Synergistic effects of powdered activated carbon (PAC) during initial biofilm formation of the methanogenic consortium on polyurethane foam

Abstract

BACKGROUND: In the unfavorable conditions of anaerobic digestion systems, the attached or immobilized microbial communities used as biofilm are more resistant to being washed out than the suspended biomass. The biofilm formation was determined by the carrier characteristics, considering their physicochemical properties and high availability. This study presented an approach for improving the use of polyurethane (PU) foam as a biofilm carrier for methanogenic consortium. RESULTS:The effect of powdered activated carbon (PAC) on the reactor performance and biofilm formation was apparent during days 0-30. The average chemical oxygen demand (COD) removal, methane (CH 4 ) composition, and CH 4 yield of PACsupplemented reactor (R2) in this period were 71.40%, 82.0%, and 0.3 L CH 4 g −1 COD removed, respectively; these values were higher than those of the control reactor (R1). In addition, a greater amount of biomass was observed on the PU foam of R2 (1.47 g VSS), indicating a higher biofilm formation. Scanning electron microscopy (SEM) analysis revealed that microbial biofilm on the PAC-supplemented PU was also denser than that on the control PU. In addition, fluorescence in situ hybridization (FISH) detected layers of Methanosarcinales and Smithella sp.CONCLUSION: This study demonstrated that PAC supplementation had synergistic effects during initial biofilm formation of the methanogenic consortium by accelerating microbial attachment, preserving biofilm structure, and enhancing methanogenic activity.