The wastewater treatment process involves screening debris, grit removal through aeration and settling, organic reduction through aerated lagoons, phosphorus removal by adding alum, UV disinfection to kill bacteria, sludge digestion to produce a stable sludge, and final dispersal through an outfall structure and wetland pond into a river.

1. Outline of Wastewater Treatment

3. 1 Screening Three course screens collect debris such as rags, plastics and larger solids. The screenings got to the landfill.

4. 2 Pre-aeration & grit removal Air is pumped into the pre-aeration tank where grit falls out of suspension into a collection hopper.

5. 3 Sedimentation Three 40 metre long sedimentation tanks allow heavy solids to settle to the bottom and fats, oils and greases to rise to the top. About 60% of solid matter is removed at this point.

6. 4 Aerated lagoons Air is pumped into the lagoons by large paddle aerators to provide oxygen to help microbiological organisms grow and consume the organic material as a food supply

7. 5 Phosphorus removal A new facility to reduce the phosphorus in the wastewater. Alum will be added so that dissolved phosphorus settles out as sludge.

8. 6 UV disinfection Banks of ultra violet lamps mounted in the wastewater channel emit light of a wavelength that kills 99.9% of bacteria as the wastewater flows past.

9. 8 Outfall structure This distributes the discharge along 50m of rock embankment providing better mixing and a more aesthetic interface with the river. 7 Wetland pond and land passage This facility allows the flow to pass through a wetland pond and a rock land passage before entering the river. It also provides addition storage for wastewater at high river levels and some extra treatment.

10. 9 Sludge digesters Sludge is held in digesters for 20 days at 35°C. Anaerobic breakdown occurs producing a more stable and more easily dewatered sludge.