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Arsenic Treatment The rest of the story

Arsenic Treatment The rest of the story. Presented to:. Texas Commission on Environmental Quality October 25, 2005. Russell Fisher Turnstone Services The Woodlands, Texas (281) 419-0747. The Commercial Perspective. Locate prospects – anticipate the unmet need

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Arsenic Treatment The rest of the story

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  1. Arsenic TreatmentThe rest of the story Presented to: Texas Commission on Environmental Quality October 25, 2005 Russell Fisher Turnstone Services The Woodlands, Texas (281) 419-0747

  2. The Commercial Perspective • Locate prospects – anticipate the unmet need • Qualify Prospects – gather data to understand need • Propose Solution - Satisfy customer’s need Turnstone Services

  3. The Need - Arsenic Treatment Objectives Achieve compliance Conserve the water resource Define the Need – Gather Information Aquifer characteristics Water Quality Data - TCEQ Usage information - PWS Develop Arsenic Treatment Strategy Associated regulatory issues Technology Constraints Unanticipated Consequences Turnstone Services

  4. Texas Groundwater is a Dynamic System • Sandstone Aquifers – highly variable over short dist • Intermittent Recharge – year to year rainfall variance • Regional climate variation – fluctuating water levels • Coastal faulting and subsidence • Geochemistry - the rock/water system Turnstone Services

  5. Understanding the Environment Indicator Species TDS - may require lowering of salt content pH - activity of the hydrogen ion Eh – electrode potential, activity of the electron Ca/Mg – hardness, scale forming pH sensitive Cl- – major contributor to TDS HCO3- – contributes to TDS, limits F trmt Turnstone Services

  6. The lesser know elements of water chemistry Turnstone Services

  7. Common Redox Species In Ground Water Oxidized Sand Reduced Sand Turnstone Services

  8. Groundwater Redox Front O2 H2O Fe2O3 UO2+2 MoS2 HAsO4- As2O3 H3AsO3 As2S3 MoO4-2 UO2 FeS2 Turnstone Services

  9. Importance of redox potential Redox state often dictates solubility Fe(+III) insoluble, Fe(+II) low to moderate solubility U(+IV) insoluble, U(+VI) highly soluble Redox affects acid-base behavior, i.e. charge H3AsO4 mild acid, H3AsO3 weak acid HNO3 strong acid, HNO2 weak acid Redox reactions affect pH Ionization of weak acids: HCO3-1, H4SiO4 Turnstone Services

  10. Typical Treatment Strategies Rule #1: Match the Solution to the Problem Turnstone Services

  11. Summary • Understand geological setting – aquifer type, mineralogy • Analyze water sample for less known species • Interpret water analysis in context of aquifer geochemistry • Apply technologies that best address the problem Turnstone Services

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