Key Laboratory of Northwest Water Resources, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
Environ Sci Pollut Res Int. 2015 Sep;22(17):12982-91. doi: 10.1007/s11356-015-4573-9. Epub 2015 Apr 29.
The choice of substrates with high adsorption capacity, yet readily available and economical is vital for sustainable pollutants removal in constructed wetlands (CWs). Two identical large-scale demonstration horizontal subsurface flow (HSSF) CWs (surface area, 340 m(2); depth, 0.6 m; HLR, 0.2 m/day) with gravel or slag substrates were evaluated for their potential use in remediating polluted urban river water in the prevailing climate of northwest China. Batch experiments to elucidate phosphorus adsorption mechanisms indicated a higher adsorption capacity of slag (3.15 g/kg) than gravel (0.81 g/kg), whereby circa 20 % more total phosphorus (TP) removal was recorded in HSSF-slag than HSSF-gravel. TP removal occurred predominantly via CaO-slag dissolution followed by Ca phosphate precipitation. Moreover, average removals of chemical oxygen demand and biochemical oxygen demand were approximately 10 % higher in HSSF-slag than HSSF-gravel. Nevertheless, TP adsorption by slag seemed to get quickly saturated over the monitoring period, and the removal efficiency of the HSSF-slag approached that of the HSSF-gravel after 1-year continuous operation. In contrast, the two CWs achieved similar nitrogen removal during the 2-year monitoring period. Findings also indicated that gravel provided better support for the development of other wetland components such as biomass, whereby the biomass production and the amount of total nitrogen (TN; 43.1-59.0 g/m(2)) and TP (4.15-5.75 g/m(2)) assimilated by local Phragmites australis in HSSF-gravel were higher than that in HSSF-slag (41.2-52.0 g/m(2) and 3.96-4.07 g/m(2), respectively). Overall, comparable pollutant removal rates could be achieved in large-scale HSSF CWs with either gravel or slag as substrate and provide a possible solution for polluted urban river remediation in northern China.
具有高吸附能力、易于获得且经济实惠的基质的选择对于构建湿地 (CWs) 中可持续的污染物去除至关重要。两个相同的大型水平潜流 (HSSF) CW （表面积 340m²；深度 0.6m；HLR 0.2m/d），砾石或矿渣基质，用于评估其在中国西北盛行气候下修复受污染城市河水的潜力。阐明磷吸附机制的批量实验表明，矿渣的吸附能力更高（3.15g/kg），比砾石（0.81g/kg）高，在 HSSF-矿渣中记录的总磷 (TP) 去除量约高出 20%。TP 去除主要通过 CaO-矿渣溶解随后发生 Ca 磷酸盐沉淀。此外，HSSF-矿渣的化学需氧量和生化需氧量的平均去除率比 HSSF-砾石高约 10%。然而，矿渣对 TP 的吸附似乎在监测期间迅速饱和，并且在 1 年连续运行后，HSSF-矿渣的去除效率接近 HSSF-砾石。相比之下，两个 CW 在 2 年监测期间实现了相似的氮去除。研究结果还表明，砾石为生物量等其他湿地组分的发展提供了更好的支持，其中本地芦苇在 HSSF-砾石中的生物量产生和总氮 (TN; 43.1-59.0g/m²) 和 TP (4.15-5.75g/m²) 的同化量高于 HSSF-矿渣中的同化量（41.2-52.0g/m²和 3.96-4.07g/m²）。总的来说，在大型 HSSF CW 中，使用砾石或矿渣作为基质可以实现相当的污染物去除率，为中国北方受污染城市河流的修复提供了一种可能的解决方案。
