Sewage Treatment
Brushy Creek Sewage Treatment Plant

The Brushy Creek Sewage Treatment Plant is used here to describe the typical processes which occur at our Local Sewage Treatment Plants.

All of our plants use a form of the activated sludge treatment method. This is a form of biological treatment and is used to remove organic material and nitrogen from the sewage. Activated sludge treatment, introduced over 80 years ago, is one of the most common sewage treatment processes in use world-wide.

A conventional activated sludge plant layout is shown below but each plant is slightly different. Activated sludge plants can be designed to remove between 60% and 95% of organic matter and suspended solids. They require large amounts of energy to aerate the sewage in the aeration tank.

Click on the various parts of the aerial photograph below to discover what happens at each stage of sewage treatment.
Follow the numbers ...
Sewage is pumped into the station Screens remove rubbish from the sewage Activated sludge treatment is one of the most common processes in the world Pebble beds are used to filter sewage UV light disinfaction is used at the final stage Storm basins are used to store sewage after heavy rain Powerful blowers provide the oxygen needed to break down sewage Various chemicals are added to sewage in the process


How sewage is purified

Sewage, from the area surrounding the plant, is pumped into the Brushy Creek Plant to the screens.

The screens remove a variety of larger objects from the sewage.

From here the sewage flows to one of the activated sludge aeration tanks.

Brushy Creek has nine of these tanks. Large air blowers are housed in the blower buildings. These provide air which bubbles through the aeration tanks.

In these tanks, bacteria are added in the outer ring. The sewage stays in the outer ring for about one day where the bacteria with the aid of oxygen, provided by aeration, break down much of the wastes.

Chemicals are also added which precipitate out most of the phosphorus compounds in the sewage.

The sewage then passes into the inner region of the activated sludge tank. This is the settling tank. Here the bacteria settle to the bottom, from where they are pumped back to the aeration tank to be reused.

Next, the clarified water from the top passes into the pebble beds to be filtered. This removes suspended solids which escape from the biological treatment phase.

Before the sewage is released into the local creek or re-used by various industries in the area it passes through the UV (ultraviolet) treatment plant to be disinfected.

We are converting most of our plants to use UV disinfection and only two plants still use chlorine.

The bacteria in the aeration tank are always growing and reproducing. To keep their numbers in control, some bacteria are removed regularly. These bacteria and other solids which are removed are known as sludge.

The sludge is piped about 8 kilometres to a main sewer from where it flows to the Eastern Treatment Plant at Carrum for further treatment.
 

 
Find out about how sewage is treated at other treatment plants.