Reactor start-up strategy as key for high and stable hydrogen production from cheese whey thermophilic dark fermentation

Using the right start-up strategy can be vital for successful hydrogen production from thermophilic dark fermentation (55 degrees C), but it needs to be affordable. Hence, three start-up strategies modifying only influent concentration and temperature were assessed in a reactor fed with cheese whey: (i) high temperature (55 degrees C) and a high organic loading rate (OLRA - 15 kgCOD m(-3) d(-1)) right at the beginning of the operation; (ii) slowly increasing temperature up to 55 degrees C using a high OLRA and (iii) slowly increasing temperature and OLR(A )up to the desired condition. Strategy (iii) increased hydrogen productivity in 39% compared to the others. The combination of high temperature and low pH thermodynamically favored H-2 producing routes. Synergy between Thermoanaerobacterium and Clostridium might have boosted hydrogen production. Three reactors of 41 m(3) each would be needed to treat 3.4 x 10(3) m(3) year(-1) of whey (small-size dairy industry) and the energy produced could reach 14 MWh month(-1). (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.