e aim of this work is to present an integrated process for the remediation of soils contaminated with o,o-dimethyl o-(pnitrophenyl)phosphorothioate, known as methyl parathion (MP), by surfactant-enhanced soil washing and treatment of the produced wastewaters in an aerobic-submerged bio lter. Soils containing approximately 0.4 and 13 mg/kg of MP were washed using anionic, nonionic, zwitterionic, and natural surfactants. Between 63 and 98% of the initial concentrations of MP were removed. Wastewater produced from soil washing with the addition of a natural biosurfactant, locust bean gum [0.01% (w/w)], was used for the experiments in an aerobic-submerged bio lter in which MP concentration decreased from an initial value of 0.78 mg/L up to a value of 0.05 mg/L in 6 days, indicating the feasibility of the treatment proposed.