This system generally discharges home sewage directly into the lagoon. Properly designed and sized lagoons use evaporation for dewatering. Both aerobic and anaerobic decomposition occur in lagoon treatment of home sewage. Anaerobic treatment generally occurs at and near the bottom of lagoons where settled solids and sludges accumulate. This treatment is similar to the anaerobic treatment that occurs in septic tanks.
Aerobic treatment occurs in the presence of oxygen and usually occurs near the lagoon surface.
Aerobic treatment aids in reducing the odors released during anaerobic treatment and also provides additional treatment of home sewage. Wind movement aids in mixing oxygen into the lagoon surface and helps to increase evaporation. Proper lagoon sizing and construction is essential for holding and treating home sewage. The surface area of a lagoon must be at least 900 square feet. When more than 5 people live in a house, an additional 175 square feet of lagoon surface area is required for each person.