Temperature • The temperature of the mixed liquor significantly affects the growth rate of the nitrifiers. Nitrifiers can grow within a wide temperature range, 4 °C to 50°C (39°F to 122 ° F); however, the optimum temperature range is 30 °C to 36°C (86°F to 97 ° F). • At temperatures below 10 °C (50 °F) if nitrification has been