CFD Simulation of DAF processing for removal microplastic in different flotation solution

Microplastic particles floating in rivers, lakes and seawater are one of the factors that threaten human health and the environment. In this study, the process of dissolved air flotation (DAF) to remove microplastics from various wastewaters was simulated by the computational fluid dynamics (CFD) method. First, a solution with a plastic particle concentration of 0.2 g/L was injected at a flow rate of 200 mL/min. Then, a microbubble water with a water-to-microbubble volume ratio of 4:1 was injected at a flow rate of 300 mL/min and the simulated results showed that the kinematic and distribution characteristics of the plastic particles and microbubbles were in good agreement with the experimental results. Based on the simulation system to analyze the behavior of particles in flotation solutions, the flotation performance was evaluated by varying the concentration of NaCl solution from 0 to 12 g/L and the pH value of 10^-2 M salt solution from 4 to 9. The calculation results showed that the flotation performance improved with increasing NaCl concentration and pH, and the concentration of NaCl had a greater effect. These results provide some basic information for designing industrial wastewater treatment processes for the removal of microplastics in wastewater.