Hydrogen production from (cane-molasses) stillage by citrobacter freundii and its use in improving methanogenesis

Citrobacter freundii is a facultatively anaerobic fermentative organism capable of H₂ production from sugars and lactate. A locally isolated strain of C. freundii was shown to be capable of H₂ production on an equimolar basis (i.e. 1:1.2 mol/mol) from glucose. It was also found capable of H₂ production from cane-molasses stillage (having BOD₅ of 54 kg m^?3) at a rate of 1.2 m³ (m³waste) ¹ day^?1. This was tested on various scales, ranging from 0.06 to 100 1 and was found to be consistent over these variations in scale. Simultaneously, the BOD₅ value was reduced at a rate of 5.4 kg (m³waste)^?1 day^?1.

One of the uses of the evolved H₂ was as feed for an anaerobic digestor containing (untreated) cane-molasses stillage as substrate. With this arrangement, the methanogenesis was enhanced by way of increased production of methane (i.e. rise in volumetric methane content of the evolved gas), while added H₂ vanished totally from the digestor. The question of whether microbially produced H₂ can be used more profitably in microbial utilization of H₂ for energy production is considered in detail.