Sewage treatment

The Warrnambool Sewage Treatment Plant is located north-west of Thunder Point. It’s the largest of our sewerage systems, covering Warrnambool, Koroit and Allansford. The plant services a total population of around 35,000.

Sewage reaches the plant via a Sewage reaches the plant via a 300-kilometre-long network of sewer pipes and 42 pumping stations. The system has special facilities for brine disposal, a salty waste from industries. It also accepts septic tank waste from contractors.

Once it reaches the plant, we screen out any larger items, rubbish and grit and send it to landfill.

The sewage is then treated in large tanks where naturally-grown bacteria and micro-organisms use it as a food source. They break down any organic material and reduce the physical, chemical and biological contaminants. This process uses cycles of aeration to treat the sewage before it settles.

We decant this treated water from the surface of the tank. It travels through a tertiary screening system and then into the ocean mixing zone.

Sludge is taken from the bottom of the tank and excess water removed. The dried sludge is then transported offsite and stabilised in drying beds for several years. It can then be re-used on farms as a soil conditioner, known as biosolids.

Domestic sewage runs through a network of sewer pipes and 17 pumping stations to reach the Port Fairy Sewage Treatment Plant.

The plant also has separate tanks and infrastructure to treat the industrial waste that comes from SunPharma.

Once it reaches the plant, we screen out any larger items, rubbish and grit and send it to landfill.

The sewage is then treated in large tanks where naturally-grown bacteria and micro-organisms use it as a food source. They break down any organic material and reduce the physical, chemical and biological contaminants. This process uses cycles of aeration to treat the sewage before it settles.

We decant the treated water from the surface of the tank. It then travels through an ultraviolet disinfection process. This helps to get rid of harmful bacteria. The water is released to a mixing zone off the south side of Griffiths Island.

Sludge is taken from the bottom of the tank and excess water removed. The dried sludge is then transported offsite and stabilised in drying beds for several years. It can then be re-used on farms as a soil conditioner, known as biosolids.

The Portland Sewage Treatment Plant is located just off Oleria Road, south of the city.

Sewage and trade waste runs through a network of sewer pipes and is collected at three major pumping stations in the city. It’s then pumped under pressure to the treatment plant.

Once it reaches the plant, we screen out any larger items, rubbish and grit and send it to landfill.

The sewage is then treated in large tanks where naturally-grown bacteria and micro-organisms use it as a food source. They break down any organic material and reduce the physical, chemical and biological contaminants. This process uses cycles of aeration to treat the sewage before it settles.

We decant the treated water from the surface of the tank. It then travels through an ultraviolet disinfection process. This helps to get rid of harmful bacteria. The water is released to an ocean mixing zone at the base of steep cliffs to the south of the plant.

Sludge is taken from the bottom of the tank and excess water removed. The dried sludge is then transported offsite and stabilised in drying beds for several years. It can then be re-used on farms as a soil conditioner, known as biosolids.

Lagoon-based sewage treatment plants service Camperdown, Casterton, Cobden, Coleraine, Dunkeld, Hamilton, Heywood, Mortlake, Peterborough, Port Campbell, Simpson, Terang and Timboon.

A biological process reduces the amount of organics and harmful products in the sewage over a set holding time. We monitor the levels of these nutrients and abide by strict limits set by the EPA during this period. We can then recycle, irrigate or discharge the treated water as required.

At Hamilton and Camperdown, we use a biofiltration treatment process. The process begins with the removal of grit and sand followed by the screening of any coarse items and rubbish which is disposed of.

Sewage is then fed into a clarifier, where solids fall to the bottom, forming sludge. The sludge is removed and dried for a number of years to become biosolids. It’s then reused as a soil conditioner on local farms.

We pump the remaining liquid sewage through coarse rock trickling filters. This is a natural process where bacteria on the rock bed consumes the organic pollutants and purifies the water stream.

The sewage is then held in a primary lagoon. Here, aerobic micro-organisms consume any remaining organic matter. This neutralises pollutants and helps the treatment process.

After aeration, the water flows to a maturation lagoon to settle where sunlight (UV rays) kill pathogens over time. The recycled water is then used to irrigate nearby sporting facilities and farms.

All our other inland sewerage systems use lagoon-based treatment. Sewage flows to a primary lagoon where aerobic bacteria consume any remaining organic matter. This neutralises pollutants and helps the treatment process.

After this primary treatment, the water flows to a maturation lagoon to settle where sunlight (UV rays) kills harmful bacteria over time.

The winter storage lagoon holds the final water before it is used for irrigation on nearby farmland over the summer period. It’s also used to irrigate nearby sporting facilities and farms under agreement with the EPA.

All lagoons are lined with compacted clay that is typically 600 to 800 millimetres thick. This acts as a barrier, preventing sewage and treated water leaching onto the surrounding land or into the groundwater table.

We routinely sample the water before irrigation. We also regularly inspect all our lagoon-based facilities to ensure they are structurally sound.

We also have several bores across each site. They monitor water quality of the shallow groundwater to ensure there is no impact on the environment.