气升式反应器中生物脱硫特性研究

生物工程论文编号:SW175  论文字数:12717,页数:26

II
 目  录 
中文摘要 I
英文摘要 II
目录 III
1. 绪论 1
 1.1 燃料油中的硫及其危害 1
 1.2 燃料油脱硫技术 2
    1.2.1 催化加氢脱硫 3
 1.2.2 生物脱硫 3
 1.3 生化反应设计 4
    1.3.1 搅拌式反应器 4
    1.3.2 气升式反应器 5
 1.4 生物脱硫存在的问题 6
 1.5 本论文的研究内容 7
2. 实验部分 8
 2.1 实验材料   8
 2.1.1 仪器与试剂  8
 2.1.2 培养基  8
 2.1.3 实验用生物菌种制备  9
 2.1.4 菌种衰退防止和保藏  9
 2.1.5 气式反应器实验装置  10
 2.2 实验方法 11
     2.2.1 细胞浓度测定  11
     2.2.2 有机杂环化合物及其产物测定  11
 2.3 微生物脱硫性能研究 13
     2.3.1 摇瓶中休止细胞脱硫活力测定  13
     2.3.2 反应器中休止细胞脱硫活力测定  13

III
3. 结果与讨论 14
 3.1 实验结果与讨论 14
   3.1.1 生长细胞的生长特性比较  14
   3.1.2 休止细胞的脱硫特性比较  15
 3.2 反应器生物脱硫过程中工艺因素考察 16
 3.2.1 表观气速对休止细胞脱硫的影响 16
 3.2.2 水相介质的影响 18
 3.2.3 休止细胞浓度的影响 19
 3.2.4 DBT初始浓度的影响 20
4．总结与展望 22
 4.1 实验总结 22
 4.2 实验展望 22
致谢 23
参考文献 24

 摘要：本文通过采用实验室自主分离的脱硫菌株分支杆菌ZD-19，对促进生物脱硫的工业应用进行研究。考察了ZD-19对4甲基二苯并噻吩(4MDBT)的脱硫特性，实验结果表明ZD-19也能专一性的切断4MDBT的C-S键，且由于4MDBT独特的不对称结构，代谢过程中羟基取代位置发生变化，所得产物为两个同分异构体：4甲基2苯基苯酚和2羟基3甲基联苯。研究还证实ZD-19并不能有效降解苯并噻吩(BT)。本部分实验表明ZD-19是一株对DBT及其衍生物有较高去除效率的优势菌种。
 目前BDS研究还局限于摇瓶实验，生物脱硫反应器的设计与研究具有重要意义。本研究在自行设计的气升式反应器中生物降解正十六烷中的DBT，对气升式反应器的基本工艺参数进行优化。在实验所选的条件下，最佳表观速率为11.8cm/s。表观速率达到13.0cm/s时，出现轻微柱塞流现象，液滴直径增大，传质效果开始降低。反应器中ZD-19休止细胞在生长介质（培养基）和非生长介质（磷酸缓冲溶液）中具有几乎相同的脱硫活性；过低的菌液浓度下不仅两相界面小，传质速率低，也使DBT对细胞的毒性作用明显，脱硫效率很差，实验条件下10-40g/L的菌液浓度都具有较好的比脱硫速率；增加DBT初始浓度，脱硫量略有增加，直至高DBT的致毒作用使菌液脱硫活性降低，此时传质速率较高，体系属于反应控制。
 
关键词：生物脱硫，气升式反应器，模拟燃料油，分支杆菌，二苯并噻吩及其烷基取代物

Abstract: Mycobacterium sp. ZD-19 can metabolize dibenzothiophene(DBT) and 4,6dimethyldibenzothiophene(4,6DMDBT) through a sulfur-specific pathway. The biodesulfurization of 4methyldibezothiophene(4MDBT) by ZD-19 was also investigated in this thesis. The results showed that ZD-19 can also desulfurize 4MDBT through a sulfur-specific pathway. The metabolic pathway for biodesulfurization of 4MDBT was studied, and the final product of 4MDBT biodesulfurization was determined by GC-MS, which were identified as two isomers: 4-methyl-2phenylphenol and 2-hydroxy-3-methyl-biphenyl.
 Biodesulfurization of DBT in oil-aqueous system was carried out in the ALR. The optimal gas velocity was 11.8cm/s. Slight plug-flow was formed when the gas velocity achieved 13.0cm/s, and the oil droplet diameter and the interface area decreased consequently, which were the main causes of the decreased desulfurization rate. The biodesulfurization of resting cells of ZD-19 could be proceed in the non-growth media (phosphate buffer) as efficiently as in the growth medium (BSM).  The desulfurization rate increased with the increasing of DBT concentration as well, while high DBT concentration would inhibit the activity with an optimal of 3 mmol·L-1. The results suggested that under high concentration of DBT and optimal gas velocity, the mass transfer rate was much higher compared to DBT conversion rates, when the microbial desulfurization rate was the overall rate-limiting process step.
Keywords：biodesulfurization; airlift reactor; simulated fuel oil; Mycobacterium sp.; dibenzothiophene(DBT) ; alkylated dibenzothiophenes(Cx-DBTs)