The Optimization Study Of Desalination In Mustard Tuber Wastewater By Microbial Desalination Fuel Cell(MDC)

Microbial Desalination Cell(MDC)is a new Microbial fuel Cell technology developed in recent years,which can realize synchronous electricity production,salinity removal and pollutant removal.It had confirmed the MDC has a better removal effect of salinity to the NaCl solution in early studies,this experiment replaced by high salt concentration Mustard Tuber Wastewater.we had build the MDC with 3 rooms to study the effect of the width of salt chamber and the type of cathode on the electrochemical performance?Salinity removal and pollutant removal effect of MDC system.In the end16S rRNA gene sequencing technology was used to identify and analyze the dominant bacteria of anode and cathode.The main conclusions have been made as follows:(1)MDC constructed with Mustard Tuber Wastewater,can generate stable current output.In terms of electricity generation voltage,electrode material group with carbon felt,carbon brush and carbon cloth batteries,carbon brush group had the maximum voltage,reaching 708 mv.The performance of carbon paper and carbon felt group were similar.There was no significant difference in the full-cycle voltage peaks of the three groups with a width gradient of 3cm,6cm and 9cm,which were all within 700±5 mV.The 0.1 mol/L group in potassium ferricyanide group on the whole cycle voltage peak voltage was the largest,670 mV,followed by 0.05 mol/L group and 0.025 mol/L,which was 650 mV and 582 mV,respectively,while water cathode group was special,it was only 244 mV when start success,but after nine cycles,there was an obvious growth,voltage up to 450 mV,which related to its water cathode into biological cathode.In terms of power density,the maximum power density of electrode material group was Carbon felt group up to 3.51 W/m~3;The width of salt chamber group was 3cm,up to 5.42W/m~3.The maximum power density of the potassium ferricyanide group was 7.04W/m~3(0.05 mol/L).In the water cathode group,due to the cathode transition,the maximum power densities at 0h-1000h and 1000h were 0.379 W/m~3 and 2.63 W/m~3respectively,with a gap of nearly 7 times.(2)MDC long cycle operation had good desalination effect on the Mustard Tuber Wastewater.Carbon felt of electrode material group had the best effect,the electrical conductivity decreased by 74.78%,and the removal rate of TDS was 73.91%.The narrower salt chamber width had the better desalting effect.The conductivity of the 3cm group decreased by 75.67%and the TDS removal rate was 73.98%.As for the cathode group,the lower the concentration of potassium ferricyanide was,the better the desalting effect had.The reduction rate of conductivity in the 0.025 mol/L group was 90.01%,and the removal rate of TDS was 90.58%.The water cathode group had the best desalting effect in all the experimental groups,and the conductivity and TDS values decreased by91.15%and 90.64%.(3)the maximum reduction rate of organic matter in all groups of anode Chambers was basically above 80%.The reduction rate was related to the electrochemical performance of the battery.The better the electrochemical performance is,the higher the reduction rate will be.The removal rate of ammonia nitrogen in the material group and the salt chamber width group was basically about 70%,and that in the cathode group was related to the type of cathode,and that in the water cathode group was the best,reached94.6%(4)In this experiment,16S rRNA gene sequencing was performed on the anode and anode biofilm microorganisms of MDC in the 0.1mol/L potassium ferricyanide group after 1000h of water cathode.The results showed that the shannon-weiner Index was basically the same as 4.52,4.31 and 4.66 respectively,indicating that there was no significant difference in the community distribution uniformity among the three groups.There was a significant difference in Simpson Index,which was 0.072,0.042 and0.024 respectively,indicating that the number of species in the three groups decreased successively.The dominant bacteria of anode biofilm in the 0.1mol/L potassium ferricyanide group were proteobacteria,Euryarchaeota,Bacteroidetes Chloroflexi,Firmicutes,etc.(phylum level).Methanosaeta,VadinHA17,Geobacter,etc(generic level).In the water cathode group,the dominant bacteria of cathode biofilm are proteobacteria,Chloroflexi,Firmicutes,Actinobacteria,and pondertomycetes,etc.(phylum level).Anaerolineaceae,Pseudomonas,Bacillus,etc.(genus-level)In the water cathode group,the dominant bacteria of the anode biofilm were proteobacteria,Euryarchaeota,Bacteroidetes Chloroflexi,Firmicutes,Synergistetes,etc.(phylum level).Methanosaeta,VadinHA17,Methanosarcina,Anaerolineaceae and so on(genus-level).In this paper,for the first time,MDC was applied to the desalting treatment of Mustard Tuber Wastewater and achieved satisfactory desalting effect.In addition,synchronous electricity generation and partial pollutant removal were realized in the desalting process,It provided a new idea for the treatment of pickle wastewater.In the process of the experiment,the electrode materials,salt-chamber width and cathode types of MDC were preliminarily explored,and the electroproducing microorganisms were identified and analyzed,which will help us to have a deeper understanding of the operation mechanism of MDC and lay a good theoretical foundation for further improving the performance of MDC.