Remediation of Petroleum Contaminated Tidal Flat Sediments by Co-bioremediation System

The remediation effects of oil-degrading bacteria, Nereis succinea and Suaeda heteroptera, on oil-contaminated sediments were studied by laboratory pot experiments under simulated conditions of intertidal zone. Three concentrations of oil-contaminated sediments (I: 500 mg/Kg, II: 1500 mg/Kg, III: 3000 mg/kg) and four bioremediation treatment groups (bacteria group, bacteria-N. succinea group, bacteria-S. heteroptera group, bacteria-N. succinea-S. heteroptera group) were set up, and the oil removal efficiency was measured after 15, 30, 45, 60, and 70 days of the experiment, respectively. The results showed that the percent removals of total petroleum content, linear hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) of each sediment under all bioremediation treatments were significantly higher than those of the control groups (P < .05). The bacteria - N. succinea - S. heteroptera synergistic model performed best, after 70 days of remediation tests, the percent removals of total petroleum content reached 51.9%, 47.8%, and 40.6% under I, II, and III oil concentration conditions, respectively, indicating the biological disturbance caused by N. succinea and the rhizosphere effect of S. heteroptera can effectively promote the oil removal of the bioremediation system. In addition, the oil degradation speed in each bioremediation combination showed an increasing trend in the began month, peaked during 15-30 d period, and then decreased obviously at 30-70 d in all bioremediation treatments. We also found that the synergistic bioremediation models promoted the removal of petroleum linear hydrocarbons and PAHs, and the percent removals of linear hydrocarbons were negatively related to their carbon chain length, and the removal rates of PAHs decreased significantly as the number of benzene rings increases. The above results demonstrated the feasibility of co-bioremediation technology in the remediation of petroleum contaminated tidal flat sediments.