Sask. researcher says filters made of agricultural residue can reduce arsenic levels in water
A chemical engineering graduate student at the University of Saskatchewan is developing a way to lower arsenic levels in drinking water by using agricultural residue.
Some of those levels in Saskatchewan are higher than what Health Canada deems acceptable, but Khaled Zoroufchi Benis is using wheat and canola straw as a filter.
Zoroufchi Benis told CBC Radio's The Afternoon Edition host Garth Materie that other methods used for the removal of contaminants from water, such as coagulation or reverse osmosis, can be expensive and difficult to operate.
"Agricultural residues have high strength and their environmental benign nature and low cost make them available everywhere," he said.
"And also, they are reusable. So we take this advantage and make inexpensive and sustainable material to make filtration systems."
The filtration system was able to reduce 1,000 micrograms of arsenic per litre of water to less than 10 micrograms per litre, he said.
LISTEN | Some Saskatchewan drinking water may contain arsenic:
He said any concentration that is higher than 10 micrograms per litre is toxic for humans.
Arsenic is a known carcinogen that can lead to skin, lung and bladder cancer, as well as other diseases.
According to a Government of Saskatchewan fact sheet, it is a natural element widely found in soil, bedrock and water. Rocks and soil release arsenic into the groundwater.
Arsenic is also released into the environment through the manufacturing of pesticides and the burning of fossil fuels. It is also a byproduct of copper smelting, mining and coal burning, and may enter water supplies through the discharge of industrial wastewater and agricultural pollution.
Arsenic testing in Sask.
According to the Water Security Agency's annual report on the state of drinking water quality in Saskatchewan, there were 32 instances of arsenic exceedances in the province in 2020-21 that were found in samples from 15 human consumptive systems.
It said these cases were discovered through regular required sampling. Additional voluntary arsenic testing was done in 10 human consumptive municipal systems, resulting in 66 additional exceedances, it said.
Zoroufchi Benis said in more than 70 countries, including Canada, about 200 million people are in danger of drinking water with high arsenic concentrations.
He said using ag residue for filtration can also be used for other pollutants, whether they be organic or inorganic.
"Nowadays, we are hearing a lot about chemicals of emerging concern like pharmaceuticals and personal care products that we use every day," he said. "And we are releasing this material to water and wastewater."
He said they activate the agricultural residues by applying a physical and chemical treatment that is contaminant-oriented — meaning that by changing the treatment, the ag residues can absorb other contaminants from water, such as selenium, which is also toxic in higher concentrations.
But he said it will be another five or six years before this research can be applied in industrial or municipal settings for water and wastewater treatment.
