Currently, in the pilot-scale SBRs (Sequencing Batch Reactors) nitritation of reject water from sludge dewatering is carried out. The influent is reject water from digested sludge dewatering process, which is characterized by elevated temperature, high ammonium concentration, and low organic matter content. The activated sludge grown under these conditions shows several times higher dynamics of ammonium nitrogen removal than in conventional activated sludge process treating municipal wastewater. Moreover, the process is carried out at a much lower pH causing almost complete inhibition of nitration. Furthermore, the ammonia oxidizers enriched in this reactor will be more resistant to elevated free nitrous acid and free ammonia concentrations.
