Biodesulfurization Of High-sulphur Coal By Newly Isolated Bacteria

Sulfur-oxides from combustion of coal have caused a serious environment pollution problem. More and more stringent environment pollute control standards demand deep desulfurization technology. Compared to traditional technologies, biodesulfurization technology has some advantages such as the mild reaction conditions, less equipment and operational costs, and selective removal of sulfur from coal. As a result biodesulfurization technology will be a efficient deep desulfurization technology.A new strain named YBS2# that can degrade dibenzothiophene(DBT) into 2-hydroxybyphenyl (2-HBP)was isolated from the sewage of Hohhot refinery. The strain was identified as Microbacterium based on morphological observations, as well as physiological and biochemical tests. The optimal carbon source(glycerol) and nitrogen source(ammonium chloride) were obtained by single-factor tests and orthogonal test. The results of single-factor tests and orthogonal test also showed that the optimal operational conditions were as follows: initial pH, 7.5, temperature, 30℃, concentration of DBT, 0.1mM, inoculum size(%), 10%, broth content, 200mL broth per 500mL flask. Under the optimal conditions, the degradative ratio of DBT reached 64% in 4 days.A pint-sized desulfurization bioreactor was designed and the desulfurization activity of YBS2# for organic sulfur in high-sulphur coal was studied in the reactor. The strain removed 70.45% of organo-sulfur and 45.05% of total sulfur from crude coal in 7 days. The effect of tempertrue, initial pH, coal granularity, coal slurry concentration, stirring speed and ventilation rate on desulfurization efficiency were observed. The results showed that the optimal conditions were as follows: temperature, 35℃, initial pH, 7.5, coal granularity, 150, coal slurry concentration, 10%, stirring speed, 160r/min, ventilation rate, 2.0L/min.At the same time, a new strain named DDT which can remove sulfurous iron ore from coal was isolated from the colliery in Datong city and identified as Thiobacillus. In the bioreactor, strain DDT removed 58.5% of sulfurous iron ore and 33.5% of total sulfur in 14 days. Studies on the influence of tempertrue, initial pH, coal granularity, coal slurry concentration, stirring speed and ventilation rate on desulfurization efficiency showed the optimal operational conditions were as follows: coal granularity, 150, coal slurry concentration, 10%, stirring speed, 150r/min, ventilation rate, 1.0L/min. The study on desulfurization of organic sulfur and that of sulfurous iron ore from high-sulphur coal by the two strains in the reactor will provide a reference for the application of the biodesulfurization technology in the future.