Feasibility evaluation of combined electrocoagulation/adsorption process by optimizing operating parameters removal for textile wastewater treatment

In this study, a combined electrocoagulation (EC)/adsorption process was employed to separate highly concentrated organic pollutants dyes from a raw textile wastewater. The removal of chemical oxygen demand (COD), turbidity, color, conductivity, salinity and TDS from a raw textile effluent was experimentally investigated by EC technique, using aluminum electrodes, followed by adsorption of treated wastewater on granular activated carbon (GAC). The main purpose was to investigate the effects of several working parameters such as current density, electrolysis time, adsorbent dose and contact time, in an attempt to achieve higher removal efficiency. Based on EC experiments, the highest rate constant abatements of COD, turbidity and color under optimal operating conditions, that is, -current density of 28.57 mA/cm(2) and electrolysis time of 120 min were achieved respectively at 62.33%, 74.43% and 72.79% using Al electrode. The addition of GAC adsorbent as a second treatment step, under optimal operating conditions, that is, adsorbent dose of 0.75 g/L and contact time of 120 min, reduced pollutants concentrations below admissible legal level. The maximum removal efficiencies of COD, turbidity and color achieved 98.33%, 100% and 98.37%, respectively, by overall combined process. EC/GAC coupling process was not beneficial in terms of conductivity, salt and TDS rejection rates as their percentage removals did not exceed 43.29%, 40.35% and 41.5%, respectively. However, EC followed by GAC adsorption improves efficiently permeate quality of the studied raw textile-effluent, and thus this process combination is reported to produce effluent of reuse standard. The results of this investigation provide important data for the development of a hybrid EC/GAC process to remove significant highly concentrated organic pollutants dyes from raw textile wastewater, using moderate activated carbon dose and aluminum consumption, and thereby, lowering the cost of treatment. -Consequently, EC/GAC combined processes are inferred to be superior to these processes alone.