Abstract
Water treatment residual (WTR) is a by-product after settling of suspended particles and colloids by alum in drinking water treatment plants. The reuse of cement kiln dust (CKD) and WTR wastes for treatment purposes is a good solution to remove the dye, chemical oxygen demand (COD) and heavy metals from the textile wastewater. A batch adsorption experiment was performed to evaluate CKD and WTR at different rates, on COD adsorption, color and heavy metals from the textile wastewater. The amount of COD adsorption increased with the addition of CKD and WTR, but the highest adsorption was obtained at 2 h. COD adsorption on CKD was successfully fitted to both Langmuir and Freundlich isotherm models. The maximum adsorption of Langmuir was higher with the addition of WTR (100.0 mg g(-1)) than CKD (14.3 mg g(-1)). Heavy metals in wastewater treated by WTR or CKD were below Egyptian and United States Environmental Protection Agency irrigation guidelines. In this study, the addition of alum to WTR at 200 mg L-1 was effective in the removal of turbidity, color and COD from textile industrial effluents compared to 500 mg L-1 of WTR only. Therefore, WTR and alum can be used as an effective and low-cost adsorbent for the removal of inorganic and organic pollutants from textile wastewater.