Degradation of DDTs in thermal desorption off-gas by pulsed corona discharge plasma.

Thermal desorption has been widely employed to treat soils contaminated with chlorinated organics. The off-gas of thermal desorption must be treated to avoid secondary pollution. In this study, the treatment of DDTs in thermal desorption off-gas by pulsed corona discharge plasma was investigated. The effects of important operation parameters, including energy density, gas temperature, humidity, and O2 content, on DDTs degradation were investigated. The main degradation products were also studied. The DDTs degradation efficiency increased with the increase in energy density, gas temperature, and O2 content. The degradation efficiency of DDTs was achieved to 84.6% when the initial concentration, energy density, and gas flow rate were 2.0 mg/m3, 17.8 J/L, and 3.0 L/min, respectively. Maximum DDTs degradation efficiency was observed when the gas was at 5% relative humidity. The main degradation products identified were DM, phenol, benzene, acetic acid, and formic acid. It was calculated that 87% of chlorine in the degraded DDTs was converted into chloride ion.