INTEGRATED PASSIVE TREATMENT TO REDUCE METAL AND NUTRIENT CONCENTRATIONS IN WATER’ by

This studyis part of a collaborativeeffortbetweenMontanaTechand AtlanticRichfield Companyto find solutions for treating metal-contaminated surface runoff from the surrounding city of Butte, Montana. The runoff flows into a storm drai% which transports the suspended and dissolved metals into nearby Silver Bow Creek, a tributary of the Clark Fork River. The study compared percent removal of metrds and nutrients by treatments of ( 1) undiluted storm drain water, through a gravel bed amended with cow manure, supporting cattails, (2) storm drain water combined with water from the local sewage treatment plant, through a gravel-only bed, and (3) the same combined-source water, through a gravel-only bed supporting cattails. Nutrients essential for supporting plants and microbial populations were supplied by both influent and manure in the first case, and by the combined-source influent in the second and third cases. The three treatment cells were 1.5 cubic meter, non-recycling, pilot-scale wetlands systems. Metal and nutrient percent removals were examined over residence times of 15, 10, and 5 days, Three metals were reported: cadmium, copper, and zinc. For cadmium, the combined-source treatments achieved percent removals from diluted concentrations which were similar to those achieved by the manure-amended treatment receiving the undiluted source. Percent removals of copper and zinc were greatest in the manure-amended treatment. Percent removal of nitrate was greatest in the cells containing cattails. Percent removal of phosphorous was greatest in the gravel-only cell supporting cattails. Additional