Some commercial land pockets near Perth Airport are not connected to sewer, and rely on on-site treatment plants. The waste stream from several buildings is pumped to a central treatment system, which is sized on the anticipated daily volumes from the employees and visitors for those buildings.
So far, three onsite plants have been built, and they range from 4 kL to 21 kL treatment per day. The Graf Klaro Treatment Plant is a multi-tanked aerated system which changes raw effluent into secondary standard wastewater. The treated effluent is sent to either leach drains or is further filtered and treated for irrigation of lawn and gardens.
An air compressor (blower) provides air to operate lift pumps to transfer effluent from one tank or stage to the next, as well as to oxygenate the treatment tanks to encourage aerobic bacteria to thrive. Servicing is carried out every three months and reports sent to the clients. Pumped effluent was tested for pH, Dissolved Oxygen, Turbidity and Residual Chlorine.
The following photographs and comments show some aspects of the installation of the larger systems.
These projects showcase best practice in water conservation and recycling. The larger 20 kL systems conservatively treat five million litres of water each year, all of which is used to either recharge the soil or to water plants for landscaping amenity.