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탑형 생물반응기 기포탑과 삼상유동층에서의 회분식 Xanthan 생산
서일순,wolf - Dieter Deckwer ( Il Soon Suh ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1
Tower reactors of a bubble column(0.085 ㎥) and a three phase fluidized bed(TPFB, 0.114 ㎥) were used for the batch production of exocellular polysaccharide xanthan with the aerobic bacteria Xanthomonas campestris. Even at high viscosities the fluidized particles of 8.0 ㎜ glass beads disintegrated the air bubbles, which led to about seven times higher gas-liquid mass transfer coefficient in the TPFB compared to that in the bubble column. On the other hand, the TPFB reactor could be operated in a limited range of xanthan concentrations due to the large bed expansion caused by a considerable increase in the effective viscosity of culture broths during a batch fermentation. Taking into account the high oxygen sorption efficiency(㎏-O₂/kWh), the high energy input rate and the operation complexity, the TPFB bioreactor is expected to be appropriate for the continuous production of xanthan which shows constant rheological properties of culture broths at a steady state.
생물화공 , 에너지 / 환경 : 공기리프트 생물막 반응기에서의 폐수 질화
서일순(Il Soon Suh),허충회(Choong Hoi Heo) 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.2
The nitrifying biofilm was formed on the carriers of granular activated carbon with the diameter of 0.613㎜ in the airlift bioreactor of 27.7L to investigate the influences of temperature and dissolved oxygen concentration on the nitrification rate. The biofilm of 0.140㎜ thickness was obtained after the operation of 130 days with the dilution rate higher than the maximum specific growth rate of nitrifying bacteria. As raising alternately air velocity and ammonium loading rate, ammonium oxidation rate increased stepwise up to the maximum value of 5㎏ N/㎥·d at the riser air velocity of 6.34㎝/s and the temperature of 30℃. The ammonium oxidation rate increased with increasing the dissolved oxygen concentrations, while the nitrite oxidation rates were almost independent from the dissolved oxygen concentration during the early stages of the reactor operation. The biofilm formed at the late phase, however, led the nitrite build-up to disappear and exhibited the nitrite oxidation rates which increased with the dissolved oxygen concentration. As raising temperature, the nitrification rate increased appreciably at the low temperatures of 5℃ to 20℃ and then slightly at the high temperatures of 20℃ to 30℃. The oxygen diffusion in the biofilm played a dominant role at high temperatures rather than the nitrification kinetics.
점성 및 점탄성 액체를 이용한 기포탑에서의 기체 체류량에 관한 연구
서일순 ( Il Soon Suh ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.6
The effects of liquid viscosity and viscoelasticity on gas holdups were studied in a bubble column. For the sake of covering a wide range of the liquid properties, the newtonian sucrose, strongly pseudoplastic and weakly viscoelastic xanthan, strongly viscoelastic polyacrylamide(PAA) and moderately viscoelastic xanthan-PAA mixture aqueous solutions were used as the liquid phase. As increasing the liquid viscosity, the gas holdups decreased in the heterogeneous flow regime. On the other hand, the gas holdups in the slug flow regime increased with the effective viscosity. The gas holdups in the strongly viscoelastic solutions of PAA exhibited lower values than those in the weakly viscoelastic xanthan solutions.
생물화공 , 에너지 / 환경 : 유동층 생물막 반응기에서의 폐수 탈질화 모델
서일순(Il Soon Suh) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.3
A reactor model was developed for the wastewater denitrification in the fluidized bed biofilm reactors with sand and activated carbon particles as support media. The biofilm model proposed by Boaventura and Rodrigues was modified based on the reaction scheme of two consecutive zero-order reactions. The reactor model also includes mass transport of nitrate and nitrite through the liquid film around bioparticles. The effects of liquid-phase mixing in the reactors were also taken account for by assuming the plug flow and the perfect mixing. Thin biofilms formed on the sand support media were fully penetrated by both nitrate and nitrite. On the other hand, the partial penetrations of both species were predicted to occur in thick biofilms on the activated carbon support particles. The removal rates of nitrate and nitrite in the case of full penetration were determined by the biomass quantity of the biofilm, while the surface area of bioparticles determined those in the partial penetration. In the case of partial penetration, the effective diffusivity in the biofilm, the liquid-bioparticle mass transfer and the liquid-phase mixing in the reactor play an important role in determining the volumetric removal rate of nitrate and nitrite.
생물화공 , 에너지 / 환경 : 공기리프트 생물막 반응기에서의 폐수 질화 및 유기물 동시산화에 관한 모델링과 수치모사
서일순(Il Soon Suh) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.4
A reactor model was developed for the simultaneous nitrification and organic oxidation of wastewater in airlift reactors with bioparticles. The diffusion and reaction in the biofilm of bioparticles, liquid-solid mass transfer, and gas-liquid oxygen transfer were taken into account together with the consideration of the nitrification and organic oxidation by the biomass suspended in the liquid phase of the reactor. Double Monod-type kinetics was employed for representing the reactions of the nitrification and the organic oxidation. Using the numerical simulation, it was discussed how the nitrification and the organic oxidation of the wastewater were influenced in the airlift reactor by effective diffusivity in the biofilm, bioparticle media size, air velocity and reactor operation pressure, flow rate and organic concentration of the feed, and maximum organic oxidation rate in the biofilm. The oxidation rate of ammonia and nitrite increased at the given conditions of the air velocity, the media amount and the biofilm thickness, as decreasing the media size. It was demonstrated in the simultaneous nitrification and organic oxidation of wastewater that the nitrite oxidation was first affected by the reactor liquid-phase concentration of dissolved oxygen and the organic oxidation was influenced by the biomass suspended in the liquid phase of reactor. As increasing the organic concentration of the feed, the organic oxidation rate increased but the oxidation rates of ammonia and nitrite decreased.