Lagoon Types and How Each One Works
A lagoon is not a simplified mechanical plant. It is a different technology with its own
biology, its own failure modes and its own operating levers. Knowing which type you have is the
first thing that determines what you can and cannot do about a problem.
Facultative (stabilization) ponds
The most common type at small systems. A facultative pond works in layers:
- An aerobic upper layer, oxygenated by two sources - natural reaeration at the surface and,
much more importantly, photosynthesis by algae.
- An anaerobic benthic layer at the bottom, where settled solids digest anaerobically.
- A facultative zone between them, where organisms work with or without oxygen.
The name comes from that middle zone. There is no mechanical aeration, so the oxygen supply is
biological and weather-dependent, which is why performance is seaso