• Journal of Radiation Protection and Research
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• 제48권2호
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• pp.77-83
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• 2023

Background: The purpose of this study is to purify uranium (U[VI])-contaminated soil-flushing effluent using the precipitation-distillation process for clearance. Precipitation and distillation are commonly used techniques for water treatment. We propose using a combination of these methods for the simple and effective removal of U(VI) ions from soil-flushing effluents. In addition, the U concentration (Bq/g) of solid waste generated in the proposed treatment process was analyzed to confirm whether it satisfies the clearance level. Materials and Methods: Uranium-contaminated soil was decontaminated by soil-flushing using 0.5 M sulfuric acid. The soil-flushing effluent was treated with sodium hydroxide powder to precipitate U(VI) ions, and the remaining U(VI) ions were removed by phosphate addition. The effluent from which U(VI) ions were removed was distilled for reuse as a soil-flushing eluent. Results and Discussion: The purification method using the precipitation-distillation process proposed in this study effectively removes U(VI) ions from U-contaminated soil-flushing effluent. In addition, most of the solid waste generated in the purification process satisfied the clearance level. Conclusion: The proposed purification process is considered to have potential as a soil-flushing effluent treatment method to reduce the amount of radioactive waste generated.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1211-1216
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• 2004

A MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) induced chromium resistant strain ($Cr^{r}18$) of unicellular cyanobacterium Anacystis nidulans has been isolated and characterized. The resistant strain could grow (although restricted to $50\%$ of control) in chromium concentration (180${\mu}M$) lethal to the wild-type. Sublethal ($160{\mu}M$) concentration of $Cr^{6+}$ significantly reduced (13-$37.5$) all the photosynthetic pigments of A. nidulans with maximum reduction in phycoerythrin followed by ChI $\alpha$. Pigments of A. nidulans were drastically decreased in lethal concentration of Cr^{6+} with maximum reduction in phycoerythrin ($75\%$) and allophycocyanin ($67.5\%$). Resistant strain $Cr^{r}18$ resisted toxic effects of sublethal and lethal concentrations of $Cr^{6+}$ on photosynthetic pigments as revealed by less decrease in pigments as compared to A. nidulans. Effect of $Cr^{6+}$ stress was also studied on nitrogen assimilation and phosphate uptake. Sublethal concentration of $Cr^{6+}$ drastically reduced ($71.5\%$) nitrate uptake by A. nidulans while a decrease of $29\%$ was observed in strain $Cr^{r}18$. Short (2 day) exposure of A. nidulans and its resistant strain $Cr^{r}18\;to\;Cr^{6+}$ did not affect nitrate reductase and glutamine synthetase (transferase), whereas longer (10 day) exposure to $Cr^{6+}$ lowered activities of both enzymes in A. nidulans but not significantly in the strain $Cr^{r}18$. Ammonium uptake by both strains was not affected by $Cr^{6+}$. Thus, $Cr^{6+}$ affected photosynthetic pigments, nitrogen assimilation, and phosphate uptake of A. nidulans, while strain $Cr^{r}18$ was able to resist toxic effects of the metal. Advantages of using strain $Cr^{r}18$ for bioremediation purposes have been evaluated by studying $Cr^{6+}$ removal from the solution. Resistant strain $Cr^{r}18$ was able to remove $33\%$ more $Cr^{6+}$ than A. nidulans and thus it can prove to be a good candidate for bioremediation of $Cr^{6+}$ from polluted waters.

• Journal of Animal Science and Technology
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• 제51권4호
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• pp.337-342
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• 2009

회분식 반응조를 Mg원 첨가 방법이나 혹은 MAP을 재이용하는 조건이 서로 다른 4가지 상이한 조건하에서 운전하면서 공정으로부터 회수된 magnesium ammonium phosphate (MAP) 혹은 struvite 슬러리의 재이용 수단으로서의 극초단파조사 방법의 이용 가능성을 파악하였다. 또한 극초단파조사 동안의 MAP 용해율과 $NH_4-N$ 소실양상 및 MAP의 물리/화학적 변화를 분석하였다. Mg원을 첨가하지 않은 run A에서의 용해성 인과 암모니아성 질소의 제거율은 각각 33%와 27% 수준이었던 반면 유입수내 용해성 인 기준 동몰비의 Mg원을 첨가한 run B에서는 용해성 인과 암모니아성 질소의 제거율이 각각 87% 와 40% 수준으로 증가하였다. 극초단파를 조사한 MAP을 첨가한 run C의 경우, 비록 Mg원을 첨가한 run B에 비해 $PO_4-P$와 $NH_4-N$ 제거율이 낮았으나, Mg원을 첨가하지 않은 run A에 비해 $PO_4-P$의 제거율이 2배 정도 높아지는 결과를 보였다. Mg 원과 MAP을 각각 1/2씩 첨가한 run D에서의 $PO_4-P$와 $NH_4-N$ 제거효율은 각각 88%와 35% 수준으로 Mg원만을 1몰비로 첨가한 run B와 거의 유사한 효율을 나타내었다. 이러한 결과에 의거 극초단파로 처리한 후 MAP을 재이용하는 방법은 공정에서의 인과 질소의 제거율을 높임은 물론, Mg원 사용량을 감소시키는 이중효과가 있음을 알 수 있었다. MAP을 극초단파로 조사하면서 $NH_4-N$ 농도변화를 관찰한 결과 극초단파조사 초기단계에서는 $NH_4-N$ 농도가 점차 증가하다가 온도가 $45^{\circ}C$ 이상으로 상승함에 따라 용액으로부터 $NH_4-N$가 소실되기 시작하여 감소하였으며 극초단파조사 동안의 $PO_4-P$ 용해율은 초기 MAP 농도에 비례하면서 $0.0091x^{0.6373}$ mg/sec의 상관관계를 갖는 것으로 분석되었다. 또한 주사전자현미경을 이용한 극초단파조사 동안의 MAP 크리스탈 구조변화실험 결과 극초단파 조사시 전자기적 진동력에 의해 단시간내에 MAP 크리스탈 구조가 작은 입방체 과립형태로 부숴지고 극초단파 조사가 지속됨에 따라 점차 용액내로 녹음을 알 수 있었다.

• 한국환경농학회지
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• 제31권2호
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• pp.185-191
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• 2012

본 연구에서는 산업폐수로부터 분리한 3가지 종의 인 제거율을 확인하였다. 3 가지 분리된 균을 동정한 결과 A1균은 Stenotrophomonas maltophilia strain CUPS 3, A2균은 Rhodococcus erythropolis strain Sco-C01, A3균은 Bacillus sp. 3434BRRJ이었다. 3 가지 분리된 균의 인 제거 및 경유분해를 확인한 결과 인 제거율은 Bacillus sp. 3434BRRJ > Stenotrophomonas maltophilia strain CUPS균 > Rhodococcus erythropolis strain Sco-C01균 순으로 높은 것으로 나타났으며 제거율은 약 99%, 50%, 20%로 확인되었다. 따라서 이 후 실험은 인 제거율이 가장 높았던 Bacillus sp. 3434BRRJ를 가지고 실험하였다. Bacillus sp. 3434BRRJ의 인 제거를 확인하기 위하여 온도별(15, 25 그리고 $30^{\circ}C$), 인 농도별(20, 30 그리고 40 mg/L) 그리고 산소조건(호기, 혐기/호기조건) 및 탄소원을 달리하여 실험하였다. 그 결과Bacillus sp. 3434BRRJ는 $30^{\circ}C$에서 인 제거가 가장 좋았으며 20 mg/L의 인은 약 99% 처리하였고 혐기조건을 거치고 탄소원으로 acetate와 glucose를 혼합하여 처리하였을 때 가장 효율이 좋은 것으로 나타났다. 본 연구에서는 Bacillus sp. 3434BRRJ의 인 제거를 확인 하였다. 균의 생장이 높을수록 인의 제거율은 높았으며, 미생물을 이용한 환경오염물질의 제거에 있어서 가장 중요한 것은 미생물의 활성을 높이는 환경조건을 제공하는 것이다.

• The Korean Journal of Physiology
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• 제2권1호
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• pp.59-71
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• 1968

The uptake of phenolsulfonphthalein (PSP) and of paraaminohippuric acid (PAH) by cortical slices of the rabbit kidney was investigated while varying the composition of medium. The overall uptake of these substances displayed typical active transport characteristics and was significantly enhanced in presence of acetate. When the phosphate buffer was used the optimal pH was 7.4 for both substances. However, when the tris-buffer was used the optimal pH was 7.4 for PSP and 8.3 for PAH. Removal of $Na^+$ from the medium resulted in a significant reduction in the uptake. Similar results, though lesser in magnitude, were obtained when either $K^+\;or\;Ca^{++}$ was removed from the medium. However, there was no additive effect when $K^+\;and/or\;Ca^{++}$ were additionally removed from the $Na^+-free$ medium. The presence of ${NH_4}^+$ greatly reduced while $Li^+\;and\;Mg^{++}$ moderately reduced the uptake of both substances. However, choline had no effect. In substrate-leached slices, acetate greatly enhance the uptake of organic acids; but this action was not demonstrable in absence of $Na^+,\;K^+\;or\;Ca^{++}$.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2001년도 정기총회 특별강연 및 춘계학술연구발표회(2)
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• pp.129-132
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• 2001

The purpose of this research was to understand possibility of foodwaste treatment by hybrid anaerobic reactor(HAR). The Possibility of methane utility and applicability of hybrid reactor system using foodwaste as substrate was investigated. The maximum loading rate and optimized operational conditions were determined. Hybrid anaerobic reactor was filled with packing material 50% of its total volume between the tube and the outer surface. The packing material used was randomly packed open-pore synthesis activated ceramic(SAC) media as support media for microbial attachment, growth, and chemical stability protected bacteria from effect of organic acid accumulation. In this research, although foodwaste has high concentrations C $l^{[-10]}$ and S $O_{4}$$^{2-}$ concentration the possibility of foodwaste anaerobic treatment was when foodwaste is treated by anaerobic digestion, this study focused on the possibility using C $H_4$ gas made under the anaerobic treatment as an alternative energy source. Other objective of this research is to study struvite formation and crystal forms in anaerobic digester. HAR is used to investigate phosphate crystallization without the addition of chemicals.

• BMB Reports
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• 제31권6호
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• pp.572-577
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• 1998

A soluble protein from Saccharomyces cerevisiae provides protection against a thiol-containing oxidation system but not against an oxidation system without thiol. This 25-kDa protein acts as a peroxidase but requires the NADPH-dependent thioredoxin system or a thiol-containing intermediate, and was thus named thioredoxin peroxidase. The protective role of thioredoxin peroxidase against ionizing radiation, which generates reactive oxygen species harmful tocellular function, was investigated in wild-type and mutant yeast strains in which the tsa gene encoding thioredoxin peroxidase was disrupted by homologous recombination. Upon exposure to ionizing radiation, there was a distinct difference between these two strains in regard to viability and the level of protein carbonyl content, which is the indicative marker of oxidative damage to protein. Activities of other antioxidant enzymes, such as catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione reductase were increased at 200-600 Gy of irradiation in wild-type cells. However, the activities of antioxidant enzymes were not significantly changed by ionizing radiation in thioredoxin peroxidase-deficient mutant cells. These results suggest that thioredoxin peroxidase acts as an antioxidant enzyme in cellular defense against ionizing radiation through the removal of reactive oxygen species as well as in the protection of antioxidant enzymes.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1958-1965
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• 2008

A denitrifying polyphosphate-accumulating bacterium (YKP-9) was isolated from activated sludge of a 5-stage biological nutrient removal process with step feed system. This organism was a Gram-negative, coccus-shaped, facultative aerobic chemoorganotroph. It had a respiratory type of metabolism with oxygen, nitrate, and nitrite as terminal electron acceptors. The 16S rRNA gene sequence of strain YKP-9 was most similar to the 16S rRNA gene sequence of Paracoccus sp. OL18 (AY312056) (similarity level, 97%). Denitrifying polyphosphate accumulation by strain YKP-9 was examined under anaerobic-anoxic and anaerobic-oxic batch conditions. It was able to use external carbon sources for polyhydroxyalkanoates(PHA) synthesis and to release phosphate under anaerobic condition. It accumulated polyphosphate and grew a little on energy provided by external carbon sources under anoxic condition, but did neither accumulate polyphosphate nor grow in the absence of external carbon sources under anoxic condition. Cells with intracellular PHA cannot accumulate polyphosphate in the absence of external carbon sources under anoxic condition. Under oxic condition, it grew but could not accumulate polyphosphate with external carbon sources. Based on the results from this study, strain YKP-9 is a new-type denitrifying polyphosphate-accumulating bacterium that accumulates polyphosphate only under anoxic condition, with nitrate and nitrite as the electron acceptors in the presence of external carbon sources.

• 한국환경보건학회지
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• 제22권4호
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• pp.49-54
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• 1996

The anaerobic landfill leachate treatment can surmount dilution problem of high concentration landfill leachate, collect methane gas as byproduct, and treat low phosphate concentration leachate because of low nutrient salt requirement. The problems of conventional anaerobic treatment that are requirement of large reactor because of low microbial growth rate(HRT=20-30 days) and low volumetric loading rate(VLR=0.5-2.0 kg $COD/m^3\cdot day$) are able to surmount by introduction of high rate anaerobic treatment. In this study, the upflow blanket filter(UBF) which is high rate anaerobic process was applyed to the landfill leachate treatment. The acceptable volumetric loading rate and HRT were 18.23 kg $SCOD/m^3\cdot day$ and 13 hrs. SCOD removal rate was over 90% at VLR 18.23 kg $SCOD/m^3\cdot day$. The methane gas yield was $0.15 lCH_4/g$ SCOD added(at STP) at VLR 18.23 kg $SCOD/m^3\cdot day$. The solids accumulation yield was 0.40 g VSS/g COD removed.

• 한국균학회지
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• 제23권1호통권72호
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• pp.86-91
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• 1995

Rhizopus oryzae의 카드뮴 적응 및 해독기작과 이에 관련된 세포내 생리 생화학적 변화를 조사하였다. R. oryzae는 카드뮴을 첨가 배양하였을 때 카드뮴 영향하에서는 carbohydrate metabolic pathway에 관련된 효소 활성(MDH, GPI)이 촉진되고 과산화물 제거에 관여하는 효소가 새롭게 유도(CAT2)된 반면, lactate를 이용하는 효소(LDH, ADH)의 활성이 감소된 사실은 중금속 영향하에서 세포의 성장과 에너지 공급을 위해 에너지 수율이 낮은 lactate를 이용하는 경로보다는 에너지 수율이 높은 TCA cycle 경로에 작용하는 효소들과 독성과산화물 제거에 관여하는 효소의 더 많은 derepression이 필요하다는 것을 알 수 있었다.