Pollutant treatment efficiencies through rainwater tank, recycled foamed glass and geofabrics

Abstract

ABSTRACT This study investigated the effectiveness of removing pollutants from roof-collected rainwater through rainwater tank, filtration using recycled foam glass and geofabrics using series of laboratory experiments. It is found that rainwater tank itself helps to remove some pollutants, especially total suspended solids (TSS). To test the efficiency of recycled foam glass as filter material, the material was used to filter rainwater collected from roof. It is found that through such filtration most of the pollutants’ concentrations in the rainwater drop by about 50%. Also, removal efficiency of a 30 cm filter media is about double compared to a filter media of 10 cm height. However, concentrations of Suspended Solids, Copper and Lead in the filtered samples were higher than the concentrations in the raw sample, which might be due to leaching of pollutants from filter media as it is found that higher the filter depth, higher the pollutants concentrations in the filtrate. To overcome these pollutants’ leaching, similar experiments conducted with geotextile layer at the bottom of the filter material revealed that through the use of geotextile layer with 30 cm filter media, significant reductions of pollutants are achievable including an 87% removal in number of Faecal Coliforms.