On-site treatment of contaminated soils and wastes from transportation maintenance activities using oxidative processes

The treatment of contaminated timbers and soils was investigated by using catalyzed hydrogen peroxide, a procedure based on Fenton's reagent [hydrogen peroxide and iron(II)]. The process produces hydroxyl radicals, which oxidize nearly all organic contaminants. Wood posts contaminated with pentachlorophenol (PCP) and creosote were treated by the peroxide process, resulting in 84% degradation of the PCP and 74% degradation of the creosote with 6% hydrogen peroxide and 56 mg of Fe per L. The estimated cost was $18/kg of wood. A natural soil contaminated with 1000 mg of diesel fuel per kg was treated with a matrix of five hydrogen peroxide concentrations (1000, 5000, 10,000, 50,000, and 100,000 mg/L) and four slurry volumes (5, 10, 20, and 30 times the field capacity of the soil). The most efficient treatment was found with 1000 mg of hydrogen peroxide per L at a volume of 30 times the soil field capacity, with an estimated hydrogen peroxide cost of $15/909 kg (1 U.S. ton) of soil. Catalyzed hydrogen peroxide soil remediation may be implemented through a number of process configurations, including in situ and ex situ applications. The methodology also meets the primary policy goals of state and federal regulatory agencies, in that the waste components can be mineralized to carbon dioxide and water, which are nontoxic end products.