铁尾矿土壤化利用及重金属污染的微生物修复技术
发布时间：2018-10-16 13:10
【摘要】：铁矿的采选不仅造成大量固体废物的排放和堆存,而且选矿药剂和重金属污染还会通过不同方式进入大气、水体和土壤中,造成严重的环境污染。因此铁尾矿的土壤化、资源化利用不仅是突破铁矿产业环境瓶颈的重要措施,而且可以解决矿山修复过程中土壤资源不足的问题。本研究可为微生物技术修复土壤中的重金属污染提供理论基础,具有极为重要的应用价值。传统的修复重金属污染的铁尾矿的方法根据原理可分为化学法、物理法和生物法。化学法使用的添加剂会导致土壤的二次污染,而物理修复技术成本高,流程及设备操作复杂。生物修复技术绿色环保且不会产生二次污染,在重金属污染修复领域展现了广阔的应用前景,近年来逐渐成为污染土壤原位修复的首选技术。本文针对鞍山铁尾矿重金属污染的实际状况,筛选出了耐受Pb、Mn和Zn的土著菌种,并优化修复作用条件以提高修复效率,然后研究其在铁尾矿土壤化利用过程中的应用,有效改善铁尾矿肥力,提高铁尾矿利用效率。主要研究内容和结论如下:通过富集培养技术,对铁尾矿样品进行驯化后,获得了能够耐受Pb、Mn和Zn重金属污染的菌种。对菌种的内转录区间经过扩增后比对,分别绘制各菌种的系统进化树。三种菌种分别为能够耐受Pb污染的土著菌种-卷枝毛霉,耐受Mn污染的土著菌种-棘孢木霉,耐受Zn污染的土著菌种-被孢霉,三种菌种在液体培养基中培养12h后基本达到对数生长期,生物学特征明显,对重金属污染具有较强的耐受能力,同时能很好地适应环境,为重金属污染铁尾矿的微生物修复提供了技术支持。通过吸附实验,以三种真菌活化后的菌丝作为吸附剂,分别用卷枝毛霉吸附Pb2+,棘孢木霉吸附Mn2+,被孢霉吸附Zn2+,分别考察了温度、pH和初始接种量对各菌种吸附效果的影响。结果表明卷枝毛霉对Pb2+和棘孢木霉对Mn2+的吸附作用最佳pH为6,被孢霉对Zn2+的最佳pH为7;卷枝毛霉对Pb2+、被孢霉对Zn2+吸附作用的最佳温度都为26℃,而棘孢木霉对Mn2+的吸附作用的最佳温度为28℃;卷枝毛霉和棘孢木霉分别对Pb2+和Mn2+的吸附率在初始接种量为1.0ml的时达到最大值,而在初始接种量为1.2ml的条件下被孢酶对Zn2+的吸附率最大。在初始重金属离子浓度设置为20mg/L时,卷枝毛霉菌种对Pb2+、棘孢木霉菌种对Mn2+以及被孢霉菌种对Zn2+的吸附率分别达到了 95.46%、92.78%和86.89%。三种菌种都可以很好的吸附溶液中的重金属离子,吸附能力最强的为卷枝毛霉,其次是棘孢木霉,最小的是被孢霉。通过吸附实验,分别研究了最佳实验条件下卷枝毛霉菌种对Pb2+、棘孢木霉菌种对Mn2+以及被孢霉菌种对Zn2+的吸附热力学和动力学曲线,发现Langmuir型等温吸附模型可以用于拟合三种菌种分别对重金属离子的吸附作用过程,并且根据公式算得的卷枝毛霉对Pb2+、棘孢木霉对Mn2+、被孢霉对Zn2+的最大吸附量分别为79.76、76.42和78.16 mg/g,R2分别为0.9932、0.9693和0.9759,比较R2可知,卷枝毛霉对Pb2+的亲和力大于另外两种菌种的亲和力。将卷枝毛霉对Pb2+、棘孢木霉对Mn2+、被孢霉对Zn2+的吸附曲线分别进行拟合发现,拟合曲线符合伪二级动力学模型,说明菌种主要通过离子交换和络合等反应吸附重金属,卷枝毛霉对Pb2+,棘孢木霉对Mn2+以及被孢霉对Zn2+的最大吸附量分别为77.42、75.00和68.57 mg/g;R2分别为0.9991、0.9192和0.9844,卷枝毛霉对Pb2+的吸附曲线拟合效果较好,三种菌种对重金属吸附量都较高,说明它们在重金属污染铁尾矿的原位修复中具有较高的应用潜力。通过现场应用研究,分析混合菌剂对铁尾矿中重金属可交换态、酶活性以及微生物多样性的影响。将菌种混合培养后制成微生物菌剂,应用到铁尾矿土壤化利用的过程中。结果表明,实验室微生物菌剂对重金属具有较好的固定作用,固定效率分别为74.98%(Zn)、85.29%(Pb)和79.41%(Mn),微生物菌剂的添加使得铁尾矿中的微生物数量增加(p0.05),其中细菌、真菌和放线菌的数量分别比施加菌剂前分别增加了 16.81%、34.62%和27.63%。同时经微生物菌剂处理的铁尾矿过氧化氢酶和脲酶的活性比施加菌剂前分别增加了 68.79%和56.47%,说明随着铁尾矿中重金属可交换态的含量的降低对酶活性的抑制作用减弱,且微生物数量与酶活呈显著相关。铁尾矿的微生物多样性指数(Shannon-Wiener指数)由3.7增加到了 4.05,说明微生物菌剂的添加对铁尾矿中微生物的多样性有促进作用,有效改良了铁尾矿的生物群落结构,促进了铁尾矿中微生物的生长和繁殖(p0.05)。
[Abstract]:The selection of iron ore not only leads to the discharge and pollution of large quantities of solid waste, but also the ore dressing agent and heavy metal pollution can enter the atmosphere, water and soil in different ways, causing serious environmental pollution. Therefore, the soil treatment and resource utilization of iron tailings is not only an important measure to break through the environmental bottleneck of iron ore industry, but also can solve the problem of insufficient soil resources in mine tailings. This study can provide a theoretical basis for the remediation of heavy metal pollution in soil by microbial technology, and it has extremely important application value. The traditional method for repairing heavy metal contaminated iron tailings can be divided into chemical, physical and biological methods according to the principle. The additive used in the chemical method can lead to secondary pollution of the soil, and the physical repair technology has high cost, and the flow and equipment operation is complicated. The bioremediation technology is green and environment-friendly and does not generate secondary pollution, has a wide application prospect in the field of heavy metal pollution remediation, and gradually becomes the preferred technology for in-situ remediation of polluted soil in recent years. In the light of the actual situation of heavy metal pollution in iron tailings tailings, this paper selects indigenous strains tolerant of Pb, Mn and Zn, and optimizes the repair conditions to improve the efficiency of remediation, and then studies its application in the process of soil utilization of iron tailings, and effectively improves the fertility of iron tailings. and the utilization efficiency of the iron tailings is improved. The main research contents and conclusions are as follows: After acclimation of iron tailings samples by enrichment culture technique, strains which can tolerate heavy metal pollution of Pb, Mn and Zn are obtained. The internal transcribed region of the strain is amplified and compared with each other, and the phylogenetic tree of each strain is respectively drawn. The three strains are indigenous strains capable of tolerating Pb pollution, chaetchaete chrysosporium, indigenous strains resistant to Mn pollution, and indigenous species-Mortierella sp. which are tolerant of Zn pollution, and three strains are cultured in a liquid culture medium for 12h to basically reach logarithmic growth phase, and the biological characteristics are obvious. has strong tolerance to heavy metal pollution, can well adapt to the environment, and provides technical support for bioremediation of heavy metal contaminated iron tailings. The effects of temperature, pH and initial inoculum on the adsorption of strains were studied by adsorption experiments and adsorption of the mycelium of three kinds of fungi as adsorbent. The results showed that the optimum pH of the adsorption of M _ 2 + was 6, the optimum pH was 7, the optimum pH was 26 鈩，
本文编号：2274466
[Abstract]:The selection of iron ore not only leads to the discharge and pollution of large quantities of solid waste, but also the ore dressing agent and heavy metal pollution can enter the atmosphere, water and soil in different ways, causing serious environmental pollution. Therefore, the soil treatment and resource utilization of iron tailings is not only an important measure to break through the environmental bottleneck of iron ore industry, but also can solve the problem of insufficient soil resources in mine tailings. This study can provide a theoretical basis for the remediation of heavy metal pollution in soil by microbial technology, and it has extremely important application value. The traditional method for repairing heavy metal contaminated iron tailings can be divided into chemical, physical and biological methods according to the principle. The additive used in the chemical method can lead to secondary pollution of the soil, and the physical repair technology has high cost, and the flow and equipment operation is complicated. The bioremediation technology is green and environment-friendly and does not generate secondary pollution, has a wide application prospect in the field of heavy metal pollution remediation, and gradually becomes the preferred technology for in-situ remediation of polluted soil in recent years. In the light of the actual situation of heavy metal pollution in iron tailings tailings, this paper selects indigenous strains tolerant of Pb, Mn and Zn, and optimizes the repair conditions to improve the efficiency of remediation, and then studies its application in the process of soil utilization of iron tailings, and effectively improves the fertility of iron tailings. and the utilization efficiency of the iron tailings is improved. The main research contents and conclusions are as follows: After acclimation of iron tailings samples by enrichment culture technique, strains which can tolerate heavy metal pollution of Pb, Mn and Zn are obtained. The internal transcribed region of the strain is amplified and compared with each other, and the phylogenetic tree of each strain is respectively drawn. The three strains are indigenous strains capable of tolerating Pb pollution, chaetchaete chrysosporium, indigenous strains resistant to Mn pollution, and indigenous species-Mortierella sp. which are tolerant of Zn pollution, and three strains are cultured in a liquid culture medium for 12h to basically reach logarithmic growth phase, and the biological characteristics are obvious. has strong tolerance to heavy metal pollution, can well adapt to the environment, and provides technical support for bioremediation of heavy metal contaminated iron tailings. The effects of temperature, pH and initial inoculum on the adsorption of strains were studied by adsorption experiments and adsorption of the mycelium of three kinds of fungi as adsorbent. The results showed that the optimum pH of the adsorption of M _ 2 + was 6, the optimum pH was 7, the optimum pH was 26 鈩，
本文编号：2274466
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