Decomposition of organics in concentrated landfill leachate with ozone/hydrogen peroxide system: Oxidation characteristics and Spectroscopic analyses
CHEN Wei-ming1, ZHANG Ai-ping2, LI Min2, JIANG Guo-bin1, LI Qi-bin1,2
1. Geosciences and Environmental Engineering of Southwest Jiaotong University, Chengdu 611756, P, R. China;
2. Key Laboratory of Special Waste Water Treatment, Sichuan Province Higher Education System, College of Chemistry and Material Science, Sichuan Normal University, Chengdu 610068, China
A concentrated leachate from reverse osmosis (RO)was pre-treated with ozone and hydrogen peroxide. The degradation rate, ORP, alkalinity (as CaCO3) and molecular weight distribution of the organics were investigated, and molecular structure changes of DOM were studied using spectroscopic analyses. Compared to the ozone alone treatment, the ozone/hydrogen peroxide treatment was significantly improved with 4mL/L H2O2 addition. The removal efficiencies of COD, UV254, and CN by 11.01%, 12.92%, and 10.74%, respectively. The degradation rate followed by COD, UV254 and CN, and the chromophore was most easily attacked by ozone. In addition, the biodegradability of the wastewater not only improved effectively but also the ratio of BOD5/COD reached 0.43, and the fractions with large molecular weight such as HA and FA were efficiently decomposed into fractions with small molecular weight. FT-IR analysis indicated DOM of wastewater was oxidized gradually and functional groups like Ar-O disappeared completely. UV-Vis spectra analysis indicated that the humification of the wastewater was greatly deceased by ozone/hydrogen peroxide system, and the degradation of aromatic compounds was also improved significantly with the system. In addition, PARAFAC analysis of excitation emission matrix (EEM) from fluorescence spectroscopy for different samples indicated that C1and C3 were fulvic acid and humic-like substances. C2 was identified as pyrene and its alkylderivates. Ozonation oxidized components C1 and component C3 much faster than component C2.
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