FerroSorp® AW

Filter granulate based on iron hydroxide for further phosphate removal for small waste water treatment systems 


Phosphate compounds in municipal waste water to promote the growth of algae in water bodies due to its fertilizing effect and therefore eutrophication. Waste water from properties that are not connected to public waste water treatment facilities have to be cleaned in a biologically-dependent, waste water treatment apparatus before they are allowed to be discharged into bodies of water or be drained. The approval criteria defined by the German Institute of Construction Technology (DIBt) for further phosphorus elimination (cleaning class “+P”) for small water treatment plants is c ≤ 2 mg P/l in the water outlet. Currently only very few decentralized small waste water treatment plants feature additional phosphorus elimination to ensure this concentration in domestic waste water.


Our product, FerroSorp® AW, can be used as an efficient, inexpensive solution for further phosphorus elimination in waste water treatment, and can easily be retrofitted. The use of FerroSorp® AW not only minimizes the entry of phosphorus into bodies of water, but also provides the possibility to recycle the phosphorus for agricultural purposes and thus closing the natural phosphorus cycle.


Figure 1: Principle – further phosphate elimination from municipal waste water in combination with phosphorus recycling

Dissolved phosphate ions in mechanically and biologically pre-treated waste water are absorbed onto the FerroSorp® AW surface and thus eliminated from the water. High absorption capacity can be maintained by a subsequent chemical regeneration of the filter granules. At the same time, the absorbed phosphorus can be recycled and reused as a fertilizer or secondary raw material for the fertilizer industry.


With FerroSorp® AW, phosphorus can be completely removed from the water outlet of small water treatment plants and thereby eliminate the water hazard it represents. Additionally, phosphate can be recycled and made available for agricultural purpose. The application of FerroSorp® AW presents the opportunity to conserve resources and protect the Environment.

The phosphorus absorption capacity of FerroSorp® AW depends on the waste water parameters and basic conditions of each individual treatment plant. For each specific design, the optimal operating conditions are derived after determining the procedural technical conditions.

Examples for applications

A particular advantage of the method suggested is that, regardless of the applied technology in the small water treatment plant (SBR-plant, activated sludge treatment, fixed bed system, MBR-plant, sprinkle filter plant, etc.) phosphate can be eliminated from the biologically treated water.



As it stands, FerroSorp® AW can be used advantageously in the following applications:

  • Further phosphate elimination in the outlet of small waste water treatment plants / systems
  • Waste water treatment plants of gas stations and road houses
  • Aquaristics, swimming and garden ponds
  • Rain water run-off from streets

Advantages at a glance

  • High cleaning performance at low cost
  • Easily retrofittable solution for further phosphorus elimination
  • No additional chemicals directly into waste water
  • No additional sludge production
  • Regeneration of filter granulate to maintain absorption capacity
  • Possibility to recover phosphorus and subsequent use as secondary raw material for the production of fertilizers
  • Easy and cost-effective disposal of spent absorbent by a return guarantee of the supplier