• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.419-422
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• 2000

A three-phase fluidized-bed bioreactor including Thiobacillus sp. IW was tested to remove H_2S and $NH_3$ simultaneously. The inlet $H_2S$ was oxidized to $SO_4^{2-}$ by Thiobacillus sp. IW, and the $NH_3$ reacted with the $SO_4^{2-}$ to form $(NH_4)_2SO_4$. The removal efficiency of $H_2S$ was 98.4-99.9% for an inlet concentration of 36-730 ppm and that of $NH_3$ was 60.2-99.2% for an inlet concentration of 45-412 ppm. The removal efficiency of $NH_3$ was reduced when the inlet loading rate of $NH_3$ was increased above 10 mg/l/h. When the bioreactor was operated for 25 days with a lower inlet concentration of $NH_3$ compared with the of $H_2S$, the bioreactor exhibited an excellent performance with a stable pH, dissolved oxygen content, and cell concentration.

• Clean Technology
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• v.12 no.3
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• pp.165-170
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• 2006

When ammonia ($NH_3$) and hydrogen sulfide ($H_2S$) in binary mixture gases were supplied to a biofilter packed with biomedia made of polyurethane, PVA, and worm cast. No odor gases were detected on the outlet of the biofilter when $NH_3$ and $H_2S$ were separately supplied to the biofilter at space velocity(SV) of $50h^{-1}$ until inlet $NH_3$ concentration was increased up to 300 ppmv and inlet $H_2S$ to 428 ppmv. While, inlet $NH_3$ concentration maintained at 50 ppmv, inlet $H_2S$ concentration increased from 1 to 489 ppmv, and the removal efficiency of each gas was investigated. After that, $NH_3$ concentration increased step by step such as 80, 100, 200, 300, 400 and 500 ppmv. $H_2S$ concentration increased gradually when $NH_3$ concentration was set up at each condition. Under each condition, removal efficiency of $NH_3$ and $H_2S$ gas was investigated by analysing the gases sampled from the inlet and outlet of the biofilter. When binary gases were supplied to the biofilter and inlet $NH_3$ concentration was increased from 50 to 300 ppmv, elimination capacity of $NH_3$ increase linearly as inlet loading increased to $11.14g\;N{\cdot}m^{-3}{\cdot}h^{-1}$. However, as inlet $NH_3$ concentration increased over 300 ppmv, both removal efficiency and elimination capacity decreased while inlet loading increased. $H_2S$ removal efficiency was not affected seriously by the simultaneous supply of $NH_3$ when maximum inlet loading of $H_2S$ was under $40.27S{\cdot}m^{-3}{\cdot}h^{-1}$ and maximum inlet loading of $NH_3$ was under $15.25N{\cdot}m^{-3}{\cdot}h^{-1}$.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.710-714
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• 2009

In this study, we analyzed the desulfurization performance of Zn-based dry sorbents according to the reducing power, water vapor content and $H_2S$ inlet concentration of coal gas in a batch-type fluidized-bed reactor. We used three different coal gas composition with different reducing power such as KRW air-blown coal gas, Shell oxygenblown coal gas and IAE coal gas. The experiments were performed by changing the inlet concentration of water vapor and $H_2S$ in a coal gas. Water vapor content was varied from 5% to 30% and $H_2S$ inlet concentration from 0.5% to 2.0%. As both the water vapor content and $H_2S$ inlet concentration increased, desulfurization performance of Zn-based sorbents decreased regardless of the reducing power of the coal gas. The minimum desuflurization performance was, however, above 99.5% for all experimental conditions, which implied that Zn-based dry sorbents could be used to remove $H_2S$ up to 99%.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.649-655
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• 1999

Biofiltration of polluted gas streams contained $H_2S$ was studied. The experiments were performed in a laboratory-scale reactor with a porous ceramic media inoculated with sulfur oxidizing bacterium, TAS which was isolated from activiated sludge. The concentration of $H_2S$ in the inlet gas varied from 109 to 3,841 ppm, at the various space velocities(SV) of 50 $h^{-1}$ to 250 $h^{-1}$. Various tests have been conducted to evaluate the effects of such parameters as pH, concentration of sulfate ion and retention time on the pressure drop and maximum elimination capacity. The removal efficiency of $H_2S$ decreased as the $H_2S$ concentration or gas velocity increased in the inlet gas. Pressure drop was insignificant in this system. The maximum elimination capacity could reach up to 16.35g-S/kg-dry packing material/day.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.52-59
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• 2003

This study was progressed in photocatalysis of VOCs using $UV/TiO_2$ which was a benign process environmentally. The experiments were peformed to know photodegradation characteristics as crystalline structure of $TiO_2$ which had anatase, rutile and P-25 (anatase : rutile = 70 : 30). The main purpose of this study was to identify photocatalytic characteristics as inlet concentration of reactants, $H_2O$, and residence time. The inlet concentration of VOCs was changed 50, 100 and 200 ppmv, and amount of $H_2O$ was changed 0, 500 and $1000{\;}mg/m^3$, respectively. The deep conversion was increased as the inlet concentration decreased, and the amount of $H_2O$ increased. The deep conversion of benzene had the highest value at $1000{\;}mg/m^3${\;}H_2O$ and 50 ppmv of inlet concentration. The reactivity of reactants was decreased in order benzene > toluene > m-xylene. Also, the photocatalytic deep conversion was increased as residence time increased, because the contact time between reactants and catalyst was increased. In this study, intermediates had not found by GC/MSD analysis. Therefore, the reactants were completely converted to $H_2O{\;}and{\;}CO_2$.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.423-426
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• 2002

A novel process for $H_2S$ gas treatment has been introduced, based on the combined action of a chemical absorption step and a biological step involving the biocatalytic activity of the bacterium Thiobacillus ferrooxidans. The aim of this study is the development of a process for $H_2S$ elimination from gas streams based on that chemical/biological method. The immobilized biomass reactor/chemical adsorption system is suitable for application of the removal of $H_2S$. A double stage reactor was used for the experimental work. The removal efficiencies of over 99% were observed in the range of inlet $H_2S$ concentration from 200 to 1,000ppm. The novel process showed the stable elimination efficiencies of over 95% under the retention time range from 20 to 40sec at the 1,000ppm of $H_2S$ inlet concentration.

• Journal of Environmental Science International
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• v.13 no.1
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• pp.47-53
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• 2004

A biofiltration system using activated carbon/polyurethane composite as solid support inoculated with Bacillus sp. was developed for treating a gaseous stream containing high concentrations of H$_2$S. The effects of operating condition such as the influent H$_2$S concentration and the empty bed contact time (EBCT) on the removal efficiency of H$_2$S were investigated. The biofilter showed the stable removal efficiencies of over 99 ％ under the EBCT range from 15 to 60 sec at the 300 ppmv of H$_2$S inlet concentration. When the inlet concentration of H$_2$S was increased, the removal efficiencies decreased, reaching 95 and 74％, at EBCTs of 10 and 7.5 sec, respectively. The maximum elimination capacity in the biofilter packed with activated carbon/polyurethane composite media was 157 g/m$^3$/hr.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.287-292
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• 2001

A packed bed of volcanic rock was used as deodorizing material to remove hydrogen sulfide($H_2$S) from air in a laboratory-scale column, and was inoculated with Thiobacillus sp. as $H_2S$ oxidizer. The effects of volcanic rock particle size distribution on system pressure drop were examined. Various tests have been conducted to evaluate the effect of $H_2S$ inlet concentration and CBCT(Empty Bed Contact Time) on $H_2S$ elimination. The pressure drop for particles of size range from 5.6 to 10 mm was 14 mm$H_2S$/m at a representative gas velocity of 0.25m/s. Biofilter using scoria and Thiobacillus sp. could get the stable removal efficiencies more than 99.9% under $H_2S$ inlet concentrations in the range from 30 to 1,100ppm at a constant gas flow rate of $15.2{\ell}$/min. $H_2S$ removal efficiencies greater than 99% were observed as long as EBCT was longer than 8sec at the 250ppm of $H_2S$ inlet concentration. When EBCT was reduced to 5.5 sec, $H_2S$ removal efficiency decreased by about 12 percent. The maximum $H_2S$ elimination capacity was determined to be 269g-$H_2S/m^3{\cdot}hr$.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.91-97
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• 2002

Removal of malodorous gases from swine manure by a polyurethane biofilter inoculated with heterotrophic and autotrophic bacteria was investigated. Ammonia, hydrogen sulfide and other gases could be efficiently treated at 3~3.6 second of empty bed retention time by the polyurethane biofilter. In the range of SV $200~l,200h^{-1}$ , the average removal efficiency of odor was about 89% when the odor unit of inlet gas was below 4100. Odor elimination capacity of the polyurethane biofilter was$ 1.8$\times$10^{5}$ $~5.0$\times$10^{7}$OUㆍm$^{-3}$ㆍ$h^{-1}$ that were 84~90% of the inlet load. The critical loads of $NH_3$ and $H_2$S, which mean 97% removal with respect to the inlet loads, were 31 and $27 g.m^{-3}$ ㆍ$h^{-1}$ , respectively. The maximum elimination capacities of $NH_3$ and $H_2$S were 56 and $157 gㆍm^{-3}$ ㆍh$^{-1}$ , respectively. Although the removability for$ NH_3$ and $H_2$S was not influenced by $H_2$S$NH_3$ ratio (ppmv/ppmv), the $H_2$S removability was inhibited by high $H_2$S concentration more than 80 ppmv.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.168-177
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• 1998

The effects of the regeneration parameters such as inlet gas temperature, space velocity, oxygen concentration of the exhaust gas, and initial particulate loading on the oxidation of the particulate inside ceramic cordierite filter have been investigated through an engine experiment. As the inlet gas temperature increases, the remarkable filter temperature occurs owing to the rapid combustion rate. Though the higher space velocity affirms the safe regeneration, it also requires much fuel consumption of the burner. For that reason, the space velocity should be compromised considering the fuel economy. The excessive accumulation of the particulate may cause undesirable regeneration temperatures inside filer even under the optimized regeneration condition. The inlet gas temperature should be selected to overcome the variation of the oxygen concentration which is inherent feature of the diesel engine. It is the most important factor in the regeneration control techniques.