from the Conversation by Professor William Clarke December 16, 2022

Only 24% of local councils in Australia separately collect household food organics and garden organics (FOGO) waste. Another 16% provide garden waste collection only. This limited progress has prompted the federal government to push back the target date, from 2023 to 2030, for all councils to collect food and garden waste separately from landfill waste.

Most food waste currently goes into red bins as mixed waste bound for landfills. Kerbside collection of organic waste will become a standard service for all residents in New South Wales and Victoria by 2030, for metropolitan residents in South Australia and Western Australia by 2025 and for Canberra residents by 2023.

To achieve these targets, effective policies and incentives will need to be put in place for councils or private waste management companies. They will have to build and operate the infrastructure needed to process FOGO waste, and will want to recoup their costs.

Happily, this waste has increasing value as a source of both high-quality compost and biogas, which can be used like natural gas. The markets for these products, with gas prices in particular soaring, should help drive widespread adoption earlier than 2030.

---

Read more: Four bins might help, but to solve our waste crisis we need a strong market for recycled products

---

 

Why collect this waste separately?

The rationale for diverting organic waste from increasingly limited landfill space is clear. Collecting this waste separately reduces landfill impacts and costs, while delivering other environmental benefits.

Organic waste in a landfill will biodegrade slowly, eventually turning into biogas (methane and carbon dioxide). It can also produce organic acids that dissolve and mobilise heavy metals, creating a toxic hazard.

Modern landfills operate for decades. Waste is covered as it is placed, but only with soil until the landfill is full. Despite the use of multi-layer liners and impermeable final covers, these eventually deteriorate. In addition to harmful local environmental legacies of landfills, emissions of methane – a potent greenhouse gas – cause global harm.

In contrast, returning clean organic material to soils is beneficial. Australia’s arable soils are typically low in organic carbon, which needs to be regularly supplemented.

---

Read more: We need more carbon in our soil to help Australian farmers through the drought

---

But, to produce high-quality compost, FOGO must be collected in a separate bin to avoid contamination. It’s possible to extract organic material from mixed (red bin) waste. This is done by grinding the waste and then using magnets, eddy currents, water flotation and air sorting to remove glass, plastic and metal fragments.

However, red bin waste is not closely monitored. It can contain batteries, electrical goods, paints and other sources of heavy metals in dissolved or fine-particle form.

This is why NSW banned the use on land of compost derived from mixed waste in 2019. A NSW EPA review had identified cadmium, zinc and copper as metals of high concern in this compost. It also found chemicals such as flame retardants and disinfectants were household sources of persistent organic pollutants.

How much waste are we talking about?

The size and composition of the FOGO resource will change if Australia achieves the UN Sustainable Development Goal of halving the food waste generated per person by 2030, compared to 2015. The 2019 National Waste Policy and Action Plan adopted this goal.

Estimates of food waste in Australia vary. The most comprehensive survey was a nation-wide audit in 2020 of 450 kerbside bins by the Fight Food Waste Cooperative Research Centre. It showed weekly food waste was 0.79kg per person, including 0.34kg of inedible peels, bones and expired or perished food. These households disposed of a similar amount of food waste in the home by composting, feeding to pets or flushing down the sink.

The United Nations Environment Programme’s 2021 estimate is similar at 1.5-1.7kg of weekly food waste per person. The National Waste Database estimate for Australia is higher at 2.37kg.

According to the database, 31% of food waste in NSW was separately collected and composted or digested in 2018-19. The figure was less than 10% in all other states except Western Australia, where it was 13%.

As for garden waste, 2.01kg per person each week goes into kerbside bins. Over 50% of garden waste (85% in South Australia) is separately collected in all mainland states.

 

---

Read more: Why ‘best before’ food labelling is not best for the planet or your budget

---

How can collection costs be covered?

The demand for organic carbon in Australian soils far exceedsthe amount of compost that could be produced from FOGO. But, to tap into this market, the compost quality must be consistent.

A clear definition of acceptable FOGO and carefully controlled operations are needed to produce consistent quality compost. The waste management industry and advice to government have called for FOGO bins to be limited to food waste and garden waste, excluding materials like paper, cardboard and animal waste.

Many councils compost garden waste on open pads, some under cover. Machinery is used to shred and turn over the piles to control temperature and moisture levels.

The control of this process becomes more critical for FOGO. Food waste can be smelly, particularly if the composting process is open to the air but not adequately aerated.

Tighter control, particularly of odour, can be achieved if composting is done in vessels. Typically, these take the form of concrete tunnels.

High-quality compost for farming can fetch A$50 to $80 per cubic metre. That makes separate collection and processing of bio-waste more attractive financially.

In addition, surging gas and electricity prices and the revival in value of renewable energy credits have increased the viability of first anaerobically digesting FOGO to produce biogas, then composting the digested material. FOGO can be digested in sealed tunnels similar to composting tunnels.

---

Read more: Capturing the true wealth of Australia’s waste

---

This biogas will not solve Australia’s gas shortage (FOGO biogas could meet about 2% of the demand). However, I calculate, as a conservative figure, that the income to an anaerobic digestion operator would exceed $40 per fresh tonne of waste. This figure is based on a conservative methane yield of 50m³ per tonne, a wholesale electricity price of $200 per MWhr and a renewable energy credit value of $50 per MWhr.

All of these considerations indicate we should be confident almost all households will have a FOGO service before 2030. The alternative is to waste this resource in landfills, with all their future environmental liabilities.

 

---

Capturing the true wealth of Australia’s waste

August 24, 2017

One of the byproducts of landfill is “landfill gas”, a mixture of mostly methane and carbon dioxide generated by decomposing organic material. Methane is a particularly potent greenhouse gas, but it can be captured from landfill and used to generate clean electricity.

Methane capture is a valuable source of power but, more importantly, it can significantly reduce Australia’s methane emissions. However the opportunity to produce energy from waste is largely being squandered, as up to 80% of the potential methane in waste is not used.

If more councils were prepared to invest in better facilities, Australians would benefit from less waste in landfill and more energy in our grids. Even the by-product from using state-of-art processing methods can be used as a bio-fertiliser.

---

Read more: Explainer: how much landfill does Australia have?

---

And while these facilities are initially more expensive, Australians are generally very willing to recycle, compost and take advantage of community schemes to reduce waste. It’s reasonable to assume that a considerable percentage of our population would support updating landfill plants to reduce methane emissions.

Recycling in Australia

Australia may have a bad rap when it comes to waste recycling, but there are plenty of positives.

Australians produce approximately 600 kilograms of domestic waste per person, per year – no more than most northern European countries, which set the benchmark in sustainable waste management.

Looking at kerbside bins we, on average, recycle 30-35% of that waste, saving much of our paper, glass, aluminium and steel from landfill (which also saves and reduces emissions).

Although the household recycling rate in Australia is less than the best-performing EU recycling rates of 40-45%, this is primarily due to a lack of access to (or awareness of) schemes to recycle e-waste and metals. Data therefore suggests that at the community level, there is a willingness to minimise and recycle waste.

---

Read more:

Australia is still miles behind in recycling electronic products

Campaigns urging us to ‘care more’ about food waste miss the point

---

Between 55% and 60% of kerbside waste sent to landfill in Australia is organic material. Over 65% of this organic fraction is food waste, similar to the make-up of the EU organic waste stream, comprised of 68% of food waste.

Despite this large fraction, approximately half of the household organic we produce – mostly garden waste – is separately collected and disposed, again demonstrating high participation by the community in recycling when collection and disposal options are available.

Turning waste into energy

Energy recovery from waste is the conversion of non-recyclable material into useable heat, electricity, or fuel. Solid inorganic waste can be converted to energy by combustion, but organic waste like kitchen and and garden refuse has too much moisture to be treated this way.

---

Read more: Explainer: why we should be turning waste into fuel

---

Instead, when organic waste is sent to landfill it is broken down naturally by microorganisms. This process releases methane, a greenhouse gas 25 times more potent than carbon dioxide.

Around 130 landfills in Australia are capturing methane and using it to generate electricity. Based on installed power generation capacity and the amount of waste received, Australia’s largest landfills use 20-30% of the potential methane in waste for electricity generation.

Ravenhall in Melbourne processes 1.4 million tonnes of waste per year, and proposes to generate 8.8 megawatts (MW) of electricity by 2020. Roughly 461,000 tonnes of waste goes to Woodlawn in NSW, and in 2011 it generated 4MW of electrical power. Swanbank in Queensland receives 500,000 tonnes a year and generates 1.1MW.

The remainder of the methane is flared due to poor gas quality or insufficient transmission infrastructure, is oxidised as it migrates towards the surface of the landfill, or simply escapes. The methane generating capacity of waste is also diminished because organics begin composting as soon as they reach landfill.

But there are more efficient ways to capture methane using specialised anaerobic digestion tanks. The process is simple: an anaerobic (oxygen free) tank is filled with organic waste, which is broken down by bacteria to produce biogas. This is similar to the natural process that occurs in landfill, but is much more controlled and efficient in a tank.

---

Read more: Biogas: smells like a solution to our energy and waste problems

---

The biogas can be combusted to produce electricity and heat, or can be converted to pure biomethane to be used either in the mains gas grid, or as a renewable transport fuel. In contrast to landfills, 60-80% of the methane potential of waste is used to generate electricity in anaerobic digesters, with most of the remainder used to power waste handling and the digestion process.

The nutrient-rich sludge that remains after anaerobic digestion, called digestate, is also a valuable biofertiliser. It can support food production, and further reduce greenhouse gases by decreasing our reliance on energy-intensive manufactured fertilisers.

The use of food waste as a feedstock for anaerobic digestion is largely untapped in Australia but has huge potential. A site in Sydney’s geographic centre (Earth Power Technologies) and Richgro’s Jandakot facility near Perth are part of a handful that are converting food waste to energy using this technology.

The future of organic recycling

Local council recycling and waste infrastructure is typically not a priority election issue, except for those close to existing or proposed landfills.

---

Read more: Australian recycling plants have no incentive to improve

---

Ratepayers are generally not informed of the possibility of separately collecting food waste, either for industrial-scale composting or methane capture. We have the right to this information, with costs and benefits presented in the context of the costs we already pay for waste management, and relative to the environmental performance of landfill.

As an example, landfill operators often promote the number of homes they power by electricity generated from methane as a key measure of sustainability. But how does this compare to the electricity and heat that might be obtained from an anaerobic digester that processes the same waste?

Given the choice, the Australian community may have an appetite to extend organic recycling beyond well-established garden waste composting. They only have to be asked.