铀尾矿堆中优势细菌的分离鉴定及其对铀矿浸出的影响
发布时间：2019-05-11 11:46
【摘要】：微生物浸矿作为一种新型的、节约成本的、环境友好的浸矿技术,已经在各种浸矿工艺中得到广泛应用。但是,影响生物浸矿的因素复杂多样,其中工艺因素的合理调控与菌种的耐受性便是急需解决的难题。因此,筛选与培育对铀等低放射性核素有较强耐受能力及浸出能力的微生物,对研究生物浸铀的基础理论有很强的指导作用。本试验从中国广东省韶关市某露天铀尾矿堆中筛选分离出耐铀优势细菌,利用形态观察和16S r DNA基因序列比对方法对该优势细菌进行菌种鉴定,对其进行生长曲线测定并讨论不同的生存因子对其生长的影响,然后探讨了不同影响因素下该优势细菌的耐铀能力及铀浸出能力,并利用SEM和FTIR技术对细菌耐铀性进行机理分析。菌种鉴定结果显示,该优势细菌为苏云金杆菌,简称Bt。初步认为,0~5 h为停滞期,5~27 h为对数期,27~43 h为稳定期,然后过渡到衰亡期。对细菌生长因子的研究试验发现,接种量为4%时该细菌在p H=4.0~10.0、温度为15℃~40℃和Na Cl浓度小于60 g/L的溶液中均能生长。耐受性试验中发现,接种量、p H值、铀离子的初始浓度等都会影响细菌的耐铀能力,细菌接种量越大铀耐受性越强,最优p H值为6.0~8.0,当接种量为25%、温度为30℃、初始p H=4.0时,该菌最低抑制铀浓度为150 mg/L。在低浓度铀废水处理中,该细菌表现了较高的去除率,24 h时达到79.49%。探索试验中与硫酸浸出相比,该细菌对铀的浸出有促进作用,10 h时浸出率达77.93%,同比酸浸高出近40%。在细菌浸铀试验中,体系p H值越靠近细菌的最佳生长p H值,铀的浸出率越高,初始p H=7.0时,铀浸出率为70.51%;矿浆浓度对细菌浸铀的影响较大,当矿浆浓度小于7.5%时,铀的浸出率达68.05%,大于7.5%时,最高铀浸出率为24.13%。菌体量对铀浸出有一定的影响,细菌液/培养基的体积比为1:3时效果最佳。SEM扫描结果显示细菌与铀(Ⅵ)作用前后菌体的表面性状发生了明显的变化,反应前细胞表面光滑,反应后则粗糙不平,FTIR进一步证实了氨基、羧基及磷酸基等在反应过程中起重要作用。
[Abstract]:Microbial leaching, as a new, cost-saving and environmentally friendly leaching technology, has been widely used in various leaching processes. However, the factors affecting biological leaching are complex and diverse, among which the reasonable regulation of technological factors and the tolerance of bacteria are urgent problems to be solved. Therefore, the screening and cultivation of microorganisms with strong tolerance and leaching ability to low radionuclides such as U have a strong guiding role in the study of the basic theory of bioleaching of uranium. In this experiment, the dominant bacteria resistant to uranium were screened and isolated from an open pit uranium tailings pile in Shaoguan City, Guangdong Province, China. The dominant bacteria were identified by morphological observation and 16s r DNA gene sequence comparison. The growth curve of the bacteria was measured and the effects of different survival factors on its growth were discussed, and then the uranium resistance and leaching ability of the dominant bacteria under different influencing factors were discussed. The mechanism of uranium resistance of bacteria was analyzed by SEM and FTIR. The results of strain identification showed that the dominant bacteria were Bacillus thuringiensis (Bt. for short). It is preliminarily considered that 0 鈮，
本文编号：2474464
[Abstract]:Microbial leaching, as a new, cost-saving and environmentally friendly leaching technology, has been widely used in various leaching processes. However, the factors affecting biological leaching are complex and diverse, among which the reasonable regulation of technological factors and the tolerance of bacteria are urgent problems to be solved. Therefore, the screening and cultivation of microorganisms with strong tolerance and leaching ability to low radionuclides such as U have a strong guiding role in the study of the basic theory of bioleaching of uranium. In this experiment, the dominant bacteria resistant to uranium were screened and isolated from an open pit uranium tailings pile in Shaoguan City, Guangdong Province, China. The dominant bacteria were identified by morphological observation and 16s r DNA gene sequence comparison. The growth curve of the bacteria was measured and the effects of different survival factors on its growth were discussed, and then the uranium resistance and leaching ability of the dominant bacteria under different influencing factors were discussed. The mechanism of uranium resistance of bacteria was analyzed by SEM and FTIR. The results of strain identification showed that the dominant bacteria were Bacillus thuringiensis (Bt. for short). It is preliminarily considered that 0 鈮，
本文编号：2474464
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