Coagulation of Wastewater Containing Polyethylene Terephthalate (PET) Microplastics by Using Ferric Chloride, Aluminum Sulfate and Aluminum Chlorohydrate: A Comparative Study

This study investigated the efficacy of different coagulants, namely ferric chloride and aluminum sulfate at a concentration of 1.95 g/L, and aluminum chlorohydrate at a concentration of 2.1 g/L, in removing microplastics from plastic recycling facility wastewater under different pH conditions. The results showed that the presence of microplastics in wastewater was 76% in the form of fragments, followed by films and fibers in smaller amounts. The size of these microplastics varies, with a dominant size range of 251-500 μm. At pH 6, ferric chloride and aluminum sulfate were able to remove 75% and 90% of the microplastic abundance, respectively, by adding a dose of 1.95 g/L. However, the highest removal efficiency was obtained by adding a dose of 2.1 g/L Aluminium chlorohydrate at pH 8. These findings underscore the importance of selecting suitable coagulants and optimizing treatment operational conditions based on the type and size distribution of microplastics present in the wastewater system.