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Waste Manag. 2018 Mar;73:156-164. doi: 10.1016/j.wasman.2017.12.027. Epub 2018 Jan 4.

Influence of feed/inoculum ratios and waste cooking oil content on the mesophilic anaerobic digestion of food waste.

Author information

1
School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory for Solid Waste Management and Environment Safety (Tsinghua University), Ministry of Education of China, Tsinghua University, Beijing 100084, China.
2
School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory for Solid Waste Management and Environment Safety (Tsinghua University), Ministry of Education of China, Tsinghua University, Beijing 100084, China. Electronic address: jinyy@tsinghua.edu.cn.
3
Dept of Civil, Environ & Geomatic Eng, University College London, London WC1E 6BT, UK.

Abstract

Information on the anaerobic digestion (AD) of food waste (FW) with different waste cooking oil contents is limited in terms of the effect of the initial substrate concentrations. In this work, batch tests were performed to evaluate the combined effects of waste cooking oil content (33-53%) and feed/inoculum (F/I) ratios (0.5-1.2) on biogas/methane yield, process stability parameters and organics reduction during the FW AD. Both waste cooking oil and the inoculation ratios were found to affect digestion parameters during the AD process start-up and the F/I ratio was the predominant factor affecting AD after the start-up phase. The possible inhibition due to acidification caused by volatile fatty acids accumulation, low pH values and long-chain fatty acids was reversible. The characteristics of the final digestate indicated a stable anaerobic system, whereas samples with F/I ratios ranging from 0.8 to 1.2 display higher propionic and valeric acid contents and high amounts of total ammonia nitrogen and free ammonia nitrogen. Overall, F/I ratios higher than 0.70 caused inhibition and resulted in low biogas/methane yields from the FW.

KEYWORDS:

Anaerobic digestion of food waste; Biogas; Digestate; Feed/inoculum ratios; Waste cooking oil

PMID:
29307470
DOI:
10.1016/j.wasman.2017.12.027
[Indexed for MEDLINE]

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