Temperature Correction (Θ) Calculator
Biological rates slow down in cold water. Enter your 20 °C rate constant and the process temperature to get the temperature-corrected rate used in design equations.
Temperature-Corrected Rate
| Item | Value |
|---|
How the calculation works
Formulas
kT = k20 × θ(T − 20), T in °C
Correction factor = θ(T − 20)
kT = k20 × θ(T − 20), T in °C
Correction factor = θ(T − 20)
| Process | Typical θ |
|---|---|
| Carbonaceous BOD removal | 1.047 |
| Nitrification | 1.12 |
| Denitrification | 1.09 |
Notes & limitations
The Arrhenius-style theta correction and these textbook theta values are from Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (1.047 for BOD, 1.12 for nitrification). Use the theta that matches the rate constant’s source — literature values vary by study.
- Theta values are empirical and study-specific; a published k₂₀ is only valid with the theta from the same source.
- The correction assumes the same rate-limiting biology across the temperature range — near freezing or above ~35 °C, verify against pilot or plant data.
- This corrects the rate constant only; design must also account for lower oxygen transfer and higher viscosity in cold water.
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