Application Of Biodiesel To Remediate Crude Oil Polluted Gravel Beach In Laborotary Simulation Test

Biodiesel is easy to be biodegraded, and it is a good solvent that can increase the dispersion and solubility of crude oil. It’s of great significance to study the application of biodiesel in oil-polluted gravel beach. In this paper, the feasibility of using biodiesel to promote the release of crude oil from polluted gravel through simulation experiment was studied first, and the effects of biodiesel with different quantity, adding method and time on different kinds of crude oil were discussed. Secondly, the joint bioremediation of biodiesel and nutrient on oil-polluted gravel beach was studied, and the effect of N, P ratio and different coastal environment factors on bioremediation were discussed. Finally, the toxicity effect of biodiesel to the crude oil polluted water was explored. The results are as follows.Biodiesel have a obvious effect in promoting the release of oil from polluted gravel; The release quantity of crude oil increased with the amount of biodiesel When biodiesel additive amount reaches a certain value, the promoting function of the release could not increase significantly. When the rate of crude oil and biodiesel was2:1, the release rate was74.6%. When the rate was4:3, the release rate was84.5%.The addition of biodiesel in more than one time is better than one-off dosing on account of their promotion effect. The removal efficiency of adding biodiesel in three times was about24.6%higher than one-off dosing in the release of crude oil after the9days experiment.The longer the crude oil weathering, the weaker effect of biodiesel on promoting the oil release. When the crude oil was treated directly without weathering, the removal efficiency can reach as much as64.6%. As to the light oil and heavy oil, biodiesel can promote light crude oil release faster than heavy oil.Appling biodiesel and adding N,P nutrition both can promote the biodegradation of crude oil, improve the quantity and activity of microorganisms in the seawater. When the ratio of N and P was6:1or8:1, the degradation rate of crude oil released to seawater was84.1%or80.8%.When the ratio of N and P was4:1or10:1, the degradation rate was only54.3%or69.4%. This suggest that6:1and8:1are better ratios for the bioremediation relatively.The more dissolved oxygen in seawater, the faster crude oil was degraded, and the higher quantity and activity of microorganisms were. Under this experiment condition, the dissolved oxygen content in the seawater of4.6mg/L can be enough to meet the needs of the bioremediation; Where the seawater exchange frequently, it’s release rate and bioremediation effects of crude oil is better and more conductive to bioremediation in the oil-polluted gravel beach.The more crude oil the seawater content of, the stronger toxicity. So the bioremediation of crude oil can reduce the toxicity of oil pollution environmental; In this experiment, four kinds of biodiesel were used in the ratio of2:1,1:1and1:2to crude oil. But it had little impact to the toxicity of seawater with crude oil. So the application of biodiesel in the crude oil polluted gravel beach is feasible.