Influence of temperature on the activity of anammox granular biomass

The aim of this study was to determine a short-term and long-term effect of temperature on the anammox rate and determination of temperature coefficients in the Arrhenius and Ratkowsky equations. The short-term effects of temperature on the anammox granular biomass were investigated in batch tests at ten different temperatures in the range of 10-55 degrees C. The maximum overall nitrogen removal rate of 1.3 gN gVSS(-1).d(-1) was observed at 40 degrees C (VSS: volatile suspended solids). The minimum rate, close to 0 gN gVSS(-1).d(-1), was observed for the limits of the analyzed temperature range (10 and 55 degrees C). The activity tests carried out at 55 degrees C showed an irreversible loss of the activity due to the observed biomass lysis. Subsequently to the batch tests, a sequencing batch reactor (SBR) was operated at different temperatures (from 30 to 11 degrees C) to determine the long-term effects of temperature. The system was successfully operated at 15 degrees C, but when temperature was decreased to 11 degrees C, nitrite started to accumulate and the system lost its stability. The temperature coefficient (theta) was 1.07 for the batch tests carried out in the temperature range of 10-40 degrees C. In contrast, during the long-term SBR operation, substantially different theta had to be estimated for two temperature ranges, 1.07 (T = 15-30 degrees C) and 1.65 (T = 11-15 degrees C).