Paxton WWTW
The Paxton plant serves the village of Paxton.
It currently treats 70 kilolitres per day and can handle wastewater from a population equivalent to 1,000 people.
How it works
The Paxton plant provides secondary treatment of the wastewater using the activated sludge process. Effluent polishing and disinfection are achieved using a maturation pond and artificial wetlands. As illustrated in the process flow diagram, the plant consists of:
- An intermittent decant extended aeration (IDEA) activated sludge tank
- A catch pond
- A maturation pond
- A set of constructed wetlands (two trains of three cells in parallel)
- Two sludge lagoons
- An effluent irrigated tree plantation (EITP).
How is the treated effluent used?
As a result of large storage capacity in the maturation pond, up to 150 kL/d of recycled water from the plant is used to irrigate the onsite plantation during summer days. As effluent is used for irrigation, demands tend to be much lower during winter due to increased rainfall.
Unused treated effluent is discharged to Congewai Creek via artificial wetlands.
The sludge lagoons are typically dewatered every four years and the biosolids produced are beneficially used for mine site rehabilitation or agricultural pasture improvement.