Aerobic treatment units treat wastewater for homes and small businesses using the same process, only scaled down, as our municipal wastewater treatment systems use. They remove 85 to 98 percent of the organic matter and solids from the wastewater, producing effluent as clean as that from municipal wastewater treatment plants, and cleaner than that from conventional septic tanks.
Aerobic units, which are certified as Class I aerobic systems, treat wastewater well enough to be used in conjunction with spray systems, which distribute treated wastewater over lawns. They are the most common way to treat wastewater for spray systems.
The aerobic treatment process includes four main components that work together to purify wastewater:
- A pretreatment tank, generally referred to as the “trash tank” because it removes materials that microorganisms (microbes) cannot degrade.
- An aeration chamber, where aerobic microbes decompose waste in the water. An aeration system consists of an air pump, piping and diffusers that force air into the aeration chamber. The air pump, located near the aerobic tank, compresses air to flow into the aeration chamber. The diffuser forces the air into the water, dividing the air into bubbles that float to the surface. The oxygen in the air bubbles goes into the water for the microbes, while the rising bubbles mix with the wastewater.
- A settling chamber, commonly called a clarifier, which provides a place for the microbes that have treated the wastewater to settle out of the water.
- A final treatment and dispersal component, which distributes the water into the soil for reuse. Aerobic treatment units usually disperse wastewater via a spray field, which includes a disinfection component for removing disease-causing microorganisms, a pump tank for dosing water, and distribution heads for spreading the water over the ground.