To improve the safety of tap water, a study was conducted on the introduction of sanitation safety certification system for water treatment plants(WTPs). In order to produce and supply safe tap, the inflow of pollutants should be blocked as much as possible during the tap water production process, and contaminated materials should be removed or inactivated to a safe level in the WTPs. In order to block the inflow of pollutants in WTPs, it is necessary to strengthen the sanitation management such as installation of facilities for preventing inflow and habitat of larvae, and to remove or inactivate pollutants in the tap water production process, strengthening the safety management such as enhanced turbidity management is needed. Sanitation and safety management in the WTPs can be significantly improved by introducing certification system of WTPs. This will induce continuous improvement in water purification plants with insufficient sanitation and safety management, and provide incentives for WTPs with good sanitation and safety management. In addition, when the WTPs sanitation and safety certification system is established, it is desirable to expand the proposed system from WTPs to the entire process of tap water production and supply.

A Gravity-driven membrane (GDM) system is one of the promising solutions for household drinking water treatment in the developing countries. In this study, the GDM system was tested for optimizing manual cleaning protocols using three different feed water solutions. Two types of manual cleaning were performed to delay the permeability decrease, cleaning between batches and long-term cleaning. The optimized cleaning between batches protocol was 3 twisting and 10 vertical shaking. And the optimized long-term cleaning protocol was 70 vertical shaking for both the middle region of the module and near the header part. These cleaning protocols allowed the system to produce sufficient water to meet the daily minimum water requirements for a 5-person family, even for using the wastewater influent. The system produced Escherichia coli free water.

수처리에 있어 막여과 기술은 안전한 처리수질의 보장, 시스템의 집약화 및 자동화 등의 장점으로 인해 활발히 도입되고 있다. 하지만 핵심 기자재인 막 모듈의 설계나 전체 정수처리 공정의 안정성 부분에 대해서는 아직 기술개발의 여지가 남아 있다. 본 연구에서는 막여과 공정의 연속 운전에 있어서 막오염을 완화시키기 위한 목적으로 수행하는 물리적인 역세척의 효율 향상과 더불어 이 때 발생하는 역세배출수를 막 모듈 외부로 원활히 배출할 수 있도록 한 가압식 막여과 기술과, 이 때 발생한 가압식 막여과 배출수를 이중 구조로 구획된 침지 막조 이용하여 원활히 처리할 수 있는 침지식 막여과 기술을 결합하여 기존 기술에 비해 고회수율의 달성은 물론, 집약적이고 실용적인 2단 막여과 정수처리 시스템을 개발하고자 하였다.

Modeling of forward osmosis (FO) membrane system is significantly affected by various factors such as membrane properties of materials (A, B), structure parameter (S), concentration polarization (CP), fouling, spacer design. etc. In this study, FO performance of a plate and frame type membrane is investigated via a numerical simulation based on mass conservation theorem and finite element method (FEM). To evaluate the FO membrane performance, permeate flux and recovery rate are simulated according to membrane orientation, flow direction of feed and draw solutions, flow rates, membrane structure parameter (S), and design of spacers. The modeling results can help to expand insights into FO separation characteristics and to suggest further strategy for FO process development.

Various treatment system for residuals have applied to save water resources, but most of them were not be satisfied with legal standard consistently. In this study, submerged membrane treatment system was operated to treat water treatment plant residuals and operation parameters was evaluated. Result of this experiment, high concentration organic matters contributed to high increase Transmembrane pressure(TMP) of membrane system(from 0.05 bar to 0.35 bar). And backwash process was effective to stabilize membrane system operation. After Cleaning-In-Place(CIP), permeability was recovered about 100 % from first operation condition. Inorganic matters (Fe, Mn, Al, Ca, Mg) were not effective membrane filtration performance. The quality of residual treatment was satisfied with drinking water quality standard and a treated water from that system was suitable for water reuse.

The hydrofoil-tip mixer can be used to create the desired material by mixing the two materials in various industries, especially in the waste water and sewage water treatment. The purpose of this study is to clarify flow characteristics induced by 3 types impellers in a mixing tank by CFD. In this study, flat plate, hydrofoil and hydrofoil-tip type impellers are used and the rotating speeds of impellers are 25, 35, 45 rpm. The results in present study show that hydrofoil-tip type is the most proper impeller for mixing in the waster water treatment tank and reducing required power of rotating impeller. This results can be used for the design of the mixing tank in the waste water treatment system.

본 연구에서 처리수를 이용한 주기적인 역세척은 춘천시 공지천의 관형 세라믹 한외여과막에 의한 고도정수처리 시스템에서 막오염을 저감하고 투과선속을 향상시키고자 수행되었다. 일정한 역세척 시간(BT) 15초에서 여과시간 즉, 물 역세척 주기(FT) 2분이 가장 높은 무차원 투과선속(초기 투과선속에 대한 투과선속)과 가장 낮은 막오염 저항값을 보였다. 또한, FT 10분으로 고정한 BT 영향의 결과에서 BT 20초가 가장 낮은 막오염 저항과 가장 높은 무차원 투과선속을 나타내어, 가장 많은 총여과부피 107.3 L를 얻을 수 있었다. 결론적으로 공지천의 정수처리에서 FT 10분과 BT 20초가 최적조건으로 관형 알루미나 정밀여과의 선행 연구결과와 정확히 일치하였다. 한편 관형 세라믹 한외여과 시스템에 의한 오염물질 평균제거율은 탁도 97.0%, 망간법에 의한 COD 32.1%, 암모니아성 질소 28.8%, 총인 54.4%로 나타났다.

본 연구에서 처리수를 이용한 주기적인 역세척은 세라믹 정밀여과에 의한 고도정수처리 시스템에서 막오염을 저감하고 투과선속을 향상시키고자 수행되었으며, 물 역세척 주기(FT) 및 시간(BT)의 영향과 최적 운전조건을 규명하고자 하였다. FT의 영향을 알아보기 위해 일정한 BT 3초에서 FT를 30∼120초로 변화시켰고, BT 영향 실험에서 일정한 FT 120초에서 BT를 3∼12초로 변화시켰다. 그리고 다른 운전변수인 막간압력차는 1.52 bar, 물 역세척 압력 0.98 bar, 유입유량 0.5 L/min, 공급액의 온도 20℃로 일정하게 유지하였다. 그 결과, 일정한 BT 3초에서 본 실험 범위의 최적 FT는 30초로, 이것은 빈번한 역세척이 막오염의 저감에 더 효과적임을 의미한다. 그러나 너무 짧은 BT로 인하여 FT의 영향은 크지 않았다. 한편, 일정한 FT 120초에서 BT가 증가함에 따라 막오염에 의한 저항(Rf)은 감소하고 투과선속(J)과 무차원화한 투과선속 (J/Jo)은 증가하는 경향을 나타내어, 최대 BT인 12초에서 가장 많은 총여과부피(VT)를 얻을 수 있었다.

본 연구에서는 4종류의 관형 세라믹 정밀 및 한외여과막(탄소 재질)으로 제지공장의 방류수를 물로 주기적 역세척하면서 여과하였을 때, 최적 역세척 시간을 규명하였다. 각 분리막에 대상으로 물 역세척 시간의 영향을 살펴 본 결과, 분리막의 기공이 클수록 길게 역세척 하는 것이 가장 많은 총여과부피, 즉 처리수의 회수 효율이 높기 때문에 가장 효과적이라 할 수 있다. 한편, 180분 동안 여과하면서 초기투과선속에 대한 투과선속의 변화를 살펴본 결과, 정상운전시간이 길수록 막오염이 많이 진행된 상태이므로 역세척 시간을 길게 해주여야만 막오염을 억제하여 높은 투과선속을 유지할 수 있다는 것을 알 수 있었다. 또한, 막오염의 저항 변화 추이를 관찰하여 최적 물역세척 시간을 규명해 보아도, 투과선속의 변화로부터 얻은 최적 역세척 시간과 거의 동일한 결과를 얻을 수 있었다.

To comparison the surface treatment methods of stone board materials, the results of Dorry's abrasive test were 23.4 for water-jet system and 18.9 for flame-burner system. Therefore abrasive hardness, the stone board materials by the water-jet system was greater than one by flame-jet system. As a result of Shore's hardness test, the stone board materials by water-jet system was twice greater than one by flame-jet system. Authors carried out microscopic observation to survey a defection of the composition minerals for two methods, but all of the both methods have not founded a defection. Therefore, the stone board materials by water-jet system was greater durability than one by flame-jet for the surface treatment methods.

기존의 정수처리 공정인 응집 침전 과정을 대체하여 분리막을 이용한 상수처리 시스템의 개발을 목적으로한다. 따라서 4가지 형태의 정수처리 공정과 분리막의 분획 분자량을 변화시켰을 때 막 투과수의 변화와 안정적이며 높은 투과수를 얻기 위해 필요한 운전 조건의 최적화를 실험하였다 실험결과 한외여과막이 정밀여과막보다 막 투과수 감소경향이 완만했으며 초기 투과수 회복율은 더 높았다. 수질 분석의 결과 한회여과막이 정밀 여과막보다 우수하였지만 전처리에 의한 차이는 나지 않았다. 운전 조건에 따른 flux 는 온도, 선속도가 높을수록 압력이 낮을수록 flux 감소율이 적은 경향을 나타내었다.

Economical radioactive soil treatment technology is essential to safely and efficiently treat of high-concentration radioactive areas and contaminated sites during operation of nuclear power plants at home and abroad. This study is to determine the performance of BERAD (Beautiful Environmental construction’s RAdioactive soil Decontamination system) before applying magnetic nanoparticles and adsorbents developed by the KAERI (Korea Atomic Energy Research Institute) which will be used in the national funded project to a large-capacity radioactive soil decontamination system. BERAD uses Soil Washing Process by US EPA (402-R-007-004 (2007)) and can decontaminate 0.5 tons of radioactive soil per hour through water washing and/or chemical washing with particle size separation. When contaminated soil is input to BERAD, the soil is selected and washed, and after going through a rinse stage and particle size separation stage, it discharges decontaminated soil separated by sludge of less than 0.075 mm. In this experiment, the concentrations of four general isotopes (A, B, C, and D which are important radioisotopes when soil is contaminated by them.) were analyzed by using ICP-MS to compare before and after decontamination by BERAD. Since BERAD is the commercial-scale pilot system that decontaminates relatively large amount of soil, so it is difficult to test using radioactive isotopes. So important general elements such as A, B, C, and D in soil were analyzed. In the study, BERAD decontaminated soil by using water washing. And the particle size of soil was divided into a total of six particle size sections with five sieves: 4 mm, 2 mm, 0.850 mm, 0.212 mm, and 0.075 mm. Concentrations of A, B, C, and D in the soil particles larger than 4 mm are almost the lowest regardless of before and after decontamination by BERAD. For soil particles less than 4 mm, the concentrations of C and D decreased constantly after BERAD decontamination. On the other hand, the decontamination efficiency of A and B decreased as the soil particle became smaller, but the concentrations of A and B increased for the soil particle below 0.075 mm. As a result, decontamination efficiency of one cycle using BERAD for all nuclides in soil particles between 4 mm and 0.075 mm is about 45% to 65 %.