Structural transformation of dissolved organic matters in leachate after advanced Fenton treatment

In order to increase the organic matter removal rate during advanced treatment, the characteristics and transformation of dissolved organic matter(DOM) in SBR effluent during the Fenton oxidation in laboratory scale were studied. DOM was fractionated using XAD resins into 5 fractions: hydrophobic acid(HPO-A), hydrophobic neutral(HPO-N), transphilic acid(TPI-A), transphilic neutral(TPI-N) and hydrophilic fraction(HPI). The HPO-A and HPO-N occupy 67% of the DOM. Dissolved organic carbon(DOC) was removed by 60.01% and the significant changes in fluorescence properties of DOM were observed during Fenton oxidation. The SUVA of all the five fractions increased, which showed the enrichment of aromatic structures. The DOM fractions also exhibited different changes in Fourier-transform infrared(FT-IR) spectra characteristics during Fenton oxidation. It indicated that carboxylic acids existed as a major functional group in the SBR effluent HPO-A and TPI-A. HPO-N and TPI-N were similar, with greater hydrocarbon character and less carboxylic acid character than other fractions. Fenton oxidation resulted in the enrichment of C-O, CO and aromatic structures and the decreased content of O-H and -COOH functional groups in DOM. On the other hand, the production of amide-1 functional groups occurred.