• 상하수도학회지
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• 제11권4호
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• pp.63-70
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• 1997

The objectives of this study were to find out the optimum treatment conditions for removing nitrogen in a synthetic wastewater by using microorganisms immobilized with PVA-Freezing method. The samples used as influents to the laboratory scale treatment units were a synthetic wastewater. The experiments in this study were mainly directed to collect the data of nitrogen and organic matter removal efficiencies for the different hydraulic and internal recycle rates conditions, temperature and influent C/N ratios. The removal efficiencies of nitrogen and organic matters were investigated for the operating conditions of HRT 2~12hours, internal recycle rates 50~400%, temperatures $15{\sim}30^{\circ}C$ and C/N ratios 2.5~7.5. The adequate internal recycle rate for removing T-N and $BOD_5$ in the synthetic wastewater was found to be about 300% at the temperature of $30^{\circ}C$ when the ratio of carbon contents to the nitrogen (C/N) in the influent was around 5.5. Under these conditions, the final effluent concentrations of T-N and $BOD_5$ were 8.7 and 8.4 mg/l, respectively.

• Membrane and Water Treatment
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• 제4권4호
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• pp.251-263
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• 2013

The internal reflux effect on dialysis through the retentate phase of a countercurrently cross-flow rectangular module is investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycling is analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if cross-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.

• 한국환경과학회지
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• 제8권1호
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• pp.107-113
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• 1999

A new biological nutrient removal system combining $A^2/O$ process with fixed film was developed in this work and the characteristics of denitrification were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of $NO_x-N$, COD, DO and nitrite effects on $NO_x-N$ removal in the CFFR by decreasing hydraulic retention time (HRT) from 10.0 to 3.5 hours and by increasing internal recycle ratio form 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40% / 130% / 25% based on its reactor volume, respectively. It was found that COD rarely limited dentrification in the anoxic reactor because of high $C/NO_x/-N$ ratio in the anoxic reactor, while DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent inhibited denitrification in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent were 0.15mg/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent exceeded the critical points of 0.15mg/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent can assure effective denitrification.

• 멤브레인
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• 제15권2호
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• pp.114-120
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• 2005

본 연구의 목적은 도시 하수처리를 위한 막결합형 $A_2O$공정에 관해 실제적인 정보를 얻고자 하는 것이다. 공경 $0.25\;{\mu}m$의 평판형 정밀여과막을 공기가 주입되는 호기조에 침지시켜 처리수는 저압으로 여과된다. 인공폐수를 대상으로 최적의 처리수질과 장기운전의 안정성 확보를 위한 내부반송율과 MLSS 농도 등의 최적 운전인자를 산정하고자 하였다. 내부반송은 각각 호기조에서 무산조로 반송한 것을 type 1, 무산조에서 혐기조로 반송한 것을 type 2라고 규정지었다. 플럭스는 15 LMH, type 1을 2Q로 고정하고 실험하였을 때 최적의 운전 조건은 MLSS 농도는 11,000 mg/L, type 2가 IQ로 나타났다. 이때, BOD $COD_{cr}$, T-N, T-P의 제거율이 각각 $97.3\%,\;94.2\%,\;64.0\%,\;63.0\%$로 타 내부반송율보다 효과적이었다.

• Korean Membrane Journal
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• 제3권1호
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• pp.32-38
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• 2001

Using the hollow fiber membrane module in a lab-scale membrane bioreactor, the anoxic- oxic (AO) process for nitrogen removal was operated for about one year. For the influent wastewater containing 1,200-1,400 mg $1^{-1}$ of CODcr and 200-310 mg $1^{-1}$ of nitrogen, this process achieved a high quality effluent of less than 30 mgCOD $liter^{-1}$ and 50 mgN $liter^{-1}$. The removal rate of organics was above 98% at a loading rate larger than 2.5 kgCOD $m^{-3}$$d^{-1}$. When the internal recycle from the oxic to the anoxic reactor changed room 2n to 600% rout the influent flow rate, the nitrogen removal rate increased from about 70 to 90% at a loading rate of 0.4 kgT-N m-s d-1. The initial increase of transmembrane pressure (TMP) was observed after a 4-month operation while maintaining the flux and MLSS concentration at 7-9 1 $m^2$ $h^{-1}$ and 6,000-14,000 mg $1^{-1}$, respectively. The TMP could be maintained below 15 cmHg for an 8-month operation. The chemical cleaning with an acid followed by an immersion in an alkali solution gave better cleaning result with the membrane operated for 10 month rather than that only by an alkali immersion.

• 대한환경공학회지
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• 제30권12호
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• pp.1231-1238
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• 2008

본 연구에서는 실험실 규모 2상 혐기성 소화를 이용하여 음식물 쓰레기 탈리액의 처리성을 평가하였다. 이를 위해 산발효조의 적정 유입 pH 및 HRT를 도출하고, 산발효조로의 메탄조 유출수 반송 효과, 메탄발효조에서 고형물 내부반송 및 온도의 영향을 파악하였다. 산발효조에서는 유입 pH 6.0, HRT 2일인 조건에서 메탄조 유출수 반송 후 산생성 및 VS 제거효율은 30% 및 40%에서 안정적으로 유지되었다. 유기물 부하 7 g COD/L/d 이하의 조건에서 고형물 내부반송에 의해 중온 및 고온메탄발효조의 유출수 SCOD는 반송 이전보다 낮거나 같은 수준으로 유지되었고 유기물 부하 증가에 따른 비메탄생성량(specific methane production, SMP)의 감소폭이 줄어들었다. 고형물 내부반송 이후 동일한 유기물 부하에서 COD 제거효율과 SMP는 중온메탄발효조가 고온보다 우수하였으며 이는 중온메탄발효조의 MLVSS 농도가 고온보다 높기 때문인 것으로 판단되었다. 따라서 고온산발효-중온메탄발효로 구성된 시스템이 고온산발효-고온메탄발효보다 COD 제거와 메탄발생면에서 우수한 것으로 나타났다.

• 한국환경보건학회지
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• 제29권3호
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• pp.59-64
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• 2003

This study was conducted to investigate anoxic-RBC-anoxic-RBC process and its application to remove biologically organics and nitrogen. BOD and total-nitrogen(T-N) removal efficiencies were decreased as volumetric loading rate increased. But, the removal efficiency changes of T-N were little, as compared to BOD. Increase of internal recycle rate had few affect of BOD and T-N removal rates. Also, influent allocation(to 2nd anoxic reactor) had few affect of BOD removal efficiency rate. However, when the influent allocation rate was 30%, T-N removal efficiency was increased to 84.1 %. BOD/N ratio applied to 2nd anoxic reactor was increased to range of 3.65-4.37 as influent allocation rate increased to range 20∼35%. But, it might also cause adverse effect such as decrease of denitrification rate in excessive influent allocation rate.

• 환경위생공학
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• 제13권1호
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• pp.91-103
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• 1998

Design data for COD and nitrogen removal from wastewater were collected from Pilot's Multi-stage Bio-reactor. Hyraulic conditions and pollutant loadings were varied in order to optimize the biological and operational parameters. Pilot's experimental results summarize as followings. 1. T-N removal efficiency in the organic volumetric loading 0.2 kgCOD/m$^{3}$·d was obtained as maxium of 85% at internal recycle ratio 2.5 and in more ratio than this it was decreased. Organic removal efficiency was about 91% under the overall experimental conditions and not influenced by recycle ratio.. 2. Nitrification reaction was shown as maxium in the SCOD$_{cr}$/NH$^{+}$-N ratio of 6.5 and in more ratio than this it was decreased. Denitrification rate was the maxium as 85% in more than 7.5 of SCOD$_{cr}$/NO$_{x}$-N ratio and in the ratio over this ratio it becomes constant. 3. By utilizing an applied new model of Stover-Kincannon from Monod's kinetic model, concentration of T-N in the effluent according to flow quanity in the influent was estimated as 8.74 and -67.5 respectively. The formula for estimating T-N concentration of effluent was obtained like this: N$_e$=N$_0$(1- $\frac{8.74}{(QN$_0$/A)-67.05}$)

• 한국환경과학회지
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• 제14권8호
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• pp.771-775
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• 2005

The purpose of this research was to investigate applicative possibility of field. Pilot-scale experiments were conducted, at outdoor temperature, HRT l0hour, IR(Internal Recycle) $150\%$ and used $2.8m^3$ Reactor. External carbon source was varied 80 to 120 mg/L. When External carbon source and Alkalinity were injected to the B3 pilot plant, the removal efficiencies of COD and BOD were not decreased. Nitrification rate were 5.95, 5.40, 4.08 $mgNH_4^+-N/gSS/d$ during operation periods and denitrification rate was $3.l2mgNO_3^--N/gSS/d.$ When we surveyed the relationship between loading rate of nitrogen and nitrogen removal quantity, this data was 0.949, B3 process will be possible application process of field.

• Membrane and Water Treatment
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• 제3권2호
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• pp.113-121
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• 2012

Up-flow multi-layer bioreactor (UMBR) is a hybrid system using dual sludge that consists of an up-flow multi-layer bioreactor as anaerobic/anoxic suspended growth microorganisms followed by an aeration tank. The UMBR acts as a primary settling tank, anaerobic/anoxic reactor, thickener which requires low energy due to mixing by up-flow stream. This study focused on using a pilot UMBR plant with capacity of 20-30 $m^3$/day for domestic wastewater in HCMC. HRTs of UMBR and aeration tank were 4.8 h and 7.2 h, respectively. The average MLSS of UMBR ranged from 10,000-13,600 mg/l SS. Internal recycle rate and sludge return were 200-300% and 150-200%, respectively. The results obtained from this study at flow rate of 20 $m^3$/day showed that removal of COD, SS, TKN, N-$NH_4$, T-N, and color were 91%, 87%, 86%, 80%, 91% and 91%, respectively.