| Environmental pollution and energy shortages are two major problems facing the world today.Electroactive microorganisms can oxidize organic matter into carbon dioxide,protons and electrons in microbial electrolysis cells(MECs).The electrons are collected by the anode and then passed through an external circuit to the cathode.The generated protons and electrons combine to form hydrogen in the cathode.Therefore,MEC is a new type of organic wastewater/waste treatment technology that is expected to achieve waste resource utilization and high productivity.However,the lack of engineering electrode materials and low hydrogen production efficiency severely limit the further development of MECs.Based on this,this paper selects the titanium electrode with excellent biological and chemical stability.In-situ formation of TiO2 nanotubes and sludge pyrolysis gas were used to modify titanium electrode.These methods significantly increases the specific surface area and biocompatibility of the titanium electrode,thereby increasing the amount of microbial adhesion on the surface of the electrode,and finally obtaining superior current output performance.In addition,the use of negative pressure regulation to inhibit the production of methane.Therefore,the efficient recovery of hydrogen is achieved.Finally,the system is used to treat food waste,to investigate its resource utilization capacity of actual organic waste and the value of engineering application.Main contents and results of this dissertation are as follows:1?Preparation and performance evaluation of biocompatible titanium-based metal anodes.Firstly,TiO2 nanotubes are formed in situ on the surface of the electrode.The titanium electrode having large specific surface area,high biocompatibility and excellent crystal structure is obtained by heat treatment in different gas atmospheres.Thereby,the amount of microbial adhesion on the electrode surface is significantly increased.The electron transfer rate between the electrode and the biofilm is also increased.The current output performance of the electrode is improved at last.The electrode after heat treatment under hydrogen atmosphere has the best current output performance and the current density can reach 22.69 ± 0.18 A m-2.However,there are still problems such as complicated modification steps,expensive modification costs,and secondary pollution.Secondly,the modification of titanium electrode by sludge pyrolysis gas can also improve its specific surface area,hydrophilicity and biocompatibility.After modification by sludge pyrolysis gas at 1100 ?,the electrode obtained the best current output performance of 15.80 A m-2.In addition,the electrode has good stability as measured by a constant current method.Most importantly,the modification step of this method is simple and effective.The preparation methods of the two electrodes were comprehensively selected from the aspects of electrode preparation process,preparation cost,electricity generation performance and carbon footprint.Finally,the titanium electrode modified by sludge pyrolysis gas was selected as the electrode material for MECs engineering application.2?Study on negative pressure regulation and high efficiency hydrogen production strategy of single-chamber MEC.The generation of methane in a single-chamber MEC is inhibited by the method of negative pressure regulation.Therefore,the hydrogen recovery,energy recovery and electron recovery are improved.The hydrogen production rate obtained under negative pressure is 7.72 ± 0.06 L L-1 d-1,which is 5 times that under normal pressure.In addition,the hydrogen recovery and energy recovery obtained under negative pressure were 12 times and 1.5 times higher than that under normal pressure,respectively.At the same time,the growth of methanogens was also effectively inhibited under negative pressure regulation.Therefore,the single-chamber MEC with excellent hydrogen production performance has high engineering application potential.3.Application of single-chamber MEC to treat food waste and efficiently produce hydrogen.Taking the food waste as a substrate,the utilization of the waste was realized by single-chamber MEC.The hydrogen production obtained from the MEC and the anaerobic fermentation reactor using food waste as a substrate was examined.The hydrogen yield obtained by the single-chamber MEC was 500.8 mL H2 g-1 DFW,which was much higher than the 48.4 mL H2 g-1 DFW of the anaerobic fermentation reactor.At the same time,the hydrogen production rate of MEC is 4.86±0.38 L L-1 d-1,which is much higher than that of other MEC reactors using complex substrates.The MEC has a hydrogen recovery up to 96%and an electrical energy recovery of 238.7±5.8%.In addition,the food waste treated by the MEC has a degradation rate of solid waste up to 64.9%,which is higher than 55.9%of anaerobic fermentation treatment,indicating that the method can effectively reduce the volume of food waste.In summary,the single-chamber MEC controlled by negative pressure based on sludge pyrolysis gas modified titanium anode has high hydrogen recovery and energy recovery,which has a wide application prospect in the treatment of organic waste. |
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