Rubenstein School of Environment & Natural Resources, University of Vermont, Burlington, Vermont, USA.
Department of Civil and Environmental Engineering, Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, Wisconsin, USA.
J Environ Qual. 2023 Nov-Dec;52(6):1115-1126. doi: 10.1002/jeq2.20506. Epub 2023 Aug 25.
Bioretention cells, a type of green stormwater infrastructure, have been shown to reduce runoff volumes and remove a variety of pollutants. The ability of bioretention cells to remove nitrogen and phosphorus, however, is variable, and bioretention soil media can act as a net exporter of nutrients. This is concerning as excess loading of nitrogen and phosphorus can lead to eutrophication of surface waters, which green stormwater infrastructure is intended to ameliorate. Drinking water treatment residuals (DWTR), metal (hydr)oxide-rich by-products of the drinking water treatment process, have been studied as an amendment to bioretention soil media due to their high phosphorus sorption capacity. However, very few studies have specifically addressed the effects that DWTRs may have on nitrogen removal performance within bioretention cells. Here, we investigated the effects of DWTR amendment on nitrogen removal in bioretention cells treating stormwater in a roadside setting. We tested the capacity of three different DWTRs to either retain or leach dissolved inorganic nitrogen in the laboratory and also conducted a full-scale field experiment where DWTR-amended bioretention cells and experimental controls were monitored for influent and effluent nitrogen concentrations over two field seasons. We found that DWTRs alone exhibit some capacity to leach nitrate and ammonium, but when integrated into sand- and compost-based bioretention soil media, DWTRs have little to no effect on the removal of nitrogen in bioretention cells. These results suggest that DWTRs can be used in bioretention media for enhanced phosphorus retention without the risk of contributing to nitrogen export in bioretention effluent.
生物滞留池是一种绿色雨水基础设施，已被证明可以减少径流量并去除多种污染物。然而，生物滞留池去除氮和磷的能力是可变的，生物滞留土壤介质可以成为养分的净出口。这令人担忧，因为氮和磷的过度负荷会导致地表水富营养化，而绿色雨水基础设施旨在改善这种情况。饮用水处理残渣（DWTR）是饮用水处理过程中富含金属（氢）氧化物的副产品，由于其高磷吸附能力，已被研究作为生物滞留土壤介质的改良剂。然而，很少有研究专门探讨 DWTR 可能对生物滞留池内氮去除性能的影响。在这里，我们研究了 DWTR 改良对路边设置的雨水处理中生物滞留池内氮去除的影响。我们测试了三种不同 DWTR 在实验室中保留或浸出溶解无机氮的能力，还进行了一项现场实验，在两个野外季节中监测 DWTR 改良的生物滞留池和实验对照的进水和出水氮浓度。我们发现，DWTR 本身具有一定的浸出硝酸盐和铵盐的能力，但当整合到沙基和堆肥基生物滞留土壤介质中时，DWTR 对生物滞留池内氮的去除几乎没有影响。这些结果表明，DWTR 可用于生物滞留介质中以增强磷的保留，而不会增加生物滞留出水中氮的输出风险。
