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Intercepting phosphorus with a nanoparticle filtration system

Researchers explore nanoparticle filtration.


November 21, 2019
By Julienne Isaacs

Topics
Installation of the filtration tank.

An innovative new project will test a unique nanoparticle filtration system for its ability to remove soluble phosphorus from agricultural runoff.

The site of the project is on 70 acres of land belonging to the Chippewas of the Thames First Nation and leased by a grain farmer. The filtration system will target tile water flowing into a municipal drain outlet.

The Chippewas experiment is one of seven new demonstration projects led by the Thames River Phosphorus Reduction Collaborative (TRPRC) that aim to intercept and remove phosphorus runoff from agricultural systems in order to limit algal blooms on the Thames River and in Lake Erie. Five of these projects, including the Chippewas project, were implemented in spring or early summer 2019, with another two set to begin by 2020.

The TRPRC represents a collaborative effort between many groups, including the Ontario Federation of Agriculture (OFA) and the Great Lakes and St. Lawrence Cities Initiative, the drainage industry, farm organizations, environmental groups and First Nations groups, says Charlie Lalonde, project director for the TRPRC.

The collaborative is funded through Environment and Climate Change Canada’s Great Lakes Protection Initiative as well as the Canadian Agricultural Partnership, a federal-provincial-territorial initiative; an additional ten groups contributed funding, according to Lalonde.

Most of these organizations have identified agricultural runoff as an important issue – for example, OFA is involved in 4R Nutrient Stewardship, and Grain Farmers of Ontario is involved in cover crop and soil health initiatives, says Lalonde – but this is the first initiative that brings the industry together to focus on the role of drainage in contributing to the P load in Lake Erie.

“As a result, we oriented these projects exclusively in that space,” Lalonde says. “Together we wanted to look at potential solutions to reduce agriculture’s impact on Great Lakes water.”

Project site

Lalonde says the TRPRC wanted to find sites representing diverse agricultural settings for its projects.

The Chippewas project is located on a grain operation with a corn-soy-winter wheat rotation, and both the farmer and the Chippewas of the Thames First Nation (COTTFN) were interested in understanding how agricultural runoff impacts water quality in the region, says Emma Young, senior environment officer for COTTFN.

COTTFN community members have participated in the TRPRC since the beginning, she says.

“We do a lot of projects internally in our community, and a lot of that is focused on water,” Young says. “Since 2016 we’ve started a regular benthic testing regime in the spring and fall, and we do fish sampling each year. We also worked with the Canadian Environmental Law Association to look at our source water.”

The First Nation’s drinking water comes from the Thames, and it’s considered ground water under the influence of surface water, says Young. Last year, in collaboration with Western University, COTTFN began testing water samples, targeting areas surrounded by agricultural land before and after the wastewater treatment plant to monitor P and nutrient loading.

“Our numbers were high – above the government recommended P quantities for water,” she says. “This paired perfectly with the work Charlie wanted to do. We looked at potential locations the project could go, and we wanted it to be on one of the areas where we have been doing P testing because we already have some data. The puzzle pieces fit together quite well.”

Once a drain enters First Nations land, it’s no longer considered a municipal drain or subject to the Ontario Drainage Act, says Young, which means COTTFN has the power to implement projects affecting drain water within its territory. Nevertheless, the TRPRC has involved the municipality throughout project development and implementation to ensure the hydrological flow was not impeded. Young says both the municipality and the farmer leasing the land have been supportive of the project since the beginning.

Experiment site locations are indicated with pins.

Filter design and monitoring

Gary Walker is owner of GA Phosphorous Solutions (GAPS) and former general manager of Silt Sock Environmental (SSE), the erosion control company that manufactured and installed the filter at the Chippewas site.

Walker says the design and technology behind the filter was developed by American-owned ESSRE Consulting.

The filter was installed in June in an edge-of-field closed drain system at the site. SSE diverted a 12-inch main that drains the 70 acres into a 1,250-gallon plastic septic tank modified to allow drained water residence time in AbTech Smart Sponge and MetaMateria PO4 sponge installed within the tank.

PO4 Sponge is a porous material containing iron-oxyhydroxide nanocrystals that provide “an extremely large number of sites for phosphate ion sorption,” according to MetaMateria’s website.

“PO4 sponge gives you a huge, huge surface area. A thousand times greater than any other absorption technology out there,” Walker explains.

Phosphorus capture is effective in PO4 sponge at both high and low concentrations, MetaMateria claims; capture at concentrations below 0.03 mg/L is possible.

Walker says the material is pricey but worth it. “It’s similar to your mortgage – you can amortize it over 20 years. We have testing showing that you can take out the sponge, clean it and reuse it up to 20 times. The capture of P allows for reuse and is the beginning of a circular economy.”

Walker says the material is pricey but worth it. “It’s similar to your mortgage – you can amortize it over 20 years. We have testing showing that you can take out the sponge, clean it and reuse it up to 20 times.”

GAPS will be responsible for ongoing monitoring and maintenance at the site, says Walker. So far, not much water has been running through the filter, but the real test of its mettle will come during heavy runoff periods in winter and spring. Remote monitoring technology is available but not installed at this site, which means Walker will visit the site after multiple days of precipitation to test for soluble P and nitrates.

Eventually, Walker intends to collaborate with Western University researchers and ESSRE Consulting to investigate potential applications for reusing the concentrated P collected from the filter – in commercial greenhouses, for example, or home gardening.

According to Lalonde, the TRPRC project doesn’t stop at nanomaterial, but will also test biochar and other filtration materials at two additional sites beginning next year.

Walker says the idea of using nanotechnology sponge has been tested in the U.S. but, until now, hadn’t yet been tried in Canada.

He believes that in the absence of meaningful incentives, the material is likely too expensive to be a feasible option for farmers. However, its effectiveness in tests makes it an option worth exploring.

“I’m confident that with the environmental movement, we’re not going to have any alternatives down the road other than to do something like this,” he says. “Awareness of this technology will give drainage contractors a leading edge.”

As far as the effort to clean up Lake Erie goes, Lalonde, Walker and Young agree industry-wide collaboration and communication is the only way forward.

“Water impairment in Lake Erie is a serious issue and it’ll take considerable effort to bring about some changes,” Lalonde says. “On the one hand, cities have to do their part to improve water quality, but we have to do our part in agriculture as well.”

Young says the effort will require, “everyone coming together.”

“I don’t think just the scientific community or the drainage industry or First Nations will solve it. We all have strengths that when we pull together are so much stronger.”

The nanoparticle filtration system will target tile water flowing into a municipal drain outlet.

The nanoparticle filtration system will target tile water flowing into a municipal drain outlet.

Additional projects

The Chippewas experiment is one of seven new demonstration projects led by the Thames River Phosphorus Reduction Collaborative (TRPRC) that aim to intercept and remove phosphorus runoff from agricultural systems in order to limit algal blooms on the Thames River and in Lake Erie. Five of these projects were implemented in spring or early summer 2019, with another two set to begin by 2020.

Boudreau Pump Station

Site: The Boudreau pump station is located on Merlin Road in Chatham-Kent, ON. It services approximately 340 acres of land in row crop production. Two fields are systematically tiled and drain via two channels. These deliver mostly tile water to the pump station, where it’s pumped from the municipal Deary drain to Jeanette’s Creek, which discharges into the Thames River. The soils vary from a Brookston clay to a silt clay loam. Soil P readings are moderate to high (20 to 47 ppm) and the soils have high organic matter (4.7 to 7.6 percent). The Lower Thames Valley Conservation Authority (LTVCA) has monitored this site under the Great Lakes Agricultural Stewardship Initiative (GLASI) since 2016. Water quantity and quality data is available.

Partners: LTVCA, Waterloo Biofilter, Thames River PRC

Research description: Waterloo Biofilter is the technology provider. The system is based on electro chemistry to coagulate dissolved P followed by a foam filter to support biological digestion. The electro chemistry will transform dissolved P into particulate for the digestion phase.

Measurements: Pounds of P removed will be the metric, and calculated using data on total P.

Progress: Initial samples taken in late 2018.

Roesch Farm

Site: A 100-acre farm situated east of Chatham, ON. Crops are seed corn, soybeans, specialty beans and winter wheat. There is a pig barn on the farm, and crops receive manure from it annually.The 100-acre field is tiled, with a 12-inch outlet on each 25-acre lot that empties into the municipal McKinley drain, and then to the Thames. The soil is a very fine clay loam with phosphorus (P) readings of 50 to 65 ppm. It has a very slow infiltration rate (hydrologic soil group D).

Partners: Ontario Ministry of Agriculture, Food and Rural Affairs responsible for the model to calculate P recovery and water flow. Lower Thames Valley Conservation Authority maintains the 25-acre site, conduct sampling and have the water analyzed. Thames River PRC providing funding to support sampling.

Research description: One 25-acre field is being used to measure P removal using a Filtrexx Nutrilock sorption material. Testing began in April 2018. Tile water is channeled through two tanks where P is absorbed. In the fall of 2018, modifications were made to the tile to channel water to the treatment tanks by Gillier Drainage. A weather station will be added in 2019.

Measurements: Pounds of P removed will be the metric, and calculated using data on total P and dissolved P for the technology’s efficiency.

Progress: Installation and start-up in April, 2018.