Integrating sequencing batch hybrid membrane bioreactor with ozonation for treatment of tissue paper wastewater

This study assessed the performance of a sequencing batch hybrid membrane bioreactor (SB-HMBR) coupled with ozonation for the treatment of tissue paper wastewater. The SB-HMBR was operated for 90 d with a cycle time of 8.5 h under two aeration intensities, corresponding to specific aeration demand per membrane area (SADₘ) of 0.32 and 0.16 m 3 m⁻ 2 h⁻ 1 . The permeate obtained under the lower aeration regime was further subjected to batch ozonation (3 and 4 g O 3 h − 1 ). Despite substantial variations in influent COD between Phase I (417 mg L − 1 ) and Phase II (279 mg L − 1 ), with BOD₅ values of 46 and 45 mg L − 1 , the reactor maintained stable performance, achieving COD removals of 91% and 78%, respectively, with complete BOD₅ removal. Ammonium removal decreased from 75% to 65% under reduced aeration, reflecting the sensitivity of nitrification to oxygen limitation, while phosphorus removal remained low (30–44%). Phenolic compound removal and color reduction ranged from 70 to 78% and 65–74%, respectively. UV–vis analysis indicated that chromophore attenuation resulted from the combined effects of biodegradation and membrane separation, with no significant changes in removal patterns under reduced aeration. Ozonation significantly improved permeate quality, achieving color removal of 90–92% and phenolic compound reduction of 47–48%. However, soluble COD exhibited transient increases, indicating partial oxidation of macromolecules into more soluble intermediates. Overall, the SB-HMBR coupled with ozonation provided an effective strategy for tissue paper wastewater treatment, ensuring stable performance and efficient effluent polishing under reduced aeration conditions.