Reactive filters for removal of dissolved metals in highway runoff

Abstract

A pilot-scale system consisting of presedimentation and a saturated down-flow reactive bed filter was used for cleaning highway runoff. Blast furnace slag (BFS) and Polonite were selected as filter materials. A total suspended solids (TSSs) removal of over 99% was achieved. High removal performance was observed for dissolved Mn, Ni, Co, and Cu. In contrast Al was released after filtration. Metals were retained in the upper layer of the bed filters while a desorption was suggested to take place in the downward layers. This was probably attributed to the elevated salt levels during winter and the intermittent operation.