Li Mengting, Ge Shuhan, Zhang Jian, Wu Shubiao, Wu Haiming, Zhuang Lin-Lan
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao 266237, China.
College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao 266237, China.
Sci Total Environ. 2022 Sep 20;840:156667. doi: 10.1016/j.scitotenv.2022.156667. Epub 2022 Jun 12.
The limitation of oxygen and carbon source restricted the TN removal in constructed wetland (CW). Algal pond (AP) could produce oxygen and fix CO to improve C/N ratio in water. Therefore, an AP-CW system was established under laboratory conditions to deeply explore the effect of nutrient load distribution and microalgae addition in CWs on pollutant removal. This study showed that AP-CW could remove 49.7% TN and 90.0% TP with no carbon addition in CWs. The significant removal of NH-N by AP advanced the location of denitrification in CWs. To enhance TN removal, different dosage of microalgae were intermittently added at 20 and 10 cm respectively below the inlet of the vertical flow CW1 and CW2, where the rest NH-N has been almost oxidized into nitrate. The addition of microalgae influenced the microflora and effluent quality. Microalgae dosage in denitrification area significantly increased the absolute abundance of Σnir. The best TN removal of AP-CW could reach 91.3% when 8 g (dry weight) microalgae was added. However, unlike previous knowledge, microalgae as an organic carbon source would also release N and P during decomposition, leading to increased nutrients in the effluent. The optimal dosage of microalgae was 1 g/5 d in this study. The position and amount of microalgae addition in CWs should be adjusted based on water property and element flow to achieve the best pollutant removal and biomass harvest.
氧气和碳源的限制制约了人工湿地（CW）中总氮（TN）的去除。藻池（AP）可以产生氧气并固定二氧化碳以提高水中的碳氮比。因此，在实验室条件下建立了一个AP-CW系统，以深入探究人工湿地中营养负荷分布和微藻添加对污染物去除的影响。本研究表明，在人工湿地不添加碳源的情况下，AP-CW系统能够去除49.7%的TN和90.0%的总磷（TP）。藻池对氨氮（NH-N）的显著去除推进了人工湿地中反硝化作用的位置。为了提高TN的去除率，分别在垂直流CW1和CW2进水口以下20厘米和10厘米处间歇性添加不同剂量的微藻，此处剩余的NH-N几乎已被氧化成硝酸盐。微藻的添加影响了微生物群落和出水水质。反硝化区域的微藻剂量显著增加了Σnir的绝对丰度。当添加8克（干重）微藻时，AP-CW系统对TN的最佳去除率可达91.3%。然而，与以往认知不同的是，微藻作为有机碳源在分解过程中也会释放氮和磷，导致出水中营养物质增加。本研究中微藻的最佳添加剂量为1克/5天。应根据水质和元素流动情况调整人工湿地中微藻的添加位置和数量，以实现最佳的污染物去除和生物质收获。
