• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.624-629
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• 2013

The relation between performance maintenance conditions and those cost efficiency was studied to choose an optimum operating condition in the seawater desalination pretreatment system. A hollow fiber microfiltration module, which was developed with domestic technology, was tested with the various operating conditions such as chemically enhanced backwash cycles and design dosages of a cleaning chemical. Transmembrane pressure was measured to investigate membrane fouling status and cleaning degree. In addition, economic analysis was performed to compare water production costs by the operation condition. As a result, The operation mode III, chemically enhanced backwash at once a day with 100 mg/L of sodium hypochlorite (NaOCl) was selected. The concurrent evaluation between membrane filtration performance and its economic analysis will be suitable to choose an efficient optimum condition.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.563-570
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• 2004

Phased isolation intrachannel clarifier ditch process developed in this study is an enhanced biological nutrient removal process employing two ditches with intrachannel clarifiers. Bench-scale phased isolation ditch process was used to evaluate the system performance on municipal wastewater and detailed assessment of internal behavior in a ditch and each reactions. When the system was operated at the HRTs of 6~12hours, SRTs of 9~31 days, and cycle times of 4hours, the system showed removals of BOD, TN, and TP as high as 88~97%, 73~78%, and 65~90%, respectively. The internal behavior were well matched on each reactions such as nitrification, denitrification, and phosphorus release and uptake. As the SRT became longer, TN removal increased gradually, whereas TP removal decreased contrarily. However, the system was capable of producing an effluent TP concentration 1mg/L or less even at longer SRTs except the case of solids discharge by malfunction of intra-clarifier occurred by its geometrical limit. The system performance slightly decreased by hydraulic shock loading(increasing of influent flowrate and decreasing of system HRT). However, the higher system performance could be achieved again after four cycles. Thus, the system reliability could be successfully achieved short-term hydraulic shock loading that occurred in medium- and small-sized wastewater treatment plants suffering fluctuation of influent quality and flowrate during wet season.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.975-982
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• 2009

The purpose of this study is to offer informations about the current conditions and basic data of stream sediments in Busan city. So we first select 14 urban streams and collect sediment samples. Then, COD, proximate analysis, volatile solid, organic carbon content and elemental analysis were conducted to determine characteristics of the sediments. Results show that COD, volatile solid, Organic carbon content, T-N of sediment are determined in the range of 1.20~75.07 mg/g, 0.19~11.54%, 0.23~34.21% and 0.76~3.46%, respectively. Analysis data of sediments were compared with USEPA sediment quality standards and ontario sediment quality guidelines. As a result, when compared with COD, volatile solid and organic carbon content values, Bosucheon and Gudeokcheon are relatively heavily contaminated than the remainder sampling sites. But when compared with T-N values, all of sites were evaluated as seriously contaminated. Finally, for the determination of the correlations between sediment COD and moisture contents, ash contents, volatile solid, total organic carbon, total nitrogen and total carbon, linear model was fitted to the data using a least-squares algorithm. As a result, Linear model was well fitted to each data with good values of the correlation coefficient (r=0.9664~0.8501).

• The Korean Journal of Ecology
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• v.24 no.2
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• pp.101-109
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• 2001

We created an environmental forest on the basis of ecological design around the incineration plant of Jindo Engineering and Construction Co., Ltd., which is located in Jeongwang-dong, Siheung-si, Kyunggi-do. To get ecological information of this site, physico-chemical properties of soil on salt marsh, which is located close to the syudy site and of forest soil transported from other sites for ecological restoration were analyzed. Texture of salt marsh and transported soils were loam and sandy loam, respectively. pH, organic matter, T-N, available P, and exchangeable K and Na contents of salt marsh and transported forest soils were 6.7 and 5.4, 4.1 and 0.4%, 1.0 and 0.3mg/g, 46.7 and 6.8ppm, 521 and 207ppm, and 3.8 and 0.5mg/g, respectively. Introduced plants were selected among the dominant species of forests and the species composing the potential natural vegetation around the present study site. Those plants were selected again by considering the tolerances to air pollution and to salt, and their availability. Selected trees were Pinus thunbergii, Sophora japonica, Celtis sinensis, Quercus aliena, Q. serrata, Q. dentata, and Q. acutissima. Selected sub-trees were Albizzia julibrissin, Koelreuteria poniculata, and Styrax japonica and shrubs were Rhododendron yedoense var. poukhanense, R. mucronulatum, Callicarpa japonica, Euonymus alatus, E. japonica, and R. schlippenbachii. On the other hand, introduction of herbs was not considered except for Liriope platyphylla, which was ornamentally planted in one site. Planting bed of mound type was adopted to provide the fine drainage system. Mound was designed to furnish litter, A, B, and C layers simuating the profile of forest soil. Slope of mound was mulched by rice straw of 2cm in thickness to prevent for sliding of litter and soil in cases of strong wind or heavy rain. Height of mound was designed to secure more than 1 m by combining A and B layers. Narrow zones, in which mound with stable slope degree cannot be prepared, was designed to equip the standard soil depth with the introduction of stone for supporting. On the other hand, plants with shallow root system were arranged in some zones, in which satisfactory soil depth cannot be ensured. Plants were arranged in the order of tree, sub-tree, and shrub from center to edge on the mound to make a mature forest of a dome shape in the future. Dispersion of plants was designed to be random pattern rather than clumped one. Problems on creation of the environmental forest by such ecological design were found to be management or inspection by non-specialized project operators and inspecting officers, and regulations for construction without ecological background. Alternative plans to solve such problems were suggested.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.61-71
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• 1999

For a high-rate fermentation and recovery of organic acid, we have developed a new organic acid fermentation reactor with membrane filter, which is the most important part in the new advanced wastewater treatment system. The recovered organic acid is to be reused as an organic carbon source at denitrification process. Some experiments were conducted to compare the performance of acid fermentation at different SRTs, such as 5, 10, and 20 days. The total organic acid concentration produced during the runs was in the range of 2,100-2,900 (mgC/L). The conversion efficiency from substrate to organic acid reached to from 43% to 59%. The recovery rate of organic acid from substrate based on TOC was from 26% to 53%. Regardless of operational conditions, it has been able to maintain the membrane flux constantly, in the range of 0.4-0.46 ($m^3/m^2/day$). The transmembrane pressure drop was 0.2-0.3 (kg/cm) for 100 day's operation. The result of simulation is as follows. Organic removal efficiency of the new advanced treatment system is 95%. 73% of Nitrogen is removed. The removal efficiency of Phosphorus is 93%. By coqulation, soluble phosphorus is able to remove from the water treatment lines, which is impossible at conventional activated sludge system. The unit construction cost is 65000 (yen/m3) and it was 1.4 times than that of the standard activated sludge system. The unit operation cast is 7.7 ($yen/m^3/day$) and it was 1.3 times than that of the standard activated sludge system.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.70-77
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• 2012

The Ladle Furnace Slag, about 20% of the electric arc furnace slag, has high content of free CaO and free MgO, which generates the expansion collapse by hydration reaction. Although many researchers have been endeavoring to recycle the EAF reducing slag in construction fields, there is not found the effective recycling method up to now. However, the LFS(Ladle Furnace Slag) contains mineral composition of the system of calcium aluminate with high-reactivity. Therefore, it is possible to developed the quick setting property and the high strength at the early age by the rapid cooling. This study aimed to check the reactive minerals and predict the reactivity with water on the LFS discharged from different steel product plants. The test results show that many types of LFS has hydration reactivity and can use in construction field as a inorganic binder with the rapid setting property.

• Environmental Engineering Research
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• v.18 no.2
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• pp.103-108
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• 2013

Vietnam is a developing country with the rate around 5%-6% per year, especially in urban areas. Rapidly developed urban areas lead to stress for infrastructure and the water supply is also stressed. In Hanoi city, total water capacity from the manufactories is around one million cubic meters per day and almost the entire main water source is groundwater but it is not enough to supply all of Hanoi's people, especially in the summer. A demo project is implemented in Hanoi University of Civil Engineering (HUCE) to produce drinking water by using the rainwater and membrane system and supply for people. In this project, rainwater is collected on the rooftop of the lecture building with an area of around $500m^2$ and $100m^3$ volumetric rainwater tanks. Afterwards, the rainwater is treated by the micro-membrane system and supplied to the tap water. Total cost for construction, technology and operation in the first year is around USD 48,558. In the long-term (15 yr) if HUCE invests in the same system, with $20m^3$ volumetric storage tank, it can provide drinking water for 500 staffs in every year. The cost of investment and operation for this system is lower than 30% compared to buying bottled water with the price USD 1.8/bottle. The drinking water parameters after treatment are pH, 7.3-7.75; turbidity, 0.6-0.8 NUT; total dissolved solids, 60-89 mg/L; coliform, 0; heavy metal similar with water quality in the bottle water in Vietnam.

• Journal of Environmental Science International
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• v.31 no.8
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• pp.677-689
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• 2022

In order to photocatalytically treat organic matter (COD_Cr) and chromaticity effectively, chemical coagulation and sedimentation processes were employed as a pretreatment of the leachate produced from landfill in Jeju Island. This was performed using FeCl₃·6H₂O as a coagulant. For the treated leachate, UV/TiO₂ and UV/TiO₂/H₂O₂ systems were investigated, using 4 types of UV lamps, including an ozone lamp (24 W), TiO₂ as a photocatalyst, and/or H₂O₂ as an initiator or inhibitor for photocatalytic degradation. In the chemical coagulation and sedimentation process using FeCl₃·6H₂O, optimum removal was achieved with an initial pH of 6, and a coagulant dosage of 2.0 g/L, culminating in the removal of 40% COD_Cr and 81% chromaticity. For the UV/TiO₂ system utilizing an ozone lamp and 3 g/L of TiO₂, the optimum condition was obtained at pH 5. However, the treated COD_Cr and chromaticity did not meet the emission standards (COD_Cr: 400 mg/L, chromaticity: 200 degrees) in a clean area. However, for a UV/TiO₂/H₂O₂ system using 1.54 g/L of H₂O₂ in addition to the above optimum UV/TiO₂ system, the results were 395 mg/L and 160 degrees, respectively, which were within the emission standard limits. The effect of the UV lamp on the removal of COD_Cr, and chromaticity of the leachate decreased in the order of ozone (24 W) lamp > 254 nm (24 W) lamp > ozone (14 W) lamp > 254 nm (14 W) lamp. Only COD_Cr and chromaticity treated with the ozone (24 W) lamp met the emission standards.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.642-649
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• 2007

The effectiveness of add-on tertiary treatment processes for the polishing of the effluent of a biological nutrient removal (BNR) system from a modified $A^2/O$ process has been examined under the field condition with pilot-scale plants. The add-on treatment processes of 1) combined biofilm anoxic reactor and sand filtration, and 2) two-stage denitrification filter had been operated with various operating conditions. The experimental results indicated that two-stage denitrification filter could produced a better polished tertiary effluent. Filtration rate of $150m^3/m^2{\cdot}d$ for the 2-stage denitrifying filter could decrease the nitrate removal probably due to shorter detention time that caused insufficient reaction for denitrification. Two stage denitrification filter operated with M/N ratio of 3.0 and filtration rate of $100m^3/m^2{\cdot}d$ produced the tertiary effluent with nitrate and SS concentraitons of 2.8 mg/L and 2.3 mg/L, respectively. When the operating temperature reduced $30^{\circ}C$ to $18^{\circ}C$, $NO_3{^-}-N$ removal efficiency decreased from 73% to 68%.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1075-1086
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• 2008

In order to investigate the applicability and suitability of the industrial by-products to apply mono-layer cover system for non-sanitary landfill sites, 6 different industrial by-products, such as construction waste, bottom ash, gypsum, blast furnace and steel manufacture slags, and stone powder sludge, were evaluated. Various physicochemical and hydrodynamic properties of the industrial byproducts were investigated. The environmental safety was monitored using batch and long-term leaching tests as well. In addition, the flexibility of plants was observed by cultivating them in the industrial by-products. The results for physicochemical properties indicate that most of the materials considered appeared to be suitable for landfill cover. Particularly, the concentration levels of hazardous elements regulated by the Korean Law for Waste Management did not exceed the regulatory limits in all target materials. In addition, the concentrations of regulated elements for the Korean Soil Conservation Law were examined below the regulatory limits in most of materials considered, except for the stone powder sludge. The results of batch and long-term experiments showed bottom ash and construction waste were the most suitable materials for landfill cover among the industrial by-products considered. The results of plant studies indicate that the bottom ash among industrial by-products considered was most effective in developing vegetation on landfill site, showing fast germination and large growth index. At the final covering system made of mixture of soil and bottom ash, the optimum application rate of farmyard manure was observed to be 40-50 Mg/ha.