磁粉对生物法处理重金属废水影响的研究

【作者】 涂宁宇；

【导师】 颜幼平；

【作者基本信息】 广东工业大学 ， 环境工程， 2004， 硕士

【摘要】 生物法处理低浓度（≤100mg／L）重金属废水时，在投资、运行、操作管理和金属回收、水回用等方面，优于传统的化学法。 本文重点研究了磁场（Fe₃O₄磁粉和固定化永磁粉）对微生物生长的影响，并探讨了磁场作用的机理，另外也对高效吸附菌菌株的筛选、絮凝性能及机理等作了一定的研究。 实验中分别选用Fe₃O₄磁粉和永磁粉作为磁场来源投入培养基中。其中，永磁粉分别以橡胶片固定和海藻酸钠-明胶包埋的方法固定。采用的菌种为课题组前期研究中筛选的两株耐铜细菌菌A和菌B，以及本人自印染废水中筛选得到的两株高效吸附菌2#菌和7#菌。 实验结果表明，耐铜细菌A和B在一定量的Fe₃O₄磁粉产生的磁场作用下生长旺盛，絮凝活性高。Fe₃O₄磁粉投加量为4g／L时，菌A和菌B在稳定期的菌数约为对照组的菌数的2倍，且菌B比对照组提前4个小时进入稳定期。菌A的最大去铜率为73.53％，比对照组最大去铜率高35.76％；菌B最大去铜率为66.91％，比对照组最大去铜率高23.4％。最大去铜率均出现在稳定期后期或衰亡期前期。 对高效吸附菌2#和7#菌的实验研究表明，橡胶片固定的永磁粉对它们的生长均产生了抑制作用；当海藻酸钠-明胶包埋固定的永磁粉投加量为0.065g／L时，高效吸附菌的生长情况和絮凝活性均比对照组好。 实验中还发现磁场对微生物生长的作用（无论是促进还是抑制），只是一种暂时改变其活力、随着磁化时间延长而逐渐趋于稳定的作用。 絮凝活性分布实验表明，菌体及其胞外分泌物均具有较好的吸附作用，因此将菌液直接投入废水中就能达到较好的去铜效果。菌液pH值对吸附效果有很大的影响，将稳定期后期的7#菌（不加磁粉）菌液pH值调到10，用于处理含铜酸洗废水时去铜率可达88.76％。微生物对重金属的吸附符合Langmuir和Freundlich等温吸附模型。更多还原

【Abstract】 The traditional methods for removing heavy metals have several disadvantages when metals are present in concentrations lower than 100 mg/L. Biosorption, which use s biological materials as adsorbents, has been considered as an alternative method.In this work, the effect of magnetic field produced by magnetic powders, such as Fe3O4, fixed permanent magnetic powders were investigated. Moreover, the mechanism of magnetic field and flocculation, and the filtration of bacterium were researched too.Fe3O4 and fixed permanent magnetic powders were chosen as the source of magnetic field and added into the culture medium. The permanent magnetic powders were fixed by rubber and Sodium Alginate-glutin respectively. Strain A and B were provided by the lab, while strain 7# and 2# were filtrated from the printing and dyeing wastewater.The results indicated that the strain A and B propagated well and had high flocculation activity under a certain concentration of Fe3O4. As the Fe3O4 concentration was 4g/L culture medium, the cell numbers of A and B with magnetic field were two times of those without magnetic field in state period. What’s more, cell B with magnetic field came into state period 4 hours ahead of the comparison. The maximum copper removal rate of A was 73.53% and was 35.76% higher than the comparison. While the maximum copper removal rate of B was 66.91% and was 23.4% higher than the comparison. The maximum copper removal rate was both present in anaphase of the state period or prophase of the death period.The permanent magnetic powder fixed by rubber has so strong magnetic intensity that restrained the microorganism’s growth.As the concentration of the permanent magnetic powder embedded by Sodium Alginate-glutin is 0.065g/L, it can improve microorganism’s growth and flocculation activity obviously. The effect of magnetic field on microorganism’s growth, no matter accelerating or restraining, is just temporarily change its activity and will gradually go steady as time goes on.It was demonstrated by the distribution of flocculating activity that both the biomass and the extracellular polymers have a good capacity of removing metals. It was showed that pH value of the biomass influences the flocculation apparently. The maximum copper removal rate of 88.76% was obtained as adjusted the pH value of the biomass to 10. What’s more, the experimental results showed that the adsorption accorded with Langmuir and Freundlich sorption models.更多还原