Spectra Analysis of Dissolved Organic Matter in Pretreatment Process of Leachate Treated by Reverse Osmosis

In order to examine the removal of organic matter in the leachate which results in reverse osmosis (RO) membrane fouling, and to provides a reference to select appropriate pretreatment processes of RO, synchronous-scan fluorescence, three-dimensional excitation emission matrix fluorescence spectroscopic and UV-Vis spectrum of the dissolved organic matter (DOM) in different molecular weight range in effluent from each leachate process of "biochemical (UASB+A/O) and UF" pretreatment in some incineration plant were examined. The results of synchronous fluorescence spectra analysis showed that DOM in the wavelength range of 250 similar to 320 run with all the molecular weight and in the wavelength>320 nm with molecular weight>1 KDa was removed obviously by the pretreatment processes. The results of three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectra showed that the pretreatment processes removed low-excitation wavelength tyrosine-like, low-excitation wavelength tryptophan-like and high-excitation wavelength tryptophan-like with all the molecular weight off, and fulvic-like matter and high-excitation wave length tyrosine-like with molecular weight>1 KDa effectively. The results of UV-Vis spectra analysis showed that the pretreatment processes removed DOM of molecular weight>1 KDa with pi-pi* transition and DOM of all molecular weight with conjugated system of the benzene ring structure. It was concluded that the removal of both fulvic-like matter and high-excitation wave length tyrosine-like with the wavelength>320 nm, molecular weight<1 KDa and with pi-pi* transition should be strengthened for controlling (RO) membrane fouling, when leachate was treated by RO with the pretreatment processes of "biochemical(UASB+A/O)and UF".