基于水位调控的垂直流人工湿地强化脱氮研究

ENHANCED NITROGEN REMOVAL OVER SATURATED WATER LEVEL REGIME IN VERTICAL FLOW CONSTRUCTED WETLAND

  • 摘要: 文章以垂直流人工湿地为研究对象, 探究了水位调控对湿地系统脱氮性能的影响效果及影响机制。结果表明, 水位调控可以优化湿地内部的不饱和层、饱和层分布, 提高系统对化学需氧量和氨氮的去除效果, 进而提高脱氮能力。当饱和水位高度为70 cm时(基质床高度为90 cm), 系统的总氮去除率最高, 为53.6%。氮循环功能基因的结果表明, 饱和水位降低后所创造的不饱和层并未对反硝化菌群造成负面影响, 不饱和层中富集的亚硝酸盐氧化菌, 可以实现同步硝化反硝化。但过低的饱和水位(20 cm)会引起不必要的碳源损失, 导致反硝化过程受限, 脱氮效率降低。由此, 在垂直流人工湿地实际应用时, 可以通过水位调控强化湿地系统的脱氮性能。

     

    Abstract: The partially saturated Vertical Flow Constructed Wetland (VFCW) has been reported to exhibit better nitrogen removal performance than unsaturated VFCW when treating domestic wastewater. However, it is unclear how saturated water level affects the nitrogen transforming and its removal in VFCW. Herein, three VFCWs were operated under 90, 70 and 20 cm saturated water level regime, respectively. The physicochemical parameters of influent and effluent, i.e., chemical oxygen demand (CODCr), total nitrogen (TN), ammonia (\rmNH^+_4-N), nitrate (\rmNO^-_3 -N), nitrite (\rmNO^-_2 -N), total phosphorus (TP), as well as the abundance of nitrogen transforming functional genes were investigated. The results showed that the purification performance of VFCW was improved by optimizing the distribution of unsaturated and saturated zones through saturated water level adjustment. The best nitrogen removal performance of 53.6% was obtained when the saturated water level height was 70 cm (media bed depth was 90 cm). The abundance of functional genes suggested that the unsaturated zone had no negative influence on denitrification community. The enriching nitrite oxidation bacteria in the unsaturated zone promoted the simultaneous nitrification and denitrification processes. However, too much low saturated water level (20 cm) might cause the unnecessary loss of carbon sources, resulting in the limited denitrification process and decreasing nitrogen removal efficiency. Hence, the saturated water level regime could be employed to improve the nitrogen removal performance in VFCW.

     

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