• 한국환경과학회지
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• 제13권7호
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• pp.675-680
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• 2004

This study was conducted to remove organics and nutrients using 2 stage intermittent aeration reactor. First reactor, using suspended microbial growth in intermittent aeration instead of anaerobic reactor in the typical BNR process, used minimum carbon source to release P, and it was possible to reduce ammonia loading going to second reactor. In the second reactor, using moving media intermittent aeration, it was effective to reduce nitrate in non-aeration time by attached microorganisms having long retention time. In aeration time, nitrification and P uptake were taken place simultaneously. From the experiment, two major results were as follows. First, the removal of organics was more than 90%, and optimum aeration/non-aeration time ratio for organic removal was corresponded with aeration/non-aeration time ratio for nitrogen removal. Second, in the first reactor, optimum aeration/non-aeration time ratio was 15/75 (min.) because it was necessary to maintain 75 min. of non-aeration time to suppress of impediment of return nitrate and to lead release of phosphate. In the second reactor, optimum aeration/non-aeration time ratio was 45/90 (min.).

• 한국환경보건학회지
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• 제32권5호
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• pp.451-461
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• 2006

Laboratory scale experiments were conducted to study the conversion of sludge from conventional activated sludge to nitrogen-phosphorus removal sludge using two types of sequencing batch reactor (SBR) systems, a conventional SBR and sequencing batch biofilm reactor (SBBR). The nitrogen and phosphorus removal characteristics were similar between SBR and SBBR and the removal efficiencies were very low when the influent TOC concentrations were low. The nitrogen and phosphorus removal efficiencies in SBR were 96% and 77.5%, respectively, which were higher than those in SBBR (88% and 42.5%) at the high influent TOC concentration. In SBBR, the simultaneous nitrification-denitrification was occurred because of the biofilm process. The variations of pH, DO concentration and ORP were changed as the variation of influent TOC concentration both in SBR and SBBR and their periodical characteristics were cleary shown at the high influent TOC concentration. Especially, the pH, DO concentration and ORP inflections, were cleary occurred in SBR compared with SBBR.

• 대한환경공학회지
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• 제32권1호
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• pp.97-104
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• 2010

현재 강화된 방류수 수질 기준에 발맞춰 질소 인 제거를 포함한 고도처리 공정을 건설 중이거나 기존 표준활성슬러지 공정에서 고도처리공정으로의 개선이 추진되어지고 있다. 그러나 다양한 고도처리공정의 적용을 검토함에 있어 제거 효율 측면에서의 단순 평가만이 사용되고 있다. 따라서 고도처리공정 적용 시 제거 효율 뿐 아니라 슬러지 생산, 포기 비용 등을 복합적으로 평가할 수 있는 방법이 필요하였다. 따라서 본 연구에서는 표준활성슬러지 공정으로 운영 중인 S 하수처리장을 Biological nutrient removal(BNR) 공정으로 개선할 경우를 가정한 대안 공정 평가 방법을 제안하였다. 시간적, 비용적 장점을 가지며 객관적인 평가 기준으로 대두되고 있는 수학적 모델을 이용한 시뮬레이션을 통해 대안 공정으로 선정된 Anaerobic/anoxic/oxic ($A^2$/O), Virginia initiative plant (VIP), Daewoo nutrient removal (DNR) 공정에 대해 평가하였다. 시뮬레이션 결과를 바탕으로 공정의 처리 성능 뿐 아니라 슬러지 생산량 및 에너지 효율을 포함한 5가지 성능 지수들을 적용함으로써 개별 항목간의 비교 평가가 가능하였으며, 최적 공정을 제시하기 위한 객관적 판단과정을 퍼지 추론을 통하여 구현하였다.

• 한국환경보건학회지
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• 제31권4호
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• pp.340-348
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• 2005

Laboratory scale experiments were conducted to compare the performance of two types of sequencing batch reactor(SBR) systems, anoxic-oxic-anoxic-oxic $((AO)_2)$ SBR and anoxic-oxic-anoxic $(A_2O)$ SBR on the biological nitrogen and phosphorus removal. Also, the profiles of DO and pH in reactors were used to monitor the biological nutrient removal in two SBRs. The break point in the pH and DO curves at the oxic period coincided with the end of nitrifying activity at about 1 h 30 min in oxic phase, and the change in pH appears to be related to nitrate concentration. The TOC removal efficiency in $A_2O$ SBR was higher than that in $(AO)_2$ SBR. The denitrification was completed at the influent period. The 2nd non-aeration and aeration periods were not necessary for the nitrogen and phosphorus removal because of the low influent TOC concentration in this study. The release and uptake of phosphorus in $AO_2$ SBR was much higher than that in $(AO)_2SBR.$ In order to uptake more phosphorus, the 1st aeration period in $A_2O$ SBR should be prolonged.

• 대한환경공학회지
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• 제22권1호
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• pp.121-132
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• 2000

TCODcr 380mg/L이며 TKN이 65mg/L, TP 12mg/L가량인 도시하수의 질소, 인 제거를 위하여 $13{\sim}28^{\circ}C$에서 선단무산소조를 설치한 영양소제거공정(Bio-NET)을 $10m^3/d$ 규모의 pilot plant를 설치하여 내부반송율과 SRT를 변화시켜 운전하여 질소, 인 제거 특성을 살펴 보고 이를 시뮬레이션 프로그램을 이용하여 모사한 결과를 상호 비교하였다. SS, CODcr의 경우 각각 94%, 87%의 제거효율을 안정적으로 보였으며, 질소의 경우 52%~89%로 평균 75%의 제거효율을 보였다. 또한 인의 경우 안정적으로 평균 90% 이상의 높은 제거효율을 보여주었다. 또한 선단무산소조에서는 유입수내에 높은 $COD/NO_3-N$가 유지되어 비탈질속도는 평균 9.04mgN/gMv/hr로 분석되었다. 인의 거동은 유입수의 SCOD부하에 의해 큰 영향을 받는 것으로 나타났으며 비인용출속도는 평균 6.25mgP/gMv/hr를 보였다. 혐기조에서 비인용출속도는 평균 1.0mgP/gMv/hr를 보였고 폭기조에서 비질산화속도는 평균 2.9mgN/gMv/hr로 분석되었다. GPS-X 프로그램을 이용하여 모델의 내부인자 중 종속영양미생물군의 최대비중식속도, 인의 용출에 관련된 Short Chain Fatty Acid(SCFA) limit, 인의 섭취와 관련된 COD 이용당 인용출량을 반응조 특성에 맞게 보정하여 시뮬레이션을 실시한 결과와 pilot plant 실측치가 유사한 것으로 나타났다.

• 유기물자원화
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• 제21권3호
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• pp.82-92
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• 2013

생물학적 질소 및 인을 제거하기 위한 경제적인 공법인 간헐 폭기 MBR공법은 내부순환이 없고, 간헐반응조 폭기 시간 조절을 통해서 반응시간을 조절할 수 있는 장점이 있다. 본 연구에서는 신기술로 인증 받은 폭기에너지 절약 공법인 신 간헐폭기-MBR공법, 그리고 간헐반응조 폭기/비포기 주기가 1시간/1시간 및 4시간/4시간인 일반적인 간헐 폭기 MBR공법에 있어서의 처리성을 컴퓨터시뮬레이션을 통해서 평가하였다. 폭기 주기가 1시간/1시간인 간헐폭기 MBR공법의 경우, 폭기 시 최대 용존산소 농도가 0.23mg/L가 되어, 동시 질산화/탈질 반응이 수행되는 것으로 나타나 질소와 인 제거 효율은 각각 57.0%, 55.0%로 가장 높았다. 본 연구는 유입수질이 일정한 경우에 있어서의 시뮬레이션을 수행하였으며, 각 시스템에 있어서의 실 처리장 적용성을 파악하기 위해서는 유입수질 변동에 따른 처리성을 평가할 필요가 있는 것으로 나타났다.

• 한국물환경학회지
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• 제18권2호
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• pp.123-130
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• 2002

Bench scale experiments were carried out with two biological nutrient removal(BNR) units, A/O and $A^2O$ processes, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in two BNR processes. To achieve this goal, COD/T-P and COD/TKN ratios of the influent was varied in the range of 23~64 and 5~24, respectively. In A/O process, influent COD/T-P ratio should be kept higher than 44mg/L to meet the final effluent T-P concentration lower than 1mg/L and in $A^2/O$ process, influent COD/T-P and COD/TKN ratios higher than 56 and 10, respectively, were required for good phosphorus release and uptake with no influence of nitrate nitrogen in return sludge. At this conditions, the rate of phosphorus release in the anaerobic basin should be kept higher than 0.1 kg S-P/kg MLVSS d In A/O process, the phosphorus content of anaerobic and aerobic sludges was increased as SRT of total system was becoming longer resulting in decreasing the difference of phosphorus content between two sludges while phosphorus release in anaerobic basin and phosphorus uptake in aerobic basin was not incident. In $A^2/O$ process, the phosphorus content of anaerobic and aerobic sludges were not increased with higher SRT of total system due to the relatively high nitrate concentration in return sludge. However, the difference of phosphorus content between anaerobic and aerobic sludges was incident when phosphorus release and uptake was observed.

• 한국물환경학회지
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• 제25권6호
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• pp.872-878
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• 2009

Advanced Phase Isolation Ditch (APID) process was studied to develop economic retrofitting technology, for the plants where retrofitting of common activated sludge process is required. In this study, to develop and apply the modified intermittently aeration mode as process control conditions for treating municipal wastewater, a demonstration plant was installed and operated in the existing sewage treatment plant of P city. During this study, the average effluent $BOD_5$, SS, T-N, and T-P concentrations were 6.3, 4.5, 10.0, and 1.3 mg/L. The modified mode decreased the nitrification capability more than the conventional mode in the application period. Nitrate in the anaerobic condition can have a negative effect on biological phosphorus removal. In the decreasing nitrate levels, the modified mode increased the biological ability of removal phosphorus more than the conventional mode in this study. Therefore, newly developed APID process with modified intermittent aeration mode can be one of the useful processes for stable organic matter and nutrients removal.

• Membrane and Water Treatment
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• 제9권3호
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• pp.155-162
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• 2018

Process modeling with activated sludge models (ASMs) is useful for the design and operational improvement of biological nutrient removal (BNR) processes. Effective utilization of ASMs requires the influent fraction analysis (IFA) of the wastewater treatment plant (WWTP). However, this is difficult due to the time and cost involved in the design and operation steps, thereby declining the simulation reliability. Harmony Search (HS) algorithm was utilized herein to determine the relationships between composite variables and state variables of the model IWA ASM1. Influent fraction analysis was used in estimating fractions of the state variables of the WWTP influent and its application to 9 wastewater treatment processes in South Korea. The results of influent $S_s$ and $Xs+X_{BH}$, which are the most sensitive variables for design of activated sludge process, are estimated within the error ranges of 8.9-14.2% and 3.8-6.4%, respectively. Utilizing the chemical oxygen demand (COD) fraction analysis for influent wastewater, it was possible to predict the concentrations of treated organic matter and nitrogen in 9 full scale BNR processes with high accuracy. In addition, the results of daily influent fraction analysis (D-IFA) method were superior to those of the constant influent fraction analysis (C-IFA) method.

• 한국환경농학회지
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• 제28권4호
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• pp.371-377
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• 2009

In this study, simultaneous nitrification and denitrification (SND) from synthetic wastewater were performed to evaluate dissolved oxygen(DO) effects on chemical oxygen demand(COD) and nitrogen removal in a single membarne bio-reactor(MBR). DO levels in MBR at Run 1, 2, and 3 were 1.9~2.2, 1.3~1.6, and 0.7~1.0 mg/L, respectively. Experimental results indicated that DO had an important factor to affect COD and total nitrogen(TN) removal. SND were able to be accomplished in the continuous-aeration MBR by controlling ambient DO concentration. It is postulated that, because of the oxygen diffusion limitation, an anoxic micro-zone was formed inside the flocs where the denitrification might occur. From the results of this study, 96% of COD could be removed at DO of 0.7mg/L. At run 2 72.92% of nitrogen was removed by the mechanisms of SND (7.75mg-TN/L in effluent). In this study, SND was successfully occurred in a MBR due to high MLSS that could help to form anoxic zone inside microbial floc at bulk DO concentrations of 1.3~1.6mg/L.