Struvite

All modern agriculture today depends on the addition of nitrogen, potassium and phosphorus.  Two of those are mined and form rich finite resources.  for that reason alone recyling is indicated.

Here we learn that all waste water is phosphous rich and can by readily usded as feed  stock in an industrial grade operation. Good to know while we spray a lot of this on our feilds to do the same job.

what i do want to see is struvite and perhaps even potash and urea been combined properly with biochar. This grabs the nutrients and prevents dissolved product escdaping into ground water.

All this can support a virtuos cycle of general nutrient recovery for agriculture.  Not so easy of course, but hte objective seems attainable...

What is struvite and how is it used?

Recovered phosphorus from wastewater can be reused on farmland

February 15, 2022 – Phosphorus is one of the main “ingredients” for healthy plant growth. Plants get phosphorus from the soil. And much of this phosphorus is applied to farm fields in the form of

 fertilizers.

The major current source of phosphorus, which comes from rock, is running out. Plus, it must be mined, and then chemically converted and transported long distances. This costs money and uses valuable resources. The Soil Science Society of America’s (SSSA) February 15th Soils Matter blog takes a look at research that is making a circular phosphorus cycle through struvite reclamation.

Bloggers Kristofor R. Brye, University of Arkansas, and Lauren Greenlee, Pennsylvania State University, write about their research into reclaiming phosphorus – in the form of struvite – from wastewater treatment plants.

Research is looking at alternative ways to retrieve phosphorus, such as in the form of struvite. Struvite is a chemical compound that contains not only phosphorus, but magnesium and other elements like nitrogen. All of these are important nutrients for crops. Struvite has shown promise for use in agriculture as an alternative fertilizer-phosphorus source. Both greenhouse and row-crop studies suggest that struvite is a viable fertilizer compound, compared to traditional fertilizers.

Wastewater treatment plants work to purify water so that it can be reused. They fall under strict standards from the Environmental Protection Agency. Struvite can precipitate from wastewater in similar ways to rock candy formation. Scientists have found that it is not only possible to pull struvite from wastewater, but that it can be done on a large scale. Brye and Greenlee’s teams used both chemical and electrochemical methods to precipitate the struvite from the wastewater.

Their field studies also showed the struvite’s slow release of phosphorus may benefit the environment.

2022 marks the 50-year anniversary of the Clean Water Act. This Act aims to restore and maintain the physical, chemical, and biological integrity of the nation’s water resources. Struvite may play a future role in accomplishing the objectives of the Clean Water Act. Struvite may also play an integral role in supporting the sustainability of agriculture and food production with recycled nutrient fertilizer sources.

Research about struvite and its uses will help keep people fed and protect the environment, just as the Clean Water Act envisioned.

Drs. Brye and Greenlee recently published their research in Agrosystems, Geosciences & Environment Journal, a publication of the American Society of Agronomy and the Crop Science Society of America. To learn more about this important work, visit the Soils Matter blog: https://soilsmatter.wordpress.com/2022/02/15/what-is-struvite-and-how-is-it-used.

Photo: (Left) Pelletized, chemically precipitated struvite by Ostara Nutrient Recovery Technologies Inc. Recovering struvite from wastewater can benefit the environment. (Right) Powdered, electrochemically precipitated struvite created in the laboratory from synthetic wastewater. Credit: Niyi Omidir.

For more high res photos, please contact Caitlin Heitman, cheitmank@sciencesocieties.org.

Study shows struvite good phosphorus source for crops

Retrieving struvite from wastewater reduces the amount of phosphorus entering the environment, replaces mined phosphorus

February 16, 2022 - Studying new fertilizer options is the first step to getting farmers to eventually use them on their crops. A mineral called struvite has the potential to be an effective phosphorus fertilizer that may be considered organic.

Joanne Thiessen Martens, researcher from the University of Manitoba - Canada, along with collaborators, studied how struvite impacted three crops. These were spring wheat, flax, and an alfalfa-grass forage mixture.

“Struvite is a naturally occurring mineral that can be extracted from nutrient-rich wastes, such as municipal wastewater or manure,” Thiessen Martens says. “It is rich in phosphorus and seems to be a relatively good phosphorus fertilizer.”

She adds that recovering the fertilizer from wastewater also reduces the amount of phosphorus entering the environment. Excess phosphorus can be harmful to the environment.

The research was recently published in the Agronomy Journal, a publication of the American Society of Agronomy.

In their study, they applied struvite to fields of the three crops at different rates. They then looked at yields from the crops and measured how much phosphorus the crops contained after harvest. Their goal was to find the best application rate of struvite that provided a good amount of phosphorus to the crops.

“The main thing we were looking for was an increase in the grain yield or the forage biomass yield when crops were fertilized with struvite,” Thiessen Martens says. “A key part of our study was to see how the struvite application rate affected these different indicators of a good phosphorus supply.”

Their results showed that struvite increased the grain yield of spring wheat, but not flax. The alfalfa-grass forage responded very well to the fertilizer. The researchers also noted that the benefit to the alfalfa-grass increased in the second and third years of the study. Thus, the struvite applied in 2017 provided an even greater benefit in 2018 and 2019 than it did in 2017, the year it was applied.

Although they don’t know for certain why the crops responded differently, they have some ideas. It may be because they get nutrients from the soil in different ways. Flax, for example, gets help from fungi in the soil to get phosphorus. This may be why is doesn’t respond well to struvite.

Crops like alfalfa produce acids that help dissolve phosphorus in the soil and that may have been why it responded well to the fertilizer. The scientists want to perform more research to learn more about the differences between crops and the reasons for these differences.

They found that high rates of application created the best results. They also saw that a lot of the struvite was not recovered by the crop. This means it was not taken up by the plants and was left in the soil. The scientists want to further study what happens to the unused struvite in the soil.

In examining the different rates of fertilizer applied, the researchers found that they did not reach an amount of fertilizer that maxed out the crops’ response. To establish that maximum crop response to a certain fertilizer, they would need to have application rates where crop yield or phosphorus accumulation levels off.

“Based on our results, we can say that the recommended phosphorus application rates, which correspond to our lowest application rates, were not adequate at this site,” Thiessen Martens explains. “But we don’t know enough from this study to say whether fertilizer recommendations in general need to be revisited.”

She adds that much of the research on the circular economy for nutrients has been focused on how to recover fertilizers like struvite from waste. However, it’s also important to do more research on how to use these recycled fertilizers.

“These recycled fertilizers do not behave the same in the soil as soluble fertilizers do,” she says. “It’s one of the practical aspects that needs to be worked out so we can apply the idealistic notion of the circular economy more broadly.”

This research was funded by Agriculture and Agri-Food Canada and Ostara Nutrient Recovery Technologies.

Photo Caption: Remnants of struvite granules found in the soil in spring 2019, about one year after application in the wheat experiment. Leftover remnants indicate the struvite granules were only partially dissolved in soil and absorbed by the plants and were left in the soil. Credit: Joanne Thiessen Martens.

For high-resolution photos please contact Caitlin Heitman, cheitman@sciencesocieties.org