Lagoons eventually fill, then overflow after two to three years unless the contents are periodically removed and sprayed onto field crops, grassland or woodlots. Lagoons function as digesters in which aerobic or anaerobic bacteria decompose organic matter into gases, liquids and sludges. A naerobic lagoons are most common for livestock waste treatment because they require less surface area than aerobic lagoons and anaerobic bacteria can decompose more organic matter per unit lagoon volume than aerobic bacteria. Sometimes odor problems can occur with anaerobic lagoons. A erobic lagoons can be naturally aerobic or mechanically aerated.
Bacterial digestion is more complete, making the lagoon odor-free.
Aerobic lagoons require more surface area so that oxygen can freely enter the water. Algae often helps the process. O ne possibility for livestock waste after digestion in a lagoon is application to a constructed wetland. Nutrients and sediment are removed from water that flows into wetlands. Roots and stems in the water facilitate bacterial growth and filter and absorb solids.