Reasearch On Optimization Of Plant Microbial Fuel Cell And Its Microbial Community Structure

Plant microbial fuel cell is a technology that put plants into cell system, and its rootexudates produced in photosynthesis as electrode microbial electron donor thus getsustainable renewable electrical energy. In order to further improve the PMFCtechnology and the system efficiency or reduce the cost of the research reactor, weoptimize the design, inoculum, plants of reactor, explore the effect factors of PMFCpower generation performance and the electrode surface function of the microbialcommunity structure analysis.We discussed effect of different kinds of inoculum on MFC system startup andelectrical activity on the basis of reactor construction and optimization design. Reactoroperate with1g/L sodium acetate as substrate, respectively take Domestic wastewateraerobic treatment of water samples, Domestic wastewater anaerobic treatment of watersamples，Soil, sediment as inoculum. Maximum output voltage of the reactor forAERO(0.493V), SOIL (0.485V), ANAE (0.508V), SEDI (0.514V). the reactor withSonghua river sediment as inoculum get the highest power density of557.85mW/m~2when the load resistance of250, the current density is0.167mA/cm~2, followed by soil(490.65mW/m~2), AERO(451.30mW/m~2), ANAE(444.19mW/m~2). The curve of cyclicvoltammetry show higher electrochemical activity between-0.8V~0.2V and the highestcoulombic efficiency of29.2%when Songhua River sediment as the inoculum.The finalanode biofilm reactor for high-throughput sequencing and analysis of bacterialcommunities. Through the above analysis, and ultimately determine the Songhua Riversediment microbial fuel cell as inoculum.Power density increases with light when PMFC operated under three differentintensity light (0.5W/m~2,3.2W/m~2and6.1W/m~2) and a constant temperature of25℃,phosphoric acid buffer solution concentration was25mM. The most power density was97.21mW/m~2(6.1W/m~2), the other were64.74mW/m~2(0.5W/m~2)、69.36mW/m~2(3.2W/m~2).COD were152.8g/L,158.6g/L,276.8g/L, its change tendency and the powerdensity is consistent.Light intensity increasing effects of plant root exudates increasedsand COD thus power density change.We studied the influence of temperature on PMFC power generation performanceinfluence under a the fixed light intensity (6.1W/m~2) and buffer concentration(25mM).The maximum power density at25℃was93.62mW/m~2, maximum power density for20℃was89.28mW/m~2, maximum power density for30℃was76.66mW/m~2.At low temperature, the power density increases as the temperature change and is nolonger rise until to the appropriate temperature, then fall as the temperature will continueto rise. Considering the polarization curve measurement, we determine25℃isa suitableoperating temperature of plant microbial fuel cell. COD were240g/L,224g/L,336g/L, and is the same with power density change trend, that COD is the direct cause of thepower density. This explains the the temperature change will affect photosynthesis androot secretion of organic matter concentration changes.The experimental setting the reactor1-plants+vermiculite (PLANT), reactor2-plant+sediment (P+S), reactor3-sediment (SEDI) and the original plant root samples(ROOT),and extraction of the anodic microbial DNA after reactor operation stability,high-throughput sequencing to study the functions of flora.Results show that the anode ofmicrobial community structure in a plant microbial fuel cell reactor source frommicrobial enrichment of inoculum and plant root microorganism.The primarymicroorganism were Proteobacteria, Acidobacteria, Bacteroidetes, Chlorobi.