Florida Wastewater Practice Test

What happens to the activity rate of activated sludge microorganisms when the wastewater temperature increases by 10°C?

1. It remains the same

2. It decreases

3. It doubles

4. It triples

The correct answer is: It doubles

When the temperature of wastewater increases by 10°C, the activity rate of activated sludge microorganisms typically increases due to enhanced metabolic processes. Microorganisms are generally more active at higher temperatures within their optimal range because the rate of biochemical reactions tends to increase with temperature. This phenomenon follows the general principle known as the Q10 rule, which states that for many biological processes, the rate of reaction approximately doubles for every 10°C increase in temperature, up to a certain maximum limit where enzymes may denature or cellular functions may be impaired. In the context of wastewater treatment, an increase in temperature promotes a higher synthesis of enzymes and metabolic processes essential for breaking down organic material. Therefore, the statement that the activity rate doubles is aligned with these biological principles observed in activated sludge systems. It's important to note that while the increase can be significant, extremes in temperature can eventually lead to detrimental effects on the microorganisms if temperatures rise too high.