Improvement of anaerobic digestion of sewage mixed sludge using free nitrous acid and Fenton pre-treatment

Hallaji, S, Torabian, A, Aminzadeh, B, Zahedi, S and Eshtiaghi, N 2018, 'Improvement of anaerobic digestion of sewage mixed sludge using free nitrous acid and Fenton pre-treatment', Biotechnology for Biofuels, vol. 11, no. 1, pp. 1-12.

Document type: Journal Article
Collection: Journal Articles

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Title Improvement of anaerobic digestion of sewage mixed sludge using free nitrous acid and Fenton pre-treatment
Author(s) Hallaji, S
Torabian, A
Aminzadeh, B
Zahedi, S
Eshtiaghi, N
Year 2018
Journal name Biotechnology for Biofuels
Volume number 11
Issue number 1
Start page 1
End page 12
Total pages 12
Publisher BioMed Central
Abstract Background: Recently, it has been indicated that free nitrous acid (FNA) and Fenton pre-treatment of waste activated sludge can enhance methane production in anaerobic digestion of waste activated sludge. In addition, it has been revealed that the substances used in these pre-treatments are both eco-friendly and economically attractive because not only are they produced in anaerobic digestion, but they are also low priced. Since primary sludge and waste activated sludge are mixed prior to anaerobic digestion in the majority of wastewater treatment plants, this study aims to assess the influence of combined FNA and Fenton on the anaerobic digestion of mixed sludge. Results: According to this study's results, methane generation from anaerobic digestion of mixed sludge was enhanced when using FNA and Fenton pre-treatment, affirming the effectiveness of the individual and combined pre-treatments in anaerobic digestion of mixed sludge. The enhanced methane production was significant in combined pre-treatments (up to 72%), compared with FNA and Fenton pre-treatment alone (25% and 27%, respectively). This corroborates the positive synergistic effect of the combined pre-treatments on methane production. The enhanced methane can be attributed to augmented soluble fractions of organic matter in addition to increased readily biodegradable organic matter, caused by the pre-treatments. Additionally, the amount of chemical oxygen demand (COD) was assessed during anaerobic digestion, and it was revealed that COD decreased considerably when the pre-treatment strategies were combined. Conclusions: This study reveals that the pre-treatments are potentially applicable to full-scale wastewater treatment plants because a mixture of primary sludge and waste activated sludge was used for the pre-treatments. Additionally, combined FNA and Fenton pre-treatments prove more effective in enhancing methane production and organic removal than these pre-treatments alone. The enhanced methane prod
Subject Wastewater Treatment Processes
Keyword(s) Anaerobic digestion
Fenton reagent
Free nitrous acid
Methane production
Sewage sludge
DOI - identifier 10.1186/s13068-018-1235-4
Copyright notice © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (
ISSN 1754-6834
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