Poly (methacrylic acid) / starch incorporated low-pressure polyethersulfone (ultrafiltration) membranes for slaughterhouse wastewater treatment intended for reuse

Polyethersulfone (PES) ultrafiltration (UF) membranes were modified with starch and varying concentrations of poly (methacrylic acid) (PMA) and integrated with a granular multimedia (GM) filtration system to evaluate their performance in slaughterhouse wastewater treatment for reuse. Increasing PMA loading (0.5–3 wt%) resulted in smoother, more hydrophilic membranes, with an average surface roughness decreasing from 363 to 66 nm and contact angle decreasing from 69.2 ± 3.6 to 63.4 ± 3.1˚. Although porosity (75.8 ± 6.5%–63.8 ± 4.7%) and water uptake (79.3 ± 1.2%–69.8 ± 3.2%) slightly declined, antifouling and reusability improved markedly, maintaining flux recovery ratios above 90% after 1 cycle and above 80% after 5 cycles. The addition of starch and PMA decreased the pure water flux (133.3–40.7 Lm −2 h −1 ) at 1 bar, and this correlated with a reduction in pore size from 0.021 ± 9.0 × 10 –4 to 0.012 ± 1.1 × 10 –5 µm. The GM pre-filtration achieved up to 95.9 ± 1.8% turbidity reduction, 23.6 ± 0.01% total organic content (TOC) reduction, and 80.9 ± 0.4% chemical oxygen demand (COD) reduction, significantly alleviating membrane fouling. The combined GM-UF system achieved removals of 99.6 ± 0.9% TOC, 91.8 ± 0.2% COD, and 100% turbidity, fats, oils, and greases, producing effluent compliant with South African non-potable water reuse standards. These findings demonstrate the synergistic benefits of starch and PMA incorporation in enhancing membrane antifouling performance and the overall efficiency of the hybrid GM-UF system for sustainable onsite slaughterhouse wastewater reuse.