Phytoremediation of Oilfield Sludge After Prepared Bed Bioremediation Treatment.

A field-scale experiment was carried out to compare the effectiveness of five plant species in the remediation of oily sludge. Alfalfa, tall fescue, and soybean substantially increased the removal rate of oil and grease (O&G) after 120 days of remediation. Of these, soybean treatment showed the highest removal rate of 34.2% compared with only 13.7% in the unplanted control plot. In addition to assisting with phytoremediation, soybean can also be used for energy production, for example in the production of biodiesel. Furthermore, microbial counts and community level physiological profiling using Biolog sole carbon source utilization tests were used to investigate the effect of plants on the microbial community of oily sludge. Plants selectively increased microbial counts in the rhizosphere and O&G concentrations of the sludge were negatively correlated with counts of TPH (total petroleum hydrocarbon) degraders. The acute biotoxicity of the sludge was also tested by the bacterial luminescence method and alfalfa treatments decreased the biological toxicity of the sludge compared with the unplanted control. [ABSTRACT FROM AUTHOR]