SEPTIC GUIDES FOR HOMEOWNERS
Conventional vs. Aerobic Septic Systems: What’s the Difference?
Both systems treat wastewater from your home. The biggest difference is where the treatment happens and how oxygen gets there. A conventional tank separates solids before the soil provides further treatment. An aerobic treatment unit adds air to provide more treatment before the liquid leaves the unit. EPA guide to septic system types
How a conventional septic system works
Heavy solids settle as sludge. Grease and other floating materials form scum. Liquid between those layers, called effluent, flows to the drainfield.
Anaerobic microorganisms break down some organic material without using dissolved oxygen. Different microbes break larger molecules into smaller ones that other microbes can use. This process can produce methane and hydrogen sulfide. Solids still build up and need to be pumped out as needed. Septic Gases Guide
At the drainfield, effluent spreads through pipes or chambers and soaks into the soil. Aerobic microbes help break down more waste where oxygen is available, and the soil provides further treatment. EPA guide to how septic systems work
How an aerobic treatment unit works
An aerobic treatment unit, or ATU, uses a powered aerator or air pump to add oxygen. Many units hold back larger solids first, then move wastewater into an aerated chamber. A settling stage separates remaining solids from treated liquid. Layouts vary by model.
Aerobic bacteria use dissolved oxygen to get energy from organic waste. They produce carbon dioxide, water, and new cells. Those cells contribute to the solids that still need to settle out and be removed. A loss of aeration can reduce treatment. A single system can support both kinds of activity in separate chambers. EPA aerobic treatment fact sheet · EPA wastewater treatment basics
How does the water treatment compare?
A conventional tank holds back solids and provides some biological treatment. The effluent still carries dissolved waste and small particles, so the drainfield and soil play an important role.
A properly operating ATU can reduce more organic waste and suspended solids before the effluent leaves the unit. Aeration can also help bacteria convert ammonia to nitrate. This changes the form of nitrogen. Removing nitrogen requires additional treatment. Effluent still needs to go to the dispersal or discharge system approved for the property. EPA aerobic treatment fact sheet · EPA nutrient control manual
Pros and cons for homeowners
Conventional gravity system
Advantages: Simpler design. A fully gravity-fed system can work without a powered aerator or pump.
Trade-offs: Needs suitable soil and enough space. Solids that escape the tank can clog the field.
Routine care: Inspect the tank, check and clean the outlet filter if present, and pump when needed.
Aerobic treatment unit
Advantages: Provides more treatment before effluent leaves the unit. It may fit properties that require additional treatment.
Trade-offs: Uses electricity and has more components to maintain. Power loss or aerator trouble can affect treatment.
Routine care: Check the aerator, alarms, pumps, and filters as applicable. Follow the model’s service schedule and remove solids as needed.
Which system fits depends on the soil, space, and treatment requirements. Both need routine care. Ohio Department of Health maintenance guidance
Have questions about maintaining your system? Call Moore’s Septic Services at 740-415-7760.