Integrity Detection Of Membrane Components Of Membrane Bioreactor Based On Spectral Response

Hollow fiber membranes are also widely used in water treatment processes because of their advantages in terms of specific surface area and membrane flux.However,in practical applications,once the integrity of the membrane module is destroyed,macromolecular organics,colloids,bacteria,viruses and other microorganisms in the raw water will enter the permeate side through the damaged location,affecting the quality of the effluent water.And in the current detection methods,there are problems such as inability to perform online detection,complicated operation,and high cost.Therefore,how to effectively detect membrane breakage is particularly important for drinking water safety and sewage discharge.In this paper,the detection methods of MBR membrane module integrity based on fluorescence spectrum and ultraviolet-visible absorption spectrum are studied.The MBR supernatant was classified through filter membranes with different molecular weight cut-offs to determine the molecular weight distribution of organics.Fluorescence emission spectrum,fluorescence area integration?FRI?technology and ultraviolet log spectrum,study the detection under different working conditions such as sludge concentration,membrane module damage rate,and membrane module damage time.The results are compared with the results of particle counters to verify their feasibility in practice.In order to realize the technology for membrane integrity monitoring,a portable fluorescence detector based on spectral detection was established.The results show that:According to the PARAFAC model combined with FRI,the fluorescence spectrum can be divided into four regions,which are two protein-like species,one humic-like species and one fulvic-like species.Protein-like species mainly exist in the form of macromolecules with a molecular weight greater than 10 k Da.The molecular weight of fulvic-like species and humic-like species is generally greater than 1 k Da and less than 10 k Da.The sludge concentration mainly affects the dissolved organic matter?DOM?in the range of 1k Da-0.45?m,which covers all four of the above species,and fluorescence characteristics are more susceptible to protein-like species.With the increase of the number of broken fibers,DOM will leak into the permeate,which will increase the FRI value of fluorescence detection,increase the fluorescence peak value,and gradually increase the absorbance of UV log spectrum.For different membrane filament breakage rates,tryptophan substances and aromatic proteins have better correlations than fulvic-like species and humic-like species.Correlation coefficients between the fluorescence region integral?FRI?results and different breakage rates were 0.98 and 0.987,respectively.The fluorescence interception change index?f_i?and the slope of the ultraviolet log spectrum(Slope_280-350)also have a good correlation with the breakage rate of the permeate.The leakage of organic matter can be detected when the membrane module is breakage for 30 s.The fluorescence interception change index?f_i?,FRI value?i,n,and ultraviolet log spectrum absorbance can effectively reflect the integrity of the membrane module.Protein-like species could be used as a good indicator of rapid response to MBR membrane integrity testing.Compared with particle count detection,fluorescence spectrum and ultraviolet spectrum detection have good practicability in response time and feedback accuracy,and do not need to add a tracer.The sensitivity LRV value of the FRI detection can reach 4.26.Besides,it provides a method for MBR's real-time membrane filtration detection and water quality analysis.