Development of membrane bioreactor using biopolymer recovered from corncob waste for tannery wastewater treatment

This study presents the novel development and application of a cellulose acetate membrane synthesized from corncob waste, an agrowaste, in a submerged membrane bioreactor (MBR) system for treating real tannery wastewater. Corncob-derived cellulose biomaterial was used to fabricate the hollowfibre membranes for the very first time. Phase inversion method was used with N-methyl-2-pyrrolidone (NMP) as solvent and polyvinylpyrrolidone (PVP) as the pore-forming additive. Fourier Transform Infrared Spectroscopy (FTIR) confirmed successful acetylation with characteristic ester peaks at 1736 cm^-1, along with key cellulose backbone features. The membrane was integrated into a lab-scale aerobic MBR treating real tannery wastewater with an average feed COD of 2550 mg/L, TSS of 1080 mg/L, NH₄⁺-N of 162 mg/L, and TDS of 7440 mg/L. COD value decreased up to 856 mg/L during biological degradation process and the permeate had the average COD value of 640 mg/L, achieving overall removal efficiency of 75%. Initially, NH₄⁺-N during acclimation process had dropped up to 141 mg/L and then finally reached the value of 55 mg/L. Membrane flux declined steadily from 26.18 to 3.89 L/m²·h as mixed liquor suspended solids (MLSS) increased from 8000 to 12,000 mg/L. The flux recovery ratio (FRR) after chemical cleaning with 0.5% NaOCl was 49.94% for the cellulose acetate membrane and 74.98% for the PVDF membrane, suggesting that further surface modifications or pretreatment steps may be necessary to enhance antifouling properties of biopolymer-based membranes. To improve the final effluent quality, ozonation was applied to the permeate for 60 min. This advanced oxidation step further reduced COD from 640 mg/L to 220 mg/L and significantly removed residual colour.