What should the concentration of solids be in the lower level of sludge in a softening facility solid contact basin?

In a softening facility solid contact basin, the lower level of sludge is typically expected to have a concentration of solids in the range of 5-15%. This concentration is ideal for maintaining effective sludge density and ensuring adequate contact between the sludge and the influent water, which promotes effective coagulation and removal of hardness.

At this concentration, the sludge can effectively settle, allowing for optimal performance in the removal of impurities and ensuring that the water treatment process is efficient. A concentration lower than 5% may indicate insufficient solids for optimal reaction and settling, leading to reduced effectiveness in treating the water. Conversely, a concentration exceeding 15% can create challenges with the settling process, possibly resulting in problems with sludge handling or reducing the overall efficiency of the softening process. Therefore, 5-15% is the targeted range, allowing for a balance between effective treatment and operational efficiency.