Integrated MF–UF Treatment of Poultry Pre-Chiller Wastewater: Pollutant Removal, Fouling Behavior and Hydraulic Resistance Analysis

Poultry pre-chiller wastewater contains high concentrations of organic matter, suspended solids, proteins, and lipids that promote severe membrane fouling. This study investigated fouling development in an integrated microfiltration–ultrafiltration (MF–UF) system treating poultry pre-chiller wastewater, focusing on hydraulic performance, resistance evolution, fouling mechanisms, and membrane surface characterization. This study provides an integrated assessment of treatment performance and fouling mechanisms in a sequential microfiltration–ultrafiltration (MF–UF) system treating real poultry pre-chiller wastewater. MF was performed using a 0.1 μm polyvinylidene fluoride membrane, followed by UF with a 60 kDa polysulfone membrane under different transmembrane pressures. Fouling was evaluated through permeate flux monitoring, resistance-in-series analysis, Hermia–Field modeling, ATR-FTIR spectroscopy, and chemical cleaning. The MF stage achieved up to 97.8% turbidity removal, providing effective pretreatment for UF. The integrated MF–UF process removed 99.81% of chemical oxygen demand, 99.82% of turbidity, and 61.90% of total solids. Increasing transmembrane pressure increased the initial permeate flux but accelerated fouling, resulting in progressive flux decline. Resistance analysis identified fouling resistance as the main contributor to hydraulic resistance, while Hermia–Field modeling indicated pressure-dependent fouling behavior during MF, shifting from complete pore blocking at 0.5 bar to cake filtration at 1.0 bar, whereas UF showed contributions from multiple fouling mechanisms. ATR-FTIR confirmed protein- and lipid-rich foulants, and chemical cleaning revealed the coexistence of reversible and irreversible fouling. UF at 1.0 bar provided the best balance between permeate productivity and fouling control.