聚乙烯醇固定化白腐真菌对复合废水的处理及其机理研究

发布时间：2018-03-04 10:16

本文选题：聚乙烯醇　切入点：黄孢原毛平革菌　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：固定化微生物技术是利用物理或化学手段将具有特定生理功能的游离微生物固定于载体材料内部或表面,并对该固定化微生物加以有效利用的一门技术。该技术具有微生物活性高、单位空间微生物密度高、耐受性好、抗冲击负荷能力强、处理效率高、重复利用率高等优点,目前已在废水处理中得到较为广泛的应用。近年来,废水污染日益严重,污染组分也由单一污染物向多种污染物蔓延,其中,重金属和有机污染物形成的复合污染问题引起研究者们的广泛关注,这主要是因为这两种污染物均为较难去除的有毒物质,它们不仅对水体造成严重污染,还会对人体造成较大危害。聚乙烯醇(polyvinyl alcohol,PVA)具有价格低廉、亲水性好、机械强度高、化学稳定性强、不易被生物分解、无生物毒害性等优点,被广泛作为固定化微生物的载体材料。但是PVA因其黏性和水溶胀性大而对固定化载体的制备产生附聚作用,故本文在PVA载体中加入海藻酸钠、粉末活性炭、二氧化硅、沸石粉等添加剂,以改善PVA的机械性能及其黏连现象。并且利用制备的PVA复合载体固定化白腐真菌的模式菌种——黄孢原毛平革菌,这是因为该菌种对重金属和异生质类污染物均具有较强去除能力。然后,将这种新型的PVA固定化黄孢原毛平革菌用于生物修复复合废水中重金属镉和2,4-二氯酚(2,4-DCP)。本论文全面系统地研究了投加量、接触时间、镉初始浓度和2,4-DCP初始浓度等因素对PVA固定化黄孢原毛平革菌去除重金属镉和降解有机污染物2,4-DCP的影响;考察了吸附降解过程中,溶液中p H值和胞外蛋白含量的变化情况;探究了PVA固定化黄孢原毛平革菌对镉的去除机理和对2,4-DCP的降解机理。本文的具体研究成果为:当复合废水中镉和2,4-DCP的初始浓度分别为20 mg/L和40mg/L时,PVA固定化黄孢原毛平革菌对镉和2,4-DCP的去除效率达到最佳,分别为78%和95.4%,并且其大大改善了黄孢原毛平革菌对镉和2,4-DCP的耐受能力,即使在较高的镉初始浓度条件下,镉的去除率仍在60%以上,在不同2,4-DCP初始浓度条件下,2,4-DCP的降解率均高于90%;一定范围内镉和2,4-DCP初始浓度的增加能促进胞外蛋白的分泌,并对溶液中p H值产生一定的影响;PVA固定化黄孢原毛平革菌可能把低浓度的2,4-DCP作为碳源和能源,把胞外分泌蛋白作为氮源,加以利用,进一步去除废水中镉和2,4-DCP;此外,吸附-脱附实结果表明,PVA固定化黄孢原毛平革菌可重复利用,经3次吸附-脱附过程后,镉的解吸率高达98.9%且去除能力无明显降低,对2,4-DCP也具有较好的降解效果,且该固定化小球保持完整的球状,未出现分解的现象。结合环境扫描电镜(SEM)和X射线光电子能谱(EDAX)分析可知,PVA固定化黄孢原毛平革菌主要借助于固定化材料及其表面形成网状结构的菌丝体吸附镉离子,吸附后的菌丝体变得致密,并在其表面形成泥状物质;傅里叶红外变化光谱(FTIR)的研究结果表明,PVA固定化黄孢原毛平革菌中负责去除重金属镉的主要功能基团有羟基、羧基和氨基;根据气质联用仪(GC-MS)的分析结果,发现2,4-DCP被分解为反丁烯二酸和正己醇等降解产物。综上所述,PVA固定化黄孢原毛平革菌能够同时有效地去除废水中的重金属和有机污染物,为PVA固定化微生物技术在废水领域的普遍应用提供了理论指导。
[Abstract]:Immobilized microorganism technology is free microorganisms by physical or chemical means to have a specific physiological function is fixed on the carrier material or internal surface, and the immobilized microorganism technology to an effective use. This technology has high microbial activity, microbial spatial units, high density, good tolerance, strong anti shock loading capability, high efficiency, high recycling rate advantages, has been widely used in wastewater treatment. In recent years, water pollution is becoming increasingly serious, the pollution components from a single variety of pollutants to the spread of pollutants, the formation of the combined pollution of heavy metals and organic pollutants caused widespread concern of researchers, the main this is because the two pollutants are difficult to remove toxic substances, they are not only the water causing serious pollution, will cause greater harm to the human body. Poly (polyv Inyl alcohol, PVA) has the advantages of low cost, good hydrophilicity, high mechanical strength, chemical stability, easily biodegradable, has no biological toxicity, is widely used as carrier materials of immobilized microorganism. But the PVA because of its viscosity and water swelling and the immobilized carrier preparation generate agglomerate so in this paper, the PVA vector with sodium alginate, powder activated carbon, silica, zeolite powder and other additives to improve the mechanical properties of PVA and its adhesion phenomenon. And the use of immobilized white rot fungus PVA composite carrier preparation mode, fungus Phanerochaete Chrysosporium, this is because the bacteria are has a strong ability to remove heavy metals and xenobiotics pollutants. Then, the new PVA immobilized phanerochaetechrysosporium for bioremediation of heavy metal cadmium in composite wastewater and 2,4- two chlorophenol (2,4-DCP). This paper comprehensively and systematically Study on the dosage, contact time, initial concentration of cadmium factor and the initial concentration of 2,4-DCP and 2,4-DCP heavy metal cadmium removal effect of organic pollutants degradation of PVA immobilized Phanerochaete Chrysosporium; adsorption was investigated in the degradation process, the changes of P H and protein content of the cell in solution; explore the mechanism the removal of PVA immobilized Phanerochaete Chrysosporium on cadmium and 2,4-DCP degradation mechanism. The research results of this paper is: when the initial concentration of cadmium and 2,4-DCP compound in the wastewater were 20 mg/L and 40mg/L, PVA immobilized Phanerochaete Chrysosporium on cadmium removal efficiency 2,4-DCP and achieve the best. Were 78% and 95.4%, and it has greatly improved the Huang Baoyuan Chrysosporium tolerance to cadmium and 2,4-DCP, even in the condition of higher initial concentration of cadmium, cadmium removal rate is still above 60%, at different initial 2,4-DCP concentrations, 2,4-DCP The degradation rates were higher than 90%; the increase in a certain range of cadmium and the initial concentration of 2,4-DCP can promote the secretion of extracellular proteins, and have a certain impact on the solution of P H; PVA immobilized phanerochaetechrysosporium may have low concentrations of 2,4-DCP as carbon and energy sources, the extracellular protein as nitrogen the source, to use, to further remove cadmium and 2,4-DCP in waste water; in addition, adsorption desorption results show that PVA immobilized phanerochaetechrysosporium can be reused after 3 adsorption desorption process, the desorption rate of cadmium was as high as 98.9% and the removal ability decreased obviously, also has the effect of degradation 2,4-DCP well, and the immobilized beads maintain the integrity of the ball, no decomposition phenomenon. Combined with environmental scanning electron microscopy (SEM) and X ray photoelectron spectroscopy (EDAX) analysis shows that PVA immobilized phanerochaetechrysosporium mainly by immobilized material and its surface shape The adsorption of cadmium ion mycelia mesh structure, mycelium after adsorption became dense, and mud material formed on the surface; Fourier transform infrared spectrum changes (FTIR) results show that PVA immobilized phanerochaetechrysosporium responsible for the main function of cadmium removal group with hydroxyl, carboxyl and amino; according to the GC-MS (GC-MS) analysis results, found that 2,4-DCP was decomposed into fumaric acid and hexyl alcohol degradation products. In summary, PVA immobilized Phanerochaete Chrysosporium can effectively remove heavy metals in wastewater and organic pollutants, to provide theoretical guidance for the universal application of immobilized microorganism technology PVA in the field of wastewater.

【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;X172

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