Bioturbation enhances the removal of petroleum hydrocarbons in sediments by bacteria

Abstract

A labortatory experiment was designed to study the removal of total petroleum hydrocarbons (TPH) by bacteria-bioturbation in the sediments. TPH were detected on 0, 5, 10, 14, 17, 20, 24 d in different phases and the removal rate in different layers of TPH in sediments was measured. The results showed that there were three results about the fate of TPH in the sediments: transfering to seawater by bioturbation; accumulating in the worms by feeding and degrading by bacteria. The removal rate of TPH in joint repairing group (JRG) was obviously higher than other three groups and reached to 86.01%, 83.58% and 75.56% in upper, middle and lower layers, respectively. The concentration of TPH increased 2.9264 mg/L in seawater and 12.7514 mg/kg in worms, imply that feeding by worms is an effective way to remove TPH in the sediments. The result of orthogonal experiment in the laboratory demonstrated that the best conditions to remove TPH by bacteria-bioturbation is: A. density of worms, 200 ind/m2; B.volume of bacterial fluid vaccination, 25 mL; C. salinity of seawater, 23; D. pH of seawater, 8.5; E. cultivation time, 12 d.