Grit
Small insoluble particles in wastewater such as sand, coffee grounds gravel, glass and food particles.
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Recycling water
Wollongong Water Recycling Plant is one of 30 water recycling treatment and wastewater treatment plants in Greater Sydney, the Blue Mountains and the Illawarra. It serves Wollongong and surrounding suburbs.
Facts and figures
Location: Port Kembla Road, Wollongong.
Population served: 200,000 people.
Area served: 71 km2, including Port Kembla, Bellambi, Wollongong and surrounding suburbs.
Amount of wastewater treated: 49.8 million litres each day.
Treatment level: Tertiary.
Recycled water applications:
- We re-use some water on-site for industrial purposes like washing down equipment and filter backwashes.
- Wollongong City Council uses our recycled water to water grass and gardens at local sports fields.
- Wollongong Golf Club uses our recycled water to water the greens.
- Port Kembla Coal Terminal uses our recycled water for dust suppression.
- BlueScope Steel uses our recycled water for steel manufacturing.
Environmental discharge: We release any remaining recycled water to the ocean, about 1 kilometre offshore.
Amount of biosolids produced: 11,000 tonnes each year.
Operating licence and regulation: We operate the plant under 3 sets of rules:
- Environmental protection licence issued by NSW Environmental Protection Authority (EPA). View the licence limits.
- Recycled water produced by the plant must meet the Australian guidelines for water recycling.
- Biosolids produced by the plant must meet the EPA's biosolids Environmental guidelines: Use and disposal of biosolids products.
Technical resources
Wollongong Water Recycling Plant technical data (332KB) – read technical specifications for the plant.
What's in wastewater? (279KB) – learn about common wastewater parameters.
Removing nutrients in wastewater (192KB) – fact sheet.
Flow chart
Primary treatment
Primary wastewater treatment removes large solids using physical separation processes.
Screening
Screens trap and remove large solids as wastewater flows through
Grit removal
We inject air into a tank, causing the water to spiral. The air flings the grit, such as sand and coffee grounds, to the edges. It collects in the bottom of the tank where a scraper removes it.
The grit and screenings captured are sent to landfill.
Large solids like wipes, food scraps, rubbish, cotton tips and plastic are caught on the screens.
Sedimentation
Wollongong uses 2 different types of sedimentation processes.
Traditional sedimentation allows solids to settle to the bottom of the tank while oil and grease float to the top. Scrapers at both the bottom and the top of the tanks remove the solids, oil and grease, which are treated to produce biosolids.
A multi-flow tank (sometimes called a 'lamella plate') uses a set of stacked inclined plates. Water travels up and over the inclined plate, but solids are too heavy and are captured on the plate. Mechanical scrapers remove the solids, which are treated to produce biosolids.
In a traditional sedimentation tank, we use scrapers on top to remove floating scum and settled solids.
Secondary treatment
Secondary treatment removes phosphates and nitrates using physical, biological and chemical processes. Learn more about Removing nutrients in wastewater (192 KB).
Wollongong uses 2 types of secondary processes that work in a similar way:
- a Conventional Activated Sludge system (CONVAS)
- a bioreactor.
CONVAS and bioreactor
We add a high concentration of microorganisms (activated sludge) to the wastewater. In the CONVAS we use large mechanical aerators to introduce air into zones of the tank. In the bioreacter we introduce the air using small diffusers at the bottom of the tank. By varying the amount of air in different parts of the tank, we ensure different types of micro-organisms are able to break down nutrients (like nitrogen and phosphorus).
The bioreactor uses diffuser aerators.
Secondary clarifiers
The activated sludge settles to the bottom of the clarifier where scrapers remove it. We recycle some of this sludge back into the bioreactor and treat the rest to produce biosolids.
The treated water from the top of the tank flows to tertiary treatment.
We use clarifiers to separate the activated sludge from the treated wastewater.
Tertiary treatment
Tertiary treatment uses chemical and physical processes to remove very fine solids and disinfect the treated wastewater.
Filtration
Filters made of layers of sand and coal trap remove any remaining fine particles.
Disinfection
Wollongong uses 2 types of disinfection:
- ultraviolet light
- chlorine.
For recycled water that will be used on site, at the golf course, sports fields and coal terminal, we use both ultraviolet light and chlorine to kill any micro-organisms that can make us sick.
For recycled water that will be discharged to the ocean, we use ultraviolet light only.
Filters made of layers of sand and crushed coal trap very fine solids.
Advanced water recycling
Advanced water recycling uses membranes to remove extremely fine particles, including dissolved salts, from the water.
Microfiltration
We pass the water through a hollow fibre membrane that has a pore a size of 0.05–2.0 micron (µm). Particles larger than the pore size are trapped on the membrane and the water passes through.
Reverse osmosis
We push the water through a flat sheet, spiral-wound membrane known as a reverse osmosis membrane. The membrane pore size is 0.0005 micron (µm). The pore size is so small that it can remove nutrients, chemicals, bacteria, viruses and dissolved salts from the water.
This very high-quality water is used by BlueScope Steel.
A microfiltration membrane.
Re-using the water
On our plants, we use recycled water instead of drinking water wherever we can. Hoses, sprays and filter backwashes all use recycled water. We use the remaining recycled water for a number of different things.
Local sports fields
Wollongong City Council uses recycled water to irrigate JJ Kelly Park soccer fields and Vikings Rugby field.
The sports fields are within one kilometre of the Wollongong Water Recycling Plant. We pump recycled water to the council's 120,000 litre storage tank, which is used to irrigate 22 hectares of sports fields.
The council uses about 5 million litres of recycled water each year. The council generally irrigates the sports fields at night to help reduce water loss from evaporation.
Local golf course
We supply Wollongong Golf Club with as much recycled water as they need to irrigate the greens and fairways.
The golf club is next door to the Wollongong Water Recycling Plant. We pump recycled water to the club's 2.8 million litre storage dam, which is used to irrigate 25 hectares of the 45-hectare site.
It uses about 50 million litres of recycled water each year. The amount of recycled water used varies, depending on the weather and other factors.
The club generally irrigates the course at night to help reduce water loss from evaporation.
Dust suppression
Port Kembla Coal Terminal uses recycled water for dust suppression. They spray recycled water on the coal to keep it damp and reduce dust as it's moved around. They've been using recycled water since 2008.
Steel manufacturing
BlueScope Steel uses high quality recycled water for steel manufacturing. 99% of the water they use comes from either recycled water or salt water. They use recycled water for cooling, dust suppression, descaling and scrubbing. Learn more about BlueScope's environmental improvement initiatives.
Wollongong Golf Club uses recycled water to irrigate.
Port Kembla Coal Terminal uses recycled water for dust suppression.
BlueScope Steel uses recycled water for cooling steel.
Operations and maintenance
Running the plant
Eight staff manage, operate and maintain the plant. They collect and analyse water samples, do laboratory testing and manage special projects to keep the plant running safely and efficiently.
Maintaining the plant
There are 3 types of maintenance required to keep the plant operating: preventative, planned and reactive.
See the table to below for examples.
A small team make sure the plant runs efficiently.
Maintenance type |
Description |
Example |
|---|---|---|
Preventative |
Prevents a break down |
Oiling a motor |
Planned |
Replacing equipment as it reaches the end of its useful life, before a break down |
Replacing a worn motor |
Reactive |
Fixing equipment that has unexpectedly broken down |
Repairing a motor |
Come behind the scenes
Want to visit one of our sites? We offer free excursions and technical tours to schools, universities and community groups.