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18 February 2021 Effect of Stillage Pretreatment During a Coupled Scoria-Supported Anaerobic Digestion Followed by Aerobic Degradation
Getachew Dagnew Gebreeyessus, Andualem Mekonnen, Yonas Chebude, Perumal Asaithambi, Trichur Ramaswamy Sreekrishnan, Esayas Alemayehu
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Abstract

The objective of this study was to evaluate the treatment efficiency of a coupled stillage anaerobic digestion, which was performed in scoria-packed continuous reactors and following aerobic degradation. The optimum organic loading rate was determined for the continuous anaerobic digestion of a molasses ethanol distillery stillage with and without wet air feed pretreatment. The pretreatment of the molasses ethanol distillery stillage brought a significantly higher chemical oxygen demand removal in anaerobic digestion with an increased loading rate of 2000 mg/L d when compared with the raw stillage. The results also showed a complete removal of the biological oxygen demand following the coupling of anaerobic digestion with aerobic degradation. During the later stillage aerobic treatment, 68% of the chemical oxygen demand was removed within 8 hours of retention time. Despite the color, the removal of organics in stillage due to integrating wet air pretreatment, continuous anaerobic digestion, and aerobic degradation was successful. The pretreatment and hybrid technique also appears as a promising technique toward the sustainable management of stillage, thereby meeting discharge limit set for the ethanol industry by regulators.

© The Author(s) 2021 This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Getachew Dagnew Gebreeyessus, Andualem Mekonnen, Yonas Chebude, Perumal Asaithambi, Trichur Ramaswamy Sreekrishnan, and Esayas Alemayehu "Effect of Stillage Pretreatment During a Coupled Scoria-Supported Anaerobic Digestion Followed by Aerobic Degradation," Air, Soil and Water Research 14(1), (18 February 2021). https://doi.org/10.1177/1178622121991810
Received: 30 September 2020; Accepted: 11 January 2021; Published: 18 February 2021
KEYWORDS
chemical oxygen demand
organic loading rate
pretreatment
scoria
stillage
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