DETERMINATION OF LIGNOCELLULOSIC MATERIALS SORPTION POTENTIAL FOR STORMWATER CONTAMINANTS

Modified and unmodified lignocellulosic materials were examined in a laboratory study to determine the sorption capabilities for common stormwater pollutants under continuous flow conditions. The synthetic stormwater influent was composed of 7 polycyclic aromatic hydrocarbons (PAH); nutrients (nitrate and ortho-phosphate); and the heavy metals nickel (II) zinc (II) and cadmium. Influent was pumped through columns packed with 3 grams (dry) of lignocellulosic materials at a rate of 3 ml/m. The materials investigated in this study included wood pellets, Pine, Douglas Fir, Aspen, European Beech, and Western Red Cedar. Removal of PAHs was greater on the part of the European Beech shavings and Aspen fibers compared to processed wood pellets, with greater sorption capacity for higher molecular weight PAHs compared to the lighter molecular weight PAHs. Very little removal capacity was shown for the anions in all three materials except for nitrate. Aspen fibers showed a strong sorption capacity for nickel, removing 50%-70% in the initial stage of the experiment. Contamination by zinc was detected and cadmium was used in place of zinc in the following experiments. Further, it was studied if a slower flow rate (1.5 ml/m) may affect the removal process. These experiments, together with tests on a chemically modified (hydrolyzed) wood, are still in progress. The results from these tests will be discussed.