Application Research Of Dual Sensor System In UASB-MFC Coupling System

In recent years,up-flow anaerobic sludge bed reactor(UASB)as an efficient anaerobic biological treatment technology has been widely concerned by sewage treatment researchers.However,the stability of the UASB reactor is poor in the long-term operation process,and cause an amount accumulation of volatile fatty acids in the system.Therefore,some ancillary equipment are often needed to monitor the operation of UASB reactor.However,the auxiliary equipment can’t meet the requirement of on-line monitoring.Moreover,the consumption of electric energy increases the running cost.The above problems has been inhibited the development of UASB reactor.Microbial fuel cell(MFC)as an energy self-sustaining and cleaning sewage treatment technology,which can convert biomass to electrical signals by exoelectrogenes decompose the organic matter and releases electrons to the cells.On the basis of this,the novel of UASB-MFC dual sensors system was constructed,which the single chamber non-membrane air cathode MFCs were coupled with a UASB reactor.In order to improve the stability of anaerobic reaction and the treatment efficiency of UASB reactor,MFC is used as the biosensor for the coupling system to monitor the running state of UASB reactor by electric signal.Meanwhile,owing to the internal synergy effect of the dual sensors system,the high potential(HPOT)method is used to accelerate the voltage recovery,and the degradation of electrode is cleaned by the in-suit ECS connection method to improve the performance of the MFC,and the results show that:(1)MFCsludge layer is more suitable for the monitor of total volatile fatty acid(TVFA),MFCsuspended layer is more suitable for chemical oxygen demand(COD)monitoring.Electrochemical analysis demonstrated that lower proton transfer resistance determine the higher sensitivity of MFCsuspended layer,and the difference in species resulted in stronger inhibition of volatile fatty acids on MFC in the sludge layer.(2)The potential allocation between MFCs can accelerate the voltage recovery of the biosensor after being restrained by unfavorable environment,and shorten the recovery time to 55%of the natural-state recovery time.(3)After more than one year steady operation,it is found that the voltage of MFC decreased,among which the degradation of cathode performance is the main reason cause the decline of MFC performance.The degradation of cathode performance is mainly due to the adhesion of biofilm on the cathode surface and the precipitation of calcium and magnesium ions.(4)The performance of MFC can be recovered by in-situ ECS cleaning and AC field cleaning,and the maximum power density can be restored to 83.2%-84.6%of the original state.