Zero-valent iron granules (> 2 mm).Active towards both phosphate and nitrate
Zero-valent iron is active towards both phosphate and nitrate, and it is primarily thought for final water polishing. Nitrate is chemically reduced to mainly ammonium by zero valent iron. This generates iron oxide (corrosion) products that will strongly bind phosphate.
The principle: Metallic iron (Fe0)reduces nitrate to ammonium (possibly also N2) and the iron oxidation causes iron oxides to precipitate that subsequently binds phosphate. The reduction works both at low and high pH.