TECHNOLOGY EVALUATION FOR WATERBORNE MERCURY REMOVAL AT THE Y12 NATIONAL SECURITY COMPLEX

摘要: The Hg-contaminated processing water produced at Y-12 facility is discharged through the storm drain system, merged Outfall 200, and then to EFPC. Most of baseflow mercury 200 arises from a small number short sections drain. This report discusses waterborne treatment technologies decrease loading surface EFPC NSC. We reviewed current available Hg based on specific conditions identified two possible options: SnCl2 reduction coupled with air stripping (SnCl2/air stripping) sorption. ORNL 2008 2009 field studies suggested that SnCl2/air has capability remove efficiency higher than 90% 200. To achieve this goal, dechlorination (i.e., removing residual chlorine water) using dechlorinating agents such as thiosulfate be performed before reduction. It unclear whether or not can reduce concentration ~1000 ng/L 51 full-scale operation. Therefore, pilot test logical step design answer questions removal efficiency, selection agents, so on. major advantages SnCl2/airmore » system are: (1) expected low cost high flow (e.g., 200); (2) production minimum secondary waste. However, there are many environmental uncertainties associated technology by introducing tin ecosystem, for example methylation causing abiotic methylation, which should addressed implementation. Mercury adsorption granular activated carbon (GAC) proven treating Y-12. ONRL 2010 lab sorption suggest thiol-based resins hold promise combine GAC form more cost-effective system. goal (flow rate: 1300 gpm), single will request very large reaction vessels much (assuming it goal). depends goal. If ng/L, significantly reduced while remain same. In addition, resin may further cost. Treating source area rate 40 gpm) another option reliability, no uncertainties. disadvantages include produces amount wastes. Based information evaluated in report, we recommend pilot-scale process carried out implementation address all engineering risk questions. also continuing sorbent optimize efficient enough implementation.« less