Treatment of Seepage Water from a Tailings Pond of Uranium Mining: Column Tests with a Novei Schwertmannite Adsorbent

摘要

Based on biotechnologically synthesized schwertmannite (SHM) from iron and sulfate containing lignite mine water, the agglomerated, filter-stable adsorbent 'SHM-sorpP' was developed by com-pacting SHM in a briquette press (Peiffer et al, 2012; Janneck et al., 2014). As investigated by Fukushi et al. (2003), Regenspurg and Peiffer (2005), and Schroth and Parnell (2005), schwertmannite offers excellent adsorption properties towards arsenic.Building on several laboratory test regarding the suitability of the new adsorbent for the removal of arsenic from water (Peiffer et al. 2012), SHM-sorpP was tested in this study in comparison to the commercially available iron hydroxide adsorbents Ferrosorp~R Plus (HeGoBiotec GmbH) and GEH~R 104 (GEH Wasserchemie & Co KG) with regard to its suitability for the treatment of seepage water from an uranium tailings pond in column tests. The seepage water was characterized by high pH (8.7-8.9) and significant concentrations of arsenate, molybdate, and phosphate. For the tests, a water pretreatment was realized by decreasing its pH to 7 (pH 7 scenario) and pH 5 (pH 5 scenario) with a dosage of hydrochloric acid (33%), respectively.In the pH 7 scenario (columns with each of the three adsorbents) no molybdate could be adsorbed by Ferrosorp~RPlus, GEH~R104, and SHM-sorpP. In contrast, all adsorbents were able to immobilize more or less arsenate and phosphate with SHM-sorpP offering the most efficient adsorption. In the pH 5 scenario (columns with SHM-sorpP and Ferrosorp~R Plus each), SHM-sorpP again offered the better performance in the tests: in comparison to Ferrosorp~ Plus, about 30% more arsenate and phosphate as well as 100%) more molybdate could be adsorbed.