CONTAMINATED SOIL BIOREMEDIATION PLANT

The designed plant provides for the off-site biological treatment (biopile) of hydrocarbons contaminated soil; the purpose is to lead the concentration of contaminants back to the limit of the environmental law for the recovery of the soil in the original or different sites. The incoming trucks discharge waste into a feeding hopper with a grid to separate finest soil from coarse materials; then soil are put into the mixing system where nutrients (N and/or P), water (recirculated) and bulking materials (when needed) are added according to the starting chemical composition. Therefore, a conveyor carries the mixed soil to the storage area waiting for the biopiles arrangement. The storage area can receive up to 1,500 m³ of soil. Each biopile has a volume of about 450 m³, with maximum 2.5 m height and it is equipped with air insufflation system, probes for monitoring the Total Petroleum Hydrocarbons, CO₂ and O₂ amounts and an adequate irrigation system for the humidifying. A 1.5 mm thick polyethylene coverage are put over each biopile, so all treatment conditions can be uniform and kept under control. Therefore the biological treatment can start. During the process, which is about three months long, major parameters (TPK, CO₂ and O₂) are controlled with the possibility of water injection through the irrigation system, monitoring the mass balance (water decreases due to the evaporation caused by forced air insufflation but it increases due to the biological reactions). When the process is complete, the biopile is removed and remediated soil is put into the storage lanes waiting for the final recovery.