(564b) Biodegradation of Refinery Wastewater by Free and Immobilized Bacillus Cereus

Refinery wastewater samples from two different sites (Indian Oil Corporation Limited (IOCL) and Oil India Limited (OIL)) were treated by the isolated strains Bacillus cereus AKG1 MTCC9817 and AKG2 MTCC9818. The effects of various operating parameters on the removal efficiency of pollutants in terms of biological oxygen demand (BOD), chemical oxygen demand (COD), and ammonium-nitrogen (NH4+- N) are studied. In the short period of time (20 days), co-culture free cells of the isolated strains have been able to remove higher COD (83.78% for IOCL sample and 70% for OIL sample) than the immobilized cells (24.32% for IOCL sample by Bacillus cereus AKG1 MTCC9817; 10.81% for IOCL sample by Bacillus cereus AKG2 MTCC9818 and about 10.25% for OIL sample by both the above strains). Similarly, higher NH4+- N removal was observed by co-culture (68.12% for IOCL sample and 69.45% for OIL sample) than immobilized system (31.5-42.46% for various combinations). The experimental results, thus, indicated that the free cells are more active than the immobilized ones and the co-cultured free cells is the best option for treatment of phenol containing refinery wastewater.