Enhancement of biohydrogen production rate in Rhodospirillum rubrum by a dynamic CO-feeding strategy using dark fermentation

Table 4 Experimental results of the fed-batch runs performed under several CO-feeding strategies

CO-feeding strategy	Operation time (days)	Liquid phase			Gas phase
		Total C_X (g l⁻¹)	PHB (%) (w w⁻¹)	Acetate conversion (%)	Avg. production–consumption rates (mmol l⁻¹ h⁻¹)
		Total C_X (g l⁻¹)	PHB (%) (w w⁻¹)	Acetate conversion (%)	CO	H₂	CO₂
Constant (p_CO = 0.60 atm)	19.8	5.35	27.6	76.6	39.2	32.3	13.4
Dynamic (from 0.1 to 0.75 atm, enriching gas flow)	10.8	4.28	24.9	91.4	29.1	27.2	15.3
Dynamic (from 0.1 to 2 atm, increasing working pressure)	13	3.95	20.8	83.2	24.3	25.1	15.4

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