The microbial desulfurization of coal

Biodesulfurization of Fossil Fuels: Analysis and Prospective

Biodesulfurization (BDS) of fossil fuels is a promising method for treating the high content of sulfur in crude oils and their derivatives in the future, attributed to its environmental-friendly nature and the technical efficient ability to desulfurize the organosulfur compounds recalcitrant on other techniques. It was found that the bioreaction rate depends on the treated fluid, targeting sulfur compounds, and the microorganism applied. Also, many studies investigated the operation conditions, specificity, and biocatalysts modification to develop BDS efficiency. Furthermore, mathematical kinetics models were formulated to represent the process. In this review, the previous studies are analyzed and discussed. This review article is characterized by a clear picture of all BDS's experimental, industrial, procedural, theoretical, and hypothetical points.

Study of Coal Microbiocenosis for Development of Biotechnological Method for its Desulfurization

A presence of microscopic fungi, heterotrophic bacteria, as well as neutrophilic and acidophilic chemolitotrophic bacteria was determined in coal microbiocenosis. The largest and most active towards pyrite sulfur removal is the Acidithiobacillus genus. Heterotrophic bacteria have the biggest potential when it comes to removal of organic sulfur. Preceding treatment of coal with “silicate” bacteria from the Bacillus genus will allow to use coal microbiocenosis for its biodesulfurisation at its full potential.

Bioleaching of pyritic coal wastes: bioprospecting and efficiency of selected consortia

Pyrite-bearing coal wastes are responsible of the formation of acid mine drainage (AMD), and their management to mitigate environmental impacts is a challenge to the coal mine industry in Europe and worldwide. The European CEReS project sought to develop a generic co-processing strategy to reuse and recycle coal wastes, based on removal of AMD generating potential through bioleaching. Chemolitoautotrophic iron- and sulfur-oxidizing microbial consortia were enriched from a Polish coal waste at 30 °C and 48 °C, but not 42 °C. Pyrite leaching yield, determined from bioleaching tests in 2-L stirred bioreactors, was best with the 48 °C endogenous consortium (80%), then the 42 °C exogenous BRGM-KCC consortium (71%), and finally the 30 °C endogenous consortium (50%). 16S rRNA gene-targeted metagenomics from five surface locations on the dump waste revealed a microbial community adapted to the site context, composed of iron- and/or sulfur-oxidizing genera thriving in low pH and metal rich environments and involved in AMD generation. All together, the results confirmed the predisposition of the pyritic coal waste to bioleaching and the potential of endogenous microorganisms for efficient bioleaching at 48 °C. The good leaching yields open the perspective to optimize further and scale-up the bioleaching process.

Intermediates in the Sox sulfur oxidation pathway are bound to a sulfane conjugate of the carrier protein SoxYZ

The Sox pathway found in many sulfur bacteria oxidizes thiosulfate to sulfate. Pathway intermediates are covalently bound to a cysteine residue in the carrier protein SoxYZ. We have used biochemical complementation by SoxYZ-conjugates to probe the identity of the intermediates in the Sox pathway. We find that unconjugated SoxYZ and SoxYZ-S-sulfonate are unlikely to be intermediates during normal turnover in disagreement with current models. By contrast, conjugates with multiple sulfane atoms are readily metabolised by the Sox pathway. The most parsimonious interpretation of these data is that the true carrier species in the Sox pathway is a SoxYZ-S-sulfane adduct.

Efecto de la cisteína en un proceso de biodepiritización de carbones en lecho empacado

<p>Se llevaron a cabo procesos de biodesulfurización de dos carbones colombianos ricos en azufre (“Mina Vieja” y “Vampiro”), en reactores de lecho empacado a nivel de erlenmeyer, utilizando un consorcio de Acidithiobacillus ferrooxidans (ATCC 23270) y Acidithiobacillus thiooxidans (ATCC 15494), evaluando la adición de cisteína a la solución lixiviante. Los ensayos fueron monitoreados por medidas de hierro en solución, pH y potencial redox. Adicionalmente, se hicieron análisis mineralógicos por difracción de rayos X (DRX) antes y después de los experimentos. Los ensayos sin adición de cisteína alcanzaron una oxidación de pirita de 45.3% y 57.9% para “Mina Vieja” y “Vampiro” respectivamente. Cuando se adicionó cisteína, la oxidación aumentó en 14.9% para “Mina Vieja” y 6.4% para “Vampiro”. Por otra parte, todos los ensayos evidenciaron remoción de caolinita, debido a su interacción con el ácido sulfúrico del medio. Con base en los resultados obtenidos, los componentes del carbón influenciaron tanto crecimiento bacteriano como la eficiencia de la cisteína sobre el grado de pirita oxidada.</p>