Optimization of continuous electrocoagulation-adsorption combined process for the treatment of a textile effluent

Abstract

Experimental setup: (a): Real schematic of pilot, (b): 3D scheme of pilot/ 1: tank with untreated effluent, 2: variable frequency pump, 3: Electrocoagulation reactor, 4: adsorption reactor, 5: mechanical stirrer, 6: tank for sedimentation, 7: acrylic container of the suspension of clay, 8: mechanical mixer of the suspension of clay, 9: 12 Volt peristaltic pump, 10: control panel of current supplier, 11: 10 parallel iron electrodes. • The full continuous combined process based on electrocoagulaion-adsorption on crude clay is a very efficient process for textile effluent decontamination. • The achieved removal efficiencies of color, COD and TSS were respectively 96.87%, 89.77% and 84.46%. • The achieved treated effluent fulfill the Tunisian standards of rejected wastewater and could be used in preparation process or in irrigation. • Treatment efficiencies were enhanced at neutral pH range, slow effluent flow rate, high voltage and high adsorbent suspension flow rate. The aims of this study is to design and optimize the functioning of a full continuous combined process based on electrocoagulaion-adsorption on crude Tunisian clay to treat a real textile effluent. The clay characterization shows that the used clay is a rich-smectite clay. The response surface methodology (RSM) technique based on Box-Behnken design (BBD) was used to optimize the process. At optimum conditions which are initial pH solution of 8.24, effluent flow rate of 0.5 L·min −1 , voltage of 70 V, and added suspension of clay flow rate of 100 ml·min −1 the achieved color, chemical oxygen demand (COD) and total suspended solid (TSS) removal efficiencies were respectively 96.87%, 89.77% and 84.46% with 0.75USD·m −3 as total cost. The additional laboratory experiments at optimum conditions agree with the predicted results, which confirm the accuracy and the capability of RSM to predict results in the defined space. Finally the designed process could be a good eco-friendly alternative to treat and reuse wastewater in industrial process with reasonable cost.