Mainstream anammox reactor performance treating municipal wastewater and batch study of temperature, pH and organic matter concentration cross-effects

Abstract The anammox process is an energy efficient promising alternative to biologically remove the nitrogen. Thus, a 5-L anammox granular reactor was inoculated with sludge coming from a sidestream partial nitritation and anammox reactor (>200 mg N/L and 30 °C) and it was directly subjected to 15 ± 1 °C treating mimicked municipal wastewater (50 mg N/L). Results indicated that an acclimation period (commonly used) to progressive reach the mainstream conditions is not needed, shortening the start-up periods. The long-term anammox process stability was proved to treat synthetic wastewater with decreasing alkalinities and nitritified primary settled municipal wastewater. The low pH values (6.2 ± 0.1) of the municipal wastewater fed did not affect the process stability. Residual organic matter concentrations augmented the nitrogen removal efficiency from 80 % (with the synthetic medium) to 92 % achieving effluent concentrations below 10 mg TN/L. Finally, the effect of pH (6 - 8), temperature (15 - 30 °C) and organic matter concentration (0 - 75 mg TOC/L) over the specific anammox activity (SAAMX) was evaluated at short-term. pH and temperature and their interactions exerted significant influence on the SAAMX value while the TOC concentrations itself did not significantly change the SAAMX.