Fig. 2.

Reactor performance during the continuous operation of 199 days. a Cumulative CO consumption in mmol. b Cumulative gas production of CO₂, H₂, and CH₄ in mmol. c DOC (dissolved organic carbon) and DIC (dissolved inorganic carbon). d DN (dissolved nitrogen). e pH and ORP (oxidation–reduction potential). The blocks labeled with I, II, III, IV, V, VI and VII indicate the seven phases during continuous feeding