These systems are commonly found in rural areas where public sewers are not available, and may be used for a single residence or for a small group of homes.
The disinfectant typically used is tablets of calcium hypochlorite, which are specially made for waste treatment systems.
Stabilized forms of chlorine persist after the effluent is dispersed, and can kill plants in the leach field.
The pre-treatment and effluent handling are similar for both types of systems, and the difference lies in the aeration stage.
[1] CFSGAS systems, as the name implies, are designed to handle continuous flow, and do not provide a bed for a bacterial film, relying rather on bacteria suspended in the wastewater.
A medium to promote fixed film bacterial growth may be added to some systems designed to handle higher than normal levels of biomass in the wastewater.
Further, effluent with high dissolved oxygen and aerobic bacteria flow to the distribution component and digest the bio-mat.
Within the chamber, the urine and feces are independently broken down not only by aerobic bacteria, but also by fungi, arthropods, and earthworms.
A typical ATS will, when operating correctly, produce an effluent with less than 30 mg/liter BOD5, 25 mg/L TSS, and 10,000 cfu/mL fecal coliform bacteria.