Construction Of Different Electrochemical Systems And Treatment Of Their Coking Wastewater

There are many kinds of harmful substances in coking wastewater,and its non-compliance discharge has a huge impact on the environment.At present,most of the in-depth treatment methods have some disadvantages in the use process,so it is extremely urgent to look for effective in-depth treatment processes and study their mechanisms.The electrochemical system(BES)is a promising advanced processing technology that includes microbial fuel cells(MFCs)and micro-electrolytic cells(MECs).This paper constructed three different electrochemical devices,including proton exchange membrane microbial fuel cells(PEMFC),two-chamber membraneless microbial fuel cells,and iron-carbon microelectrolysis cells.The power generation performances of the two fuel cells were studied separately,the microbial community structure of the microbial cell membrane was investigated,and the treatment capacity of the coking wastewater in the fuel cell and the micro-electrolysis cell was studied.The results showed that:(1)MFC reactor can produce a stable voltage output.In the membraneless MFC reactor,as the coking wastewater treatment load in the reactor increases,the maximum voltage of the MFC decreases,the power density first increases and then decreases,and the internal resistance decreases.When the influent CODcr content was 1g/L·d,the maximum voltage of the battery reached 0.56 V,and the maximum power density reached 1.22 W m-3.In the final influent CODcr content of 6g/L·d,the battery voltage dropped to 0.43V;the battery power density dropped to 0.89 W m-3.When the PEMFC reactor has a higher power generation capability and the current density is 240.8Am-3,the maximum power density reaches 105.2±12.6 W m-3,which is close to the highest power output level in the biocathode MFC(83–117 W m-3).(2)The bacteria on the biocathode can promote the cathodic reduction reaction of microbial fuel cells.In this study,the pyrophosphate sequencing method was used to describe the cathode bacterial community with high reducing activity and it was found to be highly diverse.Community structure analysis showed that the community structure on the cathode biofilm was dominated by the following bacteria: Proteobacteria(42.7%),Firmicutes(25.0%),9.7% Bacteroidetes(9.7%),Actinobacteria(7.7%)and Aquificae(7.1%).Functional component analysis showed that membrane transport is the most important metabolic activity in this community(3)The double-compartment microbial fuel cell has good removal of pollutants from coking wastewater.When the coking wastewater treatment load is CODcr 1,2,3,4g/L·d,the removal rate of NH4+-N reaches more than 99%,and CODcr is the largest.Removal rate reached more than 90%.After the increase of daily influent CODcr content,the removal rate of pollutants will have a downward trend,the CODcr removal rate was reduced by 16.09%.The iron and carbon electrode micro-electrolysis method was used to treat the biochemical water of coking wastewater.The results show that the COD and chroma in the coking wastewater have better treatment effects by deeply treating the coking wastewater with the iron-carbon micro-electrolysis process.120 h final effluent CODcr removal rate reached 72.4±4.4%.In the treatment of coking wastewater by micro-electrolysis,as the reaction time increases,the type and content of organic matter in the treated water sample decrease significantly.The iron-carbon electrode can effectively reduce the concentration of organic matter and remove most of the benzene ring material.Through the research of this subject,the influencing factors of electrochemical system performance were further clarified,the characteristics of microbial communities were revealed,the mechanism of pollutant removal in coking wastewater was clarified,and a certain basis was provided for the advanced treatment of coking wastewater.