EVALUATION OF THE PERFORMANCE AND SAFETY OF A PINE BARK FILTER FOR LANDFILL LEACHATE AND STORMWATER TREATMENT: TOXICITY TESTING AND CHEMICAL ANALYSIS

摘要

The industrial by-product pine bark has been used successfully as a low-cost sorbent for removing heavy metals from wastewaters such as stormwaters and landfill leachates. Although the water treatment efficiency of pine bark is high, one reported drawback with using the filter material for water treatment is the potential leaching of organic compounds, e.g. tannines and other polyphenols. This phenomenon is likely to be particularly pronounced during the initial start-up phase of filtration with unused pine bark. The results from preliminary serial leaching tests with the filter material, has shown that the toxicity of the pine bark leachates to Daphnia magna (48 hr) decreases after each successive round of leaching. The aim of this study was to further investigate the leaching properties and stability of pine bark filter. In this study, parallel serial batch leaching experiments were performed with either doubly deionised or U.S. EPA moderately hard reconstituted water as leachant to determine the duration and extent of the initial desorption of organic material, analysed as DOC (Dissolved Organic Carbon), from the filter material. To further investigate the changes in toxicity of the pine bark leachates from each successive round of leaching, a more extensive toxicity assessment was performed with an aquatic ecotoxicity test battery consisting of an acute luminescent bacteria test (ROTAS) and a genotoxicity test (the Umu assay using Salmonella typhimurium TA1535/pSK1002).