Runoff treatment with aspen wood

Runoff from roadways and urban areas is often contaminated with heavy metals such as zinc and copper. The use of aspen wood (Populus tremula) was investigated as a potential sorbentfor these metal contaminated runoff waters. The objective was to design an alternative runoff treatment technology based on a renewable resource, i.e. wood. Laboratory isotherms and column experiments were conducted in order to investigate the sorption and desorption of dissolved copper and zinc to and from aspen wood fibers. Sorption ofCu(II) and Zn(II) followed non-linear Freundlich isotherms. The aspen wood-water partition coefficient values revealed that Cu(II) had a greater tendency to sorb to the aspen wood than Zn(II). The column experiments indicated that, at least initially, both metals were being rapidly sorbed. During later stages of the sorption experiments, slower, but steady transport of the metal ions into the wood fibers appeared to be the dominating removal mechanism. Desorption of copper with E-pure water was faster than zinc, but the total amount of metal mass released from the wood was small in both cases, i.e., only 2% to 4% of the amount sorbed. Although initial dissolved metal removal data from an ongoing field test is inconclusive, it was shown that a proto-type wood filter and a viable runoff treatment technology can be build around wood-based filter