What are biosolids?
Biosolids are nutrient-rich organic materials that look, smell and feel like dark, rich organic soil. They’re produced as a by-product of the sewage treatment process.
How are biosolids produced?
During the treatment process, naturally occurring bacteria and micro-organisms consume the sewage. They break down the original organic solids and help remove pathogens (bacteria).
Treated effluent is then decanted and discharged to the ocean or dams. We remove the remaining material, known as sludge, from the bottom of the tank and siphon any excess water.
The sludge comprises dead micro-organisms and a small number of active micro-organisms. It also contains inert solids, such as sand, which have come down the sewer.
We transport the sludge to our specialised facilities where it’s dried and composted. This takes a few years and satisfies Environment Protection Authority guidelines. It’s then known as biosolids, a product ready for beneficial reuse as soil conditioner. The material is mainly spread on broad-acre agriculture, pasture and cropping properties.
Does it smell?
Most biosolids have a slightly musty, ammonia odour although some biosolids have a stronger odour, particularly when they are being moved and processed into wind rows. This isn’t harmful to health but may impact people in the nearby area, particularly those who are more sensitive to smells. We carefully monitor any potential odours and adjust our operations to suit wind conditions.
We also have on-site misters that spray natural deodoriser during the sludge movement processes at our Hamilton and Camperdown storage facilities to help neutralise any odours. The mist is a natural blend of essential oils, food grade surfactants and purified water.
A dedicated team meets weekly during the processing season, and more regularly when required, to address any complaints and work through issues..
Where are the biosolid facilities located?
We operate two major sites to process sludge into biosolids – one at Camperdown and the other in Hamilton. We also have a smaller site at Portland.
Looking to the future
As our region continues to grow, so does the amount of domestic and industrial waste we need to manage. To plan ahead, we’re exploring long‑term options for handling biosolids in a safe, reliable and sustainable way.
That’s why we’re investigating a new regional biosolids processing facility. But finding the right site and getting approvals will take time. It’s an important project, and we want to get it right.
What’s the process?
Frequently asked questions
Find the answers to the most commonly asked questions.
Sludge produced from our sewage treatment plants at Warrnambool, Portland and Port Fairy is transported to our purpose-built biosolids facilities to be processed. These are located at Camperdown, Hamilton and Portland and operate under an EPA licence
The sludge material processed at our biosolids facility is not “raw sewage”, “human sewage”, “human waste” or “human poo”. It is the sludge material removed at the end of an extensive sewage treatment process.
The sewage that enters the sewerage system is anything from household bathrooms, toilets, kitchens, laundries and drains. It also includes waste from our regional industrial customers. It’s around 99.6 per cent water; the remainder is mostly biodegradable pollutants and small solid particles.
Most biosolids have a slightly musty, ammonia odour although some have a stronger odour. This often happens when the sludge is being moved and processed into wind rows to increase drying times during the warmer months. This isn’t harmful to health but may impact people in the nearby area, particularly those who are more sensitive to smells. Warm weather and strong winds can also increase the intensity and spread of odour to nearby residences.
To reduce odours as much as possible in the short term, we:
- Adjust our operations based on wind and weather conditions.
- Use a misting system that sprays a natural deodoriser during deliveries and processing.
- Pause processing during long weekends and major local events.
We’re also trialling a soil capping to help limit odour emissions.
We’re nearing commissioning of the Warrnambool Sewage Treatment Plant upgrade – this provides a medium term solution. Once operational, this will significantly improve our ability to manage the growing volumes of domestic and industrial waste from across our region.
Over time, this will improve the quality of material processed at all our biosolids facilities and contribute to a reduced odour impact
We’ve completed detailed work looking at long term regional biosolids management options.
Our preferred solution is a new regional biosolids processing facility, designed to significantly reduce impacts on communities near existing sites. Finding the right location, completing planning and approvals, and building a new facility will take time, but this work is underway.
We can temporarily pause processing at one site, but without an alternative in place this would create safety, environmental and service risks elsewhere in the system. Simply shifting the problem from one community to another isn’t a solution.
We’ve proactively informed the EPA of odour complaints at all our sites over the past 12 months. The EPA has visited our facilities, reviewed our operations, and advised they are satisfied that we are operating within regulatory requirements.
They have not identified additional short-term measures that would materially improve outcomes beyond those already underway. We will continue to report to and engage with the EPA as required.
The management of biosolids is a complex challenge for all water authorities, not just Wannon Water. This is being driven by growing industrial and domestic waste streams, increasing regulatory scrutiny, and public perception issues.
We don’t offer compensation for odour impacts as part of our business operations. People experience and perceive odours differently, making it difficult to assess the level and timing of their impact in individual cases.
If you notice an odour problem, you can contact us to lodge an issue or complaint. Simply call 1300 926 666 or email info@wannonwater.com.au.
You can also report odour concerns to the EPA by calling their 24 hour hotline on 1300 372 842.
