Continuous biohydrogen production by thermophilic dark fermentation of cheese whey: Use of buffalo manure as buffering agent

Biohydrogen (H2) production from dark fermentation processes is inhibited at low culture pH (<4.0). This work investigated the culture pH and H2 production stability during the dark fermentation of cheese whey, supplemented with buffalo manure. The co-fermentation of cheese whey, rich in high carbohydrate but yielding acidic pH, with buffalo manure characterized by a high alkalinity, is promising for continuous H2 production in dark fermentation. At a cheese whey to buffalo manure ratio of 4 g VS/g VS, a maximum H2 yield and production rate of respectively, 152.2 (±43.9) mL H2/g VS and 215.4 (±62.1) mL H2/L/d, were achieved at an organic loading rate of 2.1 g VS/L/d of cheese whey at a stable culture pH of 4.8–5.0. The use of buffalo manure improved the H2 production stability and could replace chemical buffering agents of scaled-up dark fermentation applications.