Project Details

Description

SRPASU Cooperative Agreement JRP SRP/ASU Cooperative Agreement (2011-2012) SRP/ASU Cooperative Agreement FY2013 Groundwater in the service area contains naturally occurring levels of chromium, arsenic and selenium. Use of these groundwaters directly at SRP power plants (Santan and Kyrene), or when blended with surface waters, poses a challenge to meet discharge limits because as cooling water evaporates, the concentrations of the metals in the blowdown water increases. New, lower limits on these metals are being considered which necessitates consideration of how to remove the metals from blowdown water before discharge. Simultaneously, some forms of these metals pose challenges for potable water treatment plants (WTPs) served by SRP water when groundwater wells are pumped. While the WTPs on canals are capable of removing arsenic, less is known about their removal or transformation of chromium species especially in light of considerations to reduce the regulatory limits on some forms of chromium (specifically hexavalent chromium). The current Environmental Protection Agency (EPA) maximum contaminant level (MCL) is 0.1 mg/L for total chromium, but in 2010 the EPA decided to conduct additional monitoring of hexavalent chromium (Cr(VI)) and consider lower regulations based upon recent health studies. California has a 50 g/L standard and a 0.02 g/L public health goal for Cr(VI). Arizona has a 27 ppb Cr(VI) standard, but is considering decreasing this level if the EPA changes their regulations. Arizona has a regulatory discharge limit determined by the National Pollutant Discharge Elimination System (NPDES) of 11 ppb for Cr(VI) and 230 ppb for trivalent chromium (Cr(III)), but lower levels exist for aquifer protection in some cases. Cr(III) has a lower health risk than Cr(VI), but chlorine and other disinfectants readily oxidize Cr(III) to Cr(VI). Analytical techniques are available to speciate and quantify different chromium oxidation states. Cr(VI) is an anion that is more difficult to remove than Cr(III), which typically occurs as a cation that can be removed by ion exchange or coagulation. Chemical reduction of Cr(VI) to Cr(III) is possible using ferrous compounds2, and removal of both forms by commercially available media have been thoroughly investigated already. Among the best technologies for removing Cr(VI) is anion exchange3 for which highly selective resins are available. Cr(III) is also well removed by ion exchange resins (cationic)4. While the new EPA activities focus on filling Cr(VI) occurrence data, it is already evident that Cr(VI) occurs in groundwaters throughout Arizona which will likely be representative of much of the southwestern USA. Arsenic is also naturally occurring in Arizona, and can occur as H3AsO4, H2AsO4-, HAsO42-, or AsO43- in oyxygenated waters. Westerhoff has conducted numerous studies in Arizona on arsenic occurrence and treatment5-9, including a speciation study of As(V)/As(III) in SRP groundwaters. We concluded that the oxic environment in the local groundwater means that only As(V) is present. The drinking water limit for total arsenic decreased from 50 ppb to 10 ppb in 2006, and it is likely that the current NPDES permit levels for SRP could drop from the current 50 ppb to the 10 ppb level for aquifer protection. FY 15 SRP/ASU Cooperative Agreement FY 16 SRP/ASU Cooperative Agreement SRP (JRP) 98-153C MOD 43: Adding Blockchain IoT Platform for P2P Energy Transactions JRP (SRP) Admin F&A Funds for 2019-2020 Awarded Projects JRP (SRP) Admin F&A Funds for 2019-2020 Awarded Projects JRP (SRP) Admin F&A Funds for 2019-2020 Awarded Projects JRP (SRP) Admin F&A Funds for 2020-2021 Awarded Projects JRP (SRP): Project Management JRP (SRP) Admin F&A Funds for 2021-2022 Awarded Projects
StatusActive
Effective start/end date7/1/118/31/22

Funding

  • INDUSTRY: Domestic Company: $660,190.00

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