【作者】 朱丹；

【导师】 冯贵颖；

【作者基本信息】 西北农林科技大学 ， 环境工程， 2006， 硕士

【摘要】 絮凝技术被广泛应用于给水、废水净化,污泥脱水处理中,其絮凝效果主要取决于絮凝剂种类。微生物絮凝剂是一类由微生物产生的代谢产物,主要成分有多糖、糖蛋白、蛋白质、纤维素和DNA等。作为一种新型的水处理剂,它不仅避免了无机、有机高分子絮凝剂的大量使用对环境和人类健康造成的危害,更具有高效、无毒、无二次污染的特点,对多种工业废水都有良好的净化效果,有着广泛的应用前景,因此受到各国研究者的重视。本论文在系统地论述近年来国内外微生物絮凝剂的研制开发现状与发展的基础上,对微生物絮凝剂产生菌种筛选、培养条件优化、微生物絮凝剂的絮凝特性以及应用,进行了研究与探讨,主要内容与所得结论如下:(1)本试验以校园绿地土壤和陕西杨凌植化工程中心排水口污泥作为菌源,在特定的培养基中培养增殖,平板涂布得到单菌。以高岭土为测试对象,对获得的单菌株絮凝活性进行测定、筛选絮凝剂产生菌。在筛选得到的21株菌中,发现其中一株来源于土壤的菌株具有较强的絮凝活性,初步鉴定为细菌/芽孢杆菌科/芽孢杆菌属,并命名为Bacillus BC—11。(2)为了最大限度地提高絮凝剂的絮凝活性,在筛选培养基的基础上,对培养基的组成及培养条件进行了优化。在优化后的培养条件下,絮凝剂产生菌能够在细胞内合成絮凝剂并分泌到胞外,生成具有絮凝活性的粘性微生物絮凝剂。(3)对得到的产絮凝剂微生物的生长曲线进行研究发现,菌Bacillus BC—11在生长的同时产生并积累絮凝剂,将其分泌到细胞外,起絮凝作用的物质主要存在于发酵液中。(4)为了降低生产成本,采用皂素废水作为替代培养基。在添加0.1%的NaNO3作为外加氮源和0.8%的KH2PO4,调节培养基pH值为7的条件下,对菌Bacillus BC—11进行培养,可以获得廉价的絮凝剂,培养得到絮凝剂的絮凝活性能达到82.57%,说明制药废水也能够做为替代培养基培养产絮凝剂微生物。(5)应用研究结果表明,由菌Bacillus BC—11产生的絮凝剂,对土壤悬浊液,造纸废水,生活废水和水性油墨废水都有良好的处理效果。尤其是对以射光蓝废水为代表的水性油墨废水的处理效果最佳,其处理效果优于传统使用的无机絮凝剂。对水性油墨废水的处理方法国内外目前还鲜见报道。更多还原

【Abstract】 Flocculants are widely used in wastewater treatment. The flocculating activity has big deal with the type of flocculants. Micorbial flocculants are newly developed natural macromolecular organic substance, which have the ability to flocculate various wastewater. For their biodegradability, high performance and harmlessness to the environment, microbial flocculants have drowned more and more attention, and become the front line of investigation. This paper summarized a series of basic research and development om preparation of microbial flocculants. This isolation of flocculant-producing bacterium from active sludge and soil, optimization of culture condition for flocculant production, pilot-scale, the composition, characteristic and flocculation mechanism of the microbial flocculants were studied and discussed systematically. The main centents of research and the results are as follows:(1) For the screening of microbial flocculant-producing microorganism, suspensions from sludge and soil solution were cultivated in given media with Kaolin clay suspension as the test sample for flocculating activity. A flocculant-producinbg bacterium isolated from soil was identified as Bacillus BC—11.(2) Culture medium and conditions for flocculant production were optimized on the basis of original screening culture medium. Under the optimal culture conditions, Bacillus BC—11 synthesized intracellularly and excreted extracellularly viscous flocculant immediately.(3) Under the research of growth curve of Bacillus BC—11, the flocculating substances synthesized intracellularly which mainly existed in ferment liquid.(4) In order to reduce the cost of media, the strain Bacillus BC—11 was cultured in wastewater of yam samponin. The results showed that the strain Bacillus BC—11 could grow and reproduce well, which provided technical and economic feasibility for further production of microbial flocculant on pilot-scale.(5) The results of application studies indicated that the microbial flocculant produced by Bacillus BC—11 had the ability to flocculate various simulating wastewater and practical wastewater well, especially on the reflex blue wastewater.更多还原