Abstract

The bioremediation of petroleum hydrocarbon polluted water using Aspergillus niger and varying concentrations of sodium nitrate was investigated in this study. Five samples of petroleum hydrocarbon polluted water innoculated with A. nigercontaining 0.05, 0.1, 0.2, 0.3 and 0.4 M NaNO₃(aq) and the control was monitored for parameters such as Total Hydrocarbon Content (THC), Biological Oxygen Demand (BOD), pH and Turbidity over a period of forty nine days. The results obtained showed that the sample remediated with 0.4M NaNO₃ (aq) showed the greatest THC drop of 97.5% followed by 0.3M NaNO₃ (aq) with 97.1% drop, 0.2M NaNO₃ (aq) with 96.5% drop 0.1 M NaNO₃ (aq) with 95.8% and finally 0.05M NaNO₃ (aq) with 95.1% drop. The sample amended with 0.4M NaNO₃ (aq) showed the greatest BOD drop of 98.8% followed by 0.3 M NaNO₃ (aq) with drop of 98.5% then followed by 0.2 M NaNO₃ (aq) with drop of 98.4% then followed by 0.1M NaNO₃ (aq) with 98.3% drop. All four samples above fall within stipulated values of 30 mg/l by regulatory agencies like FEPA and DPR during the experimentation period. Bioremediation as a strategy for clean up of petroleum hydrocarbon polluted water has been shown to be efficient considering the level of drop in THC, pH, BOD and Turbidity which fall within the FEPA and DPR limits over the period of study. A. niger offer an efficient and interesting possibility of degrading petroleum hydrocarbon polluted water. 0.2, 0.3 and 0.4 M NaNO₃ (aq) are efficient in stimulating A. niger. Scale up of this bioremediation strategy is very promising and should be encouraged.

Key words: Bioremediation, crude oil polluted water, sodium nitrate, biochemical oxygen demand, total hydrocarbon content.