What types of pumps are used in aeration basins?
Pumps used to mix the contents of the aeration basin need to handle wastewater solids, usually from the bottom of the aeration basin. Aeration basin solids can range from typically 0.1% to 0.5% (1,000 to 5,000 milligrams per liter [mg/L]) in conventional activated sludge processes, and can be up to 1% to 1.2% (10,000 to 12,000 mg/L) solids in membrane bioreactors.
There will be some stringy materials and grit but in the headworks portion of the plant. The pumps or pump system will operate continuously to mix the contents of the aeration basin. The pumps are usually low-head, high-volume units that can discharge directly into the basin usually above the water surface or may be coupled to an air induction unit to add air into the water.
Pumps in combination with Venturi-type air induction devices can be used to mix and aerate the mixed liquor. Either dry pit or submersible pumps can be considered for this use. Chopper-type pumps may be more applicable for this duty.
The following pump types can be considered for use in the aeration basin for mixing and aeration: dry pit and submersible rotodynamic type; submersible solids handling rotodynamic type (vertical wet pit or dry pit mounted either horizontally or vertically); and end suction chopper type.
For more information on wastewater treatment, refer to Wastewater Treatment Plant Pumps: Guidelines for Selection, Application, and Operation at pumps.org/standards.
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