原位还原稳定化—高压旋喷注射技术修复铬污染场地中试研究

Remediation of Chromic-contaminated Site by in Situ Reduction and Stabilization-high Pressure Jet Injection Technology at Pilot-scale Studies

根据场地土壤条件(如pH、渗透性、地下水位等)、污染程度和前期小试效果,选用高压旋喷注射技术,将硫化物和矿物质组成的还原型药剂注入污染土壤中,还原Cr^(6+)为Cr^(3+),从而降低土壤中Cr^(6+)含量和毒性。中试结果表明,在注射压力为10 MPa,影响半径为0.5 m,提升速率为10 cm/min,药剂投加比为3%时,修复后的土壤Cr^(6+)含量<0.5 mg/kg,低于修复目标值0.75 mg/kg,达标率为100%。另外,六价铬和总铬的浸出毒性均低于《GB8978-1996污水综合排放标准》中的第一类污染物最高允许排放浓度,达到了预期的修复目标值,且药剂的加入不会对土壤pH造成较大影响。原位还原稳定化—高压旋喷注射修复技术成功应用于某铬盐厂中试,修复效果明显,适应于类似污染场地的浅层土壤修复。

According to the soil conditions（ such as p H,permeability,groundwater level,etc.）,and the degree of pollution and the experimental results in laboratory,high pressure jet injection technology was selected to inject the remediation agent consisting of sulphides and minerals into contaminated soil to reduce hexavalent chromium to trivalent chromium. The content and toxicity of hexavalent chromium in soil were decreased. The results of the pilot test showed that when the injection pressure was 10 MPa,the radius of influence was 0. 5 m,the lifting rate was10 cm/min and the remediation agent addition was 3%,the content of hexavalent chromium in the soil was reduced to less than 0. 5 mg/kg,which was lower than the remediation goal value of 0. 75 mg/kg. The rate of reaching the standard was 100%. In addition,the leaching toxicity of hexavalent chromium and total chromium was lower than the upper limit for emission concentration of the first type of pollutants in the integrated sewage discharge standard（ GB8978-1996）. It has achieved the expected value of the remediation goal. And the addition of the remediation agent didn＇ t have a great influence on the soil p H value. In situ reduction and stabilization-high pressure jet injection technology was successfully applied in a chromate plant and the effect of remediation was obvious. This technology is adapted to remediate the shallow soil of similar contaminated sites.