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REVIEW OF LAGOON OPERATION
Technical Note 1
Lagoons are frequently used to treat sewage generated by a town or industry. They are an enhancement of natural treatment of waste products and are considered to be low-tech. The objective of a lagoon or other type of wastewater treatment system is to stabilize the organic material and other matter that makes up the waste stream so that it no longer exerts an oxygen demand on our streams and lakes. Lagoons can meet this objective if properly maintained and managed.
Lagoons come in many forms and shapes, but they all have some common characteristics depending upon the type of treatment that is desired.
Most lagoons begin operation as facultative lagoons. That is, they have a layer at the top of the water that is aerated naturally by wind and wave action. This layer is described as aerobic because the micro-organisms that dwell there require oxygen to function properly. The bottom layer contains micro-organisms that function without oxygen and are called anaerobes. In between these two layers is a section that contains micro-organisms that can function with or without oxygen. Facultative lagoons are generally 4-8 feet deep and have long detention times.
Anaerobic lagoons operate almost entirely without oxygen. They work like a large septic tank. Frequently they are used to treat high oxygen-demanding domestic or industrial waste.
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