Department of Civil and Environmental Engineering, Chalmers University of Technology, Sven Hultins Gata 8, SE-41296, Goteborg, Sweden.
Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, BC, V6T 1Z4, Canada.
Environ Sci Pollut Res Int. 2017 Aug;24(23):19167-19180. doi: 10.1007/s11356-017-9508-1. Epub 2017 Jun 29.
Bioretention, also known as rain garden, allows stormwater to soak into the ground through a soil-based medium, leading to removal of particulate and dissolved pollutants and reduced peak flows. Although soil organic matter (SOM) is efficient at sorbing many pollutants, amending the bioretention medium with highly effective adsorbents has been proposed to optimize pollutant removal and extend bioretention lifetime. The aim of this research was to investigate whether soil amended with activated carbon produced from sewage sludge increases the efficiency to remove hydrophobic organic compounds frequently detected in stormwater, compared to non-amended soil. Three lab-scale columns (520 cm) were packed with soil (bulk density 1.22 g/cm); activated carbon (0.5% w/w) was added to two of the columns. During 28 days, synthetic stormwater-ultrapure water spiked with seven hydrophobic organic pollutants and dissolved organic matter in the form of humic acids-was passed through the column beds using upward flow (45 mm/h). Pollutant concentrations in effluent water (collected every 12 h) and polluted soils, as well as desorbed amounts of pollutants from soils were determined using GC-MS. Compared to SOM, the activated carbon exhibited a significantly higher adsorption capacity for tested pollutants. The amended soil was most efficient for removing moderately hydrophobic compounds (log K 4.0-4.4): as little as 0.5% (w/w), carbon addition may extend bioretention medium lifetime by approximately 10-20 years before saturation of these pollutants occurs. The column tests also indicated that released SOM sorb onto activated carbon, which may lead to early saturation of sorption sites on the carbon surface. The desorption test revealed that the pollutants are generally strongly sorbed to the soil particles, indicating low bioavailability and limited biodegradation.
生物滞留，也被称为雨水花园，允许雨水通过基于土壤的介质渗透到地下，从而去除颗粒状和溶解的污染物并减少峰值流量。尽管土壤有机质 (SOM) 能够有效地吸附许多污染物，但向生物滞留介质中添加高效吸附剂已被提议用于优化污染物去除并延长生物滞留寿命。本研究的目的是研究与未添加的土壤相比，用来自污水污泥的活性炭改良的土壤是否能提高去除雨水经常检测到的疏水性有机化合物的效率。三个实验室规模的（520 厘米）柱体用土壤（堆积密度 1.22 克/厘米）填充；其中两个柱体添加了活性炭（0.5%w/w）。在 28 天内，使用上向流（45 毫米/小时）通过柱床将含有七种疏水性有机污染物和腐殖酸形式的溶解有机物的合成雨水-超纯水通过柱床。使用 GC-MS 测定出水中（每隔 12 小时收集一次）和受污染土壤中的污染物浓度以及从土壤中解吸的污染物量。与 SOM 相比，活性炭对测试的污染物表现出明显更高的吸附能力。添加的土壤对于去除中等疏水性化合物（log K 4.0-4.4）最有效：添加量低至 0.5%（w/w），可能会使生物滞留介质的寿命延长约 10-20 年，直到这些污染物饱和为止。柱试验还表明，释放的 SOM 会吸附到活性炭上，这可能导致活性炭表面的吸附位点过早饱和。解吸试验表明，污染物通常会强烈吸附到土壤颗粒上，表明生物利用度低，生物降解有限。
