Phosphorus recycled from wastewater for better crops

Results of treating water with biochar: Untreated on left, middle tubes have biochar and the right tube shows effluent after filtration with biochar. (Photo courtesy Canadian Light Source)

MOSCOW, Idaho — 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,” said 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 at University of Saskatchewan, 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.
“With the CLS, we were able to confirm how efficient the biochar is at removing phosphorous and what its value is going to be when we add it to the soil,” said Strawn.
The biochar-water treatment process developed by Strawn and his collaborators has received a patent, which is owned by the University of Idaho.
“We’re hitting on many factors,” said Strawn. “We are recycling phosphorus, producing cleaner water, increasing soil health, and are creating a carbon sink that reduces atmospheric greenhouse gases, so it really is a multifaceted technology.”