Experimental study on pollutants removal from first flush by filtration through four filter medias

摘要

The purpose of this study was to investigate the effect of pollutants removal in first flush by filtration through four filter medias. The turbidity, SS, COD, TP and TN were surveyed. Four filter medias were selected from familiar and available materials, such as slag, geotextile, nylon net and wiry net. Experiments was conducted in a elaborate channel with raw water from a tank stored man-made early rainfall which was tap water mixed with soil according to the quality of early rainwater runoff in Beijing. As a result, it was showed that the 30cm thick slag was the most effective filter media, and its removal rate for turbidity, SS,COD, TN and TP was up to 89.2%,77.0%,18.4% ,6.4% and 13.5% respectively. The sequence of pollutants removal rate from high to low was 30cm thick slag, 20cm thick slag, 10cm thick slag, geotextile, combined nylon net and wiry net, wiry net and nylon net. The geotextile, which was applied extensively in construction field, had removal rate for turbidity,SS and COD was up to 79.4%,66.4% and 14.8% respectively. The result showed the geotextile could be one type of excellent material for pollutants removal of first flush and could be used in rainwater channel, gutter or gully.