Abstract: | 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. |