16S rRNA gene amplicon sequencing data of rapid sand filters of various ages

Aeration followed by rapid sand filtration is a widely used technology in drinking water production for removal of iron, manganese and ammonium from anoxic groundwaters. Frequently it is observed that the filter efficiency decreases after several years of operation. When the filters are replaced it can take several months before removal of manganese and ammonium begins. While it is well known that both chemical and microbiological removal processes contribute to removal of these compounds, the chemical and biological interactions are not well understood, especially as the filters age. A better understanding of the processes occurring during the ripening phase and the subsequent ageing phase can help to improve the performance of filters.