Learning Centre » Water recycling and sewage » Sewage treatment

Sewage and sewage treatment

We all make sewage, but often give little thought to where it goes, how its treated, or even, how it can be recycled.

Water Reclamation Plants Co-ordinator David Greaves examines a screen at the Black Rock Water Reclamation Plant.

What is sewage?

Sewage isn't just from the toilet. Waste water from your shower, bathtub, washing machine, dishwasher, kitchen sink and toilet is all considered sewage.

A typical 4-person household produces around 400–500 litres of sewage every day.

Liquid waste from business and industry is also part of the sewage stream. Industrial sewage is commonly known as trade waste.

Homes and businesses in Geelong produce around 50 million litres of sewage daily.

Sewage is 99.8% water.

 

Sewage versus stormwater

Stormwater is not sewage.

Stormwater is rainwater that collects on your rooftop and street, and is usually collected in gutters and underground pipes. Stormwater typically travels through creeks and rivers to the sea.

Barwon Water does not treat stormwater. In our region, stormwater is managed by local councils.

 

Greywater and blackwater

Waste water from your laundry and bathroom is often called greywater. Greywater can often by reused immediately, for instance on your garden.

Waste water from your toilet is sometimes called blackwater. Blackwater is not suitable for domestic reuse without a dedicated treatment system.

 

Sewage or sewerage?

Sewerage refers to the network; the sewerage system.

Sewage refers to the actual waste water inside the pipes.

 

 

The sewerage system

The sewerage system consists of the pipes, pumping stations and treatment facilities designed to collect and treat sewage.

Our sewerage system comprises 10 water reclamation plants, over 170 sewage pumping stations, and more than 2200 kilometres of sewage pipes.

 

Water reclamation plants

We own and operate water reclamation plants in:

  • Black Rock (Geelong)
  • Colac
  • Portarlington
  • Anglesea
  • Lorne
  • Aireys Inlet
  • Apollo Bay
  • Bannockburn
  • Winchelsea

Under contract, we also manage the Barwon Prison wastewater treatment plant in Lara.

Work is also underway on the Northern Water Plant, a new water recycling facility in Geelong's northern suburbs.

 

 

Sewage treatment

Our water reclamation plants reclaim water from sewage so it can be recycled or discharged with no negative impact on the environment.

Our plants use a mix of biological, chemical and mechanical processes.

 

Pre-treatment

Pre-treatment involves removing objects such as paper, gravel, plastics, bottles, nappies and most identifiable solids.

 

Biological breakdown

Naturally occurring bacteria and other micro-organisms use the sewage as a food source.

This process reduces the amount of suspended solids and organic material by up to 98%.

Normal by-products are water and carbon dioxide.

 

Nutrient removal

Phosphorus and nitrogen are typically reduced by specialised microbes that break down nitrogen compounds into nitrogen gas and absorb phosphorus in their tissues.

 

Filtration

To further clarify the treated water it may be filtered through a sand bed or through pores in a membrane.

 

Disinfection

Disinfection destroys pathogens (disease-causing organisms) that may be present in the treated water. Our plants use chlorine or ultraviolet light.

 

Recycling or discharge

Treated, disinfected sewage is known as recycled water. Where possible, this recycled water is used for a range of purposes, including irrigation sporting grounds, tree lots and farms.

Excess treated water is discharged to the ocean via a submerged pipeline. (Excess water from the Colac Water Reclamation Plant is discharged to Lake Colac.)

 

More information

 


Page last updated Friday 16 July 2010

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