서지주요정보
광합성 반응기내 Chlorobium thiosulfatophilum 에 의한 hydeogen sulfide 의 산화반응 kinetics = Kinetics of $H_2S$ oxidation by the chlorobium thiosulfatophilum in photosynthetic reactors
서명 / 저자 광합성 반응기내 Chlorobium thiosulfatophilum 에 의한 hydeogen sulfide 의 산화반응 kinetics = Kinetics of $H_2S$ oxidation by the chlorobium thiosulfatophilum in photosynthetic reactors / 김병우.
저자명 김병우 ; Kim, Byung-Woo
발행사항 [대전 : 한국과학기술원, 1991].
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소장정보

등록번호

8001734

소장위치/청구기호

학술문화관(문화관) 보존서고

DCE 9102

SMS전송

도서상태

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초록정보

Biological oxidation of sulfide was studied in order to overcome difficulties in conventional physico-chemical methods for sulfur recovery from toxic gas of hydrogen sulfide. Most investigations employed aerobic bacteria such as Thiobacilli requiring deliberate oxygen control in order to suppress undesirable sulfate production. The inhibition in the aerobic bio-oxidation occurred mostly at the sulfide concentration above 1 mM which resulted in inefficient removal rate of hydrogen sulfide. C. thiosulfatophilum was selected in this study to oxidize sulfide, since its inhibition concentration of substrate sulfide (8 mM) was higher than the inhibition concentration (1mM) for T. denitrificans and it did not require deliberate control of oxygen because of anaerobic physiology. It accepts electron by biological oxidation of hydrogen sulfide to elementary sulfur or sulfate. In the case of electron deficiency the second pathway (equation 2) is favored which is a undesirable side reaction. $2H_2S+CO_2 \stackrel{light}{\longrightarrow} 2S^{\circ}+{CH_2O)+H_2O \qquad\qquad (1)$ $H_2S+2CO_2+2H_2O \stackrel{light}{\longrightarrow} 2(CHO_2O)+H_2SO_4 \qquad\qquad (2)$ Substrate and light inhibitions were investigated in batch reactor to get the basic conditions for the subsequent reactor studies. Inhibition effect of substrate occurred above 6.7 mM of sufide concentration. Light inhibition occurred from about 40,000 lux in sulfide concentration of 5 mM. Light intensity-most important growth parameter, was attenuated due to both the scattering by the elementary sulfur produced and the absorption by the cells. Particle sizes of cell and sulfur were 1.1 ㎛ and 9.4 ㎛. Cells devoted to the turbidity 10 times as sulfur particles of the same concentration. Light attenuation factor was mathematically modelled considering both the absorption and scattering effects based on the Beer-Lambert's law and Rayleigh's theory, which will be applied in the analyses of subsequent reactor studies. Optimum operation conditions relating feed rate vs. light intensity were obtained to avoid pathway 2 and save light energy for 2-and 4-liter fed batch reactors. Appropriate growth kinetics in photosynthetic fed batch reactor was essential to keep up increase of feed rate and light intensity with cell growth. Cell growth kinetics was succesfully approximated by considering the light attenuation factor due to scattering and absorption and the crowding effect of the cells. Light intensity should increase for the same performance rate ($H_2S$ removal rate/unit cell concentration) in enlarged reactor due to the scale-up effect on the light transmission. Immobilization of the cells in alginate beads were carried out to improve the light transmission and the stability and viability of the cells. Calcium ion in Ca-alginate bead made calcium phosphate by chelation effect with phosphate anion in buffer, which resulted in the decrease of light transmission due to white coloured suspension of calcium phosphate as well as leakage-out of cell from alginate matrix. Therefore, alternative choice of strontium-alginate was made, which gave stable maintenance of cross-linking of alginate matrix. Comparing with the free cell reactor, immobilization reactor increased relative activity up to about 40% and decreased the requirement of light intensity about 30%. SEM micrograph and Energy Dispersive X-ray Spectrophotometer were used to analyze the accumulation pattern of elementary sulfur excreted from cells in strontium-alginate bead matrix. Accumulation of sulfur particles improved the strength of bead matrix, but decreased the light transmission into the inner region of immobilized bead. Settling recycle method was applied to remove the sulfur accumulates in the reactor which resulted in light scattering. Sulfur particles in the reactor of about 80% could be recovered by the settler. It resulted in saving of light energy of 50% at the oxidation rate of 1 mmole-$H_2S$/L/hr as well as removal rate increase of 50% comparing with that in the free cell reactor. And metal filter made of stainless steel was used in order to maintain the bacterial activity in near steady state by removing toxic byproducts accumulated in the reactor, supplying fresh medium continuously, and then recycling cells to the reactor. The bacteriochlorophyll-a harvests the light the at 760nm, and transfers the light energy to photosynthetic reaction center P840. Light emitting diode (LED) which emits the light maximum at 710 nm was adopted as an alternative light source to inefficient incandescent light. It emitted light at 760nm about 60% of relative intensity at 710 nm. Light energy of 99% was saved by the application of the LED's array in comparison with the incandescent light source. And the automatic operation of the photo-reactor was done by the control of luminance and volumetric flow rate of mixed gases of $H_2S$, $CO_2$, $H_2$, and $N_2$, so that light intensity and flow rate increased continuously with time according to the optimum operation line supperessing the accumulations of sulfide and sulfate in reactor. The results showed that the accumulations of sulfate and sulfide could be reduced to the concentration below 10% of manual operation.

서지기타정보

서지기타정보
청구기호 {DCE 9102
형태사항 xix, 233 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 수록
저자명의 영문표기 : Byung-Woo Kim
지도교수의 한글표기 : 장호남
지도교수의 영문표기 : Ho-Nam Chang
학위논문 학위논문(박사) - 한국과학기술원 : 화학공학과,
서지주기 참고문헌 : p. 222-230
주제 Oxidation, Physiological
Immobilized cells
광합성 --과학기술용어시소러스
고정화 세포 --과학기술용어시소러스
황화수소 이온 --과학기술용어시소러스
Photosynthesis
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