Evaluation of Textile Wastewater Treatment Using Combined Methods: Factor Optimization via Split Plot RSM

The increase in the consumption of textile products as well as the use of dye compounds has increased the pollution of the effluent in these industries. Discharge of this wastewater without proper treatment can cause groundwater pollution, poisoning, and serious health effects. Dyed pollutants contain benzene rings and are more resistant to conventional biological treatment such as activated sludge. In this study, two combined processes in series were applied for the treatment of towel dyeing wastewater. An experimental design was used to optimize the process. In a batch reactor, the Anodic Oxidation (AO) process and the Electro-Fenton (EF) were compared using four anodes and cathodes. The performance of AO method in dye removal and COD reduction was better than EF method. A good agreement is attained between the predicted value using experimental design and actual results. The correlation coefficient of dye removal, energy consumption, and COD was achieved 0.966, 0.997, and 0.900, respectively. The results showed that under optimum operating conditions of AO process (voltage=6.5 V, t= 6 min, and pH =9.5) decreased 97% of dye index and 61% of COD amount. This condition was obtained by consuming 6.7 kWh of energy per cubic meter of wastewater (0.07 $/m3). The output of the optimal AO entered the Reverse Osmosis (RO) system, in the last step. TDS of effluent was reduced 98% in the membrane and also the COD decreased from 980 to 13 ppm under 6 bar pressure