Study And Application Of Petroleum-contaminated Soil By Ex-situ Washing Remediation Technology

Petroleum pollutant is a kind of series persistent organic pollutant. It has great concerned, since petroleum ingredient has toxicity and physical function of damaging biological normal living environment or leading biological functional barrier.Technology of Petroleum-contaminated soil by Ex-situ Washing Remediation is a rising and economic-efficiency technology in international environmental science and engineering. Its principle is that using washing liquid washes the petroleum-contaminated pollutant which stays in pore of media. The liquid with pollutants are extracted from soil layer and separated and processed. This process is aimed to remediate petroleum-contaminated soil. Hence, choosing of high cost-efficiency washing liquid is the key on effect of ex-situ chemical washing remediation.This paper has done the research about Petroleum-contaminated soil by Ex-situ Washing Remediation. Investigation of negatively charged cationic surfactant and helper-agent to petroleum-contaminated soil remediation is below:(1) The best washing formula is 5 (Triton-X100):10 (Sodium lignosulfonat):42 (Sodium silicate):43 (Sodium carbonate) which removal oil rate is highest, account for 50%, through washing rate based on optimization of combination.2. Washing waste water process is using flocculating agent-hyperfiltration membrane technology. Oil concentration is less than 0.14mg/L, SS is less than 1 mg/L and CODCr is less than 41mg/L after process. These indexes meet water release and reinjected water standard. This process has implemented water resources recycle.3. Outdoor remediation engineering experiment shows that remediation of high level of petroleum-contaminated soil was 105.6 cubic meter within 6 months ex-situ remediation. Average removal rate of total petroleum in contaminated soil is 97.5%. The concentration of total petroleum hydrocarbon basically meets planting soil requirements after processed.4. Toxicity of soil decreases after washing remediation. Lighten rate of QingHai Lake luminescent bacteria shoot up remarkably from 43.2 to relative lighten value 97.7 that is approaching clean soil requirements. The basic physicochemical properties of soil have changed significantly after leaching. Soil fertility decreases and nutrition status is not good.5. Discussion of petroleum group ingredients in soil changes during washing remediation petroleum-contaminated soil shows that concentration of petroleum decreases, which saturated hydrocarbon has fastest decreasing speed, with more frequently washing.The content of oil group components reduced by washing might be releated to the polarity of the component.As above mentioned, petroleum-contaminated soil ex-situ washing remediation shows that complex washing solution can remove petroleum contaminations fast and efficiently. Leaching waste water would be recycled in cost-effectiveness. Although physicochemical properties of soil has changed greatly after washing, toxicity of soil declines significantly and there is a low effect on health situation of soil. Thus, petroleum-contaminated soil ex-situ washing remediation technology is feasibility remediation method.