• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.141-148
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• 2017

The oxidation ditch (OD) is one of the most widely used processes for treating municipal wastewater. However, the microbial communities in the OD systems have not been well characterized, and little information about the shift of bacterial community during the startup process of the OD systems is available. In this study, we investigated the bacterial community changes during the startup period (over 100 days) of a full-scale OD. The results showed that the bacterial community dramatically changed during the startup period. Similar to the activated sludge samples in other studies, Proteobacteria (accounting for 26.3%-48.4%) was the most dominant bacterial phylum in the OD system, but its relative abundance declined nearly 40% during the startup process. It was also found that Planctomycetes proliferated greatly (from 4.79% to 13.5%) and finally replaced Bacteroidetes as the second abundant phylum in the OD system. Specifically, some bacteria affiliated with genus Flavobacterium exhibited remarkable decreasing trends, whereas bacterial species belonging to the OD1 candidate division and Saprospiraceae family were found to increase during the startup process. Despite of the bacterial community shift, the organic matter, nitrogen, and phosphorus in the effluent were always in low concentrations, suggesting the functional redundancy of the bacterial community. Moreover, by comparing with the bacterial community in other municipal wastewater treatment bioreactors, some potentially novel bacterial species were found to be present in the OD system. Collectively, this study improved our understandings of the bacterial community structure and microbial ecology during the startup of a full-scale wastewater treatment bioreactor.

• 한국습지학회지
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• 제22권2호
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• pp.139-144
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• 2020

최근 고농도의 연계처리수를 인근 하수처리장으로 유입하고 있으나, 합리적이지 못한 연계처리 요금제도로 인해 지자체에서 하수처리 운영이 어려운 실정이며 이를 증명할 수 있는 근거나 데이터가 부족한 상황이다. 하지만, 국가 필수기반시설인 하수처리장은 일반적으로 예비타당성조사를 면제를 받기 때문에 경제성 평가를 실시한 사례가 전무하다. 따라서, 본 연구진은 선행연구를 통해 기존 연계처리 부과금의 단점을 보완할 수 있는 개선안을 제시하였고, 본 연구에서는 경제성분석을 실시하여 개선안을 적용하였을 때 기존 대비 얼마나 경제성이 개선될 수 있는지 비교평가를 하였다. 이를 위해 기존 환경시설의 예비타당성 평가 자료와 노후하수처리시설 현대화 진행 시 책정한 비용인자와 편익인자를 참고하였고, 연구진이 자체적으로 판단하였을 때 연계처리로 인해서 발생할 수 있는 편익 등을 고려하여 적용하였다. 연구결과 기존에는 B/C(Benefit/cost)값이 상당히 낮았으나, 연구진이 제안한 개선안을 적용하였을 경우 B/C값이 1에 가깝게 증가하는 것을 확인할 수 있었다. 따라서 본 연구진이 제안한 연계처리 부하에 따라 연계처리 부과금을 산정하는 방식은 매우 합리적이고 타당한 것으로 판단된다.

• 유기물자원화
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• 제16권2호
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• pp.57-65
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• 2008

일반적 중 저농도형 하수처리시설을 통해서는 처리가 힘든 고농도 유기성 폐수의 경우 재생에너지 생산이 가능한 혐기성 분해로 처리하는 것이 유리하다. 기존 호기성 처리에서 이미 그 실용성과 우수성이 입증된 E-PFR을 혐기성 처리에 적용하여 그 효용성과 재생에너지 생산 효율 증대 효과 등을 검증하고, 효율적인 재생에너지 생산을 위한 조건 등을 제시하기 위한 연구를 수행하였다. N 음식물쓰레기 처리시설에서 발생하는 탈리액을 대상으로 수행한 Pilot Plant 규모의 실험 연구에서 반응기의 구조적 특성으로 인해 혐기성 분해의 효율 향상 및 메탄가스 발생량이 증가함을 확인하였다. 이러한 처리 효율의 향상은 유체 이동관과 각단을 분리하는 격벽을 설치한 E-PFR의 구조적 특성에 기인한 원활한 혼합조건 형성과 스컴제어로 혐기성 처리에 있어서도 매우 이상적인 반응 조건을 형성시키기가 용이하였기 때문이다. E-PFR은 상향류식 폐수 유입과 각 단별로 분리된 다단형 처리로 인해 폐수 유입 구역에는 상대적으로 높은 MLSS가 유지될 수 있으므로 충격부하에 대한 내성이 강하고, 전체적으로 혐기성 최적 pH인 7.0~8.0 정도를 유지하여 상대적으로 높은 가스 발생량 및 메탄가스 함량을 유지하는 것이 가능하였다. 뿐만 아니라, 각 단별로 각기 다른 MLSS를 유지시키면서 SRT를 상대적으로 길게 유지함으로써 유기물 분해 및 가스 발생 효율을 증가시키는 효과가 있었다. 향후, 반응기의 구조적 개선과 발생가스를 이용한 교반 효과 개선 등을 통해 메탄가스 함량 70 % 수준의 안정적 혐기성 분해가 가능한 실증 플랜트 설계가 가능할 것으로 판단되며, 이를 통해 한층 향상된 재생에너지 획득 시스템 확보가 가능할 것이다.

• 상하수도학회지
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• 제28권2호
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제26권2호
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• pp.7-17
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• 2020

Purpose: The purpose of this study is to identify the operational status and current management of Sub-Health Centers in Limpio, Paraguay. Second, understanding the use of Sub-Health Centers and Perceptions of Sub-Health Centers in Limpio, Paraguay. Third, Providing policy implications for strengthening the Health Delivery System in Paraguay. Methods: The survey of the current status of sub-health centers in Limpio was conducted with observation and interview. Utilization of Sub-Health centers was analyzed in the 2018 Paraguay Community Health Survey. A face to face interview was conducted to complete a questionnaire and 831 samples were collected for the study. Results: In order to perform the normal function of the sub-health center, it will be necessary to allocate manpower that meets the standard. A common problem with sub-health centers in Limpio is that they have an environment vulnerable to rain. Currently, there are no health promotion and communicable disease management programs in sub-health center. Satisfaction of users about treatment, equipment, medicines and cleanleness of rooms. Implications: First, it is necessary to allocate human resources and organize spaces according to the standard. Second, there was a problem caused by moisture, and continuous maintenance and repair are required. Third, water and sewage related facilities must be safely improved to prevent contamination of groundwater. Forth, it is necessary to implement a program that fits the role of the sub-health center. Fifth, it is necessary to form a health delivery system considering the accessibility of residents. Finally, it is necessary to discuss the location of sub-health center considering travel time of Limpio residents.

• 상하수도학회지
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• 제8권2호
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• pp.1-11
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• 1994

This study was conducted to develop a new RBC process available for the effective removal of organic matters and nitrogen in sewage. The RBC process for the oxidation organic compounds and nitrification was designed to occur at the 1st-stage and next-stage RBC respectively. Then nitrified water was recycled to the denitrifying RBC located at the lower part of the 1st-stage RBC. Some results were summarized as follows. 1. The loading limitation was represented as $60g{\cdot}COD/gm^2/day$ in experiment of simultaneous removal of organic matter and nitrogen. The maxmum COD % removal was 85% at the load $35g{\cdot}COD/m^2/day$. 2. The $NO_3-N$ % removal was approximately 80% at the load $60g{\cdot}COD/m^2/day$ and the maximum $NO_3-N$ remaval rate was $3.9g{\cdot}COD/m^2/day$ and the overall C/N ratio of 11.0 as required to achive 80% of $NO_3-N$% removal. 3.$NO_3-N$ removal rate was rapidly decreased above the load $7g{\cdot}NH_4{^+}-N/m^2/day$ and the maximum $NO_3-N$ removal rate was $3.7g{\cdot}NO_3-N/m^2/day$. 4. Irrespective of the recycle ratio, the COD % removal at the system of 2-stage RBC unit was nearly constant as 89% while the maximum one in the 1st-stage unit was 77% in the case of 50% recycle. 5. The maximum COD % removal in the 3-stage RBC system was 93% while 1st-stage one being 80%, under the $NH_4{^+}-N$ load of $7.4g/m^2{\cdot}d$. Also maximum percentage of nitrification and denitrification was 69% and 41% respectively, under the same $NH_4{^+}-N$ load.

• 상하수도학회지
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• 제30권6호
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• pp.755-764
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• 2016

Pressure retarded osmosis (PRO) processes can be implemented on a number of water types, using different technologies and achieving various power outcomes. In this study, Sewage facility effluent was used for feed solution of PRO and synthetic NaCl water for draw solution. This study was conducted to investigate effect of water quality of pretreatment on power density and flux decline in PRO process. The results show that organic and particulate foulants have to be removed for more stable operation. Flourescence technique with EEM enables to investigate the chemical properties of aquatic organic matter by extracting spectral information. Humic/fulvic matters and soluble microbial by-products were analyzed as the most affecting factors on the PRO performance. As a result of analyzing the whole system based on the energy consumption of the unit process, specific energy consumption(SEC) of the applicable technology for PRO pre-treatment should be about $0.2kWh/m^3$ or less.

• 한국습지학회지
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• 제20권3호
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• pp.219-226
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• 2018

차집관로는 국유지가 많은 하천변에 매설되어 있어 파손이나 침입수/유입수(불명수, I/I) 의 유입으로 공공하수처리시설의 운영효율이 떨어지며, 하수관로 정비사업의 효율도 저하되는 것으로 나타났다. 본 연구는 하수관로 정비사업 효과의 감소원인에 가장 많은 영향을 미치는 차집관로를 대상으로 감소원인에 대한 분석을 하였다. 즉, 대상지역 3개소를 선정하여 차집관로의 현황조사(관로연장, 관경, 관종, 매설년도, 매설위치 등), 차집관로에 대한 차수(Pump 작업) 및 준설작업을 병행한 관로내부(CCTV)조사, 맨홀내부(육안)조사, 유량 및 수질조사 결과를 이용한 오염부하량 산정 등을 수행하였다. 합류지역은 동시 다측점 유량조사와 차집관로 유량 및 수질(BOD)조사, 오염부하량 비교 등을 수행하였으며, 차집관로 부실화에 따른 침입수/유입수 발생 현황 등 실태조사를 실시하였다. 연구결과, 하수관로정비 사업의 효과를 감소시키는 주요 원인은 차집관로의 노후화 및 미정비로 인해 공공 하수처리시설로 저농도 하수 및 불명수 유입되기 때문인 것으로 분석되었다.

• 한국습지학회지
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• 제18권4호
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• pp.448-455
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• 2016

환경부는 비점오염원 관리를 위해 시범사업으로 12개의 비점오염 저감시설을 경안천 유역에 설치하였으며, 2006년부터 모니터링이 시작되었다. 본 연구는 비점오염 저감시설의 오염부하량, 저감효율, 유지관리 활동 등의 장기간 수행된 모니터링 결과를 바탕으로 각 시설의 경제성을 평가하기 위해 수행되었으며, 생애주기비용(Lifecycle cost, LCC)을 분석하였다. 비점오염 저감시설의 유지관리는 시설경관을 향상시키기 위한 심미적 관리가 중점적으로 수행된 것으로 나타났으며, 저류형 시설(Retention Pond, RP)이 년간 8,483$, 침투형 시설(Infiltration System, IS)이 8,888$로 대부분 비슷한 비용이 발생한 것으로 분석되었다. LCC는 인공습지(Constructed Wetland, CW)가 가장 높은 것($418,324)으로 나타났으며, 반면에 식생형 시설(Vegetated System, VS)이 가장 낮은 것($210,418)으로 분석되었다. 본 연구에서 조사된 비점오염 저감시설의 LCC와 하수처리장 등 수질처리시설의 LCC를 비교한 결과 비점오염 저감시설이 낮은 것으로 나타났다. 한편, 처리용량 대비 생애주기비용이 높아질수록 TSS와 TN의 저감효율은 높아지는 것으로 나타났다. 이러한 연구결과는 비용효율적인 비점오염 저감시설을 설계하는데 유용하게 활용될 것으로 기대되며, 향후 LCC 모델의 기초자료에도 활용될 수 있을 것으로 판단된다.

• 한국환경과학회지
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• 제16권1호
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• pp.81-94
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• 2007

The purpose of this work is to investigate the water quality change characteristics of treated water in water distribution systems of Water Treatment Plants (WTPs) of Jeju City. For this, the raw water, treated water and tap water that did not pass (named as not pass-tap water) and passed through the water storage tank (named as pass-tap water) were sampled and analyzed monthly from September 2001 to August 2002, for four (W, S, B and O) WTPs except for D WTP (where treated water is not supplied continuously) among WTPs of Jeju City. The concentrations of $NO_3^-$ and $Cl^-$ of treated water in distribution systems changed little, but changed seasonally, which is considered to be based on the seasonal variation of the quality of raw water. The pH of treated water changed little in distribution systems for S WTP, but for the other WTPs, the pH of not pass-tap water was similar to that of treated water and the pH of pass-tap water was higher than that of treated water. The turbidity of treated water in distribution systems changed little except for W2 of W WTP and S4 and S5 of S WTP, where it was higher than that of each treated water. The residual chlorine concentrations between treated water and not pass-tap water changed little, but those between treated water and pass-tap water changed greatly, based on the its long residence time in water storage tank and so its reaction with organic matter, etc or its evaporation. The concentrations of TTHMs (total trihalomethanes) and $CHCl_3$ that induce cancers in water distribution systems of these WTPs, were much lower than their water quality criteria and those in other cities. The concentrations of TTHMs of treated water and not pass-tap water were similar, but concentrations of pass-tap water were 1.5 to 2.0 times higher than those of treated water and not pass-tap water, due to the reaction of residual chlorine and organic matter, etc, with the result of long residence time in water storage tank.