The next phase of treatment is designed to remove the finer particles in the wastewater stream. This process takes place in the aeration basins and is called secondary treatment. Here, the water is mixed with "Activated Sludge," which is a mixture of microorganisms (good bugs) that feed on the fine sludge particles and contaminants. All the bugs need is food (the contaminants or organic materials from the wastewater) and oxygen (which is supplied through diffusers or bubblers at the bottom of the tank, much like a fish tank). This process takes about five hours to complete, and then the water continues on to the secondary clarifiers.

Activated Sludge Basin

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