Iron filings (ZVI)
What is it?[edit]
ZVI is scrap iron filings and describes 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]