Anaerobic co-digestion of food waste/excess sludge: substrates - products transformation and role of NADH as an indicator
Journal
Journal of Environmental Management
Journal Volume
232
Pages
197-206
Date Issued
2019
Author(s)
Abstract
The process of anaerobic co-digestion is vital importance to resource recovery from organic solid wastes such as food waste and municipal sludge. However, its application is hindered by the limited understanding on the complex substrates-products transformation reactions and mechanisms therein. In this study, food waste (FW) and excess sludge (ES) from municipal wastewater treatment were mixed at various ratios (ES/FW 5:0, 4:1, 2:1, 1:1, 1:2, 1:4, w/w), and the co-digestion process was studied in a batch test. The consumption of substrates including soluble proteins and carbohydrates, the variation in the intermediates such as various volatile fatty acids, and the production of hydrogen and methane gases were monitored. The results suggested that 4:1 was likely the optimal ratio where substrates were consumed and biogas generated efficiently, whereas 1:2 and 1:4 caused severe inhibition. Fermentation of ES alone produced mainly acetic and propionic acid, while the addition of FW led to butyric acid type fermentation. Intermediates in the fermentation liquid were tentatively identified, and the levels of NADH quantified using 3D-excitation/emission fluorescence spectrometry. One class of the intermediates, tryptophan-like proteins were correlated to the butyric acid accumulation in ES/FW mixtures, and NADH level was proposed as an indicator of VFAs production activities. © 2018 Elsevier Ltd
Subjects
Anaerobic co-digestion (coAD); Excess sludge/food waste (ES/FW); Nicotinamide adenine dinucleotide (NADH); Substrates - products transformation; Volatile fatty acids (VFAs)
Other Subjects
acetic acid; biogas; butyric acid; carbohydrate; humic acid; hydrogen; isobutyric acid; isovaleric acid; methane; propionic acid; protein; reduced nicotinamide adenine dinucleotide; valeric acid; volatile fatty acid; nicotinamide adenine dinucleotide; anaerobic digestion; fatty acid; fermentation; food waste; organic acid; sludge; substrate; transformation; wastewater treatment; anaerobic digestion; anaerobic fermentation; Article; bioaccumulation; biofuel production; excess sludge; food waste; industrial production; nonhuman; quantitative analysis; sludge; spectrofluorometry; waste water management; anaerobic growth; bioreactor; food; sewage; Anaerobiosis; Bioreactors; Fatty Acids, Volatile; Food; Methane; NAD; Sewage
Type
journal article