Averett Septic Tank Co Inc. > Septic Pumping Blog > ATU Systems: What are They and How Do They Work?

ATU systems treat waste aerobically

ATU systems offer an alternative to your typical septic system. So, what are they and how do they work? ATU stands for Aerobic Treatment Unit. As you can probably guess from the name, ATU systems treat waste aerobically instead of anaerobically like your typical septic system. Aerobic bacteria actually work faster than anaerobic bacteria, but they require oxygen. So, an ATU system requires that oxygen be injected into the tank. In order to provide the necessary oxygen for the aerobic breakdown process to happen, electricity is required. That is the biggest downside to ATU systems—since they require oxygen and electricity and they have more functioning parts, they require more upkeep and maintenance than a traditional septic system.

However, ATU systems are a great option for some homeowners depending on their situation. They don’t require a drain field like a septic system, making it possible to build homes on smaller lots or land that is forested without having to clear a large area. Let’s take a quick look at the components of an ATU system to better understand how they work:

  • Pretreatment Tank-The main sewer line from your house empties into this tank. This is where solid waste remains while the effluent (liquid wastewater) continues to the ATU.
  • Aerobic Treatment Unit (ATU)-This is where the magic happens. And by magic we mean the aerobic bacteria breaking down waste particles in the water. Oxygen is injected into this unit to create the aerobic process. Usually the water will continue to a clarifying chamber or go through a chlorinator for further purification before entering the pump tank.
  • Pump Tank-After being treated, water enters the pump tank and is then distributed onto the soil through an irrigation system (sprinklers or drip irrigation). The microbes in the soil finish the purification process and the water returns to groundwater to be used again.