Remediation Of Petroleum Contaminated Soil By Plant-Microbicl Method

Petroleum is an important part of the world's energy.With the increasing demand for petroleum,the petroleum industry has developed rapidly.However,spills and leaks during the extraction,storage,transportation,processing and use of petroleum have caused large areas of soil pollution.Repairing petroleum-contaminated soil has been a hot spot and difficulty in ecological and environmental protection work at home and abroad.Phytoremediation and microbial remediation have attracted much attention in the field of soil remediation due to their low cost and environmental friendliness.Relevant research results showed that the combination of phytoremediation and microbial remediation can make up effectively for the shortcomings of a single remediation method and strengthen the remediation effect.Ryegrass,alfalfa and festuca arundinacea were selected as experimental plants,and pseudomonas aeruginosa was used as the test agent to explore the effect of plant-microbe remediation of oil contaminated soil.Firstly,the remediation effects of three bioremediation methods,phytoremediation,microbial remediation and plant-microbe remediation,on petroleum contaminated soil were compared.The results showed that plant-microbe remediation's effect was significantly better than the single remediation method,after 56 days of treatment,62.6%-71.9%of the petroleum in the soil could be removed.The alfalfa-microbe remediation's degradation rate of petroleum was 24.9%higher than the single alfalfa remediation group and 48.3%higher than the microbial remediation group.The removal rate was also significantly faster than the single repair method,and the rate constant was 0.0091 d^-1?0.0015 d^-1.The ryegrass-microbe remediation'removal rate was as 1.6 times as the single ryegrass remediation group and 2.7 times as the microbial remediation.The comprehensive effect mechanism was inferred that the symbiosis of high efficient petroleum degrading bacteria and plants promoted the growth and development of plants in the plant-microbe remediation system.Compared with the single phytoremediation method,the plant height and leaf width increased,and the root system was more developed.The degradation of organic matter by plants and root exudates also made the growth and reproduction of high efficient petroleum degrading bacteria faster.Therefore,the remediation effect of petroleum contaminated soil was better.Secondly,the effects of initial oil content in soil,plant density,amount of bacteria and site conditions on the combined plant-microbe remediation were investigated.The results showed that when the content of petroleum hydrocarbon in soil was 0.6%,the plant density was 2 plants/10 cm²,and the amount of bacteria added was 20 g/kg soil,not only good remediation effect could be achieved,but the remediation system could be fully utilized.The best site conditions for plant-microbe remediation were p H 7?8,treatment temperature25?,soil moisture content 50%,N/P ratio:10:1,and regular tillage.Under these conditions,the degradation rate of petroleum in soil was the highest with 85.5%.Finally,the preliminary practice of plant-microbe remediation of oil contaminated soil was carried out.The results showed that after the expansion of the scale of remediation,the restoration effect of the the combined plant-microbe remediation system did not change significantly,and the remediation did not have a significant impact on the physical and chemical properties of soil.The petroleum content,COD,TN,ammonia nitrogen and TP in the soil leachate were low,and the p H was neutral.Compared with the tap water irrigation mode,the sewage tail water irrigation mode has better restoration effect,and could save water resources and reduce treatment cost.In conclusion,the method of the combined plant-microbe remediation can remove petroleum in soil more efficiently,which has a good application prospect in the remediation of oil contaminated soil.