Abstract：
Dual upflow reactive filtration by a slowly moving sand bed with continuously renewed, hydrous ferric oxide-coated sand is used for removing polluting substances and for meeting the ultralow 0.05 mg/l total phosphorus discharge permit limits at a 1.2 million liters per day (0.32 million gallons per day) water resource recovery facility in Plummer, Idaho, in the United States. A life cycle assessment (LCA) of this reactive filtration installation was carried out to assess the environmental hotspots in the system and analyze alternative system configurations with a focus on CO2 equivalent (CO2 e) global warming potential, freshwater and marine eutrophication, and mineral resource scarcity. \"What if\" scenarios with alternative inputs for the energy, metal salts, and air compressor optimization show trade-offs between the impact categories. Key results that show a comparative reduction of global warming potential include the use of Fe versus Al metal salts, the use of renewable energy, and the energy efficiency benefit of optimizing process inputs, such as compressor air pressure, to match operational demand. The LCA shows a 2 × 10-2 kg CO2 e footprint per cubic meter of water, with 47% from housing concrete, and an overall freshwater eutrophication impact reduced by 99% versus no treatment. The use of renewable hydropower energy at this site isolates construction concrete as a target for lowering the CO2 e footprint. PRACTITIONER POINTS: The main LCA eco-impact hotspots in this dual reactive filtration tertiary treatment are construction concrete and the ferric sulfate used. Iron salts show smaller impact in global warming, freshwater eutrophication, and mineral resource scarcity than \"what if scenario\" aluminum salts. The energy mix for this site is predominantly hydropower; other energy mix \"what if\" scenarios show larger impacts. Operational energy efficiency and thermodynamic analysis show that fine tuning the air compressor helps reduce carbon footprint and energy use. LCA shows a favorable 2 x 10-2 kg CO2e/m3 water impact with 99% reduction of freshwater eutrophication potential versus no treatment.
摘要：
通过缓慢移动的砂床进行双上流反应过滤，并不断更新，含水氧化铁涂层的沙子用于去除污染物质，并在Plummer的每天120万升（每天32万加仑）水资源回收设施中达到超低0.05mg/l的总磷排放许可限值，爱达荷州,在美国。对该反应性过滤装置进行了生命周期评估（LCA），以评估系统中的环境热点并分析替代系统配置，重点是CO2当量（CO2e）全球变暖潜力。淡水和海洋富营养化，和矿产资源稀缺。“如果”具有替代能量输入的场景，金属盐,和空气压缩机优化显示了影响类别之间的权衡。显示全球变暖潜力相对降低的关键结果包括使用Fe与Al金属盐，使用可再生能源，以及优化过程输入的能效效益，如压缩机空气压力，以满足运营需求。LCA显示每立方米水2×10-2千克二氧化碳足迹，47%来自房屋混凝土，与不处理相比，总体淡水富营养化影响减少了99%。在该地点使用可再生水力发电将建筑混凝土隔离为降低CO2e足迹的目标。实践要点：这种双重反应过滤三级处理的主要LCA生态影响热点是建筑混凝土和使用的硫酸铁。铁盐对全球变暖的影响较小，淡水富营养化，和矿产资源稀缺性比“如果情景”铝盐。该站点的能源组合主要是水力发电；其他能源组合“如果”情景显示出更大的影响。运行能效和热力学分析表明，微调空气压缩机有助于减少碳足迹和能源使用。LCA显示出有利的2x10-2kgCO2e/m3水影响，与未处理相比，淡水富营养化潜力降低了99％。
