Treatment of Groundwater Containing High Amounts of Manganese and Ammonia Nitrogen Using Activated Filtration Beds

Abstract

In the article the results of pilot investigations of a II stage filtration of grondwater containing high amounts of manganese and ammonia nitrogen (about 1,0 mg Mn /dm³ and 1,5 mg N-NH₄/dm³) are presented. Three types of filter media were used: mature quartz sand, “Metallex” and manganese ore. The efficiencies of manganese and ammonia nitrogen elimination in mature filter beds were similar and high, though in each case the length and course of the ripening process was different. The concentrations of manganese and ammonia nitrogen on the outflow from the filter were below 0,05 mg/dm³ and 0,50 mg/dm³, respectively. Some important differences between the filter beds were only observed during the first few weeks of performing the II stage filtration. The ripening period of the bed composed of quatz sand was the longest one and it took over 3 months (the other filter beds ripened faster). During this period of time, the grains of sand gradually got covered with an active layer of manganese compounds of typical black colour. After accomplishing the ripening process, the concentration of manganese on the outflow from the sand filter maintained at approximately 0,05 mg/dm³. It should be emphasized that even after accomplishing the ripening process, the elimination of manganese was still gradually improving. During the later investigations, when quartz sand working in the II stage filtration for over a year was used, the concentrations of manganese and ammonia nitrogen on the outflow from the filter were below 0,04 mg/dm³ and 0,2 mg N/dm³, respectively.