大连某TPH污染场地原位强化过硫酸钠修复技术研究
发布时间:2018-01-11 06:10
本文关键词:大连某TPH污染场地原位强化过硫酸钠修复技术研究 出处:《沈阳大学》2017年博士论文 论文类型:学位论文
更多相关文章: 原位化学氧化 过硫酸钠 TPH污染土壤 土壤修复
【摘要】:石油类污染场地是指由于人类活动产生的石油类污染物(TPH,Total petroleum hydrocarbon)超过一定阈值,对环境介质造成污染,且对人体健康造成危害的场地,具有成分复杂,污染浓度高、分布广、环境危害性强的特点。由于对污染场地的二次利用以及对土壤安全性的需求,如何快速有效的修复TPH污染场地是必要解决的问题,也是难点问题。化学氧化技术是修复TPH污染土壤的一个快速而有效的方法,其关键在于氧化剂的选择以及高效安全的应用方式。本研究以大连某TPH污染场地为研究对象,通过场地调查和风险评估确定需要修复的污染物类型、浓度、分布范围和修复目标,筛选适合该场地修复用的氧化剂组合,研究其最佳的应用方式、影响因素和降解机制等,并利用自制的土壤修复设备模拟氧化剂对该场地表层及深层污染土壤的修复,探明化学氧化过程中TPH的迁移转化规律,为设计本场地原位化学氧化修复技术方案提供数据支撑和理论依据。主要研究结果如下:(1)通过对污染场地自然地理环境、水文地质特征、企业生产情况的调查以及土壤和地下水中可能存在的有机污染物和重金属的监测分析,确定本场地需修复的污染物类型、范围和浓度。结果表明地下水中20种污染物均未超过筛选值,场地主要为土壤TPH污染,浓度范围19.8~52500 mg/kg。修复区域为场地溶剂库房表层(0~20cm)、废液库房(0~430 cm)及油泥处理区表层(0~60 cm),修复土方量合计3168.4m_3,其中重点修复区域为废液库房,所需修复面积615.7 m2,修复土方量2647.5m_3。(2)通过理论计算与小试实验对比了不同氧化剂的修复效率和氧化剂的需求量,并以此为基础,综合考虑土壤自然氧化剂需求、氧化剂的稳定性、地下环境传质特性、修复成本以及场地自然条件等因素,选择过硫酸钠(Na_2S_2O_8)为本场地修复用氧化剂;研究了不同方法活化时Na_2S_2O_8对TPH污染土壤的氧化处理效果:添加Fe~(2+)/柠檬酸(CA)活化的效果最佳,Na_2S_2O_8的投加量在2 mmol/g土较为适宜,且一次添加的去除效果比序批添加降解效率更高,土壤TPH的去除率为40.8%;利用探针化合物研究了不同时间节点内Fe~(2+)活化Na_2S_2O_8去除土壤中TPH的机理:Fe~(2+)/CA活化反应较快,30 min内反应基本完成,其降解TPH的主要物质是SO4-·、·OH等自由基,土壤中天然存在以及反应中产生的还原性物质促进了TPH的降解。(3)采用Na_2S_2O_8/过氧化钙(CaO_2)/Fe~(2+)/CA的组合修复场地表层TPH污染土壤,以克服单独使用Fe~(2+)/CA活化带来的水溶性氧化剂/活化剂流失严重、土壤酸化、副产物SO42-过高的缺陷。结果表明:使用Na_2S_2O_8/CaO_2的组合,摩尔用量比为2.5较为合适,反应7天TPH去除率为67.4%。使用Na_2S_2O_8/Ca O_2/Fe~(2+)/CA的方法,当摩尔用量比为5/2/1/1时,TPH降解率为82.1%,反应比较温和,反应后土壤体系pH呈中性。土壤水相中TPH和SO42-的浓度均低于筛选值,对环境的影响较小。利用探针化合物对Na_2S_2O_8/CaO_2/Fe~(2+)/CA体系去除土壤TPH的机制研究表明,TPH降解过程中不仅有SO4-·、OH·等自由基的作用,CaO_2也参与了直接氧化,168 h内反应基本完成。(4)通过自制的土壤修复模拟设备,采集污染场地土壤,按照实际地层状况进行按比例缩小重塑。采用表层土壤混合、淋滤、下层土壤注射井注入/抽出地下水配制氧化剂溶液循环利用等方式,对大连某TPH污染场地土壤进行原位Na_2S_2O_8氧化修复模拟。结果表明:上层土壤混合Ca O_2和Na_2S_2O_8后喷洒FeSO_4/CA可以有效修复表层污染土壤,20天后土壤TPH降解率达到最高,平均值为98.5%;下层土壤注射井注入Na_2S_2O_8/FeSO_4/CA,在蠕动泵压力0.2 Mpa,流速10 mL/min,地下水流速0.08 m/d条件下,Na_2S_2O_8在模拟土体中的传输能力较强,持续注入3天,氧化剂迁移至饱和层,影响半径约为0.2 m。持续注入7天时氧化剂影响半径约为0.4 m,氧化剂基本充满饱和层,此时土壤TPH降解率达到最高,平均为95.6%。土壤溶液pH和土壤温度监测值分别为5.9~7.6和7~21℃,表明该方法的环境次生影响较小。(5)根据场地调查和中试模拟所得技术参数,设计本场地TPH污染土壤原位化学氧化修复工程技术方案。对于溶剂库房表层(0~20 cm)、油泥处理区表层(0~60 cm)和废液库房表层污染土壤,采取原位混合淋滤的方法,修复药剂为Na_2S_2O_8/CaO_2/Fe~(2+)/CA;对于废液库房深层污染土壤(60~430 cm)采取原位注射的方法,修复药剂为Na_2S_2O_8/Fe~(2+)/CA。井间距4米,初始注入压力1 Mpa,修复期为60天。
[Abstract]:Oil pollution site is due to human activities have petroleum pollutants (TPH, Total petroleum hydrocarbon) exceeds a certain threshold, pollute the environment and harm to the media sites on human health, has complex composition, high concentration of pollution, wide distribution, environmental hazards and strong characteristics. Because the two use of pollution the site and the demand for the safety of the soil, how to quickly and effectively repair TPH contaminated sites is necessary to solve the problem, which is also a difficult problem. Chemical oxidation technology is a rapid and effective method for the remediation of TPH contaminated soil, the key lies in the application of oxidants and high safety. The study in Dalian Province TPH contaminated sites as the research object, through the site investigation and risk assessment to determine the need to repair the pollutant type, concentration, distribution and repair, suitable for the screening of site remediation Combination of oxidizing agent, studied the best application mode, influencing factors and degradation mechanisms, and the use of soil remediation equipment homemade oxidation repair agent on the ground simulation of surface and deep soil pollution, migration and transformation regularity of chemical oxidation process of TPH, provide data support and theoretical basis for the design of repair technology field in situ chemical oxidation. The main results are as follows: (1) based on the contaminated natural geographical environment, hydrogeological characteristics, analysis of possible production situation investigation and soil and groundwater organic pollutants and heavy metals monitoring, determine the site to repair the types of pollutants, and the concentration range. The results showed that 20 kinds of contaminants in groundwater did not exceed the value of screening, the main venue for soil TPH pollution, the concentration range of 19.8~52500 mg/kg. repair area for site surface (0~20cm) solvent storeroom The warehouse (0~430 cm), wastewater sludge treatment and surface area (0~60 cm), total repair of earthwork 3168.4m_3, which focus on the repair area for waste storeroom, the required repair area of 615.7 m2, 2647.5m_3. repair earthwork (2) by comparing the theoretical calculation and experiment of the repair efficiency and oxidant different oxidant demand the amount, and on this basis, considering the soil natural oxidant demand, the stability of the oxidant, the underground environment and mass transfer characteristics, the cost of repair and site factors such as natural conditions, selection of sodium persulfate (Na_2S_2O_8) as oxidant for the site repair; studied the activation of Na_2S_2O_8 in TPH contaminated soils: add oxidation treatment Fe~ (2+) / citric acid (CA) activation of the best effect, the dosage of Na_2S_2O_8 2 mmol/g in the soil is suitable, and an added removal effect than batch add higher degradation efficiency, soil TPH The removal rate was 40.8%; of different time node using Fe~ probe compound (2+) removal mechanism of soil TPH activation in Na_2S_2O_8: Fe~ (2+) /CA activation reaction rapidly, within 30 min was completed, the main substance of the degradation of TPH is SO4-, OH and other free radicals, reducing substances from natural there are soil and in response to promote the degradation of TPH. (3) using Na_2S_2O_8/ calcium peroxide (CaO_2) /Fe~ (2+) /CA composite repair site surface TPH contaminated soil, in order to overcome the single use of Fe~ (2+) /CA activation of water soluble oxidant / activator erosion, soil acidification that defect by-product SO42- high. The results show that the combination of Na_2S_2O_8/CaO_2, molar ratio of 2.5 is more appropriate, reaction 7 days the removal rate of TPH using Na_2S_2O_8/Ca O_2/Fe~ 67.4%. (2+) /CA method, when the molar ratio was 5/2/1/1, the degradation rate of TPH was 82.1%, the reaction Mild reaction after soil system pH is neutral. The concentration of TPH and SO42- in soil solution was lower than the value of screening, less impact on the environment. Using Na_2S_2O_8/CaO_2/Fe~ probe compound (2+) mechanism of /CA system for removal of soil TPH showed that the degradation process of TPH is not only in the SO4-, OH and other free radicals CaO_2, is also involved in the direct oxidation reaction basically completed within 168 H. (4) through soil remediation selfmade simulation equipment, acquisition of contaminated soil, were scaled according to the actual situation. The remodeling of formation of surface soil mixing, leaching, soil injection wells injection / extraction of groundwater prepared oxidant solution recycling etc. Na_2S_2O_8, in situ oxidation repair simulation of a Dalian TPH contaminated soil. The results showed that: Ca O_2 and Na_2S_2O_8 mixed soil after spraying FeSO_4/CA can effectively repair the surface of polluted soil After 20 days of soil, soil degradation rate of TPH reached the highest, the average value of 98.5%; lower soil injection wells of Na_2S_2O_8/FeSO_4/CA injection on the peristaltic pump pressure of 0.2 Mpa, a flow rate of 10 mL/min, the underground water flow rate under the condition of 0.08 m/d, transmission capacity of Na_2S_2O_8 in the simulation of soil in strong, continuous injection of 3 days, the oxidant migration to the saturated layer the influence radius is about 0.2 M., continuous injection of 7 days oxidant influence radius is about 0.4 m, oxidant basic saturated layer, the soil degradation rate of TPH reached the highest, the average 95.6%. pH of soil solution and soil temperature monitoring value were 5.9~7.6 and 7~21 C, that this method has a smaller environment (secondary effects. 5) according to the simulation results of site investigation and test technical parameters, design the site of TPH contaminated soil remediation technology for in situ chemical oxidation. For the solvent warehouse (0~20 cm), the surface area of the surface of sludge treatment (0~60 cm) and waste water The storehouse surface contaminated soil, adopt the method of in situ leaching mixed, repair agent for Na_2S_2O_8/CaO_2/Fe~ (2+) /CA; for the waste warehouse deep contaminated soil (60~430 cm) by in situ injection, repair agent for Na_2S_2O_8/Fe~ (2+) /CA. well spacing of 4 meters, the initial injection pressure of 1 Mpa, the repair period is 60 days.
【学位授予单位】:沈阳大学
【学位级别】:博士
【学位授予年份】:2017
【分类号】:X53
【相似文献】
相关期刊论文 前10条
1 刘洪泉;杨亚玲;张丹扬;;靛红-过硫酸钠体系催化动力学光度法测定土壤中镍(Ⅱ)[J];光谱实验室;2010年01期
2 林尧林;稳定的过硫酸钠制备[J];天津化工;1994年02期
3 李梦姣;刘菲;陈鸿汉;黄伟英;;菱铁矿催化过氧化氢-过硫酸钠修复地下水中1,2-二氯乙烷污染[J];环境工程学报;2014年04期
4 蒋慧灵;臧娜;钱新明;傅智敏;;过硫酸钠和过硫酸钾的热稳定性分析[J];化工学报;2006年12期
5 张宇飞;;使用过硫酸钠氧化除钴的实验研究[J];新疆有色金属;2012年S1期
6 顾小钢;吕树光;徐e,
本文编号:1408398
本文链接:https://www.wllwen.com/shoufeilunwen/gckjbs/1408398.html