Ozonation Strategies to Maximize Bio-Hydrogen and Volatile Fatty Acid Production in Dark Co-Fermentation Process

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ABSTRACT Organic waste treatment through co-fermentation presents a promising approach for biogas production and the generation of valuable compounds. However, wastes like sewage sludge (SS) and wine vinasse (WV) have inherent limitations that hinder process efficiency. This study aimed to optimize the thermophilic dark co-fermentation (55°C) of SS and WV at a 50:50 volume ratio by employing ozone pre-treatment to enhance bio-hydrogen and volatile fatty acid (VFA) production. Two ozonation strategies were evaluated: ozonation of the SS/WV mixture (SSO/WVO) and ozonation of SS followed by WV addition (SSO/WV), using an optimized ozone dose of 0.018 g O3/g TS0. Key parameters, including dissolved organic carbon (DOC), total acidity, total volatile fatty acids (TVFAs), and bio-hydrogen production, were analyzed. The findings revealed that the SSO/WV strategy significantly increased DOC and TVFA yields, particularly short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) such as butyric and valeric acids. This strategy resulted in a 370% increase in TVFAs and a 50% enhancement in bio-hydrogen production compared to untreated controls. In conclusion, ozone pre-treatment, especially the SSO/WV strategy, effectively enhanced VFA and bio-hydrogen yields during SS/WV co-fermentation. This approach provides a promising pathway to optimize the conversion of organic waste into high-value products, with notable implications for agro-industrial waste management and bioenergy production.