Denitrification And Electricity Generation In Photocatalytic Synergistic Microbial Fuel Cells

To deal with the problem of low carbon nitrogen wastewater treatment in Chinese sewage treatment plant,three kinds of microbial fuel cells were constructed in three steps,which have production capacity of Anode denitrification MFC?Double chamber simultaneous denitrification MFC and Photocatalytic synergistic MFC.The microbial fuel cell system is coupled to the photocatalytic technology finally.This system can combine both of the excellent properties of the microbial fuel cell and the high efficiency of the photocatalytic technology.In this paper,effects of organic matter and ammonia on denitrification efficiency and power generation capacity of three kinds of microbial fuel cells were studied.The influence of light intensity on Photocatalytic synergistic MFC was also studied.We compared the effects of photocatalytic units on the denitrification and power generation of MFC.The feasibility of ammonia nitrogen as an electron donor in microbial fuel cell were alsostudied.The system has been a stable denitrification effect.It is argued that low-carbon ammonia nitrogen wastewater can be treated in microbial fuel cell.The paper has the following main conclusions:(1)In anode denitrification MFCs,the concentration of organic matter is one of the important factors that affect the denitrification of ystem.The production cycle decreases with the decrease of the concentration of organic matter.When the influent organic concentration decreased from 600 mg / L to 0mg / L,the production cycle decreased from 7401 min to 1350 min.With the decrease of COD,the removal rate of ammonia nitrogen was improved,when the organic matter in the influent was 100 mg / L,the removal rate of ammonia nitrogen was the largest,at 50.18%,and the removal was 33.54 mg/L,but the removal rate of ammonia nitrogen decreased slightly when COD concentration was further decreased.(2)In anode denitrification MFCs,ammonia nitrogen concentration comprehensively affects the system power generation and denitrification capacity.Research shows that under the experimental conditions of ammonia nitrogen concentration was 180mg/L and low carbon sources,the system has a good denitrogen production capacity,the output voltage is up to 670 mv,ammonia removal rate is up to 70%.Ammonia nitrogen concentration is the main factor affecting the system denitrification,low concentration and high concentration of ammonia nitrogen are not conducive to system denitrification.At the same time,high concentration of ammonia will affect the system's power generation performance.Under the condition of 50 mg / LCOD and 0mg / LCOD,the system of high concentration of ammonia nitrogen was lower than that of low concentration ammonia nitrogen,indicating that high concentrations of ammonia nitrogen have an inhibitory effect on microorganisms.(3)In double chamber simultaneous denitrification MFCs,the concentration of organic matter is one of the important factors affecting the denitrification of the system.The production cycle decreases with the decrease of the concentration of organic matter.When the influent organic concentration decreased from 300 mg / L to 0mg / L,the production cycle decreased from 5024 min to 716 min.Under the experimental conditions,the system maintained good nitrate nitrogen removal ability.The removal rate of ammonia nitrogen was systematically studied.The maximum removal rate of ammonia nitrogen was 13.78 mg / L,and the removal rate of 10.91% could be maintained without influencing organic matter?(4)In double chamber simultaneous denitrification MFCs,the concentration of ammonia in the anode chamber is one of the important factors affecting the denitrification of the system.With the increase of ammonia concentration,ammonia nitrogen removal rate and stable output voltage first increased and then decreased.The removal rate has reached the maximum removal rate and removal rate when the concentration of ammonia nitrogen was 180 mg / L,which was 48.6%,87.5mg / L.At a concentration of 240 m g/L of ammonia,the system achieves the highest stable output voltage of 328 mV(R=500?).High concentrations of ammonia will inhibit the growth of microorganisms.(5)In photocatalytic synergistic MFC,the addition of photocatalytic units has weak effect on the system's electrodynamic cycle,and the production cycle has different reduction.The maximum reduction was 306 min when the influent COD concentration was 100mg/L.With the addition of photocatalytic units,the removal rate of ammonia nitrogen and nitrate nitrogen under different influent organic concentrations were improved.Under low concentrations of influent organic matter(0 and 50 mg / L),the removal rate of ammonia nitrogen and nitrate nitrogen was most.When the influent organic matter concentration is 50 mg / L,the removal rate of ammonia nitrogen is increased by 14.21%.In the absence of organic matter,the removal rate of nitrate nitrogen was the highest,which was 4.67%?(6)In Photocatalytic synergistic MFC,the light intensity has a weak effect on the system power generation and denitrification.As the intensity of the light increased,the output voltage increased,and the removal effect of ammonia nitrogen and the removal effect of nitrate nitrogen were also increased.The change rule of nitrate nitrogen and ammonia nitrogen removal rate is similar to stable output voltage.(7)The microbes of the three MFC systems were able to survive well and the diversity of biological samples was good.The anodized ammonia-oxidized MFCs anode has the best biodiversity,however the anode biodiversity is the worst in Double chamber simultaneous denitrification MFCs.After the photocatalytic unit was added,the microbial abundance of the dual-room microbial fuel cells increased,and the microorganism grows better.It is proved that there is synergistic effect between photocatalytic unit and MFC.