본 연구에서는 천연 항균제인 광귤 추출물의 항균 활성 과 항균 메커니즘을 조사해 즉석섭취식품인 샐러드에서 Salmonella Typhimurium을 제어하기 위한 세척수로써 적용 가능성을 평가하였다. 액체배지희석법으로 S. Typhimurium 에 대한 광귤 추출물의 최소 억제 농도(MIC)를 구했다. 그런 다음 다양한 농도(1/16 MIC-2 MIC)에 해당하는 광 귤 추출물에 S. Typhimurium을 접종하고 성장곡선을 분석 해 대조군과 성장값을 비교하여 항균 활성을 확인하였다. 광귤 추출물을 처리한 후, S. Typhimurium의 세포 내 활 성산소종 수준과 막 전위 및 손상도의 변화, 핵산 누출량 을 측정하여 광귤 추출물의 항균 메커니즘을 확인하였다. 최종적으로 S. Typhimurium을 인위적으로 접종한 샐러드 에 다양한 농도의 광귤 추출물을 다양한 시간 동안 침지 방법으로 항균 처리하여 저감화 효과를 확인했다. S. Typhimurium에 대한 광귤 추출물의 MIC는 195.313 mg/ L으로, 1 MIC와 2 MIC의 광귤 추출물은 S. Typhimurium 의 성장을 완전히 억제하였다. 광귤 추출물의 처리농도가 높아질수록, 세포 내 ROS 수준과 막 전위, 막 손상도 그 리고 핵산 방출량은 증가하였다. 마지막으로, 세척수인 광 귤 추출물의 농도가 높고 처리 시간이 길수록 샐러드의 S. Typhimurium의 수가 감소하였다. 따라서 광귤 추출물은 S. Typhimurium를 효과적으로 제어할 수 있음을 입증했다. 광귤 추출물은 차아염소산나트륨과 비교하였을 때 효과적 인 항균 활성을 보이며 안전한 샐러드 세척수로 사용될 수 있다. 이는 샐러드와 같은 식품에서 광귤 추출물이 식 중독 발생을 미연에 방지하는데 기여할 수 있음을 시사한다.

해수담수화는 지구 수자원의 97%에 해당하는 해수를 활용하기 때문에 물부족 문제를 해결할 지속가능한 대안으로 평가받고 있다. 최근에는 증발식 해수담수화 대비 에너지 소모가 낮은 분리막 방식이 널리 적용되고 있으며, 에너지 소모는 3-4 kWh/m3 정도이다. 해수담수화 플랜트 소요비용 중 운영비용이 약 35~65%를 차지하므로 해수담수화 기술의 확대 적용을 위해서는 비용 절감형 운영 기술 개발이 필수적이다. 이에 K-water에서는 ‘중동지역 맞춤형 저에너지 해수담수화플랜트 기술개발’ 과제 참여를 통해 저에너지⋅고효율 해수담수화 운영 기술을 개발하고 있으며, UAE에 구축될 1,000m3/d 규모 플랜트에 적용할 계획이다. 본 기술 적용을 통해 해수담수플랜트 연간 운영비용 증가율을 5% 이내로 유지하는 것을 목표로 한다.

막여과 정수장에 고농도 망간이 유입될 경우 심각한 막오염을 유발할 수 있어 망간에 대한 제어가 필요하다. 최근 수처리제로 등록된 NaMnO4의 경우 짧은 반응시간에 망간 제거가 가능하여 정수장 적용이 유리할 것으로 기대되고 있다. 본 연구에서는 NaMnO4 주입에 따른 망간 제거 성능과 막의 여과유속에 미치는 영향을 평가하였다. 유입망간농도 대비 NaMnO4 주입 조건을 평가한 결과반응시간 5분 이내 1배, 1.5배 조건에서 약 90% 이상의 망간 제거 효율을 나타내었으며 0.5배, 2배 조건에서는 제거효율이 감소되었다. 또한, NaMnO4 주입조건과 미주입 조건에 대한 여과유속을 평가한 결과 미주입 조건과 비교하여 주입조건에서의 막오염이 저감되어 미주입 조건과 비교하여 유과유속이 높게 유지되었다.

This study was evaluated the applicability of the membrane filtration process (Micro Filtration (MF), nanofiltration membranes (NF), reverse osmosis (RO)) on the major radioactive substances, iodine (I-) and cesium (Cs+) using membranes produced in Korea and domestic raw water. Iodine (I-) or cesium (Cs+) in the microfiltration membrane (MF) process could not be expected removal efficiency by eliminating marginally at the combined state with colloidal and turbidity material. At the domestic raw water (lake water, turbidity 1.2 NTU, DOC 1.3 mg/L) conditions, nanofiltration membrane (NF) and reverse osmosis (RO) showed a high removal rate of about 88 ~ 99% for iodine (I-) and cesium (Cs+) and likely to be an alternative process for the removal of radioactive material.

Algal problem in drinking water treatment is being gradually increased by causing deterioration of water supplies therefore, especially taste and odor compounds such as geosmin and 2-MIB occur mainly aesthetic problem by its unpleasant effects resulting in the subsequent onset of complaints from drinking water consumer. Recently, geosmin and 2-MIB are detected frequently at abnormally high concentration level. However, conventional water treatment without advanced water treatment processes such as adsorption and oxidation process, cannot remove these two compounds efficiently. Moreover, it is known that the advanced treatment processes i.e. adsorption and oxidation have also several limits to the removal of geosmin and 2-MIB. Therefore, the purpose of this study was not only to evaluate full scale nanofiltration membrane system with 300 m3/ day of permeate capacity and 90% of recovery on the removal of geosmin and 2-MIB in spiked natural raw water sources at high feed concentration with a range of approximately 500 to 2,500 ng/L, but also to observe rejection property of the compounds within multi stage NF membrane system. Rejection rate of geosmin and 2-MIB by NF membrane process was 96% that is 4% of passage regardless of the feed water concentration which indicates NF membrane system with an operational values suggested in this research can be employed in drinking water treatment plant to control geosmin and 2-MIB of high concentration. But, according to results of regression analysis in this study it is recommended that feed water concentration of geosmin and 2-MIB would not exceed 220 and 300 ng/L respectively which is not to be perceived in drinking tap water. Also it suggests that the removal rate might be depended on an operating conditions such as feed water characteristics and membrane flux. When each stage of NF membrane system was evaluated relatively higher removal rate was observed at the conditions that is lower flux, higher DOC and TDS, i.e., 2nd stage NF membrane systems, possibly due to an interaction mechanisms between compounds and cake layer on the membrane surfaces.

This study was carried out to investigate efficacy of aerosol sanitizer with natural antimicrobial and organic acids against Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes. The artificially inoculated pathogens on stainless steel coupon were treated with grapefruit seed extract (GFE), acetic acid,citric acid and lactic acid in model cabinet for 5 min. The number of three foodborne pathogens with individual treatment was reduced by 0.34-3.77 log units, treatment with GEF + organic acid was reduced by 1.72-3.89 log units and treatment with GEF + organic acid + alcohol was reduced by 1.46-5.05 log units. By treatment with GEF + lactic acid + alcohol in scale-up model system for 10 min. Populations of E. coli O157:H7, S. Typhimurium and L. monocytogenes were reduced by 3.42, 2.72 and 2.30 log units from the untreated control respectively. From the above result,aerosol sanitizer with natural antimicrobial agents and organic acid can be used as an environmental sanitation method with satisfying the consumer demand on safe food.

The plate tectonics is the theory which can systematically interpret various kinds of changes of crusts on the earth surfaces. If the concepts of this theory is taken a triangular position and systematically played up at the curricula of the earth science in the high school, this theory may be able to become the most adequate subject for students to interest in the earth science. The aim of this study is the making out the expanded model of the unit of plate tectonics for the purpose of the more effective teaching-learning of the plate tectonics and the improvement of curricula on the plate tectonics in the high school.

This study was conducted to evaluate the feasibility of ammonia removal by zeolite adsorption in drinking water treatment. In generally, drinking water treatment process is conducted coagulation/flocculation, sedimentation, sand filtration and disinfection. We tested feasibility with two method, one is powdered zeolite dosing to coagulation tank and the other is to substitute granular zeolite for sand of sand filter. In powdered zeolite test, raw water is used tap water with putting of 2mg/l of NH4+-N. Filtration of granular zeolite was conducted with 80cm of effective column high and 120m/d of flow rate. At above 100mg/l of zeolite dosage, ammonia concentration was decreased below 0.5mg/l of NH4+-N in powdered zeolite test. But, turbidity was increased to 30NTU by powdered zeolite dosage. That turbidity was scarcely decreased in generally coagulant using condition in drinking water treatment. In granular zeolite test, ammonia was not detected in treated water until 8 days. This result suggest that using of granular zeolite in sand filter could be removal ammonia in winter. But we need regeneration at zeolite filtration for ammonia removal. So, it is to make clear that zeolite regeneration ability was compared KCl with NaCl. The result reveal that KCl was more excellent than NaCl. Optimum regeneration concentration of KCl was revealed 100 mM. Regeneration efficient was not increased at pH range 10～12.5