Isolation and identification of nondestructive desulfurization bacterium

A nondestructive desulfurization microorganism has been isolated. The metabolism product analyses show that the strain can be a kind of biocatalyst to oxidize dibenzothiophene (DBT) into 2-hydroxydiphenyl (HBP), therefore the sulfur in DBT is removed selectively. The 16SrRNA information, cell wall analysis, physical, biochemical properties and morphological properties suggest that the isolated strain is Rhodococcus erythropolis. The strain can grow in the basal salts medium (BSM) that DBT concentration is no more than 10 mmol/L, and the optimal DBT concentration for growth is 1 mmol/L, however, the optimal DBT concentration for desulfurization is 0.5 mmol/L. The further research shows that the strain can also desulfur some other or-ganosulfur-containing compounds such as thianaphthene, phenyl sulfide and 4,6-dimethyldiben-zothiophene (4,6-DMDBT).     

脱硫菌在自然界硫循环中的作用与意义

硫是生命必需的大量元素,硫循环失衡会造成生态的破坏。通过对硫循环、脱硫细菌的概念的阐述以及对生物脱硫作用机理的介绍,综合分析了脱硫菌脱除不同硫分的作用方式以及脱硫的不同途径,并初步探讨了其在自然界硫循环中的作用与意义。     

一株红球菌脱硫菌株脱硫特性的研究

从炼油厂污水排放口取得的土样中筛选到一株能降解二苯并噻吩 (DBT)的菌株 ,用GC/MS方法 ,证明其降解DBT走硫专一脱除途径 ,即“4S途径” .该菌株被命名为SDUZAWQ ,用微生物生理生化实验及 16SrDNA序列分析初步鉴定为红球菌属 (Rhodococcussp .) .实验结果表明 ,红球菌SDUZAWQ可有效降解苯并噻吩 (BT)和DBT及其甲基衍生物 .在 2d内 ,BT与DBT可同时完全降解 ,0 .5mmol·L-1的BT在 1d内可降解掉 86% ,降解速度高于DBT的降解 .5 MBT的降解率也高于 4,6 DMDBT和 4 MDBT .4 MDBT较 4,6 DMDBT更难降解 ,在 2d内 ,红球菌SDUZAWQ可降解 62 %的 4,6 DMDBT ,而相同条件下 ,4 MDBT仅能被降解 3 6% .     

Comparison of batchstirred and electrospray reactors for biodesulfurization of dibenzothiophene in crude oil and hydrocarbon feedstocks

Biological removal of organic sulfur from petroleum feedstocks offers an attractive alternative to conventional thermochemical treatment, because of the mild operating conditions afforded by the biocatalyst. In order for biodesulfurization to realize commercial success, reactors must be designed that allow for sufficient liquid-liquid and gas-liquid mass transfer, while simultaneously reducing operating costs. Electro-spray bioreactors were investigated for use as desulfurization reactors because of their reported operational cost savings relative to mechanically agitated reactors. Unlike batch-stirred reactors, which mix the biocatalystcontaining aqueous phase with the organic feedstock by imparting momentum to the entire bulk solution, electro-spray reactors have the potential for tremendous cost savings, creating an emulsion <5 (μm in diameter, at a cost of only 3 W/L. Power law relationships indicate that mechanically stirred reactors would require 100-1000-fold more energy to create such a fine emulsion, but these relationships generally do not account for the effect of endogenously produced surfactant in the system. Here, the rates dibenzothiophene (DBT) oxidation to 2-hydroxybiphenyl (2-HBP) in hexadecane, byRhodococcus sp IGTS8 are compared in the two reactor systems. Desulfurization rates ranged from 1.0 to 5.0 mg 2-HBP/(dry g cells · h), independent of the reactor employed. The batch-stirred reactor was capable of forming a very fine emulsion in the presence of the biocatalyst IGTS8, similar to that formed in the emulsion phase contactor (EP^TM), presumably because the biocatalyst produces its own surfactant. Although EPC did not prove to be advantageous for the IGTS8 desulfurization system, it may prove advantageous for systems that do not produce surface-active bioagents, in addition to being mass-transport limited.     

Sulfur-Selective Desulfurization of Dibenzothiophene and Diesel Oil by Newly Isolated Rhodococcus erythropolis NCC-1

A dibenzothiophene （DBT）-desulfurizing bacteria strain was isolated from oil-contaminated soils and identified as Rhodococcus erythropolis NCC-1. Strain NCC-1 was found to convert DBT to hydroxybiphenyl （2-HBP） via the 4S pathway and also be able to use organic sulfur compounds other than DBT as a sole sulfur source. The strain could desulfurize 4,6-dimethyldibenzothiophene （4,6-DMDBT）, which is one of the most recalcitrant dibenzothiophene derivatives to hydrodesulfurization. When two type of oils, a model oil [n-hexadecane （n-C16） containing DBT] and a hydrodesulfurized diesel oil with various organic sulfur compounds, were treated with Rhodococcus erythropolis NCC-1 cells, the total sulfur content significantly decreased, from 150 to 20 mg/L for n-C16 and from 554 to 274 mg/L for diesel oil. The newly isolated strain NCC-1 is considered to have good potential for application in the biodesulfurization of fossil fuels.     

Selection of adsorbents for <Emphasis Type="Italic">in-situ</Emphasis> coupling technology of adsorptive desulfurization and biodesulfurization

In-situ coupling of adsorptive desulfurization and biodesulfurization is a new desulfurization technology for fossil oil. It has the merits of high-selectivity of biodesulfurization and high-rate of adsorptive desulfurization. It is carried out by assembling nano-adsorbents onto surfaces of microbial cells. In this work, In-situ coupling desulfurization technology of widely used desulfurization adsorbents of γ-Al₂O₃, Na-Y molecular sieves, and active carbon with Pseudomonas delafieldii R-8 were studied. Results show that Na-Y molecular sieves restrain the activity of R-8 cells and active carbon cannot desorb the substrate dibenzothiophene (DBT). Thus, they are not applicable to in-situ coupling desulfurization technology. Gamma-Al₂O₃ can adsorb DBT from oil phase quickly, and then desorb it and transfer it to R-8 cells for biodegradation, thus increasing desulfurization rate. It is also found that nano-sized γ-Al₂O₃ increases desulfurization rate more than regular-sized γ-Al₂O₃. Therefore, nano-γ-Al₂O₃ is regarded as the better adsorbent for this in-situ coupling desulfurization technology. Supported by National Basic Research Program of China (Grant No: 2006CB202507) and National High-tech R&D Program (Grant No: 2006AA02Z209)     

煤的微生物法脱硫研究进展

本文综述了煤的微生物法脱硫研究和技术开发进展, 对脱硫菌种、脱硫机理和典型脱硫过程作了较全面的介绍, 还指出了现存的主要问题。