Fig. 6From: Potential of acetic acid to restore methane production in anaerobic reactors critically intoxicated by ammonia as evidenced by metabolic and microbial monitoringProgress over time of the concentration of C3 to C5 volatile fatty acids in the slurry for: a the free ammonia intoxicated reactor, HNR1, b HNR2 and c HNR3. The valerate (C5) concentration was below the detection limit of the analytical method during the whole experiment. “Process reconditioning I, II, III”, “Process recovery” and “Process stability test” refer to the phases described in Table 1Back to article page