The treatment and disposal of petroleum oily sludges represent major challenges for petroleum industries. The oily sludges consume a high portion of a refiner's budget and pose a serious threat to the environment. Montreal and Kyoto protocols introduced significant restrictions on the disposal of petroleum wastes and reduced the options available for treating this type of hazardous wastes. This research considered the application of bioremediation principles to petroleum oily sludge using a new testing technique. Approximately, 35% of the total petroleum hydrocarbons, and 81% of the aliphatic hydrocarbons in the sludge were degraded using a fungal-bacterial co-culture. To my knowledge, this was the first time fungal-bacterial co-cultures have been used in the treatment of petroleum oily sludge. Prior to treatment with the co-cultures, the sludge was subjected to a special electrokinetic separation technology that reduced its oil and water contents. The cultures were isolated from petroleum oily sludge taken from the bottom of crude oil storage tanks. The fungal and bacterial strains, used in the co-culture, were identified as Paecilomyces variotii and Bacillus cereus, respectively. The cultures were inoculated on 0.22 mum filters laid over the sludge. Reduction in aliphatic hydrocarbons was estimated using Fourier transform infrared spectrometry (FTIR). Total Petroleum Hydrocarbons (TPH) were estimated using solvent extraction. An amphoteric surfactant was used in the studies but it did not improve biodegradation rates. The testing technique gave a comprehensive indication of the efficiency of the process and the toxicity of the sludge for defined cultures of the microorganisms.
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