Coupling membrane processes with wet air oxidation for the remediation of industrial effluents

Abstract

Membrane processes (ultrafiltration, membrane bioreactor, reverse osmosis) are relevant for the remediation of wastewater as they generate large volumes of high-quality permeate. However, the remaining concentrates are highly polluted and require further treatment. Membrane concentrates are sufficiently concentrated to undergo a highly efficient wet air oxidation treatment to degrade refractory molecules. Wet air oxidation was performed on five industrial membrane concentrates with varying organic pollutants: bilge wastewater, landfill leachates, a complex industrial effluent, pharmaceutical sludge and dairy wastewater. The results showed three categories: (i) a low effect of the anoxic heating period and significant effect of oxidation duration, (ii) a significant effect of both the anoxic heating period and duration and (iii) an outstanding effect of the anoxic heating period and low effect of oxidation duration. The best removals were achieved at 300 °C, with total organic carbon removals between 75 and 98% and chemical oxygen demand removals between 82 and 99%, along with complete removal of fluorescent footprints. The coupling of membrane processes and wet air oxidation was proven to be robust and flexible for a wide variety of membrane processes and pollutants. A mass balance on the treatment path, including membrane permeate and wet air oxidation outlet, was calculated to assess discharge feasibility. This research demonstrates the potential of the hybrid process for effectively treating membrane concentrates and generating a safer outlet.