title: An investigation of moving bed biofilm reactor nitrification during long-term exposure to cold temperatures.
abstract: Biological treatment is the most common and economical means of ammonia removal in wastewater; however, nitrification rates can become completely impeded at cold temperatures. Attached growth processes and, specifically, moving bed biofilm reactors (MBBRs) have shown promise with respect to low-temperature nitrification. In this study, two laboratory MBBRs were used to investigate MBBR nitrification rates at 20, 5, and 1 degree C. Furthermore, the solids detached by the MBBR reactors were investigated and Arrhenius temperature correction models used to predict nitrification rates after long-term low-temperature exposure was evaluated. The nitrification rate at 5 degrees C was 66 +/- 3.9% and 64 +/- 3.7% compared to the rate measured at 20 degrees C for reactors 1 and 2, respectively. The nitrification rates at 1 degree C over a 4-month exposure period compared to the rate at 20 degrees C were 18.7 +/- 5.5% and 15.7 +/- 4.7% for the two reactors. The quantity of solids detached from the MBBR biocarriers was low and the mass of biofilm per carrier did not vary significantly at 20 degrees C compared to that after long-term exposure at 1 degree C. Lastly, a temperature correction model based on exposure time to cold temperatures showed a strong correlation to the calculated ammonia removal rates relative to 20 degrees C following a gradual acclimatization period to cold temperatures.
authors.forename: Valerie
authors.initials: V
authors.lastname: Hoang
authors.forename: Robert
authors.initials: R
authors.lastname: Delatolla
authors.forename: Edith
authors.initials: E
authors.lastname: Laflamme
authors.forename: Alain
authors.initials: A
authors.lastname: Gadbois
mesh_terms: D000641:Ammonia / Q000302:isolation & purification*; D018441:Biofilms; D019149:Bioreactors; D003080:Cold Temperature; D058465:Nitrification; D062065:Wastewater / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D000641:Ammonia; D062065:Wastewater; D014874:Water Pollutants, Chemical