• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.414-422
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• 2006

Before applying PVA bio-beads to practical biological treatment of nitrate-containing wastewater, their characteristics were examined. PVA bio-beads could steadily produce nitrogen gas from nitrate for 28 batches with 0.04 ml/l/h of the maximum gas production rate; however, the maximum gas production rate dropped remarkably thereafter with apparent deformation of beads. Addition of 2.2% solution containing 1% casamino acid, 1% yeast extract, 0.1% mineral solution, and 0.1% vitamin solution to the culture medium resulted in not only recovery of activity of deactivated beads, but also a higher rate of gas production. Calculation of economic benefit for the use of bio-beads in a long-run operation indicated that reactivation of bio-beads by chemicals had economical advantages over packing new bio-beads in the system. The continuously stirred bioreactor exhibited a satisfactory performance at HRT of 20.0 h. With a 9.5 mg $NO_{3}^{-}N/l/h$ nitrate removal rate, nitrate could completely be removed without nitrite accumulation. The use of PVA bio-beads in nitrate removal appears very promising.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.119-129
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• 2014

This work undertook to prepare nanofibers of cellulose nanofibrils (CNF)/polyvinyl alcohol (PVA) composite by electrospinning, and characterize the electrospun composite nanofibers. Different contents of CNFs isolated from hardwood bleached kraft pulp (HW-BKP) by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation were suspended in aqueous polyvinyl alcohol (PVA) solution, and then electrospun into CNF/PVA composite nanofibers. The morphology and dimension of CNFs were characterized by transmission electron microscopy (TEM), which revealed that CNFs were fibrillated form with the diameter of about $7.07{\pm}0.99$ nm. Morphology of the electrospun nanofiber observed by field-emission scanning electron microscopy (FE-SEM) showed that uniform CNF/PVA composite nanofibers were manufactured at 1~3% CNF contents while many beads were observed at 5% CNF level. Both the viscosity of CNF/PVA solution and diameter of the electrospun nanofiber decreased with an increase in CNF content. The diameter and its distribution of the electrospun nanofibers helped explain the differences observed in their morphology. These results show that the electrospinning method was successful in preparing uniform CNF/PVA nanofibers, indicating a great potential for manufacturing consistent and reliable cellulose-based nanofibrils for scaffolds in future applications.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.378-381
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• 2003

질소, 인 등의 영양소 제거를 위한 고정화 미생물을 이용한 새로운 BNR 시스템 개발을 위해 탈질능력이 뛰어난 균주를 순수분리하고 여러 담체를 사용하여 제조된 활성 bio-bead의 특성을 알아보았다. 4종류의 탈질 능력이 뛰어난 균주를 순수분리 하였고, 12% PVA 담체로 만든 bead가 가장 좋은 탈질능력을 보였다. Cell loading 농도는 200 mg/ml일 때 bead의 활성이 최적을 나타내었으며, bead의 size에 의한 탈질효율에는 유의적 차이가 없었다. 제조된 bead는 약 4 batch실험 후 최대 탈질율을 나타내었으며, 약 25번의 batch실험까지는 탈질능력을 그대로 유지하고 cell leaking 양도 약 $10^3$ CFU/ml 정도 였으나, 그 이후로는 bead 형태도 변하면서 cell leaking이 증가하고 탈질능력도 감소되었다.