• KSBB Journal
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• v.14 no.1
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• pp.124-130
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• 1999

To evaluate the technical of microbial coal desulfurization during the storage in coal dumps, microbial pyrite oxidation in a packed column reactor with Thiobacillus ferrooxidans has been investigated. For microbial desulfurization in a packed reactor system, coal particle size over 1.0 mm with uniform size distribution seems to be most suitable as fas as drainage behavior and accessability of pyrite are concerned. When coal samples of 1∼2 and 2∼4 mm particle size were size were used, about 32∼42% of pyritic sulfur was removed within 70 days. The rate of pyritic sulfur oxidation was in the range of 348∼803 mg S/kg coal ·d, and the sulfur removal rates in packed columns were about 15∼25% of those in suspension cultures. Without any circulation of liquid medium, microbial coal desulfurization could be possible by the inoculation of T. ferrooxidans along on the coal dump. It was concluded that a microbial percolation process is one of possible processes for the desulfurization of high sulfur coal during a long-term storage.

• Journal of Microbiology and Biotechnology
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• v.6 no.5
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• pp.299-308
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• 1996

• Microbiology and Biotechnology Letters
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• v.32 no.4
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• pp.328-333
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• 2004

To treat a waste gas containing a high strength H2S, the two-stages microbial desulfurization process that conof a bioreactor immobilized with Acidithiobacillusferrooxidans and a chemical absorption scrubber has was proposed. After 4 times repeat of batch cultures, the immobilized bioreactor has been stabilized and the rate of iron oxidation reached 0.89 kg . $m^{-3}{\cdot}m^{-1}$ at steady state. The two-stages microbial desulfurization prowas able to be operated for a long term over 54 days. The removal efficiencies of H2S were 97-99% at a space velocity of 70 h-I and a inlet concentration of 37,000 ppmv. The maximum elimination capacity of H2S was approximately 3.3 kg S . $m^{-3}{\cdot}m^{-1}$. In the bioractor, the concentrations of the $Fe^{3+}$ and the immobilzed cell were constantly maintained during the desulfurization.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.31-34
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• 1990

Dibenzothiophene, crude oil and bunker C oil were used in the microbial desulfurization experiments using thermophilic and mesophilic strains of Desulfovibrio and Desulfotomaculum. Mesophilic Desulforvibrio desulfuricans M6 showed the degrees of sulfur removal about 42% and 17% from dibenzothiophene and crude oil, respectively. Thermophilic Desulfovibrio thermophilus showed the degrees of sulfur removal about 68% and 33% from dibenzothiophene and bunker C oil. The strains of Desulfotomaculum were much less efficient than strains of Desulfovibrio. The latter have more complex and stronger gydrogen metabolism. These results showed that desulfurization is closely related to the hydrogen metabolism of the sulfate reducing bacteria.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.400-407
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• 2003

In microbial coal desulfurization process (MCDP) by using Acidithiobacillus ferrooxidans, the effect of process variables on pyritic sulfur removal efficiency has been investigated. The inhibitory effect of toxic materials contained in coal matrix on the activity of desulfurizing bacteria have been evaluated in coal extracts, and the results showed that the method was useful to evaluate the applicability of a coal which is to be desulfurization to MCDP. The removal efficiency increased with decreasing particle size and decreases with increasing pulp density, but has no significant influence of particle size and pup densities at high pulp densities over 20 wt%. The mass transfers of gaseous nutrients such as oxygen and carbon dioxide into coal slurry with various pulp densities and coal particle size has been studied in an airlift bioreactor. Mass transfer coefficient was independent of pulp density in coal slurry with fine particle below 175 $\mu\textrm{m}$, but significantly decreased with increasing pulp density over 225 $\mu\textrm{m}$. The coal particles over 575 $\mu\textrm{m}$ were significantly settled to the bottom of bioreactor resulting in poor mixing. Considering mass transfer, pulp density and coal mixing, an optimal size of coal particle for the microbial coal desulfurization process seems to be about 500 $\mu\textrm{m}$.

• Journal of Energy Engineering
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• v.1 no.1
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• pp.135-151
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• 1992

석탄은 중요한 대체 에너지원 중의 하나이다. 그러나 석탄의 이용은 심각한 환경오염문제를 유발한다. 석탄의 연소와 관련된 환경 오염의 주 원인중의 하나는 석탄의 황 함유로부터 기인한다. 석탄의 연소과정에서 발생되는 아황산 가스는 대기오염과 산성비로 인한 토양오염의 주범중의 하나이다. (중략)

• Clean Technology
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• v.2 no.1
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• pp.53-59
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• 1996

For the development of biocatalysts and processes for microbial desulfurization of petroleum, more than 60 microbial strains capable of DBT(Dibenzothiophene) degradation were isolated from oil-polluted soils through 3 months of continuous and enrichment cultures. Among them, A23-3 strain could grow on DBT as the only sulfur source, while hexadecane was not utilized as a carbon source. The rate of desulfurization by A23-3 in a DBT-glucose medium was satisfactory. The addition of yeast extract or trace metal solution accelerated the rate of desulfurization about 4.5~6.5 times. In case of actual diesel oil treatment, the specific rate of DBT degradation was $0.045g-DBT\;per\;g-cell{\cdot}hour$. A number of aromatic compounds heavier than $C_{14}$ in diesel oil were also degraded by A23-3. A23-3 strain was evaluated as a good catalyst for the production of low-sulfur, low-aromatic clean diesel oil.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.540-543
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• 2000

Microbial desulfurization using a biocatalyst which is capable of selectively liberating sulfur from HDS-refractory organic sulfur compounds is an alternative biotechnology to the current technology of hydrodesulfurization. The system used in the experiments is a two phase system consisting of 0.1%(w/v) dibenzothiophene in hexadecane as model oil and a mineral medium for cell growth. Rhodococcus rhodochrous IGTS8, a desulfurization strain, was grown in flask culture at different oil phase ratio with 10% and 30%. Most of the dibenzothiophene was converted to 2-hydroxybiphenyl when the oil ratio was 10%, but wasn't when the oil ratio was 30%. However, the total degraded DBT amounts were similar. In experiments of adjusting pH to improve the efficiency of degradation, the amounts of degraded DBT were increased by 50%. When the modified medium which has two-fold nutrients than those of minimal salt medium was used, the amounts of degraded DBT were increased by 32%. When both of the methods were used, the efficiency was increased by 136%.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.46-52
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• 2007

As flue gas desulfurization (FGD) wastewater contains high concentrations of nitrate and is very low in organic carbon, the feasibility of nitrate removal by autotrophic denitrification using Thiobacillus denitrificans was studied. This autotrophic bacteria oxidizes elemental sulfur to sulfate while reducing nitrate to elemental nitrogen gas, thereby eliminating the need for addition of organic compounds such as methanol. Owing to the unusually high concentrations of dissolved salts $(Ca^{2+},\;Mg^{2+},\;Na^+,\;K^+,\;B^+,\;SO_4^{2-},\;Cl^-,\;F^-,)$ in the FGD wastewater, extensive laboratory-scale and pilot-scale tests were carried out in sulfur-limestone reactors (1) to determine the effect of salinity on autotrophic denitrification, (2) to evaluate the use of limestone for pH control and as source of inorganic carbon for microbial growth, and, (3) to find the optimum environmental and operational conditions for autotrophic denitrification of FGD wastewater. The experimental results demonstrated that (1) autotrophic denitrification is not inhibited up to 1.8 mol total dissolved salt content; (2) inorganic carbon and inorganic phosphorus must be present in sufficiently high concentrations; (3) limestone can supply effective buffering capacity and inorganic carbon; (4) the high calcium concentration may interfere with pH control, phosphorus solubility and limestone dissolution, hence requiring pretreatment of the FGD wastewater; and, 5) under optimum conditions, complete autotrophic denitrification of FGD wastewater was obtained in a sulfur-limestone packed bed reactor with a sulfur:limestone volume ratio of 2:1 for volumetric loading rates up to 400g $NO_{3^-}N/m^3.d$. The interesting interactions between autotrophic denitrification, pH, alkalinity, and the unusually high calcium and boron content of the FGD wastewater are highlighted. The engineering significance of the results is discussed.

• KSBB Journal
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• v.11 no.2
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• pp.238-245
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• 1996

Microbial desulfurization characterlstics of a bituminous coal have been determined by using Thiobacillus ferrooxidans. The effects of process variables (such as coal pulp density, particle size and addition of surfactants) on pyrite removal have been investigated in both shake and airlift-bioreactor culture experiments. In shake experiments, pyrite could be removed over 78% for pulp densifies below 20% (w/v) and removed below 40% for pulp densities over 30% (w/v) in 8 days. Pyrite removal decreased with increasing pulp densities, and it also decreased sharply with increasing particle sizes. In airlift bioreactor experiments, pyrite at 50% (w/v) pulp density could be removed about 50%. Its value is much higher than 15% at the same pulp density in a shake experiment. With addition of surfactants, pyrite removal was enhanced in shake experiments significantly, whereas it was slightly decreased in an airlift bioreactor experiment.