wastewater treatment

coagulation

reactive dyes

textile

Utilization and management

Biological and chemical treatment

Reuse of wastewaters

Coagulation processes

The basic aim of our research was to reduce water consumption in the dying process in the textile industry. This study evaluated the treatment efficiency of combined process of chemical coagulation and electrocoagulation on the synthetically produced dyes C.I. Reactive Yellow 145 and C.I Reactive Red 194. The wash-off liquor generated during the dyeing process was decolorized by adding a mixture of alum and chitosan, followed by electrocoagulation and reused for the wash-off of dyes. Fabric color was analyzed by wash fastness, rubbing and crocking experiments. The combined treatment process was proven to be very effective in decolorizing both dyes by 99.1% and 96.15%. The color difference values of standard (dyed in fresh water) and batch samples for both dyes were 0.53 and 0.35, which is within the acceptable limit (≤1.0). The wash fastness test indicated a range of 4-5 for both standards and batch samples. In the case of water quality parameters, a decrease in pH values was observed after treatment; however, an increasing trend was seen in cases of COD, TDS and EC. While these parameters do not affect the color of the fabric in dying process, this study concludes that the combined treatment of chemical and electrocoagulation is very efficient for decolorizing dye wastewater. Reuse of treated wash-off wastewater is suitable not only for reducing water consumption but also reducing wastewater generation in the textile industry. Hence this treatment option will improve overall water efficiency of the textile industry.