Tennessee Wastewater Operator Practice Exam

What is the typical solids concentration of primary sludges?

1. 1-2%

2. 3-6%

3. 7-10%

4. 10-12%

The correct answer is: 3-6%

The typical solids concentration of primary sludge is around 3-6%. This concentration range is common in wastewater treatment facilities, where primary sludge is generated from the sedimentation process during the treatment of raw sewage. In the primary treatment stage, solid materials settle out of the wastewater, creating a mixture that consists of both liquid and solids. The solids that form are referred to as primary sludge, and they typically have a concentration that allows for effective handling and further processing. Understanding this range is important for wastewater operators, as it impacts the subsequent treatment processes, such as digestion and dewatering. If the solids concentration is either too low or too high, it can disrupt the efficiency of these operations, affecting the overall treatment performance and the quality of the effluent being released. Therefore, knowing that the usual concentration is within the 3-6% range helps operators manage their processes effectively.