Recycling phosphorus from wastewater to grow better crops

Scientists are helping close the loop on the sustainability cycle with research into nutrient-enhanced biochar — a charcoal-like material made by heating recycled biomass in the absence of oxygen (a process called pyrolysis). Biomass is any living or once-living material – including plants, trees, and animal waste — that can be used as a source of energy.

Daniel Strawn, Professor of Environmental Soil Chemistry at the University of Idaho, and his colleagues are interested in enhancing biochar – which can be used as an amendment to promote soil health — by adding phosphorus, a crucial nutrient for crops.

The research team, which also included scientists from the University of Saskatchewan and Washington State University, has focused its efforts on recovering phosphorus from wastewater.

“Phosphorus is a limited resource, taken out of the ground, processed to produce fertilizer, and eventually it ends up in wastewater,” says Strawn. “We are developing technology to recover it using biochar in a water treatment process.”

Biochar is an effective sponge ­that can soak up phosphorous and other nutrients, like nitrogen, from waterways. The team is testing this treatment process on municipal and agricultural wastewater systems.

With the help of the Canadian Light Source (CLS) at USask, Strawn and his colleagues confirmed in a recent paper which type of phosphorous had been absorbed by the biochar — a crucial step to understanding and refining their process.

Read more on the CLS website

Dublin researchers study phosphorus cycling and water quality

Using the Canadian Light Source at the University of Saskatchewan, Trinity College Dublin researchers have studied long term phosphorus storage and release in environmental systems, information which can help guide water quality management.

Phosphorus applied to agricultural crops is stored in various mineral and organic forms. This accumulated phosphorus is termed “legacy phosphorus” and can take decades to eventually mineralize and leach back into aquatic systems in a form living things can use.

“Phosphorus in lake and river systems is being recycled back into the water column degrading water quality through weed and algal growth cycles which can initially be exacerbated if phosphate inputs are stopped or significantly reduced” said Dr. David O’Connell, Assistant Professor of Contaminant Hydrology and Hydrogeology at Trinity College Dublin.

He recently published two papers with international collaborators that explore legacy phosphorus in river and lake systems, elucidating the processes and mechanisms through which phosphorus is stored and released in these systems over the long term.

Read more on the CLS website

Image: Flow measurements at the Bunuoke catchment.

Credit: Dr. David O’Connell