Material flow analysis and heavy hydrocarbon removal in a full-scale biopile and soil washing plant in northern Italy

This study aimed to assess the mass fluxes and removal efficiencies of heavy hydrocarbons in a full-scale plant located in northern Italy. This plant receives and treats contaminated soil, soils and rocks from construction and demolition activities, incineration slags and street cleaning residues. The plant has three sections, consisting of bioremediation using biopile, a soil washing stage and a stabilization/solidification unit, which can perform independently or together with the others. The material flow analysis showed how the crisis in the construction industry changed the final destination of waste after the treatment: as the market demand for coarse material decreased, waste was sent directly to landfills for inert waste, instead of being recovered. Hydrocarbon mass fluxes showed that a considerable amount of pollutants was removed. In the period 2009–2014, the removal efficiencies of the bioremediation, the soil washing section and the entire plant were respectively 73%, 58% and 62%. The percentages of removal attained at the facility in study were sufficient to ensure the possibility of recovering the waste or disposing of it in different landfill categories, according to the national regulations.