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

Abstract

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 hydro-carbon-degrading microbes used for the study were isolated from oil-contaminated soil and fur-ther 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, tempera-ture, 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 mini-mum 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 °C.