• 환경위생공학
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• 제23권4호
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• pp.55-64
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• 2008

In this study, the management and improvement of public small-scale sewage treatment facilities was investigated. In order to improve the effective management of the operation of small-scale sewage treatment facilities, treatment methods and the problems associated with sewage treatment were carefully addressed based on the data and literature. The investigation results showed that sewer pipes in rural areas should be repaired to prevent sewage from leaking and small-scale operations should be required to have effective management for pollutant loads less than 50%. Also, new methods should be developed for low concentrations of sewage. A law associated with FRP treatment facilities should be established and local governments need to supervise these operations to avoid insufficient and faulty construction. It is recommended that new facilities are built with advanced treatment techniques when the old facility can not comply with nitrogen and phosphorous discharge limits. Moreover, the study shows that nutrient and coliform treatment efficiency improves when abandoned facilities are renovated with the installation of nitrification/denitrification and disinfection processes or another advanced process.

• 한국물환경학회지
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• 제22권2호
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• pp.209-214
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• 2006

The purpose of this study is to improve the stream water quality by the experimental hybrid constructed wetland system. It consisted of the water layer, sand bed planted reeds, irises and roses, gravel bed, yellow-soil media bed and a flow shifter (FS) which can reverse top and bottom flow in the middle of the wetland. The organic compounds and nitrogen removal efficiencies varied with the seasons, namely temperature change. In summer, the mean efficiencies of COD and TN in the outflow from this wetland system were 63.4 and 48.0% and shown the highest, respectively, whereas, the suspended solids and phosphorus removal efficiencies seemed to be less affected by temperature. As a result of inspecting the decreasing trend of pollutants, nitrification-denitrification in the wetland was the major removal mechanism for nitrogen, the nitrogen reduction was especially enhanced by the application of a FS in the wetland, and phosphorus reduction was mainly occurred as a consequence of adsorption of the yellow-soil media.

• 한국물환경학회지
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• 제26권1호
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• pp.19-27
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• 2010

Submerged plants whose most of vegetative mass are below the water surface can have great effects on wetland biogeochemistry and water purification through their photosynthesis and nutrient uptake processes. In this study, change of dissolved oxygen concentration and pH as well as nutrient removal capacity of the submerged plant dominant wetland were investigated using wetland mesocosm experiments. Obvious periodic DO and pH fluctuation was observed due to photosynthetic activities of the submerged plants. It implies that the submerged plants can provide periodic or sequential changes of oxic and anoxic conditions that affect nitrification and denitrification processes and contribute permanent nitrogen removal in the wetland system. The pH changes in the wetland mesocosm suggested that submerged plant could also play an important role as a temporary $CO_2$ storage. Higher nutrient removal efficiency was observed in the submerged plant dominant wetland mesocosm. The removal efficiencies under experimental conditions were 38.89, 84.70, 91.21, 70.76, 75.30% of TN, DIN, $NH_4-N$, TP, $PO_4-P$ in the wetland mesocosm, while those were 26.11, 57.34, 63.87, 28.19, 55.15% in the control treatment, respectively.

• 한국물환경학회지
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• 제33권1호
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• pp.63-69
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• 2017

Small size privately owned wastewater treatment plants have been difficult to treat their wasted sludge and maintain steady effluent quality compared with publicly owned wastewater treatment plants. Therefore, this study has focused on treatment efficiency enhancement, specially nitrogen removal efficiency by recycling dewatering filtrate as an alkalinity additive from filter press using $CaCO_3$. As the result, it was found that the optimal mixing ratio between the excess sludge and $CaCO_3$ was 1:2. The major operation parameters such as specific substrate utilization rate, specific nitrification rate, and specific denitrification rate were also improved 64% ($0.048-0.079mg\;BOD_5/mg\;MLVSS{\cdot}day$), 35% ($0.020-0.027mg\;NH_3-N/mg\;MLVSS{\cdot}day$) and 68% ($0.051-0.086mg\;NO_3{^-}-N/mg\;MLVSS{\cdot}day$), respectively, after the adoption of new methods. Therefore, both the problem of sludge treatment at small scale plants and the need for efficiency improvement could be solved.

• 물과 미래
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• 제22권1호
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• pp.117-125
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• 1989

본 연구는 활성슬러지공법을 변형시킨 무산소일염기일호기반응조를 사용해서 질산화일탈질소반응 및 인의 방출인초과축적반응을 유도하여 합성페수의 유기물, 질소 및 인을 동시에 제거하였다. 무질소조, 무염기 및 호기호 각각에 대한 반응특성을 조사하기 위해 실험실규모의 반응조가 운영되었으며 MLSS농도를 5000, 4200, 3300, 2600, 1900mg/l로, 변화시켜 COD제거율에 대한 생물학적 동력학계수를 결정하였다. 연구결과, 유기물 및 영양염이 변형된 슬러지공법에 의해 동시에 제거될 수 있음을 알았고, ortho-p 제거효율은 66%∼99%로 높게 나타났다.

• 공업화학
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• 제21권3호
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• pp.243-251
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• 2010

연소배가스에 존재하는 질소산화물의 제거를 위해서는 촉매 환원, 흡수, 흡착 등 화학적 기술이 적용되고 있는데, 장기적으로는 환경친화적이고 에너지 소모가 적은 생물학적 공정의 개발 및 이용이 필요하다. 본 논문에서는 연소 배가스에 존재하는 질소산화물을 제거하기 위한 생물학적 공정의 기술동향을 살펴보고 각각의 장단점을 고찰하였다. 질산화와 탈질 기작을 이용하는 박테리아 시스템과 광합성 미세조류를 이용하는 시스템으로 구분하여 기술의 원리와 현재의 기술 수준을 논하였다. 두 경우 모두 처리속도를 높이기 위해서는 불용성의 일산화질소를 일단 적절한 흡수제에 고농도로 포집시킨 후 미생물에 의하여 분해 또는 고정하는 방향이 바람직하며, 배가스 중 $CO_2$와 NOx를 동시에 고정이 가능하고 별도의 탄소원이 요구되지 않는 미세조류의 활용이 기대된다.

• 상하수도학회지
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• 제17권4호
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• pp.559-566
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• 2003

From this research, the performances of a sludge reduction in the sewage sludge aerobic digestion was experimented by using a sludge pretreatment and membrane bioreactor. The submerged plate membrane was used as the solid-liquid separation membrane. After drawing small amounts of sludge in a bioreactor and then doing the alkaline treatment and ozone treatment, the sludge was sent to back to the reactor. The HRT in the reactor was set as 5 days and the operation in the reactor was carried out at the DO of 1mg/L on average. After 100 days of operation in the reactor, it was shown that the reduction efficiency of total solids was more than 83%. Most of volatile solids were removed through mineralization, and the considerable portion of the non-volatile solids was dissolved and then flowed out with the effluent. Only about 16.3% of total solids in the sludge was accmulated in the reactor even without the loss of volatile fraction. Also, by deriving nitrification and denitrification in one reactor simultaneously, more than 90% of nitrogen removal effect was realized and the experiment was run smoothly without fouling of membrane, even in the high concentration of MLSS. Based on this experiment, sludge can be reduced considerably at a low HRT by these two newly suggested approach.

• 한국환경과학회지
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• 제16권7호
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• pp.813-821
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• 2007

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus in two sequencing batch biofilm reactors (SBBRs). SBBR1 had a short first non-aeration period and SBBR2 had a long first non-aeration period. The removal characteristics of nitrogen and phosphorus in each SBBR were precisely observed according to the variation of influent TOC concentration, and the operation control parameters (pH, DO concentration, ORP) in each reactor were measured. In biological nitrogen removal, there was little difference between SBBR1 and SBBR2 and the nitrogen removal efficiencies were very low. The nitrogen and phosphorus removal characteristics in high influent TOC concentration were different from those in low TOC. Nitrogen removals by simultaneous nitrification/denitrification (SND) were occurred in both SBBR1 and SBBR2. The P removal in SBBR1 was superior to that in SBBR2. The second P release was observed in SBBR1 which had long second non-aeration period.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2479-2481
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• 2000

It is the time-varying dissolved oxygen(DO) dynamics that requires controlling for maintaining the DO concentration in the aeration tank. Many linear controllers have thus been applied. Because of the nonlinearity of the oxygen transfer function together with the time-varying respiration rate, however, the linear controllers are found to poorly perform in many cases. To overcome this limitation, a number of advanced controlling techniques have been developed and applied. In this study, designed GA-PI Controller using genetic algorithm(GA). Genetic algorithms(GAs) are search algorithms based on the mechanics of natural selection and natural genetics. As result of computer simulation, GA-PI controller shows the better control performance especially under the condition of the continuously changing DO set-point. This result represents that GA-PI controller can be a good measure to control the DO concentration in the SBR process which requires the sequential DO set-point change to accomplish the nitrification and denitrification in a single reactor.

• 한국환경보건학회지
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• 제31권2호
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• pp.152-159
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• 2005

Laboratory scale experiments were conducted to study the applicability, and to compare the performance of two types of sequencing batch reactor (SBR)systems, a conventional SBR and sequencing batch biofilm reactor (SBBR) on the biological nitrogen and phosphorus removal. The nitrification rate in SaR was higher than that in SBBR both in high influent TOC concentration. The denitrification was completed at the first non-aeration period in SBR, however, the additional non-aeration period should be installed or the first aeration period should be extended more in order to complete the nitrogen removal in SBBR. The time at the first aeration period was more needed as about 4-5 h in order to uptake all the released $PO_4^{3-}\;-P$ at the first non-aeration period. SBBR needed more operation time, especially the first aeration time, than SBR at the high influent TOC concentration in order to complete nitrogen and phosphorus removal.