Research on the application of oxygen micro-nanobubbles in-situ remediation of groundwater
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摘要:
微纳米气泡具有气泡粒径小、比表面积大、溶解氧浓度高、在水中停留时间长、传质效率高等特性,因而在地下水有机物污染原位修复领域具有很好的应用前景。选择南方某简易垃圾填埋场作为试验场地,采用微纳米气泡制备-注射一体化装置,研究抽提协同、注射流量、注射持续时间等工艺条件对氧气微纳米气泡传质和地下水污染物降解修复效果的影响。结果表明:相对于普通空气曝气,氧气微纳米气泡在水体内溶解氧浓度峰值更高,持续作用时间更长,抽提作用可显著提高微纳米气泡传质效率,提升影响半径,强化污染物去除效果。多轮注射+抽提联用工艺条件下,注射影响半径可达到4 m,COD去除率达96.1%,NH3-N去除率达92.4%,但注射停止后存在一定的反弹现象。
Abstract:Micro-nanobubbles have the characteristics of small bubble particle size, large specific surface area, high dissolved oxygen concentration, long residence time in water and high mass transfer efficiency. Therefore, they have a good application prospect in the field of in-situ remediation of organic pollutants in groundwater. A simple landfill in the south of China was selected as the test site, and the micro-nanobubble preparation and injection integrated device was used to study the effects of process conditions such as extraction synergy, injection flow and injection duration on the mass transfer of oxygen micro-nanobubbles and the degradation and remediation of groundwater pollutants. The test showed that compared with ordinary air aeration, the oxygen concentration peak of oxygen micro-nanobubbles in water was higher and lasted longer. The extraction could significantly improve the mass transfer efficiency of micro-nanobubbles, enhance the influence radius and strengthen the degradation and removal effect of pollutants. Under the condition of multi-round injection-extraction combined processes, the injection influence radius could reach 4 m, with the removal rate of COD and NH3-N reaching 96.1% and 92.4%, respectively. However, there was a certain rebound after the injection was stopped.
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Key words:
- oxygen micro-nanobubbles /
- aeration /
- landfill /
- groundwater /
- in-situ remediation
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表 1 地下水检测指标及分析方法
Table 1. Groundwater detection indexes and detection methods
检测指标 检测方式 分析方法 水位、电导率、ORP、DO 现场快速检测 pH、色度、溶解性总固体、总硬度、化学需氧量(CODCr)、生化需氧量(BOD5)、硫化物、阴离子表面活性剂、硫酸盐、氯化物、NH3-N、总氮、高锰酸盐指数(CODMn) 实验室送检 GB/T 14848—2017 砷、镉、铬(六价)、铜、铅、汞、镍 实验室送检 GB/T 14848—2017 挥发性有机物(VOCs)、半挥发性有机物(SVOCs) 实验室送检 GB/T 14848—2017 表 2 地下水水质检测结果
Table 2. Groundwater quality test results
指标 单位 检测结果 GB/T 14848—
2017 Ⅲ类限值超标倍数 CODCr mg/L 115 BOD5 mg/L 8.1 ORP mV −82.5 DO mg/L 1.2 CODMn mg/L 30.9 ≤3 9.3 NH3-N mg/L 109 ≤0.5 217 邻苯二甲酸二甲酯 μg/L 1.3 砷 μg/L 50.8 ≤10 4.1 表 3 不同气泡源特性对比试验条件
Table 3. Experimental conditions for comparison of characteristics of different bubble sources
气泡性质 制备设备 通气量/(L/h) 通气时间/h 毫米级空气气泡 空压机 30 0.5 空气微纳米气泡 微纳米气泡发生装置 30 0.5 氧气微纳米气泡 微纳米气泡发生装置 30 0.5 表 4 不同注射工况对比试验条件
Table 4. Comparative test conditions under different injection conditions
组别 注射流量/
(m3/h)注射时
间/h抽提流量/
(m3/h)抽提时
间/h注射
轮次/次每轮次注射
时间段1 1.0 12 1 12 1 08:00—20:00 2 1.0 12 0 0 1 08:00—20:00 3 1.0 12 1 12 1 08:00—20:00 4 1.5 12 1 12 1 08:00—20:00 5 1.0 36 1 36 3 08:00—20:00 注:组别1、3为相同注射、抽提条件下,不同时间点开展的2组试验。 表 5 污染物浓度反弹信息
Table 5. Pollutant concentration rebound information
项目 CODCr NH3-N浓度 MW03井 MW04井 MW03井 MW04井 初始浓度/(mg/L) 543 480 136 102.6 3轮注射后浓度/(mg/L) 21 209 10.3 73.0 污染物去除率/% 96.1 56.5 92.4 28.8 3轮注射后2 d浓度/(mg/L) 170 251 54.1 77.8 污染物去除率/% 68.7 47.7 60.2 24.2 -
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