Following preliminary treatment, wastewater enters three primary settling
tanks which reduces flow velocity and provides a condition for the settling of solids that are denser than water. The
solids that settle are collected as primary (or raw) sludge and is
pumped to degritting equipment in the thickener building. The
separated grit is sent to the landfill and the degritted sludge flows
to the gravity thickeners for further treatment. Solids that remain in
suspension or are dissolved in the wastewater then flow to further
treatment processes.