Co-treatment of fruit and vegetable waste in sludge digesters: Chemical and spectroscopic investigation by fluorescence and Fourier transform infrared spectroscopy. (April 2016)

• Record Type: Journal Article
• Authors: Provenzano, Maria Rosaria; Cavallo, Ornella; Malerba, Anna Daniela; Di Maria, Francesco; Cucina, Mirko; Massaccesi, Luisa; Gigliotti, Giovanni
• Is Part Of: Waste management. Volume 50(2016)
• Page Start: 283
• Page End: 289
• Publication Date: 2016-04
• Subjects: Anaerobic digestion -- Sewage sludge -- Fruit and vegetable waste -- Humification parameters -- Spectroscopic analysis; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2016.02.026
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: The amount of sludge produced annually all over the world is steadily increasing. Humification parameters were evaluated on digestates from food waste and sewage sludge. Fluorescence and FTIR spectra were applied to characterize these digestates. Humification parameters were related to the different chemical composition of substrates. FTIR spectra provided results associated with biogas production. Fluorescence intensity of EEM spectra matched the biogas production trend. Abstract: In a previous work co-digestion of food waste and sewage sludge was performed in a pilot apparatus reproducing operating conditions of an existing full scale digester and processing waste mixed sludge (WMS) and fruit and vegetable waste (FVW) at different organic loading rates. An analysis of the relationship among bio-methane generation, process stability and digestate phytotoxicity was conducted. In this paper we considered humification parameters and spectroscopic analysis. Humification parameters indicated a higher not humified fraction (NH) and a lower degree of humification (DH) of FVW with respect to WMS (NH = 19.22 and 5.10%; DH = 36.65 and 61.94% for FVW and WMS, respectively) associated with their different chemical compositions and with the stabilization process previously undergone by sludge. FVW additions seemed to be favourable from an agronomical point of view since a lower percentage of organic carbon was lost. Fourier transform infrared spectra suggested consumption of aliphatics associated with rising in bio-methane generation followed by accumulation of aliphatics and carboxylic acids when the biogas production dropped. The trend of peaks ratios can be used as an indicator of the process efficiency. 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.