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장호남,김은영,안영희,Seong Jin Lim 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.6
A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic acidogenesis of food wastes. When nitrate loading rates ranged from 0.50 to 1.01 kg N/m3·d, the PBR exhibited 100~98.8% NO3--N removal efficiencies and nitrite concentrations in the effluent ranged from 0 to 0.6 NO2--N mg/L. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate loading rate less than 1.01 kg N/m3·d, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower 50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40 mg-N/L.
장호남,김문일,Longan Shang,Dai Di Fan,Jin-dal-rae Choi 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.4
High cell density culturing has been conducted for the production of poly(3-hydroxybutyrate) fed-batch cultures of Ralstonia eutropha with phosphate limitation. It was found that a high glucose concentration inhibited the synthesis of P(3HB) in the high cell density culture of R. eutropha. Although a low glucose concentration can trigger the synthesis of P(3HB) in a manner similar to that of phosphate limitation, it also limited both the P(3HB) synthesis and the cell growth, and led to a low P(3HB) productivity because glucose is the sole carbon source in this reaction. An unstructured model was proposed for predicting the cell growth and P(3HB) synthesis in high cell density cultures of R. eutropha, where the phosphate concentration played a key role in the accumulation of P(3HB) and in cell growth. Good agreements were found between the experimental data and model predictions. The results of simulation showed that the final P(3HB) concentration would decrease more than 25% when the glucose was concentration increased to 40 g/L, and indicated that the optimal glucose concentration for P(3HB) production by high cell density cultures of R. eutropha was around 9 g/L.
High Cell Density Ethanol Fermentation in an Upflow Packed-Bed Cell Recycle Bioreactor
장호남,박중곤,Byoung Jin Kim,Jong Won Kang,Chang Moon Jeong,Nag-Jong Kim 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.2
An upflow packed-bed cell recycle bioreactor (IUPCRB) is proposed for obtaining a high cell density. The system is comprised of a stirred tank bioreactor in which cells are retained partially by a packed-bed. A 1.3 cm (ID) × 48 cm long packed-bed was installed inside a 2 L bioreactor (working volume 1 L). Continuous ethanol fermentation was carried out using a 100 g/L glucose solution containing Saccharomyces cerevisiae (ATCC 24858). Cell retention characteristics were investigated by varying the void fraction (VF) of the packed bed by packing it with particles of 0.8~2.0 mm sized stone, cut hollow fiber pieces, ceramic, and activated carbon particles. The best results were obtained using an activated carbon bed with a VF of 30~35%. The IUPCRB yielded a maximum cell density of 87 g/L, an ethanol concentration of 42 g/L, and a productivity of 21 g/L/h when a 0.5 h-1 dilution rate was used. A natural bleeding of cells from the filter bed occurred intermittently. This cell loss consisted of an average of 5% of the cell concentration in the bioreactor when a high cell concentration (approximately 80 g/L) was being maintained.