• Nuclear Engineering and Technology
• /
• v.52 no.7
• /
• pp.1471-1480
• /
• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• Journal of Navigation and Port Research
• /
• v.44 no.6
• /
• pp.488-493
• /
• 2020

In this study, we sought to establish a vessel-discharge pollutant-treatment system recommended by IMO by first investigating advanced facilities overseas to help us understand and evaluate our domestic facility and needs. IMO recommends the installation and operation of port pollutant-storage facilities to adequately treat pollutants emitted by ships entering the port, and we reviewed the registration and operation of these facilities in IMO member countries, focusing on the IIII Code. Due to recent environmental regulations, additional facilities are required to treat the washing water discharged from equipment such as scrubbers mounted on the ship so pollutant-storage facilities must be established. Currently, Korea's ship-discharged wastes are being moved from ports to land waste-treatment plants, and their quantity and properties are not being monitored. Therefore, in this study, we improved monitoring of the discharged pollutants and investigated the proper arrangement of pollutant storage facilities as recommended by IMO. The system we established can help provide smooth service to incoming ships - and appropriate treatment of pollutants and will greatly benefit international maritime operations.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.4
• /
• pp.56-66
• /
• 2021

In this study, a waste heat recovery system was devised and the performances of components incorporated to recover the heat generated during the processing of aerobic liquid-composting in a livestock manure treatment facility were analyzed. In addition, the availability of recovered heat was confirmed. The heat generated by liquid fermentation in the livestock manure treatment facility was also checked. Experimental temperatures were set at 35, 40, and 45 ℃ based on considerations of the uniformity of aerobic liquid-composting fermentation tank temperature and its operating range (34.5 ~ 43.9 ℃). Recovered heat energies from the combined heat exchanger, which consisted of PE and STS pipes, were 53.5, 65.6, 74.4 MJ/h, The heat pump of capacity 5 RT was heated at 95.6, 96.1, 98.9 MJ/h and the heating COPs of the pump were 4.53, 4.62, and 4.65, respectively. The maximum hot water production capacity of the heat exchanger assuming a fermentation tank temperature of 45 ℃ confirmed an energy supply of 56 360 kcal/day. The heating capacity of the FCU linked to the heat storage tank was 20.8 MJ/h, and the energy utilization efficiency was 96.1%. When livestock manure was dried using the FCU, it was confirmed that the initial function rate was reduced by 50.5 to 45.8 % after drying.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.6
• /
• pp.7-14
• /
• 2008

The main objective of sewer rehabilitation is to improve its function while eliminating inflow/infiltration (I/I). If we can identify the amount of I/I for an individual pipe, it is possible to estimate the I/Is of sub-areas clearly. However, in real, the amount of I/I for an individual pipe is almost impossible to be obtained due to the limitation of cost and time. In this study, I/I occurrence of each sewer pipe is estimated using AHP (Analytic Hierarch Process) and RPDM (Rehabilitation Priority Decision Model for sewer system) was developed using the estimated I/I of each pipe to perform the efficient sewer rehabilitation. Based on the determined amount of I/I for an individual pipe, the RPDM determines the optimal rehabilitation priority (ORP) using a genetic algorithm for sub-areas in term of minimizing the amount of I/I occurring while the rehabilitation process is performed. The benefit obtained by implementing the ORP for rehabilitation of sub-areas is estimated by the only waste water treatment cost (WWTC) of I/I which occurs during the sewer rehabilitation period. The results of the ORP were compared with those of a numerical weighting method (NWM) which is the decision method for the rehabilitation priority in the general sewer rehabilitation practices and the worst order which are other methods to determine the rehabilitation order of sub-areas in field. The ORP reduced the WWTC by 22% compared to the NWM and by 40% compared to the worst order.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.5
• /
• pp.903-915
• /
• 2011

Recently, anaerobic methane production of agricultural waste biomass has received increasing attention. Until now domestic BMP (Biochemical methane potential) studies concerned with agricultural waste biomass have concentrated on the several waste biomass such as livestock manure, food waste, and sewage sludge from WWTP (Waste water treatment plant). Especially, the lack of standardization study of BMP assay method has caused the confused comprehension and interpretation in the comparison of BMP results from various researchers. Germany and USA had established the standard methods, VDI 4630 and ASTM E2170-01, for the analysis of BMP and anaerobic organic degradation, respectively. In this review, BMP was defined in the aspect of organic material represented as COD (Chemical oxygen demand) and VS (Volatile solid), and the influence of several parameters on the methane potential of the feedstock was presented. In the investigation of domestic BMP case studies, BMP results of 18 biomass species generating from agriculture and agro-industry were presented. And BMP results of crop species reported from foreign case studies were presented according to the classification system of crops such as food crop, vegetables, oil seed and specialty crop, orchards, and fodder and energy crop. This review emphasizes the urgent need for characterizing the innumerable kind of biomass by their capability on methane production.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.1
• /
• pp.273-283
• /
• 2014

With the introduction of COBie (Construction Operation Building Exchange) in BIM technology enabling an automatic transfer of design and construction information to operation and management (O&M) phase, the BIM centric O&M management system development process has been tested on the subject of architectural types of building. However, for now, there is a need to investigate the technical feasibility of COBie application to civil structures including industrial facilities. This study takes both "O&M Guideline for Public Wastewater Treatment Plant" and a real wastewater treatment plant into account for the purpose, in which the latter is intended to supplement the result of the first. The findings are three-folds: (1) COBie, as an asset modeling, is not sufficient enough to encompass commissioning data, (2) more relevant IFC development and family library build-up useful to modeling wastewater treatment plant is imperative, and (3) well-planned coordination and organization of COBie data-set in line with O&M practice will enhance the feasibility of the COBie in industrial facilities. The result could be used for a basis study for COBie application, particularly in industrial facilities.

• Journal of Animal Environmental Science
• /
• v.5 no.3
• /
• pp.189-196
• /
• 1999

Anaerobic digestion is a naturally occuring microbial process involving the decomposition of organic materials such as livestock manure. This study explores the effect of the operating conditions, HRT (Hydraulic Retention Time) and feeding frequency on treatment efficiency for digestion of pig slurry, which has been one of most difficult organic waste for proper treatment in livestock production industry in Korea at the present time. The pilot-scale CSTR of 5 m3 in volume was designed. manufactured, and operated at the temperature of 35$\pm$1$^{\circ}C$. The digester was designed to hydraulically stir for complete mixing and to supply heat from the water bath to maintain mesophilic temperature. The HRT of the digester for Test 1 and Test 2, and Test 3 was set for 17 days and 13 days respectively and pig slurry was fed once a day with 300$\ell$ each for Test 1 and Test 3, while twice with 150$\ell$each for Test 2. Test 2 showed better performance by increase of 4% in VS removal efficiency and 5% in biogas production rate. This is mainly attributed to smaller temperature drop by feeding frequently with half amount, which eventually led to lesser impact on anaerobic mocrobes in the digester. Test 2 maintained optimum pH 7.8 which uplifted the activaton of sulfur-reduction bacteria, alkalinity of around 4,000mg/$\ell$, VA of over 3,000mg/$\ell$ for whole period of experiment. Further research may require to provide the practical operation strategy of anaerobic treatment system for treatment of pig slurry.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.11 no.3
• /
• pp.229-243
• /
• 2013

An in situ solute migration system was designed and installed in KAERI Underground Research Tunnel (KURT) constructed in the site of Korea Atomic Energy Research Institute (KAERI) in order to investigate the migration and retardation of non-sorbing and sorbing tracers through a rock fracture. The system is composed of three main parts including injection, extraction, and data treatment. For the selection of a water-conducting fracture, boreholes were drilled. The fractures in the drilled boreholes were investigated using borehole image analysis using borehole image processing system (BIPS). The results of BIPS analysis showed that borehole YH 3-1 and YH 3-2 were connected each other. Moreover, hydraulic tests were carried out to determine the test section with connectivity for the in situ experiments. The in situ solute migration experiments were accomplished to understand the migration of solutes through fractures in KURT using non-sorbing tracers which were fluorescein sodium, eosin-B, bromide and sorbing tracers which were rubidium, nickel, zirconium, and samarium.

• Membrane and Water Treatment
• /
• v.15 no.1
• /
• pp.21-29
• /
• 2024

1H,1H,2H,2H-perfluorodecytriethoxysilane (C₁₆H₁₉F₁₇O₃Si) be successfully applied to the hydrophobic modification of Al₂O₃ tubular ceramic membrane. Taking the concentration of modification solution, modification time, and modification temperature as factors, orthogonal experiments were designed to study the hydrophobicity of the composite membranes. The experiments showed that the modification time had the greatest impact on the experimental results, followed by the modification temperature, and the modification solution concentration had the smallest impact. Concentration of the modified solution 0.012 mol·L^-1, modification temperature 30 ℃ and modification time 24 h were considered optimal hydrophobic modification conditions. And the pure water flux reached 274.80 kg·m^-2·h^-1 at 0.1MPa before hydrophobic modification, whereas the modified membrane completely blocked liquid water permeation at pressures less than 0.1MPa. Air gap membrane distillation experiments were conducted for NaCl (2wt%) solution, and the maximum flux reached 4.20 kg·m^-2·h^-1, while the retention rate remained above 99.8%. Given the scarcity of freshwater resources in coastal areas, the article proposed a system for seawater desalination using air conditioning waste heat, and conducted preliminary research on its freshwater production performance using Aspen Plus. Finally, the proposed system achieved a freshwater production capacity of 0.61 kg·m^-2·h^-1.

• Journal of Korean Society on Water Environment
• /
• v.22 no.6
• /
• pp.1119-1122
• /
• 2006

Aeration by using diffusers usually requires approximately 50~90% of the total electricity needed to operate WWTP (WasteWater Treatment Plant)s. Accurate evaluation of the oxygen transfer efficiency for an aeration system, and recommendation of a better alternative may help saving WWTP operational costs. Appropriate techniques and methods to achieve this purpose have not been introduced in Korea. In this study, in-process analysis was performed for a coarse bubble aeration system by the off-gas method to evaluate its applicability in Korea. To accomplish this analysis, an off-gas test, unsteady-state clean water test and steady-state off-gas column test was conducted and comparisons to other aeration systems were made. The ${\alpha}$ and the F estimated from the results of the unsteady-state clean water test and the steady-state off-gas column test were 0.61 and 0.90 respectively in a coarse bubble aeration system. The comparison of P.E tube diffusers laid out single spiral roll and ceramic dome diffusers laid out full floor coverage showed that the oxygen transfer efficiency of the coarse bubble aeration system was less than or similar to other aeration systems. But, airflow rates per unit area were 4~5 times greater than other aeration systems. In regards to the oxygen transfer efficiency for airflow rates per unit area, a retrofit to higher efficiency diffusers was urgently needed. This study showed proved that off-gas methods can apply to evaluate diffuser performances to estimate operating factors and to compare other aeration systems in Korea.