• 상하수도학회지
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• 제31권2호
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• pp.161-168
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• 2017

Microfiltration (MF) and Ultrafiltration (UF) membrane processes capable of producing highly purified water have been extensively applied as a pretreatment process in the wastewater reuse field with the improvement of membrane properties and resistance, development of operating protocols, and improvement of technologies of backwashing and physicochemical cleaning, and improvement of scale and antifoulants. However, despite of the development of membrane production and process technologies, fouling still remains unresolved. This study confirmed that foulants such as polysaccharides, proteins and humic substances existed in final treated effluent (secondary effluent) by fluorescence excitation emission matrix (FEEM) and fourier transform infrared spectroscopy (FTIR) analysis. In addition, when constructing ozone oxidation and coagulation processes as a hybrid process, the removal efficiency was 5.8%, 6.9%, 5.9%, and 28.2% higher than that of the single process using coagulation in turbidity, color, dissolved organic carbon (DOC), and UV254, respectively. The reversible and irreversible resistances in applying the hybrid process consisting of ozone oxidation and coagulation processes were lower than those in applying ozone oxidation and coagulation processes separately in UF membrane process. Therefore, it is considered possible to apply ozonation/coagulation as a pretreatment process for stable wastewater reuse by and then contributing to the reduction of fouling when calculating the optimal conditions for ozone oxidation and coagulation and then to applying them to membrane processes.

• 한국농공학회논문집
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• 제55권3호
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• pp.91-104
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• 2013

The objectives of this study were to monitor and assess the environmental impacts of indirect wastewater reuse on water quality and soil in paddy fields. Yongin monitoring site (YI) irrigated from agricultural reservoir and Osan monitoring site (OS) irrigated with treated wastewater diluted with stream water were selected as control and treatment, respectively. Monitoring results for irrigation water quality showed a significant statistical difference in salinity, exchangeable cation and nutrients. Pond water quality showed a similar tendency with irrigation water except for the decreased difference in nutrients due to the fertilization impact. Soil chemical properties mainly influenced by fertilization activity such as T-N, T-P, and $P_2O_5$ were changed similarly in soil profiles of both monitoring sites, while the properties, EC, Ca, Mg, and Na, mainly effected by irrigation water quality showed a considerable change with time and soil depth in treatment plots. Heavy metal contents in paddy soil of both control and treatment did not exceed the soil contamination warning standards. This study could contribute to suggest the irrigation water quality standards and proper agricultural practices including fertilization for indirect wastewater reuse, although long-term monitoring is needed to get more scientific results.

• 생태와환경
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• 제35권2호통권98호
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• pp.133-140
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• 2002

본 연구는 실험실규모의 산화지 공법을 적용하였다. 체류시간 변화 및 산화지 형태가 처리율에 미치는 영향을 조사하였다. 조류의 광합성에 대한 유기물 제거율과 용존산소와의 상관관계는 야간에 비해 주간의 상관성이 더 높은 것으로 나타났고, 단일지의 경우는 체류시간 15일의 경우가 5일에 비해 상관성이 더 높은 것으로 조사되었다. 시간대별 DO변화는 체류시간 5일의 경우 다단산화지 내의 DO농포는 $42{\sim}19.8\;mg/l$를 나타내었고, 첫번째 조에 비해 후단으로 갈수록 높아졌다. 유기물 처리효율은 체류시간 5일이고, 4단 직렬식 다단 산화지 시설에서 제거효율이 더 높았다. 유기물 제거효율로 $TBOD_5$ 평균 제거율은 $49{\sim}83%$를 나타내었고, $SBOD_5$의 경우는 $87{\sim}92%$의 높은 처리율을 나타내었다. 또한 산화지내 조류생성량을 일정 농도로 유지시켜 주는 것이 산화지 공법의 처리율을 높일 수 있는 것으로 나타났다.

• 한국농공학회논문집
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• 제53권4호
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• pp.67-74
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• 2011

The objectives of this study were to assess the rice yields and evaluate fertilizer reduction effect of reclaimed wastewater irrigation in paddy fields using the Decision Support System for Agrotechnology Transfer (DSSAT) v4.5 model. The experimental plots were designed, which was located near the Suwon wastewater treatment plant in Gyeonggi-do, Korea. The rice yield, irrigation amount, irrigation water quality and soil data were monitored and collected between 2006 and 2009. The DSSAT model was calibrated and validated with observed data. The methods that were used to evaluate this model were the root mean square error (RMSE), normalized root mean square error (nRMSE), and index of agreement (d). The values of RMSE, nRMSE, and d ranged from 145 to $789\;kg\;ha^{-1}$, 3.0 to 13.3 %, and 0.90 to 0.95 for the calibration period, respectively and represented from 91 to $538\;kg\;ha^{-1}$, 2.0 to 10.4 %, 0.94 to 0.98 for the validation period, respectively. Overall, this model showed good agreement with observed data of rice yields irrigated with reclaimed wastewater. The fertilizer reduction effect in paddy field of reclaimed wastewater irrigation was assessed about 60 % in 2008 and 40 % in 2009.

• 한국환경과학회지
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• 제16권10호
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• pp.1169-1177
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• 2007

The main objective of this research was to evaluate the effects of process variables which were forming ability, flow displacement, effective stress, effective strain, fluid vector and products defects on manufactured artificial lightweight aggregate made of both incinerated sewage sludge ash and clay by means of the numerical analysis of a rigid-plastic finite element method. CATIA (3D CAD program) was used for an extrusion metal mold design that was widely used in designing aircraft, automobile and metallic molds. A metal forming analysis program (ATES Co.) had a function of a rigid-plastic finite element method was used to analyze the program. The result of extrusion forming analysis indicated clearly that a shape retention of the manufactured artificial light-weight aggregate could be maintained by increasing the extrusion ratio (increasing compressive strength inside of extrusion die) and decreasing the die angle. The stress concentration of metal mold was increased by increasing an extrusion ratio, and it was higher in a junction of punch and materials, friction parts between a bottom of the punch and inside of a container, a place of die angle and a place of die of metal mold. Therefore, a heat treatment as well as a rounding treatment for stress distribution in the higher stress concentration regions were necessary to extend a lifetime of the metallic mold. A deformity of the products could have made from several factors which were a surface crack, a lack of the shape retention and a crack of inside of the products. Specially, the surface crack in the products was the most notably affected by the extrusion ratio.

• 한국지반신소재학회논문집
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• 제7권1호
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• pp.23-29
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• 2008

지오텍스타일을 활용한 탈수처리공법은 지오텍스타일의 최신 적용분야로, 여과, 배수기능을 이용하여 기 직조한 지오텍스타일 포대 내에 산업슬러지, 하수정수장 슬러지, 특히 유수지의 준설오니슬러지 등을 주입 후 자중압밀과정을 통하여 고형물단계까지 탈수처리 하는 공법이다. 본 연구에서는 폴리프로필렌과 폴리에스터 두 종류의 지오튜브(지오텍스타일)의 물리적 특성을 살펴보고, 채움재 토사의 물리적 특성에 따른 탈수 효율과, 여과 및 배수기능을 원활이 수행할 수 있는 국산 고분자 토목섬유 적용성을 분석하였다. 실내시험은 지오텍스타일과 채움 토사간의 복합적 투수 특성을 규명하기 위한 실험을 수행하였다. 현장시험은 세립질(ML-OL) 토사의 채움 시 시간에 따른 유효높이 변화를 측정하여 적절한 슬러리 비율을 도출하였다. 각종 실내 및 현장시험결과, 세립질(ML-OL) 토사의 경우 물과 토사의 혼합비율은 최소한 6:4 이상이 되어야 하며, 폴리프로필렌 재질의 지오텍스타일이 필터 및 배수기능이 우수하며, 탈수처리 공법에 더 효과적인 것으로 나타났다.

• 한국물환경학회지
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• 제20권3호
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• pp.290-295
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• 2004

In this study, ozone was adopted for the reduction and stabilization of waste sludge from the municipal sewage treatment plant. The waste sludge used in the experiments was primary sludge, excess sludge and a mixture of the two. The sludge cells and flocs were disrupted by ozonation resulting in the reduction of TSS and VSS concentrations. In the case of the primary sludge with a concentration of 20 gTS/L, the TSS and VSS concentrations were reduced 28%, 33% and the TCOD concentration was reduced 20% respectively. The consumption of ozone was $0.18gO_3/gSS$. In the case of the excess sludge with a concentration of 7.5 gTS/L, the TSS and VSS concentrations were reduced 37%, 41%, and the TCOD concentration was reduced 19% respectively. The consumption of ozone was $0.33gO_3/gSS$. In the case of the mixed sludge of 9.3 gTS/L, the TSS and VSS concentrations were reduced by 45%, 53%, and the TCOD was reduced 26% respectively. The desirable consumption of ozone was $0.27gO_3/gSS$. As ozonation proceeded, the level of SCOD increased due to the release of intracellular materials. However TCOD was reduced due to mineralization resulting from the transformation of organic materials to inorganic materials.

• 한국농공학회논문집
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• 제61권2호
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• pp.97-104
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• 2019

The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as $36.05m^3/day/ha$ and $84.45m^3/day/ha$, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

• 콘크리트학회논문집
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• 제17권1호
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• pp.3-10
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• 2005

콘크리트 구조물은 다양한 요인으로 인하여 골재노출, 탈락, 표면박리, 균열발생, 철근노출 및 부식, 강도저하, 염소이온침투, 공극률 증가, 팽창 및 수축 등과 같은 여러가지 열화현상이 나타나는 문제점을 가지고 있다. 특히 상$\cdot$하수도 시설을 포함한 수처리 구조물의 경우에는 일반적인 콘크리트 구조물보다 더욱 가혹한 환경에 노출되어있기 때문에 콘크리트의 열화는 더욱 심하다고 볼 수 있다. 본 연구는 시멘트 혼입 폴리머와 에폭시수지를 복합한 내균열성 방수$\cdot$방식재를 이용한 콘크리트구조물용 방수$\cdot$방식공법을 개발하여 실용화하는데 목적이 있다. 콘크리트구조물용 방수$\cdot$방식공법의 평가를 위하여 흡수 및 투수성, 부착성, 인장강도, 내잔갈림성, 내충격성, 냉온반복성능, 내화학성능, 음용수 용출성 등 방수$\cdot$방식재에 요구되는 성능을 평가하였다. 그 결과 KS의 규격에서 규정하는 성능기준을 모두 만족하는 것으로 나타났으며, 특히 부착성능이 우수한 것으로 확인되었다. 또한 본 탄성층을 보완한 방수$\cdot$방식공법의 적용에 의해서 최대 1.49mm까지의 균열에 대하여 저항성이 있는 것으로 평가되어 내균열성 측면에서 높은 성능을 확보하고 있는 것으로 평가되었다.

• 한국노년학
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• 제25권2호
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• pp.143-154
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• 2005

본 연구는 재가 뇌졸중 환자의 환경상태, 기능적 독립, 질병으로 인한 영향 정도를 파악하여 간호중재시의 기초자료로 활용하고자 K시와 그 인접지역에 거주하는 뇌졸중 환자 145명을 대상으로 수행된 조사연구이다. 수집된 자료는 SPSS 프로그램을 이용하여 분석하였으며 주요결과는 다음과 같다. 환경 및 안전 사정에서 주거지에 위험시설이 있다고 응답한 사람은 전체의 46.2%인 67명 이었고, 이들 중 위험시설을 계단이라고 응답한 사람은 58.2%로 가장 높았고, 그 외 가스/전기 시설을 위험지역으로 응답하였다. 현 거주지의 위생상 문제가 있다고 응답한 사람은 전체의 28.2%인 41명 이었다. 이 중 현 거주지의 위생상 문제로는 집밖에 오염된 화장실이 있는 경우와 정돈되지 않고 오염된 주거환경이 22.0%로 가장 높았고, 벌레나 쥐가 있는 경우, 부적당한 음식보관, 불규칙한 쓰레기수거, 부적절한 하수도 시설도 문제점으로 지적되었다. 대상자들의 기능적 독립(FIM : Function Independence Measure)은 총 126점 중 평균점수는 74.52, 총 7점 중 평균평점은 4.14 이었다. 이 중 운동영역에서 가장 낮은 것은 계단오르기(3.01)와 목욕하기(3.16)였으며, 인지영역에서 가장 낮은 것은 사회활동(3.66)이었다. 질병으로 인한 장애영향은 총 91점 중 평균점수는 58.86점, 총 7점 중 평균평점은 4.52이었다. 질병으로 인한 장애영향을 가장 높게 받는 항목은 건강(5.61), 일(5.68), 활동적인 여가활동(5.56), 경제적 측면(5.45)이었다. 기능적 독립(FIM)과 질병으로 인한 장애영향과는 유의한 음의 상관관계가 있었다(r=-0.66, p=0.00).