Degradation studies of reactive black 5 and textile industry wastewater by combined photo-fenton and biological oxidation

Abstract

In the present study, the photo-Fenton process was used for the pretreatment of Reactive Black 5 dye and industrial textile wastewater with the objective of improving its overall biodegradability and determining the degree of increased oxidation followed by biological process. Some parameters, like pH, temperature, initial concentrations of Fe2+ and H2O2 and the use of natural or artificial light were evaluated aiming to find the optimal conditions to promote the efficient degradation of the dyes. The experimental results showed that the photo-Fenton process run under solar light was the most effective. The degradation observed is 91% with optimal conditions of pH=4, H2O2=4.4 mM and Fe2+ =0.15 Mm with 90 mins Process under UV light alone for photo-Fenton process. The optimal time to stop the pretreatment process and introduce the effluent to the biological system was 20 min. The biodegradability of the process was checked by BOD5/COD ratio. Results obtained from this work indicated that the photo-Fenton process could be a suitable pretreatment method in reducing toxicity of pollutants and enhancing biodegradability of textile wastewaters treated in a coupled photochemical–biological system.