Effects of polystyrene microplastics on the breakthrough behavior of dissolved organic matter in carbon filtration column

The breakthrough of dissolved organic matter such as humic acid (HA) during water filtration processes is a critical factor contributing to the formation of disinfection by-products. The presence of emerging pollutants, such as microplastics, may influence this process. This study investigates the impact of polystyrene microplastics (PS-MPs) on the breakthrough of HA in granular activated carbon (GAC) columns. The presence of PS-MPs, along with their abundance and UV aging, significantly affects HA's breakthrough. Higher abundance of PS-MPs enhances HA's breakthrough by occupying adsorption sites on GAC, while UV-aged PS-MPs, due to increased hydrophilicity and surface roughness, reduces the promoting effect of PS-MPs on HA breakthrough. Orthogonal experiment revealed that flow rate, HA concentration, ionic strength, and abundance of PS-MPs influence HA's breakthrough, with flow rate being the most significant factor. Zeta potential and hydrodynamic diameter analyses showed that UV-aged PS-MPs, with more negative charges and smaller sizes, had a higher tendency to penetrate GAC, freeing up adsorption sites for HA. A backpropagation (BP) neural network model was trained to predict HA removal and optimization using a genetic algorithm (GA) further improved prediction accuracy. This study provides insights into PS-MPs & HA interactions and presents a reliable tool for predicting GAC filter performance in the presence of PS-MPs.