Wednesday, April 14, 2010: 10:45 a.m.
Lawrence A/B (Westin Tabor Center, Denver)
Aquifer Storage and Recovery (ASR) is a proven application in the water resource management toolbox. After nearly 30 years of pilot and process testing, many successes have been documented; however, a few issues limit broader application of this powerful water resource management tool.
Water quality changes during ASR cycle testing. Geochemical reactions between recharge water and aquifer matrix affect water quality. Arsenic, molybdenum, and other transition metals can be released and transported during ASR cycle testing. Native radium and other U-series isotopes can be brought to the surface by mixing during recovery. Two alternatives exist to mitigate deleterious water-quality change: pre-treatment of recharge water, and operational strategies that lead to constituent attenuation. Cost-effective strategies that demonstrate these approaches are ongoing at ASR systems world-wide.
Disinfection of Recharge Water. Under current UIC regulations, total and fecal coliforms are proxies for the occurrence of enteric pathogens. However, Australian ASR studies document the systematic decline of coliform and pathogen abundance over time, in-situ, in aquifers. Is disinfection pretreatment necessary in potable and/or reclaimed water ASR systems, or could prolonged storage (months or years) be a cost-effective disinfection method? What aquifer conditions would be appropriate to demonstrate “natural attenuation” of coliforms and pathogens?
Reducing the carbon footprint of ASR. Cost-effective ASR requires a smaller carbon footprint. Reducing operation and maintenance (O&M) costs while maintaining reasonable regulatory compliance is critical to ASR feasibility. Utilizing native aquifer hydraulic characteristics will lead to lower energy consumption. For example, non-pumping recovery under artesian conditions, and optimizing pumping rates for maximum recharge and recovery flow in the aquifer are examples of process optimization that lead to lower O&M costs.
Water quality changes during ASR cycle testing. Geochemical reactions between recharge water and aquifer matrix affect water quality. Arsenic, molybdenum, and other transition metals can be released and transported during ASR cycle testing. Native radium and other U-series isotopes can be brought to the surface by mixing during recovery. Two alternatives exist to mitigate deleterious water-quality change: pre-treatment of recharge water, and operational strategies that lead to constituent attenuation. Cost-effective strategies that demonstrate these approaches are ongoing at ASR systems world-wide.
Disinfection of Recharge Water. Under current UIC regulations, total and fecal coliforms are proxies for the occurrence of enteric pathogens. However, Australian ASR studies document the systematic decline of coliform and pathogen abundance over time, in-situ, in aquifers. Is disinfection pretreatment necessary in potable and/or reclaimed water ASR systems, or could prolonged storage (months or years) be a cost-effective disinfection method? What aquifer conditions would be appropriate to demonstrate “natural attenuation” of coliforms and pathogens?
Reducing the carbon footprint of ASR. Cost-effective ASR requires a smaller carbon footprint. Reducing operation and maintenance (O&M) costs while maintaining reasonable regulatory compliance is critical to ASR feasibility. Utilizing native aquifer hydraulic characteristics will lead to lower energy consumption. For example, non-pumping recovery under artesian conditions, and optimizing pumping rates for maximum recharge and recovery flow in the aquifer are examples of process optimization that lead to lower O&M costs.
See more of: Aquifer Storage and Recovery: A Tool to Help Quench a Thirsty World?
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