• 대한환경공학회지
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• 제33권8호
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• pp.583-590
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• 2011

공기 폭기법을 통해 암모니아를 제거함에 있어, 반응조의 물리적 인자(폭기 깊이, 공기 방울 크기, 표면적)와 알칼리도가 암모니아의 제거 속도에 미치는 영향을 평가하였다. 30 L/min의 공기를 6~53 cm의 폭기 깊이로 실험한 결과, 폭기 깊이는 암모니아 제거 속도에 영향을 미치지 않았다. pH가 10.0, 온도가 $30^{\circ}C$에서 암모니아의 제거 속도 상수와 표준편차는 각각 $0.175h^{-1}$, 0.004로 나타났다. 공기 방울의 크기 및 공기상과 접촉하는 수표면의 표면적은 제거 속도에 영향을 미치지 않았다. 폐수의 알칼리도는 암모니아 제거 속도에 간접적으로 영향을 미치는 것으로 나타났다. 이는 폭기에 의해 이산화탄소가 수용액에 용존되어 pH를 변화시킬 수 있기 때문인 것으로 예상된다. 매립지와 하수 종말 처리장에서 채취한 실제 폐수를 대상으로 암모니아 제거 속도를 살펴보았다. 하수 원수(pH = 7.1, alkalinity = 75 mg/L)의 경우, pH를 9.3으로 조절하여도 암모니아 제거 속도가 크게 증가하지 않았다. 그러나, 알칼리도가 높은 침출수 원수(pH = 8.0, alkalinity = 6,525 mg/L)는 초기 pH가 낮음에도 불구하고, 공기 폭기에 따른 pH 상승으로 인해 암모니아 제거 속도가 증가하는 경향을 나타냈다. 또한, 침출수 원수의 pH를 9.4로 조절한 경우, 하수 원수와 달리 공기 폭기에 따른 pH 저하가 나타나지 않아 암모니아 제거 속도가 유지 되었다.

• 한국환경보건학회지
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• 제30권1호
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• pp.7-14
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• 2004

The change in filamentous bacteria appearance was observed by adjusting factors such as organic and nurient concentration of feed wastewater and the aeration rate in the reactor. In case that COD:N:P and DO were 100:10:1 and 6.1 m1/1 respectively, the mean SVI was 122 ml/g and the filaments were developed normally in flocs. For the low DO con- dition, however, the SVI averaged 186 ml/g and the appearance of outgrowing filaments were more frequent. When the high organic was supplied into the reactor, the average SVI was 274 ml/g and the distinct filamentous bulking was observed. Meanwhile when COD:N:P was maintained at 100: 1 :0.5, the SVI was as low as 87 ml/g and the appearance of filaments were minimal and the size of flocs was small comparing other experimental conditions. For normal, low aeration and high organic concentration, predominant filaments in the early stage of experiments were commonly Type 021N,S. natans which were usually found in low DO condition. However, Type 041, Type 1851, Type 0961 became predominant as experiments extended. Meanwhile, in low nutrient condition, Type 0675, Type 1851, and Type 0961 were observed. The filamentous bacteria appearance for SVI< 150(ml/g), Type 0041, Type 0961 (usually low organic in feed wastewater) were predominantly observed and SVI > 150(ml/g), S. natans and Type 021N(usually low DO in aeration basin) was predominant.

• ALGAE
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• 제22권3호
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• pp.241-246
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• 2007

Cochtodinium votykrikoides -related red tide is the most notorious tidal bloom, resulting in mass mortality to marineanimals. This study aimed to test the effect of C. polyknkoides on the lethality to Haliotis discus hannai under con-trolled conditions. The oxygen demand of C. polykrikoides increases to reach its peak duhng the night, while the oxy-gen usage by H. discus hannai was continuously decreased with a threshold of 2 mg L U. The addition of C.polykrikoides did not effect the respiration of the H. discus hannai. However, the usage of oxygen by C. polykrikoidesduhng the night may lead to anoxia in the animal. With aeration, the level of dissolved oxygen (D.O.) was between6.06 and 7.28 mg LU; 90% of abalones survived even with a high concentration of C. potykrikoides (9000 cells mL U).Without aeration (3 mg LU of D.O.), however, the H. discus hannai suffocated immediately. Once 20 hours hadelapsed, all of the abalones were dead. The density of the H. discus hannai population contributed to their mortality.Therefore, aeration during the night and maintaining lower abalone densities is the best way to promote the sur-vivorship of H. discus hannai during a C. polykrikoides red tide.

• 한국작물학회지
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• 제47권3호
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• pp.186-188
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• 2002

생물반응기에서 배양 수확한 신초의 발근과 순화조건을 알기 위하여 실험한 결과는 다음과 같다. 배양배지는 MS 기본배지의 농도를 반으로 줄이고 아가 농도를 1.2%로 하는 것이 신초의 발근과 순화에 유리하였다. 여과막이 부착된 배양병에서 신초를 생육시키는 것이 밀폐된 배양병에서 생육시킨 것보다 생육이 양호하고 생존율도 높았다. 배지에 paclobutrazol을 0.3-0.4mg/l로 처리한 경우 신초의 발근과 생육이 양호하였다.

• 상하수도학회지
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• 제31권2호
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• pp.169-175
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• 2017

This study applied microbubbles to reduce membrane fouling in wastewater reuse membrane processes, evaluated and compared the transmembrane pressure with or without the application of microbubbles and the cleaning efficiency with the application of aeration and microbubbles. In addition, this study analyzed foulants removed from the membrane surface. Changes in the transmembrane pressure of membranes with the presence or absence of microbubbles were observed. As a result, transmembrane pressure (TMP) increasing rate decreased twofold when applying microbubbles to realize stable operations. This study compared and evaluated cleaning efficiency applying aeration and microbubbles. As a result, the cleaning efficiency was 5% higher on average when applying microbubbles. In turbidity and total organic carbon (TOC), foulants were discharged when applying microbubbles twice as much as applying aeration. It is thought that particulate foulants precipitated on the membrane surface were more likely to desorb because the adhesion between the membrane surface and particle was weakened by microbubbles. Therefore, it is considered possible to effectively control membrane fouling because of the increase in cleaning efficiency when applying microbubbles to wastewater reuse membrane processes.

• 환경영향평가
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• 제14권5호
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• pp.263-273
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• 2005

In this study, the major emission procedures and emission characteristics were identified at the site of sewage treatment plant which is one of the major sources of ammonia. At the same time the emission factors and emission rates were estimated. In order to calculate the emission flux, we used a Dynamic Flux Chamber(DFC), which is found to be a proper sampling devise for area sources such as sewage treatment plant. It was found that the most stable sampling condition was when the stirrer's speed of DFC was 120RPM, and it would be the best time to take a sample 60 minutes later after setting the chamber. The relatively higher flux was shown in Autumn compared to summer and winter. Annual ammonia emission rates procedures were calculated as $906.32{\mu}g/activity-ton$, $1,114.72{\mu}g/activity-ton$ and $437.53{\mu}g/activity-ton$ each at the primary settling basin, aeration basin and the final settling basin, respectively. The ammonia emission rate the highest at in the aeration basin according to this test. This results was due to that the surface of aeration basin or the final settling basin is relatively wider than the primary settling basin.

• Membrane and Water Treatment
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• 제2권2호
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• pp.105-119
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• 2011

This study presents the tests of an Immersed Membrane BioReactor (IMBR) equipped with a draft tube and focuses on the influence of hydrodynamic conditions on membrane fouling in a pilot-scale using a hollow fiber membrane module of ZW-10 under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by a cylindrical draft-tube. The relationship between cross-flow velocity and aeration strength and the influence of the cross-flow on fouling rate (under various hydrodynamic conditions) were investigated using Multi-Dimension Scaling (MDS) analysis. MDS technique is especially suitable for samples with many variables and has relatively few observations, as the data about Membrane Bio-Reactor (MBR) often is. Observations and variables are analyzed simultaneously. According to the results, a specialized form of MDS, CoPlot enables presentation of the results in a two dimensional space and when plotting variables ratio (output/input) rather than original data the efficient units can be visualized clearly. The results indicate that: (i) aeration plays an important role in IMBR performance; (ii) implementing the MDS approach with reference to the variables ratio is consequently useful to characterize performance changes for data classification.

• 상하수도학회지
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• 제38권1호
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• pp.29-38
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• 2024

Wastewater management is increasingly emphasizing economic and environmental sustainability. Traditional methods in sewage treatment plants have significant implications for the environment and the economy due to power and chemical consumption, and sludge generation. To address these challenges, a study was conducted to develop the Intermittent Cycle Extended Aeration System (ICEAS). This approach was implemented as the primary technique in a full-scale wastewater treatment facility, utilizing key operational factors within the standard Sequencing Batch Reactor (SBR) process. The optimal operational approach, identified in this study, was put into practice at the research facility from January 2020 to December 2022. By implementing management strategies within the biological reactor, it was shown that maintaining and reducing chemical quantities, sludge generation, power consumption, and related costs could yield economic benefits. Moreover, adapting operations to influent characteristics and seasonal conditions allowed for efficient blower operation, reducing unnecessary electricity consumption and ensuring proper dissolved oxygen levels. Despite annual increases in influent flow rate and concentration, this study demonstrated the ability to maintain and reduce sludge production, electricity consumption, and chemical usage. Additionally, systematic responses to emergencies and abnormal situations significantly contributed to economic, technical, and environmental benefits.

• 대한환경공학회지
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• 제27권11호
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• pp.1186-1192
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• 2005

간헐폭기시스템에 혐기성 아키아 주입에 따른 질소제거율 변화와 슬러지 발생량변화 및 박테리아의 상관관계를 관찰하기 위해, 표준활성슬러지 공정과 아키아를 주입한 간헐폭기공정과 주입하지 않은 공정을 비교하며 운전하였다. 회분식 실험결과 혐기성 아키아 배양액을 간헐폭기조에 주입한 경우에 유기오염물질 분해율이 향상되었으며, 질산화와 탈질반응 속도가 증가하였다. 특히 표준활성슬러지 공정이나 일반 간헐폭기 시스템에 비해 슬러지 발생량이 매우 낮게 유지되었는데, 이는 혐기성 아키아가 주입됨에 따른 슬러지 생산량이 감소되었기 때문으로 판단된다. 또한, 폭기조에서 용존산소농도를 조절함으로써 혐기성 아키아와 활성슬러지의 공생관계에 따른 효율향상을 간접적으로 확인할 수 있었고 다음과 같은 결과를 얻었다. 1) 아키아 배양액을 주입한 간헐폭기조에서 비산소소비속도(SOUR)는 $2.9\;mg-O_2/(g-VSS{\cdot}min)$이었으며 비산소소비속도와 질산화 속도는 아키아 배양액을 주입하지 않은 반응조보다 높은 것으로 나타났다. 2) 아키아 배양액을 주입한 간헐폭기조, 주입하지 않은 간헐폭기조와 표준활성슬러지 공정에서의 유기물질($TCOD_{Cr}$)의 제거효율은 각각 93%, 90%와 87%이었다. 3) 각각의 반응조에서 모두 질산화 효율은 높았으나, 탈질속도는 아키아 배양액을 주입한 간헐폭기조에서 비교적 매우 높았다. 아키아 배양액을 주입한 간헐폭기조, 주입하지 않은 간헐폭기조와 표준활성슬러지 공정에서 질소제거효율은 각각 75%, 63%와 33%이었다.

• Mycobiology
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• 제40권3호
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• pp.164-167
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• 2012

The effects of aeration through lid filters on the hyphal growth of Lentinula edodes (oak mushroom) in sawdust cultivation bags were investigated. The aeration treatment levels were traditional 27 mm hole cotton plugs, cotton balls and combinations of seven hole sizes ${\times}$ two hole positions (up and under) in the lids covering plastic bags containing 1.4 kg sawdust medium at 63% moisture that had been autoclaved for one hour and inoculated with sawdust spawn of L. edodes strain 921. Aeration treatment effects were measured based on the $CO_2$ concentration at the 15th wk, as well as the hyphal growth rate and degree of weight loss of bags every 14 days for 15 wk. In bags with traditional cotton plugs, the $CO_2$ concentration was $3.8{\pm}1.3%$, daily mean hyphal growth was $2.3{\pm}0.6mm$ and daily mean weight loss was $0.84{\pm}0.26g$. In the bags with 15 mm diameter holes, the $CO_2$ concentration was $6.0{\pm}1.6%$, daily hyphal growth was $2.8{\pm}0.2mm$ and daily weight loss was $0.86{\pm}0.4g$. The bags with 15 mm holes had a higher $CO_2$ concentration and lower water loss than bags with other hole sizes, but the hyphal growth was not significantly different from that of other bags. The weight loss of bags increased proportionally relative to the lid hole sizes. Taken together, these results indicate that traditional cotton plugs are economically efficient, but 15 mm hole lids are the most efficient at maintaining hyphal growth and controlling water loss while allowing $CO_2$ emissions.