Tennessee Wastewater Operator Practice Exam

What method is recommended for controlling the activated sludge process?

1. Sludge age

2. Flow rate

3. Temperature regulation

4. pH adjustment

The correct answer is: Sludge age

The recommended method for controlling the activated sludge process is sludge age, also known as mean cell residence time (MCRT). This parameter is vital in determining the health and efficiency of the biological treatment process. Sludge age allows operators to assess and adjust how long microorganisms remain in the system before being removed as waste. When sludge age is appropriately managed, it ensures that there are enough active microbes in the system to effectively break down organic matter and remove pollutants from wastewater. A longer sludge age can enhance the treatment process by allowing more time for microbial growth, leading to better stabilization of the sludge and improved removal of nutrients such as nitrogen and phosphorus. Conversely, a shorter sludge age may lead to insufficient microbial populations, resulting in poor treatment performance. Other methods like flow rate, temperature regulation, and pH adjustment also affect the activated sludge process, but they do not directly control the biological activity in the same way that sludge age does. Managing the flow rate helps with hydraulic retention times but does not focus specifically on microbial populations. Similarly, while temperature and pH can influence microbial activity, they are not as fundamental to controlling the overall performance of the activated sludge process as sludge age is.