• 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.

• 한국환경보건학회지
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• 제26권3호
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• pp.69-75
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• 2000

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage according to the variation of volumetric ratio in the reactor. It also was performed to provide basic data necessary to the development and improvement of the process which is Anaerobic-Anoxic-Oxic(A2O). In the removal of BOD and COD, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process. In most cases, nitrogen and phosphorus removal efficiency of the process using the cilia media was superior to that of the process which didn't use the media. In the removal of T-N and T-P, the best efficiency of the process showed in the condition of using the media, 1Q of internal recycle rate and 1:3:2 of the volumetric ratio in Anaerobic-Anoxic-Oxic process.

• 상하수도학회지
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• 제21권5호
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• pp.589-599
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• 2007

This study was conducted to investigated the removal efficiency of BOD and nutrient for the treatment of low strength municipal wastewater by a biological nutrient removal system. In this experiment, the effect of operating parameter including HRT of 7.0hr, BOD/TN ratios of 2.62~4.08, internal recycle of 50~300%, and return sludge of 50~100%, were studied during winter season. Efficiencies of organic matter and T-P removal and denitrification were not significantly affected by the change of temperature in winter season. However, the specific nitrification rate and nitrification efficiency decreased at low temperature. Besides, denitrification efficiencies increased with increasing BOD/TN ratios. It was also found that the internal recycle and return sludge ratio below 50% is required for the effective denitrification of low strength municipal wastewater. With operating mode 4 of the optimum, the effluent BOD, T-N and T-P concentration were obtained to average 5.8, 14.6, and 0.84 mg/L, respectively. The temperature-activity coefficient (${\theta}$) of specific nitrification rate, specific denitrification rate and specific phosphorus uptake rate were obtained 1.044, 1.017, 1.028, respectively.

• 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.

• 유기물자원화
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• 제18권1호
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• pp.89-97
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• 2010

본 연구에서는 오존을 이용하여 축산폐수를 전처리하고 일반하수와 연계하여 처리하였을 때 처리효율을 실험실 규모의 장치를 이용하여 비교 분석하였으며 결과는 다음과 같다. 축산폐수의 오존산화 결과 대상폐수의 pH를 산성(pH4), 중성(pH7), 알칼리성(pH10)으로 변화시켰을 때 각각 COD제거율은 시간당 17%, 78%, 62% 로 분석되었다. 오존산화에 의해 NBDCOD 중 일부가 미생물이 분해가능한 BDCOD 로 전환되어 SCODcr/TCODcr 비는 26%에서 약 38%로 증가하였다. 따라서, 오존산화에 의한 축산폐수의 전처리는 난분해성 물질을 생물학적 분해 가능한 물질로 일부 전환시키며 후단 생물학적 처리 단계에서의 제거효율을 높일 수 있는 영향을 미치는 것으로 분석되었다. 오존산화처리된 축산폐수와 하수와의 연계유입수를 MLE(Modified Ludzack-Ettinger) 공정으로 처리한 결과, 내부반송 100%일 때 TCODcr 93.8%, T-N 74.3%, T-P 89.7%, SS 97.5%의 처리효율을 나타냈다. 또한 내부반송율을 150%로 증가시켰을 때 처리효율은 각각 94.5%, 54.5%, 70.8%, 98.5% 로 나타났고, 200%로 증가시켰을 때 처리효율은 각각 92.6%, 83.1%, 81.9%, 98.5% 로 나타났다. 연계유입수를 원수로 사용한 경우 특히 질소제거율은 내부반송율 100%, 150%, 200%에서 각각 74.3%, 54.5%, 83.1%로 나타났으며, 모든 경우에 있어 일반하수를 원수로 사용한 경우보다 질소제거율이 우수한 것으로 분석되었다.

• 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.

• 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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• 제23권6호
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• pp.1061-1066
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• 2014

This study has cross checked the change of internal sludge-recycle in Anaerobic-Digestion, and researched about not only the improvement of Bio-gas production from the digested sludge but also the efficient method of sludge minimization. Ultimate object of the study is to reduce the amount of sludge by the improved efficiency of contact with the organic-matter and the microbes in Anaerobic-Digestion. The sludge-recycle fluidized sludge layer and raised the activity of the sludge, the optimal sludge-recycle ratio, VS and COD removal ratio were 1,000%, 28.2% and 27.7%, respectively. Through these results of this study, it may be of use to treat waste sludge by the sludge-recycle ratio in terms of minimization and circulation of resources.

• 한국산업융합학회 논문집
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• 제15권3호
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• pp.83-86
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• 2012

This study have cross checked the change of internal sludge-recycle in Full-scale Anaerobic-Digestion, and researched about not only the improvement of Bio-gas production from the digested sludge but also the efficient method of sludge minimization. Ultimate aim of the study is to reduce the amount of sludge by the improved efficiency of contact with the organic-matter and the microbes in Anaerobic-Digestion. The sludge-recycle fluidized sludge layer and raised the activity of the sludge, The sludge-recycle ratio of optimum was 500%, VS and COD removal ratio respectively appeared with 67.8% and 70.4%. Through these result of this study, it may be positive view to treat waste sludge by the sludge-recycle ratio in terms of minimization and circulation of resources.

• 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.