• 한국식품저장유통학회지
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• 제24권2호
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• pp.312-319
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• 2017

신선 농산물의 비가열 살균에 사용되는 살균소독제는 처리시간과 살균소독제의 농도에 비선형적인 감균효과를 나타낸다. 따라서 실제 사용에 있어서는 적정 농도와 적정 시간에 대한 고려가 매우 중요하다. 본 연구에서는 희석염산(6%, v/v)을 원료로 생성한 미산성 차아염소산수(slightly acidic electrolzyed water, SlAEW)($20{\pm}1^{\circ}C$에서의 유효염소 30 ppm, ORP $562{\pm}23mV$, pH 6.4)로 4종의 채소류(상추, 깻잎, 치콘 및 케일)에 대한 미생물 저감 특성을 분석하여 비가열 살균공정설계에 필요한 살균효과를 평가하였다. SlAEW에 30분간 3회 침지하면서 핵심인자인 유효염소와 미생물군수 및 잔류 미생물군수와의 관계를 분석하였다. 대부분의 총균수 감소는 1차 침지 초기 10분간 이루어졌으며 4종의 채소류에 생존하는 3 log CFU/g의 총균수가 침지를 통해 감소시킬 수 있는 한계값으로 판단되었다. 또한 SlAEW에 10분간 침지함으로써 감소시킬 수 있는 균수는 평균적으로 약 2 log CFU/g이었다. 초기 10분후의 감소된 유효염소는 상추, 깻잎, 치콘 및 케일에 대해 각각 2.2 ppm, 2.0 ppm, 1.7 ppm 및 2.5 ppm이었고 감소된 유효염소량의 약 50-80%가 초기 10분내에 감소되었다.

• 상하수도학회지
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• 제33권5호
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• pp.395-404
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• 2019

The point-of-use water dispenser systems are widely used because of convenience in handling and demand for high-quality drinking water. The application has been increased recently in the public places such as department stores, universities and the rest areas in express ways. Improvement of water qualities by the dispenser systems was compared with tap water in this study. The tap water is supplied to the dispenser as the influent of the dispenser system. The twelve dispensers in the public places were used. The five dispensers used reverse osmosis as the main filter and other dispensers used various filters such as ultrafiltration, nanofiltration, and alumina filter. The water quality indicators for sanitation safety, i.e., turbidity and total coliforms, were evaluated. Other water qualities such as pH, residual chlorine, heterotrophic plate count (HPC), and total cell counts were also analyzed. By the point-of-use water dispenser, the turbidity, residual chlorine and pH were decreased and the HPC and total cell counts were increased. The t-test results revealed that the HPC of the tap waters were not significantly different from the treated waters but the total cell counts of the two groups were significantly different. The low pH of the RO filter treatment was also significantly different from the tap waters. This study will contribute to understand the role of the point-of-use water dispenser in improving water quality and to identify key water quality for the proper maintenance of the dispenser systems.

• 한국물환경학회지
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• 제20권4호
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• pp.313-320
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• 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over $1,000m^3$ higher than those under $1,000m^3$. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over $1,000m^3$ was two times longer than it of those under $1,000m^3$(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

• Mycobiology
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• 제50권5호
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• pp.345-356
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• 2022

The fungal distribution, diversity, and load were analyzed in the geographically segregated island groundwater systems in Korea. A total of 79 fungal isolates were secured from seven islands and identified based on the internal transcribed spacer (ITS) sequences. They belonged to three phyla (Ascomycota, Basidiomycota, and Chlorophyta), five classes, sixteen orders, twenty-two families, and thirty-one genera. The dominant phylum was Ascomycota (91.1%), with most fungi belonging to the Cladosporium (21.5%), Aspergillus (15.2%), and Stachybotrys (8.9%) genera. Cladosporium showed higher dominance and diversity, being widely distributed throughout the geographically segregated groundwater systems. Based on the diversity indices, the genera richness (4.821) and diversity (2.550) were the highest in the groundwater system of the largest scale. As turbidity (0.064-0.462) increased, the overall fungal count increased and the residual chlorine (0.089-0.308) had low relevance compared with the total count and fungal diversity. Cladosporium showed normal mycelial growth in de-chlorinated sterilized samples. Overall, if turbidity increases under higher fungal diversity, bio-deterioration in groundwater-supplying facilities and public health problems could be intensified, regardless of chlorine treatment. In addition to fungal indicators and analyzing methods, physical hydrostatic treatment is necessary for monitoring and controlling fungal contamination.

• 한국물환경학회지
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• 제16권4호
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• pp.431-443
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• 2000

Water quality data from water treatment plants in Korea during 1994-1998 were investigated to find out the characteristics of their non compliance. The number of plants surveyed were approximately 600 and the number of samples were over 30,000. Ten parameters of water quality selected in this study and their non compliance % (inside parenthesis) were as follows: Heterotrophic plate count (0.14%), Total coliforms (0.08%), $NH_3$-N (0.29%), $NO_3$-N (0.14%), THMs (0.02%), Turbidity (0.11%), Residual chlorine (5.5%), $KMnO_4$ consumption (0.04%), Hardness (0.03%), pH (0.07%). These levels of non compliance were compared to those obtained from WIDB (Water Industry Database, 1996) of American Water Works Association. This study strongly supported that small water plants (<10,000 tons/day) were more vulnerable in meeting the regulation criteria of many water quality parameters such as Heterotrophic plate count. Total coliforms, $NO_3$-N, THMs, Turbidity, Residual chlorine, $KMnO_1$ consumption, Hardness and pH. The $NH_3$-N concentration was especially high in winter and its violation was frequently found in the specific areas such as the downstream of major rivers. The average THMs concentration was surprisingly low, indicating $13{\mu}g/L$ which is 43% of US. Accordingly, these characteristics must be reflected in establishing the effective management of water quality policy of drinking water in Korea.

• Journal of Yeungnam Medical Science
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• 제5권1호
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• pp.69-75
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• 1988

대구시내 6개구에서 각 2개소의 아파트와 각 1개소의 단독주책을 선정하여 총 18개소의 가정상수를 1987년 5월 12일에서 10월 15일 사이에 봄, 여름, 가을 3회에 걸쳐 채취하여 이화학적 및 미생물학적 수질검사를 시행하였다. pH치는 최저 6.80에서 최고 8.10으로 모두 정상범위였으며, 잔류염소치 0.2ppm미만인 경우가 아파트군 16.7%, 단독주택군 5.6%였다. 아질산성 질소양성은 아파트군에서만 2.8%로 나타났다. 일반세균수가 $m{\ell}$당 100개 이상인 경우는 아파트군 11.1%, 단독주택군 11.1%였고, 대장균군의 MPN이 1.8%이상인 경우가 아파트군 27.8%, 단독주택군 33.3%였다. 잔류염소치, 아질산성 질소, 일반세균수 및 대장균군 검사에서 4가지 음용기준에 부적당한 것은 아파트군에서만, 2.7%였고, 3가지 검사에서 부적당한 것이 아파트군 2.7% 단독주택군 5.6%, 2가지 검사에서 부적당한 것이 아파트군 8.3% 단독주택군 5.6%, 1가지 검사에서 부적당한 것이 아파트군 25.0% 단독주택군 22.2%였다. 이화학적 및 미생물학적 검사성적의 상호비교에서 잔류염소치와 일반세균수 사이에, 그리고 대장균균수와 일반세균수 사이에 연관성이 있었다. 아파트의 건립년수가 길수록 수질이 좋지 않은 것으로 관찰되었다.

• Journal of Preventive Medicine and Public Health
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• 제7권1호
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• pp.101-105
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• 1974

A study was carried out for the purpose of grasping the status of bacteriological contamination of the public wells in Iri city, during the period from 1 to 15 August, 1974. Coliform groups were detected by membrane filter method and physical conditions of the wells were checked. As results of this study, following conclusion were obtained. 1. The households which used the piped water occupied 70.8 per cent (11,907 households) out of total householdsir Iri city. 2. Temperature of the well water was 38 out of 50 samples (72.0%) with 12.1 to $16.0^{\circ}C$ and 9 wells with 10.1 to $12.0^{\circ}C$. 3. The pH values range of the well water was 6.0 to 7.9, 11 cases or 22,0 per cent less than 6.5 and 8 cases or 16.0 per cent more than 7.5. 4. The residual chlorine was found at 15 samples (30.0%) contained 0.1 to 0.5ppm, 9 samples (18.0%), 0.6 to 1.0 ppm after 24 houres of chlorination. 5. Coliform groups were found at 49 out of 50 samples (98.0%) before chlorination when 100ml well waters was tested by membrane filter technique and 15 wells(30.0%) were potable for drinking within 24 houres after chlorination. 6. Coliform groups positves were 23 out of 26 samples (88.5%) with no residual chlorine, 12 out of 16 samples (80.0%) with 0.1 to 0.5ppm and none out of 9 with 0.6 to 1.0ppm.

• 분석과학
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• 제17권1호
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• pp.69-81
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• 2004

한강과 낙동강에서 채취한 원수에 염소소독제인 hypochlorite를 $10{\mu}g/mL$의 농도로 투여한 후 1시간 ~ 14일까지 TOC (total organic carbon), 잔류염소량 및 14종의 염소소독부산물 생성율을 조사하였다. 그 결과 TOC 및 탁도는 큰 차이가 없었으며 잔류염소량은 한강에서 투여 후 1시간 경과 시 $6{\mu}g/mL$ 이상에서 14일째에 $1.23{\mu}g/mL$으로 감소한 반면 낙동강의 경우 3일 이후 거의 존재하지 않았다. 7일 후 발생한 총 소독부산물의 농도는 한강의 경우 101.3 ng/mL (789.6 nM)이며 이 중 THMs (trihalomethanes)가 68%로 가장 큰 비중을 차지하였다. 그 외에 HAAs (haloacetic acids, 19%), chloral hydrate(10%)가 검출되었으며, 낙동강의 경우 총 소독부산물의 농도가 98.4 ng/mL (678.6 nM)이며 이 중 HAAs가 57%로 가장 큰 비중을 차지하였다. 그 외에 THMs (34%), HANs (haloacetonitriles, 5%) 및 chloropicrin등 질소화합물의 농도가 증가하였다. 이는 낙동강의 경우 한강에 비해 상대적으로 많이 포함된 암모니아성 질소가 소독제인 염소와 반응하여 클로라민을 생성함으로써 염소에 의한 소독효과와 클로라민에 의한 소독효과를 함께 나타내기 때문인 것으로 사료되며 전체적인 소독부산물들의 생성비율 경향을 살펴보면 소독제의 종류에 따라 소독부산물의 생성패턴에 차이가 있으나 산성도가 큰 HAAs의 초기 생성농도가 높고 점차 THMs의 생성속도가 증가하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권8호
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• pp.1010-1020
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• 2014

Ballast water effluent treated by an electrolytic method contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for three marine pelagic organisms, i.e., diatom Skeletonema costatum, rotifer Brachionus plicatilis and fish Paralichthys olivaceus. The biological toxicity test revealed that S. costatum was the only organism that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 12.5%, 25.0% and 83.3%, respectively, at brackish water condition. In contrast, it showed insignificant toxicity at seawater condition. B. plicatilis and P. olivaceus also showed no toxicities to the effluent at the both salinity conditions. Meanwhile, chemical analysis revealed that the ballast water effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 20 DBPs including bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs) and chloropicrin. Based on ERA, the 20 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. Except monobromoacetic acid, the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other 19 DBPs did not exceed 1. Thus, our results of WET testing and ERA indicated that the ballast water effluent treated by electrolysis and subsequently neutralization was considered to have no adverse impacts on marine environment.

• 한국환경보건학회지
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• 제23권4호
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• pp.67-72
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• 1997

To evaluate the effectiveness of water treatment using nanofiltration, ultrafiltration, and microfiltration systems, tapwater contaminated by bacteria and nitrate nitrogen was filtered, and then the rates of removal for many kinds of contaminants were comp.ared and investigated. The rates of turbidity removal by these systems are around 80% all of them. However, nanofiltration system is the most effective as hardness removal is 80%, suspended solids 90%, total residual chlorine 90% and nitrate nitrogen 69%. Among nanofiltration, ultrafiltration and microfiltration systems, nanofiltration system is the most stable in flow rate of permeate. Comparing hollow and spiral type of ultrafiltration, microfiltration each, spiral type is more stable than hollow type owing to rinsing effect of brine. The values of pH in ultrafiltration and microfiltration systems are between 7, 0 and 7.5, and that of nanofiltration system is low to 6.2-7.0. The effectiveness of heterotrophic bacteria removal is the most excellent in the nanofiltration system.