Wastewater dye destruction using ozone-loaded Volasil™245 in a continuous flow liquid–liquid/ozone system

Volasil™245 (decamethylcyclopentasiloxane), originally developed as a heat exchange fluid, has been found to dissolve 10 times more ozone than does water. Extracting wastewater contaminants to ozone-loaded Volasil™245 is proposed as a means of enhancing reaction kinetics and thus, providing more rapid wastewater decontamination. Using a continuous flow pilot plant, ozone-loaded Volasil™245 contact was applied to dye-contaminated waters. Process kinetics and efficacy have been assessed in terms of colour, COD and TOC reductions, and also in relation to direct ozone gas contact. Design and operating conditions for the prototype Volasil™245 liquid–liquid/ozone wastewater treatment plant are proposed. It was found that counter-current ozone-loading of the solvent is required instead of co-current loading. The dyes used were not extracted into the solvent and expected kinetic enhancement was not realised compared to direct gas/water treatment. Other contaminant chemicals are being studied to assess the process further.