Title: Acidogenic fermentation of cassava wastewater for volatile fatty acids production

Authors: Mirian Yasmine Krauspenhar Niz; Edinéia Lazarotto Formagini; Marc Àrpad Boncz; Paula Loureiro Paulo

Addresses: Faculty of Engineering, Architecture and Urbanism and Geography, Federal University of Mato Grosso do Sul, Avenida Costa e Silva S/N, Cidade Universitária, Campo Grande-MS, Brazil ' Faculty of Engineering, Architecture and Urbanism and Geography, Federal University of Mato Grosso do Sul, Avenida Costa e Silva S/N, Cidade Universitária, Campo Grande-MS, Brazil ' Faculty of Engineering, Architecture and Urbanism and Geography, Federal University of Mato Grosso do Sul, Avenida Costa e Silva S/N, Cidade Universitária, Campo Grande-MS, Brazil ' Faculty of Engineering, Architecture and Urbanism and Geography, Federal University of Mato Grosso do Sul, Avenida Costa e Silva S/N, Cidade Universitária, Campo Grande-MS, Brazil

Abstract: Acidogenic fermentation (AF) of cassava wastewater was investigated with adapted and unadapted biomass with and without methanogenic inhibition techniques to enhance accumulation of volatile fatty acids (VFA) in batch tests. Subsequently, the possibility of VFA chain elongation for the production of medium-chain fatty acids (MCFA) by means of ethanol addition to the fermentation broth was evaluated. With unadapted sludge, 84.1% and 66.1% acidification could be obtained for thermally inhibited and non-inhibited conditions respectively, results 10% and 45% higher than the degrees of acidification obtained under the same conditions with adapted sludge. Results show that neither sludge adaptation nor heat treatment but rather the pH of the fermentation broth was most relevant for enhancing VFA production, the optimum pH range being 5.5 to 6. The main product was butyric acid (87% of total acid produced), and addition of ethanol to the fermentation broth promoted MCFA formation.

Keywords: anaerobic digestion; acidogenic fermentation; cassava wastewater; volatile fatty acids production; VFA; acidification degree; methanogenesis inhibition; heat shock; acidification; chain elongation; medium chain fatty acids; MCFA; ethanol; waste management.

DOI: 10.1504/IJEWM.2020.105353

International Journal of Environment and Waste Management, 2020 Vol.25 No.2, pp.245 - 261

Accepted: 03 Jan 2019
Published online: 04 Feb 2020 *

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