VARIATION OF CARBON-MONOXIDE PRODUCTION DURING METHANE FERMENTATION OF GLUCOSE

Carbon monoxide (CO) production in continuous stirred tank reactors (CSTRs) following perturbations with glucose, formate, or acetate was the focus of this study. Although reactors were operated in a similar manner, CO concentration following perturbations with substrate increased above detection limits in some reactors, but not in others. Where detectable, CO concentration appeared to increase in an unpredictable fashion with increases in acetate, formate, and possibly H-2 concentrations. With one mixed culture, CO concentration increased from 0.051 Pa(0.5 X 10(-6) atm) to only 0.41 Pa (4 X 10(-6) atm) when acetate concentration was increased to 20 mM, but increased no further with acetate increase to 60 mM. During formate perturbations with one culture, CO increased to a very high value of 25 Pa (250 X 10(-6) atm), a concentration near thermodynamic equilibrium with the added formate. However, in another mixed culture operated under similar conditions, the addition of similar acetate and formate concentrations resulted in formation of barely detectable CO concentrations (about 0.05 Pa), Such inconsistencies in CO production following substrate perturbations, even under similar conditions of operation, suggest that CO is not a useful monitoring parameter for the control of anaerobic treatment.