Wastewater Treatment

Outline of Wastewater Treatment

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

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

3 SedimentationThree 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.

4 Aerated lagoonsAir 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

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

6 UV disinfectionBanks 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.

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.

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.