Treatment of heavily contaminated storm water from an industrial site area by filtration through an adsorbent barrier with pine bark (Pinus Silvestris), polonite and active carbon in a comparison study

Abstract

Abstract: This study aims to evaluate a simple and robust filtration method for separation of heavy metals from storm water. The storm water, collected at a metals manufacturing site, is heavily contaminated with heavy metals. A first analysis showed exceptionally high concentrations of Zn, which was present in concentrations exceeding 200 mgL -1 . The basic idea is to filter the water as it flows out of the industry area through a passive barrier in the storm water well pipeline. Pine bark was in this study compared to two other materials; polonite and the conventional adsorbent active carbon. The forestry by-product pine bark (Pinus silvestris) consists of approximately 85-90 % dried and granulated pine bark and 10-15 % wood fibres. Polonite is a manufactured product originating from the cretaceous rock opoka. A laboratory experiment was set up, where the storm water from the industrial site was filtered through all three filter materials in a pilotscale model of the proposed installation. The filter cartridge model could be filled with approximately 2.2 L filter material. 3 L of the storm water was poured through the material through natural percolation, approximately 0.35 Lmin -1 . Treated and untreated storm water was analyzed for heavy metals, suspended solids, electric conductivity and pH. Active carbon showed the highest level of adsorption, with nearly 100 % of all metals adsorbing to the filter. However, significant concentrations of As was desorbed from the material into the filtered water. Pine bark retained 90 % of the metals, even the Zn which was present in high concentrations. Polonite could only adsorb 70 % of the heavy metals and released Cr from the material