| As a leading manufacturing country in the world,China’s mechanical processing is a crucial part of the national industrial system.For machining,with the extensive use of cutting tools such as cutting dies and lathes in the production process,the demand for cutting fluid is also increasing,resulting in a large amount of cutting waste liquid.At the same time,the cutting waste liquid also has the characteristics of poor degradation performance,complex composition and high COD concentration,which is difficult to deal with.Aiming at the treatment of mechanical processing cutting waste liquid,this paper builds a microbial fuel cell(MFC)experimental bench in the laboratory environment as an electrochemical reaction system;focusing on the development of new electrode materials of biochar modified by polythiophene/multi-walled carbon nanotubes;the MFC device was used to treat mechanical cutting waste liquid,and rhamnolipid was selected as a model biosurfactant to study its enhanced degradation and power generation efficiency.(1)Build a microbial fuel cell device test bench.The microbial fuel cell device adopts a double-chamber structure,and the anode electrogenic bacteria are screened and constructed according to 10 kinds of electrogenic bacteria cultured in the laboratory.Orange peel biochar electrode was prepared.Orange peel was transformed into orange peel biochar material at 400℃,and then PTh/MWCNTs were mixed and modified on the surface of orange peel biochar to prepare a new PTh/MWCNTs orange peel biochar electrode.PTh/MWCNTs were successfully modified on the surface of orange peel biochar anode by FTIR,XRD,SEM and hydrophobicity.Through the COD removal rate and electricity generation test of the MFC device loaded with PTh/MWCNTs modified biochar electrode,the maximum power density can reach 2756 m W/m~2,which is 4.0times and 1.35 times of the traditional carbon cloth electrode and unmodified biochar electrode,respectively.At the same time,the MFC device loaded with the new PTh/MWCNTs orange peel biochar electrode had a COD removal rate of 76%,which was23.4%and 27%higher than that of MFC loaded with unmodified biochar and traditional carbon cloth electrode,respectively.The orange peel biochar electrode modified by PTh/MWCNTs has high porosity and good biocompatibility,which is conducive to microbial attachment and promotes the transfer of electrons between electrodes.It has a great role in promoting the treatment of machining cutting waste liquid and power generation capacity of the MFC device.(2)Rhamnolipid was selected as a model of biosurfactant to study its enhanced MFC degradation and electricity production.By adding rhamnolipid to the anode chamber of the double-chamber MFC,it was found that the power density of the MFC device after adding rhamnolipid was 34.3%higher than that of the MFC device without adding rhamnolipid,the COD removal rate was increased by 80.0%,and the coulombic efficiency was increased by 80.4%.The study of the temperature control module of the MFC device shows that the power density,coulomb efficiency and COD removal rate of the MFC after adding rhamnolipid also increase greatly with the increase of temperature.The results show that increasing the temperature plays a positive role in promoting the rhamnolipid-enhanced MFC device.(3)The simulation model of double-chamber MFC system based on continuous feed state is built.Considering that the MFC experimental process is complex and the cutting waste liquid of the mechanical processing plant is discharged into the sewage treatment tank in a continuous flow state,a two-chamber MFC system simulation model based on continuous feed state is built,and the MFC system is explored from the perspective of model control.Firstly,the reaction mechanism and model conditions of the MFC system are described,and the Simulink simulation model of the dual-chamber MFC system is built according to the charge conservation and mass conservation.The dynamic performance simulation analysis of the built MFC system is carried out to explore the influence of the two key factors of feed flow and current density on the output performance of the MFC system.Finally,the experimental verification and related literature results are analyzed according to the built test bench.The experimental and simulation results show that the model built in this paper is true and reliable,and can clearly express the influence of anode feed flow and feed flow on the output of MFC system from multiple angles.The control and adjustment of cutting waste liquid flow and current density are determined by the capacity of MFC system.(4)The model predictive control method is introduced into the MFC system model.By defining an objective function on the utilization efficiency of cutting waste liquid or material loss,the defined objective function is iteratively calculated by using the idea of cyclic optimization in the model predictive control method to obtain a control sequence.The first component of the control sequence is re-applied to the MFC system,so that the objective function can achieve the minimum value at any time in the prediction time domain.When the objective function value is the smallest,the utilization degree of cutting waste liquid is higher.The simulation results show that the control variables and state variables of the MFC system optimized by the model predictive control method can gradually track to the optimal target point calculated by the controller,which meets the requirements of model predictive control,and the optimized MFC model is more suitable for industrial production. |
PDF Full Text Request