• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1001-1009
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• 2000

This study is to find the utilization of intermittent aeration system, around S-COD, T-COD, SS, timewise changes of treatment performance, sludge conversion yield, changes of temperature and pH, etc. In consequence of this study, factors of temperature correction showed 1.052 on continuous aeration, and 1.056 on intermittent aeration which is more sensitive to temperature through a minute degree. Meanwhile, sludge conversion yield on intermittent aeration showed lower and more economical than that on continuous aeration. In case of changing pH, treatment water of both reactors worsened slightly in acid but improved in alkali. In general. considering the quality of effluent water, variation pH of effluent water, etc. the case of intermittent aeration was more favorable than that of continuous aeration.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.117-121
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• 2003

SBR과 SBBR 모두 대부분의 유기물은 포기기간에 소모되었으며, SBBR의 경우 부족한 유기물 조건에서도 원활한 탈질화 반응이 일어난 것을 볼 때, 유기물 농도가 낮은 우리나라의 하수에 적합한 공정으로 생각된다. 질산화 속도에 있어서는 유기물과 용존산소의 접촉기회에 있어 유리한 조건을 가진 SBR이 더 크게 나타났다. 그러나 탈질화 반응에 있어서는 SBBR이 더 높은 것으로 나타났다. SBR의 경우 높은 $NO_3$의 존재로 인해 1차 비포기 기간중 인의 방출은 거의 발생하지 않았으나, SBBR의 경우 1차 비포기 기간에 인 방출과 1차 포기기간에 인 섭취가 일어났다.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.08a
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• pp.36-37
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• 2001

큰가리비는 자웅이체이다. 난환형성과정은 난모세포의 발달정도에 다라 다르게 나타나고 있다. 난자형성과정은 난원세포기, 전난황형성난모세포기, 초기난황형성난모세포기, 후기난황형성난모세포기, 성숙난모세포기의 연속적인 5단계의 과정으로 나눌 수 있었다. 전난황형성기 난모세포질 내에서는 핵주변 구역에 골지장치와 수많은 공포들 및 미토콘드리아들이 출현하고 있는데 이들은 차후, 지방적 형성에 관여한다. 난황형성전기난모세포(previtellogenic oocyte)에서는 지방적 및 지질과립들이 핵막 근처에서 출현하여 피질층쪽으로 분산되는 반면, 같은 발달 단계의 난모세포질의 피질구역에서는 피질과립들(단백질성 난황과립)이 처음으로 생성되어 난황막 근처의 피질층에서 핵주변 구역쪽으로 분산.분포된다. 난황형성후기 난모세포에서는 세포질 내의 골지장치, 공포, 미토콘드리아, 그리고 조면소포체들이 자율합성에 의해 난황과립 형성에 관여하고 있다. 반면 외인성 물질들인 지질형태의 과립들, 다량의 글리코겐 입자들이 생식상피 내에서 출현하고 있는데. 이들 물질이 생식상피에서 난황막 구조물인 미세융모를 통해 난황형성 후기 난모세포의 날질 내로 통과해 들어가는 현상이 관찰되었다. 이와같은 현상은 난황형성이 일어날 때에 heterosynthesis가 일어나고 있음을 시사한다. 완숙난모세포의 난경은 약 50~60$\mu\textrm{m}$이다. 정자형성과정은 정원세포기, 제1차정모세포기, 제2차정모세포기, 정세포기, 정자기의 연속적인 5단계로 나눌수 있었다. 정셍포기에서 정자로 변태되는 과정 중에 침체의 분화과정이 있는데 이에는 1. Golgi phase, 2. Cap phase 3. acrosome phase, 4. maturation phase의 단계를 거쳐 첨체가 완성된다. 정자는 원시적 형태를 이루고 있으며 4개의 미토콘드리아가 부핵을 형성하고 있다. 완숙정자 두부의 길이는 대략 $3 \mu$m 이며, 미부의 길이는 약 $30 \mu$m정도이다. 정자 미부편모의 axoneme은 중앙의 2개의 미세소관(microtubule)과 주변에 위치한 9개의 2중 미세소구관(microtublue)으로 이루어져 있다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.17-24
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• 2005

This study was carried out to investigate the removal efficiency of an intermittently aerated nonwoven fabric filter bioreactor fed continuously with domestic sewage. The hydraulic retention time(HRT) of the reactor was reduced from 12 hrs to 10 hrs to 8 hrs during an experimental period of 17 months. In order to search an optimum aeration/nonaeration time ratio for the nitrogen removal at each HRT, the cycle times of 3, 2 and 1 hr were tested at the aeration/nonaeration time ratio of 1. Then, the aeration/nonaeration time ratio was changed from 50 min/70 min to 40 min/80 min to 30 min/90 min at the cycle time of 2 hr which showed the best nitrogen removal. During the experimental period, the effluent SS concentration was always below 1.2 mg/L with more than 95% of BOD removal efficiency. The highest nitrogen removal of 90.1% was observed at the aeration/nonaeration time ratio of 40 min/80 min at the HRT of 10 hr. Oxidation-reduction potential could represent the degree of the nitrification and denitrification reaction in the reactor.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.11-18
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• 2018

As the sequencing batch reactor process is a time-oriented system, it has advantages of the flexibility in operation for the biological nutrient removal. Because the sequencing batch reactor is operated in a batch system, respiration rate is more sensitive and obvious than in a continuous system. The variation of respiration rate in the process well represented the characteristics of biological reactions, especially nitrification. The respiration rate dropped rapidly and greatly with the completion of nitrification, and the maximum respiration rate of nitrification showed the activity of nitrifiers. This study suggested a strategy to control the aeration of the sequencing batch reactor based on respirometry. Aeration time of the optimal aerobic period required for nitrification was daily adjusted according to the dynamics of respiration rate. The aeration time was mainly correlated with influent nitrogen loadings. The anoxic period was extended through aeration control facilitating a longer endogenous denitrification reaction time. By respirometric aeration control in the sequencing batch reactor, energy saving and process performance improvement could be achieved.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.481-489
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• 2019

As aeration is an energy-intensive process, its control has become more important to save energy and to meet strict effluent limits. In this study, predictive aeration control based on the respirometric method has been applied to the sequencing batch reactor (SBR) process. The variation of the respiration rate by nitrification was great and obvious, so it could be a very useful parameter for the predictive aeration control. The maximum respiration rate due to nitrification was about 60 mg O₂/L·h and the maximum specific nitrification rate was about 7.5 mg N/g MLVSS·h. The aeration time of the following cycle of the SBR was daily adjusted in proportion to that which was previously determined based on the sudden decrease of respiration rate at the end of nitrification in the respirometer. The aeration time required for nitrification could be effectively predicted and it was closely related to influent nitrogen loadings. By the predictive aeration control the aerobic period of the SBR has been optimized, and energy saving and enhanced nitrogen removal could be obtained.

• Membrane Journal
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• v.14 no.4
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• pp.289-297
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• 2004

In this study, membranes were coupled to a sequencing batch reactor for simultaneous removal of organic matter and nitrogen, and the influences of MLSS (mixed liquor suspended solid) concentration and the sludge loading rate on membrane fouling and bioactivity were investigated. The amount of membrane fouling slightly increased with MLSS concentration at both non-aeration and aeration conditions, but effect of MLSS concentration was more significant at aeration condition. Although the effect of MLSS concentration on membrane fouling was found to be insignificant at low concentration level, extremely low sludge loading, which were generated by the maintenance of large amount of biomass in the reactor, caused severe membrane fouling, and air scouring effect decreased significantly in this condition. Specific bioactivity was constantly reduced as sludge loading rate decreased. In spite of high MLSS concentration over 17,000 mg/L, the activity of the reactor decreased at extremely low sludge loading rate presumably due to the lower oxygen transfer and the competition of biomass to deficient substrate.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.1
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• pp.31-37
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• 2003

연구목적: 일반적으로 IVF-ET에서 가장 높은 임신율을 얻는 방법은 5 day ET (배반포기 배아 이식)이지만 장기간 배양이 적절하지 못한 경우에는 $2{\sim}4$일째에 ET를 실시하고 나서 $5{\sim}7$일째에 배반포기에 도달한 배아를 재이식 (SET)하여, SET의 효용성에 대하여 조사하고자 실시하였다. 연구재료 및 방법: 48주기의 환자에서 회수한 난자와 수정란은 10%와 20% hFF가 첨가한 DMEM에서 이식 직전까지 각각 공배양하였다. 채란 2일 (group I, day 2 ET), 5일째 이식 (group II, day 5 ET) 또는 재이식 (group III, SET; 2-5, 2-6, 2-7, 3-5, 4-7일)을 실시하면서 수정률, 할구분할률 및 임신율을 각각 비교하였다. 결과에 대한 통계 분석을 SAS (version 6.2)를 이용한 Duncan's Multiple Range Test를 이용하여 p값이 0.05 보다 작을 때 통계적으로 유의차가 있는 것으로 하였다. 결 과: 수정률은 group II (90.5%)가 다른 군에 비하여 높게 (p<0.05) 나타났다 (group I: 80.6%; group III: 82.9%). 할구분할률은 군간에 차이가 없었다 (수정란 당 $93.3{\sim}99.1%$). 임상적 임신율은 group II와 III (각각 58.3%)가 group I (33.3%) 보다 높게 나타났다. 그러나 처리군이 적어서 통계적인 차이는 없었다. 결 론: 배반포기 배아를 단독 이식하는 것이 임신율을 높일 수 있는 최선의 방법으로 나타났지만, 채란수가 적거나 수정률이 저조한 경우에는 $2{\sim}4$일째에 ET를 실시한 후 여분의 배아를 배반포기까지 배양한 다음 $5{\sim}7$일에 재이식 (SET)하면 blastocyst ET에서 나타날 수 있는 이식 자체의 실패를 방지할 수 있으면서 임신율을 높일 수 있는 이식 기법이 될 것이다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.719-725
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• 2005

Anaerobic fill time and feeding pattern in SBR operation were investigated to find way of minimizing poor nitrogen removal efficiency in BNR process without external carbon addition. The three types of the modified SBR operations that were CO-SBR, IA-SBR, and SF-SBR were tested by lab-scale and pilot-scale SBR processes($2\;m^3/day$). In addition, practical equation for biological nitrogen removal was suggested and the equation considered the effect of ratio of fill volume over whole SBR volume and the ratio of step-feed in SBR. The denitrification efficiency of the SF-SBR was best among the three SBRs and followed by IA-SBR, and CO-SBR. The efficiency was 95%, 61%, and 19%, respectively. Looking at the change of sludge floc density by the length of anaerobic fill time, the density of sludge floc at 1 hour and 2 hours of anaerobic fill time were greater than 3 hours of one. The floc size distributions were $100{\sim}300\;{\mu}m$ and $200{\sim}400\;{\mu}m$ with respect to anaerobic fill time 2 hours and 3 hours, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1141-1145
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• 2005

A contactor coupled sequencing batch reactor composed of pre-anoxic contact zone and intermittently aerated zone was proposed and operated for nitrogen removal. Emphasis was placed on the fact that the contactor can be operated in a rapid reaction mode that results In biological uptake but incomplete metabolism of organic matter. Consequently, 61.2% of the sewage SCOD was adsorbed to activated sludge by 30-minute contact reaction. The specific uptake of organic matter was 22.3 mg SCOD/g MLVSS that enhanced the denitrification efficiency in the following denitrification stage. The removal efficiencies of the organic matter(SCOD) and the total nitrogen(T-N) were 86% and about 60% at the TCOD/TKN ratio as low as 6.0, respectively.