Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing, 210044, China.
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing, 210044, China.
Environ Sci Pollut Res Int. 2020 Aug;27(23):29475-29484. doi: 10.1007/s11356-020-09274-2. Epub 2020 May 22.
Many constructed wetland systems are facing the problem of low dissolved oxygen (DO) and reduced nitrogen removal efficiency. In this study, an experimental constructed wetland system is designed and used to investigate the effect of biochar (rice husk biochar (RHB), coconut shell biochar (CSB), and wood biochar (WB) and earthworm on DO concentration, nitrogen transformation, and ammonia nitrogen removal. Specifically, effects of different biochar and earthworm on NH-N in wastewater, N content of Phragmites australis, NH-N and NO-N content in substrates, microbial nitrification and denitrification potentials, and the DO concentration were investigated. Results show that the addition of biochar and earthworm increased the removal efficiency of NH-N from wastewater. The addition of RHB and WB significantly increased the concentration of DO by 21.4% and 25.7% (P < 0.05) respectively in the constructed wetland. The addition of earthworm significantly increased the DO concentration in the constructed wetland system by an average of 30.35% (P < 0.05).The N content of P. australis increased when biochar and earthworm were introduced into the constructed wetland system, with higher relative N content observed in the above-ground biomass. NO-N content increased, but NH-N decreased in the substrate. Addition of both biochar and earthworm increased nitrification and denitrification potentials. However, no significant increase in denitrification potential was observed when only biochar was added. The removal efficiency of NH-N from wastewater is significantly positively correlated with the DO, nitrification, and denitrification potential, and nitrogen content of above-ground part of P. australis (P < 0.05). Results suggest that the DO concentration in constructed wetland systems could be improved by the addition of biochar and earthworm. These findings imply that both biochar and earthworm could be added into constructed wetlands to solve the low DO concentration and improve the removal efficiency of nitrogen.
许多人工湿地系统都面临溶解氧（DO）低和脱氮效率降低的问题。本研究设计并使用了一个实验性人工湿地系统，以研究生物炭（稻壳生物炭（RHB）、椰子壳生物炭（CSB）和木生物炭（WB）和蚯蚓对 DO 浓度、氮转化和氨氮去除的影响。具体而言，研究了不同生物炭和蚯蚓对废水中 NH-N、芦苇（Phragmites australis）中 N 含量、基质中 NH-N 和 NO-N 含量、微生物硝化和反硝化潜力以及 DO 浓度的影响。结果表明，添加生物炭和蚯蚓提高了废水中 NH-N 的去除效率。添加 RHB 和 WB 可分别使人工湿地中 DO 的浓度提高 21.4%和 25.7%（P<0.05）。添加蚯蚓可使人工湿地系统中的 DO 浓度平均提高 30.35%（P<0.05）。当生物炭和蚯蚓被引入人工湿地系统时，芦苇的 N 含量增加，地上部分的相对 N 含量更高。NO-N 含量增加，但基质中的 NH-N 减少。添加生物炭和蚯蚓均可提高硝化和反硝化潜力。然而，仅添加生物炭时，反硝化潜力没有显著增加。废水中 NH-N 的去除效率与 DO、硝化和反硝化潜力以及芦苇地上部分的 N 含量呈显著正相关（P<0.05）。结果表明，添加生物炭和蚯蚓可以提高人工湿地系统中的 DO 浓度。这些发现表明，生物炭和蚯蚓都可以添加到人工湿地中，以解决低 DO 浓度和提高氮去除效率的问题。
