Remediation of organochlorine pesticides contaminated soil using thermal plasma

Abstract

Organochlorine pesticides have been used widely in agriculture for effective pest control. However, organochlorine pesticides such as dichloro-diphenyl-trichloroethane (DDT) contaminate soil, groundwater and cause carcinogenic effects, reproductive disorders for birds, humans and other mammals. Consequently, the use of DDT in agriculture has been gradually forbidden since 1972. Nevertheless, due to the long halflife of DDT (~36 years), its residues are still present in the soil. Therefore, there is a need to find a method for the treatment of this dangerous contaminant in the soil. This experimental research is aimed to analyse thermal air and water vapour plasmas eligibility to remediate soil contaminated by organochlorine pesticides (mainly DDT). Hence, parameters of the polluted soil were investigated before and after the treatment with thermal plasma using scanning electron microscopy (SEM), an optical microscope, a photo camera, energy dispersive X-ray spectroscopy (EDX) and gas chromatography-mass spectrometry (GC-MS). SEM analysis revealed that interaction of polluted soil with thermal air plasma or water vapour plasma caused structural changes of the soil. EDX data demonstrated complete removal of chlorine after the soil cleaning with plasmas. Moreover, the measurements performed with GCMS confirmed that organochlorine pesticides concentrations in the soil were reduced noticeably after the soil cleaning with thermal plasmas. Thus, experimental results indicate that contaminated soil treatment using thermal air or water vapour plasma has satisfactory pesticides degradation capacity.