Sacyr’s organics recycling plant: south-east Melbourne

Sacyr Environment Australia is building a new organics plant to divert waste from Melbourne landfills.

As Victoria’s population continues its growth spurt, so too does the amount of waste generated, with Sustainability Victoria (SV) estimating 20 million tonnes of material will enter the state’s waste and resource recovery system by 2046.

SV’s 2018 Statewide Waste and Resource Recovery Infrastructure Plan says that additional capacity will be required just to maintain current rates of resource recovery and will need significant investment into new infrastructure.

The plan also states the closure of landfills in Clayton South and the Mornington Peninsula will also see an increase in landfilling activities over the next five years, putting pressure on other landfills in the city’s south east to provide airspace and service the region over the medium term.

Victorian Environment Minister Lily D’Ambrosio writes in the plan that increasing the recovery of organic materials, particularly food waste, will be critical to reducing the amount of waste sent to landfill.

“The system currently manages nearly a million tonnes of food waste, but in 2015–16 only 10 per cent was recovered. Victoria will need new collection services and processing facilities to recover valuable nutrients and energy,” she writes.

To fill this niche in the market, international waste management company Sacyr Services, through its Australian branch Sacyr Environment Australia, has begun construction on a $65 million South Eastern Organics Processing Facility in the Melbourne suburb of Dandenong South.

The facility is planned to begin operations in 2019 and will service the Bayside, Cardinia, Casey, Frankston, Glen Eira, Greater Dandenong, Kingston and Monash councils.

It aims to have an annual processing capacity of 120,000 tonnes of waste per year, the equivalent of 12,000 truckloads, and create 50,000 tonnes of high grade compost annually. The compost will then be sold to local councils at a predetermined price and to private consumers at a market price.

Carlos Gros Isla, Director of Sacyr Environment Australia, says the company is taking its 20 years of expertise in the European market to Melbourne’s suburbs.

“This type of facility has been used in Europe for many years, but in Australia it is still quite new,” he says.

He says what sets the facility apart from the rest of the market is its specific location.

“If you can place a facility whereever you wanted on a map, the closer it is to the population the better. This means it will have reduced transport costs and be closer to the source of the waste,” Carlos says.

“The downside to this is the fact that composting can produce strong odours. For that reason, many composting facilities are far away from residential areas.

“To ensure we are able to remain close to the councils in the south east, we have invested in very stringent odour control systems,” he explains.

Carlos says Sacyr uses a conceptually simple design with advanced technology to reduce odours.

“We capture the air within the building and pass it through an acid scrubber to neutralise the basic chemicals. We then include a chiller that keeps the acid scrubber operating at its peak without any influence from temperature during summer or winter,” he says.

“Our system allows the facility to treat the dirty air by adapting the recirculation of the air inside the building to the weather conditions such as wind speed and direction. 

“This allows us to clean the air fewer times per day in volume when the conditions are not favourable,” Carlos adds.

Carlos says there is an urgent need to have the facility open as soon as possible to provide relief to nearby landfills and allow the local councils to begin rolling out food organics and garden organics programs.

INDUSTRY EXPERTISE

One technique that separates this processing facility apart from others in Australia is the fact that most contaminants are removed at the end of the composting process, Carlos explains.

“We believe we can remove contamination best when the compost is drier and spongey. The density is higher, making it easier to remove the contamination,” he says.

The process begins at the pre–treatment area with a drum screen that separates the waste by size, with anything that is too large shredded. Carlos says an object would have to be harder than a fridge to do damage to the shredder, meaning that any metals in the feedstock are broken down to an easier size to extract.

“After the shredder, both streams go back together and are sent to a mixer. Any metals at this stage are separated with a ferromagnet and an eddy current to remove any iron or aluminium.”

The organics are then sent to the composting area of the building which is separated from the pre–treatment area by walls then loaded into the composting tunnels. Carlos says Sacyr uses the tunnels to provide better control over the composting process by recirculating the air and leachate.

“We monitor moisture, oxygen and temperature, and with these parameters we’re able to use our industry experience to follow the right mixture to provide the best quality compost possible,” he says.

Carlos estimates the organics will be in the tunnels for 14 days before being moved to the maturation process.

“We do the maturation in windrows and mature the compost for 28 days, following EPA guidelines and directions, even though we strongly believe we could achieve the Australian standard quality in 21 days,” Carlos says.

“When the compost has matured, we refine it and separate any contaminants with a drum screen and a densimetric separator, which takes out any plastics, glass, textiles and other contaminants.” 

Carlos says Sacyr is interested in showing the Australian market what it can do with this project and how it will perform.

“We are willing to have the facility operational and showcase how the technology can perform. At this stage, we want to show everybody what we can do with our experience in the industry and hope to have other businesses and designs like this in Australia.”