Iglesias Riobó, JuanBalboa Méndez, SabelaBevilacqua, RiccardoMauricio Iglesias, MiguelCarballa Arcos, Marta2024-07-052024-07-052024Journal of Water Process Engineering Volume 64, July 2024, 105689http://hdl.handle.net/10347/34342This work investigates how several marine salt levels typical of canning industry wastewaters (0, 10, 15, 20, and 35 g salt/L), mainly composed of proteins and sugars, impact the production of volatile fatty acids (VFAs), their selectivity and the acidogenic microbiome. Mixed-culture fermenters were operated in continuous (25 °C, pH =7; HRT 1.5 d) and batch (25 °C, pH = 7, substrate-to-inoculum ratio 20 g COD/g VSS) regime. Low salinity levels (0–10 g/L) led to high VFA yields (74 %, COD basis), dropping to 46 % at higher salt concentrations. Acetic acid was always the main product (> 67 % molar basis), and butyric and valeric acid concentrations were negatively affected by high salinities (20–35 g/L). Salinity changes were also reflected in the microbial population: Clostridia was the dominant class in the whole salinity range although Actinobacteria increased its relative abundance as salinity increased. The experimental results were consistent with salt-in osmoregulation at low and medium salinities (0–15 g/L) while the compatible solutes strategy appears as more likely at high salinities (20–35 g salt/L). Given the needs for compatible solute strategy, these results enable the selection of co-substrates complementing wastewaters at the high salinity range to enhance the VFA production.eng© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND licenseAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Anaerobic fermentationCarboxylate platformOsmoregulation mechanismsCompatible-solutesSalt-injournal article10.1016/j.jwpe.2024.1056892214-7144open access