• Journal of Environmental Impact Assessment
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• v.32 no.2
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• pp.112-122
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• 2023

To restore the ecological function of contaminated soil and maximize the ecological services provided by the soil, besides the toxicity orrisk caused by pollutants, the functional aspects of the soil ecosystem should be considered. In this study, a method for evaluating the health of cleaned soil was presented, and the applicability of the proposed evaluation method was examined by applying it to soil treated with washing and landfarming. Productivity, habitat, water retention capacity, nutrient cycling, carbon retention capacity, and buffering capacity were used as soil health evaluation indicators. The results showed that the soil health was not completely recovered after remediation, and even in the case of the washed soil, the health was lower than before remediation. On the other hand, there was no significant change in soil quality due to oil pollution, but soil health deteriorated. Unlike the slightly improved soil quality after landfarming treatment, soil health was not completely restored. Therefore, the results of this study indicate that it is desirable to consider both soil quality and health when evaluating the remediation effect. The soil health evaluation method proposed in this study can be usefully utilized for the sustainable use of cleaned soil and to promote ecosystem services.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.271-282
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• 2020

Sewage treatment plants are social infrastructure of cities. The sewage distribution rate in Korea is reaching 94% based on the sewage statistics based in the year of 2017. In Korean sewage treatment plants, use of PAC (Poly Aluminum Chloride) accounts for 58%. It contains a large amount of impurities (heavy metal) according to the quality standards, however, there have been insufficient efforts to reinforce the standards or technically improve the quality, which resulted in secondary pollution problems from injecting excessive coagulant. Also, the increase in the use of chemicals is leading to the increases in the annual amount of sewage sludge generated in 2017 and the need to reuse sludge. As such, this study aims to verify the possibility of reusing sludge by evaluating the stability of heavy metals based on the injection of coagulant mixture during water treatment which uses the torrefield wood powder and natural materials, and evaluating the sedimentation and heating value of sewage sludge. As a result of analyzing heavy metals (Cr, Fe, Zn, Cu, Cd, As, Pb, and Ni) from the coagulant mixture and PAC (10%), Cr, Cd, Pb, Ni, and Hg were not detected. As for Zn, while its concentration notified in the quality standards for drinking water is 3 mg/L, only a small amount of 0.007 mg/L was detected in the coagulant mixture. Maximum amounts of over double amounts of Fe, Cu, and As were found with PAC (10%) compared to the coagulant mixture. Also, an analysis of sludge sedimentation found that the coagulant mixture showed a better performance of up to double the speed of the conventional coagulant, PAC (10%). The dry-basis lower heating value of sewage sludge produced by injecting the coagulant mixture was 3,378 kcal/kg, while that of sewage sludge generated due to PAC (10%) was 3,171 kcal/kg; although both coagulants met the requirements to be used as auxiliary fuel at thermal power plants, the coagulant mixture developed in this study could secure heating values 200 kal/kg higher than the counterpart. Therefore, utilization of the coagulant mixture for water treatment rather than PAC (10%) is expected to be more environmentally stable and effective, as it helps generating sludge with better stability against heavy metals, having a faster sludge sedimentation, and higher heating value.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.24-31
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• 2016

The increase of impervious area in cities caused the unbalanced water cycle system and the accumulated various contaminants, which make troubles as introducing into watershed. In Korea, most of rainfall in a year precipitate in a summer season. This indicate that non-point source pollution control should be more important in summer and careful rainfall reuse strategy is necessary. Accordingly, the aim of this study is to monitor the characteristics of rainfall contaminants harvested in roofs and to develop the rainfall treatment system which are designed to fit well in a typical domestic household including rain garden. The rain garden consists of peatmoss, gravel and san to specially treat the initial rainfall contaminants. For this purpose, lab scale experiments with synthetic rainfall had been conducted to optimize the removal efficiency of TN, TP and CODcr. After lab scale experiments, field scale rainfall treatment system installed as a pilot scale in a field. This system has been monitored during June to July in 2015 in four time rainfall events as investigating the function of time, rainfall, and pollutant concentrations. As results, high loading of pollutants were introduced to the rainfall treatment system and its removal efficiency is increased as increase of pollutant concentrations. Since it is common that the mega-size of rainfall treatment system is not attractive in urban area, small scale rainfall treatment system is promising to treat the non-point source contaminants from cities. In addition, this small scale rainfall treatment system could have a potential to water resue system in islands, which usually suffer the shortage of water.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.171-178
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• 2009

Water shortages are expected to be a major impact of climate change. This study examined the growth of Chinese cabbage seedling using reclaimed wastewater and waste nutrient solution as alternative irrigation resources. Generally, the concentration of nutrients, such as $K^+$, $NH_4^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$,$NO_3^-$, $PO_4^-$ and $SO_4^{2-}$, in waste nutrient solution was higher than that in wastewater. However, Chinese cabbage seedling irrigated with wastewater was supplied a higher concentration of $Na^+$ and $Cl^-$ than waste nutrient solution. The growth of Chinese cabbage seedling irrigated with waste nutrient solution was similar or higher than those irrigated with groundwater as control, while the growth of those irrigated with wastewater was similar to those irrigated with groundwater. The total nitrogen uptake in Chinese cabbage seedling irrigated with groundwater, waste nutrient solution from organic and inorganic hydroponic cultures, and wastewater was 5.47, 10.02, 5.20, and 4.59 mg/plant, respectively. The nitrogen uptake of Chinese cabbage seedling irrigated with waste nutrient solution from organic hydroponic substrates in a 50% lower dose than recommended was 8.34 mg/plant, which is higher than that of the cabbage irrigated with groundwater. Overall, the results suggest that waste nutrient solution and wastewater can be used as alternate water resources, and can allow a reduction in the amount of fertilizer needed to raise Chinese cabbage seedling.

• Journal of Wetlands Research
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• v.25 no.1
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• pp.35-47
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• 2023

Korean facility horticulture and hydroponic cultivation methods increase, requiring the management of waste water generated. In this study, the amount of fertilizer contained in the discharged waste liquid was determined. By evaluating this as a price, it was suggested to reduce water treatment costs and recycle fertilizer components. It was evaluated based on the results of major water quality analysis of waste liquid by crop, such as tomatoes, paprika, cucumbers, and strawberries, and in the case of P component, it was analyzed by converting it to the amount of phosphoric acid (P₂O₅). The amount of nitrogen (N) can be calculated by discharging 1,145.90kg·ha^-1 of tomatoes, 920.43kg·ha^-1 of paprika, 804.16kg·ha^-1 of cucumbers, 405.83kg·ha^-1 of strawberries, and the fertilizer content of P₂O₅ is 830.65kg·ha^-1 of paprika, 622.32kg·ha^-1 of tomatoes, 477.67kg·ha^-1 of cucumbers. In addition, trace elements such as potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) were also analyzed to be emitted. The price per kg of each item calculated by averaging the price of fertilizer sold on the market can be evaluated as KRW, N 860.7, P 2,378.2, K 2,121.7, Ca 981.2, Mg 1,036.3, Fe 126,076.9, Mn 62,322.1, Zn 15,825.0, Cu 31,362.0, B 4,238.0, Mo 149,041.7. The annual fertilizer loss amount for each crop was calculated by comprehensively considering the price per kg calculated based on the market price of fertilizer, the concentration of waste by crop analyzed earlier, and the average annual emission of hydroponic cultivation. As a result of the analysis, the average of the four hydroponic crops was 5,475,361.1 won in fertilizer ingredients, with tomatoes valued at 6,995,622.3 won, paprika valued at 7,384,923.8 won, cucumbers valued at 5,091,607.9 won, and strawberries valued at 2,429,290.6 won. It was expected that if hydroponic drainage is managed through self-treatment or threshing before discharge rather than by leaking it into a river and treating it as a pollutant, it can be a valuable reusable fertilizer ingredient along with reducing water treatment costs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.380-391
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• 1993

The experimental study was made to propose the treatment method of wastewater in the high-density fish culture system. The BOD to COD ratios of effluents were almost same to 0.65 in the eel-farm, but were various in the farm rearing together with tilapia etc. A BOD rate curve of the eel-farm effluent could be described mathematically by the equation, $BODu=14.1(1-10^{-0.222t})+30.9(1-10^{-0.035(t-8)})$. Nitrification in Biological Fluidized Bed(BFB) system to treat the fish-farm wastewater could be reduce ammonium level up to $65{\sim}79\%$ when ammonium loading rates were between 0.014 and 0.075g $NH_4/g$ BVS-day. Nitrification efficiency was decreased by organic matters in the wastewater when ammonium loading was low(0.014 g $NH_4/g$ BVS-day). T-N removal ratios were decreased to increase loading in denitrification process, because of low C/N ratio. Based on much higher biological mass concentrations, BFB system takes many advantages of a practical viewpoint, such as stability of treatment efficiency and reduction of necessary site area for the facility, as compared with conventional treatment systems.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.295-302
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• 2014

This study demonstrates a double-path CDI as an alternative of advanced wastewater treatment process. While the CDI typically consists of many pairs of electrodes connected in parallel, the new double-path CDI is designed to have series flow path by dividing the module into two stages. The CFD model showed that the double-path had uniform flow distribution with higher velocity and less dead zone compared with the single-path. However, the double-path was predicted to have higher pressure drop(0.7 bar) compared the single-path (0.4 bar). From the unit cell test, the highest TDS removal efficiencies of single- and double-path were up to 88% and 91%, respectively. The rate of increase in pressure drop with an increase of flow rate was higher in double-path than single-path. At 70 mL/min of flow rate, the pressure drop of double-path was 1.67 bar, which was two times higher than single-path. When the electrode spacing was increased from 100 to $200{\mu}m$, the pressure drop of double-path decreased from 1.67 to 0.87 bar, while there was little difference in TDS removal. When proto type double-path CDI was operated using sewage water, TDS, $NH_4{^+}$-N, $NO_3{^-}$-N and $PO_4{^{3-}}$-P removal efficiencies were up to 78%, 50%, 93% and 50%, respectively.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.420-426
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• 2012

The purpose of this study was to identify control points through microbiological hazard analysis in the manufacturing processes of starch noodles. Samples were collected from the ingredients, manufacturing processes, equipment and environment. Microbiological hazard assessments were performed using aerobic plate counts (APC), Enterobacteriaceae (EB), E. coli and five pathogens including B. cereus, E. coli O157:H7, L. monocytogenes, Salmonella spp., and S. aureus. The APC levels in raw materials were from 2.12 to 3.83 log CFU/g. The contamination levels after kneading were 4.31 log CFU/g for APCs and 2.88 log CFU/g for EB counts. APCs decreased to 1.63 log CFU/g and EB were not detected after gelatinization, but their levels slightly increased upon cooling, cutting, ripening, freezing, thawing, and separating. The reuse of cooling and coating water would be a critical source of microbial increase after cooling. After drying, APCs and EB counts decreased to 5.05 log CFU/g and 2.74 log CFU/g, respectively, and the levels were maintained to final products. These results suggest that the cooling process is a critical control point for microbiological safety, and the cooling water should be treated and controlled to prevent cross contamination by pre-requisite program.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.460-467
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• 2022

The purpose of this study is to enhance utilization of the waste nutrient solution (WNS) disposed at the hydroponic greenhouse. Several sets of testing were conducted to examine the effects of WNS: (a) a fertilizer effect, (b) soil column leaching, and (c) crop cultivation. The fertilizer effect test was applied in young radish cultivation by examining the growth characteristics of young radish and soil based on inorganic nitrogen according to the soil treatment of the nitrogen fertilizer (NF) and the WNS. The fertilizer effects and crop cultivation test were conducted with five treatments (A-E): A, non-treatment (water); B, 100% of NF; C, 70% of NF + 30% of WNS; D, 50% of NF + 50% of WNS; and E, 30% of NF + 70% of WNS. The soil column leaching test was conducted with three treatments: non-treatment (water), 100% of NF, 50% of WNS + 50% of NF. As a result, the chemical properties of the WNS were pH 6.0, EC 2.4dS·m^-1, total phosphorus (T-P) 28mg·L^-1, ammonium nitrogen (NH₄-N) 5.0mg·L^-1, and nitrate nitrogen (NO₃-N) 301mg·L^-1. The chemical properties of the soil were pH 5.51, EC 0.31dS/m, organic matter 2.08g·kg^-1, NO₃-N 9.64mg·kg^-1, and NH₄-N 3.20mg·kg^-1. The results of fertilizer effects showed that the ratio of 50% or less of NF and 50% or more of WNS was high in young radish growth. There was no statistically significant difference between the soil chemistry in the C-E treatments where WNS was mixed with NF and the B treatment where only NF was applied. As a result of the soil column leaching test, there was no significant difference in the concentrations of NO₃ and NH₄ in the treatment of 100% of NF and 50% of NF + 50% of WNS. The study indicates, if the mixed fertilizer of WNS and NF is applied in the soil cultivation of young radish, it will reduce the use of NF and environmental pollution. This also helps reduce production costs on farmers and increase the yield of young radish.

• Journal of dental hygiene science
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• v.9 no.1
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• pp.121-127
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• 2009

A comparative analysis was conducted through this study on tooth brushing and a use of auxiliary oral hygiene devices for oral hygiene for 287 S Health College students some of whom major dental hygiene and some of whom don't relate to the department, and then has drawn out the results as below. 1. Relating to the frequency of tooth brushing, 2-3 times a day was the utmost case in both departments(p < 0.05). 2. In use of toothbrush bristle, the students of dental hygiene department used medium bristle(51.2%), while the student of other department used soft bristle(51.5%)(p > 0.05). 3. In the term of tooth brush used, 2~5 months was the utmost case in both departments(p > 0.05). 4. In tooth- brushing method, all the student of both departments said they knew how to do it(p > 0.05). 5. In the acquisition of tooth brushing methods, the students of dental hygiene acquired it from dentistry 44.4%, and the students of other department from TV or Radio 47.5% (p > 0.05)which was a quite high rate. 6. In reference to recognition level on auxiliary oral hygiene devices, dental hygiene students said Yes 79.8%, and the other side students said No 63.9%(p < 0.05). In reuse of auxiliary oral hygiene devices, a great number of students of both departments said No (p < 0.05). 8. In reference to the chance to use auxiliary oral hygiene devices, 58.1% of dental hygiene students chose them with their own judgement, and 37.8% of other department students recommended by dentist's offices(p < 0.05). 9. Relating to the reason for not using auxiliary oral hygiene devices, 38.9% of the dental hygiene students said it's bothersome, and 56.7% of the other department students said they didn't know about these things(p < 0.05). 10. In the recognition level of dental floss, in knowing the way to use it, whether or not of using it, the students of both department showed a significant difference (p < 0.05). 11. In the recognition level of floss holder and the yes or not of using it, there was an insignificant difference(p > 0.05), while in understanding of it, there was a significant difference(p < 0.05). 12. Relating to the recognition level of electric tooth brush, yes or no of using it, there wasn't a significant difference(p > 0.05). 13. In the cognition level of rubber stimulator, yes or no of using it, there wasn't much difference, while in understanding to use it, there was a significant difference(p < 0.05). 14. In the understanding level of water pik, yes or not of using it, there wasn't a great deal of difference(p < 0.05), but in inquiry of whether or not of using it, there was no difference (p > 0.05), 15. In the understanding level of tongue scraper, whether or not of using it, there wasn't much difference(p > 0.05), but in understanding to use it, there was a great deal of difference(p < 0.05). 16. In the recognition of garglin, understanding of it, and whether or not of using it, the two departments didn't show a significant difference(p < 0.05).