Deep purification of industrial waste salt containing organic pollutants by a dry method with Non-thermal plasma

The deep removal of organic impurities is one of the key factors limiting the reuse of regenerated industrial waste salt. In this study, a dry process based on dielectric barrier discharge (DBD) plasma has been developed for the deep removal of organic impurities of waste salt in solid state, which has the most important advantage of avoiding the generation and the subsequent treatment of high salinity wastewater. The purification effects of DBD plasma on ciprofloxacin (CIP) contained simulated waste salt and actual industrial waste salt were revealed. The removal of organic impurities is influenced by the discharge parameters, carrier gas characteristics (including gas species, flow rate, relative humidity) and waste salt characteristics (including particle size, water content, organic pollutant content). At the optimal treatment conditions, the residual CIP content can be reduced to 12.1 mg/kg and a 76.6% removal of TOC can be obtained. The maximum finial energy yield and energy yield at 50% conversion are 0.73 g/(kW.h) and 1.33 g/(kW.h), respectively. The degradation mechanism of CIP was proposed basing on the degradation intermediates. The experimental results indicate that DBD plasma can be used for the solid refining of organic pollutant contained industrial waste salt. This dry method presents obvious better performance than traditional solution methods, which can effectively promote the regeneration and reuse of industrial waste salt.