粉煤灰—微生物絮凝剂联合去除含铅废水的研究

发布时间：2018-05-06 13:04

  本文选题：微生物絮凝剂 + 粉煤灰　； 参考：《内蒙古工业大学》2017年硕士论文

【摘要】：随着社会经济的快速发展,重金属污染情况越来越严重,而作为毒性最大的重金属之一的Pb~(2+),主要来源于工业废水中,其可以通过呼吸道、消化道甚至皮肤进入到人体内,且不断蓄积,从而对人体各系统造成伤害。如何选择一种高效且环保的方法成为研究热点。微生物絮凝剂具有可生物降解、无毒、安全、高效、且没有二次污染等特点,但生产成本高等局限性限制了其规模化生产应用。粉煤灰因为其离子交换容量高、比表面积大等特点逐步代替天然沸石应用于废水处理等领域,但粉煤灰的利用效率较低。因此,本研究提出利用粉煤灰与微生物絮凝剂协同作用去除水中重金属Pb~(2+),从而提高水处理效率。首先,分别单独优化粉煤灰及微生物絮凝剂处理Pb~(2+)的最佳条件,同时根据动力学及热力学模型,揭示反应机制。在此基础上,通过采用响应曲面优化法确定粉煤灰与微生物絮凝剂联合后的最优组合。研究的主要内容和结果如下:采用分离纯化技术从内蒙古地区盐碱地中筛选出一株高效絮凝剂产生菌,编号为HG6,16S rDNA鉴定为Oceanobacillus polygoni。研究优化了这种新型的耐盐,嗜碱型微生物絮凝剂MBF-HG6的生产制备。该微生物絮凝剂产生菌的最佳培养基的碳源,氮源,金属离子和初始pH分别为淀粉,尿素,Fe~(2+)和pH 9.0。所得微生物絮凝剂在0℃至60℃的温度范围内显示出良好的热稳定性。纯化的MBF-HG6含有81.53%多糖和9.98%蛋白质。傅里叶变换红外光谱表明,MBF-HG6中含有羧基,羟基和氨基。通过响应曲面优化法发现当投加6.96 m L MBF-HG6,4.77 mL CaCl2(1%,m/v)和19.24 g/L NaCl时其絮凝活性可以达到90.25%。分别考察粉煤灰与微生物絮凝剂MBF-HG6在不同影响因素下对Pb~(2+)的去除效果,以及研究粉煤灰及MBF-HG6去除Pb~(2+)的过程中的吸附行为等温模型、动力学、热力学,并对粉煤灰及MBF-HG6吸附Pb~(2+)的机理进行了初步探讨。再此基础上,采用BBD法研究了粉煤灰与微生物絮凝剂联合去除废水中Pb~(2+)的最佳条件组合,设定响应值为Pb~(2+)的去除率,方差分析显示,模型F值为17.30,P=0.0005,相关系数R=0.9017,拟合模型极显著。在最优条件下:粉煤灰投加量1.46 g/L,MBF-HG6投加量0.888 g/L,CaCl2投加量15.6 mL/L(1%,w/v),测定Pb~(2+)的去除率达到99.75%。与单独使用粉煤灰去除Pb~(2+)及单独使用MBF-HG6去除Pb~(2+)时相比,节省了粉煤灰及MBF-HG6的投加量。通过Zeta电位分析发现,粉煤灰与MBF-HG6对Pb~(2+)的去除过程中存在电中和作用及吸附架桥机理,在粉煤灰中加入MBF-HG6及助凝剂CaCl_2,对于胶体颗粒脱稳后的絮凝和吸附架桥具有巩固作用,能够实现最大限度地去除含铅废水中的重金属。
[Abstract]:With the rapid development of social economy, the pollution of heavy metals becomes more and more serious. As one of the most toxic heavy metals, Pb~(2 mainly comes from industrial wastewater, which can enter human body through respiratory tract, digestive tract and even skin. And continue to accumulate, thus causing harm to the human body system. How to choose an efficient and environmentally friendly method has become a research hotspot. Microbial flocculants are biodegradable, non-toxic, safe, efficient and have no secondary pollution, but the high production cost and other limitations limit its large-scale production applications. Because of its high ion exchange capacity and large specific surface area, fly ash is gradually replaced by natural zeolite in wastewater treatment, but the utilization efficiency of fly ash is low. Therefore, in this study, the synergistic action of fly ash and microbial flocculant was put forward to remove the heavy metal Pb~(2 in water to improve the water treatment efficiency. Firstly, the optimal conditions of treating Pb~(2 with fly ash and microbial flocculant were optimized separately, and the reaction mechanism was revealed according to the kinetic and thermodynamic models. On this basis, the optimal combination of fly ash and microbial flocculant was determined by using response surface optimization method. The main contents and results are as follows: a strain of high efficiency flocculant producing bacteria was isolated from saline and alkali soil in Inner Mongolia by separation and purification technique, and identified as Oceanobacillus polygoni by rDNA. The production and preparation of this new salt-tolerant and alkalophilic microbial flocculant MBF-HG6 were studied and optimized. The carbon source, nitrogen source, metal ion and initial pH of the microbial flocculant producing strain were starch, urea ferritin 2) and pH 9.0, respectively. The obtained microbial flocculant shows good thermal stability in the range of 0 鈩，

本文编号：1852421