ABSTRACT
Caprolactam (CPL) is a bulk raw material for polymer and engineering plastics production. The CPL production wastewater contains many toxic substances such as cyclo-hexanone, cyclohexanone oxime, cyclohexane, and benzene. After biochemical treatment, parts of harmful chemicals remain in the sludge, which is regarded as hazardous solid waste. The common treatment for this sludge is incineration after dehydration. However, the moisture content is still high (~70%) after usual dehydration, and incineration requires much fuel, leading to high treatment costs. Herein, the wet oxidation (WO) process was employed as a harmlessness and resource method for the treatment of CPL sludge. The results show the removal rates of total solid (TS) and chemical oxygen demand (COD) can reach 45.3% and 64.6% respectively at 240°C for 1 h with 1 MPa oxygen supply. The organic pollutants were oxidized to small molecular organic acids such as formic acid, acetic acid, and iso-butyric acid, which possess good biodegradability. This study provides an efficient approach for harmlessness and resource treatment of hazardous CPL sludge.
