Spokane River dischargers face restrictive phosphorus discharge limits that are technically challenging. A tertiary phosphorus removal pilot at the wastewater treatment plant was conducted between June and October 2006. Technologies from four different manufacturers were tested on their
ability to reliably produce effluent total phosphorus (TP) concentrations of less than 50 μg/L and less then 10 μg/L. The demonstration pilot showed that effluent total phosphorus concentration of less than 50 μg/L can be produced by at least two of the tested technologies, Blue Water
Technologies Blue Pro (DSBP) and Siemens Trident® HS-1 (THS-1). While not fully demonstrated, GE (Zenon) ultrafiltration (ZW-500) and Parkson Incorporation Dual Sand (DSD2) would also likely be able to meet 50 μg/L. None of them showed ability to meet a 10 μg/L TP limit.
While there were a number of days with 10 μg/L or less, they were few and far between.
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