• Parasites, Hosts and Diseases
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• 제57권1호
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• pp.49-53
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• 2019

Contaminated liver fluke egg in the environment has led to the high prevalence of human opisthorchiasis associated with cholangiocarcinoma in Southeast Asia. To find the effective lessening methods of Opisthorchis viverrini eggs in the contaminated environment, we investigated the temperature conditions for killing of these trematode eggs in vitro. Numerous O. viverrini eggs were obtained in the proximal part of uteri of adult worms from experimental hamsters. Mature eggs with miracidium were allocated by experimental groups (2 control: positive and negative and 4 treatment: 50, 60, 70, and $80^{\circ}C$) with 0.85% saline, and treated by the experimental plan. Eggs in each experimental groups were observed under the confocal microscope after stain with Propidium Iodide (PI) to evaluate the effect of temperatures. Eggs in 70 and $80^{\circ}C$ groups were all killed after over 10 min heated. Majority of eggs in $60^{\circ}C$ (10, 15, and 30 min heated), 70 and $80^{\circ}C$ (5 min heated) groups were inactivated. However in $50^{\circ}C$ group, below half of eggs were to be killed in all time lapse (10, 15 and 30 min). In order to prevent O. viverrini infection and cholangiocarcinoma, direct treatment of sewage by heating at 70 or $80^{\circ}C$ at least 10 min is essential. Therefore, treatment of O. viverrini eggs at a high temperature is a potential method for controlling egg contamination in sewage.

• Advances in environmental research
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• 제9권4호
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• pp.275-284
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• 2020

We provide the first study on the occurrence of microplastics in Dal lake, Kashmir, India. Microplastics act as catastrophe that trigger many environmental problems. The key origins of microplastics are larger plastics, which split into smaller plastics after UV light disintegration. There is relatively little work carried out on the existence of microplastics. The present work has been undertaken on the occurrence of microplastics at four pre-selected sites (surface water) in Dal lake, Kashmir. The samples were taken to the laboratory to dissolve organic matter by using H2O2 (6%). To speed up the organic digestion; the treated mixture was heated on a hot plate at 70℃. The mixture was then subjected to density separation. The supernatant obtained was observed under the microscope (10X) and measurements were taken. At site-I, the microplastics ranged from 2-3 mm, site-II 5-6 mm, site-III 3-4 mm, site-IV 4-5 mm in thickness, indicating the presence of microplastics in the lake. The presence of microplastics indicated that the lake has undergone an anthropogenic change over a period of time. Our research highlights the value of enhancing the quality of the drainage system and sewage disposal. This work can be helpful to recognize successful microplastic control management techniques and possible threats associated with the Dal lake. So far, no such data on the presence of microplastics in Kashmir lakes is available.

• 환경위생공학
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• 제10권1호
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• pp.98-105
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• 1995

In the treatment of wastewater or sewage plant sludge with high solid concentration, high rate digestion process in which heating and mixing occur at a time is mainly used, and in the case of wastewater containing solid matter below 1000mg/ℓ the recently developed AF or UASB is developed Recently and commonly utilized. But these processes have weakpoints such as clogging of packing media and need of long period of trial run after microorganism granulation. In this point of view, there are active researches on the ASBR( anaerobic sequence batch reaction ) that is capable of treating of organic matter with reactor that has no packing materials and controlling the inflow time, reaction time sedimentation time and outflow time by time control without loss of microorganisms. The objectives of this study are to evaluate the efficiency of ASBR process according to the reaction time, change of treated water quality and gas output rate in the treatment of wheat plant wastewater.

• 상하수도학회지
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• 제24권2호
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• pp.165-172
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• 2010

Treated sewage could enable growth by providing key nutrients or seeding the sediments with enterococci strains that can grow in the environment. This study is to test the hypothesis that the flux of bacteria into the water column is rate-limited by the transfer of bacteria across the sediment/water interface. Two conceptual models are derived for the transfer of bacteria to the water column from the sediment/water interface: convective diffusion of isolated bacteria and resuspension of particle-associated bacteria. The model predictions are directly tested together with field measurements of bacteria and sediment in an effluent-dominated stream where high concentrations of enterococci in this stream originate primarily from growth of the bacteria in stream sediments. The results reveal that high concentrations of enterococci in this stream are transported primarily by resuspension of particle-associated bacteria accumulated at the sediment/water interface, either in the form of bacterial aggregates or in the form of inorganic particles.

• 미생물학회지
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• 제10권4호
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• pp.175-190
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• 1972

This work was designed to illustrate physiological effects on the elimination of sulfur and its compounds in petroleum using sulfur-reducing bacteria. Deulfurizing bacteria were collected from sewage and soil at several areas in Soul and Ulsan, Korea. Seven supecies of sulfur-reducing microbes isolated were identified as : Pseudomonas marginata, Ps.effusa, Ps. putrefaciens, Ps.pseudcmcnelli, Ps. xanthochlora, Ps.bowlesiae, and Ps.aeruginosa. And some experiments were performed to define the growing characteristics of the Pseudomonads and the results obtained are as follows : 1) Shaking culture method was more effective for the growth of the cells than stagnant culture. 2) Beef peptone medium was better for the growth than other media. 3) Cuprous chloride of 50 ppm and cupper sulfate of 300 ppm treated, respectively, in the medium were effective for the growth. 4) Benzene of toluene of 5,000 ppm and petroleum ether of 50,000 ppm did not show remarkable inhibitory effects on the growth.

• 한국환경과학회지
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• 제5권4호
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• pp.513-524
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• 1996

Laboratory investigation was conducted to evaluat the mixing effects on organic removal efficiency to treat low-strength synthetic wastewater using modified anaerobic - filter reactor combining anaerobic filter and upflow anaerobic sludge blanket. Using the modified process the low-strength wastewater like municipal sewage could be treated with 85% T-COD removal efficiency at hydraulic retention time of 6 hours. At the constant organic loading of 0.5 kg COD/m 3-day, the organic removal efficiency and effluent COD concentration are increased as influent COD concentration increased from 125 mg/l to 500 mg/l. Mixing effects on organic removal efficiency are evident and optimum mixing speed is found as 50RPM. Placing the granular sludge and media on which slime layer was pre-formed into the reactor seemed to be very effective In achieving short start-up period. Therefore, the steady state was achived after 4 weeks and 1 week based on T-COD and S-COD, respectively.

• 환경위생공학
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• 제15권3호
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• pp.57-61
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• 2000

Stapylococcus auricularis was used for the simultaneous removal of phosphorus and Total Organic Carbon(TOC) in the wastewater from sewage and various industries. In this study, the characteristics of phosphorus removal was investigated with initial ratio of TOC phosphorus in the synthetic wastewater. When the synthetic wastewater containing 15mg/L of phosphorus was treated under anaerobic and conditions, phosphorus was removed completely within 6 hours of operation. And when the initial ratio of TOC to phosphorus was 30, as high as 10 times the removal rate of phosphorus by Acinetobacter calcoaceticus was achieved. These results implied that a long adaptation time, one of the chief problems in biological phosphorus removal process was overcome.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.984-993
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• 1993

land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and groundwater. A rainfall simulator was used to investigated the effects of freshly applied sludge on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three run sequence was used to simulate different initial moisture conditions. Runoff, sediment and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally -tilled plots and surface applied at no-till plots, at rates of 0, 75, 150 kg-N/ha. No-till practices greatly reduced runoff, sediment , and nutrient losses form the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally-tilled plots. This effect was more pronounced during the third rain torm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions.

• 상하수도학회지
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• 제7권1호
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• pp.13-19
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• 1993

Anaerobic Digestion of thickened septage was investigated in this study. Thickening could reduce the volume of septage to be treated to about 40% with 12hr HRT. The VS and BOD removal efficiencies were respectively 28 to 45%, and 75% when digested the thickened septage with 30 day HRT Or $1.4kgVS/m^3/d$. The BOD removal efficiency could be increased to about 90% with subsequent settling tank with about 6 hours HRT. The gas production rate was 0.22 to $0.35m^3gas/kgVSadd$($0.75m^3gas/kgVSrm$), or $1.32m^3gas/kgBOD_{rm}$. In addition, the supernatant of thickener could be returned to the aeration tank treating domestic sewage. In this case, a BOD loading rate of 0.5 to $0.7kgBOD/m^3/d$ or 0.5kgBOD/kgMLVSS/d was proposed for 80% BOD reduction.

• ALGAE
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• 제23권3호
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• pp.219-230
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• 2008

The structure of phytoplankton community was studied for one year round at 6 stations in the Beopsu Marsh, Haman-gun, Gyeongsangnam-do, Korea. One hundred seventy-eight taxa (69 taxa belonging to Chlorophyta, 55 taxa to Bacillariophyta, 33 taxa to Cyanophyta, 15 taxa to Euglenophyta, 2 taxa to Rhodophyta, 2 taxa to Dinophyta and 1 taxon to Xanthophyta) were observed. Phytoplankton bloom occurred at the staions 2, 3 and 4 where waters were polluted by sewage and treated water of purification plants from the vicinity. The species diversity index of phytoplankton was the lowest (0.66) in November at the station 3, which the station showed the most eutrophic water due to the diverse pollutants from surroundings of the marsh. For the whole seasons, Fragilaria sp. and Euglena sp. appeared in pollutant water at the station 3, while Cyclotella sp. and Pinnularia sp. inhabited in relatively clean water at the station 5. To reserve the natural treasure, the wetland should be more specially managed by a local governing institution.