BIOTREATABILITY OF PETROLEUM REFINERY SLUDGE USING LAND - FARMING AND ANAEROBIC DEGRADATION TECHNIQUES

Abstract

One of the major problems faced by oil industries and the environment, is the safe disposal of oily sludge generated during the processing of crude oil. Biotreatability of petroleum refinery sludge using bioremediation and anaerobic degradation techniques was studied. Analysis of the Nigerian Petroleum Refinery sludge used for this research indicated that the sludge is slightly acid with high total petroleum hydrocarbon (TPH) content of 340,000mg/kg and polyaromatic hydrocarbon (PAH) content of 0.075mg/kg. The heterotrophic bacterial and fungal counts were 5.86 x 105 and 4.72 x 105cfu/g respectively while the hydrocarbon degrading bacterial and fungal count were 2.85 x 102 and 2.75 x 102 cfu/g respectively. Results from biotreatability studies revealed that the sludge contamination at lower concentration 10,000 (1%) mg/kg, recorded high percentage degradation than the treatment with higher sludge concentration, 50,000 (5%) mg/kg. Biostimulation treatments enhanced the sludge degradation better than the natural attenuated treatment. Volume of biogas produced in the anaerobic microcosm was highest in the treatment with compost in both 1% (10.73 l/kg) and 5% (9.27 l/kg) sludge treatments. Though the NPK treated soil enhanced the biodegradation of sludge most, degradation started declining by the 9th week while that of compost continued to rise steadily till the 12th week. Anaerobic process was quite slow and did not degrade the sludge as much as the aerobic land – farming method.