Aerated Wastewater Treatment Systems and Aerobic Sand Filter Systems

Aerated Wastewater Treatment Systems (AWTS)

An AWTS is a small-scale sewage treatment plant for your property. It provides secondary and advanced treatment of domestic wastewater, making it suitable for irrigation use on your land. Installation and maintenance must be carried out by a suitably licensed person.

How It Works

Wastewater flows through a series of chambers:

  1. Primary chamber – solids settle and form sludge; scum floats to the top.
  2. Aeration chamber – air is added to support bacteria that break down waste.
  3. Clarification chamber – further solids settle out.
  4. Disinfection – treated water is chlorinated.
  5. Disposal – treated wastewater is pumped to the approved land application area within the property.

Aerobic Sand Filter Systems

An Aerobic Sand Filter uses natural processes and sand filtration to treat household wastewater.

How It Works
  1. Wastewater enters a primary sedimentation tank, where solids settle and break down.
  2. Effluent moves into a dosing tank, where it is pumped into a sand filter.
  3. As water passes through layers of sand and crushed rock, it is filtered and treated.
  4. The wastewater collects at the base, is disinfected, and then sent to the approved land application area within the property.

Land Application Areas

Treated wastewater must only be disposed of using the approved method for the system. The land application area must be maintained.
Common methods include:

  • Irrigation
    • Surface irrigation: sprayed above ground
    • Sub-surface irrigation: drippers in shallow trenches
    • Covered surface irrigation: drippers covered with mulch or woodchip
  • Evapotranspiration-Absorption Systems
    • Trenches or beds designed to absorb and evaporate water
    • Elevated sand mounds constructed above ground level

The disposal method depends on several factors outlined during the system design stage.
Council approval is mandatory before making any changes to the approved land application area.

Maintenance Responsibilities

  • Aerated Wastewater Treatment Plant: Servicing every 3 months
  • Sand Filtration systems: Servicing every 12 months

Regular maintenance is essential to ensure your system operates safely and efficiently. Poorly maintained systems can pose health risks and harm the environment.

Key maintenance tips:

  • Avoid overloading the system with too many users
  • Use only septic-safe and non-antibacterial cleaning products
  • Never flush foreign objects (e.g., nappies, sanitary pads)
  • Desludge tanks every 3–5 years using a licensed contractor
  • Keep the land application area mowed and maintained
  • Protect the disposal area from vehicle traffic
  • Keep household plumbing in good condition
  • Prevent odours or health risks

Please contact the manufacturer of your treatment plant for further information

Compliance Standards

Your OSSF must meet:

  1. Plumbing and Drainage Act 2018
  2. Plumbing and Drainage Regulation 2019
  3. AS/NZS 1547: On-site Domestic Wastewater Management
  4. Queensland Plumbing and Wastewater Code

Council ensures OSSFs comply with these standards and do not pose risks to public health or the environment.

 

Back to top