Digging Deeper into Council-Created Compost

Our recent story on Terri-Anne and Mark Lewis – the Cathcart couple whose homegrown market garden is finding its feet with the help of 200 tonnes of Council-created compost – received a lot of interest from the community.

Council are pleased to share more information into how the high quality compost is created right here in Ararat.

The compost project is a joint venture between Ararat Rural City Council and Gaia EnviroTech, a bioenergy and waste management company based in Ballarat. Gaia have set up their composting system at Ararat’s Transfer Station, but it isn’t all about immediate results. It’s a reciprocal partnership, which has allowed Gaia’s senior engineers to try out new ideas within the composting process with some exceptional results.

“We need to be collaborative, and commit to the process of research and development,” Ararat Rural City Council CEO Dr Tim Harrison explains of the partnership. “We’re not just end recipients; this isn’t a turn-key solution. It’s about continual innovation – and there are a whole range of great community stories coming out of it.”

One of those stories is the Lewis’s fledgling market garden.

Here’s how the ingenious set-up at Ararat Transfer Station produces 120 tonnes of composting material per fortnight.

The compost’s journey begins with the mixing of green waste and food waste, all collected from across our community by Council’s dedicated waste truck drivers. It’s a ratio which, Gaia’s Technical Director Sandy Gray says, has been carefully weighed to result in a first-class end product.

Contaminants are removed from this enormous mix by hand, after which the material is shredded by machine, and loaded into one of four pasteurisation containers. These vessels are repurposed shipping containers, modified by Gaia following the company’s own innovative design. 

Then begins the pasteurisation ‘cook’, a process which sees the mix heated to the point of maintaining a temperature of over 55 degrees across 72 hours. During pasteurisation, engineers can check and control temperature, moisture and many other factors completely digitally – even remotely, from their offices in Ballarat. The readings are collected from several spec-built probes which pierce the sides of each compost container at specific points, and the info is accessed through bespoke data analytics software, called Neon.

The maturing compost’s liquid is drained and captured in a small external tank, then sprayed back into the mix via the container’s overhead sprinklers (according to the material’s hydration requirements).

Once pasteurisation is complete and all pathogens destroyed, the material is sent through a fine screen. This ensures consistency of the final product’s granularity, though at this stage the compost is already very fine; only 10-20% of material is screened out during this step, Senior Engineer Georges Delemontex tells us.

The last step for the compost is to be tested, to ensure it complies with a list of regulations and guidelines for health and safety. Dr Harrison says these standards are strictly adhered to. “Every batch of compost we process is sampled and sent to the Gaia EnviroTech lab for testing,” he explains. “Our aim is to produce a very high quality product which will best serve our local community’s projects.”

If you’re interested in knowing more about how to get a 50+ tonne batch of Council-created compost for your agricultural project, or about the exciting partnership between Ararat Rural City Council and Gaia EnviroTech, contact Ian Cooper at [email protected].