Study On Excess Sludge Reduction And Hydrogen Production In Microbial Electrochemical System Combined With Photocatalysis

With the pressure of treatment and disposal of waste sludge in the sewage treatment plant of our country and energy crisis,microbial electrochemical system,a newly developed excess sludge reduction and hydrogen production technology,provides a new way for reducing the pressure of residual sludge treatment and disposal and energy problem.At present,the high cost of cathodic platinum?Pt?catalysts,which is commonly used in research,limits itspractical applications.In this study,the effects and feasibility of using cheap cuprous oxide photocatalyst as a substitute for Pt was studied.The MEC experiments with different applied voltage and load of different catalysts were carried out respectively using a single chamber microbial electrolysis cell?MEC?.The current density curve,hydrogen production performance and sludge reduction were compared to characterize the performance of MEC on sludge reduction and hydrogen production.The main experimental contents and results are as follows:In the single chamber MEC experiment without illumination,when the applied voltage increased from 1V to 1.2V,the maximum current density increased from 61.4A/m³ to 66.3A/m³,the rate of hydrogen production increased by 16%,and the removal rate of VSS and SCOD increased by 4%and 16%,respectively.When the load of Pt/C catalyst increased from0.5mg/cm² to 0.75 mg/cm²,the maximum current density 66.3A/m³ increased to 90.3A/m³,the hydrogen production rate increased by 22%,the hydrogen yield increased by 29%,and the VSS and SCOD removal rates increased by 4%and 4%,respectively.In the Cu₂O photocatalytic MEC experiment under ultraviolet light,when the applied voltage increased from 1V to 1.2V,the maximum current density increased from 53.5A/m³ to60.3A/m³,the hydrogen production rate increased by 24%,and the removal rate of VSS and SCOD increased by 3%and 8%,respectively.When the catalyst load increased from 0.5mg/cm²to 0.75 mg/cm²,the maximum current density 60.3A/m³ increased to 70.0A/m³,the hydrogen production rate increased by 15%,and the removal rate of VSS and SCOD increased by 4%and 3%,respectively.However,the long-term stability of Cu₂O photocatalyst needs to be improved.Comparing the sludge reduction and hydrogen production performance of Cu₂O photocatalytic MEC and Pt/C cathode MEC,it is found that thecurrent density,hydrogen production performance and sludge reduction in Cu₂O photocatalytic MEC were similar to those in platinum carbon cathode MEC.This shows that Cu₂O photocatalyst is a promising cathode catalyst,which is expected to be a cheap substitute for the precious metal Pt catalyst.