METHOD

TESTING OPERATIONS
The demonstration scale engineered wetland test unit operated intermittently during 1998, 1999, and 2000 and continuously from May 1, 2001 to April 2002. After reconstruction of the initial anaerobic bioreactor, completed in Jun2, 2002, the system has operated without interuption since. An extensive program of regular sampling was established. During 1999, 2000, 2001, samples were taken at seven points in the system and delivered to the Teck Cominco assay lab for ICP-MS assays. Testing was for metal concentrations (total and dissolved) for Zn, As, Cd, and Fe, as well as for NO3 and SO4. Other parameters measured included temperature, pH, and dissolved oxygen (D.O.). Weather data was collected as well for two years (hours of sunlight, evaporation pan measurements, rainfall accumulation) to determine evaporation dynamics.

PLANT METAL UPTAKE AND SEQUESTRATION
Plants were harvested and analyzed for metal content during the three summers of operations. During the first year (1999), only a few plants were assayed for aboveground metal content, but during 2000 and 2001 those plants that had initially shown either tolerance or sequestration ability were extensively sampled. Plants tested during 2000 and 2001 were: Spartina pectinata, Rheum rhaponticum, Epilobium grandifolia, Deschampsia caespitosa, Salix exigua, Helianthus annuus, Carex marteninsei, Tripsicum dactyloides, Juncus drumondii, Juncus mertensianus, Typha latifolia, and Calamagrostis canadensis.

MICROBIOLOGICAL SAMPLING AND TESTING
Microbiological samples were taken from the two anaerobic bioreactor cells by driving 2.5 cm PVC pipes into the cell. Four samples were taken from AB1 and AB2. Four water samples were taken from the downstream HSSF cells and holding pond. Four biosolids samples were taken from the surface of the substrate in AB1 and three from AB2.

Sulphate reducing bacteria were incubated in a modified Postgate medium C in 20 mL serum bottles. Preparation of the medium is described in Benner et al. (2000). Bacterial numbers were calculated from an MPN table.