The iron and manganese removal systems designed by Hidrotec are based on oxidation, precipitation and retention in filter media.
The iron and/or manganese are firstly oxidated by aeration, to later go through a filtration stage of pyrolusite and sand in different proportions, depending on the iron and manganese load in the water to be treated.
Pyrolusite is a manganese dioxide (MnO2) with a concentration of 75-80%. The presence of oxygen in the product supports the removal of Fe and Mn catalytically.
In general, pyrolusite is added to the surface of sand filters. Due to the high density of the product, greater than the filtering sand, it penetrates into the bed, settling after approximately 3-4 washes in a range between 500-700 mm deep. This operation stratifies the bed into 3 different layers:
– a first layer of filtering sand,
– a second layer of pyrolusite,
– a third layer of filtering sand.
The first layer (sand) has the function of retaining the particles, where part of the Fe/Mn is eliminated.
The second layer (pyrolusite), free from particle contamination, remains active to carry out the catalytic action and thus retain the Fe/Mn.
The third layer (sand) guarantees the final polishing of the effluent.
Pyrolusite does not need to be regenerated due to its high purity and catalytic function.