Efficient Elimination of Organic Liquid Wastes: Wet Air Oxidation

Wet air oxidation is ideally suited to liquid wastes which are too dilute to be incinerated and too refractory to be handled by chemical or biological oxidation. This process relies on high temperature (470°–600° K) and pressure (2–20 mPa) conditions for oxidation of the organic substances by molecular oxygen in the liquid phase. Several types of industrial wastes, mainly paper‐mill black liquors, biological sludges, and acidic organic wastes, have been tested for oxidation in a batch reactor. This research provides evidence for the high efficiency of the wet air oxidation process for the transformation of most of the pollutants to carbon dioxide. An average removal efficiency of 98% was obtained. As acetic acid is the main intermediate appearing during oxidation of the heavier organics, the study of the behavior of sodium acetate under treatment conditions enabled the most efficient oxidation conditions to be determined for numerous wastes. The various data available are compiled in a general chart which makes a quick determination of the working conditions possible for any indexed waste. Moreover, it has been established that a continuous process usually leads to a net production of energy. It is believed that this research is the first step in the design of a large‐scale wet air oxidation unit.