Current World Environment

In this study, Polycyclic Aromatic hydrocarbons (PAHs) contaminated soil were collected from Ray Petrochemical industry and treated by Solidification/Stabilization (S/S) which is an effective technique for reducing the leachability of contaminants in soils. Since organic compounds interfere with cement hydration process, S/S technology will have difficulties while trying to immobilize organic contaminants. The treatment process was conducted using Portland Cement (PC) as the main binder and Microsilica (MS) as an additive to improve the effect of PC in immobilization of organic contaminants. Specimens were divided in two groups with constant cement percentage of 25% and 35%. Each group were again divided to three subgroups with 0%, 4% and 8% of MS. The efficiency of using MS in leaching behaviour of S/S samples was assessed by toxicity characteristic leaching procedure (TCLP). Lowest leach percentage of 14.66% for total PAHs in the paste contained 25% of cement and 8% of MS were obtained. The results indicated that the presence of MS in cement pastes had positive effect on reduction in concentration of contaminant in leachate.