A combined hydrocyclone - electrocoagulation treatment for different types of industrial wastewater

Every year, a large amount of mineral processing wastewater is discharged from various industries into the environment which is considered a challenging task not only because of its large volume, but more importantly, its hazardous components, while its reuse as feedwater without proper treatments causes great harm to the final product of these industries. Cost-effective methods are required to treat a wide range of industrial wastewater in a diverse range of conditions. In this study, a combined hydrocyclone-electrocoagulation system is tried to treat the wastewater for industries with high water consumption and high pollutants such as paper industry, iron and metal forming industry, and marble industry. The effects of the hydrocyclone operational parameters, such as feed inlet pressure and diameter, vortex finder diameter, apex diameter, and feed solids content, were investigated. In the case, wastewater of paper industry, the following optimum conditions $(P = 4.5$ bar, $D_o = 15.8 mm, D_u = 6 mm, D_i = 4 mm and c_s = 2.3%)$ were achieved. An overflow of about 90.58% water recovery and 21.45% solid at 75.92% separation efficiency was obtained. The results showed that the hydrocycloneelectrocoagulation treatment has efficiently treated the three different types of industrial wastewater. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solid (TS), total suspended solids (TSS), colour and turbidity, were reduced sharply and met the effluent discharge or reuse standards. Also, compared with the hydrocyclone-treated wastewater, the hydrocyloneelectrocoagulation-treated wastewater was found to be more enhanced