Co-treatment of fruit and vegetable waste in sludge digesters: Chemical and spectroscopic investigation by fluorescence and Fourier transform infrared spectroscopy

Fluorescence intensity of peak B associated with tryptophan-like substances and peak D associated with humic-like substances observed on tridimensional Excitation Emission Matrix maps increased up to sample corresponding to the highest rate of biogas production. Overall spectroscopic results provided evidence of different chemical pathways of anaerobic digestion associated with increasing amount of FVW which led to different levels of biogas production.