Study On Anodic Iron Reduction Bacteria Enhanced OsMFC Treatment Of Pig Wastewater And Pollution Resistance Of Membrane

Microbial Fuel Cells（Microbial Fuel Cells,MFCs）can treat organic wastewater and bio-generate electricity.It is a green and sustainable sewage treatment process.However,traditional MFCs processes still have low electricity production efficiency,serious proton-exchanged membrane pollution,and expensive.Based on the fact that forward osmosis membranes（FO membranes）have higher proton flux and better conductivity than conventional proton exchange membranes,this study uses forward osmosis membranes instead of traditional cation exchange membranes to construct a forward osmosis microbial fuel cell（Forward Osmosis Microbial Fuel Cell,OsMFC）.The reactor uses the electrostatic force between the electrons and the contaminants on the FO membrane surface to slow down the pollution of the forward osmosis membrane and the solute reverse osmosis phenomenon,and at the same time strengthen the iron-reducing bacteria in the system,so that it can not only produce a large amount of Electrons also degrade contaminants on the surface of the FO film.Therefore,in this study,a forward osmosis microbial fuel cell was constructed,and iron-reducing bacteria after separation and enrichment were added to the anode to treat the source separation pig wastewater（COD:1000-1200 mg/L,NH₄⁺-N:280-350 mg/L,TP:18-28 mg/L）,the wastewater treatment efficiency,power generation efficiency,FO membrane water flux and FO membrane cleaning and recycling during the operation of the OsMFC system were studied.The main research conclusions are as follows:（1）Screening and research of iron-reducing bacteria.Screening and enriching iron-reducing bacteria from the stable OsMFC system.After analyzing the physical and chemical characteristics,it is found that glucose is the best carbon source for the bacteria under different carbon source conditions.The dehydrogenase activity in the system is related to Fe（Ⅱ）The accumulation shows a positive correlation,which can reflect the activity state of iron-reducing bacteria in the system to a certain extent,in the order of glucose>sucrose>sodium acetate.It shows that the best carbon source condition for the iron-reducing bacteria obtained by separation and enrichment in this experiment is glucose,so glucose is used as the anode carbon source of OsMFC in subsequent experiments.（2）Start the experimental research.The pollutant removal efficiency under the four circulation rate conditions is 100 m L/min>87.5 m L/min>60 m L/min>30 m L/min,and by comparing the operating performance of the OsMFC system under different concentrations and different draw solutions,it is found 0.5 mol/L Na Cl is most suitable as the draw solution for this experiment.Therefore,it can be concluded that the OsMFC used 0.5 mol/L Na Cl as the draw solution in this experiment,and the circulation rate was 100 m L/min.（3）Research on the operating effect of OsMFC based on iron-reducing bacteria.Add purely cultured iron-reducing bacteria to the anode chamber of the successfully started OsMFC system.The average stable output voltage of the system within 50 days is 840.55±15.15 m V,and the average removal rates of COD and total phosphorus are 98.82±0.14%and 99.28±0.11%,respectively.At this time,the maximum power density of OsMFC is 1.276 W/m³.In the system with iron-reducing bacteria,the conductivity of the catholyte decreased from 45.31 m S/cm to19.85 m S/cm,and the amount of Na⁺reverse osmosis increased from 6.40 g/（m²·h）to 10.79g/（m²·h）.The flux of the FO membrane only decays from 3.20LMH to 1.83LMH.On the contrary,without iron-reducing bacteria OsMFC system,the conductivity of the catholyte only decreased from 45.29 m S/cm to 30.38 m S/cm,and the amount of Na⁺reverse osmosis increased from 12.23 g/（m²·h）to 18.19 g/（m²·h）),the flux of the FO membrane decreased from 3.14 LMH to 1.54 LMH.It can be concluded that adding iron-reducing bacteria to the successfully started OsMFC anode chamber can not only increase the system’s electricity production,but also inhibit the system’s reverse solute osmosis flux and FO water flux attenuation.（4）FO membrane fouled,cleaned and reused.The surface of roughness and confocal laser scanning microscopy（CLSM）of the FO membrane after 7 months of operation of the OsMFC found that the surface of the FO membrane was mainly biologically contaminated.Then the FO membrane was regenerated by Na Cl O,EDTA and physical cleaning.It was found that the output voltage of the OsMFC system during the stable phase of the reactor was 450.55±15.45m V,350.15±5.55 m V and 325.10±3.25 m V,respectively.The removal efficiency of COD was restored to 93.0±0.85%,91.0±0.55%,91.0±0.35%,and TP was removed.The efficiency recovered to 94.5±0.75%,92.5±0.78%,92.4±0.64%.After Na Cl O chemical cleaning,the FO water flux can be restored to 63.12%,after physical cleaning,the membrane flux will be restored to 44.68%,and after EDTA chemical cleaning,it can be restored to 57.45%.Since Na Cl O can restore a higher operating effect after cleaning,it is further confirmed that the surface of the FO membrane is mainly biologically fouled.Research on the cleaning and reuse of the FO membrane has found that the fouling of the FO membrane is mainly a reversible pollution.