Influence of Hydraulic Retention Time on Characteristics of Dissolved Organic Matter

Abstract:

The influence of hydraulic retention time (thr) on characteristics of dissolved organic matter (DOM) in membrane bioreactor used for restaurant wastewater treatment was studied through gel filtration chromatography (GFC) and excitationemission matrix fluorescence spectra analysis.Results show that the second peaks in GFC spectra of the effluent samples gradually move to the direction of the smaller molecular weight distribution.The molecular weight distribution becomes broader with the decreasing of thr.Meanwhile,molecular weight distribution of extracellular polymeric substances (EPS) in sludges is less affected by thr.The main fluorescent materials in raw water are high and lowexcitation wavelength tryptophan.However,the primary fluorescent substances in effluents are UV and visible fulviclike.With the decrease of thr,highexcitation wavelength tryptophan occurs in effluents of No.4,5 experimental devices.It is also found that the center of this tryptophan peaks are redshifted by 5 nm and 10 nm along the emission axis compared with the influent wastewater,respectively.