Granular iron hydroxide for effective removal of water contaminants

General

Iron (III) hydroxide is due to its chemical activity highly suitable for the binding of arsenate, phosphate or sulfide ions in aqueous media. The technical use of this universal adsorbent failed in the past because of its usually paste-like appearance. This typical occurrence of iron hydroxide makes it difficult to handle and prevents the use in simple filtration columns.
A patented process has succeeded, however, to manufacture an adsorbent based on iron hydroxide in granular form. Through the combination of crushing and sieving procedures a wide range of grain sizes can be produced. This gives access to a variety of new applications for the chemically highly reactive “Iron (III) hydroxide”

Operation

At first arsenate and phosphate ions in aqueous solution are adsorbed to the surface of FerroSorp® Plus. In a consecutive reaction the conversion to stable iron arsenate or iron phosphate takes place. The removal of sulfide ions is carried out by forming hardly soluble iron sulfide. Besides ordinary heavy metal ions, such as lead, copper and zinc other contaminants like antimony, molybdenum, cadmium, selenium, uranium, and fluoride are bound as well.
In addition a very non-specific binding of dissolved organic water pollutants by adsorption is possible.
The following chemical equations show the reaction of iron hydroxide with phosphate, arsenate, and hydrogen sulfide in a simplified scheme.

Applications

From the present perspective FerroSorp® Plus is suitable for the following applications:
- removal of arsenic(III)- and arsenic(V)-ions in potable water treatment
- cleaning of rainwater run-off, e.g. in retention soil filter systems
- binding of phosphate from rivers and lakes (water restoration)
- treatment of contaminated groundwater during the remediation of contaminated sites
- further phosphorus elimination in the clear water discharge of small sewage treatment plants and constructed wetlands
- pollutant retention in "reactive barriers"
- nutrient absorption in aquarium and garden pond maintenance
- treatment of heavy metal polluted industrial wastewater

Testing facility

For technical tests using granular iron hydroxide “FerroSorp® Plus” a testing facility with multiple adsorption columns and the possibility of an upstream turbidity removal is available.

Advantages at a glance

Brochure FerroSorp® Plus [68 KB]