Hydrogen enrichment as a bioaugmentation tool to alleviate ammonia inhibition on anaerobic digestion of phenol-containing wastewater.

Phenol and ammonia are prevalent toxic pollutants in various industrial wastewaters, but phenol degraders are frequently inhibited by high concentration of ammonia. Hydrogen enrichment was developed to alleviate ammonia inhibition on anaerobic digestion of phenol-containing wastewater. Results indicated that the endurance to ammonia of sludge was improved greatly by hydrogen enrichment at higher ammonia concentration (from 2 to 8 g NH-N/L) compared with the control group. Furthermore, phenol utilization rate of sludge was gradually enhanced with the increase of initial hydrogen partial pressure (HPP) at ammonia concentration of 2 g NH-N/L and the maximum rate of 199.75 mg/g VSS/d was achieved under 0.8 atm HPP. The maximum SMA of acetate and hydrogen was 0.61 and 0.45 g COD-CH/g VSS/d, respectively under 0.8 atm HPP. Three hydrogen-consuming pathways including homoacetogenesis, hydrogenotrophic methanogenesis and benzoate generation played the critical roles in enhancing anaerobic digestion of phenol by hydrogen enrichment under high ammonia concentration.