Uranium-contaminated soil can be effectively decontaminated through acid leaching; however, this process process generates significant amounts of radioactive wastewater. Therefore, developing efficient methods to remove uranium from wastewater is essential to minimize radioactive waste generation. This study investigates the applicability of various precipitation methods for uranium removal from acidic wastewater produced during soil-washing processes. Three methods were evaluated: metal hydroxide (M–OHx) co-precipitation, uranium peroxide (UO4) precipitation, and uranium phosphate (KUO2PO4) precipitation. The M–OHx precipitation method removes uranium by precipitating excess metal ions in wastewater by adjusting the pH. This method is easy to use and has a high removal efficiency. The UO4 and KUO2PO4 precipitation methods involve adding reagents to precipitate uranium in the mineral phase. They enable selective uranium separation and further volume reduction. In the results, M–OHx and KUO2PO4 precipitation methods remove uranium to less than 1 mg∙L−1 within 2 h, demonstrating superior capabilities compared to UO4 precipitation. The optimal method is different depended on the management strategy for the recovered uranium. The M–OHx precipitation method was suitable for permanent disposal, whereas KUO2PO4 could be recycled. Based on these findings, guidelines for the effective treatment of wastewater containing uranium from the soil-washing process can be established.

This study developed and evaluated a non-coagulant dredged sediment treatment system as an eco-friendly river dredging and management technology. From 2014 to 2023, heavy rain damage in South Korea amounted to approximately 2.8 trillion KRW, with a sharp increase since 2020. River dredging has been recognized as a crucial countermeasure, and this study aimed to minimize the environmental impact of conventional dredging methods by introducing a non-coagulant treatment system. The developed system utilizes a remotely operated vehicle (ROV) to suction dredged sediment, which is then processed through sedimentation and filtration to separate solids and discharge treated water. Field tests were conducted in Seohwa Stream, Okcheongun, Chungcheongbuk-do. Results showed that the turbidity increase within the ROV operation area was minimal at 3.8%, and the suspended solids (SS) removal rate was 100%. Additionally, the system is akinetes discharge concentration was confirmed to be 0 cells g-1, demonstrating its effectiveness in water quality restoration. These findings confirm that the non-coagulant dredged sediment treatment system reduces environmental impact while ensuring efficient dredging and water quality enhancement. The proposed technology is expected to serve as a sustainable solution for river dredging and management.

이 연구의 목적은 염전에서 폐기되는 간수로 만든 담체의 비소 제거 특성을 연구한 것이다. 간수담체의 물리적 특성은 800 ~ 900℃에서 소성된 것을 사용하여 검토하였다. 비표면적과 흡수율은 각각 16.670 m2/g, 42.3%이었고 압축강도와 총 기공부피는 각각 28.3 kgf/cm2, 0.00818 cm2/g이었다. 간수담체의 화학적 조성은 SiO2가 55.3%이었고 특히, MgO가 19.2%로 매우 높은 농도로 존재하였다. 이런 결 과는 마그네슘 이온을 고농도로 포함하고 있는 간수의 영향을 받은 것으로 판단된다. 또한, X-Ray 회절 분석 결과, 간수담체는 Forsterite(Mg2SiO4)와 결정구조가 유사한 것으로 밝혀졌다. 간수담체는 제올라이트와 다양한 간수 용량으로 제조되었고 20% 간수로 만든 간수담체에서 비소 제거 효율이 최대화되었다. 또한, 수용액 중 간수담체의 용량이 40%일 때 90% 이상의 비소 제거 효율을 나타냈다. 간 수담체의 비소 제거 반응은 매우 빠르게 발생하였고 대부분의 비소 제거 반응이 수 시간 내에 끝났다. 회분식 실험을 통해서 간수담체의 비소 제거율에 미치는 pH 영향을 검토한 결과, 간수담체는 넓은 pH 범위(pH 5 ~ 10)에서도 높은 비소 제거 효율을 나타내었다.

In this paper, the commercial anion exchange resin (IRA900) was used to investigate the adsorption properties, comparing the anion selectivity of phosphate and sulfate in water. The phosphate removal efficiency was 29.6% less than sulfate in single condition, and significantly decreased from 44.8% to 3.47 in mixed conditions while sulfate removal efficiency remained unchanged, confirming a higher selectivity for sulfate over phosphate. In the pH effect, phosphate removal efficiency increased with increase of pH due to the increased HPO4 2- species. The total removal efficiency of phosphate and sulfate was obtained approximately 62% in mixed condition, regardless of solution pH, indicating that the total anion exchange capacity was not influenced in the pH. The values of qmL and bL derived from Langmuir isotherm equation were 11.5 and 8.10 times higher for sulfate than for phosphate in mixed conditions. In single condition, sulfate and phosphate reached to equilibrium at 6 and 3 h, respectively. In mixed condition, phosphate was desorbed by the sulfate after 1h and the time to equilibrium for sulfate was retarded to 6h. Furthermore, when comparing the separation factor (αP/S), increasing the initial concentration led to higher selectivity of phosphate.

Recently, the demand for shape memory alloys in the biomedical industry is increasing. Nitinol alloy, which accounts for most of the shape memory alloy market, occupies most of the biomedical field. Nitinol for biomaterials requires a clean surface without sub-micron surface integrity and surface defects in order to be used more safely in a living body. Among them, new technologies such as polishing using MR fluid are being studied, but there is a disadvantage in that it takes a long time for processing due to a low material removal rate. In this study, material removal studies were conducted for effective polishing, and excellent polishing properties of MR fluid were confirmed.

This study was performed to evaluate the pollutants removal characteristics of two types of RBFs(Riverbank filtration, Riverbed filtration) intake facilities installed in Nakdong River and in Hwang River respectively. The capacity of each RBF is 45,000 ㎥/d for riverbank filtration intake facility and 3,500 ㎥/d for riverbed filtration intake facility. According to data collected in the riverbank filtration site, removal rate of each pollutant was about BOD(Biochemical oxygen demand) 52%, TOC(Total organic carbon) 57%, SS(Suspended solids) 44%, Total coliforms 99% correspondingly. Furthermore, Microcystins(-LR,-YR,-RR) were not found in riverbank filtered water compared to surface water in Nakdong River. DOC(Dissolved organic carbon) and Humics which are precursors of disinfection byproduct were also reported to be removed about 59% for DOC, 65% for Humics. Based on data analysis in riverbed filtration site in Hwang River, removal rate of each contaminant reaches to BOD 33.3%, TOC 38.5%, SS 38.9%, DOC 22.2%, UV254 21.2%, Total coliforms 73.8% respectively. Additionally, microplastics were also inspected that there was no obvious removal rate in riverbed filtered water compared to surface water in Hwang River.

This study focused on using indirect filtration through riverbeds to produce high-quality drinking water. Data on water quality from a water intake facility(capacity 10,000 m3/day) and nearby rivers were collected over a three-year period. The average intake facility specifications were found to be a specific surface area of 58 balls/m2, a mean particle size of 24 mm, an inflow velocity of 2.2 cm/sec, and a burial depth of 5 m. The water quality improvement rate was assessed as grade Ia, surpassing the adjacent river’s water quality. Correlation analysis showed a weak correlation between opening ratio, Suspended Solid (SS), and Biochemical Oxygen Demand (BOD) compared to total coliforms and fecal coliforms. The correlation coefficient R value of SS was -0.614, BOD was –0.588, total coliforms -0.870, and fecal coliforms -0.958. The R value shows a negative value, which showed that the larger the opening rate, the lower the removal rate of water pollutants. The correlation coefficient R values according to the depth of burial were found to be BOD 0.914, SS-0.124, total coliforms 1.000, and fecal coliforms 0.866. The deeper the burial depth, the higher the removal rate of BOD and microbial groups.

The performance characteristics and usefulness of the duct-type gas removal system to which the catalytic combustion method was applied were investigated by experiment. Benzene, toluene, ethylbenzene, and xylene were selected for performance tests on gas detection and removal of the catalytic combustion system. Accelerated experiments were performed to evaluate the gas sensing performance, the adsorption performance of activated carbon, and the basic performance and durability of the catalytic combustion system. The amount of gas adsorption in the adsorption stage was changed according to the type of activated carbon, adsorption temperature and time. The adsorption amount increased with increasing temperature and particle size. BTEX gas removal rate was about 96%, and the performance of the module was maintained for more than 4,000 hours.

Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.

본 연구에서는 광화학 대기질 모델인 CMAQ을 활용해 화력발전소 배출량 제거에 따른 O3 농도의 변화 특성을 분석하였다. 하동 화력발전소를 대상으로 주변 지역의 O3 농도 변화에 대한 발전소 배출량의 영향을 조사하기 위해 하 동 화력발전소의 배출량 제거 전과 후의 CMAQ 수치 모의를 수행하였다. 수치 모의 결과 O3의 주요 전구 물질인 NOx (-18.87%)와 VOCs (-11.27%)의 농도가 감소한 반면에 O3 (25.24%)의 농도는 증가한 것으로 나타났다. 화력발전소 배출량 제거로 인한 NO와 O3 농도의 상대적인 변화를 비교해 본 결과 높은 음의 상관관계(R= -0.72)를 나타내는 것이 확인되었다. 이러한 결과는 O3의 농도 증가가 NO 농도 감소로 인한 O3의 적정 효과 완화로 설명 될 수 있음을 의미한 다. 해당 지역의 O3의 농도 증가가 NO의 농도 감소에 주로 영향을 받은 이유는 해당 지역이 VOC-limited (i.e., NOxsaturated) 지역이기 때문으로 분석되었다. 이러한 결과는 특정 지역의 O3의 농도가 단순히 배출량의 증감에 따라 비례하게 나타나지 않을 수 있다는 것을 암시한다. 따라서 화력발전소 배출량 저감 조치로 인한 대기 중 O3 농도 개선 효과를 정확히 예측 및 평가하기 위해서는 지역 별 O3의 생성 및 소멸 기작에 대한 심도 있는 이해가 필요하다.

대기오염물질 중 미세먼지는 심각한 사회적 환경문제로 인식되고 있다. 미세먼지의 원인 물질 중 하나인 질소산화물(NOx)은 석탄화력발전소의 연소공정에서 주로 발생하므로 효율적인 NOx 제거가 필요한 실정이다. 본 연구에서는 선택적 촉매 환원법(Selective Catalytic Reduction, SCR)을 이용한 NOx 제거에서 TiO2 광촉매의 NO 제거효율을 연구하였다. NO 제거효율을 평가하기 위해 발열제가 내장된 Al2O3 기판 표면에 TiO2 촉매와 인산염의 접착 바인더를 혼합하여 도포한 후 제조된 기판을 열처리하면서 실험을 수행하였다. 온도에 따른 촉매의 NO 제거효율을 평가하였고, 촉매의 물리화학적 특성을 위하여 XRD, SEM, TG-DTA, BET 분석을 수행하였다. NOx 제거 효율은 시간에 따른 온도변화(250℃∼500℃) 로 20분에서 제거효율은 58.7%∼65.9%이며, 30분에서 63.7%∼66.0%로 나타났다. 질소산화물 제거용 SCR로 사용되는 TiO2는 300℃가 제거효율이 가장 효율적인 것으로 판단된다.

In this study, various conditions and phenomena that occur in the process of removing odorous VOCs by using electrolyzed oxidant were examined. The formation of hypochlorous acid, which is an oxidant produced by electrolysis, was investigated and the properties of the oxidizing agent used to decompose toluene, xylene, and cyclohexane were investigated. As a result, it was found that the production rate and the final concentration of the oxidizing agent increased with the current density. It was found that the degree of removal varies depending on the property of each pollutant. Interestingly, in the batch experiments in which the pH of the produced oxidant was controlled, it was found that the degree of elimination varied depending on the pH of the substance. These results suggest that the difference in the concentration and distribution of hypochlorous acid (HOCl) and hypochlorite (OCl−) due to the pH change leads to the difference in oxidizing power on the oxidation characteristics of each substance. Styrene and terpineol showed better degradation characteristics than toluene and xylene in odorous VOC removal experiments by spraying electrolytic oxidant using a lab-scale continuous reactor. In conclusion, the removal of odorous VOCs by the electrolytic oxidant can have various applications in that it can oxidize pollutants of various spectra.

This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

본 연구는 콩 콤바인 수확 시 수확장애와 종실의 품위를 떨어뜨리는 잎과 줄기의 노화 지연에 관한 연구로 2015~2016년도 국립식량과학원 남부작물부(경남 밀양시 소재)의 시험포장에서 수행하였다. 시험품종은 대원콩과 풍산나물콩을 사용하였으며, 6월 9일에 고휴 2열로 휴폭 110 cm, 주간거리 40 cm, 1주 2본 재배하였고, 콩 꼬투리를 0~50%범위에 수준별로 제거하여 성숙기 생육특성과 잎과 줄기의 건물중에 대해서 조사하였다. 주요결과를 요약하면 다음과 같다. 1. 대원콩과 풍산나물콩 모두 종실비대시 콩 꼬투리 제거가 생육특성에 영향을 미치지는 않았지만, 제거 비율이 높아질수록 성숙기가 지연되었다. 2. 콩 꼬투리 제거 비율이 높아짐에 따라 종실 무게도 증가하였는데 꼬투리의 제거비율이 대원콩은 20%, 풍산나물콩은 30% 이상일 경우에는 차이가 없었다. 3. 꼬투리 제거비율이 높아질수록 잎과 줄기의 건물중이 증가하였는데, 이는 종자에 축적되어야 할 잉여 동화 산물이 잎과 줄기에 축적된 결과로 보여진다. 4. Sink/source 감소폭은 대원콩 20% 제거 시 0.18, 풍산나물콩 30% 제거 시 0.42로 이전 처리구에 비해 크게 감소하였기 때문에 잎과 줄기의 성숙이 불리할 것으로 판단된다.

It is necessary to develop a mobile water production system in order to provide stable water supply in case of disasters such as floods or earthquakes. In this study, we developed a modular mobile water production system capable of producing water for various uses such as domestic water and drinking water while improving applicability in various raw water sources. The water production system consists of three stages of filtration (sand filtration - activated carbon filtration - pressure filtration) to produce domestic water and an additional reverse osmosis process to produce drinking water. In laboratory and field experiments, the domestic water production system showed excellent treatment efficiency for particulate matter, but showed limitations in the treatment of dissolved substances such as dissolved organic matter. In addition, ultraviolet irradiation was considered as additional disinfection step, because it does not form precipitates of manganese oxides after disinfection. Reverse osmosis process was added to increase the removal efficiency of dissolved substances and the treated water satisfied drinking water quality standards. Fluorescence analysis of dissolved organic matter showed that the fulvic acid-like substances in raw water was successfully removed in the reverse osmosis process. The mobile water production system developed in this study is expected to be used not only in water supply in case of disaster, but also widely used in islands and rural area.

The objectives of this study were to evaluate the removal characteristics of total nitrogen, the influence factor of denitrification and the optimum operating condition in the pigment wastewater treatment using PAC-A/O process. The operating conditions of PAC-A/O process were mean BOD volumetric loading 0.86 kgBOD/m3/day, mean F/M ratio 0.072∼0.13 kgBOD/kgMLVSS/day and mean C/N ratio 3.47, respectively. The conditions of anoxic process in the field plant test were mean pH 8.3∼8.7 and mean temperature 34.1~44.0℃. The ORP bending point knee was eventually appeared in the ORP -107 mV and NO3 --N removal efficiency was increased according to the ORP decrease. In the ORP -107 mV below condition, the removal efficiency of T-N and NO3 --N was 92.3∼95.0% and 98.5∼99.7%. Denitrification rate was calculated to be 1.581∼1.791 mg NO3 --N/gMLSS/hr. The experimental results showed that the ORP control in the PAC-A/O process could be an effective method for treatment of pigment wastewater.

The water removal characteristics in a PEMFC trapezoidal gas channel are investigated with the volume of fluid (VOF) method. For the case of wall contact angle of 60 degree, liquid water attaches on the top wall and moves toward the exit. In contrast, liquid water moves along the channel side corner or GDL surface irregularly for the higher wall contact angles. The hydrophillic wall contact angle of 60 degrees provides more favorable diffusion of reactants to cathode reaction sites as the GDL surface water coverage ratio approaches zero even if the water flow rate increases.

In this study, we used activated carbon(AC) as a carbon source, along with zeolite, to prepare spherical carbons using sucrose, starch and phenolic resin(PR) as binder material. The physicochemical characteristics of the three samples(AZ4P, AZ6P and AZ8P) were examined by BET, XRD, SEM, EDX, H2S/NH3 gas adsorption, compressive strength and ignition test techniques. Through comparative analysis of the compressive strength and ignition test results the AZ8P sample was found to have the best hardness and the highest temperature resistance capacity. After activation, the AZ8P sample had the best H2S adsorption capacity, and AZ6P was the most suitable for the adsorption of ammonia.