Surfactant-enhanced bioremediation of DDTs and PAHs in contaminated farmland soil

Field-scale bioremediation of dichlorodiphenyl trichloroethanes (DDTs) and polycyclic aromatic hydrocarbons (PAHs) contaminated farmland soil from the Shenyang North New Area of China was studied using the bacteria Arthrobacter globiformis. The additive effects of different concentrations of biosurfactant rhamnolipids (RLs) and anionic-nonionic mixed surfactant (SDBS-Tween 80) were evaluated. DDT and PAH removal rates by A. globiformis after 150days of remediation were 52.1% and 21.9%, respectively. At the optimum RL concentration of 5mgkg(-1), DDTs and PAHs had removal rates of 64.3% and 35.6%, respectively, at 150days. This was 60.7% and 29.3% higher than the control; 36.9% and 19.8% higher than soil with RL-5 alone; and 12.2% and 13.8% higher than the A. globiformis treatment alone. RL-5 can enhance soil enzyme activity and A. globiformis reproduction during the DDT and PAH biodegradation processes. This study illustrates a highly efficient, low-cost in situ soil bioremediation technology that could have practical utility.