Ceramic Membrane Ultrafiltration for Biogenic Elemental Sulfur Recovery: Performance Optimization and Fouling Analysis

Biological sulfate removal in mining wastewater generates recoverable elemental sulfur particles that require efficient downstream separation. This study evaluated ceramic membrane ultrafiltration for separating biogenic sulfur from membrane biofilm reactor effluent's supernatant using 50-, 150-, and 300-kDa membranes under varying transmembrane pressure and crossflow velocity. All conditions achieved high sulfur rejection (95.9%-98.1%), whereas normalized flux declined to 0.06-0.26, showing that hydraulic performance was controlled by fouling rather than particle retention. Response-surface analysis identified the 50-kDa membrane as the best compromise between rejection and fouling resistance. Cyclic filtration with cleaning showed partial reversibility, with flux recovery of 86.1%, 83.1%, and 107.5% after three cycles. Interval-averaged Hermia analysis indicated mixed/sequential fouling, with cake/gel filtration providing the best global fit and intermediate blocking remaining competitive. Cleaning reduced the estimated membrane-area penalty factor from 3.8× to 16.7× to approximately 1.8× to 4.4×, supporting design based on sustained fouled flux.