Abstract:
The main objective of this study aims to isolate bacterial consortium capable of degrading lubricant oil in gas station wastewater. Consortium SL was isolated from Suan Lumpini gas stations wastewater comprised of four bacteria SLY, SL15, SL17 and SL27. Base on their 16S rDNA sequences along with morphological and biochemical characteristics these strains were identified as members belongs to the genus of Sphingobium sp. Acinetobacter sp. Ochrobactrum sp. and Alcaligenes sp., respectively. As for their abilities the biodegradation of oil, when such consortium was incubated in synthetic oil/water emulsion at initial oil concentration of 100 mg/L for 7 days at room temperature, the oil level was reduced down to 34% while 35 and 32% were also observed in case of saturate and aromatic fractions. It was also found that strain SLY individually can also degraded lubricant oil as well as the other two fractions. The optimal condition for biodegradation were initial oil concentration of 50 mg/L, nitrogen content of 10 mg/L and phosphorus content of 1 mg/L at pH 7.5 and 35 °C. The consortium SL reduced lubricant oil at the optimal condition to 31% whereas strain SLY failed to enhance the effect. Microcosms experiment was carried out to study its degrading ability in gas station wastewater by adjusting initial oil concentration to 50 mg/L. After 7 days, the system supplemented with consortium SL showed higher degradation than natural attenuation. Result from DGGE revealed dynamic of bacterial population in this consortium and confirmed the present of consortium SL with more dominance than indigenous microorganisms throughout the entire period of study.