Aerobic vs. Anaerobic Septic Tank System

Aerobic vs. Anaerobic Septic Tank System

The basic difference between aerobic and anaerobic septic tank  systems is the presence or absence of oxygen. Traditional anaerobic septic systems operated in underground tanks and in the relative absence of oxygen. This meant that the bacterial colonies that break down sewage must be able to live without oxygen. Although most aerobic septic tanks are also located underground, they depend on a mechanism called an “aerator” to inject oxygen into the tank from outside. Aerobic septic systems are thus able to support aerobic forms of bacteria.

aerobic digestion tank


Aerobic bacterial colonies are generally regarded as better for on-site wastewater treatment. According to the Food and Agriculture Organization of the United Nations, aerobic bacteria are less susceptible to household chemicals than anaerobic bacteria. Aerobic bacterial colonies are also better at breaking down human waste than anaerobic bacteria. However, aerobic bacteria are less able to break down inorganic solids, so aerobic systems may become clogged more easily. Aerobic bacteria also require constant aeration, so lengthy power outages can harm bacterial colonies in aerobic systems.

Small Septic Tank

Drain Field Requirements

A drain field is a component of s septic system that receives partially-treated wastewater from the septic tank and distributes it evenly to the soil through pipes for further treatment. Because aerobic bacteria is able to more fully treat wastewater, aerobic septic systems typically require smaller drain fields than anaerobic septic systems. Aerobic systems are therefore a space-saving choice, and may be the best options for homeowners who have little space or soil that is not optimal for drain fields.

fiberglass septic tank

Operating Expense

Aerobic septic systems are more expensive to maintain than anaerobic septic systems. Because aerobic septic systems contain working mechanical parts, such as the aerator, they are more susceptible to mechanical malfunction and typically require more frequent routine maintenance. Aerobic septic systems require electricity to operate, so they also increase the monthly electricity bill.

septic tank
On 11, 1, 2014, posted in: FRP Sewage News by Tags:

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