Abstract: The aim was to assess over 2 years the treatment efficiencies of vertical-flow wetland filters containing macrophytes and granular media of different. adsorption capacities. Different concentrations of lead and copper sulfate (constant for 1 year each) were added to urban beck inflow water in order to simulate pretreated (pH adjustment assumed) mine wastewater. After 1 year of operation, the inflow concentrations for lead and copper were increased from 1.30 to 2.98 and from 0.98 to 1.93 mg/L, respectively. However, the metal mass load rates (mg/m(2)/d) were increased by a factor of approximately 4.9 for lead and 4.3 for copper. No breakthrough of metals was recorded. Lead and copper accumulated in the biomass of the litter zone and rhizomes of the macrophytes. Furthermore, microbiological activity decreased during the second year of operation. Bioindicators such as ciliated protozoa and zooplankton decreased sharply in numbers but diatoms increased. In conclusion, the use of macrophytes and, adsorption media did not significantly enhance the filtration of lead and copper. Particulate lead is removed by filtration processes including straining. Furthermore, some expensive and time-consuming water quality variables can be predicted with less expensive ones such as temperature in order to reduce sampling costs.

Abstract: The oxidation of sulfide minerals at an ore transfer location in Western Canada has resulted in widespread contamination of underlying soil and groundwater. The oxidation of sulfide minerals has released sulfate [SO4] and heavy metals including cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], and zinc [Zn] into the groundwater. A compost-based sulfate-reducing reactive wall was installed in the path of the plume in an attempt to reduce the potential impact of the heavy metals on a down-gradient marine inlet. Monitoring of the reactive wall over a 21-month period has shown that Cu concentrations decrease from over 4000 mug/L to less than 5 mug/L. Cadmium, Ni, Pb, and Zn concentrations also show similar decreases with treated concentrations generally being observed near or below detection limits.

Abstract: Brenda Mines, located 22 km Northwest of Peachland in British Columbia, Canada was an open pit copper-molybdenum mine which closed in 1990 after 20 years of operation. The primary concern in Brenda's tailings and waste rock drainage is molybdenum at a concentration of approximately 3 mg/L.. The mine drainage is alkaline and contains little or none of the typically problematic heavy metals. Given that the waters downstream are used for municipal water supply and some irrigation, a discharge limit of 0.25 mg/L molybdenum was imposed with specific water quality guidelines in the receiving creek. A. review of all existing and potential molybdenum removal methods was undertaken prior to mine closure. The chosen process is a two-step iron co-precipitation with clarification and sand filtration at a slightly acidic pH. A 4,000 usgpm (912 m(3)/h) treatment plant was constructed and commissioned in 1998, at a cost of $10.5M. The successful removal of molybdenum from the drainage water is explained with details on some design innovations and operational challenges encountered during plant start-up. Investigated sludge disposal options are discussed although the long term disposal scenario has not yet been finalised.