• 한국물환경학회지
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• 제21권4호
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• pp.398-402
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• 2005

The enzyme Xeronine was investigated as a microbial activating substance in biological wastewater treatment processes. Xeronine as bio-stimulant was injected in the anaerobic sludge and the activated sludge treating wastewater in order to examine the effect of hidden benefits. Bio-stimulant did not show significant improvement of anaerobic treatablity. In the aerobic system, higher bio-stimulant dose condition resulted in slightly more removal of nitrogen and phosphorus. Floc aggregation and zone settling velocity as solid-liquid separation factors in activated sludge systems was enhanced by bio-stimulant. Effects of bio-stimulants injection on improvement of water quality and microbial activity did not clear in terms of normal operation conditions.

• 상하수도학회지
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• 제8권3호
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• pp.19-25
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• 1994

In this research, characteristics of nitrification and denitrification using the microorganism attached on sponge and plates were examined. The denitrification and nitrification performance were investigated under the anaerobic and aerobic condition for about 2 months. Because the basins of denitrification and nitrification were connected in series, wastewater was flowed from denitrification basin to nitrification one. The 90% of influent flowrate was returned from nitrification basin to denitrification one. Most of organic material was removed in nitrification basin, wherease the only exact amount of organics required in denitrification process was removed in denitrification one. This experiment resulted in that heterotrophic bacteria existing in aerobic basin governed the removal efficiency of organic compounds. In case the influent BOD concentration into nitrification basin was 80mg/l, it did not affect to accumulation of nitrifying bacteria, the balance of heterotrophic bacteria was proved to be an important factor in nitrification/denitrification method such as anaerobic and aerobic cycling type.

• 한국미생물·생명공학회지
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• 제23권3호
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• pp.352-358
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• 1995

In this study, authors investigated the cadmium tolerance, the accumulation of cadmium, and the cellular distribution of accumlated cadmium in lactic acid bacteria under the anaerobic condition. Lactic acid bacteria grew fairly well in modified EG medium containing 10 ppm of cadmium but could hardly grow at 50 ppm of cadmium. Tolerance to cadmium of genus Lactobacillus was greater than that of genus Streptococcus, and Lactobacillus acidophilus showed the higest cadmium tolerance amomg the bacteria tested. The capacity of cadmium accumlation (9.304-12.428 mg/g wet cell) of lactic acid bacteria was higher than that (6.775 mg/g wet cell) of Escherichia coli. Lactobacillus casei of them took up the largest amount of cadmium. The cadmium elimination amount (28.46-29.25%) of lactic acid bacteria from modified EG medium containing cadmium were also higher than that (14.43%) of Escherichia coli. Accumulated cadmium in Lactobacillus acidophilus was distributed by 42.41% at cell wall, 28.97% at cytoplasm, and 28.62% at plasma membrane, respectively.

• 미생물학회지
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• 제16권3호
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• pp.131-139
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• 1978

Mycoplasma pneumoniae was examined for growth characteristics and morphology when cultivated in several media supplemented with a variety of sera and under different atmospheric conditions. different formula of the medium as well as different sources of lot numbers of the serum in the same medium exhibited varying effects on growth rate and adherence. When the organisms were cultivated in SSR-2 medium in a normal atmospheric environment or under a facultative anaerobic condition provided with carbon dioxide, they developed filamentous cells with heavy growth, whereas mainly round-shaped cells were produced under strict anaerobic conditions of hydrogen and carbon dioxide. Both morphologies of the organism were transformed by switching the incubation environments. An inverted phasecontrast microscopy using modified petri dishes was excellent to observe single cells and useful to follow the development of the cells. Growth, turbidity, and pneumoniae colonies developed on a solid medium and produced clear when overlaid with sheep blood agar.

• 미생물학회지
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• 제25권4호
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• pp.297-297
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• 1987

A $C_{1}$ enriched cellulase fraction was separated from culture filtrate of anaerobic Clostridium thermocellum by hydroxyapatite column chromatography. The separated fraction showed strong synergistic action with $C_{x}$ component (endo-$\beta$-1, 4-glucanase) in digestion of crystalline cellulose, similar to the other aerobic cellulolytic microorganisms. Unlike the $C_{x}$ component the $C_{1}$ enriched fraction was rapidly inactivated by oxidation at the atmospheric condition. The enzyme activity was significantly enhanced by the addition of reducing agents, especially $\beta$-mercaptoethanol, which indicates that a $C_{1}$ component has a lot of sulfhydryl groups essential for the enzyme activity. The effect of metal ions on $C_{1}$ activity was also investigated. The $C_{1}$ fraction was found to be thermally stable compare to endo-$\beta$-1,4-glucanase. Optimal temperature and pH were found to be 60.deg.C and 6.0, respectively.

• 한국농공학회논문집
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• 제62권2호
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• pp.17-29
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• 2020

The objective of this study was to find an optimum methane yield condition in anaerobic digestion of sewage sludge with microwave pretreatment. The pretreatment process was carried out using a lab scale industrial microwave unit (2,450 MHz frequency). The digestion efficiency of pretreated sludge was evaluated by biochemical methane potential (BMP) test. Box-Behnken design and Response Surface Analysis (RSA) were applied to determine the optimal combination of sludge mixing ratio (0 to 100%), power (400 to 1600 W), holding time (0 to 10 min) and pretreatment temperature (60 to 100℃). BMP test results showed that Volatile Solid (VS) removal efficiency was up to 48% at a condition of 0% for mixing ratio, 1600 W for power, 5 min for holding time, and 80℃ for pretreatment temperature. Methane production was up to 832.3 mL/g VS_removed at a condition of 50% for mixing ratio, 1000 W for power, 5 min for holding time, and 80℃ for pretreatment temperature. The results of the variance analysis (ANOVA) showed that the p-value of the power and pretreatment temperature among the independent variables were significant (p<0.05), and in particular, the pretreatment temperature significantly affected on the solubilization and methane production. The optimum condition for the maximum methane yield (847 mL/g VS_removed) was consist of 38.4% of mixing ratio, 909.1 W of power, 4.1 min of holding time, and 80℃ of temperature within the design boundaries.

• 치위생과학회지
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• 제1권1호
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• pp.7-11
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• 2001

Streptococcus mutans는 인간에게 치아우식증을 유발하는 주요 세균으로 구강내에서 치태(plaque)가 형성되고, 탄수화물을 분해하면서 발생되는 유기산에 의해서 생존에 위협을 받게 된다. 하지만 약산성 조건에 노출되어도 산을 경험한 S. mutans는 강산성의 조건에서도 생존할 수 있는 산 저항 및 적응능을 획득하게 된다. 이러한 산 저항능은 Salmonell enterica serovar Typhimurium, E. coli 그리고 Shigella flexneri 등에서 확인 되었던 acid tolerance response(ATR)과 유사한 기작에 의해서 얻어진 것을 알 수 있었다. 이 현상은 산성조건을 경험할 때 유도되는 protein이 주요한 역할을 하는 것을 chloramphenicol 처리에 의해서 알 수 있었다. 동시에 acid shock에 의해서 유도되는 protein 이외에 여러 가지 요소들이 복합적으로 이런 생존 능력을 갖게 하였을 것이라는 가정을 할 수 있게 되었다. 이 연구에 의해서 S. mutans의 혐기적 조건에서의 산 적응기작을 확인하였으며, 산 저항성에 관여하는 유전자의 돌연변이체를 이용한 실험이 추가적으로 필요하다. S. mutans가 구강 내에 생존하는데 필수적인 산 저항기작이 결국 치아우식증 유발의 병독소로 중요한 역할을 하기 때문에 치아우식증의 근본적인 해결을 위한 연구의 일환으로 반드시 시행되어야 할 것으로 생각된다.

• 한국물환경학회지
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• 제21권6호
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• pp.687-694
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• 2005

Lab-scale experiments have been carried out to investigate the effect of F/R ratio of ASBR (Anaerobic Sequencing Batch Reactor) process on the removal of the organic matters in ammonia stripped swine wastewater. Three ASBR inoculated with sludge mixed with granular sludge of UASB (Upflow Anaerobic Sludge Blanket) and anaerobic digested sludge of municipal wastewater treatment plant were operated. Ammonia stripped swine wastewater was used as influent. Prior to conducting the experiments with varied conditions, the effect of increasing organic loading rate from 2.34 to $5.79gTCOD_{Cr}/L$-day at a fixed F/R ratio of 0.1 on the organic removal efficiency has been studied during start-up period. As the result of the experiment, under the condition of varied organic loadings, less than $4.14gTCOD_{Cr}/L$-day, the removed efficiency $TCOD_{Cr}$ of the ASBR process is 83% resulted from the mean value of effluent $TCOD_{Cr}$, 9,125 mg/L during the start-up period. Then ASBRs were operated with F/R ratio of 0.024, 0.303 and 0.91 respectively. Organic loading rate was increased from 4.56 to $15.43gTCOD_{Cr}/L$-day to investigate the effects of F/R ratio and organic loading rate on the organic removal efficiency. As the result of the experiment, less than $6.23gTCOD_{Cr}/L$/L-day, F/R ratio haven't an effect on the organic removal efficiency and the mean removal efficiency of TSS, $TCOD_{Cr}$ and $SCOD_{Cr}$ was about 80%, 86% and 78% at the all of F/R ratio. But as organic loading rate was increased from 8.54 to $12.04gTCOD_{Cr}/L$-day at the F/R ratio of 0.024, the removal efficiency of $SCOD_{Cr}$ decreased from 71% to 63%. The range of decreased removal efficiency of $SCOD_{Cr}$ at the F/R ratio of 0.024 was much more higher than at the F/R ratio of 0.303, 0.91. Thus, as organic loading rate was increased, ASBRs were operated with high F/R ratio to obtain high removal efficiency.

• 대한환경공학회지
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• 제22권4호
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• pp.629-637
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• 2000

고형물 함유 유기폐수의 효율적인 메탄에너지 회수를 위해서 이상소화 반응시스템에 정밀여과시스템을 결합하여 시험하였다. 본 실험에 사용된 막분리 시스템은 산발효조내에 침지시켜 압축공기로 주기적으로 역세척하였고 셀룰로오스재질의 $0.5{\mu}m$ 크기의 막공경을 가진 카트릿지 형태의 정밀여과막을 사용하였다. 메탄발효조는 플라스틱 충진물을 반응기부피의 반 정도 채운 AUBF (Anaerobic Upflow Sludge Bed Filter) 를 사용하였다. 합성폐수는 선분 5,000 mg/L을 기질로 사용하였으며 운전부하에 따른 COD 제거특성을 조사하였다. 산발효조의 HRT는 10일에서 4.5일까지 단계적으로 감소시켰고 이때의 유기물 용적부하는 0.5에서 $1.0kg\;COD/m^3-day$ 로 변회되었다. 한편, 메탄발효조의 HRT는 2.8일에서 0.5일까지 단계적으로 감소시켰고 이때의 유기물 용적부하는 0.8에서 $5.8kg\;COD/m^3-day$까지 변화되었다. 산발효조의 경우 체류시간 4~5 일에서 80% 이상의 우수한 산선환율을 나타내었다. 메탄발효조의 경우에는 장기간의 운전을 통한 슬러지의 입상화에 기인하여 유기물 부하의 변동에 크게 관련없이 95% 이상 (처리수 COD 300 mg/L 이하)의 우수한 COD 제거특성을 나타내었다. 막분리형 이상소화공정은 산발효조의 미생물농도를 증가시켜 산전환율을 향상시킬 수 있는 가능성을 보여 주었고, 복합형 염기성 반응기는 우수한 COD 및 SS 제거를 나타내었다.

• 한국토양비료학회지
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• 제22권4호
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• pp.323-328
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• 1989

절대(絶對) 혐기조건(嫌氣條件)에서 볏짚의 분해작용(分解作用)에 관여(關與)하는 혐기미생물(嫌氣微生物)과 그 분해생성물(分解生成物)들의 행동(行動)을 구명코져 시험(試驗)한 결과(結果)는 다음과 같다. 1. 전(全) 시험기간(試驗期間)동안 처리(處理)에 관계없이 메탄생성균수(生成菌數)가 섬유소분해균수(分解菌數)보다 많았다. 2. 혐기미생물(嫌氣微生物)의 활성(活性)은 볏짚+요소구(尿素區)에서 항온초기(恒溫初期)에 높았던 반면 볏짚단용구(單用區)는 초기(初期)에 감소(減少)되었다가 항온 10日 이후부터 다시 증가(增加)되었다. 3. 중간분해산물(中間分解産物)인 휘발성지방산(揮發性脂肪酸)은 볏짚+요소구(尿素區)보다 볏짚단용구(單用區)에서 그 생성양(生成量)이 높았고 체재기간(滯在期間)도 더 길었으며 이들중 propionic acid함양(含量)이 가장 높았다. 4. 최종분해산물(最終分解産物)인 가스의 발생양(發生量)은 메탄생성균(生成菌)의 활성(活性)과 대단히 밀접(密接)한 관련을 갖고 있었다. 5. 항온기간(恒溫期間)중 액(液)중의 평균 Eh값은 -250mV이었고 이때 $CH_4$:$CO_2$의 %비(比)는 약 60~65 : 35~40이었다. 6. $CH_4$와 $CO_2$ 가스로부터 환산(換算)한 유기물(有機物)의 분해률(分解率)은 볏짚+요소구(尿素區)가 50일(日)동안 45.6%이었으며 볏짚단용구(單用區)는 36.8%이었다.