Removal of nutrients in constructed wetlands for wastewater treatment through plant harvesting – Biomass and load matter the most
Removal of nutrients in constructed wetlands for wastewater treatment through plant harvesting – Biomass and load matter the most
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DOI：
10.1016/j.ecoleng.2020.105962
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发表时间：
2020-08
影响因子：
3.8
通讯作者：
J. Vymazal
中科院分区：
文献类型：
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作者：
J. Vymazal
在水平潜流人工湿地处理城市污水中，营养盐的吸收作为去除过程通常被认为是可以忽略的。然而，能够证实这一假设的结果非常少。被隔离在地上生物质中并因此可用于收获的营养物的量被称为现存量，并且它由生物质中的营养物浓度和生物质本身两者决定。现存量的一般值在30-80 g N m− 2和2-6 g P m− 2之间变化，而城市废水的流入负荷约为950 g N m− 2 yr − 1和350 g P m− 2 yr −1。在这些条件下，现存量代表小于10%的氮负荷和5%的磷负荷。HF CWs中氮和磷的去除通常较低，因此，植物吸收去除负荷的百分比较高。在低负荷条件下，即，低于500（200）g N m-2 yr-1或100（50）g P m-2 yr-1，去除的氮或磷的部分可以显著更高。在我们的研究中，主要由高植物生物量和低流入负荷支持的高现存量（> 100 g N m− 2和10 g P m−2）的组合负责去除高达62%的氮和58%的磷。我们的研究结果进行了四个HF CWs在捷克共和国表明，在HF CWs中的营养物质去除植物的直接作用可能被低估，特别是在低流入负荷和高植物生物量的条件下。
Uptake of nutrients as a removal process in constructed wetlands with horizontal subsurface flow (HF CWs) treating municipal wastewater is usually considered negligible. However, there is very low number of results which would confirm this assumption. The amount of nutrients sequestered in the aboveground biomass, and thus available for harvesting, is called standing stock and it is determined by both nutrient concentration in the biomass and biomass itself. The common values of standing stock vary in the range of 30–80 g N m−2and 2–6 g P m−2while inflow loadings of municipal wastewater are around 950 g N m−2yr−1and 350 g P m−2yr−1. Under these conditions, the standing stock represents less than 10% of the nitrogen load and 5% of phosphorus load. Removal of nitrogen and phosphorus in HF CWs is usually low and therefore, the percentage of removed load by plant uptake is higher. Under the conditions of low loadings, i.e., less that 500 (200) g N m−2yr−1or 100 (50) g P m−2yr−1, the portion of removed nitrogen or phosphorus could be substantially higher. In our study, the combination of high standing stocks (> 100 g N m−2and 10 g P m−2) supported primarily by high plant biomass and low inflow loadings was responsible for removal of up to 62% of nitrogen and 58% of phosphorus. The results of our study carried out in four HF CWs in the Czech Republic indicate that the direct role of plants in nutrient removal in HF CWs may be underestimated especially under conditions of low inflow loading and high plant biomass.