Primary Clarifiers

 

The flow from the influent structure is split between two, rectangular primary clarifiers. The clarifiers provide the next treatment step by removing most of the settleable solids. To accomplish this, the movement of the wastewater is slowed down to the point that heavier solids settle to the bottom of the tank, and lighter-than-water materials, such as oil and grease, float to the top. The floating materials are skimmed off, and the bottom settlings are continuously scraped to a hopper and periodically drained off. The skimmings and settled solids, called sludge, are pumped to the aerated sludge lagoon.