FerroSorp® PN

Colloidal iron hydroxide nitrate gel for internal water body restoration


The eutrophication of bodies of water is one of the most common water quality problems worldwide. Eutrophication, in for example drinking water extraction, fish farming or swimming, often lead to efforts to improve the trophic situation. An excessive availability of phosphorus in water and sediment is seen as the main factor in increased biomass and thus the eutrophication of bodies of water. Phosphorus, however, also represents the limiting factor for eutrophication, i.e. a controlled reduction of the concentration of plant-available phosphorus can effectively limit eutrophication.

14 Pb FerroSorp PNß

Photographic representation of the interface between anaerobic sediment and oxygen-rich cover with FerroSorp® PN


FerroSorp® PN was specifically developed for preventing the phosphorus re-dissolution processes. This product is a new type of iron compound with a high nitrate storage capacity which releases the built-in nitrate very slowly. This process overcomes the problem of high water solubility and thus the mobility of free nitrate.


FerroSorp® PN is an iron (III) hydroxide gel that forms a three-dimensional, highly-molecular, colloidal network due to progressive condensation in the production of iron nitrate. In this process, nitrate is already included in the formation of the macromolecular matrix and bound by both ionic and absorptive processes. After the addition of this suspension into a body of water, large flakes settle rapidly and form a surface layer on the muck. Due to the contained nitrate, which by way of diffusion slowly pass into the surrounding water, the redox potential in proximity of the sediment is kept at a high level over a long period. The desulfurization and methanogenesis are inhibited, and a phosphorus re-dissolution is virtually completely prevented by the absorption from the iron hydroxide. Based on a further mineralization of the sediment as a result of the initiated microbial activity by the addition of nitrate, the nutrient potential in the muck is also sustainably reduced.


From our present perspective FerroSorp® PN can be advantageously used in the following applications:

  • Restoration of eutrophic surface waters (lakes, industrial storage tanks)
  • Remediation of contaminated water sediments (eg in port areas or industrial storage tanks) by
    • Sediment oxidation
    • Microbial degradation of organic contaminants (eg. as TPH, PAHs)
    • Binding of heavy metals and phosphorus
    • Reduction of hydrogen sulfide odors due
    • Sediment solidification
    • Preventing resuspension and saltation

Structur of FerroSorp® PN gel

14 Pb FerroSorp PN

Advantages at a glance

  • Very sustainable process for internal water restoration due to depot effect
  • Easy handling
  • Combined effectiveness in a one-step Application
  • Very economical process for the treatment of small and medium bodies of water