Constructed wetlands are a nature-based engineering solution enabling polishing of septic tank effluents at low-cost. However to date, the influence of planting on treatment efficiency remains little understood. Here we report a case study evaluating the performance of two near-identical Horizontal Sub-Surface Flow Constructed Wetlands (HSSF-CW) deployed at a school in southern India. The HSSF-CWs were of similar size and construction with the exception that one system was planted (Canna indica) whilst the other was operated without plants. Both systems were operated at similar hydraulic loading rate (HLR) and hydraulic retention time (HRT) of 84 mm day⁻¹ and 3.7 days, respectively to treat the effluent from septic tanks. The systems were monitored fortnightly for one year and the performance kinetics, nutrient and organics removal efficiencies were evaluated. Significant reduction in biochemical oxygen demand (BOD₅) and chemical oxygen demand (COD) (p < 0.05) were observed in both systems with BOD₅ removal efficiency of 67% and 61% in the planted and unplanted systems, respectively. Whilst the effluent from both systems met the environmental discharge standards set by Central Pollution Control Board (CPCB), India, the total phosphorus (TP) and total suspended solids (TSS) removal in the unplanted system were significantly greater than in the planted system. The first-order decay rate constants (K) obtained for TN (K_TN) and BOD₅ (K_BOD5) in the planted system (0.16 day⁻¹ and 0.30 day⁻¹) were higher than in the unplanted system (0.09 day⁻¹ and 0.27 day⁻¹). Greater R² values obtained for the planted system (~ 0.90) suggests applicability of a first-order decay model to assess contaminant degradation. Plants contributed to 7% (0.3 g/m²/day) BOD₅, 18% (1.9 g/m²/day) COD and 5% (0.09 g/m²/day) TN load removal. Our data demonstrates that planting is effective in improving treatment efficiency in constructed wetlands, and whilst the improvement is marginal here, it is noted that a rust infection could have limited effectiveness of the plants in this case.

人工湿地是基于自然的工程解决方案，能够以低成本对化粪池废水进行抛光。然而，迄今为止，关于种植对处理效率的影响仍然知之甚少。在这里，我们报告了一个案例研究，该案例评估了部署在印度南部一所学校的两个近乎相同的水平次表面流动人工湿地（HSSF-CW）的性能。HSSF-CW具有相似的尺寸和结构，不同之处在于，其中种植了一种系统（Canna indica），而另一种系统则在没有植物的情况下运行。两种系统都以类似的水力加载速率（HLR）和水力停留时间（HRT）在84 mm天^-1下运行和3.7天分别处理化粪池的废水。该系统每两周监测一年，并评估其性能动力学，营养和有机物去除效率。 在两个使用BOD _5的系统中，均观察到生物化学需氧量（BOD ₅）和化学需氧量（COD）显着降低（p <0.05）种植和未种植系统的去除效率分别为67％和61％。尽管两个系统的废水均达到印度中央污染控制委员会（CPCB）设定的环境排放标准，但未种植系统中的总磷（TP）和总悬浮固体（TSS）去除量明显高于种植系统。种植系统（0.16天^-1和0.30天^-1）中TN（K _TN）和BOD ₅（K _BOD5）的一阶衰减率常数（K）高于未种植系统（0.09天^{- 1}和0.27天^-1）。大R ²种植系统获得的值（约0.90）表明一阶衰减模型可用于评估污染物的降解。植物贡献至7％（0.3克/米² /天）BOD ₅，18％（1.9克/米² /天）COD和5％（0.09克/米² /天）TN负载的去除。我们的数据表明，种植可有效改善人工湿地的处理效率，尽管此处的改善微不足道，但应注意的是，在这种情况下，锈病感染可能会限制植物的功效。