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Impact of low loading on digestion of the mechanically-separated organic fraction of municipal solid waste

Impact of low loading on digestion of the mechanically-separated organic fraction of municipal solid waste
Impact of low loading on digestion of the mechanically-separated organic fraction of municipal solid waste
Changing waste management practice, introduction of new technologies, and population demographics and behaviour will impact on both quantity and composition of future waste streams. Laboratory-scale anaerobic digestion of the mechanically-separated organic fraction of municipal solid waste (ms-OFMSW) was carried out at relatively low organic loading rates (OLR), and results analysed using an energy modelling tool. Thermophilic operation with water addition and liquor recycle was compared to co-digestion with dilution water replaced by sewage sludge digestate (SSD); thermophilic and mesophilic mono-digestion were also tested at low OLR. All thermophilic conditions showed stable operation, with specific methane production (SMP) from 0.203-0.296 m3 CH4 kg-1 volatile solids (VS). SSD addition increased biogas production by ~20% and there was evidence of further hydrolysis and degradation of the SSD. Long-term operation at 1 kg VS m-3 day-1 had no adverse effect except in mesophilic conditions where SMP was lower at 0.256 m3 CH4 kg-1 VS and stability was reduced, especially during OLR increases. This was probably due to low total ammonia nitrogen, which stabilised at ~0.2 g N kg-1 and limited the buffering capacity. Energy analysis showed thermophilic operation at OLR 2 g VS L-1 day-1 gave 42% of the theoretical methane potential and 38% of the higher heating value, reducing to 37% and 34% respectively in mesophilic conditions. Scenario modelling indicated that under low ms-OFMSW load even an energy-depleted co-substrate such as SSD could contribute to the energy balance, and would be a better diluent than water due to its nutrient and buffering capacity.
0956-053X
101-112
Zhang, Wei
2ddf6d07-244b-4a0b-8a96-2867deb060d5
Venetsaneas, Nikolaos
12790809-766b-4207-a7fb-356285c3fa33
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, Charles
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f
Zhang, Wei
2ddf6d07-244b-4a0b-8a96-2867deb060d5
Venetsaneas, Nikolaos
12790809-766b-4207-a7fb-356285c3fa33
Heaven, Sonia
f25f74b6-97bd-4a18-b33b-a63084718571
Banks, Charles
5c6c8c4b-5b25-4e37-9058-50fa8d2e926f

Zhang, Wei, Venetsaneas, Nikolaos, Heaven, Sonia and Banks, Charles (2020) Impact of low loading on digestion of the mechanically-separated organic fraction of municipal solid waste. Waste Management, 107, 101-112. (doi:10.1016/j.wasman.2020.03.016).

Record type: Article

Abstract

Changing waste management practice, introduction of new technologies, and population demographics and behaviour will impact on both quantity and composition of future waste streams. Laboratory-scale anaerobic digestion of the mechanically-separated organic fraction of municipal solid waste (ms-OFMSW) was carried out at relatively low organic loading rates (OLR), and results analysed using an energy modelling tool. Thermophilic operation with water addition and liquor recycle was compared to co-digestion with dilution water replaced by sewage sludge digestate (SSD); thermophilic and mesophilic mono-digestion were also tested at low OLR. All thermophilic conditions showed stable operation, with specific methane production (SMP) from 0.203-0.296 m3 CH4 kg-1 volatile solids (VS). SSD addition increased biogas production by ~20% and there was evidence of further hydrolysis and degradation of the SSD. Long-term operation at 1 kg VS m-3 day-1 had no adverse effect except in mesophilic conditions where SMP was lower at 0.256 m3 CH4 kg-1 VS and stability was reduced, especially during OLR increases. This was probably due to low total ammonia nitrogen, which stabilised at ~0.2 g N kg-1 and limited the buffering capacity. Energy analysis showed thermophilic operation at OLR 2 g VS L-1 day-1 gave 42% of the theoretical methane potential and 38% of the higher heating value, reducing to 37% and 34% respectively in mesophilic conditions. Scenario modelling indicated that under low ms-OFMSW load even an energy-depleted co-substrate such as SSD could contribute to the energy balance, and would be a better diluent than water due to its nutrient and buffering capacity.

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Accepted/In Press date: 12 March 2020
e-pub ahead of print date: 22 April 2020

Identifiers

Local EPrints ID: 439004
URI: http://eprints.soton.ac.uk/id/eprint/439004
ISSN: 0956-053X
PURE UUID: 00eb4000-8a1c-4888-b6fc-21d231129994
ORCID for Nikolaos Venetsaneas: ORCID iD orcid.org/0000-0003-2985-3261
ORCID for Sonia Heaven: ORCID iD orcid.org/0000-0001-7798-4683

Catalogue record

Date deposited: 31 Mar 2020 16:31
Last modified: 07 Oct 2020 01:37

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