Difference between revisions of "Iron filings (ZVI)"
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| − | [[File:Železo.png|thumb|ZVI]] | + | [[File:Železo.png|500px|thumb|ZVI]] |
===What is it?=== | ===What is it?=== | ||
| − | Iron filings or zero-valent iron (ZVI) is the elemental form of iron with a zero charge carried by each atom – a result of the outer valence level being filled. ZVI is able to remove dissolved phosphorus (phosphate) from solution through precipitation (Rossetti, 2017) | + | Iron filings or zero-valent iron (ZVI) is the elemental form of iron with a zero charge carried by each atom – a result of the outer valence level being filled. ZVI is able to remove dissolved phosphorus (phosphate) from solution through precipitation (Rossetti, 2017)<ref name=Rossetti>Rossetti M. 2017. Evaluation of phosphorous removals by biochar supported nano-scale zero-valent iron. Chemical Engineering Undergraduate Honors Thesis.</ref>. Zero-valent iron nanoparticles (nZVI) are also used for [[phosphorus]] removal. |
===How is it being used?=== | ===How is it being used?=== | ||
| − | * A field study in Maplewood, Minnesota used an iron-enhanced (5% iron filings) ditch check sand filter for installation in [[Swales|swales]] to provide treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff from highways (Ahmed at el., 2014) <ref>Ahmed, F., Natarajan, P., Gulliver, J., Weiss, P., Nieber, J. 2014. Assessing and Improving Pollution Prevention by Swales. https://www.lrrb.org/pdf/201430.pdf</ref>. | + | * A field study in Maplewood, Minnesota used an iron-enhanced (5% iron filings) ditch check sand [[Filtration|filter]] for installation in [[Swales|swales]] to provide treatment of dissolved heavy metals and dissolved phosphorous in stormwater [[Runoff volume control target|runoff]] from highways (Ahmed at el., 2014) <ref>Ahmed, F., Natarajan, P., Gulliver, J., Weiss, P., Nieber, J. 2014. Assessing and Improving Pollution Prevention by Swales. https://www.lrrb.org/pdf/201430.pdf</ref>. |
| − | * In Ajax, Ontario, iron filings were tested as an additive in bioretention areas and compared against two alternatives: a bioretention area with 5% sorbtive media, and a typical engineered media bed consisting of a shredded hardwood mulch layer over a sand–soil–organic mixture. Phosphorus concentrations were lowest in the sorbtive media mix, followed by the iron filing mix, while the typical media bed had the poorest removal performance (Aquafor Beech, 2018)<ref>Aquafor Beech Ltd. 2018. Monitoring Report (2015–2017):Rain Garden Performance Monitoring Program: Lake Driveway. https://www.ajax.ca/en/get-involved/resources/Stormwater/Rain-Garden-Performance-Monitoring-Program-Lake-Driveway.pdf</ref>. | + | * In Ajax, Ontario, iron filings were tested as an additive in [[Bioretention|bioretention]] areas and compared against two alternatives: a bioretention area with 5% sorbtive media, and a typical engineered media bed consisting of a shredded hardwood mulch layer over a sand–soil–organic mixture. Phosphorus concentrations were lowest in the sorbtive media mix, followed by the iron filing mix, while the typical media bed had the poorest removal performance (Aquafor Beech, 2018)<ref>Aquafor Beech Ltd. 2018. Monitoring Report (2015–2017): Rain Garden Performance Monitoring Program: Lake Driveway. https://www.ajax.ca/en/get-involved/resources/Stormwater/Rain-Garden-Performance-Monitoring-Program-Lake-Driveway.pdf</ref>. |
| − | [[File:Screenshot 2025-08-13 113919.png|500px|thumb|[[Bioretention]] schematic, with circles highlighting ZVI addition and phosphorus removal <ref name = Lechner>Lechner L. Phosphorus Removal From Stormwater Using Zero-Valent Iron | + | [[File:Screenshot 2025-08-13 113919.png|500px|thumb|[[Bioretention]] schematic, with circles highlighting ZVI addition and phosphorus removal (Lechner, 2016)<ref name = Lechner>Lechner L. 2016. Phosphorus Removal From Stormwater Using Zero-Valent Iron. Applied Science Masters Thesis.</ref>.]] |
===Benefits=== | ===Benefits=== | ||
| − | A study was done that compared the phosphorus reduction capabilities of ZVI, [[biochar]], biochar-supported ZVI (ZVI/BC), and biochar-supported nZVI (nZVI/BC) | + | A study was done that compared the phosphorus reduction capabilities of ZVI, [[biochar]], biochar-supported ZVI (ZVI/BC), and biochar-supported nZVI (nZVI/BC) (Rossetti, 2017)<ref name=Rossetti/>. It was found that nZVI/BC had the highest phosphorus reduction. Using biochar-supported ZVI or nZVI improves the dispersion and stability of the iron filings. Biochar is fine-grained and highly porous, providing a large surface area to support nZVI. |
| − | Another paper reports that ZVI can remove up to 98% of influent phosphorus at low input concentrations, and at high concentrations is shown to remove up to 36% of incoming phosphorus. The phosphorus retained in the soil is mostly iron-bound, which will not be easily leached out of the system because it is very stable | + | Another paper reports that ZVI can remove up to 98% of influent phosphorus at low input concentrations, and at high concentrations is shown to remove up to 36% of incoming phosphorus. The phosphorus retained in the soil is mostly iron-bound, which will not be easily leached out of the system because it is very stable (Lechner, 2016)<ref name = Lechner></ref>. |
</onlyinclude> | </onlyinclude> | ||
Back to [[additives]]. | Back to [[additives]]. | ||
Latest revision as of 15:38, 19 August 2025
What is it?[edit]
Iron filings or zero-valent iron (ZVI) is the elemental form of iron with a zero charge carried by each atom – a result of the outer valence level being filled. ZVI is able to remove dissolved phosphorus (phosphate) from solution through precipitation (Rossetti, 2017)[1]. Zero-valent iron nanoparticles (nZVI) are also used for phosphorus removal.
How is it being used?[edit]
- A field study in Maplewood, Minnesota used an iron-enhanced (5% iron filings) ditch check sand filter for installation in swales to provide treatment of dissolved heavy metals and dissolved phosphorous in stormwater runoff from highways (Ahmed at el., 2014) [2].
- In Ajax, Ontario, iron filings were tested as an additive in bioretention areas and compared against two alternatives: a bioretention area with 5% sorbtive media, and a typical engineered media bed consisting of a shredded hardwood mulch layer over a sand–soil–organic mixture. Phosphorus concentrations were lowest in the sorbtive media mix, followed by the iron filing mix, while the typical media bed had the poorest removal performance (Aquafor Beech, 2018)[3].
Bioretention schematic, with circles highlighting ZVI addition and phosphorus removal (Lechner, 2016)[4].
Benefits[edit]
A study was done that compared the phosphorus reduction capabilities of ZVI, biochar, biochar-supported ZVI (ZVI/BC), and biochar-supported nZVI (nZVI/BC) (Rossetti, 2017)[1]. It was found that nZVI/BC had the highest phosphorus reduction. Using biochar-supported ZVI or nZVI improves the dispersion and stability of the iron filings. Biochar is fine-grained and highly porous, providing a large surface area to support nZVI. Another paper reports that ZVI can remove up to 98% of influent phosphorus at low input concentrations, and at high concentrations is shown to remove up to 36% of incoming phosphorus. The phosphorus retained in the soil is mostly iron-bound, which will not be easily leached out of the system because it is very stable (Lechner, 2016)[4].
Back to additives.
- ↑ 1.0 1.1 Rossetti M. 2017. Evaluation of phosphorous removals by biochar supported nano-scale zero-valent iron. Chemical Engineering Undergraduate Honors Thesis.
- ↑ Ahmed, F., Natarajan, P., Gulliver, J., Weiss, P., Nieber, J. 2014. Assessing and Improving Pollution Prevention by Swales. https://www.lrrb.org/pdf/201430.pdf
- ↑ Aquafor Beech Ltd. 2018. Monitoring Report (2015–2017): Rain Garden Performance Monitoring Program: Lake Driveway. https://www.ajax.ca/en/get-involved/resources/Stormwater/Rain-Garden-Performance-Monitoring-Program-Lake-Driveway.pdf
- ↑ 4.0 4.1 Lechner L. 2016. Phosphorus Removal From Stormwater Using Zero-Valent Iron. Applied Science Masters Thesis.