Hydrogen production from the anaerobic treatment of vinasses in a UASB reactor

Fermentative hydrogen production from sugar-cane vinasses was evaluated in a 3-L UASB reactor under mesophilic conditions. The seed sludge, taken from an industrial wastewater UASB reactor, was heat treated to inhibit non hydrogen producing bacteria. Hydrogen producing granules were first formed in a CSTR reactor and then transferred to the UASB reactor. Operating under mesophylic (37 degrees C) conditions, pH close to 5.5, inlet substrate concentration of 20 000 mg COD/L, and hydraulic retention time (HRT) of 6 hours, the average hydrogen production rate obtained in the UASB reactor was 1,68 mL H-2/h/L, showing a maximum value of 13,4 mL H-2/h/L. COD removal in the fermentation process reached maximum values of 43%, with an average value close to 20%. Both, hydrogen production and COD removal showed inverse dependence on HRT. The results obtained in this study show that anaerobic fermentation of vinasses using a UASB reactor is a feasible way to sustainably produce molecular hydrogen.