Dark fermentation of sweet sorghum stalks, cheese whey and cow manure mixture: effect of pH, pretreatment and organic loadDark fermentation of sweet sorghum stalks, cheese whey and cow manure mixture: effect of pH, pretreatment and organic load Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2022-11-182021enThis research was co-funded by the European Union (European Social Fund—ESF) and Greek national funds through the Operational Program “Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF)—Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund.The aim of this study was to determine the optimal conditions for dark fermentation using agro-industrial liquid wastewaters mixed with sweet sorghum stalks (i.e., 55% sorghum, 40% cheese whey, and 5% liquid cow manure). Batch experiments were performed to investigate the effect of controlled pH (5.0, 5.5, 6.0, 6.5) on the production of bio-hydrogen and volatile fatty acids. According to the obtained results, the maximum hydrogen yield of 0.52 mol H2/mol eq. glucose was measured at pH 5.5 accompanied by the highest volatile fatty acids production, whereas similar hydrogen productivity was also observed at pH 6.0 and 6.5. The use of heat-treated anaerobic sludge as inoculum had a positive impact on bio-hydrogen production, exhibiting an increased yield of 1.09 mol H2/mol eq. glucose. On the other hand, the pretreated (ensiled) sorghum, instead of a fresh one, led to a lower hydrogen production, while the organic load decrease did not affect the process performance. In all experiments, the main fermentation end-products were volatile fatty acids (i.e., acetic, propionic, butyric), ethanol and lactic acid. http://creativecommons.org/licenses/by/4.0/Processes96Dareioti_et_al_Processes_9(6)_2021.pdfChania [Greece]Library of TUC2022-11-18application/pdf1.5 MBfree Dareioti Margarita A. Vavouraki Aikaterini Βαβουρακη Αικατερινη Tsigkou Konstantina Zafiri Constantina Kornaros Michael MDPI Agro-industrial wastes Dark fermentation Cheese whey Ensiled sweet sorghum Cow manure pH effect Organic load effect Pretreatment effect