The Use of an Alum-Based Coagulant “Bucochem” for the Cleaning of Natural Water from Styrene/Divinylbenzene Microplastics

Volodymyr Kulish, Igor Winkler , Sergiy Boruk

The efficiency of an alum-based coagulant BUCOCHEM in removing styrene/divinylbenzene microplastic particles sized between 400 and 500 µm from water has been investigated. It was found that the coagulant promotes better sedimentation and compaction of the plastic particles, ensuring the formation of a dense, more stable, and more easily removable sediment layer. 0.1 wt % of the coagulant leads to a decrease in the height of the polymer sediment layer by 14% after 48 hours, as compared to the coagulant-free sedimentation. Furthermore, the former sediment appears more compact and stable.
Additionally, the coagulant led to a faster initial sedimentation of microplastic particles. Although the rate of sedimentation decreased when the coagulant was added, this effect was not crucial for the efficiency of cleaning.
The optimal content of BUCOCHEM was found to be 0.05-0.075 wt%. At this concentration, three-dimensional coagulant flocs can form, adsorb microplastic particles, and trap them in a compact and stable precipitate layer, which effectively resists secondary resuspension.