Department of Chemistry, University of A Coruña, Rúa da Fraga 10, 15008, A Coruña, Galiza, Spain.
Environ Sci Pollut Res Int. 2017 Oct;24(28):22649-22662. doi: 10.1007/s11356-017-9925-1. Epub 2017 Aug 15.
The effect of step-feeding (untreated wastewater by-pass) on the performance of lab-scale columns simulating a hybrid vertical flow (VF)-horizontal flow (HF) constructed wetland (CW) system was studied. Step-feeding strategies have been adopted in several kinds of CW, but this is the first report about the use of step-feeding in VF + HF hybrid systems treating domestic wastewater. Applied loading rates were 7-11 g BOD/m day and 2.1-3.4 g TN/m day (overall system). Removal efficiency reached 98% TSS and COD and 99% BOD on average, whilst a 50% by-pass improved TN removal from 31 to 50%. Maximum surface nitrification rate (5.5 g N/m day) was obtained in VF unit, whilst maximum denitrification rate (1.8 g N/m day) was observed in HF unit. Referred to the overall system, maximum surface nitrification and denitrification rates were 2.2 and 1.6 g N/m day, respectively. However, potential nitrifying and denitrifying activities (batch assays) were 15.0 and 58.9 g N/m day, respectively. Even at 50% by-pass, operational conditions in HF unit (dissolved oxygen, redox, COD/TN ratio) were not suitable enough for denitrification. However, methane emissions were not observed and nitrous oxide emissions were relatively low.
本研究考察了分步进水（未经处理的污水旁路）对模拟混合垂直流（VF）-水平流（HF）人工湿地（CW）系统的实验室规模柱性能的影响。分步进水策略已在多种 CW 中得到应用，但这是首次在 VF+HF 混合系统中使用分步进水处理生活污水的报道。应用的负荷率分别为 7-11 g BOD/m 天和 2.1-3.4 g TN/m 天（整个系统）。平均而言，去除效率达到了 TSS 和 COD 的 98%和 BOD 的 99%，而 50%的旁路提高了 TN 的去除率，从 31%提高到 50%。VF 单元的最大表面硝化速率（5.5 g N/m 天），而 HF 单元的最大反硝化速率（1.8 g N/m 天）。就整个系统而言，最大表面硝化和反硝化速率分别为 2.2 和 1.6 g N/m 天。然而，潜在的硝化和反硝化活性（批量试验）分别为 15.0 和 58.9 g N/m 天。即使在 50%的旁路条件下，HF 单元的操作条件（溶解氧、氧化还原电位、COD/TN 比）仍不足以进行反硝化。然而，没有观察到甲烷排放，氧化亚氮排放相对较低。
