The City of Goodyear and the U.S. Bureau of Reclamation partnered to study wetlands treatment of reverse osmosis (RO) reject concentrate. RO concentrate includes elevated concentrations of contaminants that are removed during treatment of brackish water for potable water use. Contaminants include salts, metals, and nutrients typically at concentrations that exceed water quality standards. In inland areas, few alternatives for concentrate management exist. The water industry continues to seek innovative methods for concentrate disposal that are cost effective, provide a beneficial use, and are environmentally sustainable. One approach is a vertical flow wetland that uses organic media as the primary mechanism for removal of regulated constituents and salt-tolerant vegetation to provide a secondary removal mechanism, aesthetics and habitat. Results during the first year of operation of the pilot scale study indicate that arsenic concentrations were reduced from 30 to less than 10 micrograms per liter (ug/L), selenium concentrations were reduced from 20 to less than 1 ug/L, chromium from greater than 45 to less than 5 ug/L and nitrate-nitrogen concentrations were reduced from about 55 milligrams per liter (mg/L) to less than 1 mg/L. Total Dissolved Solids (TDS) concentration in the RO concentrate is about 8,000 mg/L and after wetland treatment the TDS of the treated concentrate increases to about 11,000 mg/L due to evapotranspiration. After wetland removal of regulated constituents, the treated concentrate must be blended with other water to reduce the TDS concentration to 3,000 mg/L for surface water discharge to the Gila River. This treatment scenario would provide an innovative in-land treatment for RO concentrate, allow integration of the treatment method into the community, provide public outreach opportunities, and provide a new water source to the Gila River to create new or support existing habitat.
This presentation is available to AMTA Members only.
- Mitchell Haws
- US Bureau of Reclamation
- AMTA/SWMOA Technology Transfer Workshop, Carefree, AZ
- AMTA/SWMOA Technology Transfer Workshop
- Wetland treatment of selenium in Reverse Osmosis reject concentrate, A concentrate management alternative to evaporation ponds, Inland disposal of Reverse Osmosis reject concentrate