Biodegradability enhancement of textile dyes and textile wastewater by VUV photolysis

Photo-degradation and biodegradability have been studied for three different families of non-biodegradable textile dyes (Intracron reactive dyes, Direct dyes and Nylanthrene acid dyes) and a textile wastewater, using VUV photolysis. Ninety percent of color removal of dye solutions and wastewater is achieved within 7 min of irradiation. Biological oxygen demand (BOD) was found to increase during discoloration process while chemical oxygen demand (COD) decreased. The biodegradability index (BOD5/COD) increases up to 0.40 for most of the dye solutions when total discoloration is obtained. It implies that VUV photolysis tends to enhance the biodegradability of dye containing solutions. Thus, this technique could be used as a pre-treatment step for conventional biological wastewater treatment. (C) 2002 Elsevier Science B.V. All rights reserved.