Studies on Decolorization of Textile Dyeing Rinse Wastewaters in Solar Photocatalytic Reactors

Abstract

Two ‘Water Fountain Solar Photocatalytic Reactors’ of trapezoidal and circular configurations were developed and the influence of flow rate on solar photocatalytic decolorization of simulated textile dyeing rinse wastewaters was studied in the range of 1.5L h^-1 - 12 L h^-1. A catalyst dosage of 1.0 g L^-1 was adopted for two types of Titanium dioxide viz. P25 TiO₂ and an indigenous IS TiO₂ (manufactured in India confirming to the specifications of Indian Standards (IS) TiO₂ (BIS 1991)) and the studies were carried out at the natural pH of the wastewaters. The samples were collected at 15 min interval for analysis of color. A flow rate of 6.0 L h^-1 was considered as the optimum flow rate and further treatability studies on three batches of industrial textile dyeing rinse wastewaters (RWWI, RWW2 and RWW3) were carried out at this flow rate in the reactor of trapezoidal configuration using IS TiO₂. During the treatability studies, percent decolorization varied with variation in light intensity and more than 90% decolorization was observed at light intensities greater than 20 W m^-2. Hence it could be concluded that for tropical countries, the decolorization of textile dyeing wastewaters using IS TiO₂ in this novel solar photocatalytic reactor has proved to be a more suitable treatment technique.