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Post-treatment of dewatered digested sewage sludge by thermophilic high-solid digestion for pasteurization with positive energy output

Nordell, E. and Moestedt, J. and Yekta, S. Shakeri and Bjorn, A. and Sun, Li and Schnürer, Anna (2021). Post-treatment of dewatered digested sewage sludge by thermophilic high-solid digestion for pasteurization with positive energy output. Waste Management. 119 , 11-21
[Research article]

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Abstract

This study investigated the possibility to use thermophilic anaerobic high solid digestion of dewatered digested sewage sludge (DDS) at a wastewater treatment plant (WWTP) as a measure to increase total methane yield, achieve pasteurization and reduce risk for methane emissions during storage of the digestate. A pilot-scale plug-flow reactor was used to mimic thermophilic post-treatment of DDS from a WWTP in Linkoping, Sweden. Process operation was evaluated with respect to biogas process performance, using both chemical and microbiological parameters. Initially, the process showed disturbance, with low methane yields and high volatile fatty acid (VFA) accumulation. However, after initiation of digestate recirculation performance improved and the specific methane production reached 46 mL CH4/g VS. Plug flow conditions were assessed with lithium chloride and the hydraulic retention time (HRT) was determined to be 19-29 days, sufficient to reach successful pasteurization. Degradation rate of raw protein was high and resulted in ammonia-nitrogen levels of up to 2.0 g/L and a 30% lower protein content in the digestate as compared to DDS. Microbial analysis suggested a shift in the methane producing pathway, with dominance of syntrophic acetate oxidation and the candidate methanogen family WSA2 by the end of the experiment. Energy balance calculations based on annual DDS production of 10 000 ton/year showed that introduction of high-solid digestion as a post-treatment and pasteurization method would result in a positive energy output of 340 MWh/year. Post-digestion of DDS also decreased residual methane potential (RMP) by >96% compared with fresh DDS. (C) 2020 The Authors. Published by Elsevier Ltd.

Authors/Creators:Nordell, E. and Moestedt, J. and Yekta, S. Shakeri and Bjorn, A. and Sun, Li and Schnürer, Anna
Title:Post-treatment of dewatered digested sewage sludge by thermophilic high-solid digestion for pasteurization with positive energy output
Series Name/Journal:Waste Management
Year of publishing :2021
Volume:119
Page range:11-21
Number of Pages:11
Publisher:PERGAMON-ELSEVIER SCIENCE LTD
ISSN:0956-053X
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 209 Industrial Biotechnology > Bioenergy
Keywords:Digestate post treatment, Dry digestion, Ammonia, Microbial community structure, Residual methane potential
URN:NBN:urn:nbn:se:slu:epsilon-p-110051
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-110051
Additional ID:
Type of IDID
DOI10.1016/j.wasman.2020.09.028
Web of Science (WoS)000599766200002
ID Code:21429
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Molecular Sciences
Deposited By: SLUpub Connector
Deposited On:21 Jan 2021 10:23
Metadata Last Modified:21 Jan 2021 10:31

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