Uwayezu Jean Noel, Ren Zhongfei, Sonnenschein Sarah, Leiviskä Tiina, Lejon Tore, van Hees Patrick, Karlsson Patrik, Kumpiene Jurate, Carabante Ivan
Waste Science and Technology, Luleå University of Technology, Luleå, Sweden.
Chemical Process Engineering, University of Oulu, Oulu, Finland.
Sci Total Environ. 2024 Jan 10;907:168137. doi: 10.1016/j.scitotenv.2023.168137. Epub 2023 Oct 26.
The current study evaluated a three-stage treatment to remediate PFAS-contaminated soil. The treatment consisted of soil washing, foam fractionation (FF), and electrochemical oxidation (EO). The possibility of replacing the third stage, i.e., EO, with an adsorption process was also assessed. The contamination in the studied soils was dominated by perfluorooctane sulfonate (PFOS), with a concentration of 760 and 19 μg kg in soil I and in soil II, accounting for 97 % and 70 % of all detected per-and polyfluoroalkyl substances (PFAS). Before applying a pilot treatment of soil, soil washing was performed on a laboratory scale, to evaluate the effect of soil particle size, initial pH and a liquid-to-soil ratio (L/S) on the leachability of PFAS. A pilot washing system generated soil leachate that was subsequently treated using FF and EO (or adsorption) and then reused for soil washing. The results indicated that the leaching of PFAS occurred easier in 0.063-1 mm particles than in the soil particles having a size below 0.063 mm. Both alkaline conditions and a continual replacement of the leaching solution increased the leachability of PFAS. The analysis using one-way ANOVA showed no statistical difference in means of PFOS washed out in laboratory and pilot scales. This allowed estimating twenty washing cycles using 120 L water to reach 95 % PFOS removal in 60 kg soil. The aeration process removed 95-99 % PFOS in every washing cycle. The EO and adsorption processes achieved similar results removing up to 97 % PFOS in concentrated soil leachate. The current study demonstrated a multi-stage treatment as an effective and cost-efficient method to permanently clean up PFAS-contaminated soil.
本研究评估了一种用于修复全氟辛烷磺酸（PFAS）污染土壤的三阶段处理方法。该处理方法包括土壤冲洗、泡沫分离（FF）和电化学氧化（EO）。同时还评估了用吸附过程替代第三阶段（即EO）的可能性。研究土壤中的污染物以全氟辛烷磺酸（PFOS）为主，土壤I和土壤II中PFOS的浓度分别为760μg/kg和19μg/kg，分别占所有检测到的全氟和多氟烷基物质（PFAS）的97%和70%。在进行土壤中试处理之前，先在实验室规模上进行土壤冲洗，以评估土壤粒径、初始pH值和液固比（L/S）对PFAS淋溶性的影响。一个中试冲洗系统产生的土壤渗滤液随后用FF和EO（或吸附）进行处理，然后再用于土壤冲洗。结果表明，PFAS在0.063 - 1mm颗粒中比在粒径小于0.063mm的土壤颗粒中更容易淋溶。碱性条件和不断更换淋洗液均增加了PFAS的淋溶性。使用单因素方差分析的结果表明，实验室规模和中试规模洗出的PFOS均值无统计学差异。由此可以估算出，使用120L水进行20次冲洗循环，可使60kg土壤中的PFOS去除率达到95%。曝气过程在每个冲洗循环中可去除95 - 99%的PFOS。EO和吸附过程在浓缩土壤渗滤液中去除PFOS的效果相似，最高可达97%。本研究证明了多阶段处理是一种有效且经济高效的方法，可永久清理受PFAS污染的土壤。
