Long-term Impact of Low Temperature on Anammox Process

Implementation of anammox in the mainstream treatment is a prerequisite to energy net positive WWTP. Impact of long-term exposure to the low mainstream temperature (i.e.10°C) on the anammox process was investigated. Process was run in MBR configuration using anammox biomass enriched in mesophilic conditions. Temperature in the reactor was reduced from 34 to 10°C over 24 days. Relatively high specific nitrogen removal rate of 113 and 71 mg N/g VSS·d was observed after six days of operation at 16°C and 10°C, respectively. This corresponded with total nitrogen removal efficiency of 88±2% achieved in the range of temperature between 34 and 10°C. Results indicate that mesophilic biomass may be used in the mainstream process in moderate and colder climates; however, prolonged operation at ≤10°C may lead to complete loss of anammox activity. PCR allowed us to follow the population dynamics of 3 different strains of Brocadia throughout the time course.