Sydney trials kerbside food waste collection

A City of Sydney waste trial will see food scraps from up to 4000 homes diverted from landfill, and used to create green energy and plant fertiliser.

The trial involves separate collection and recycling of food scraps from residential properties in the council area.

Participating households have received a small kitchen caddy to store food scraps, an initial supply of compostable caddy liners and a food scraps bin to be placed on the kerb for pick up.

Lord Mayor Clover Moore said the trial was an important step in the evolution of waste collection, and a critical component of the city’s waste strategy and action plan, endorsed by council in 2017.

“There have been many advancements in waste separation technology, but the most effective method is when our residents separate the waste themselves at the source,” Ms Moore said.

“Food scraps generally make up one-third of the average red lid bin, so this trial will divert a significant amount of waste from landfill.”

The collected waste will be sent to EarthPower, Australia’s first food waste-to-energy processing facility.

“The scraps will be processed using anaerobic digestion technology, where microorganisms break down biodegradable material in a chamber without oxygen,” Ms Moore said.

“This process produces biogas, which is converted to green electricity and a nutrient-rich sludge that is dried and granulated to produce nutrient rich fertiliser.”

330 houses and 53 inner-city apartment blocks have been selected to take part in the trial.

“If successful, we’ll look at providing this service across the entire council area,” Ms Moore said.

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Geopolymer concrete laid in Sydney

Geopolymer concrete, made with industrial waste from coal-fired power stations and steel manufacturing, is being used for a green roads trial in the City of Sydney.

New concrete has been laid on a busy inner-city street, replacing a 30 metre section of roadway on Wyndham Street in Alexandria.

To test the concrete’s durability, the city has laid 15 metres of traditional concrete and 15 metres of the geopolymer concrete.

Nine sensors have been positioned to monitor and compare how the geopolymer concrete performs.

Sydney Lord Mayor Clover Moore said UNSW Sydney researchers and the CRC for Low Carbon Living will use trial results to create the first set of industry guidelines for geopolymer concrete.

“Local governments are responsible for maintaining local roads, so if we can purchase more environmentally sustainable materials, we can fight climate change and provide quality infrastructure for our community,” Ms Moore said.

“With 70 per cent of the concrete produced today going into pavements and footpaths, there’s great potential to further lower emissions from our operations.”

Made from fly ash and blast furnace slag, geopolymer generates 300 kilograms of CO2 per tonne of cement, compared to the 900 kilograms from traditional cement production.

“We’re continually working with concrete suppliers to reduce the amount of pollution and greenhouse gases emitted during the production of concrete for our local roads,” Ms Moore said.

“We already use sustainable green concrete for all our footway renewal works – which adds up to 25,000 metres squared per year.”

According to Ms Moore, the low CO2 concrete has the potential to reuse 400 million cubic tonnes of globally documented waste from the coal and steel industries.

Australian Iron and Steel Association and Ash Development Association Executive director and industry partner Craig Heidrich said the benefits of the trial will be far-reaching.

“Our collaboration with organisations such as the City of Sydney and the publication of the research findings will further demystify and promote the use of geopolymer concrete in construction,” Mr Heidrich said.

“It’s a fundamental tenet in business that you need to be constantly innovating and investing into new technologies. This trial will provide real examples of geopolymer concrete use that we can all use.”

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