Investigating the efficiency of coagulation and flocculation process in wastewater treatment of paper and cardboard recycling industry

In addition to the large volume, the generated wastewater in paper and cardboard recycling industry contains various organic compounds and dyes. Treatment of these wastewaters is difficult due to the diversity of contaminants and the complexity of their chemical structure. This study aimed to investigate the efficiency of the coagulation and flocculation process by the new mixture of coagulants for wastewater treatment in one of the paper and cardboard recycling industries. To determine the efficiency of the coagulation and flocculation process in removing the parameters, including turbidity, colour, TSS, and COD, the Jar Test was used in laboratory conditions. By changing the variables, such as pH, coagulant type (PAC/MgCl2, PAC/Polymer, MgCl2/Polymer, MgCl2/PAC, PAC/MgCl2/Polymer), coagulant dose, and polymer dose, the optimal conditions were determined. Based on the results, the highest turbidity removal efficiency was achieved for the combination of coagulant and coagulant aid (PAC/MgCl2/Polymer) at pH 11. According to the experiments, the highest removal efficiency of turbidity, colour, COD and TSS were95.43%, 25.16%, 16.16%, and 83.33%, respectively. According to the obtained results, the coagulation and flocculation is a suitable method to remove turbidity and suspended solids in the paper and cardboard recycling industry wastewater. However, in order to remove more colour and COD, additional treatment is required.