胶质芽孢杆菌微生物絮凝剂的制备及对含重金属污水的处理研究

发布时间：2018-06-07 12:00

  本文选题：微生物絮凝剂 + 分离鉴定　； 参考：《长安大学》2015年硕士论文

【摘要】：微生物絮凝剂(MBF)是一类由微生物产生的具有絮凝活性的物质,主要化学成分是糖蛋白、多糖、蛋白质、纤维素、核酸等大分子物质,因其特定的结构和组成而形成了良好的絮凝沉淀性能。与传统絮凝剂相比,微生物絮凝剂具有安全、无毒、可生物降解、无二次污染的优点,是具有生物分解性和安全性的水处理剂,在给水处理、城市生活污水处理、食品加工、发酵、化工、畜牧、建材等行业废水处理等方面的具有广泛的应用前景。胶质芽胞杆菌与其他微生物絮凝剂产生菌株相比,发酵培养不需要氮源,对营养条件要求低、容易培养和鉴别,在很大程度上降低了其生产成本,因而具有较高的实际应用价值。本文采用选择性无氮培养基从土样及造纸厂活性污泥样品中筛选分离得到90株菌株,采用高岭土悬浮液测定絮凝活性的方法进行复筛,得到一株菌落边缘整齐、粘稠、挑起时有拉丝、弹性大且效絮凝活性大于90%的絮凝剂产生菌MY6-2。结合形态学、生理生化分析及16SrDNA分析,鉴定该菌株为胶质芽孢杆菌(Baccillus mucilaginous)。采用单因素及响应面等方法优化菌株MY6-2发酵培养基及培养条件,以提高其絮凝剂产量及絮凝活性。通过对二次多项线性回归方程及响应面图分析可知,该菌最佳发酵培养基配方为:0.5%蔗糖,不需要氮源;最佳培养条件:装液量约100mL/250mL三角瓶、初始pH 8、接种量为10%。在此条件下,胶质芽孢杆菌MY6-2絮凝活性为:絮凝剂用量为0.5mL发酵液/100mL高岭土时,絮凝率约为90%。通过对其絮凝物质进行提取并且对其成分进行分析,结果发现:该絮凝物质主要分布在发酵液中。利用醇沉法提取絮凝物质,冻干后得到白色粉状固体。通过物理、化学等方法分析知该物质主要为多糖类物质,具有良好的热稳定性。絮凝特性研究结果表明,絮凝剂使用条件为:pH7,助凝离子为3mL Ca2+/100 mL高岭土,絮凝剂用量为0.1mg/100mL高岭土,其絮凝活性90%;初步的应用实验结果表明该絮凝剂对黄土、活性炭、膨润土、硅藻土等几种常见悬浮体系均具有良好的絮凝效果。采用单因素试验对胶质芽孢杆菌MY6-2絮凝剂吸附铁离子的特性进行了研究。结果表明:絮凝体系pH为5,絮凝剂用量为6 mL,温度为30℃,铁离子浓度为60 mg/L至800 mg/L时,MY6-2絮凝剂铁离子的吸附絮凝率均大于90%以上。
[Abstract]:Microbial flocculant (MBF) is a class of flocculating substances produced by microbes. The main chemical components are glycoprotein, polysaccharide, protein, cellulose, nucleic acid and other macromolecular substances. Because of its specific structure and composition, good flocculation and precipitation performance has been formed. Compared with traditional flocculants, microbial flocculants have the advantages of safety, non-toxicity, biodegradability and no secondary pollution. They are biodegradable and safe water treatment agents, such as water treatment, municipal sewage treatment, food processing, etc. Fermentation, chemical, animal husbandry, building materials and other industries wastewater treatment has a wide range of applications. Compared with other microbial flocculant producing strains, the fermentation culture of Bacillus glia does not require nitrogen source, and requires less nutrition conditions, so it is easy to be cultured and identified, which greatly reduces the production cost. Therefore, it has high practical application value. In this paper, 90 strains were isolated from soil samples and activated sludge samples of paper mill by selective nitrogen-free medium. The flocculation activity was determined by kaolin suspension. The flocculant producing strain MY6-2 with high elasticity and more than 90% flocculant activity. Combined with morphological, physiological and biochemical analysis and 16SrDNA analysis, the strain was identified as Baccillus mucilaginousus. Single factor and response surface were used to optimize the fermentation medium and culture conditions of the strain MY6-2 in order to improve its flocculant yield and flocculation activity. By analyzing the quadratic linear regression equation and response surface diagram, we can know that the optimum fermentation medium of the strain is: 0.5% sucrose without nitrogen source, and the optimum culture conditions are: the volume of liquid is about 100mL/250mL triangle bottle, the initial pH is 8, and the inoculation amount is 10. Under these conditions, the flocculation activity of Bacillus glia MY6-2 is as follows: when the dosage of flocculant is 0.5mL fermentation broth / 100ml kaolin, the flocculation rate is about 90%. The results showed that the flocculant was mainly distributed in fermentation broth. The flocculant was extracted by alcohol precipitation, and the white powder solid was obtained after freeze-drying. Through physical and chemical analysis, it was found that the substance was mainly polysaccharide and had good thermal stability. The results showed that the flocculant was used under the conditions of: pH7, 3mL Ca2 / 100ml kaolinite and 0.1mg/100mL kaolin. The preliminary application results showed that the flocculant was applied to loess, activated carbon and bentonite. Several common suspensions such as diatomite have good flocculation effect. The adsorption of iron ions by MY6-2 flocculants of Bacillus glia was studied by single factor test. The results showed that the adsorption flocculation rate of the flocculant was more than 90% when pH was 5, the dosage of flocculant was 6 mL, the temperature was 30 鈩，

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