【作者】 于霞；

【导师】 柴立元；

【作者基本信息】 中南大学 ， 有色金属冶金， 2002， 硕士

【摘要】 细胞固定化技术是一种很有发展前景的废水处理技术。本文以少孢根霉作为首选生物，以含铅废水作为研究对象，对细胞固定化技术处理重金属废水的工艺过程和基础理论进行了系统研究，其主要内容如下： 研究了毛霉目真菌少孢根霉的生长繁殖规律，考察了培养温度、培养基的pH值对其生长的影响。首次开发了一种新型的少孢根霉培养方法——马铃薯切片培养，该方法操作简单，省时省力，少孢根霉生长迅速，生长速率常数为0.1685h^-1，远大于在马铃薯浸汁培养基上的生长速率常数0.1433h^-1：而且降低了成本，可以用来进行少孢根霉的大规模培养。 比较研究了三种细胞固定化载体的诸多性质——传质速度、机械强度、耐酸碱性等，根据这些性质的比较，选择了由包埋剂海藻酸钠与交联剂CaCl₂交联所得的海藻酸钙凝胶作为细胞固定化载体；由其包埋非活性少孢根霉细胞制得的生物吸附剂具有一定的机械强度，传质性能良好，能够耐受一定的pH值。在此基础上对细胞固定化技术的制备工艺条件进行了选择与优化，分别考察了包埋剂浓度，交联剂浓度以及交联时间对吸附剂性质的影响，获得了最佳工艺条件：包埋剂海藻酸钠浓度4％，交联剂CaCl₂浓度3％，交联时间24小时。Langmuir吸附等温模型的计算结果表明固定化少孢根霉对铅离子的最大吸附量为42.918mgPb（Ⅱ）／g吸附剂。 研究了固定化少孢根霉处理含铅废水工艺过程中几种主要理化参数对吸附效果的影响。pH选择在2—5之间，温度以室温为宜：共存离子会使生物吸附剂对铅离子的吸附量下降，其中以铜离子的影响最大。 对生物吸附动力学进行了初步研究。悬浮非活性少孢根霉吸附水溶液中铅离子的动力学过程可以用班厄姆吸附速率方程来描述，当初始铅离子浓度为200mg／L时，吸附速率常数k为0.8775min^-1；而固定化少孢根霉生物吸附剂吸附铅离子的过程受颗粒扩散步骤控制，铅离子在以海藻酸钙作为载体的细胞固定化小球中的粒内扩散系数D_e为1.31×10^-10m²／s。利用红外光谱对少孢根霉吸附铅离子的机理进行了分析，结果表明：少孢根霉吸附铅的主要部位为脱乙酰几丁质上的氨基，铅离子与氮原子的未共用电子对结合。 对铅离子的解吸，固定化少孢根霉的再生、循环及动态吸附进行了详细的研究。选择0.3mol／L柠檬酸作为解吸剂，解吸时间3小时，解吸率可以达到98％以上。用K⁺、Ca²⁺、Mg²⁺浓度均为0.01 mol／L的混合溶液对生物吸附剂进行再生，中南大学硕士论文 摘 要是一种有效的再主方法，经过五次吸附一解吸一再生的循环，固定化少抱根霉仍然可以保持较高的吸附能力和良好的机械性能。在此基础上使用自行设计的动态吸附装置对固定化少抱根霉对铅离子的动态吸附进行了研究，得到其动态饱和吸附量为 48 mg Ph川)／g吸附剂。研究结果为细胞固定化技术处理重金属废水实现工业化提供了重要的基础数据。更多还原

【Abstract】 Fundamental and technological studies on treatment of lead-bearing wastewater by immobilized Rhizopus oligosporus were carried on. The main subjects in this dissertation are as follows.Factors affecting growth and propagation of Rhizopus oligosporus, temperature and pH value, were discussed. A new cultivation was developed, which offers several advantages over traditional cultivation, such as simple operation, time saving and low cost. Rhizopus oligosporus grows fast on the new culture medium, with the growth rate constant being 0.1685 h-1, and a large-scale culture can be proceeded.The characteristics of three gelatinous materials, namely calcium alginate, zinc alginate and aluminum alginate were evaluated for immobilizing biomass of the common mycete, Rhizopus oligosporus. And calcium alginate was found to be the most ideal matrix. The microbeads in which nonliving Rhizopus oligosporus cells were immobilized possess favorable properties with a potential for industrial use, such as adsorption rate, mechanical property and endurance for acid and base. The optimized conditions for preparing biosorbents based on the immobilization of nonliving Rhizopus oligosporus were obtained, i.e., the concentration of imbedding agent sodium alginate is 4%, the concentration of cross-linker CaCb is 3% and the time of cross linkage is 24 hours. Application of the Langmuir isotherm to the system yields the maximum sorption capacity of 42.918 mg Pb( II ) per gram biosorbent.Basic physicochemical parameters, significantly influencing bioremoval of Pb( II ), such as pH value, temperature and interfering cations, were investigated. The results show that the process can be proceeded at room temperature, with the pH value being controlled in the range of 2-5. The immobilized Rhizopus oligosporus accumulates less Pb( II ) when interfering cations exist in the lead-bearing wastewater, and the copper ion has the obvious effect on decreasingthe adsorption amount of Pb( II ) by the biosorbent.The kinetics on biosorption of Pb( II ) by immobilized Rhizopus oligosporus was studied. An initial rapid step of lead binding to Rhizopus oligosporus cell walls is followed by a subsequent slow phase of ions diffusion in the microbeads. The processfor adsorbing Pb(II ) to suspended cells can be described by Bangham model. At initial Pb( II ) concentration of 200 mg / L the adsorption rate constant was calculated to be 0.8775 min-1 according to the model. The diffusion of lead ion in the pellet is intrapartically controlled and the transfer coefficient De was assessed to be 1.31 X 10"10 m2/s. By analyzing the IR spectrograms of several pretreated biomass, the main mechanism on accumulation of Pb( II ) by nonliving Rhizopus oligosporus cells was regarded as chelation between metal cations and amino groups of chitoson.Immobilized systems are well suit for non-destructive recycling. Elution by citrate acid of 0.3 mol / L was found to be the best for Pb(II) desorption over 98%. The biosorbed immobilization Rhizopus oligosporus was regenerated by contacting with a solution containing 0.01 mol / L K\ Ca2+ and Mg2+ ions before further adsorption. With five cycles of biosorption-elution-regeneration the microbeads still keep high lead biosorption capacity. In addition, a series of flow studies was carried out using columns containing biosorbents. The results indicated that the saturation biosorption capacity reaches 48 mg Pb( II ) per gram biosorbent. The study provides an important base for the commercial application of the immobilized nonliving Rhizopus oligosporus in the removal of lead ions from wastewater.更多还原