Florida Wastewater Practice Test

Which type of sludge is often considered for recycling in wastewater treatment?

1. Primary sludge

2. Activated sludge

3. Thickened sludge

4. Returned sludge

The correct answer is: Activated sludge

Activated sludge is a key component in many biological wastewater treatment processes and is often considered for recycling due to its role in enhancing the treatment efficiency and maintaining the microbial population necessary for breaking down organic matter. In the activated sludge process, microorganisms are used to decompose organic pollutants in wastewater. This process produces a mixture of microorganisms, which is referred to as activated sludge. The richness in active microorganisms makes this type of sludge particularly valuable, as it can be returned to the aeration basin to bolster the biological treatment process, thereby ensuring a consistent level of treatment performance. Recycling activated sludge not only helps in maintaining the desired concentration of microorganisms but also helps in improving the overall efficiency of the treatment system. The return of activated sludge aids in the retention of the microbial population, which is critical for the breakdown of organic material in incoming wastewater. In summary, the recycling of activated sludge in wastewater treatment processes is integral to the operation and effectiveness of biological treatment systems.