Piezoelectric Disinfection of Water Co-Polluted by Bacteria and Microplastics Energized by Water Flow

The presence of microplastics in the aquatic environment, as a vector for colonization and proliferation of harmful microorganisms, brings a great challenge for water disinfection. This study investigates piezoelectric inactivation of Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Enterococcus faecalis (E. faecalis) on the surface of microplastics under water flow by using molybdenum disulfide as piezoelectric material. The piezoelectric sterilization capacity was evaluated by comparing different polymer types and sizes of microplastics, in which 4.5 log10 CFU mL–1 E. coli cells were reduced for 50 μm PVC particles at a water flow speed of 80 rpm in 20 min. Piezoelectric disinfection was dependent on water flow rates and treatment time and was feasible in riverine water containing authentic microplastics and in a spiral reactor that simulated natural water flow. Reactive oxygen species were generated via water flowing over the piezoelectric material, resulting in the inactivation of bacteria on the surface of microplastics. This study highlighted the great potential of water flow as a “green” source of energy and elucidated a new opportunity of piezoelectric disinfection in aqueous media containing microplastics.