Chemical Wet Oxidation for the Abatement of Refractory Non-Biodegradable Organic Wastewater Pollutants

Abstract

Various chemical wet oxidation techniques to remove toxic non-biodegradable pollutants from wastewater were compared in this work. Techniques applied included catalytic wet air oxidation (CWAO) over active carbon (AC) alone and with hydrogen peroxide (H2O2) as well as wet peroxide oxidation (WPO) without or plus Fe2+ initiator. The oxidation tests were conducted in a Trickle Bed Reactor and a tubular coil reactor at 25–550°C and 10–150 bar. The refractoriness to chemical wet oxidation was investigated for various organic pollutants including phenol, o-cresol, m-xylene, o-chlorophenol, p-nitrophenol, aniline, nitrobenzene, sulfolane and two industrial phenolic wastewater. CWAO over AC destroyed readily phenol, o-cresol, m-xylene and o-chlorophenol at 140°C and 9 bar of O2. More refractory aniline, p-nitrophenol, and particularly sulfolane and nitrobenzene, were tested with either H2O2 promoted CWAO or WPO at higher temperatures. The use of Fe2+ initiator was attempted to reduce the treatment severity of WPO. In a final step, the wet oxidation techniques were tested on the industrial effluents to obtain treatment efficiencies under field conditions.