| The development of human society depends on the supply and exploitation of energy. However, the shortage of energy and its environmental pollution after burning, has become the big problem for the world, so it was very urgent to speed the exploitation and utilization of biomass energy. Microbial electrochemical system was unique system capable of converting the chemical energy of organic waste including low-strength wastewaters and lignocellulosic biomass into electricity or hydrogen. It was considered as an environmentally friendly technology, and has good prospect. But for a long time, due to the high price of Pt catalyst in the cathode and poor performance of electricity production, these limit its practical application. So if we can successfully use a waste as the form of oxidant as cathode electron acceptor, it could greatly improve the environmental and economic benefits of BES. And the current density and voltage of existing BES system were too low to meet the daily needs, so how to effectively use the energy generated from BES was also an important and difficult problem.Based on the analysis above, this paper studied BES using heavy metal ions to product electricity, in order to decrease the cost of cathode and improve the output. The research had studied electricity production performance of the CEM-MFC using Cr(Ⅵ) and AEM-MFC using Cu2+ as cathode electron acceptor respectively, and also the trend of voltage, power density and resistance of system under different p H and the initial concentration were invesigated. And the cathode efficiency of BES was detected. Based on solving the problem that ion migration will reduce the anode microorganism activity, it further proposed using microbial desalination fuel cell to enhance the performance of electricity production, and corresponding analyzed the desalination effency and cathodic efficiency. The paper also revealed cathodic reduction product of Cr(Ⅵ) and Cu2+. Becauase of the low output of BES and high adsorption capacity of CDI under low energy consumption, the paper studied the performance of using MFC as power resource to drive CDI treating wastewater containing copper under different conditions.For existing MFC used heavy metals for electricity production with high cost of proton exchange membrane, the paper proposed to replace AEM with PEM in the MFC using Cu2+ and replace CEM with PEM in the MFC using Cr(Ⅵ) for electricity production, respectively. The results showed that p H greatly affect the efficiency of electricity and Cr(Ⅵ) removal. In biological cathode MFC using Cr(Ⅵ) as electron acceptor, when the cathode p H was 6.8 ~ 7.0, with the initial Cr(Ⅵ) concentration of 80 mg/L, it could achieve the maximum current density 250 m A/m2 and the Cr(Ⅵ) removal rate 99%, which were 200 times as that using abiotic cathode under 7.0. Through high-throughput sequencing analysis, it was found the proportion of Acinetobacte reach 23.5% in the level of genus. Acinetobacter had the high tolerance of Cr(Ⅵ), and had the ability of restoring Cr(Ⅵ). The output voltage rise obviously when the biofilm existed in the cathode, which illustrated that Acinetobacter had electrochemical activity for Cr(Ⅵ) reduction. These results indicated that MFC using heavy metal ions for electricity production could enlarge application of BES.On the basis of the research on the MFC, the paper further studied MDC using Cu2+ and Cr(Ⅵ) as electron acceptor could enhance the performance of electricity production. It was put forward new type microbial desalination cell as FMDC containg the copper waste. The results showed that when the external resistance 10 Ω, the initial Cu2+ concentration of 800 mg/L, FMDC could obtain the maximum current density 2.0 A/m2. The three chamber MDC using Cr(Ⅵ) as electron acceptor also get the electricity production, desalination and Cr(Ⅵ) reduction function. When using Cr(Ⅵ) as cathode electron acceptor, p H had the greatest effect on the current density and desalination. Under p H 2.0, the initial Cr(Ⅵ) concentration of 100 mg/L, it could get Cr(Ⅵ) removal rate of 75.1% with the current density of 760 m A/m2 and desalination rate 2.1 mg/h at the same time.Compared the internal resistance of the MFC and the MDC systems under the same operating conditions, it was found MFC was more suitable as power driving CDI to treat wastewater containing Cu2 +. Compared to fixed 0.8 V DC power supply, the adsorption effect by a single MFC was slightly lower. However, the connection of MFC by series or parallel, can significantly improve the adsorption performance of CDI. The Cu2+ adsorption capacity of CDI drived by three MFC can reach more than 22 mg/g, which improved 20.4% and 22% than that with one MFC as power.This paper studied the characteristics of BES system using Cr(Ⅵ) and Cu2+ for electricity production. The main function was producing electricity, simultaneously accompanied with desalination and heavy metal removal process. And to explore the feasibility of BES system to produce electricity driving CDI electrode to adsorbe Cu2+ from wastewater, it could achieve good treatment effect, and finally get the aim of the waste recycling by BES system. |
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