还原Cr（VI）的特异功能菌的选育及其解毒铬的初步研究

【作者】 龙腾发；

【导师】 柴立元；

【作者基本信息】 中南大学 ， 环境工程， 2005， 硕士

【摘要】 铬渣是铬盐行业在生产过程中排放的有毒废渣。每年以数十吨的速度在递增,历年堆存量已达600万吨。铬渣中水溶性的六价铬对环境及人类造成的危害成为社会亟待解决的问题。2003年发生的两起铬渣污染严重事故,引起世人的高度重视,铬渣治理势在必行。但是,目前的干法解毒和湿法解毒方法由于处理成本高、吃渣量小、引起二次污染等原因,不能彻底解决铬渣污染问题。 近年来,生物技术以其经济、高效、无二次污染等优点在环保领域中得到广泛应用,成为关注的热点。但国内外处理含铬废水的微生物仅局限于酸性或中性环境,而且处理Cr（Ⅵ）的浓度仅为200mg·L^-1左右,难以工业化应用,尤其是不可能处理诸如铬渣渗滤液之类的碱性含铬废水及铬渣。 针对铬渣的物化状态、综合前人的相关研究成果,率先提出微生物解毒铬渣的新思路。本研究从自然界中分离到一株能在碱性环境中还原高浓度Cr（Ⅵ）的细菌,并对它的培养条件、生理特性、影响细菌还原铬渣滤液中Cr（Ⅵ）的因素以及铬渣细菌解毒的可行性进行了研究。获得了一些创新性成果,主要体现在: ① 分离筛选了一株还原碱性介质中高浓度Cr（Ⅵ）的细菌,经鉴定,该菌属于无色杆菌属,将其命名为Ch-1。适宜于碱性环境（8<pH<11）、好氧、中温（25-35℃）、可利用有机碳、氮作为营养源。 ② 该菌耐盐（NaCl）性能高,可达20g/L;有效还原Cr（Ⅵ）达1.5g/L,对于1570mg/L的碱性铬渣渗滤液,经细菌作用16h后其浓度可降至0.6mg/L。而其耐受Cr（Ⅵ）的能力可达4g/L,还原及耐受Cr（Ⅵ）的能力远超过当前国内外报道的水平,并将生物治理含铬废水范围扩大到碱性环境。 ③ 经细菌处理后产生的沉淀物中,以Cr（OH）₃计,其百分含量达32.8%,对其进行浸出毒性检测,没有发现Cr（Ⅵ）的存在。这说明细菌能够在碱性介质中彻底还原Cr（Ⅵ）,而且在还原过程中形成的沉淀物具有实际回收价值。 ④ 铬渣细菌浸出试验表明微生物解毒铬渣并回收其中金属铬具有可行性,在进一步优化工艺条件的基础上有望对铬渣进行彻底解更多还原

【Abstract】 Chromium slag is a kind of the poisonous solid waste that is generated from chromate industry. Which increased at the speed of several dozen tons every year, and pile the stock was up to 6 million tons over the years. Harmfulness of the Cr(Ⅵ) in the chromium slag to the environment and human beings has become a urgent problem for our society to solve. Two serious pollute accident occurred by chromium slag in 2003 had attended much attention. The necessity of treating chromium slag had become the common knowledge. But, up to now, methods of dry-detoxification and wet-detoxification can still not solve the pollution problem of the chromium slag because of the high cost, low slag using amount and causing secondary pollution.For these years, Biological technology was used more and more in the environmental protection field and was paid wide attention to for its costless, high-effective, free secondly polluted characteristics. But, Microorganisms for treating Cr(Ⅵ)-containing wastewater were limited in acidic and neutral system at home and abroad, by which the concentration of treated was only about 200 mg/L The method, therefore, was difficult to be applied at industrial scale, especially, to alkaline wastewater containing Cr(Ⅵ) from chromium slag and the slag itself..For the physicochemical state of the slag and on the basis of many investigator’s studied, novel idea of bio-detoxification chromium slag was firstly put forward. In this study, anthor isolated a strain with reducing high concentration Cr(Ⅵ) in alkaline solution from nature. And cultrure conditions, physiology characteristic , factors of affecting Cr(Ⅵ) reduction in alkline filter solution of chromium slag by bacteria and feasibility of detoxificating chromium slag by bacteria were studied. The innovated achievement obtained in this research were showed:The strain with reducing high concentration Cr(Ⅵ) in alkaline solution was isolated. Through identified, the strain is belonging to achromobacter sp., and named as Ch-1. which the suitable growth conditions are: pH 8.0-11.0, 25-35℃ and aerobic. The strain can useorganic-carbon and organic-nitrogen as nutrition sourceThe isolate can tolerate high salinity, reach 20g/L. The ability of effectively reducting Cr(VI) was up to 1.5g/L, especially, With being treated for 16 hours treatment by the isolate, the concentration of Cr(VI) in alkline filter solution of chromium slag was reduced from 1570 mg/L to 0.6 mg/L. Furthermore, the strain can also tolerate 4g/L Cr(VI). The ability of reduction and toleration Cr(VI) are beyond of level reported at home and broad, and the area of treating wasterwater containing Cr(VI) was enlarged to alkline condition.There are 32.8% Cr(OH)3 in the sediment produced by bacteria treating wasterwater containing Cr(VI). And Cr(VI) was hardly detected when ieaching-toxification of sediment was studied. The results showed the isolate can completely reduce Cr(VI) in alkline solution, and the sediment in process has great value of resource reclamation.Leaching experiment of chromium slag by strain showed bio-detoxification chromium slag and reclaiming chrome in the slag were feasible. On the basis of optimizing process conditions , we are looking forward to detoxifying completely chromium slag by microorganism. In the end, we can put forward to a feasible , simple, new method with rational economy for treating alkaline wastewater containing chromium and chromium slag.更多还原