Removal of Congo Red dye from its aqueous solution using natural coagulants

The textile dyeing industry consumes large quantities of water and produces large volumes of wastewater from different processes in dyeing and finishing processes. The low-cost, easily available naturally prepared coagulants like Surjana seed powder (SSP), Maize seed powder (MSP) and Chitosan as an ideal alternative to recent expensive coagulant methods for Congo Red (CR) dye removal has been investigated in this study. Various process parameters like pH, coagulant dose, flocculation time and temperature and also its optimization were exploited. The maximum percentage CR removal was found to be 98.0, 94.5 and 89.4 for SSP, Chitosan and MSP, respectively, at pH 4.0, coagulant dose of 25 mg/l, flocculation time 60 min and temperature of 340 K. The Sludge Volume Index (SVI) and turbidity were calculated for these parameters including process optimization. SSP found more preferable for CR removal and Chitosan was a better coagulant, which corresponds to SVI than the other coagulants investigated.