WET AIR OXIDATION

Wet air oxidation (WAO), involving oxidation at high temperature (125- 320 degrees C) and pressure (0.5-20 MPa) conditions, is useful for the treatment of hazardous, toxic, and nonbiodegradable waste streams. Th e process becomes self-sustaining when the feed chemical oxygen demand (GOD) is about 20 000 mg/L and can be a net energy producer at suffic iently higher feed COD's. All the published information on WAO has bee n analyzed and presented in a coherent manner. Wet air oxidation studi es on pure compounds have been critically reviewed. Mechanism, kinetic s, and structure-oxidizability correlation for WAO of carboxylic acids , phenols, cyanides, and nitriles have been described. The industrial applications discussed include municipal sewage sludge treatment, dist illery waste treatment, black liquor treatment, cyanide and nitrile wa stewater treatment, spent carbon regeneration, and energy and resource regeneration. Waste streams from other sources and some miscellaneous applications of WAO have also been included. Special emphasis is give n to WAO under supercritical conditions (above the critical temperatur e of water) and oxydesulfurization of coal. In addition to the industr ial applications, some other aspects (like various catalysts and oxidi zing agents) of WAO have also been discussed. Recommendations and sugg estions for further investigations have been made.