Thermophilic biohydrogen production from glucose with trickling biofilter

Thermophilic H2 production from glucose was studied at 55-64 degrees C for 234 days using a continuous trickling biofilter reactor (TBR) packed with a fibrous support matrix. Important parameters investigated included pH, temperature, hydraulic retention time (HRT), and glucose concentration in the feed. The optimal pH and temperature were 5.5 and 60 degrees C, respectively. With decreasing HRT or increasing inlet glucose concentration, volumetric H2 production rate increased but the H2 production yield to glucose decreased gradually. The biogas composition was almost constant at 53 +/- 4% (v/v) of H2 and 47 +/- 4% (v/v) of CO2. No appreciable CH4 was detected when the reactor was under a normal operation. The carbon mass balance showed that, in addition to cell mass, lactate, n-butyrate, CO2, and acetate were major products that comprised more than 85% of the carbon consumed. The maximal volumetric H2 production rate and H2 yield to glucose were 1,050 +/- 63 mmol H2/l.d and 1.11 +/- 0.12 mol H2/mol glucose, respectively. These results indicate that the thermophilic TBR is superior to most suspended or immobilized reactor systems reported thus far. This is the first report on continuous H2 production by a thermophilic TBR system.