Treatment of regenerated papermaking wastewater by sequencing batch moving bed biofilm reactor and kinetics study

Abstract This study evaluated the use of three Sequencing Batch Moving Bed Biofilm Reactors (SBMBBR) with Mutag biochip 30™ (MB) carriers for treating regenerated papermaking wastewater. The reactors operated at filling ratios of 15 % (MB15), 30 % (MB30), and 45 % (MB45). Biomass stabilized after 30 days, reaching 2.26 g/L, 4.01 g/L, and 5.58 g/L, respectively. The process parameters of the reactors were optimized using Response Surface Methodology (RSM). Under conditions of a C/N ratio of 21:1, an aeration rate (AR) of 2.65 L/min, a hydraulic retention time (HRT) of 9 h, and a 45 % filling ratio, the chemical oxygen demand (COD) removal efficiency of the wastewater achieved the highest value of 68.28 ± 2.03 %, with the average effluent COD reduced to approximately 170 mg/L while ammonia nitrogen and total nitrogen were below 10 mg/L and 15 mg/L, meeting the discharge standards for recycled paper mill wastewater in China. Kinetic analysis using an improved Stover-Kincannon model showed good fitting (R 2 > 0.93) and the highest degradation rate (U max ) of 2.6413 g/Lday in the MB45 reactor. These results support SBMBBR’s potential for treating papermaking wastewater and addressing challenges in other industrial wastewater treatments.