Mining liquid gold in city parklands

Griffith University researchers are part of a new trial to turn human urine into fertiliser in city parklands, reshaping the future of wastewater infrastructure.

Under the $2 million ARC Research Hub for Nutrients in a Circular Economy (NICE), researchers from Cities Research Institute (CRI) are investigating the economic feasibility and practically of converting human urine to fertiliser as well as any potential health risks and the public response.

Chief Investigator Associate Professor Cara Beal from Cities Research Institute

Chief Investigator Associate Professor Cara Beal from CRI says human urine is a treasure trove of nutrients.

“It’s a concentrated supply of all the nitrogen, phosphorus and potassium needed for plant growth and is surprisingly clean compared to other waste,” she said.

“Current methods to create fertiliser pull nitrogen out of the atmosphere in an energy intensive process with a massive carbon footprint. As a society, if we are to get to net zero carbon emissions we are going to have to move away from synthetic fertilisers.

“Phosphorus on the other hand is mined, with supplies forecast to last no more than 100 years, so it makes no sense to flush these essential nutrients down the toilet.”

NICE aims to change the wastewater industry by creating an unprecedented, city-scale circular flow of nutrients based on urine separation and processing at building level, to produce safe and effective liquid fertilisers.

“We’re workingto determine the value of urine-based fertiliser and the impact it can have on soil and plant production,” Associate Professor Beal said.

“Human urine contains most of the nitrogen we consume, about ten grams per litre and about a gram of phosphorus, making it a perfect source of nutrients to grow crops we eat, in an ongoing sustainable cycle.”

Historically, humans used urine as both a fertiliser and a cleaning agent. But more recently, for the past 100 years up to 1970’s, farmers used combined human waste as a fertiliser on fields.

“Only recently have humans become squeamish about recycling the waste we produce to grow essential food crops and other plants,” Associate Professor Beal said.

“Part of our research will investigate why we have become uncomfortable with the idea of harvesting urine for fertiliser, and how we can temper this concern.

“The public and regulatory authorities have legitimate concerns around potential health issues the technology could pose, with the antibiotics, drugs, hormones and other chemicals we consume that end up in our waste streams.”

The team will assess the health risks and how to positively engage both public and regulatory authorities around the safety and efficacy of the nutrient extraction technology to trap the good nutrients from urine we want to reuse, while simultaneously removing all the unwanted chemicals.

“Designing wastewater infrastructure to tackle urban intensification, waterways pollution and climate change is important on a national and global scale,” said Associate Professor Beal said, who played a leading role in designing such urine separation systems for Currumbin Ecovillage.

Other Hub research partners include University of Technology Sydney (lead organisation), University of Melbourne, Western Sydney University and University of Southern Queensland.