The Characteristics And Mechanism About Degrading Particular Pollutants In The Water With Algal-bacterial Photosynthetic Microbial Fuel Cell In Different Operation Modes

The bioelectrochemical system provides a new technological approach to enhance the removal of pollutants in water.Building a kind of a sustainable and self-sustaining biolelectrochemical system for wastewater treatment is always an important proposition in application research of bioelectrochemical system.But collocating properly operational principle of bioelectrochemistry system with biological degradation characteristics of pollutants can efficiently degrade pollutants,while simultaneously reduce the negative effect of pollutant degradation on bioelectrochemical system.This study is based on the construction of a algal-bacterial photosynthetic bioelectrochemical self-sustaining system,investigated the characteristics and mechanism of nitrogen dyes and denitrification in different operating modes.Using algae and anaerobic sludge from municipal waster as inoculation sources,we constructed a photosynthetic bioelectrochemistry sysem with reversible polarity double algae-bacterial bioelectrodes?Reversible Photo-Bioelectrochemical Cell,RPBEC?,achieving simultaneous degradation of Congo red and power generation in polarity reversion.On this basis,A novel AQDS/Mn/PPy electrode was prepared by one-step electropolymerization method and was used to improve performance of degrading zao dye and electricity generation.The results showed that first decolorize the Congo red by algal-bacterial Photosynthetic Microbial Fuel Cell?MFC?,after that,the anode light reverses polarity to photosynthetic cathode to make the decolorization product further mineralized,finally realized the whole process degradation of Congo red in the single-pole chamber.Compared to the bare electrode RPBEC,the RPBEC with AQDS/Mn/PPy electrodes significantly improved synchronous degradation of azo dyes and electrochemical properties.It demonstrated 77%increases in maximum power and 73%increases in Congo red decolorization rate before polarity reversion,and 198%increases in maximum power and 138%increases in decolorization products mineralization rate after polarity reversion,respectively,which is contributed to the composite electrode accelerate the electron transfer of anode and cathode,thus ehance their electrochemical reaction kinetics.Building a algal-bacterial Photosynthetic Microbial Fuel Cell?PMFC?to remove nitrogen from synthetic high-strength nitrogenous wastewater,which is follow natural day/night cycle of alga and alternately treat dissolved oxyen from algal photosysnthesis and nitrate as electron acceptors,achieving self-sustaining operation for algal-bacterial photosynthetic MFC and denitrification in algal-bacterial cathode.To carry out the experiment,adding ammonia?NH₄-N,314 mg/L?and nitrate?NO₃-N,330 mg/L?to algal-bacterial cathode.During 118h,NH₄-N was removed completely,while the removal rate of nitrate was 68%.The photosynthesis/respiration of alga induced under alternating light/dark cycle provides conditions for maintaining microbial diversity of algal-bacterial cathode.High throughput sequencing results showed there are ammonia oxidizing bacteria,aerobic denitrifying bacteria,anaerobic denitrifying bacteria and autotrophic denitrifying bacteria coexist in algal-bactierial cathodic biofilm,so that nitrogen was removed by multiple ways,including ammonia nitrification of algal photosynthetic oxygen,autotrophicdenitrification with cathode as electron donor,heterotrophic denitrification with dissolved organic matter produce by algal photosynthesis as carbon source and uptake with algal,bacterial metabolism.Beyond that,the research furth studied the effects of the main operation parameter on the performance of denitrification with algal-bacteiral photosynthetic biocathode.The result showed that high concentration nitrogen content is able to promote denitrification by algal-bacterial biocathode,is contributed to the metabolic enhancement of photosynthetic oxygen by algae and synthetic dissolved organic carbon and the growth of algal biomass,thereby facilitating nitrification of NH₄-N,the heterotrophic denitrification of NO₃-N and nitrite nitrogen?NO₂-N?and the absorption of nitrogen by alga.The acidity produced by denitrification and cathode-oxygen reduction can neutralize the acidity of nitrification and proton diffusion,thus reducing the concentration of phosphate buffer.Additional organic carbon can promote growing of alga,and continuesly release photosynthetic soluble organic carbon,in this way,heterotrophic denitrification was enhanced.However,due to the degradation of organic carbon need to consume dissolved oxgen,so the nitrification of NH₄-N was negatively affected to some extent.