PERFORMANCE OF SLOW FILTERS WITH FILTER MEDIA MADE OF MIXTURES OF SAND AND SUSTAINABLE MATERIALS

Abstract

Slow filters are easy to build, operate and maintain, making them suitable for water treatment also in small communities. Although the filter media commonly used is sand, studies suggest its full or partial replacement by unconventional materials, as long as it maintains efficiency in water treatment. Thus, the objective of this work was to verify the efficiency of slow filters using sustainable materials coconut fibers and ceramic residue mixed with sand as a filter medium. For this, three slow filters with different filter media were set up on a laboratory scale, they are: sand mixed with ceramic residue (Filter 1), sand mixed with coconut fibers (Filter 2), and conventional sand filter (Filter 3). The filters operated with a downward flow at a filtration rate of 3 m³/m².d (± 10%) continuously, fed with groundwater with the addition of WTP sludge. Raw water and water treated by filters were analyzed according to the quality standards of current legislation. The filters were also compared with each other in terms of efficiency, to verify which one presented the best performance in the treatment. Although the three models of filters analyzed had similar performances and brought benefits to the treatment of water contaminated with total and thermotolerant coliforms, Filter 1 showed greater efficiency in removing the physical-chemical parameters turbidity and apparent color, Filter 2 showed greater efficiency only in removing of thermotolerant coliforms and Filter 3 in the removal of total dissolved solids. Therefore, in cases where ceramic residue or coconut fiber is available, it is suggested that these materials are mixed with sand for better performance of the filter media.