This study develops a model to determine the input rate of the chemical for coagulation and flocculation process (i.e. coagulant) at industrial water treatment plant, based on real-world data. To detect outliers among the collected data, a two-phase algorithm with standardization transformation and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) is applied. In addition, both of the missing data and outliers are revised with linear interpolation. To determine the coagulant rate, various kinds of machine learning models are tested as well as linear regression. Among them, the random forest model with min-max scaled data provides the best performance, whose MSE, MAPE, R2 and CVRMSE are 1.136, 0.111, 0.912, and 18.704, respectively. This study demonstrates the practical applicability of machine learning based chemical input decision model, which can lead to a smart management and response systems for clean and safe water treatment plant.

There are two primary sludge drying methods such as the direct heating microwave method and the indirect heating steam one. In this study, the drying treatment facility at sewage treatment plant A applied both of these drying methods. The research aimed to investigate the optimal operation approach for the drying facility, considering the input sludge and the moisture content data after the drying process. Moisture content and removal rate data were executed at the research facility from January 2016 to December 2018. First, the microwave, a direct heating drying method, performed intensive drying only on the outer surface of the sludge by directly applying heat to the sludge using far infrared rays, so effective sludge drying was not achieved. On the other hand, the steam method of the indirect heating method used steam from a gas boiler to maximize the utilization of the heat transfer area and reduce energy of the dryer, resulting in an effective sludge drying efficiency. The sludge moisture content brought into the sludge drying facility was about 80%, but the moisture content of the sludge that went through the drying facility was less than 10% of the design standard. Therefore, the steam method of the indirect heating method is more effective than the microwave method of the previous direct heating method and is more effective for maintenance It has proven that it is an efficient method of operating construction facilities.

The purpose of this study is to analyze the correlation between ecotoxicity and water quality items using Daphnia magna in public sewage treatment plant process and to obtain operational data to control ecotoxicity through research on removal efficiency. The average value of ecotoxicity was 1.39 TU in the influent, 1.50 TU in the grit chamber, and 0.84 TU in the primary settling tank and it was found that most organic matters, nitrogen, and phosphorus were removed through biological treatment in the bioreactor. Using Pearson’s correlation analysis, the positive correlation was confirmed in the order of ecotoxicity and water quality items TOC, BOD, T-N, NH3-N, SS, EC, and Cu. As a result of conducting a multilinear regression analysis with items representing positive correlation as independent variables, the regression model was found to be statistically significant, and the explanatory power of the regression model was about 81.6%. TOC was found to have a significant effect on ecotoxicity with B=0.009 (p<.001) and Cu with B=16.670 (p<.001), and since the B sign is positive (+), an increase of 1 in TOC increases the value of ecotoxicity by 0.009 and an increase in Cu by 1 increases the value of ecotoxicity by 16.670. TOC (β=0.789, p<.001) and Cu (β=0.209, p<.001) were found to have a significant positive effect on ecotoxicity. TOC and Cu have a great effect on ecotoxicity in the sewage treatment plant process, and it is judged that TOC and Cu should be considered preferentially and controlled in order to efficiently control ecotoxicity.

Domestic nuclear power plants can affect the environment if multiple devices are operated on one site and even a trace amount of pollutants that may affect the environment after power generation are simultaneously discharged. Therefore, not only radioactive substances but also ionic substances such as boron should be discharged as minimally as possible. We adopted pilot CDI and SD-ELIX sytem to separating and concenrating of boron containing nulcear power plant discharge water. The boron concentration of the initial inflow water tended to decrease over time. The water quality of concentrated water also reached its peak until the initial 60 minutes, but tended to decrease in line with the decrease in the inflow water concentration. The boron removal rate was in the range of 85 to 99% with respect to the initial boron concentration of 15 to 25 mg/L. On the other hand, performance degradation due to the use of electrochemical modules is also observed, and regeneration through low ion-containing water cleaning effective. We shortened processing time by considering the optimal flow rate conditions and conductivity conditions and converting electrochemical modules into series or parallel.

Tomatoes in greenhouse are a widely cultivated horticultural crop worldwide, accounting for high production and production value. When greenhouse ventilation is minimized during low temperature periods, CO2 enrichment is often used to increase tomato photosynthetic rate and yield. Plant-induced electrical signal (PIES) can be used as a technology to monitor changes in the biological response of crops due to environmental changes by using the principle of measuring the resistance value, or impedance, within the crop. This study was conducted to investigate the relationship between tomato growth data, vital response, and PIES resulting from CO2 enrichment in greenhouse tomatoes. The growth of tomato treated with CO2 enrichment in the morning was significantly better in all items except stem diameter compared to the control, and PIES values were also higher. The growth of tomato continuously applied with CO2 was better in the treatment groups than control, and there was no significant difference in chlorophyll fluorescence and photosynthesis. However, PIES and SPAD values were higher in the CO2 treatment group than control. CO2 enrichment have a direct relationship with PIES, growth increased, and transpiration increased due to the increased leaf area, resulting in increased water absorption, which appears to be reflected in PIES, which measures vascular impedance. Through this, this study suggests that PIES can be used to monitor crops due to environmental changes, and that PIES is a useful method for non-destructively and continuously monitoring changes of crops.

This study was conducted to determine the optimal dipping time and concentration of gibberellin for improving the growth and quality of domestic cultivar 'Seolhyang' strawberry when using runner plants. Strawberry runner plants were collected on November 10th and soaked in GA3 concentrations of 50, 100, and 150 mg·L-1 for 30 and 60 minutes, respectively. After 75 days of planting, the growth results showed that in the 30-minute, 50 mg·L-1 treatment, the crown diameter was thicker and the T/R ratio was lower, indicating better plant vitality. Runner length increased with lower gibberellin concentrations, particularly promoting vegetative growth. Photosynthetic efficiency was more influenced by gibberellin concentration than dipping time, and using concentrations above a certain threshold acted as a stress factor for runner plants, leading to decreased photosynthetic efficiency. For enhancing seedling growth, soaking with 50 mg·L-1 of gibberellin for 30 minutes was found to be optimal. This study verified the effects of gibberellin treatment on strawberry runner plants to improve plant growth and quality, providing useful basic data for using gibberellin.

The type of radioactive waste that may occur in the process of nuclear power plant dismantling can be classified into solid, liquid, gas, and mixed waste. In addition, according to the level of radioactivity, it can be divided into high level, intermediate level, low level, and clearance level waste. In the case of solid radioactive waste, it is necessary to secure disposal suitability in order to deliver it to a disposal facility, so safe and efficient treatment of a large amount of radioactive waste generated during decommissioning is one of the most important issues. For the treatment of radioactive waste generated during decommissioning, technologies in various fields such as cutting, decontamination, melting, measurement, and packaging are required. Therefore, this study intends to present and application plan for decommissioning domestic nuclear power plants through overseas case studies for the treatment of radioactive waste expected to occur during nuclear power plant decommissioning.

The emergence of micropollutants in natural water sources due to the overuse of anthropogenic chemicals in industry and households has threatened the production of clean and safe tap water in drinking water treatment plants. Conventional physicochemical processes such as coagulation/flocculation followed by sand filtration are not effective for the control of micropollutants, whereas chemical oxidation processes (applying chlorine, permanganate, ozone, etc.) are known to be promising alternatives. Determining the optimum oxidant dose is important issue related to the production of disinfection by-products as well as unnecessary operating cost, and is made possible by simulations of target-micropollutant abatement based on kinetic model equation consisting of second-order rate constant (between the oxidant and the target) and oxidant exposure. However, the difficulty in determining oxidant exposure as a function of complex water quality parameters limits the field application of kinetic model equation. With respect to representative oxidants used in drinking water treatment plants, this article reviews two main approaches for determining oxidant exposure: i) direct measurement in situ and ii) prediction by empirical models based on key water quality parameters. In addition, we discussed research requirements to improve the predictive accuracy of the empirical models for oxidant exposure and to develop a rational algorithm to determine optimal oxidant dose by considering the priority of the target pollutants to be treated.

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.

국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.

Public complaints arising from centralized animal manure treatment plants are increasing due to the odors produced during animal manure treatment. Various physico chemical and biological methods are used to mitigate such odors. Still, many problems exist, such as a lack of fundamental data on odor generation characteristics and design standards for odor mitigation facilities. Therefore, this study evaluated the characteristics of NH3 and H2S gas produced from a centralized animal manure treatment plant. The centralized animal manure treatment plant selected in this study has a treatment capacity of 150 tons (animal manure and food waste) per day. The composting matrix was mechanically turned from 9:00 am to 6:00 pm on weekdays and not turned all day on weekends. The NH3 concentrations measured during the day on weekdays (96.4 ± 7.8 ppmv) were about 14% higher than on weekends (84.9 ± 15.9 ppmv). During the week, the ammonia concentration during the day was about 15% higher than at night, but there was no difference between day and night on weekends. The hydrogen sulfide concentration during the day (4,729 ± 3,687 ppbv) on a weekday was about 4.7 times higher than at night (1,007 ± 466 ppbv). The results of this study provide valuable information that is necessary for the operation of odor mitigation facilities. It is expected that the results will contribute to establishing an operational strategy that can reduce the energy required to collect exhaust gas.

Regulations on the concentration of boron discharged from industrial facilities, including nuclear power plants, are increasingly being strengthened worldwide. Since boron exists as boric acid at pH 7 or lower, it is very difficult to remove it in the existing LRS (Liquid Radwaste System) using RO and ion exchange resin. As an alternative technology for removing boron emitted from nuclear power plants, the electrochemical boron removal technology, which has been experimentally applied at the Ringhal Power Plant in Sweden, was introduced in the last presentation. In this study, the internal structure of the electrochemical module was improved to reduce the boron concentration to 5 mg/L or less in the 50 mg/L level of boron-containing waste liquid. In addition, the applicability of the electrochemical boron removal technology was evaluated by increasing the capacity of the unit module to 1 m3/hr in consideration of the actual capacity of the monitor tank of the nuclear power plant. By applying various experimental conditions such as flow rate and pressure, the optimum boron removal conditions using electrochemical technology were confirmed, and various operating conditions necessary for actual operation were established by configuring a concentrated water recirculation system to minimize secondary waste generation. The optimal arrangement method of the 1 m3/hr unit module developed in this study was reviewed by performing mathematical modeling based on the actual capacity of monitor tank and discharge characteristics of nuclear power plant.

Nuclear power plant decommissioning generates significant concrete waste, which is slightly contaminated, and expected to be classified as clearance concrete waste. Clearance concrete waste is generally crushed into rubble at the site or a satellite treatment facility for practical disposal purposes. During the process, workers are exposed to radiation from the nuclides in concrete waste. The treatment processes consist of concrete cutting/crushing, transportation, and loading/unloading. Workers’ radiation exposure during the process was systematically studied. A shielding package comprising a cylindrical and hexahedron structure was considered to reduce workers’ radiation exposure, and improved the treatment process’s efficiency. The shielding package’s effect on workers’ radiation exposure during the cutting and crushing process was also studied. The calculated annual radiation exposure of concrete treatment workers was below 1 mSv, which is the annual radiation exposure limit for members of the public. It was also found that workers involved in cutting and crushing were exposed the most.

자기공명영상(MRI) 장비의 조영제로 흔히 사용되는 가돌리늄(Gd)은 매우 안정된 상태로 하수처리과정에서 거의 제거되지 않고 수환경으로 유입된다고 알려져 있다. 따라서 본 연구에서는 세 가지의 공법으로 하수처리를 하는 부산 수영 하수처리장에서 채취한 하수 시료의 공정별 용존 희토류 원소의 제거율 및 수환경으로 배출되는 인위적 기원 Gd (Gdanth)의 배출량을 평가하고자 하였다. 용존 희토류 원소는 공정별 처리 단계에 따라 무거운 희토류 원소(Tb-Lu)에 비 해 가벼운 희토류 원소(La-Eu)에서 농도가 감소하는 경향을 보였다. 또한 일부 시료에서 나타난 음의(negative) Sm anomaly (<1)는 생물학적 제거 과정에서 Sm이 입자나 인산염과 흡착되어 함께 제거되었을 가능성을 시사한다. 모든 시 료에서 양의(positive) Gd anomaly (149±50, n=9)를 보였으며, 공정별로 측정된 Gd의 총 농도 중 Gdanth은 약 97% 이 상을 차지하는 것으로 나타났다. 이는 하수처리과정에서 Gdanth 이 거의 제거되지 않고 수영강 하류로 배출된다는 것을 의미한다. 일별 처리용량을 고려하여 각 공정에서 배출되는 Gdanth의 배출량은 259 mmol/day로 추정할 수 있다. 본 연 구의 결과는 하수처리장을 통해 수영만 연안으로 Gdanth이 지속적으로 배출될 것으로 예상되며, 향후 Gd의 중장기적인 관측이 필요함을 시사한다.

A 1,000 m3/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 μm showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.