School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China.
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Sci Total Environ. 2022 Jan 1;802:149855. doi: 10.1016/j.scitotenv.2021.149855. Epub 2021 Aug 24.
In order to realize the active and synchronous control of nitrogen (N) and organic matter (OM) release from sediments, this study compared the spatiotemporal changes in the physical, chemical, and biological indicators in the water system under different CaO dosing modes. Results from 90-day incubation experiment showed that CaO formed a dense barrier layer near its dosing position, improved the anoxic condition of water system, increased the physical adsorption of pollutants by sediments, and reduced the nutrients in overlying water, interstitial water, and sediments. Comprehensive comparison, the improvement effect of shallow injection group (I1) was the most obvious. Meanwhile, the activities of ammonia oxidizing bacteria and nitrite oxidizing bacteria near dosing position and those of denitrifiers and anammox bacteria adjacent to dosing site were significantly increased in all test groups (p < 0.01), thereby realizing the biological removal of N and OM in sediments. In addition, DO and ORP were steadily higher than 5 mg L and 100 mV in I1, where the NH-N concentration in overlying water was stable below 1 mg L, and the easily released N content in the upper (0-3 cm) and middle (4-6 cm) sediments decreased by 41.64% and 43.56%, respectively. Compared with the large pollutant flux in control (14.31 TN mg m d and 194.05 mg TCOD m d), I1 completely inhibited the pollutant release and reduced the original nutrients in overlying water. In general, CaO efficiently and synchronously controlled the endogenous release of N and OM under the combined actions of physical interception, physical adsorption, chemical oxidation, and biological transformation. Therefore, this study may provide valuable reference and guidance for the active and synchronous removal of N and OM in sediments and inhibition of endogenous pollutant release under anoxic condition.
为了实现沉积物中氮（N）和有机物（OM）的主动同步释放控制，本研究比较了不同 CaO 投加方式下水体系统理化生指标的时空变化。90 天培养实验结果表明，CaO 在投加点附近形成致密的阻隔层，改善了水体的缺氧条件，增加了沉积物对污染物的物理吸附，降低了上覆水、间隙水和沉积物中的营养物质。综合比较，浅层注射组（I1）的改善效果最为明显。同时，所有试验组投加点附近氨氧化菌和亚硝酸盐氧化菌的活性以及投加点附近反硝化菌和厌氧氨氧化菌的活性均显著增加（p<0.01），从而实现了沉积物中 N 和 OM 的生物去除。此外，I1 中的 DO 和 ORP 稳定高于 5mg/L 和 100mV，上覆水中的 NH-N 浓度稳定低于 1mg/L，上（0-3cm）和中（4-6cm）沉积物中易释放 N 含量分别降低了 41.64%和 43.56%。与对照（14.31TNmgm d 和 194.05mgTCODm d）的大污染物通量相比，I1 完全抑制了污染物的释放，并减少了上覆水中的原始营养物质。总的来说，CaO 通过物理截留、物理吸附、化学氧化和生物转化的协同作用，高效且同步地控制了 N 和 OM 的内源性释放。因此，本研究可为缺氧条件下沉积物中 N 和 OM 的主动同步去除以及内源污染物释放的抑制提供有价值的参考和指导。
