Bioremediation of oil from polluted wastewater using sand biofilm system

Eight bacteria were isolated from grease-oily industrial wastewater, only 4 bacterial isolates found to have the ability to degrade oil and grease in contaminating wastewater. These isolates were identified according to morphological and biochemical tests as, Pseudomonas sp. (L I), P. diminuta (L2), P. pseudoalcaligenes (L3), and Escherichia sp. (L5). Bacterial isolates were tested individually or in combination using synthetic aqueous medium supplemented with 1% palm oil, incubated at 30degreesC, and agitated at 150 rpm for 13 days. The combination M1 (Pseudomonas sp. and P. diminuta) produced the highest degradative activity, followed by M3 (Pseudomonas sp., P. diminuta and P. pseudoalcaligenes). Therefore, M1 combination was used in a biofilm sand filter system (one unit or 2 units in sequence), where different flow rates (30, 50, and 100 mL/h) were tested. Results showed that both biofilm system reduced oily wastewater even in case of high degree of pollution (FOG, 7535 ppm; BOD, 525 ppm; COD, 1660 ppm). Results also showed a removal of FOG with efficiency at 100%; BOD at 95.9%; and COD at 96%, at 50 mL/h flow rate using one unit of biofilm system. On using two units in sequence, a complete removal of FOG, BOD, and COD with efficiency 100%, at flow rate 100 mL/h was achieved. On conclusion, the previous biofilm results indicated the efficiency of such system in treating oily-polluted wastewater on basis of bacterial isolates being used, the optimum flow rate, and the number of biofilm units used in sequence to obtain the highest removal capacity of such system.