Transient temperature effects on biofilters in recirculating systems ammonia removal rates

Biofilter response was determined as the capability to utilize total ammonia nitrogen (TAN) by ammonia oxidizing bacteria (AOB). Tau (τ) values for ammonia oxidation were 40.73 day−1, 58.81 day−1 and 159.70 day−1 at 13 °C, 20 °C and 30 °C respectively. Total ammonia nitrogen substrate utilization rates as indicated in a decay plot differed significantly (P < 0.05) between temperature regimes 20 and 30 °C. However substrate utilization between 13 and 20 °C were not different (P > 0.05). Ammonia oxidation tau values were 118.20 day−1 and 223.50 day−1 at (20 ± 3 °C) and (30 ± 3 °C) diurnal temperatures respectively. These were significantly different (P < 0.05). The data in this study can be applied to future seeded or acclimating biofilters operating within these temperature ranges.