Anode Modification And Configuration Improvement Of PSMFC On PAHs Biodegradation And Electricity Production

Plant Sediment Microbial Fuel Cell(PSMFC)is an emerging technology in recent years,the PSMFC can remediate contaminated sediment and simultaneously generate electricity.The purposes of this current study are to enhance the mass transfer and efficiency of remediate sediment contaminated with polycyclic aromatic hydrocarbons(PAHs)by using PSMFC.In this current study,the relationships among plant roots and anode position were optimized,the SMFC and PSMFC were constructed by anodes modified with carbon nanomaterials,A new configuration plant sediment microbial fuel cell(New-PSMFC)for increasing the mass transfer of sediment was designed.We study the power generation of PSMFC,the removal of PAHs,microbial activity and community.The obtained results could provide theoretical basis and technical guidance for SMFC and PSMFC in practical application.Through exploring the effect of relationships between plant roots and root oxygen loss at anode position on the performance of traditional PSMFC,it was found that the relationships determined the electricity generation.The results showed it was not optimal structure when the plant roots and anode closely arranged,because the oxygen concentration was 26.5 μmol/L in the rhizosphere that not beneficial to electricity generation.In general,it had little effect of excrete oxygen on electricity generation when the plant roots were located 2.5 cm above the surface of the anode,the root exudates could provide substrate for anode in electricity generation process,simultaneously,the output voltage was higher than the roots and anode closely 2～3 times.In sandy sediments with low organic matter,root oxygen excretion is the main controlling factor of the circadian rhythm of electricity production.The electricity generation and adsorption of phenanthrene and pyrene were all enhanced in SMFC with anode modified by carbon nanomaterials,which was more beneficial to generate electricity and adsorb organic matters.In this study,graphene(GNs),graphene oxide(GO)and carbon nanotubes(CNT)were used to modify the anodes of SMFC and PSMFC systems.In the study of SMFC,the carbon nanomaterial modified anode improved the PAHs removal ability of SMFC,high concentration CNT modified anode groups has the highest removal within sediment 1 cm near the anode surface,and the removal rate of phenanthrene and pyrene reaches 91.55% and 88.34%,The control group was less than 50%.High throughput sequencing results indicate that enrichment of Geobacter,Anaerolineaon,Desulfobulbus and Pseudomonas on the anode biofilm of the different modified methods.Similarly,the PSMFC with anode modified by carboxylated carbon nanotubes showed 200 m V increase in electricity generation and 1.63 times in phenanthrene removal,which revealed the anode modified by carboxylated carbon nanotubes and plants synergistically made it better for the SMFC performance.The mass transfer of PSMFC is another important factor limiting its repair efficiency and range A New-PSMFC with plant-driven mass transfer was constructed in this study,that improve degradation of organic pollutants.The mass transfer and microbial activity of New-PSMFC were improved,the output voltage was increased,the startup speed was accelerated,and the voltage drop from decreasing substrate concentration was slowed down in PSMFC.Moreover,the output voltage in NewPSMFC was about 1.5 times than these results in PSMFC at later stage.Simutaneously,the enzyme and microbial activity,and the removal of PAHs away from the anode were all increased in the whole system.The removal rate of phenanthrene and pyrene were 66.33% and 64.32% on 82 d,which was 1.5～2.0times compared with the removal rates in the tradition PSMFC and SMFC.Through the redundancy analysis,the removal process of phenanthrene and pyrene in the sediment was related to enzyme activity of microorganisms than the organic concentrations.