On-site wastewater treatment systems
Primary treatment systems
Health
caution: Primary treatment systems do not kill pathogenic bacteria, viruses or parasites. Effluent must be handled with extreme caution, and contact with people, food, clothing and pets must be prevented. Wash your hands and clothes if contact occurs.
Septic tanks
Septic tanks separate solids from liquid wastewater, and provide a living ecosystem where bacteria and biological processes digest the waste.
When wastewater passes through a septic tank it forms three layers:
- a layer of oil and fats (called scum) which floats to the surface and forms a crust
- a layer of solids (called sludge) which settles to the bottom
- a clear layer in the middle (called effluent) which flows out to the land disposal area.
Fats and solids are retained in the tank and break down over time. The scum layer helps prevent odours escaping and stops air from entering. As wastewater enters the septic tank, effluent flows out to a land application system (e.g. a subsurface soakage trench).
Alternative biological systems (e.g., worm farms)
Alternative biological systems achieve primary treatment using filtration, microorganisms, worms, and invertebrates to digest sewage and kitchen waste. The resulting effluent is disposed of to a subsurface land application system (e.g., a soakage trench).
Secondary treatment systems
Health caution: Secondary treatment systems do not kill 100% of pathogenic bacteria, viruses or parasites. Treated wastewater must be handled with extreme caution, and contact with people, food, clothing and pets must be prevented. Wash your hands and clothes if contact occurs.
Aerated wastewater treatment systems (AWTS)
AWTS use aeration and clarification processes to biologically treat wastewater. Following disinfection, the treated wastewater is typically irrigated to a dedicated irrigation area. Alternatively, undisinfected wastewater is disposed of to a subsurface land application system (e.g., a soakage trench).
Passive secondary treatment system
A passive secondary treatment system biologically treats wastewater without the use of mechanical parts. Following disinfection, the treated wastewater is typically irrigated to a dedicated irrigation area. Alternatively, undisinfected wastewater is disposed of to a subsurface land application system (e.g., a soakage trench).
Greywater treatment systems
Greywater treatment systems treat greywater (wastewater from baths, showers, basins, laundries and kitchen sinks) using biological processes. Following disinfection, the treated greywater is typically irrigated to a dedicated irrigation area. Blackwater (wastewater from toilets and urinals) is required to be managed by a separate wastewater system.
Blackwater treatment systems
Waterless composting toilets
Waterless composting toilets receive wastewater from toilets only. With the help of a continuous flow of air, wastewater is treated through biological and evaporation processes. Decomposition of wastewater over time results in the creation of compost, which is removed and buried. Excess liquid is typically directed to a subsurface land application system (e.g., a soakage trench).
Incinerating toilets
Incinerating toilets incinerate wastewater, resulting in the creation of an ash product that is required to be buried. They are not connected to plumbing. Greywater (wastewater from baths, showers, basins, laundries and kitchen sinks) is required to be managed separately.