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Effect of a trace element addition strategy on volatile fatty acid accumulation in thermophilic anaerobic digestion of food waste

Effect of a trace element addition strategy on volatile fatty acid accumulation in thermophilic anaerobic digestion of food waste
Effect of a trace element addition strategy on volatile fatty acid accumulation in thermophilic anaerobic digestion of food waste
Purpose
A trace element (TE) supplementation strategy previously shown to be effective in mesophilic conditions was tested for thermophilic digestion of source segregated domestic food waste.

Methods
Inoculum from a mesophilic anaerobic digester treating municipal wastewater biosolids was successfully acclimated to thermophilic temperature (55 °C) with food waste as a substrate. Four laboratory-scale digesters were maintained at a loading of 2 g VS l?1 day?1 with one pair receiving TE supplementation. Two more pairs of digesters were incrementally loaded to 3 and 4 g VS l?1 day?1, respectively, and also received TE.

Results
All digesters performed well for the first 3–4 months of operation, but volatile fatty acid (VFA) concentrations in those without TE showed no recovery from an initial small accumulation. On continued operation, VFA concentrations increased in all digesters, especially those at higher loading rates or without TE supplementation, reaching >30 g l?1. Under these meta-stable conditions, a deliberate disturbance to daily feeding (cessation then resumption) led to acetic acid accumulation, a fall in pH and a sharp increase in the ratio of partial to intermediate alkalinity. Increases in VFA corresponded to an increasing total ammonia nitrogen concentration which appeared to become inhibitory at ~2,500 mg N l?1.

Conclusions
While TE supplementation delayed the onset and reduced the rate of VFA accumulation, it was unable to sustain stable digestion of this substrate in thermophilic conditions.
volatile fatty acids, food waste, thermophilic, ammonia, trace elements
1877-2641
Yirong, C.
c8619c16-42e0-4019-9635-1b573c9a4e78
Heaven, S.
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, C.J.
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f
Yirong, C.
c8619c16-42e0-4019-9635-1b573c9a4e78
Heaven, S.
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, C.J.
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f

Yirong, C., Heaven, S. and Banks, C.J. (2014) Effect of a trace element addition strategy on volatile fatty acid accumulation in thermophilic anaerobic digestion of food waste. Waste and Biomass Valorization, 6 ((1), 1-12). (doi:10.1007/s12649-014-9327-2).

Record type: Article

Abstract

Purpose
A trace element (TE) supplementation strategy previously shown to be effective in mesophilic conditions was tested for thermophilic digestion of source segregated domestic food waste.

Methods
Inoculum from a mesophilic anaerobic digester treating municipal wastewater biosolids was successfully acclimated to thermophilic temperature (55 °C) with food waste as a substrate. Four laboratory-scale digesters were maintained at a loading of 2 g VS l?1 day?1 with one pair receiving TE supplementation. Two more pairs of digesters were incrementally loaded to 3 and 4 g VS l?1 day?1, respectively, and also received TE.

Results
All digesters performed well for the first 3–4 months of operation, but volatile fatty acid (VFA) concentrations in those without TE showed no recovery from an initial small accumulation. On continued operation, VFA concentrations increased in all digesters, especially those at higher loading rates or without TE supplementation, reaching >30 g l?1. Under these meta-stable conditions, a deliberate disturbance to daily feeding (cessation then resumption) led to acetic acid accumulation, a fall in pH and a sharp increase in the ratio of partial to intermediate alkalinity. Increases in VFA corresponded to an increasing total ammonia nitrogen concentration which appeared to become inhibitory at ~2,500 mg N l?1.

Conclusions
While TE supplementation delayed the onset and reduced the rate of VFA accumulation, it was unable to sustain stable digestion of this substrate in thermophilic conditions.

Text
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More information

e-pub ahead of print date: November 2014
Keywords: volatile fatty acids, food waste, thermophilic, ammonia, trace elements
Organisations: Water & Environmental Engineering Group

Identifiers

Local EPrints ID: 373233
URI: http://eprints.soton.ac.uk/id/eprint/373233
ISSN: 1877-2641
PURE UUID: f2333a61-c118-42b3-9ccc-3ce909d2e5bd
ORCID for S. Heaven: ORCID iD orcid.org/0000-0001-7798-4683
ORCID for C.J. Banks: ORCID iD orcid.org/0000-0001-6795-814X

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Date deposited: 12 Jan 2015 14:53
Last modified: 15 Mar 2024 02:52

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Contributors

Author: C. Yirong
Author: S. Heaven ORCID iD
Author: C.J. Banks ORCID iD

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