• International Journal of Fluid Machinery and Systems
• /
• 제5권1호
• /
• pp.10-17
• /
• 2012

The objective of this study was to investigate the oxygen transfer characteristics of an ejector aeration system. In order to evaluate the oxygen transfer performance of the ejector aeration system, a comparative experiment was conducted on a conventional blower aeration system. The effect of entrained air flow rate and aerating water temperature on the oxygen transfer efficiency was investigated. The dissolved oxygen concentration increased with increasing entrained air flow rate, but decreased with increasing aerating water temperature for two aeration systems. The volumetric mass transfer coefficient increased with increasing entrained air flow rate and with increasing aerating water temperature for both aeration systems. The average mass transfer coefficient for the ejector aeration system was about 20% and 42% higher than that of the blower aeration system within the experimental range of entrained air flow rates and aerating water temperatures.

• 한국환경보건학회지
• /
• 제13권2호
• /
• pp.83-90
• /
• 1987

The objective of this study is to review the basic theories related substrate removal in wastewater flow variations using submerged biofilm reactor. An aerated biofilm reactor is that in which influent organic substrates are aerobically oxidized by the microorganisms of biofilm grown on the surface of submerged media. No sludge is returned, and oxygen is supplied by diffusers. Three types of aerated biofilm reactor are one stage-central aeration, one stageup flow aeration and two stage-side aeration. The orders of substrate removal capacity in wastewater flow variations showed two stage-side aeration, one stage-upflow aeration and one stage-central aeration. The phenonmenon of nonclosing volid in upflow aeration type was superior to these in central-side aeration type. Attached biofilm masses in case of upflow, side and central aeration reactor were 1.0mg/cm$^2$, 4.1 mg/cm$^2$ and 0.93 mg/cm$^2$, respectively. Yield coefficient for biofilm was 0.31 to 0.48. Especially, removal efficiency can be increased remarkably according to the number of biofilm reactor and the packed condition of media.

• 한국환경과학회지
• /
• 제14권9호
• /
• pp.861-871
• /
• 2005

This study was carried out to get more operational characteristics of Anoxic(anaerobic)-Oxic-Anoxic-Oxic $(AO)_2$ sequencing batch biofilm reactors (SBBRs) at the low TOC concentration, The operating time in anoxic (anaerobic) time to oxic time was I : I. Experiments were conducted to find the effects of the aeration time distribution on the organic matters and nutrients removal. Three lab-scale reactors were fed with synthetic wastewater based on glucose as carbon source. During studies, the operation mode was fixed. The first aeration time to the second aeration time in SBBR-I was 2 : 3, and those in SBBR-2 and SBBR-3 were I : 4 and 3 : 2, respectively. The organic removal efficiency didn't show large difference among three reactors of different aeration time distribution. However, from these study results, the optimum aeration time distribution in the first and the second aeration time for biological nutrient removal was shown as 3 : 2. The release of phosphorus was inhibited at the second non-aeration period because of the low TOC concentration and the nitrate produced by the nitrification at the first aeration period.

• 한국환경농학회지
• /
• 제17권4호
• /
• pp.301-305
• /
• 1998

본 연구는 농가에서 사용하는 저류조, 연속 폭기조, 혐기성 정치식, 혐기성 교반식의 4가지 형태의 부숙조를 이용하여 액상 가축분 퇴비 부숙효율을 평가하기 위하여 수행하였다. 호기성 폭기조는 BOD 및 악취 제거율에서 혐기성 부숙방법보다 우수하였다. 반면에 질소는 초기농도의 47%가 손실되어 혐기성 부숙방법보다 심한 편이었다. 혐기성 부숙방법중 교반식과 정치식간에는 큰 차이는 인정되지 않았다. 그러나 혐기성 교반식이 정치식보다 대장균 제거율, 악취제거율은 더 높았으며, 질소 손실율은 더 낮게 나타났다. 농가에서 사용하는 저류조 형태의 부숙조는 혐기 또는 호기성 처리 방법보다 BOD, 대장균, 악취제거율등이 낮았다. 각 개별요인들의 효율을 종합 평가한 결과 액비 부숙효율은 혐기성 교반조>호기성 폭기조>무교반 혐기성조>저류조 순으로 높았다.

• 상하수도학회지
• /
• 제25권6호
• /
• pp.981-987
• /
• 2011

Biologically treated water contains a large quantity of organic matters and microorganisms which can cause various problems to membrane. The membrane fouling occurred by these reasons is hard to control by single physical cleaning. This study analyzes the efficiency of aeration with chemical backwashing and foulants removal during chemical backwashing. The cleaning efficiency improves when the chemical concentration is high and the contact time of chemical is long. Chemical backwashing with aeration shows exceptional cleaning efficiency which leads the physical cleaning is required during chemical backwashing since it forms flow inside the membrane submerged tank. From the foulants removal analysis, the particles such as turbidity and TOC removal rate increase when the aeration is applied. Dissolved matter of DOC and UV254 removal is dependent on higher chemical concentration. According to FTIR analysis, one of major foulants, the polysaccharide is controlled by the chemical backwashing with aeration condition.

• 디지털융복합연구
• /
• 제10권10호
• /
• pp.221-227
• /
• 2012

한국에서 오염물 해양투기는 하수슬러지 처리방식으로 널리 사용되어 왔다. 하지만 2009년 이후 적용되어 온 음식폐기물과 하수슬러지의 해양투기 오염 방지에 관한 런던 협약에 따라 2013부터 엄격한 법적 제재가 예상된다. 따라서, 고농축 유기 슬러지 처리 를 위한 고효율 포기 시스템을 사용한 현장 실험실 테스트가 하수 및 산업폐수처리장에서 적용이 되었다. 연구 결과는 고효율 포기 시스템이 유기성 슬러지의 감량화에 매우 유용한 것으로 나타났으며, 구체적인 결과는 다음과 같다. 첫째로 고효율 포기 시스템을 이용한 슬러지 소화시 유기물 제거율은 56.2 ~ 85.8 %이었다. 이러한 결과가 일반 하수 처리효율보다 낮지만, 고효율 포기 시스템의 처리대상 슬러지가 공장 폐수임을 고려할 때 매우 유용한 것으로 판단된다. 둘째로 슬러지 평균 제거 효율은 약 25.2 %이었다. 셋째로 고효율 포기 시스템에 의한 슬러지 처리비용에 효과적으로 기여할 수 있는 것으로 드러났다. 특히, 고효율 포기 시스템이 높은 고농도 슬러지를 함유하거나, 산업페기물이거나 고농도의 강열잔류 고형물(FS) 포함되어 있는 경우의 소규모 하수 및 폐수 처리장의 현장 처리에 더욱 효과적이다.

• 한국물환경학회지
• /
• 제22권2호
• /
• pp.358-363
• /
• 2006

KSMBR process is dynamic state advanced wastewater treatment applied with Trisectional Aeration (TSA) mode combined with membrane. TSA was remodeled conventional intermittent aeration which was operated nonaeration-aeration. TSA operates nonaeration ($N_1$) - aeration (A) - nonaeration ($N_2$) in Trisectional Aeration Reactor (TAR). Organics of influent could be nearly consumed to denitrification without influence by remained DO in TAR and it could be operated about sludge return ratio of 1Q (influent base). The purpose of this study was to apply KSMBR to the full-scale plant and to evaluate efficiency of nitrogen and phosphorus removal and TSA operation. The result of this study, average CODcr/T-N and CODcr/T-P ratio were 7.8 and 59.6, respectively. BOD, TCODcr, SS, T-N, T-P, E-coli removal efficiency were 98.4, 95.2, 73.0, 69.6, 99.95 %, respectively. KSMBR obtained high removal efficiencies of C, N and P when it applied full-scale plant.

• ALGAE
• /
• 제39권2호
• /
• pp.109-127
• /
• 2024

High production and efficient harvesting of microalgae containing high omega-3 levels are critical concerns for industrial use. Aeration can elevate production of some microalgae by providing CO₂ and O₂. However, it may lower the production of others by generating shear stress, causing severe cell damage. The mixotrophic dinoflagellate Gymnodinium smaydae is a new, promising microalga for omega-3 fatty acid production owing to its high docosahexaenoic acid content, and determining optimal conditions and methods for high omega-3 fatty acid production and efficient harvest using G. smaydae is crucial for its commercial utilization. Therefore, to determine whether continuous aeration is required, we measured densities of G. smaydae and the dinoflagellate prey Heterocapsa rotundata in a 100-L semi-continuous cultivation system under no aeration and continuous aeration conditions daily for 9 days. Furthermore, to determine the optimal conditions for harvesting through centrifugation, different rotational speeds of the continuous centrifuge and different flow rates of the pump injecting G. smaydae + H. rotundata cells into the centrifuge were tested. Under continuous aeration, G. smaydae production gradually decreased; however, without aeration, the production remained stable. Harvesting efficiency and the dry weights of omega-3 fatty acids of G. smaydae + H. rotundata cells at a rotational speed of 16,000 rpm were significantly higher than those at 2,000-8,000 rpm. However, these parameters did not significantly differ at injection pump flow rates of 1.0-4.0 L min^-1. The results of the present study provide a basis for optimized production and harvest conditions for G. smaydae and other microalgae.

• 한국환경농학회지
• /
• 제32권4호
• /
• pp.366-368
• /
• 2013

BACKGROUND: Composting is the most frequently used waste management process for animal manure in Korea's livestock industry. In the composting process, a large amount of nitrogen (N) is volatilized to the atmosphere as amonia ($NH_3$). However, quantitative information of $NH_3$ emission from composting of liquid manure is required to obtain emission factors for management of livestock manure in Korea. METHODS AND RESULTS: To evaluate the $NH_3$ emission from composting of liquid manure affected by aeration, we conducted composting of liquid pig manure with three forced aeration systems. The aeration conditions were continuous (A60), cycle of 30 min aeration and 30 min pause (A30S30) and without aeration(A0). All treatments were aerated 12 hour per day with these aeration systems. The total ratio of $NH_3$ volatilization loss to total N content in liquid manure throughout composting period was estimated to 19.9% for A0 treatment, 25.9% for A30S30 treatment and 36.3% for A60 treatment. The A30S30 and A60 aeration systems increased $NH_3$ volatilization by 30.2 and 82.3% compared with systems without forced aeration. CONCLUSION(S): Ammonia emission during liquid pig manure composting was highly affected by forced aeration. The development of liquid pig manure composting systems with forced aeration would be considered both reducing ammonia emission and efficiency of composting.

• 한국환경보건학회지
• /
• 제18권2호
• /
• pp.57-61
• /
• 1992

This study was made for enhanced removal of N and P by intermittented aeration Activated Sludge Process. Experiment were conducted to find the effects of aeration interval and nutrient removal efficiency. When applied aeration interval were 30~60 min, 2~4 h, 4~8 h, organic matter was not affected while phosphorous removal was aeration interval 30~60 min. Also, when applied mixing intensity were 15, 30, 45 and 60 rpm, organic matter was not affected while removal was maximum at 15 rpm. Total nitrogen and phosphorous removal were in the range of 76 and 85%. Density and MLSS of Sludge were in the range of 2.3~2.6 and 7198~7810 mg/l. Release of phosphorous from activated sludge under unaerobic condition was increased as pass time.