What will be present in a clarifier if the passages connecting stages are located near the bottom?

In a clarifier, the arrangement and location of passages connecting different stages play a crucial role in determining what materials will be present. When these passages are located near the bottom, it facilitates the movement of heavier materials, like sludge and sand, towards the bottom of the clarifier.

The design that places the connections low means that lighter materials—such as oils and other floatables—are likely to remain near the top of the clarifier, where they can be more easily separated and removed. This is due to the principle of density differences, where lighter substances rise and heavier substances sink. Therefore, in this scenario, floatable materials (like oil) would be more prominent at the surface level since they tend not to mix with heavier sediments that are settled below.

Sandy sediments and heavy metals, while being present in a clarifier, would typically settle at the bottom, where heavier components accumulate. Excessive sludge, on the other hand, refers to a condition that indicates a problem rather than a natural function of the clarifier based on its construction. As a result, since oil and other floatable substances are influenced by this specific design, they are the correct focus in understanding what would be found in such a clarifier arrangement with the connections near