94.32 mg/kg. In contrast, P. mirabilis and E. coli were able to bring the initial concentration to below the maximum allowable concentration at time 15 days with different efficiencies of 32.64 % at 87.81 mg/kg residual concentration for P. mirabilis and 34.30 % at 85.85 mg/kg residual concentration for E. coli. The initial strength rating showed B. subtilis to be ahead in strength, seconded by E. coli while P. mirabilis lagged behind them. This was noticed from time 5 days to 15 days. However, after this time, P. mirabilis was observed to take the lead, seconded by B. subtilis while E. coli lagged behind them. This is obviously remarkable in their 35 days removal efficiencies of 75.12% for P. mirabilis at a residual concentration of 32.44 mg/kg; 74.26 % for B. subtilis at a residual concentration of 33.55 mg/kg; and 52.26 % for E. coli at a residual concentration of 62.24 mg/kg. This shows that removal by B. subtilis is preferred on a short-run bioremediation, while removal by P. mirabilis is preferred on a long-run pollution control.
Keywords
Remediation, Indigenous Organisms, Lead Concentration, Pollution Control
Supporting Institution
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Project Number
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Ethical Statement
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Thanks
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