44 / 2023-04-30 22:14:22

SIMULTANEOUS ENHANCEMENT OF TREATMENT PERFORMANCE AND ENERGY RECOVERY USING SEWAGE SLUDGE BIOCHAR AS SUBSTRATE IN CONSTRUCTED WETLAND COUPLED WITH MICROBIAL FUEL CELLS

sewage sludge,biochar,constructed wetland,energy recovery,MICROBIAL FUEL CELL

Constructed wetland coupled with microbial fuel cells (CW-MFCs) are a promising technology for sustainable wastewater treatment. However, the performance of CW-MFCs has been constrained by the limited electron transfer among traditional non-conductive materials. Here, sewage sludge biochar (SSB) with optical conductivity was used as the CW-MFC substrate to improve treatment performance and energy recovery. The results show that SSBs significantly facilitate COD removal. Meanwhile, the maximum power density was increased to 44.64 mW/m² with SSBs due to the higher cathode potential (358.2 mV±48.8) and lower inner resistance (900.00 Ω) compared to the traditional gravel-integrated CW-MFC (13.23 mV±8.6, 2057.14 Ω). The conductive SSB accelerates the electron transfer in the air cathode to enhance the air cathode potential. At the same time, a typical exoelectrogen Geobacter was found enriched in the anodic zone to enhance the electroactive scope and decrease the inner resistance in SSB-integrated CW-MFC. Further, the conductivity of SSB is proportional to the doping of pyridinic and graphitic nitrogen (Fig.1). Thus, the SSB could enhance both the treatment performance and the energy recovery of CW-MFC, in which the nitrogen doping of SSB plays an important role.  To our knowledge, this is the first study to use SSB as the substrate in CW-MFC. The findings of this study are beneficial for wastewater treatment and the recycling and reuse of sewage sludge.