Groundwater often contains soluble ferrous and manganous compounds which, when getting in contact with air, oxidize and convert into insoluble compounds (oxides, hydroxides). These may disturb processes such as seepage by choking up infiltration wells, or interfere with other conditioning or treatment processes.
For the purification of groundwater, the natural oxidation process and the subsequent deposition are accelerated and preceded for further use. The groundwater to be treated is first intensively aerated in tubular reactors with the help of aeration compressors. The oxidation performance can be increased by adding potassium permanganate. Subsequently, the groundwater is passed through high-performance rapid filters and mechanically filtered clear. In some cases, chemical-catalytic processes also take place on the gravelly filter material, which supports the oxidation process, in particular the demanganization process. The water leaves the filter virtually free of iron and manganese.
The filter containers are monitored with the help of differential pressure gauges. With appropriate loading of oxidized and precipitated iron and manganese compounds, the backwashing is automatically initiated via a freely programmable process control. During the backwashing of a filter, the water passes through a second filter.
The filter backwashing is carried out with flushing air combined with flushing water, which is taken from the pure water circuit. The filter bed is broken open and whirled through by the flushing air. The separated solids are removed from the filter circuit with the backwashing water.
The solid-containing backwashing water is thickened using flocculating auxiliaries. The resulting sludge is dewatered in a chamber filter press and then disposed of properly.