An intermittently operated biochar filter to remove chemical contaminants from drinking water

Abstract

A biochar filter, in conjunction with a biosand filter, was used to remove environmentally relevant concentrations of synthetic organic chemical such as atrazine, anthracene, naphthalene and phenanthrene from creek water over a period of 36 days. The biochar filter achieved complete removal of anthracene and phenanthrene, and significant removal of atrazine and naphthalene at the beginning of the experiment. Atrazine removal was observed to be dependent on pause period/contact time (i.e., contact time between atrazine and the biochar in the filter) and declined over time. Longer pause period/contact time resulted in better removal of atrazine, though the same effect of contact time was not observed for anthracene, phenanthrene or naphthalene. Variation in the removal of atrazine along the length of the filter column was observed and atrazine removal for water samples collected near the top of the filter column was found to be the lowest. The possible desorption of the chemicals from the biochar media was investigated, results suggested possible leaching of atrazine from the biochar. Leaching of anthracene, naphthalene and phenanthrene was not observed. The biochar filter was shown to be a promising technology to remove synthetic organic compounds from drinking water and can be used in conjunction with a biosand filter for contaminant removal.