曝气扰动下底泥氮的释放动力学及硝化反硝化过程研究

摘要

[目的]研究曝气扰动下底泥氮的释放动力学及硝化反硝化过程，以期解决底泥氮释放及二次污染问题。[方法]研究了底泥原位曝气对氮污染物释放的影响，并对其释放动力学参数进行解析，同时模拟了间歇曝气下泥水界面硝化反硝化脱氮过程。[结果]底泥曝气加速了氮污染物的释放，30min后底泥NH4＋-N与达到释放平衡；最大释放量与底泥扰动强度成正比，在曝气头距离泥面距离为0、1、2和3cm时（扰泥量为3．52、3．41、3．26和3．01g/L），NH4＋．N与最大释放量分别为14.3、13．8、13．2、12．2mg／L和33.2、30．9、29.8、27．3mg／L；且两者的释放动力学均符合舣常数方程。持续曝气可促进泥水界面硝化反应发生，8d后NH4＋-N浓度由12．4mg／L下降至0．2mg／L，硝态氮浓度达到最大值；停止曝气12d后，硝态氮与总氮浓度分别由10．8和37．4mg／L下降至0．36和23．2mg／L，说明有反硝化脱氮现象发生。可见，底泥曝气可促进氮污染物的释放及硝化过程，而通过间歇曝气，可实现底泥原位硝化反硝化脱氮。[结论]该研究结果可为城市黑臭河道底泥原位修复提供技术借鉴。%[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.