The evolution of Anammox performance and granular sludge characteristics under the stress of phenol.

Abstract The short- and long-term effects of phenol on anaerobic ammonium oxidation (Anammox) were evaluated. The short-term impact of phenol on Anammox activity was determined by a batch test, and an IC 50 value of 678.2 mg L −1 was calculated. Anammox granular sludge was equally seeded into two identical upflow anaerobic sludge blanket reactors ( R 0 and R 1 ); synthetic wastewater without phenol was fed to R 0 while with varied phenol was fed to R 1 to study the long-term effects. The performance of R 0 was stable, with a steadily rising nitrogen removal rate of 10.5–21.3 kg N m −3  day −1 . However, the performance of R 1 was significantly suppressed by an influent phenol concentration of 50 mg L −1 , and was recovered and stabilized by applying one or more control strategies. The phenol-mediated inhibition depressed the Anammox activity and biomass, and caused a change of stoichiometric ratios and granule characteristics.