Citation:

Neil, C., J. Yang, D. Schupp, AND Y. Jun. Water Chemistry Impacts on Arsenic Mobilization from Arsenopyrite Dissolution and Secondary Mineral Precipitation: Implications for Managed Aquifer Recharge. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 48(8):4395-4405, (2014).

Impact/Purpose:

Communicate to the science and technical community of EPA research results on aquifer storage and recharge impacts on groundwater quality

Description:

Managed Aquifer Recharge (MAR) is one water reuse technique with the potential to meet growing water demands. However, MAR sites have encountered arsenic remobilization resulting from recharge operations. To combat this challenge, it is important to identify the mechanism of arsenic remobilization during MAR. In this bench-scale study, arsenic remobilization from arsenopyrite (FeAsS) was characterized for conditions relevant to MAR operations. Experimentally determined activation energies for arsenic remobilization from FeAsS under aerobic conditions were 36.87 ± 2.27 kJ/mol for 10 mM sodium chloride, and 40.81 ± 3.52 kJ/mol for 10 mM sodium nitrate, and 43.63 ± 4.98 kJ/mol for secondary effluent from a wastewater treatment plant. In addition, sodium chloride had higher arsenic remobilization under aerobic conditions. Interestingly, secondary mineral precipitation varied between systems and further affected arsenic remobilization. For example, the wastewater system inhibited precipitation, while faster phase transformation of iron(III) (hydr)oxide precipitates was observed in the sodium chloride system, resulting in hematite formation after 7 days in this system only. The transformation would result in less available surface area for arsenic attenuation. Together, these new observations and calculated activation energies can be used to model arsenic reactive transport during MAR and develop scenarios to minimize arsenic release.

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