Biodegradation of used lubricating engine oil contaminated water using indigenous hydrocarbon degrading microbes in a fixed bed bioreactor system

The performance of a mixed population of hydrocarbon-degrading microbes in removing hydro-carbon contaminant in water was investigated using a fixed bed bioreactor system. The hydrocarbon-degrading microbes used for the study were isolated from oil-contaminated soil and further cultured in a nutrient medium. Sample concentrations of 500 mg/L, 1000 mg/L, 2000 mg/L and 6000 mg/L were studied. Each sample concentration was studied at loading rates of 0.5 L/min, 1.0 L/min, and 2.0 L/min for a week. Total petroleum hydrocarbon (TPH), pH, temperature, dissolved oxygen (DO), conductivity and the microbial population density were measured to ascertain the progress of microbial degradation of the oil contaminant in the water. A minimum degradation rate of 36. 83 ± 0.00% was achieved at the least administered loading rate of 0.5 L/min at 1000 mg/L oil concentration. Maximum degradation rate of 93.85 ± 0.00% was also achieved at loading rate of 1.0 L/min at the highest oil concentration of 6000 mg/L. The minimum and maximum degradation rates were achieved at microbial populations of 1. 53E + 13 ± 0.00 and 1.50E+13 ± 0.00, respectively. The hydrocarbon degradation occurred in an optimum pH range of 6.63 ± 0.20 and 7.32 ± 0.11 and a temperature range of 27.3 ± 0. 76 and 29.9 ± 0.41 degrees celsius. (au)