生物炭与微生物联合修复金尾矿的汞砷污染
文献类型：学位论文
| 作者 | 魏永洋 |
| 答辩日期 | 2017-05-01 |
| 文献子类 | 硕士 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 新疆乌鲁木齐 |
| 导师 | 潘响亮 |
| 关键词 | 生物炭 金矿尾矿 尿素分解菌 MICP 汞 砷 Biochar Gold mine tailing Staphylococcus succinus MICP Hg2+ As3+ |
| 学位专业 | 理学硕士 |
| 英文摘要 | Xinjiang is rich in mineral resources and large in number of gold mines. The productof gold mining tailings has a huge amount, in which has high concentration of Hg2+ andAs3+. The open-air stacking lead to the migration of Hg2+ and As3+ with rain and snow, thatcaused serious environmental pollution and posed a threat to the ecosystem and humanhealth.However, there are few methods for handling tailings at present. Generally, it isopen-air stacking and has not been dealt with, which has a serious impact on the ecologicalenvironment. There are also few tailings dealt with cement, but which is expensive and isnot conducive to the reuse of tailings. In order to solve this situation, the research teamdeveloped new MICP technology to solidification tailings and was applied it to thesolidification experiments under laboratory conditions. But the effect of tailingssolidification is not ideal, mainly as follows: the unconfined compressive strength is nothigh, and the control effect of some heavy metals needs to be improved. Therefore, thisstudy is expected to enhance the effect of tailings solidification by biochar. Biochar is aneco-friendly material which has a good adsorption effect on heavy metals. We expect theaddition of biochar to enhance the strength of the curing and the effective control of theleaching of heavy metals. In this paper, cotton straw biochar as the material, the biological and physicalproperties of biochar were studied. The adsorption properties of biochar on mercury andarsenic under different conditions also were studied. The thermodynamic process ofmercury adsorption by biochar was investigated by isothermal titration calorimetry (ITC). In combination with the special saline-alkali environment in Xinjiang and the high contentof heavy metals in tailings, bacteria with the ability of urea decomposition and tolerance toheavy metals were isolated. The ability of this bacterium to induce calcium carbonate andthe removal of mercury and arsenic by calcification were investigated. Finally, under theoptimum solidification conditions, biochar was added into the tailings to study the effect of biochar on the control of heavy metal pollution by MICP tailings. The main conclusions ofthis study are as follows:(1)Biochar has abundant pore structure, large surface area and negative charge. Salinity has some effects on biochar adsorption of mercury and arsenic. Biochar has highadsorption capacity of Hg2+ at pH 5 and the maximum adsorption capacity was 5.81 mg/g. The adsorption capacity of biochar of 10 mg/L Hg2+ was up to 4.26 mg/g at 5 ‰ saltconcentration. Solution pH influenced the morphology of As solution, adsorption capacityof biochar on As3+ was up to a maximum of 2.76 mg/g at pH 7. The effect of salinity on theremoval of arsenic by biochar was not obvious, maximum adsorption capacity was 2.60mg/g at 5 mg/L As3+. (2) A thermodynamic study on the adsorption of mercury by biochar using a newSIITC method. At the initial stage it was surface adsorption process, that can be simulatedwith linear model. After that was surface adsorption and particle diffusion process and thenwas particle diffusion process which can be simulated with linear model. Proton adsorptionexperiment proved the particle diffusion process. The whole adsorption process of Hg2+ was available of index equation fitting. (3) A strain Staphylococcus succinus with high urea decomposition ability and acertain tolerance to heavy metals was isolated. Using SIITC technology to study thetolerance of S. succinus to heavy metals, and SIITC is a microbial detection method whichcan be applied to other heavy metals contaminated by other factors. (4) S. succinus bacteria had the ability of calcification and could produce CalciumCarbonate Granules. In the process of MICP had good removal effect of Hg2+, As3+ andremoval rate were more than 90%. The addition of humic acid had no obvious effect on thecalcification process. (5)Through different screening conditions, final optimum solidification conditionswere OD600=0.7, 4% urea and 40 mM calcium chloride. 2.5% biochar was the optimaldosage. The irregular calcium carbonate crystals were formed after solidification of thetailings. The calcium carbonate crystals connected the tailings particles and biochar particles together, thereby enhancing the curing effect. The content of heavy metals in theleachate of the samples decreased with the increase of the amount of biochar, theexchangeable state of the heavy metals decreased, and the binding state of the carbonatebound and Fe-Mn oxides bound were increased. The process of freezing and thawingreduced the curing effect of tailings, and the compressive strength decreased with theincrease of freeze-thaw cycles. |
| 学科主题 | 环境科学 |
| 语种 | 中文 |
| 源URL | [http://ir.xjlas.org/handle/365004/14906]  |
| 专题 | 新疆生态与地理研究所_研究系统_荒漠环境研究室 |
| 作者单位 | 中国科学院新疆生态与地理研究所 |
| 推荐引用方式 GB/T 7714 | 魏永洋. 生物炭与微生物联合修复金尾矿的汞砷污染[D]. 新疆乌鲁木齐. 中国科学院大学. 2017. |
入库方式： OAI收割
来源：新疆生态与地理研究所
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