Abstract

Membrane contactor technology offers significant potential for ammonia (NH<inf>3</inf>) recovery from wastewater. However, its long-term efficiency presents a critical challenge due to membrane fouling. This study investigates the fouling behavior and performance decline of polyvinylidene fluoride (PVDF) hydrophobic membranes during prolonged operations, focusing on identifying key fouling mechanisms and developing a predictive model. A series of nine-day experiments using synthetic wastewater were conducted to evaluate the effects of foulant type and concentration, acid stripping temperature, and total solid content on membrane performance, quantified by the overall mass transfer (K<inf>OV</inf>). Protein-based foulant (e.g., albumin) induced more severe fouling than carbohydrate-based ones (e.g., alginic acid), owing to stronger hydrophobic interactions with the PVDF membrane surface. The fouling process exhibited a three-stage decline in K<inf>OV</inf>: initial stability, rapid decrease, and eventual stabilization near the minimum. Elevated acid stripping temperatures (35 °C) reduced fouling by diminishing adhesion and particle aggregation, while silica particles improved short-term stability but led to agglomerate formation in protein-rich conditions. A Gompertz-based growth model was developed to predict K<inf>OV</inf> decline over time, showing strong agreement with experimental data (R² = 0.96).