Municipal Solid Waste Stabilization Efficiency Using Fluorescence Excitation–Emission Spectroscopy

Abstract

Use of fluorescence excitation–emission spectroscopy as a complementary tool to evaluate the biological stability of municipal solid waste (MSW) during anaerobic degradation was investigated, and whether correlation between the stability of MSW and fluorescence spectroscopic analysis of leachate can be established. In this study, excitation–emission matrix (EEM) spectra indicated the presence of three different fluorophores, centered at Ex/Em wavelength pairs of α: 250–280/315–350 nm; β: 340–350/400–450 nm; and δ: 420–450/470–530 nm; these fluorophores are attributed, respectively, to protein-like, fulvic-like, and humic-like structures. An exhaustive inventory of all fluorescence emission peaks in EEM and in synchronous spectra obtained at different Δλ and different degradation times was compiled. Correlations were sought between emission peaks (i.e., 280/360, 360/390, 360/470, and 390/430 nm) and standard degradation parameters (i.e., methane [CH4], CO2, total organic carbon, total inorganic carbon, and pH). Strong correlations were obtained between the cumulative volume of CH4 produced during the biodegradation process and peaks at Ex/Em wavelength pairs 280/360 and 360/390 nm, which were identified as indicators for biological stability. Results of this study encourage the use of fluorescence spectroscopy measurements of leachate as a relatively rapid and valuable tool for the industry and research to assess the degree of MSW stabilization during anaerobic degradation.