Iron filings (ZVI)

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ZVI

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 phosphate from solution through precipitation. [1] Zero-valent iron nanoparticles (nZVI) are also used for phosphorus removal.

How is it being used?[edit]

No projects that use ZVI were found in Ontario.

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). [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.[2]


  1. 1.0 1.1 Rossetti M. Evaluation of phosphorous removals by biochar supported nano-scale zero-valent iron. 2017. Chemical Engineering Undergraduate Honors Thesis.
  2. Lechner L. Phosphorus Removal From Stormwater Using Zero-Valent Iron. 2016. Applied Science Masters Thesis.