| Landfill leachate is a kind of refractory organic wastewater with high ammonia concentration. It has been a hot research topic in treatment and resource utilization field. MFC is a rapid development of new technology, it combines the biological and electrochemical method and can directly converts pollutants into electricity by microbial degradation which realizes the removal of pollutant and electricity generation. The treatment and utilization of landfill leachate using MFC will become a new research topic.In this paper, through the construct of two bottles microbial fuel cell, study the effect of different operation conditions such as batch feeding and continuous feeding on organic matter, nitrogen removal efficiency and electricity generation using MFC. And also study the removal pathways of anode nitrogen in this process. At the same time, in order to improve the efficiency of nitrogen removal study the feasible of MFC anode anaerobic ammonium oxidation and nitrogen removal. The results of this study are as follows:1. Study the electricity generation, nitrogen and carbon removal under different influent concentrations of fresh leachate in MFCThe fresh leachate (COD concentration:16000 mg/L) as the anode substrate, it gradually increase the leachate proportion(10%-100%) to enrich the electricigens. The output voltage showed a trend of first increased and then decreased. When the leachate volume fraction is 60%(COD concentration:9040 mg/L),it reached the maximum output voltage(421.30 mV),and the maximum output power density is 1.10 mW/m3.But the maximum columbic efficiency was only 21.31%,suggested that the organic consumption for the production of electricity proportion was low. The removal efficiency of COD is presented first increased and then decreased, the maximum is 90.60%;and the removal rate of ammonia nitrogen decreased in this process, the maximum was only 59.13%.The results showed that the high concentration of leachate in the efficiency of ammonia nitrogen and carbon removal is less than low concentration. The increase of the concentration was harmful to the pollutant removal rate.2. Study the electricity generation,nitrogen and carbon removal in continuous treatment of high concentration of fresh leachate in MFCThe high concentration of fresh as the anode substrate, when MFC continuously treated it(COD concentration:16000mg/L),the result showed:when residence time for 3-6 d, it can achieve sustainable electricity generation and NH4+ removal rate is relatively higher. When the residence time for 7 d with batch feeding, the maximum output voltage was 354.7 mV, and the removal rate of COD and NH4+-N was 49.51% and 6.84% respectively. And with continuous feeding, the maximum output voltage was 362.20 mV, the removal rate of COD and NH4+-N was 54.52% and 19.73% respectively. After statistical analysis, the removal rate of COD and NH4+-N were significantly different(P value was 0.022 and 0.014),but there was no significant different in output voltage(P value was 0.071).Although the effect of inlet mode on the maximum output voltage is not obvious, but the continuous feeding can realize electricity generation last for a long time(6 d).Further, study the removal pathways of anode NH4+-N, found that 75.34%of the anode NH4+-N was diffused to the cathode, another part was transformed and removed by other forms. The results showed that the anode NH4+-N has not been effectively removed in this process, it was just transferred to the cathode.3. Study the electricity generation and nitrogen removal performance of MFC anode anaerobic ammonium oxidationIn order to improve the nitrogen removal efficiency, this paper study the MFC anode anaerobic ammonia oxidation electricity generation and nitrogen removal performance when the artificial wastewater and mature leachate was used as the anode substrate.T he results showed that when using artificial wastewater, the output voltage showed the trend of first increased and then decreased. And when the concentration of NH4+-N is 240 mg/L, the output voltage, NH4+-N,NO2-,TN removal rate simultaneously reached the maximum,153.40 mV,81.32%,84.13%,78.62% respectively, and the maximum power density is 130.71 mW/m3.The trend of mature landfill leachate output voltage is similar to the artificial wastewater, but the concentration of NH4+-N which reached the maximum output voltage is different. When the concentration is 200 mg/L, he output voltage,NH4+-N,NO2--N,TN removal rate simultaneously reached the maximum,206.80 mV,65.82%,89.41%,66.73% respectively, and the maximum power density is 237.62 mW/m3.Obviously,the electricity generation performance of mature leachate was superior to the artificial wastewater. The reason may be that the mature landfill leachate conductivity is higher than that of artificial wastewater, and the transfer capacity of electron is also higher. It made the activation resistance to low. But the nitrogen removal efficiency was exactly the opposite. From the ratio of comsumed NO3-N to consumed NH4+-N and ratio of produced NO3--N to consumed NH4+-N, we can see the artificial wastewater vary little in amplitude. The result indicated that the stability of artificial wastewater reaction is better than the leachate. The reason may be that the leachate contained organic substances, and the this substances had a certain limited on the anaerobic ammonium oxidation.Overall, this study innovatively combined anammox to the treatment of actual landfill leachate by MFC and meanwhile suggests that this systems is able to remove ammonium by anammox. Even though its ammonium removal rate and bio-electrogenic capacity still remains to be improved, this technology would be promising in leachate treatment and clean energy production industries... |
PDF Full Text Request