Performance Evaluation of Tile Wastewater Treatment with Different Coagulants

Introduction: The objective of this study was to investigate wastewater quality and the efficiency of removal of wastewater contaminants produced by a tile factory by using ferric chloride, ferrous sulfate, ferric sulfate, aluminum sulfate (alum) and poly-aluminum chloride (PAC) coagulants. Materials and Methods: This is an applied study. A composite sample was taken of the wastewater production line of the factory. Wastewater characteristics including pH, EC, temperature, turbidity, TSS, TDS, TS and COD were measured in accordance with the standard methods. In the next step, the jar-test experiment was used to investigate the effect of changing doses of coagulants (0.15, 0.2, 0.25, 0.3, 0.35 g/L) and pH values (7, 9, 11) on the removal of contaminants. The effective dose and optimal pH were thus selected and the best coagulant was later determined. Results: The optimum pH of 11 was obtained for removal of contaminants by ferric chloride, ferric, ferrous sulfate and 7 for alum and PAC. The optimum concentration of the five coagulants was obtained at 0.3, 0.3, 0.3, 0.25, 0.25 g/L respectively. PAC, with the turbidity removal EC, TSS, TS and COD removal of 99.92%,17.74%, 99.93%, 89.8%, 75% respectively, had best performance at lower doses and alum, ferrous sulfate, chloride, ferric and ferric sulfate were placed in the next rankings. Conclusion: Among the five studied coagulants, PAC is the most effective coagulant, and then alum, ferrous sulfate, ferric chloride and ferric sulfate are placed. Given that PAC is more expensive than other materials, care should be taken to select the most appropriate coagulant.