【作者】 费文砚；

【导师】 吴涓；

【作者基本信息】 安徽大学 ， 环境科学， 2007， 硕士

【摘要】 传统的絮凝剂具有价格低，絮凝效果好等优点，但存在一些缺点如：饮用水中残留的铝易导致老年痴呆症；聚丙烯酰胺类絮凝剂单体对人体有毒害作用，易引发癌症等。因此，开发安全无毒、高效的、无二次污染的新型环保絮凝剂，对相关水处理工艺和生产工艺的改进、人类健康和环境保护都有着很重要的现试意义。20世纪80年代后期，随着生物技术的发展，一类新型的水处理剂—微生物絮凝剂应运而生，对它的研究也越来越受到国内外的关注。本文从土壤中选能产生微生物絮凝剂产生菌，并在此基础上对微生物絮凝剂的絮凝特性、机理和应用等展开初步研究。从土壤中筛选出了8株具有絮凝活性的菌株，经复筛后得到2株絮凝活性较高的微生物絮凝剂产生菌，命名为C1和C5。以C1和C5为研究对象，分别考察了培养基中碳源、氮源、无机盐以及培养基初始pH值和培养温度等理化因素对絮凝活性的影响。研究结果表明，C1菌株产絮凝剂的最适条件为：分别以浓度为2％的葡萄糖和0.2％的牛肉膏为最适碳源和氮源，其他条件：初始pH6.0，培养温度30℃，培养时间为72h。所产絮凝剂对0.4％高岭土悬浊液的絮凝效率可达90.4％；C5菌株的最适培养基为：以浓度为1％的葡萄糖和0.2％的谷氨酸为最适碳源和氮源，初始pH 7.5，培养温度36℃，培养时间为72 h。所产絮凝剂对0.4％高岭土悬浊液的絮凝效率可达92.0％，显示出良好的应用前景。通过正交实验确定C1菌株的最适絮凝条件为：发酵液投加量2.0mL，絮凝时pH 7.0，CaCl₂溶液的投加量为4.0ml，静置时间为60min；确定的C5菌株的最适絮凝条件为：发酵液投加量2.5 mL，絮凝时pH 6.0，CaCl₂溶液投加量为5mL，静置时间为100min。利用丙酮提取法，从发酵液中提取絮凝剂，并研究了其主要成分。通过苯酚—硫酸法、茚三酮反应确定微生物C1所产絮凝剂主要成分为多糖，C5所产絮凝剂主要成分为多糖和蛋白质。这两种絮凝剂对生物染料次甲基兰的脱色率可达98.5％和99.0％，其良好脱色性能使絮凝剂具有广阔的应用前景。并通过优化实验，确定了最适脱色条件。为了降低微生物絮凝剂的生产成本，以发酵培养基为基础，采用其他一些物质作为菌株培养的替代碳源、氮源。实验结果显示，用乙醇作为碳源时，C1和C5的絮凝活性分别达到84.4％和82.8％；以豆饼、黄豆粉和豆芽汁分别替代酵母膏作为C1的氮源后，絮凝活性分别为83.0％、84.1％和83.0％；当C5的氮源为豆芽汁后絮凝活性为81.8％，效果均优于使用酵母膏。更多还原

【Abstract】 Organic and inorganic flocculants have been used widely due to their low pricesand good effect. However, their disadvantages have drawn people’s attention.Aluminium remaining in drinking water easily leads to senile dementia. Themonomer of polyacrylamide can’t be degraded and it’s both neurotoxic andoncogenic for human body. Microbial flocculants are safe and biodegradablemacromolecular flocculants secreted by microorganisms. Their degradation productsare harmless to the ecosystem and humans. The development of a new biodegradablebioflocculant with strong flocculating activity is attracting wide research interest.Therefore, researchers are showing a growing concern on the development of MBF.Eight strains of microbial flocculant-producing microorganisms are isolatedfrom soil. After rescreening, Two strain named C1 and C5 with high and stableflocculating activity is obtained. The factors affecting the production andflocculating activity of microbial flocculant, such as carbon sources, nitrogensources, complex nitrogen sources, inorganic salts, initial pH value and culturetemperature are investigated. The results of C1 indicates that the optimum carbonsources, nitrogen sources, initial pH value and culture temperature are 2% glucose,0.2% beef extract, pH 6.0 and 30℃, respectively. The strain of C1 produces a highactivity flocculant, with flocculating rate of 90.4% against 0.4% kaolin claysuspension under the optimum cultural conditions. The results of C5 indicated that the optimum carbon sources, nitrogen sources, initial pH value and culturetemperature are 1% glucose, 0.2% glutamic acid, pH 7.5 and 36℃. The strain of C5produced a high activity flocculant, with flocculating rate of 92.0% against 0.4%kaolin clay suspension under the optimum cultural conditions.Through orthogonal test of C1, the optimal flocculating conditions are found tobe: 2.0 mL of microbial flocculant dosage, pH7.0, 4mL of 1% CaCl₂ and 60 min ofsettling time. Through the orthogonal test of C5, the optimal flocculating conditionsare found to be: 2.5 mL of microbial flocculant dosage, pH6.0, 5 mL of 1% CaCl₂and 100 min of settling time.The flocculants are extracted from culture broth using acetone solvent. Theflocculants of C1 is mainly composed of amylose. The flocculants of C5 is mainlycomposed of amylose and protein. That is determined by Phenol-Sulfuric acidreaction and Ninhydrin reaction. The flocculants has heat stability. Thedecolorization rate of Methylene Blue by the treatment of microbial flocculantsachieve to 98.5% and 99.0%. It has good flocculating effect on decoloring and claysuspension. And through following test, the optimal technologic conditions arefound. The results show that the flocculating mechanism resulted from thecombination of protein with kaolin clay by bridge at the active position of theflocculation and charge effect neutralization.In order to decrease the cost of microbial flocculant, the cheap substitutive ofethanol for carbon source are developed for C1 and C5, which are based on fermentmedium. The flocculanting activities are up to 84.4% and 82.8%. The optimumsubstitutive mediums of C1 for nitrogen source are bean cake、soybean powder andbean sprout extract. The flocculanting activity are 83.0%、84.1% and 83.0%. Theoptimum substitutive medium of C5 for nitrogen source is bean sprout extract. Theflocculanting activity achieves to 81.8%.更多还原