De-ironing and De-manganisation filters ERF / ERF-FE are available from Waterflow Control .


Dissolved iron and/or manganese compounds are removed from water by oxidation. Oxidation causes these compounds to become insoluble in water, precipitate and allows them to be filtered out.

In order to accelerate the filtration and separation process, a special biological filter material with a catalytic effect is used in the units. This guarantees safe de-ironing and/or de-manganisation to comply with the required guidelines.

The de-ironing and -manganisation is divided into 4 steps:

1) Oxygen concentration

The process required for oxygen enrichment must be selected according to the composition of raw water.

The processes described below can be combined for critical raw material qualities.

In process 1, the oxygen in the water is sufficient to oxidize the iron or manganese ions.

In process 2, an oxidizing agent (potassium permanganate) must be added to the untreated water. For this, a metering station and a contact water meter with a pulse interval of one litre are required.

In process 3, a small quantity of air is added to the untreated water upstream of the filter unit to oxidize the iron and manganese. The air is added using an oil-free compressed air unit or an external snifting valve (if a reciprocating pump is used).

2) Oxidation process

The filter material acts as a catalyst for oxidation of the iron and manganese. The catalyst shortens the reaction time and minimises the residual content of iron and manganese.

3) Filtration

The grain size selected guarantees good filtration and thus the maximum removal of the precipitated iron of manganese from the water. If the process is planned and run correctly, treated water qualities contain less than 0.1mg/l of iron and 0.05mg/l of manganese. However, in some cases, a run-in time of several days to several weeks is necessary.

4) Backwashing

The filter must be backwashed weekly to flush out the iron or manganese compounds. The flushing process is carried out automatically time controlled.