| Microbial fuel cell(MFC)is a novel technology for wastewater treatment as its capacity of converting the chemical energy stored in wastewater into electricity directly within the presence of electrochemically active bacteria.However,MFC is still far away from the commercialized application due to its limitation of low power density,high construction cost and lack of scaling-up technologies.In order to achieve the key technologies about scaling-up MFC,this thesis has studied the electrode materials and cathode preparing process which were suitable for large-size MFC,design and optimization of MFC configuration,MFC stack technologies and fast start-up technologies.Meanwhile,a novel technology composed of MFC and other existed wastewater treatment process was put forward and studied for both energy production and wastewater treatment.This study optimized the cathode preparing process and improved its hydraulic pressure tolerance.The new cathode also had a good scalability because its performance was decreased by 8.7%when its size was increased from 200 cm2 to 2400 cm2.Carbon brush was the most suitable anode material for large-size MFC on account of electric benefit.A 6 L-MFC was used to study the influence of the ratio of cathode area and anode area on power production and the results showed that the maximum power density was around 80 W/m~3 when the ratio was 0.3?0.8,while the maximum power density was decreased to 30 W/m~3 when the ratio was 1?3.Aerated and nonaerated multi-electrode MFC stack and multi-cell MFC stack were developed with the utilization of different cathode structure and oxygen supply method.Result showed that the maximum power density of aerobic multi-electrode MFC stack was 29.2%higher than that of nonaerated MFC stack.However,its recovered energy was no sufficient to offset the energy consumption of aeration,so nonaerated multi-electrode MFC stack was better than aerated considering energy balance.Multi-cell MFC stack was configured and achieved a maximum power density of 69.4 W/m~3 which was 4.4 times higher than that of aerobic multi-electrode MFC stack,meanwhile the constructed cost of multi-cell MFC stack was 58%lower than that of unaerated multi-electrode MFC stack.This result confirmed that multi-cell stack technology was most suitable for scaling-up MFC.To accelerate the formation of electrogenic biofilm in compact MFC,a new method was raised by cyclic voltammetry(CV)scan on MFC.Result showed that CV could improve the adsorption of electrogenesis on the anode material at positive potential and enhance the growth rate at negative potential so as to decreased the start-up time.Comparing to the MFC started-up with an external resistance of 1000 ?,the MFC with CV scan of 24 h reduced the start-up time by 71.4%from 420 to 120 h,and increased power density by 21.5%from 31.1 to 37.8 W m-3.In order to build the mature nitrifying bacteria biofilm in MFC within a short time,electrogenic biofilm was first formed and then nitrifying biofilm was formed upon the existed biofilm.The new inoculation technology only costed 16 days to build mature nitrifying biofilm which was 58%shorter than that of one-step inoculation method.After inoculation,the MFCs could generate a maximum power density of 53.3 W/m~3 and simultaneously removed 94 ± 1.3%of ammonia with slaughter wastewater as the substrate.A pilot scale MFC stack of 1 m~3 was constructed and studied for cosmetic wastewater treatment.The MFC stack achieved a stable COD removal efficiency of 85.3 ± 3.8%and a maximum power density of 0.5 W/m~3 due to the limitation of low conductivity and complicated components of cosmetic wastewater.A group technology of MFC and flocculation was put forward for the first time to treat with swine wastewater and removed 99.1%of ammonia,96.6 ± 0.2%COD with the effluent COD of 90 ± 1 mg/L and generated a maximum power density of 37.5 W/m~3.The analysis of energy benefit between MFC and flocculation process showed that the combined technology created a net benefit of $ 0.026/m~3,which provided an effective way to treat swine wastewater. |
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