Hydrocarbon Removal From Sediment By Synergistic Effects Of Worms And Microorganisms

Marine sediment oil pollution,mainly caused by diesel leak,is a common problem in the world,which can be repaired by biological methods.Using diesel as a pollution source,sediment samples collected in the intertidal zone of the Gaoshan Mountains were poisoned.Separate and joint experiments on microorganisms and worms were conducted to explore the effect of removing petroleum hydrocarbons in the sediments,and then the whereabouts of TPH were tracked.Based on the joint experiments,an orthogonal experiment was designed to optimize the TPH removal effect of the worm-microorganism synergy.The main conclusions based on the experiments are as follows:(1)The growth curve and petroleum hydrocarbon degradation rate of four strains of existing bacteria were compared and the results showed that the all the growth curves of them conformed to the "S" type growth,but the activity of CH5 was stronger.In addition after 21 days of petroleum hydrocarbon degradation experiments,CH5 had the highest TPH removal rate of 8.364%,CHI removal rate of 6.405%and CH4 removal rate of 6.669%.However,the removal rate of CH3 was lower than that of the control group,which showed that the degradation effect of CH3 on TPH was poor,and CH5 was the microorganism that met the experimental conditions.(2)The petroleum hydrocarbon removal rates of the upper,middle and lower sediments caused by the biological disturbance of the worms were 31.48%,30.77%and 11.07%,respectively.The amount of TPH released into the water due to biological disturbance was about 4.22 mg/L,and the amount of TPH accumulated to the worms due to feeding was about 22.766 mg/kg.In addition,GC-MS was used to determine the diesel components before and after the experiment.It was found that the main component of the diesel used in this paper is linear alkanes,accounting for about 71%of all components.The type of petroleum hydrocarbons removed by bioturbation is also mainly linear alkanes.The carbon contents distribution were C9-C31,and the removal rate ranges from 40%to 95%,which indicated that the bioturbation has a good effect on the removal of linear alkanes.(3)There were some kinds of results in the worm-microorganism collaborative experiment.In the presence of only microorganisms,the removal rates of TPH in the upper,middle and lower sediment layers were 2.55%,4.40%and 7.27%,respectively.In the presence of only worms,the removal rates were 4.63%?1.23%and 2.05%.Under the conditions of coexistence of worms and microorganisms,the removal rates were 8.63%,9.06%and 8.03%,respectively.In the two experimental groups in which worms existed,the TPH accumulated in the worms were 12.47 mg/kg and 12.75 mg/kg,which were basically the same.The amount of TPH eventually transferred from the sediments to the water in each experimental group was lower than that in the control group.Therefore,the removal of TPH in the sediments mainly depends on the degradation of microorganisms and the feeding effect of the worms.The variance analysis in the orthogonal experiment of worm-microorganism cooperative remediation indicated that the main factors affecting the experimental results were the density of worms and the salinity of seawater.