In unsewered areas, the proper treatment and utilisation of household wastewater on-site is critical in preserving the health of the public and the environment. Aerated Wastewater Treatment systems (AWTS) have been developed as a way of achieving this.

AWTS is a purpose built system used for the treatment of sewage and liquid wastes from a single household or multiple dwellings An AWTS will treat all grey and Blackwater from the household. Once entering the system the waste is broken down in the primary chambers through the presence of anaerobic micro-organisms, once the wastewater leaves the primary chambers it enters the Aeration chambers, this is where aerobic treatment is used to breakdown the wastewater further. Oxygen is pumped into these chambers via defuses to produce an aerobic state, which clean the water as it passes through. After the wastewater leaves the aeration chambers it enters the Settling chamber, in this chamber the suspended solids are allowed to settle under still conditions, the settled particles referred as sludge is returned to the primary chamber for further treatment. The now almost clear water is passed through the disinfection chamber where a regulated chlorination retention chamber will remove the final bacteria before flowing into the pump chamber. Once entering the pump chamber the wastewater is fully treated and will automatically pump out to irrigation, when the pump float operates.

Selecting a System

When looking for an Aerated wastewater treatment system for a new property or a replacement of an existing system, you need to consider a few things. Property size, blocks of land less than 2000 square metres are deemed to be too small for wastewater treatment systems as the available land area is not large enough for the irrigation disposal area.  In these cases a different type of system may be required such as a Septic Pump out system. Another thing to consider is how many people will use the system, all standard domestic wastewater treatment systems are licenced to treat up to 10 people. Larger systems are available to treat more people as required.

When sizing a wastewater treatment system for a customer, we ask how many people will use the system regularly and how many bedrooms are in the home, is the home on town water supply or tank water, what council area, and the land or block size. From this information Civcon can normally give an estimate of cost of a system, from this stage normally we will then arrange a site visit to discuss with the client the options as to the location of the system and the irrigation disposal area. Buffer distances need to be taken into consideration also such as distances from Dams, Waterways, and Boundary’s. Local council areas have different regulations regarding the Irrigation disposal areas, some councils allow spray or surface irrigation, but most these days are requiring subsurface irrigation to be installed.  Some councils require a geotechnical report to be carried out on the property to determine the soil quality; this will then determine the size of the application area, and any soil improvement conditions required.

It is regarded these days that the Irrigation disposal is as important as the wastewater treatment system its self, due to public health issues. This is why most councils these days prefer to use subsurface irrigation, due to the limited contact that can occur.

Regulations and approvals

Local governing authorities (Councils) are primarily responsible for approving an AWTS in their area and dictate standards for installation, servicing and maintenance of these systems. Civcon provide, complete and submit all the required application forms on your behalf to speed up the approval process.

• Requirements for servicing Aerated Wastewater systems.