Rehabilitation of the filters: Effects of the works

Sand filters successfully remove iron, manganese and ammonia from water, which were contained, before filtration, in concentrations higher than those permitted by the Regulation on the hygienic quality of drinking water. After the filter field is rehabilitated, it takes time and appropriate conditions for the sand filling to be coated with a naturally formed layer of MnO2 and a biofilm containing microorganisms that contribute to the removal of iron and manganese, or ammonia. The study analyzes the effects of the works and the time required to achieve satisfactory filtration efficiency again.