• 한국물환경학회지
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• 제24권1호
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• pp.54-62
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• 2008

It is often believed that a more complex water quality model is better able to simulate reality. The more complex a model, however, the more parameters are involved thus increases the cost and uncertainty of modeling processes. The objective of this study was to compare the performance of two steady-state river water quality models, QUAL2E and QUAL-NIER, that have different complexity. QUAL-NIER is recently developed by National Institute of Environmental Research aiming to enhance the simulation capability of QUAL2E for eutrophic rivers. It is a carbon based model that considers different forms, such as dissolved versus particulate and labile versus refractory, of carbon and nutrients, and the contribution of autochthonous loading due to algal metabolism. The models were simultaneously applied to Nakdong River and their performance was evaluated by statistical verification with field data. Both models showed similar performance and satisfactorily replicated the longitudinal variations of BOD, T-N, T-P, Chl.a concentrations along the river. The algal blooms occurred at the stagnant reaches of downstream were also reasonably captured by the models. Although QUAL-NIER somewhat reduced the magnitude of errors, the hypothesis tests revealed no statistical evidence to justify its better performance. The contribution of autochthonous carbon and nutrient load by algal metabolism was insignificant because the hydraulic retention time is relatively short compare to the time scale of kinetic reactions. The results imply that the kinetic processes included in QUAL-NIER are too complex for the nature and scale of the real processes involved, thus needs to be optimized for improving the modeling efficiency.

• 한국수산과학회지
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• 제35권4호
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• pp.356-365
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• 2002

One of the most important factors that cause eutrophication is nutrient materials containing nitrogen and phosphorus which stem from excreation of terrestial sources and release from sediment. Therefore, to improve water quality, the reduction of these nutrients loads should be indispensible. At this study, the three-dimensional numerical hydrodynamic and ecosystem model, which was developed by Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the eutrophication. The residual currents, which were obtained by integrating the simulated tidal currents over 1 tidal cycle, showed the presence of a typical counterclockwise eddies between Gyewha and Garyuk island. Density driven currents were generated westward at surface and eastward at the bottom in Saemankeum area where the fresh waters are flowing into, The ecosystem model was calibrated with the data surveyed in the field of the study area in annual average. The simulated results were fairly good coincided with the observed values within relative error of $30\%$. The simulations of DIN and DIP concentrations were performed using ecosystem model under the conditions of $40\~100\%$ pollution load reductions from pollution sources. In study area, concentration of DIN and DIP were reduced to $59\%$ and $28\%$ in case of the $80\%$ reduction of the input loads from fresh water respectively. But pollution loads from sediment had hardly affected DIN and DIP concentration, The $95\%$ input load abatement is necessary to meet the DIN and DIP concentration of second grade of ocean water quality criteria.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.1079-1083
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• 2010

하절기에 집중되는 강우로 인해 국내의 경우 저수지와 댐 건설이 불가피 하였으며, 이들 구조물에 의한 수체의 거동 및 수질의 분포 또한 일반 하천과는 다른 특성을 지니고 있다. 특히, 흐름 방향보다 수심 방향으로의 특성이 강하게 작용하는 호소에서는 3차원 수리 수질 모델링을 적용함으로써 모의 결과에 대한 신뢰성을 높일 수 있다. 하천의 발원지로서의 댐(저수지)과 하천과 하천사이에 위치한 저수지의 특성이 다르며, 하천 사이에 위치한 저수지의 경우, 하천과 하천을 이어주며 그 흐름특성과 수질의 분포 및 변화의 양상의 바뀐다는 점에서 독립적이며, 연계되는 구조의 특징을 동시에 반영할 수 있어야 한다. 본 논문에서는 낙동강에 위치한 남강댐(진양호)를 중심으로 연구를 진행하였으며, 안동댐 등처럼 하천의 발원지가 아닌 하천과 하천 사이에 위치한 호소(댐)으로 이와 같은 특징을 반영하여 수질오염총량관리제에서의 목표수질 달성여부와 점 및 비점오염원에서 발생되는 오염부하량의 변화에 따른 저수지 내의 수리 수질 모의를 EFDC-WASP의 연계 모델을 통해 연구하고자 하였다.

• 한국물환경학회지
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• 제37권1호
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• pp.47-54
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• 2021

Aerobic granular sludge (AGS) can be classified as a type of self-immobilized microbial aggregates measuring more than 0.2 mm. It offers the option to simultaneously remove COD, N, and P that occur in different zones inside a granule. Also, AGS is characterized by high precipitability, treatability with high organic loading, and high tolerance to low temperature. In this study, a sequencing batch reactor inoculated with AGS (AGS-SBR) is a new advanced wastewater treatment process that was proven to grow AGS with integrated nutrient removal and low C/N ratio. A pilot plant, AGS-SBR with a capacity of 225 ㎥/d was installed at an S sewage treatment plant in Gyeonggi-do. The results of the operation showed that the water quality of the effluent indicated that the value of BOD5 was 1.5 mg/L, CODMn was 11.4 mg/L, SS was 6.2 mg/L, T-N was 13.2 mg/L, and T-P was 0.197 mg/L, and all of these values reliably satisfied an effluent standard (I Area). In winter, the T-N treatment efficiency at a lower temperature of less than 11℃ also showed reliability to meet the effluent standard of the I Area (20 mg/L or less). Analysis of microbial community in AGS showed a higher preponderance of beneficial microorganisms involved in denitrification and phosphorus accumulation compared with activated sludge. The power consumption and sludge disposal cost were reduced by 34.7% and 54.9%, respectively, compared to the domestic SBR type sewage treatment plant with a processing capacity of 1,000 ㎥/d or less.

• Ecology and Resilient Infrastructure
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• 제8권4호
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• pp.245-252
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• 2021

하천이나 호소에서 발생하는 탁도 흐름은 유역유사유출 과정에서 부유사와 같이 다양한 영양물질이 혼합된 물질 순환의 결과물로 취수나 하천환경 등에 영향을 미치는 원인이 된다. 본 연구는 낙동강 본류를 대상으로 일차원 비정상(time-variant) 수치모형의 Python 코드를 개발하였다. 개발모형의 수치 안정성을 검토하였으며 모형의 적용성을 시험하기 위해 비홍수기의 준정상류 흐름에 대하여 낙동강 본류의 상류 탁도와 지류의 탁도 변화가 반영된 3가지 모의조건으로 적용하였다. 적용 결과, 각 모의 조건에 대해 물질 보존 관점에서 합리적인 수치해석 결과를 얻을 수 있었으며 향후 현장에서 실측된 지점 또는 하도 구간 내의 탁도 유동 자료을 확보할 수 있다면 대하천에 적용 가능한 탁도 간략 예측모형으로 활용할 수 있을 것이다.

• Journal of Microbiology and Biotechnology
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• 제33권10호
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• pp.1337-1350
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• 2023

Caproic acid is a precursor substance for the synthesis of ethyl caproate, the main flavor substance of nongxiangxing baijiu liquor. In this study, Clostridium butyricum GD1-1, a strain with high caproic acid concentration (3.86 g/l), was isolated from the storage pit mud of nongxiangxing baijiu for sequencing and analysis. The strain's genome was 3,840,048 bp in length with 4,050 open reading frames. In addition, virulence factor annotation analysis showed C. butyricum GD1-1 to be safe at the genetic level. However, the annotation results using the Kyoto Encyclopedia of Genes and Genomes Automatic Annotation Server predicted a deficiency in the strain's synthesis of alanine, methionine, and biotin. These results were confirmed by essential nutrient factor validation experiments. Furthermore, the optimized medium conditions for caproic acid concentration by strain GD1-1 were (g/l): glucose 30, NaCl 5, yeast extract 10, peptone 10, beef paste 10, sodium acetate 11, L-cysteine 0.6, biotin 0.004, starch 2, and 2.0% ethanol. The optimized fermentation conditions for caproic acid production by C. butyricum GD1-1 on a single-factor basis were: 5% inoculum volume, 35℃, pH 7, and 90% loading volume. Under optimal conditions, the caproic acid concentration of strain GD1-1 reached 5.42 g/l, which was 1.40 times higher than the initial concentration. C. butyricum GD1-1 could be further used in caproic acid production, NXXB pit mud strengthening and maintenance, and artificial pit mud preparation.

• Asian-Australasian Journal of Animal Sciences
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• 제17권11호
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• pp.1615-1634
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• 2004

A review was undertaken to obtain information on the sustainability of pig free-range production systems including the management, performance and health of pigs in the system. Modern outdoor rearing systems requires simple portable and flexible housing with low cost fencing. Local pig breeds and outdoor-adapted breeds for certain environment are generally more suitable for free-range systems. Free-range farms should be located in a low rainfall area and paddocks should be relatively flat, with light topsoil overlying free-draining subsoil with the absence of sharp stones that can cause foot damage. Huts or shelters are crucial for protecting pigs from direct sun burn and heat stress, especially when shade from trees and other facilities is not available. Pigs commonly graze on strip pastures and are rotated between paddocks. The zones of thermal comfort for the sow and piglet differ markedly; between 12-22$^{\circ}C$ for the sow and 30-37$^{\circ}C$ for piglets. Offering wallows for free-range pigs meets their behavioural requirements, and also overcomes the effects of high ambient temperatures on feed intake. Pigs can increase their evaporative heat loss via an increase in the proportion of wet skin by using a wallow, or through water drips and spray. Mud from wallows can also coat the skin of pigs, preventing sunburn. Under grazing conditions, it is difficult to control the fibre intake of pigs although a high energy, low fibre diet can be used. In some countries outdoor sows are fitted with nose rings to prevent them from uprooting the grass. This reduces nutrient leaching of the land due to less rooting. In general, free-range pigs have a higher mortality compared to intensively housed pigs. Many factors can contribute to the death of the piglet including crushing, disease, heat stress and poor nutrition. With successful management, free-range pigs can have similar production to door pigs, although the growth rate of the litters is affected by season. Piglets grow quicker indoors during the cold season compared to outdoor systems. Pigs reared outdoors show calmer behaviour. Aggressive interactions during feeding are lower compared to indoor pigs while outdoor sows are more active than indoor sows. Outdoor pigs have a higher parasite burden, which increases the nutrient requirement for maintenance and reduces their feed utilization efficiency. Parasite infections in free-range pigs also risks the image of free-range pork as a clean and safe product. Diseases can be controlled to a certain degree by grazing management. Frequent rotation is required although most farmers are keeping their pigs for a longer period before rotating. The concept of using pasture species to minimise nematode infections in grazing pigs looks promising. Plants that can be grown locally and used as part of the normal feeding regime are most likely to be acceptable to farmers, particularly organic farmers. However, one of the key concerns from the public for free-range pig production system is the impact on the environment. In the past, the pigs were held in the same paddock at a high stocking rate, which resulted in damage to the vegetation, nutrient loading in the soil, nitrate leaching and gas emission. To avoid this, outdoor pigs should be integrated in the cropping pasture system, the stock should be mobile and stocking rate related to the amount of feed given to the animals.

• 생태와환경
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• 제40권2호
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• pp.201-213
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• 2007

본 연구에서는 북한강 상류 지역인 소양강댐 유역에 BASINS/WinHSPF모델을 적용하였다. WinHSPF는 도시와 농촌지역 등이 혼재된 토지이용형태를 보이는 유역에 적용하기 적합한 모델로서, 산림이 대부분인 소양강댐 유역의 유출량 및 수질을 모의하고, 유역의 오염부하량을 분석하였다. 또한, 유역관리를 위해 인공습지와 저류지를 설치하였을 경우 WinHSPF의 Best Management Practice Evaluation(BMPRAC)을 통한 오염부하 삭감량을 산정하였다. WinHSPF 모델을 이용하여 유출량은 2000년부터 2004년까지, 수질 항목은 1990년부터 2004년가지 모의하였다. 모델 보정 결과 유량의 변화는 인북천, 북천, 내린천 세 곳 모두 강수량의 변화와 일치하여 변화하는 경향을 나타내고 있었고 모의치가 실측치를 대체적으로 잘 반영하였지만 유출량이 피크인 경우에 실측지에 비해 과소평가 되는 경향을 나타내었다. 이는 각 소유역에서 발생하는 강우량을 이용하여 모델을 구동한 것이 아니고, 일부 국한된 기상관측소의 자료만을 이용하였기 때문에 지역적인 차이가 나타났거나, 수위-유량 곡선을 통해 유출량을 산정하는 과정에서 수위가 높은 시기에 유량이 과도하게 계산된 경우가 있기 때문이라 판단된다. 수질항목은 온도, DO, BOD의 경우 예측값이 연중 수질변화패턴을 잘 반영하였다. TN과 TP는 모의치가 다소 과대, 과소평가되는 경향이 있었는데, 향후 보다 효율적인 유역관리를 위한 모델의 활용을 위해서는 정확하고 자세한 기상자료와 수문자료가 뒷받침되어야 하며, 실측지점의 특성을 대표할 수 있는 수질 및 유출량 측정이 이루어져야 할 것이다. 2000년부터 2004년가지 소양강댐 유역의 오염부하량은 강우량이 가장 논은 2003년에 BOD, TN, TP가 각각 4,109,674 kg $yr^{-1}$, 6,457,315 kg $yr^{-1}$, 104,186 kg $yr^{-1}$로 가장 높게 나타났다. 월별 부하량은 7월부터 9월에 배출되는 양이 BOD는 약 63.5%, TN 약 64.1%, TP는 약 64.4%를 차지하여, 강우 시 유출량이 증가하면 부하량도 비례하여 증가는 것으로, 강우 유출량에 많은 영향을 받고 있는 것으로 나타났다. 인북천, 북천, 내린천, 소양강 유역에서 BOD, TN, TP의 오염부하량은 약 98% 이상이 비점오염원으로부터 발생하는 것으로 분석되었는데, 이는 유역의 대부분이 산지와 농경지로서 산업시설과 같은 점오염원이 적고,강우 시 산림지역 및 농경지에서 많은 양의 비점오염원이 발생하기 때문으로 판단된다. WinHSPF모델의 BMPRAC를 이용하여 Scenario를 적용한 결과 부하량 삭감율은 저류지를 설치한 scenario 2가 가장 많이 감소하는 것으로 나타났다. 강우기(7${\sim}$9월)의 부하량 삭감율은 BOD의 경우 Scenario 1-1(처리용량 1,500 $m^3$ $day^{-1}$인 인공습지), scenario 1-2 (처리용량 1,000 $m^3$ $day^{-1}$인 인공습지), scenario 2(면적 4.2ha인 저류지)가 각각 연평균 6.9%, 4.8%, 7.1%의 감소를 보였다. TN은 4.7%, 3.4%, 13.4%의 삭감율을 나타내었으며, TP는 5.6%, 3.9%, 7.3%의 삭감율을 나타내었다. 본 연구에서는 적용하지 못하였으나, 인공습지와 저류지의 적절한 연계시스템을 적용한다면 저감시설 설치 부지면적과 비용의 감소뿐만 아니라 보다 효과적인 수질개선효과를 가져올 수 있으리라 판단된다.

• 한국환경생태학회지
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• 제23권6호
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• pp.569-576
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• 2009

산림벌채와 농경지 개발에 의한 토사와 영양염류의 유출은 시라루토로호수의 생물서식지 환경을 악화시키고 있다. 산림벌채와 농업활동이 수질에 미치는 영향을 조사하기 위해 산림벌채와 농경지 개발에 의한 토사와 영양염류의 유출은 시라루토로호수의 생물서식지 환경을 악화시키고 있다. 산림벌채와 농업활동이 수질에 미치는 영향을 조사하기 위해 토지이용에 따른 총질소와 총인의 변화를 분석하고, 이들의 분석 결과를 다른 연구자료와 비교하였다. 호수의 총질소와 총인은 산림면적 증가에 따라 감소하고, 농지면적이 증가하면 높은 농도를 나타내었다. 그러나 시라루토로호수의 수질은 좁은 농지면적과 넓은 산림으로 둘러싸여 있음에도 불구하고 총질소와 총인의 농도가 높게 나타났다. 이는 유역의 토지이용이 호수에 인접한 곳에서 행해지고 있어 호수 수질에 영향을 미친 것으로 사료되었다. 토지이용에 따른 유역의 토사생산량 변화를 추정하기 위해 호수 토사퇴적물 시료 11개를 채취하여 약 300년 동안의 토사동태를 조사하였다. 채취한 호수 퇴적물에는 2개의 화산재층(1694년의 Ko-c2층 과 1739년의 Ta-a층)과 세슘($^{137}Cs$)피크(1963년)가 존재하였고, 이들의 연대를 이용하여 약 300년간 유역의 토사생산량을 분석하였다. 초기개발기(1694~1739과 1739~1963)에는 8.4~8.9 tons/$km^2$/year의 토사가 유역으로부터 생산되었고, 1960년대 이후 산림벌채와 농지개발로 인하여 21.1 tons/$km^2$/year(1963~2007)으로 토사생산량이 증가하였다.

• 한국토양비료학회지
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• 제43권2호
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• pp.132-139
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• 2010

To manage the effluent nutrients amounts from rice paddy fields using free range ducks or rice bran, we evaluated the effects of a purifying paddy field which is no fertilizer, no pesticides, and dense rice seedling having a concept of constructed wetland. The experimental paddy field was located at downstream in the watershed of ducks using rice culture area in Milyang. The purifying paddy of land design were treated with seeding method, and vegetation type. As land design, direct seeding on plane, and direct seeding on high-ridge field in 2007. Planting rice only, and planting rice with water hyacinth were treated as vegetation type in purifying paddy in 2008. The purifying paddy fields were effective to reduce amount of T-N and T-P contents in effluent to 33.2~45.3%, and 53.1~55.4%, respectively. The direct seeding on high-ridge treatment, having long residence time of effluent water was more effective than plane plot as T-N 0.29 $g^{-1}m^{-2}d^{-1}$, and T-P 0.031 $g^{-1}m^{-2}d^{-1}$. The planting rice with water hyacinth treatment was effective than planting rice only as T-N 0.23 $g^{-1}m^{-2}d^{-1}$, and T-P 0.049 $g^{-1}m^{-2}d^{-1}$. The optimum area of purifying paddy field to treats all effluent were found out 3.2~4.7% of rice culture area using free range ducks, and rice bran at upper stream.