Oxidation of wastewaters

Direct electrochemical reduction and oxidation treatment of pollution involving a mass-free reagent - the electron - is a very attractive idea, because it is a uniquely clean process, as (1) the reduction and oxidation take place at inert electrodes and (2) there is no need to add chemicals. The techniques of cathodic reduction/anodic oxidation of wastewaters containing dyes are relatively new and have drawn the attention of investigators in Japan, China, USA and Russia [55]. 

Beziat, J., Besson, M., and Gallezot, R, Catalytic wet air oxidation of wastewater, 3rd World Congress on Oxidation Catalysis, 1997, pp. 615-621. 

Ollis DF (2000) On the Need for Engineering Models of Integrated Chemical and Biological Oxidation of Wastewaters, Conference Proceedings of the 2" International Conference on Oxidation Technologies for Water and Wastewater Treatment,... 

On the basis of this study, Sudoh et al. [78] proceeded to generate hydrogen peroxide in an acidic solution (1 M H2SO4) for use in Fenton s reagent oxidation of wastewater streams (Fig. 20). The peroxide, produced at the cathode in an alkaline KOH electrolyte, was transferred by electrodialysis to a central chamber, separated by anion exchange membrane (ACLE-5P, Tokuyama Soda, Japan) on the cathode side and a cation exchange membrane (CM-2, Tokuyama Soda, Japan) on the anode side. At a current of 4 A, 2.2 kmol/m of H2O2 was found to accumulate in the cen-... 

Photocatalytic oxidation of wastewater containing dissolved textile dyes is feasible for colour removal. In addition to remove the colour from the wastewater, the photocatalytic reaction simultaneously reduced the COD which suggests that the dissolved organics can be oxidised. These oxidation reactions require air, water, photocatalyst and UV light. The results suggest that the photocatalytic degradation of textile dye may be a viable method for decolourisation and oxidation of organics in wastewater. 

Several laboratory studies have also been realized in gas-liquid-solid reactors. They are concerned with the oxidation of pure liquids (cyclohexane, ethylbenzene, tetralin, cumene, etc...) or of diluted aqueous solutions. In this fiels, the oxidation of wastewater in trickle-bed reactor has been proposed as an alternative to biological purification. 

Park, T., Lim, J., Lee, Y., et al. (2003). Catalytic supercritical water oxidation of wastewater from terephthalic acid manufacturing process, J. Supercrit. Fluid, 26, pp. 201-213. 

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