Monash Infrastructure Institute, Department of Civil Engineering, Monash University, 8 Scenic Boulevard, Clayton 3800, VIC, Australia.
Monash Infrastructure Institute, Department of Civil Engineering, Monash University, 8 Scenic Boulevard, Clayton 3800, VIC, Australia.
Sci Total Environ. 2020 May 1;715:136680. doi: 10.1016/j.scitotenv.2020.136680. Epub 2020 Jan 15.
The use of stormwater biofilters (also known as bioretention systems and raingardens), in tropical and semi-arid areas is hindered by seasonal rainfall patterns which cause extended dry periods. These periods can result in plant die-off, long-term damage to system health and leaching of pollutants when stormwater inflows resume. Using an additional polluted water source during dry periods could minimise system stress and eliminate the need to irrigate biofilters with potable water during dry spells. As such, the presented laboratory study tested the seasonal operation of biofilters, by switching from stormwater treatment in wet months to greywater treatment in dry months. Forty-five single planted biofilter columns, incorporating sedges, grasses, understory ornamentals and vines, were subjected to four months of stormwater inflows, followed by three months of greywater inflows. We also investigated the impact of including a carbon source in the saturated zone on treatment performance. The results showed plant species selection to be critical for nitrogen and phosphorus removal, with consistently effective species such as Carex appressa and Canna x generalis able to maintain low outflow concentrations (e.g. total nitrogen of 0.2-0.3 mg/L and 0.3-0.6 mg/L, respectively) across both water sources. Low outflow phosphorus concentrations were associated with plant species that had high filterable reactive phosphorus removal across both water sources. Similarly, higher removal of ammonia and oxidised nitrogen was associated with lower overall nitrogen concentrations. In contrast, high removal of total suspended sediment (>94%), biochemical oxygen demand (>98%) and some heavy metals (e.g. lead >98% and copper >93%) was reported across all designs. The results suggest that with the careful selection of plant species, biofilters can be operated seasonally as a feasible and practical solution to maintaining system health during extended dry periods.
在热带和半干旱地区，利用雨水生物过滤器（也称为生物滞留系统和雨水花园）受到季节性降雨模式的阻碍，这些模式会导致延长的干旱期。这些时期可能导致植物死亡、系统健康的长期损害以及当雨水流入恢复时污染物的浸出。在干旱期间使用额外的污染水源可以最小化系统压力，并在干旱期间消除用饮用水灌溉生物过滤器的需要。因此，本实验室研究通过在湿月从雨水处理切换到干月的灰水处理来测试生物过滤器的季节性运行。四十五个单种植被生物过滤器柱，结合莎草、草、林下观赏植物和藤本植物，经历了四个月的雨水流入，然后是三个月的灰水流入。我们还研究了在饱和区包含碳源对处理性能的影响。结果表明，植物物种选择对于氮和磷的去除至关重要，像 Carex appressa 和 Canna x generalis 这样一直有效的物种能够在两种水源下保持低的出水浓度（例如总氮分别为 0.2-0.3mg/L 和 0.3-0.6mg/L）。低的出水磷浓度与在两种水源下具有高可过滤性活性磷去除的植物物种有关。同样，较高的氨和氧化氮去除与较低的总氮浓度有关。相比之下，所有设计均报告了总悬浮泥沙（>94%）、生化需氧量（>98%）和一些重金属（例如铅>98%和铜>93%）的高去除率。结果表明，通过仔细选择植物物种，生物过滤器可以季节性运行，作为在延长的干旱期维持系统健康的可行和实用的解决方案。
