Waste as a resource

with Katie Macintosh

How do you turn poo into a commodity?

By transforming waste that is currently doing harm, researchers hope to produce biogas that can be used as a renewable alternative to fossil fuels.

Image: PhD candidate Katie Macintosh in her lab at UQ's Advanced Water Management Centre.

Approximately 1.4 billion tonnes of organic waste is disposed of in landfills around the world each year, enough to fill 560,000 Olympic swimming pools.

If left to degrade, the waste produces vast amounts of methane, exacerbating climate change through uncontrolled greenhouse gas emissions. But what if these emissions could be harnessed to produce a sustainable source of energy?

The same materials the world currently views as waste would be recast as fuel and valued as an important resource in a sustainable energy future.

The process of converting organic material into methane (biogas) through microbes in oxygen-free environments is known as anaerobic digestion and occurs naturally in places like landfills. This same process can be used in controlled environments – like our laboratory, where the methane can be captured and used to create energy through combustion.
Anaerobic digestion is commonly used throughout the world to treat municipal and agri-industrial organic waste, producing biogas and on-site heat and power. However, many of these existing systems have spare capacity and could be utilised to treat even more waste. The efficiency of these systems could also be improved to maximise biogas production within their existing infrastructure.

One of the key ways to improve efficiency is through the use of anaerobic co-digestion (AcoD), a promising strategy incorporating two or more different and complementary waste streams to optimise biogas output.
AcoD offers many benefits, including the promotion of integrated waste management between industries, diversion of organic waste away from landfill which limits greenhouse gas emissions, and increased revenue for industry through increased energy production.

AcoD is able to combine low-energy waste, such as livestock manure or sewage sludge, with small amounts of high-energy waste, such as fats, oil and grease.

Researchers in the Anaerobic Technologies team at the Advanced Water Management Centre (AWMC) are enhancing our fundamental understanding of AcoD risks and drivers, to help municipalities and industries improve their management of waste.

This fundamental research will inform a comprehensive co-digestion model and manual aimed at enabling industry to evaluate cost-benefit and risk of various wastes and combinations of waste for co-digestion.

These tools will enable industry collaborations for multiple types of wastes to be treated on-site, reducing organic waste sent to landfill and reliance on the fossil-fuel driven electricity grid.
Optimisation of the anaerobic digestion process will ensure that surplus organic materials are no longer viewed as waste, but as a resource, powering a sustainable and environmentally sound future.

View Katie's Three Minute Thesis (3MT) talk on this topic 'Waste is Power' here.

Researchers Katie Macintosh and Mike Meng are examining the production of biogas.