Assessment of Biohydrogen Production Potential of Anaerobic Sludge Consortium and Clostridium acetobutilycum Strain 6441 via Dark Fermentation of Cheap Carbohydrate

Abstract

The hydrogen production potential of Clostridium acetobutylicum strain 6441 and heat treated anaerobically digested sludge consortium (ADS) was studied. The inoculums’ ability to metabolize some cheap substrates while producing hydrogen was used as assessment factors. Environmental conditions for the cultures were the same having a starting pH of 6.0 and a temperature of 35^oC. Growth kinetics, volumetric hydrogen production rate and the rate of catabolism of the sugars was studied. C. acetobutyricum showed greater production potential and metabolic plasticity; having a hydrogen production rate of 5.29, 1.337 and 1.058 mlh^-1 and a substrate utilization rates of 149.7, 92.89 and 180.1 mgl^-1h^-1 from glycerol, xylose and lactose respectively. ADS on the other hand, showed hydrogen production rates of 1.476, 1.017 and 0.290 mlh^-1 and substrate utilization rates of 56, 22.35 and 35.59 mgl^-1h^-1 from glycerol, xylose and lactose respectively. Upon scale up, a total of 19.8% and 11.297% hydrogen was produced via the fermentation of crude (untreated) glycerol and pure glucose using C. acetobutylicum and ADS respectively. The study revealed C. acetobutylicum and glycerol to have a greater hydrogen production potential than ADS and other substrates. More work was suggested to optimize the production potential of ADS since it is preferred to pure cultures for reasons of sterilization and energy cost.

Keywords: biohydrogen, Dark fermentation, Crude glycerol, Lignocellulosic biomass, UASB, Anaerobically digested sludge