• wet air oxidation;
  • catalytic wet air oxidation;
  • oily sludge;
  • COD removal

This work studied the feasibility of treating oily sludge by means of wet air oxidation (WAO) at high temperatures. The effect of the operating conditions on COD removal of the oily sludge, including temperature, the initial COD of the oily sludge, residence time, concentration of catalyst, and O2 excess (OE), was studied. WAO has been proved to be a very efficient technology for the treatment of those residual currents, resulting in destruction efficiencies of greater than 80% of initial COD. Adding a catalyst significantly improved the COD removal. Homogenous catalyst, Ni2+, showed effective removal for pollutants. COD removal was 97.8% in the catalytic wet air oxidation (CWAO) over Ni2+ catalyst. The results proved that the CWAO was an effective pretreatment method for the oily sludge. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 99–102, 2013.