Enhanced adsorption of arsenic through the oxidative treatment of reduced aquifer solids

• Published in: Water research (Oxford) 2017-10, Vol.123, p.183-191
• Main Authors: Huling, Jenna R., Huling, Scott G., Ludwig, Ralph
• Format: Article
• Language: English
• Subjects: Adsorption; Arsenic; Arsenic - chemistry; Ground water; Groundwater; Hydrogen Peroxide; Oxidation; Oxidation-Reduction; Permanganate; Treatment; Water Pollutants, Chemical; Water Purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2017.06.064

Arsenic (As) contamination in drinking water is an epidemic in many areas of the world, especially Eastern Asian countries. Developing affordable and efficient procedures to remove arsenic from drinking water is critical to protect human health. In this study, the oxidation of aquifer solids through the use of sodium permanganate (NaMnO4), hydrogen peroxide (H2O2), and exposure to air, enhanced the adsorption of arsenic to the aquifer material resulting in treatment of the water. NaMnO4 was more effective than H2O2. NaMnO4 was tested at different loading rates (0.5, 1.5, 2.4, 3.4, and 4.9 g NaMnO4/kg aquifer material), and after 30 days contact time, arsenic removal ([As+3]INITIAL = 610 μg/L) was 77%, 88%, 93%, 95%, 97%, respectively, relative to un-oxidized aquifer material. Arsenic removal increased with increasing contact time (30, 60, 90 days) suggesting removal was not reversible under the conditions of these experiments. Oxidative treatment by exposing the aquifer solids to air for 68 days resulted in >99% removal of Arsenic ([As+3]INITIAL = 550 μg/L). Less arsenic removal (38.2%) was measured in the un-oxidized aquifer material. In-situ oxidation of aquifer materials using NaMnO4, or ex-situ oxidation of aquifer materials through exposure to air could be effective in the removal of arsenic in ground water and a potential treatment method to protect human health. [Display omitted] •In-situ and ex-situ ground water arsenic removal resulted from oxidative treatment.•NaMnO4, H2O2 oxidation of aquifer material (in-situ) enhanced arsenic adsorption.•NaMnO4-amended aquifer material immobilized more arsenic than H2O2.•Aquifer material exposed to air (ex-situ) resulted in >99% removal of arsenic.•Artificial oxidation of aquifer solids/soil reduces As concentrations in ground water.