Preliminary Study On Remediation Technology Of Petroleum Contaminated Soil

As one of the raw materials of industry and energy,petroleum has brought serious environmental problems while it promotes the development of human society.Due to the poor solubility of petroleum,it is easy to adsorbe to the soil particles,and with the extension of time,it is mainly bound to residues in the soil.The petroleum in the soil can accumulate in the plants,and inhibit the growth of plants.Humans can absorbe pollutants by food chain,petroleum pollutants can be absorbed by humans through the food chain,and ultimately endanger human health.Therefore,it is very important to carry out the remediation of petroleum contaminated soil.However,so far,there is no fast,efficient and safe method for petroleum contaminated soil remediation.This article taked petroleum as the target pollutant,carried out the research of activation of sodium persulfate remediating petroleum contaminated soil,and developed an environment-friendly and highly efficient remediation technology.This article mainly included the following aspects:(1)Screening of green remediation agent for diesel contaminated soil;(2)To optimize the parameters including of water-soil ratio,temperature,initial concentration of petroleum contaminants and pH,which affect the removal efficiency of disel oil in the soil;(3)Study on the practical application of sodium persulfate which was activated by zero valent iron and calcium peroxide.The results of the screening of green remediation agent for diesel contaminated soil showed that comparing with hydrogen peroxide and ferrous ion,calcium peroxide and zero valent iron could better activate sodium persulfate and could effectively romove the disel from the soil.When the dosage of sodium persulfate was 2 mmol/g and Na2S2O8/CaO2/Fe0(molar ratio)was 5/2/2,the removal rate of disel oil was higher than 82.33%.In addition,the removal rate of disel oil was increased by 26.01%compared to the control.The results of the effect of outer factors on the disel oil removal showed that with the increase of water-soil ratio,the removal rate of disel oil was gradually increased and then stabilized,and 2.5/1 was the optimal water-soil ratio.The effect of temperature on the removal rate of disel oil was mainly reflected in the removal rate,which had little effect on the final removal rate.From a practical point of view,25℃ was chosen as the suitable temperature.With the increase of initial concentration of disel oil,the removal rate of disel oil increased gradually,which indicated that the oxidation reagents had better performance so that they could be used to remediate high concentration petroleum contaminated soil.The initial pH had no significant effect on the removal of diesel oil,and it is not necessary to consider the effect of pH when the system is used in engineering.The results of the study about the practical application of sodium persulfate activated by zero valent iron and calcium peroxide suggested that the removal rate in high concentration petroleum contaminated soil was markedly lower than in disel oil contaminated soil.In order to solve this problem,the experiment adopted the methods of prolonging the reaction time,increasing the dosage of reagents and secondary treatment to improve the removal rate of disel oil.The results showed that there was no significant effect on the removal rate of petroleum in soil by prolonging the reaction time;increasing the dosage of oxidant and activator could elevate the rremoval rate of petroleum,but the residues of petroleum in the soil was high;when the petroleum contaminated soil was treated for two times,the removal rate of petroleum was increased significantly which was high as 92.47%and 93.94%.The system could reduce the concent of soil organic matter,total nitrogen,total phosphorus,total potassium,but it could enhance seed germination rate.In summary,the system of sodium persulfate activated by zero valent iron and calcium peroxide can be used to remediate high concentration and refractory of petroleum contaminated soil.The optimum technique parameters were:2.5/1 of water-soil ratio,25℃,and 4 h of treatment.