Targeted interception of membrane foulants in MBR: A straw-microplastic composite adsorbent for effective removal of oil and biopolymeric contaminants from catering wastewater

The membrane bioreactor (MBR) encounters substantial membrane fouling challenges during catering wastewater treatment, attributed to oil content and protein/polysaccharide constituents in soluble microbial products (SMP) and extracellular polymeric substances (EPS) present in the sludge mixture. This is the first study to develop an adsorbent by coupling acidified corn stalk (A-CS) with ultraviolet-aged polylactic acid (UV-PLA) via a silane coupling agent, specifically for alleviating membrane fouling in MBR treating catering wastewater. In the ternary pollutant system evaluation, the adsorbent demonstrated exceptional adsorption capacities of 11071 mg/g for oil, 28.07 mg/g for protein, and 22.51 mg/g for polysaccharide. The adsorption process followed the multilayer adsorption model and was primarily dominated by spontaneous exothermic physical adsorption, with some contribution from chemical adsorption. Implementation of the A-CS/UV-PLA in the adsorption MBR (AMBR) yielded significant operational improvements relative to conventional MBR (CMBR), including a 40 % reduction in transmembrane pressure (TMP) increase rate, a 20.70 % improvement in 24-hour oil removal efficiency, and marked decreases in protein and polysaccharide concentrations in both SMP and EPS during the 100-day operational period. Fluorescence analysis verified the preferential removal of protein-like substances. This approach alleviates membrane fouling while simultaneously achieving resource recovery through "waste-to-waste" treatment, offering a sustainable strategy for treating catering wastewater.