Stage 1 - Primary treatment

When wastewater arrives at the plant it goes through the primary treatment process.

This initial treatment stage involves removing all the big stuff including solid particles. It's not a pretty sight.

We've found some weird things at the primary treatment stage, including BMX bikes, toys, false teeth and even money!

Cotton-tips are a common sight and they can really cause problems.

Remember, putting the wrong things down the sink or toilet can block the system and lead to sewage overflows.

Once the wastewater enters the plant, the first step is screening.

This process traps things like vegetable matter, paper, cloth and plastics.

This solid waste is washed and compressed to remove any organic matter.

It's then put into screening bins and sent to landfill.

The amount of wastewater coming into the plant varies through the day. Peak activity is between 8 am - 10 am and between 7 pm - 9 pm.

The equalisation tank is used to temporarily store and manage peaks and troughs of wastewater inflow.

The tank acts like a gateway, ensuring the flow of wastewater into the plant is controlled – or equalised.

The grit removal process removes smaller material such as sand, rocks and food pips.

Grit is removed by a forced vortex, which causes grit and organics to spiral to the bottom of the grit removal chamber.

The grit is then washed and left to drain before we put it into the screening bins.

The next step in primary treatment is flow distribution.

At Penrith there are two parallel treatment systems to provide secondary biological treatment. These are the Biological Reactor Process and the Intermittently Decanted Aerated Lagoon.

We'll find out more about these in the next stage.

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