| Environmental pollution and energy shortage are the two major challenges in front of us, while the emergence of microbial fuel cells provides a new way to solve these two problems. Because MFCs makes it possible to remove the pollutants of wastewater, and generate power at the same time. So to reduce nitrogen with electricity generation in microbial fuel cells is feasible theoretically.In this experiment, two-Chamber microbial fuel cells(MFCs) with proton exchange membrane(PEM) were constructed to examine the loss mechanisms of ammonia in anaerobic anode, and the factors(temperature, p H and C/N)of affecting ammonia removal were analyzed.The experimental results provided a theoretical basis for the treatment of ammonia wastewater. The result showed that :(1)The microbial fuel cells in which the ammonia was the only electron donor of the anode, were successfully started after 70 days’ domesticated cultivation of sludge.When the MFCs worked, the voltage was 40.3m V, and the removal rate of ammonia in the anode was 72.29%; while the removal rate of nitrate in the cathode was very small,20.42%. The p H of both chambers remained in alkali environment, around 7.20.(2)With ammonia concentrations enhanced from 15.00mg/L to 65.00mg/L, the peak voltage was changed from 28.3m V to 92.9m V. When the concentration of ammonia was 35.00 mg/L, the resistance of MFCs and the maximum power density were 123.07Ω and 109.35 m W/m2, respectively. So ammonia could be used as the substrate in MFCs to generate power.(3)When both nitrate and ammonia existed in the anode, the rate of ammonia removal speeded up, so the anaerobic ammonia oxidation(Anammox) may exist in MFCs. When the concentration of ammonia decreased from 35.00mg/L to 4.71mg/L,ammonia become nitrate and nitrate, 35.64% at least. While 2.12% from anode went into cathode through the proton exchange membrane(PEM). The ammonia losses were caused by biological and physical-chemical factors simultaneously.(4)When temperature changed from 20℃ to 40℃, the trend of removal rate of ammonia and voltage both increased first and then decreased. While the temperature was 30℃, the voltage and removal rate of ammonia reached the maximum at 50.3m V and 77.70%, respectively, which had a large synchronization, and the correlationcoefficient was 0.9708. And it showed that the influence of temperature on the voltage and removal rates were coincident.(5)When p H changed at the range of 7.0 to 8.0(condition of alkaline),the changes of removal rates of ammonia and voltages were very small, and the maximum were13.11g/(m3·d) and 54.3m V, respectively. While p H changed in acid range of 5.0-7.0,the removal rates of ammonia and voltages both achieved the lowest,5.18g/(m3·d) and19.4m V, respectively.It was because the acidic conditions affected the microbial’s survival conditions and restricted the volatilization of ammonia.(6)The addition of organic matter had an important impact on voltages and rates of ammonia removal. As C/N increased from 0 to 1:1, the voltage increased gradually, but the removal rates decreased. In the whole process the removal rates of organic matter could reach almost 100%, while the removal rates of nitrate and nitrate decreased. When C/N was among 0-1:4, the power generations were generated by ammonia; When C/N was higher than 1:4, the power generation was caused mostly by organic matter.When C/N was 1:4, the voltage reached 80.3 m V, and nitrogen removal rate reached 16.73g/(m3?d), which could be used as the optimization in MFCs. |
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