Page 17 - Simplified Wastewater Treatment Fundamentals_Ponds and Lagoons PT1
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Stabilization Ponds & Sludge Lagoons
Facultative Sludge Lagoons
Facultative Sludge Lagoons are used to retain and digest sludge. Facultative
Sludge Lagoons are deeper than a Shallow Pond, providing a wider variety of
microorganisms, including aerobic bacteria located near the surface, which
depend on atmospheric oxygen.
Facultative bacteria are located at mid depth. Facultative bacteria can survive
breathing atmospheric oxygen, carbon dioxide, or the oxygen associated with
nitrite (NO2) and nitrate (NO3).
The bottom layer consists of anaerobic bacteria digesting the sludge. The clear
upper layer of a Facultative Sludge Lagoon is not normally discharged, but
instead evaporates. Facultative Sludge Lagoons must be dredged regularly to
manage sludge inventory.
