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

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 IC50 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. (C) 2013 Elsevier Ltd. All rights reserved.