Comparative investigation of PFS and PAC coagulants with activated carbon in cellulose microfiltration systems for treatment of real printing ink wastewater

Abstract

Printing Ink wastewater (PIW) generated during printing machine cleaning, ink formulation, and paper processing is a significant environmental concern because of its hazardous chemical composition. A complex combination of pollutants is generated as a result of printing ink operations, including toxic chemicals such as heavy metals (lead, cadmium, and chromium), volatile organic compounds (VOCs), resins, solvents, and synthetic dyes. If printing ink wastewater (PIW) is not handled properly, it poses a grave concern to the health of humans as well as the environment. As a result of contaminated water entering drinking water sources and agricultural fields, harmful chemicals can accumulate in the human either directly or indirectly through direct consumption, skin contact, or food consumption. A number of serious health issues can result from exposure to these compounds, including dermatitis, respiratory problems, organ damage, particularly to the liver and kidneys, as well as even cancer. In order to avoid these consequences, modern methods of treating printing ink wastewater (PIW)are needed, such as chemical precipitation, electrochemical advanced oxidation, and hybrid systems. This study examines a hybrid treatment system that combines coagulation with adsorption for the effective removal of these contaminants from actual industrial wastewaters. In order to achieve coagulation, 30 mL polyferric sulfate (PFS) and polyaluminum chloride (PAC) were individually used as pretreatment agents, followed by adsorption with powdered activated carbon (AC) and a cellulose microfiltration step. During an interval of four minutes (60, 90, 120, 150 minutes), both coagulants were tested at pH 6.5, which provides optimal coagulation efficiency by maintaining the coagulants' stability and reactivity. The results demonstrated that PAC had higher treatment efficiency compared to PFS, achieving COD and TSS removal rates of 98 %, BOD₅ and TOC elimination rates are 97 %, and 94 % respectively after 150 minutes of settling. PAC has been shown not only to enhance floc formation but also to enhance particulate and dissolved organic matter removal. Results indicate that continuous-flow systems in industrial settings have a great deal of potential for scaling. It is recommended that in the future, work be focused on assessing the reusability of the adsorbent, conducting a cost-benefit analysis, and developing efficient methods for large-scale implementation.