The city of Spokane has chosen five companies from around the U.S. and Canada to supply six small wastewater treatment units for use in a two-year, $7.7 million pilot project, says Dale Arnold, the citys director of wastewater management. Hayden, Idaho-based Blue Water Technologies Inc. will supply one of the treatment units at a cost of about $360,000. Companies in Oregon, North Carolina, Massachusetts, and British Columbia will provide the other units.


The overall $5.3 million worth of equipment will be used in a $2.4 million study to determine the best way to reduce the level of phosphorus in the citys treated waste water by 90 percent. Esvelt Environmental Engineering LLC, of Spokane, will conduct the study once the equipment is installed, Arnold says.


The city is required by the Washington state Department of Ecology to get the level of phosphorus in its waste-water discharge down to 10 parts per billion from its current level of 700 to 1,000 parts per billion, Arnold says.


The pilot study will pair up the six units into three ultra-filtration systems, each in a scaled-down size, but capable of processing a half-million to a million gallons of effluent per day, Arnold says. The systems will add chemicals and utilize increased filtration to reduce the phosphorus levels further.


When the project is finished, the city will choose one of the new systems and install new equipment that can handle up to 55 million gallons per day. The system currently processes about 39 million gallons of effluent daily.


Arnold says he expects to reduce phosphorus levels to 50 parts per billion with the new equipment. The city will make up the difference to reach an equivalent of the 10 parts per billion requirement by using some of the treated wastewater for irrigation, possibly at golf courses, and finding other locations than the river to deposit some of it.


Arnold says the city will use the six treatment units after the study is concluded. He says the department likely will install them at outlying areas, perhaps near a golf course, where its reusing wastewater, which should reduce some of the load on the main treatment plant. The reused wastewater would be suitable for irrigation, but not for human consumption, Arnold says.


The purchase of the units is not going to waste. We will use them for a study, but then continue to use them, he says.


The six treatment units will be installed at the waste-water treatment plant on a 100-foot by 200-foot asphalt pad, says Lars Hendron, the citys principal waste-water management engineer.


The companies supplying the treatment units have included in their bids the cost of setup, including awnings to protect the equipment from the weather and training the study team to operate the units, Hendron says. The city will provide and install the pipe needed to route some of the untreated wastewater to the units.


Hendron says he expects that the study will begin by the first part of 2008. The first year of the study will be spent collecting data and the second year will be spent developing a report, Hendron says. He adds that the pilot units will remain in operation throughout the two-year study.


Contact Jeanne Gustafson at (509) 344-1264 or via e-mail at [email protected].