Sludge decrement and electricity generation of sludge microbial fuel cell enhanced by zero valent iron

According to the shortage of global energy, the energy consumption of excess sludge treatment is too high. Abundant organics can't be utilized effectively in sludge, causing waste of resources. Sludge microbial fuel cell (SMFC) has been used to treat excess sludge. This technology can transfer organics in sludge to electricity directly, achieving the stabilization and recycling of excess sludge. But the efficiency of organics utilization and electricity generation in SMFC is low. Based on the above issues, we constructed a single chamber SMFC with scrap iron added to anode (FeSMFC) to investigate the effect of iron on environmental conditions, electricity generation and sludge decrement. Due to strong reduction of zero valent iron (ZVI), oxidation reduction potential (ORP) decreased and pH increased slightly in FeSMFC. At the end of one cycle, sludge decrement was remarkable. Three-dimensional excitation-emission matrix fluorescence spectrum (3DEEM) indicated that iron-carbon galvanic cell changed the composition of sludge and enhanced the utilization of organics in FeSMFC. Volatile suspended solids (VSS) and total chemical oxygen demand (TCOD) removal efficiency of FeSMFC was 66.20% and 44.74% respectively, 24.48%, 178.40% higher than SMFC without ZVI (NSMFC). The reaction time of FeSMFC was 21 days shorter than NSMFC. Above all, scrap iron added to anode in SMFC is a method to improve the reaction rate and efficiency of sludge decrement in situ without additional energy consumption. It is also cost saving.