Treatability studies on textile effluent for total dissolved solids reduction using electrodialysis

Treatability study of effluent from textile common effluent treatment plant (CETP) was performed in a laboratory scale three compartments electrodialysis system. The studies were done in batch, batch recirculation and continuous mode of operations in a constant current mode to optimise the current density, residence time and flow velocity to reduce the total dissolved solids (TDS) content of the effluent to meet discharge limit as well as for reuse in the textile processing units. Optimised condition was obtained based on the studies conducted with sodium chloride solution (7500 mg/L) and sodium sulphate solution (5000 mg/L). The applicability was checked with textile CETP effluent sample, which had TDS of 6730 mg/L. Sand filter was used as a pretreatment system. The limiting current density for the used pair of membranes for the treatment of textile CETP effluent was found to be 6 mA/cm2. Operating current density of 3.6–4.8 mA/cm2 is recommended for the treatment of effluent form textile CETPs having TDS around 7000 mg/L for the reduction of TDS.