复合矿化稳定剂对砷污染土壤稳定效果及机理的研究

发布时间：2018-07-18 14:38

【摘要】：本课题以人工砷污染土壤为研究对象,选用含铁材料、含铝材料、含锰材料、含硫材料、碱性材料、粘土矿物、有机质等稳定药剂对砷污染土壤进行稳定化处理,筛选出效果较优的几种稳定药剂,再进行复配实验,确定最佳配比；然后对土壤含水量、土壤pH、竞争性离子、反应时间、污染初始浓度等稳定效果影响因素进行研究；接着运用生物有效性、浸出毒性、赋存形态及物相分析等方法,阐述添加稳定药剂处理后砷的迁移性、毒性、赋存形态及物相成分；最后,对稳定处理后的砷污染土壤进行模拟酸雨淋溶实验,为实际应用提供理论依据。实验结果表明：(1)稳定药剂的筛选与组配实验结果表明：砷污染土壤的最佳稳定药剂种类及配比为：主要稳定药剂FeS,投加量为Fe/As=15:1;pH调节剂电石渣,投加量为0.5%；土壤改良剂菌渣,投加量为6%；稳定处理后土壤砷的稳定效率达到90.53%,砷的浸出浓度为2.09 mg·L-1,低于《危险废物鉴别标准浸出毒性鉴别》GB 5085.3-2007标准值5 mg·L-。(2)土壤砷稳定效果影响因素实验结果表明：①土壤含水率以30%为宜,含水率太低,影响土壤和药剂之间的充分反应；含水率太高,砷的毒性和移动性加强,修复成本提高。②土壤pH偏酸性和中性有利于砷的稳定,碱性则有利于砷的溶出,其中pH在2.20-9.85时土壤砷的稳定效率变化不大,pH=6左右时砷的稳定效果最好,pH在9.85-12.01时土壤砷的稳定效率明显降低。③竞争性阴离子对土壤砷稳定效率的抑制作用表现为PO43-SO42-≈ NO3-Cl-,其中P043-的加入会明显降低土壤砷的稳定效率,8042-和N03-对砷的稳定效果有轻微的抑制作用,Cl-对砷稳定效率的影响很小。④随着反应时间的加长,土壤砷的稳定效率呈现先上升后平缓的趋势,反应时间15天时,砷的稳定效率为升至93.28%,持续增加反应时间至120天,砷的稳定效率变化不大。⑤土壤砷的稳定效率随着砷污染浓度的升高而降低,当砷污染浓度分别506 mg·kg-1和833 mg·kg-1时,砷的稳定效率分别为92.36%和90.53%,对砷的稳定处理效果良好；当砷污染浓度分别为2951 mg·kg-1 5290 mg·kg-1时,砷的稳定效率分别为55.57%和47.54%,对砷的稳定处理能力有限。(3)生物有效性分析结果表明：利用化学提取法和生理原理提取法浸提污染土壤,3组处理土壤的有效态砷和有机体内砷的可给量高低顺序为污染原土去离子水》稳定药剂,稳定处理能够明显降低土壤中砷的生物有效性,大幅度降低土壤有效态砷和有机体内砷的可给量。(4)浸出毒性分析结果表明：利用国标法(HJ/T299-2007)和TCLP法浸提污染土壤,3组处理土壤砷的浸出浓度高低顺序为污染原土去离子水》稳定药剂,稳定处理能够显著稳定和吸持土壤中的砷,大幅度降低砷的毒性浸出浓度。(5)赋存形态分析结果表明：稳定处理后的污染土壤中易溶态砷含量降低18.61%,铁型砷升高10.36%,钙型砷升高5.81%,稳定处理能有效将土壤中易溶态砷转化为铁型砷和钙型砷。(6)物相分析结果表明：稳定处理后的污染土壤新增了CaAl2Si2O8·4H20(斜方钙沸石)、Ca3Fe4+3(AsO4)4(OH)8·3H2O(：菱砷铁矿)、Fe2(AsO4)(SO4)OH · 5H2O(砷铁矾矿)、(Al,Fe+3)3AsO4(OH)8·5H2O(砷铁铝矿)四种矿物,稳定处理能促使土壤中的砷向矿物态砷转化。(7)模拟酸雨实验表明：①稳定处理土壤砷的淋出浓度随着淋洗时间延长维持在0.88mg·L-1～1.01 mg·L-1之间,远低于污染土壤中砷的淋出浓度17.79 mg.L-1～7.31mg·L-,稳定处理可以有效控制砷的溶出。②稳定处理土壤中砷的总量降低为9.63%,远低于污染原土的28.93%,主要由于稳定处理使土壤中的砷生成难溶性铁型砷和钙型砷,同时添加的菌渣增加了土壤缓冲能力,从而有效抵抗酸雨的冲刷。
[Abstract]:This subject takes artificial arsenic contaminated soil as the research object, selects the iron containing material, the aluminum containing material, the manganese bearing material, the sulfur bearing material, the alkaline material, the clay mineral, the organic matter and so on stabilizing agent to the arsenic contaminated soil, and selects several stable reagents which have the better effect, then the compound experiment is carried out to determine the optimum ratio; then the soil is determined. The influence factors such as water content, soil pH, competitive ion, reaction time, initial concentration of pollution and other factors are studied. Then, biological availability, leaching toxicity, occurrence form and phase analysis are used to explain the mobility, toxicity, occurrence form and phase composition of arsenic after the addition of stable agents. Finally, after stable treatment, it is treated steadily. The leaching experiment of simulated acid rain in arsenic contaminated soil provides theoretical basis for practical application. The experimental results show that: (1) the results of the selection of stable agents and the experimental results show that the best stable agent type and proportion of arsenic contaminated soil are the main stable agent FeS, the dosage of Fe/As=15:1, the calcium carbide slag of pH regulator, and the dosage of 0.5% The soil improvement agent residue was 6%, the stable efficiency of soil arsenic was 90.53% after stable treatment, and the leaching concentration of arsenic was 2.09 mg. L-1, which was lower than that of >GB 5085.3-2007 standard value 5 mg. L-. (2) for soil arsenic stability. The water content is too low to affect the full reaction between the soil and the medicament; the water content is too high, the toxicity and mobility of arsenic are strengthened and the repair cost is increased. The soil pH partial acid and neutrality is beneficial to the stability of arsenic, and the alkalinity is beneficial to the dissolution of arsenic. In the case of pH, the stability efficiency of the arsenic in soil changes little, and the stability of arsenic at about pH=6 is stable. The efficiency of soil arsenic stability decreased obviously when pH was at 9.85-12.01. (3) the inhibitory effect of competitive anions on soil arsenic stability was PO43-SO42- NO3-Cl-. The addition of P043- would obviously reduce the stability of arsenic in soil. 8042- and N03- have a slight inhibition effect on the stability of arsenic, and Cl- for arsenic stability efficiency. As the reaction time increased, the stability efficiency of soil arsenic increased first and then slowed down, and the stability efficiency of arsenic increased to 93.28% when the reaction time was 15 days, and the stability efficiency of arsenic was increased to 120 days, and the stability efficiency of arsenic changed little. The stable efficiency of arsenic was 92.36% and 90.53% respectively when the concentration was 506 mg. Kg-1 and 833 mg. Kg-1 respectively. When the arsenic pollution concentration was 2951 mg. Kg-1 5290 mg. Kg-1, the stability efficiency of arsenic was 55.57% and 47.54% respectively. The stability treatment ability of arsenic was limited. (3) bioavailability analysis showed that: Using chemical extraction method and physiological principle extraction method to extract contaminated soil, 3 groups of Available Arsenic in soil and the amount of arsenic in the body are in the order of contaminated soil deionized water > stable agent. Stable treatment can obviously reduce the bioavailability of arsenic in soil, greatly reduce the available arsenic in soil and the arsenic in the body. (4) the results of leaching toxicity analysis showed that the leaching concentration of soil arsenic in 3 groups was contaminated by the national standard method (HJ/T299-2007) and TCLP method. The order of the leaching concentration of arsenic in the soil was contaminated soil deionized water > stable reagent, stable treatment could stabilize and absorb arsenic in soil, and greatly reduced the toxic leaching concentration of arsenic. (5) occurrence form. The results showed that the content of easily soluble arsenic in contaminated soil was reduced by 18.61%, iron type arsenic increased by 10.36% and calcium type arsenic increased by 5.81%. Stable treatment could effectively transform the soluble arsenic in soil into iron type arsenic and calcium type arsenic. (6) the result of phase analysis showed that CaAl2Si2O8. 4H20 (trapezoid calcium boiling) was added to the contaminated soil after stable treatment. Stone), Ca3Fe4+3 (AsO4) 4 (OH) 8. 3H2O (: siderite), Fe2 (AsO4) (SO4) OH. 5H2O (arsenite), (Al, Fe+3) 3AsO4 (arsenopyrite) four minerals, stable treatment can promote the transformation of arsenic in the soil to mineral arsenic. (7) simulated acid rain experiment showed: (1) stable treatment of soil arsenic leaching concentration prolonged with leaching time to maintain Between 0.88mg, L-1 and 1.01 mg / L-1, the concentration of arsenic in contaminated soil is 17.79 mg.L-1 to 7.31mg L-. Stable treatment can effectively control the dissolution of arsenic. 2. The total arsenic in soil is reduced to 9.63%, which is much lower than that of contaminated soil, which is mainly due to the stable treatment of arsenic in soil to produce refractory iron type arsenic and the arsenic in soil. Calcium based arsenic also increased soil buffering capacity and effectively resisted acid rain scouring.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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