Removal of petroleum hy drocarbon from water by using isolated bacteria from diesel contaminated soils

Removal of low concentrations of petroleum hydrocarbons from water by physico-chemical methods encounters many limitations. The aim of this study was thus isolation and identification of bacteria from soils contaminated with total petroleum hydrocarbons (TPH). Removal efficiency of low concentrations of hydrocarbons from water using isolated bacteria was also determined.

TPH concentrations of 100, 500 and 1000 ppm in water were examined. Bacteria were identified and isolated from diesel-contaminated soil. Isolated bacteria were cultured separately in medium containing water with certain concentrations of TPH. At predetermined contact times (2, 5, 7 and 14 days), the total amount of TPH remained in the water was measured using standard methods.

At 100 ppm TPH in water and within 48 hours, the highest removal efficiency of TPH about 65% was obtained by Alkaligenes faecalis. Likewise, the lowest removal performance of TPH, approximately 20%, was obtained by Pseudomonas aeruginosa at this concentration. The highest and lowest removal efficiency of TPH from water at 500 ppm by was achieved by Enterobacter (40%) and Alkaligenes (20%) following 48 h, respectively. At the highest concentration of TPH in water (1000 ppm) and after 48 h, the highest removal rate about 30% was obtained by Enterobacter. for the removal efficiency appeared to increase with the increase of contact time, in which the maximum removal efficiency was about 90% (at 100 and 500 ppm concentrations) and about 50% (at 1000 ppm concentrations) after 14 days.

Bacteria isolated from contaminated soil can be used to remove low concentrations of petroleum compounds from water.