CIESC Journal ›› 2022, Vol. 73 ›› Issue (11): 5118-5127.DOI: 10.11949/0438-1157.20221012

• Energy and environmental engineering • Previous Articles     Next Articles

Study on the control effect of electrokinetic drainage of pore water on nitrogen release flux at the mud-water interface

Junjun GU1,2(), Rui LI1,2, Xingyi WU1,3, Xianqiang TANG1,2(), Yanping HU1,2   

  1. 1.Basin Water Environmental Department, Changjiang River Scientific Research Institute, Wuhan 430010, Hubei, China
    2.Key Laboratory of Basin Water Resource and Eco-Environmental Science in Hubei Province, Wuhan 430010, Hubei, China
    3.Yichang Dongfengqu Irrigation District Administration, Yichang 443199, Hubei, China
  • Received:2022-07-20 Revised:2022-10-12 Online:2022-12-06 Published:2022-11-05
  • Contact: Xianqiang TANG

电动导排孔隙水对泥-水界面氮释放通量的控制效果研究

顾鋆鋆1,2(), 黎睿1,2, 吴兴熠1,3, 汤显强1,2(), 胡艳平1,2   

  1. 1.长江科学院流域水环境研究所,湖北 武汉 430010
    2.流域水资源与生态环境科学湖北省重点实验室,湖北 武汉 430010
    3.宜昌市东风渠灌区管理局,湖北 宜昌 443199
  • 通讯作者: 汤显强
  • 作者简介:顾鋆鋆(1998—),女,硕士研究生,gujunjun0108@foxmail.com
  • 基金资助:
    中央级公益性科研院所基本科研业务项目(CKSF2021531/SH);国家自然科学基金项目(51979006);国家高层次人才特殊支持计划项目(CKSD2019542/SH)

Abstract:

Pore water is a crucial storage medium and a key source of sediment nitrogen. The separation and removal of nitrogen rich pore water is a potential scheme to control the release of endogenous nitrogen. A novel electrokinetic drainage of pore water device was used in a simulation study to understand its efficacy on internal nitrogen release. A total of three groups of experiments were set up: control, gravity drainage (0 V/cm voltage gradient) and intermittent energization (0.5 V/cm voltage gradient, 4 h On/4 h Off). In this research, we analyzed the characteristics of nitrogen concentration and release flux at the sediment-water interface, monitored the pore water and sediment nitrogen fraction, pH and other physicochemical parameters, and then assessed the effect of electrically induced and discharged pore water on the release flux of nitrogen at the sediment-water interface and the influencing factors. The results show that electrokinetic drainage of pore water can reduce the nitrogen release flux at the sediment-water interface effectively. The cumulative dissolved total nitrogen (DTN) release flux at the sediment-water interface was 282.28 mg N/m2 after 632 h of intermittent energization, which was 95.61% lower than that in the control group. Electric drainage of pore water makes the anode pore water acidic and the cathode pore water alkaline, and the change of pH promotes the activation of transformable nitrogen (TTN) in the sediment. The removal rate of sludge ion-exchanged nitrogen (IEF-N) increased from 11.11%—12.97% to 12.59%—22.31%. After electric drainage of pore water, the total nitrogen removal amount of sediment is 47015.72 mg/m3, and the cumulative energy consumption is 162.38 kWh/m3.

Key words: electrokinetic remediation, electrochemistry, deposition, remediation, nitrogen release flux, pore water, nitrogen fraction

摘要:

孔隙水是底泥氮素污染的主要载体和释放源头,对富含氮素的孔隙水予以分离和脱除是控制内源氮释放的潜在方案。以富营养化湖泊底泥为研究对象,采用自制底泥孔隙水电动导排装置,在上覆水深度为20 cm的条件下进行底泥孔隙水电动导排,共设置对照、重力排水(0 V/cm电压梯度)和间歇通电(0.5 V/cm电压梯度,4 h On/4 h Off)3组实验,分析了泥-水界面氮浓度及释放通量的变化特征,监测了孔隙水及底泥中氮形态、pH等理化参数,评估了电动导排孔隙水对泥-水界面氮释放通量的控制效果及影响因素。结果表明:电动导排孔隙水可有效降低泥-水界面的氮释放通量,实验进行632 h后,通电实验组泥-水界面累计DTN释放通量为282.28 mg N/m2,与对照组相比氮释放通量削减95.61%。电动导排孔隙水使阳极孔隙水呈酸性,阴极孔隙水呈碱性,pH的改变促进了底泥中可转化态氮(TTN)的活化,与重力排水相比,电动导排孔隙水后底泥离子交换态氮(IEF-N)去除率由11.11%~12.97%提升至12.59%~22.31%。电动导排孔隙水后底泥总氮脱除量为47015.72 mg/m3,累计能耗为162.38 kWh/m3

关键词: 电动导排, 电化学, 沉积物, 修复, 氮释放通量, 孔隙水, 氮形态

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