Membrane Aerated Biofilm Reactors for Thermomechanical Pulping Pressate Treatment

A comparative study on the treatment of thermomechanical pulping (TMP) pressate between thermophilic (55 degrees C) and mesophilic (30 degrees C) membrane aerated biofilm reactors (MABRs) was conducted under different cycle lengths (CLs) for over 114 days. The performance of the MABRs was evaluated in terms of soluble chemical oxygen demand (COD) removal and biofilm detachment. With a total influent COD of 3,700-4,100 mg/L, the soluble COD removal efficiency of thermophilic MABR (40-65 %) was slightly lower than that of mesophilic MABR (50-80 %) under different CLs. The level of effluent suspended solids (ESS) in treated effluent of the thermophilic MABR was generally higher than that of the mesophilic MABR, suggesting a more significant biofilm detachment from membrane surfaces in the thermophilic MABR. The performance of COD removal improved at the time five to ten days after each significant biofilm detachment. The results suggest that MABR is a promising technology for TMP pressate treatment and biofilm thickness control is important for achieving better performance.