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STORMWATER FILTRATION USING MULCH AND JUTE
Citation:
Wojtenko**, I, A. B. Ray*, AND R Field*. STORMWATER FILTRATION USING MULCH AND JUTE. Presented at 2001 Pennsylvania Stormwater Management Symposium, Villanova U, Pennsylvania, 10/17-18/2001.
Description:
This study evaluated the feasibility of using readily available, low-cost natural filter naterials for stormwater (SW) treatment. Generic (hardwood) mulch and processed jute fiber were evaluated for the removal of metallic and organic pollutants from urban SW runoff samples collected at a "hot-spot" (commercial parking lot) site in NJ. The retention and release behavior of several representative pollutants (5 organic compounds 7 5 metals) commonly found in SW were evaluated for different filter materials. A specially constructed bench-scale filtration apparatus was used to simultaneously assess the performance of up to 10 different media/medium. SW flowrates through the individual filter columns as well as the sorption capacity of each filter medium were studied under a wide variety of conditions. The advantages of combining mulch or jute with sand (in a 50/50 ratio) to improve the hydraulic properties (filter flux) and the removal and cumulative capacities of the filter media for a specific pollutant were evaluated. The author's previous study showed that the pollutant removal efficiencies of the filtration media depended on their physical characteristics. e.g., particle size and medium-to-sand ratios. Removals as high as 100% of copper and >90% of benzo(a)pyrene were observed for all the media. In this paper sorption capacities of filter media are discussed for mixtures of 10 pollutants, 5 organics and 5 metals. Both jute and generic mulch medium were used with unaltered particle size and in the mixtures of 50% medium to 50% sand. The SW samples used contained mixtures of the 10 pollutants at several concentrations. Results show that both jute/sand and mulch/sand systems can remove >99% of all 5 organic pollutants. On the basis of sorption capacity (expressed in ug/g of dry medium) jute was found to have a much higher capacity (215 ug/g) when compared to mulch (22 ug/g) for all of the organic compounds Generic mulch was found to be more efficient for metal sorption than jute. Both materials were found to be more efficient in removing organic compounds than metals. In all cases, pollutants were found to be highly sorbed by both media, and once sorbed, they were not dislodged by washing the media with distilled water. Both mulch and jute appear to be suitable filter materials for complete removal of organic compounds and partial removal of metals commonly found in urban SW runoff. Additional investigations are necessary to evaluate the feasibility of using these two filter media for the treatment of SW runoff. Practical disposal procedures for the used media also need to be developed.