Kinetic analysis of attached growth nitrification in cold climates

Abstract

The rate of nitrification within a laboratory-scale Biological Aerated Filtration treatment system at 48C was investigated during an exposure time of approximately four months (acclimatized experiments). In addition, shock experiments from 208C to 48C and from 48C to 208C were performed. The acclimatized experiments demonstrated that the exposure time the system remained at low temperature strongly affects the rates of nitrification. Nevertheless, the experiments showed that significant nitrification rates are maintained for up to 115 days at 48C.The rate of ammonia removal after an exposure time of 115 days at 48C was shown to be as high as 16% of the rate of removal observed at 208C. The 208C to 48C shock experiment demonstrated a 56% decrease in the rate of ammonia removal. On the other hand, the 48C to 208C shock experiment demonstrated an increase in the relative rates of ammonia removal of up to 300% when compared to rates of removal measured after 115 days at 48C. Thus, although the rates of nitrification have been shown to decrease significantly as a function of exposure time at 48C, the process has demonstrated important rates of ammonia removal at 48C for the approximate span of the North American winter.

An Investigation of Moving Bed Biofilm Reactor Nitrification during Long‐Term Exposure to Cold Temperatures

“…The traditional 0 values resulted in high predicted rates and, as such, the Delatolla et al (2009) 9 model was investigated and showed a strong correlation to the measured relative ammonia removal rates throughout various stages of the experiments, where the 9 value changes with exposure time. Furthermore, it should be noted that the Delatolla et al (2009) 9 model showed a stronger correlation relative to rates of removal after an acclimatization period compared to after rapid temperature changes. (10614303) is the property of Water Environment Federation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission.…”

“…The model provides a relative removal rate predicted for both reactors at 1 °C of approximately 19% and demonstrates a strong correlation to the measured data with time as opposed to the traditional theta model that provides a single removal rate at a given temperature. The R^ values for the Delatolla et al (2009) 9 model following the acclimatization period were 0.86 for Rl and 0.84 for R2, while the R^ values decreased to 0.68 and 0.82 for Rl and 0.63 and 0.41 for R2 during the first and second temperature shock events, respectively (Table 3). Therefore, the Delatolla et al (2009) 9 model performed best affer an acclimatization period compared to shock temperature changes.…”

“…The R^ values for the Delatolla et al (2009) 9 model following the acclimatization period were 0.86 for Rl and 0.84 for R2, while the R^ values decreased to 0.68 and 0.82 for Rl and 0.63 and 0.41 for R2 during the first and second temperature shock events, respectively (Table 3). Therefore, the Delatolla et al (2009) 9 model performed best affer an acclimatization period compared to shock temperature changes.…”

“…Furthermore, exposure time to temperatures below 5 °C following the acclimatization period has resulted in increasing 9 values as the exposure time progresses (Delatolla et al, 2009). Delatolla et al (2009) showed that 9 values for an attached growth BAF system exposed to 4 °C ranged between 1.002 at initial exposure to cold conditions and increased to 1.216 after 115 days of exposure. Thus, the following equation was formulated to correlate to the change in kinetics with exposure to cold conditions: 9 = 3.81 X 10"^ ln(i) + 9.83 X (4)…”

“…The Delatolla et al (2009) 9 model includes changing 9 values as the time of exposure changes (eq 4). As such, the Delatolla et al (2009) 9 model was used to simulate the corresponding relative removal rates measured in this study. The model provides a relative removal rate predicted for both reactors at 1 °C of approximately 19% and demonstrates a strong correlation to the measured data with time as opposed to the traditional theta model that provides a single removal rate at a given temperature.…”