| Microbial fuel cell(MFC) is a facility that converts the chemical energy into electricity using microbe as catalyst, purifying waste water at the same time. When facing serious environmental pollution and water shortage issues, MFC is a new method to achieve sewage resource and sustainable development. In order to explore the performances of simultaneous nitrification and denitrification process in the cathode of MFC, a dual-chamber aeration bio-cathode MFC which the effluent of anode first flow to heterotrophic denitrifying pool then flow to cathode room was combined with the A/O biological nitrogen removal process to treat synthetic low C/N ratio wastewater. The main conclusions of the experiments are as the followings,During the start-up of simultaneous short-cut nitrification and denitrification the nitrite accumulation and ammonia-oxidizing bacterial enrichment were achieved in the cathode of the MFC after a one-time feeding cultivation for 15 days. The reactor was converted to a continuous operation mode. 21 days later, the simultaneous short-cut nitrification and denitrification was successfully accomplished in the cathode of the MFC. The concentrations of ammonia, nitrite and nitrate of the cathode effluent were 0.3mg/L, 15.9 mg/L and 0.6 mg/L respectively. The conversion rate of ammonia to nitrite was higher than 95%, and more than 50% nitrogen was removal by autotrophic denitrification. The removal efficiency of COD was higher than 85%. Combining the simultaneous short-cut nitrification and denitrification process with MFC, oxygen obtained electrons in the aerobic cathode and a high pH value environment can be created, consequently, nitrogen removal and electric energy recovery can be achieved at the same time. The simultaneous short-cut nitrification and denitrification process can be strengthened.With the resistance increasing, the concentrations of ammonia and nitrite changed slightly in cathode effluent while the concentration of nitrates increased. The removal rate decreases with the increase external resistance.The highest removal efficiency of total nitrogen was achieved when the resistance was 5Ω and the highest coulombic efficiency was achieved in both anode and cathode when the resistance was 25Ω.The coulombic efficiency is 2.5% in the anode and 7.1% in the cathode.By changing the concentration of influent ammonia-nitrogen, the performance of nitrogen removal and power output can reach the best when the concentration was at 240 mg/L. With the concentration of influent ammonia-nitrogen increasing, nitrogen removal and power output efficiency decreased. In this experiment the best concentration of influent ammonia-nitrogen is about 240mg/L. |
