Municipal Solid Waste Stabilization Efficiency Using Fluorescence Excitation–Emission Spectroscopy

The use of fluorescence excitation-emission spectroscopy as a complementary tool to evaluate the biological stability of municipal solid waste during anaerobic degradation is investigated in this paper, and whether correlations between the stability of MSW and fluorescence spectroscopic analysis of leachate can be established. In this study, EEM spectra indicated the presence of three different fluorophores centred, 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 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 nm, 360/390 nm, 360/470 nm, 390/430 nm) and standard degradation parameters (i.e., methane, carbon dioxide, total organic carbon, total inorganic carbon and pH). Strong correlations were obtained between the cumulated volume of methane produced during the biodegradation process and peaks at Ex/Em wavelength pairs 280/360 nm and 360/390 nm, which were identified as indicators for biological stability. The 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 municipal solid waste stabilization during anaerobic degradation.