• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.191-200
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• 2004

DAF process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when the freshwater blooms occut or raw water turbidity become high. Pre-sedimentation iS prepared in case when raw water turbidity is very high by rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while it is difficult to remove in sedimentation. One of the main concerns in adoption of DAF (Dissolved Air-Flotation) process is a high raw water turbidity problem. That is, DAF is not adequate for raw water, which is more turbid than 100NTU. In order to avoid this problem, pre-sedimentation basins are prepared in DAF plant to decrease the turbidity of DAF influent. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, DAF process coupled with sedimentation is suggested that pre-sedimentation with optimum coagulation prior to DAF would be appropriate.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.699-705
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• 2007

In this study, the improvement of the operation condition and the water quality in water treatment plant by operating information system(OIS) was evaluated for Ansan water treatment plant. The average flow rate of raw water in the year 2005(after constructing the OIS) appeared 15.6 % lower than that in the year 2004(before constructing the OIS). The mean value(12.37 NTU) of raw water turbidity in the year 2005 remained constant, or nearly so with that(12.06 NTU) in the year 2004. The average dosing rates of coagulant appeared 12.06 mg/L in the year 2005 which was higher than 10.31 mg/L in the year 2004. Furthermore, the average turbidity concentration of fresh water in the year 2005 appcared slightly better than that in the year 2004. From $COD_{Mn}$ and BOD concentration of raw water, the water quality in the year 2005 were better than those in the year 2004. The average concentration of $KMnO_4$ in the year 2004 and the year 2005 was 2.95 mg/L and 1.25 mg/L, respectively, and the average concentration of THMs in the year 2004 and the year 2005 appeared 0.038 mg/L and 0.025 mg/L, respectively. Therefore, the fresh water quality in the year 2005 was better than that in the year 2004. In this study, it is considered that the operation of Ansan water treatment plant may be optimized by OIS, and thus the OIS may be very useful method to improve the water quality.

• Journal of Life Science
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• v.9 no.3
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• pp.248-252
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• 1999

Effects of the ultrasonic treatment on plant represents antifeeding activity and chitin synthesis inhibition activity against diamondback moth (Plutella xylostella L.) by a leaf-dipping method at a concentration of 5,000ppm. Methanol extracts of leaves of the ultrasonic treatment on plant was sequentially partitioned with n-hexane, chloroform, ethlyacetate, butanol and water fractions, and bioassayed. Antifeeding activities were observed in n-hexane, chloroform and ethlyacetate fractions. N-hexane fraction has 94.6% of strongest antifeeding activity against P. xylostella. From the n-hexane sequentially partitioned showed H6 and H8 fractions of antifeeding activities against P. xylostella. And chitin synthesis inhibition activity against P. xylostella was obtained the methaol, n-hexane and water fractions.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1315-1322
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• 2010

A membrane bioreactor (MBR) was designed using polyvinylidene fluoride(PVDF)-type hollow fiber membrane modules with a treatment capacity of 10 ton/day. A pilot plant was installed in a sewage treatment plant and was operated with an intermittent aeration method which avoids any concentration gradient of suspended solids (SS) in the MBR. For continuous operation, the pilot plant was first tested with influent (mixed liquor suspended solid:MLSS of 1000-2000 mg/L) of aeration tanks in the sewage treatment plant. The MBR was pre-treated with washing water, 10% ethanol solution, 5% NaOCl solution and finally washing water, one after another. To demonstrate the effect of the MBR on sewage treatment, compared with conventional activated sludge processes, we investigated the relationships among permeate amount (LMH), change in operation conditions, influent MLSS level and sludge production. It was found that the optimum aeration rate and suction pressure were $0.3\;m^3$/min and 30~31 cmHg, respectively. Under stable conditions in aeration, suction pressure, influent flow rate and drainage, the SS removal efficiency was more than 99.99% even when the MLSS loading rate changes. Compared with conventional activated sludge processes, the MBR was more effective in cost reduction by 27% based on permeate amount and by 51.5% on sludge production.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.709-717
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• 2008

The field scale experiment which is constructed with four sets (0.88 ha for each set) of wetland (0.8 ha) and pond (0.08 ha) systems was performed to examine the effect of plant coverage on the constructed wetland performance and to recommend the optimum development and management of macrophyte communities. After six growing seasons of wetlands, plant coverage was about 100%. And the concentration of DO showed low value (1.0~5.4 mg/L). This is caused by a blighted plant consumed dissolved oxygen with decay in water column. As the result, water column went to be anaerobic conditions and T-N removal rate are 58~67%. Dead vegetation increased nitrogen removal during winter because it is a source of organic carbon which is an essential parameter in denitrification. However, wetland released phosphorus caused by a blighted plant and accumulation, the removal rate of phosphorus might be decreased. To rise of DO concentration, the three open-waters were constructed in cell 3 and 4. Cell 3 has two open-waters (width 10 m, depth 1.8 m) and cell 4 has one open-water (width 20 m, depth 1.8 m). As the result, DO concentration and treatment efficiency of nutrient and BOD were improved. In case that constructed wetland is operated for a long time, physical circulation structure such as open water help continuous circulation of aerobic and anaerobic conditions. Through the constructed open-water, treatment efficiency of phosphorus and nitrogen in wetland could be improved effectively.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.1-7
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• 2009

In order to select the water flooding-tolerant trees among Korean oaks, we cultivated the sapling of 6 deciduous oak species, Quercus acutissima, Q. mongolica, Q. variabilis, Q. dentata, Q. aliena and Q. serrata, under the water flooding treatment and the control, and analysed the growth difference among them. For comparing the growth between treatment and control, we measured 13 morphological and ecological traits, such as leaf Leaf number, leaf length, leaf width, leaf area, shoot length, stem length, stem diameter, root length, plant length, leaf weight, stem weight, root weight, plant weight. Q. serrata have no growth difference between water flooding treatment and control, but the rest 5 species showed the growth reduction in water flooding treatment. Tolerance of oak species to water flooding was risen in order of Quercus acutissima, Q. mongolica, Q. variabilis, Q. dentata, Q. aliena and Q. serrata. Thus, among Korean deciduous oaks, it is desirable to plant Q. serrata for flood plain restoration of river.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.233-243
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• 2018

In this manuscript, $35m^3/d$ NF unit was designed and applied for surface water treatment of the River Nile water. Intake of Embaba drinking water treatment plant was selected to install that unit at since; it has the lowest water quality index value through the examined 6 sites in greater Cairo area. The optimized operating conditions were feed and permeate flow, 40 and $7m^3/d$, feed pressure 2.68 bar and flux rate $37.7l/m^2h$. The permeate water was drinkable according to Egyptian Ministerial decree 458/2007 for the tested parameters (physic-chemical, heavy metals, organic, algal, bacteriological and parasitological). Single and double sand filters were used as pretreatment for NF membranes but continuous clogging for sand filters moved us to use UF membrane as pretreatment for NF membrane.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.402-409
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• 2004

I performed the research about the drinking water treatment by precoat filtration and activated carbon adsorption process in the D water treatment plant at Gwangju. D water treatment plant inlet water is supplied from Juam lake in Jeollanamdo. The results are as follows; 1. Element disk used in this experiment are R(pore size $10{\mu}m$), B(pore size $20{\mu}m$). And diatomaceous earth are A(cake pore size $3.5{\mu}m$), B(cake pore size $7{\mu}m$) and C(cake pore size $17{\mu}m$) 2. Filtrate of precoat filter during 30 min are B-C 10.2 > BB 5.7 > R-A 5.4 ($m^3/m^2$). 3. The water quality through B-C+AC and R-A+AC are DOC 1.76 mg/1, 1.288 m/l respectively. 4. total THMs produced by chlorination are $84.2{\mu}g/l$(B-C+AC), $66.11{\mu}g/l$ (R-A+AC), $97{\mu}g/l$ (rapid sand filtration water) respectively. 5. The R-A+AC and B-C+AC process can be substitute of CWTS.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.54-60
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• 2015

There are 5 purification plants with the adopted advanced water purification treatment process in Korea. Annual operating costs were 8,990 million won including purchase cost of oxygen and power usage charges. We need research to optimize, in the future, when considering the direction of domestic water treatment continues to adopt advanced water treatment process. In this paper, calculate the optimal operating costs by injected the oxygen gas, used power cost. approximately 25% of the operating costs can be reduced when injected the ozone gas is 1.0ppm than 2.0ppm, the necessary amount of oxygen is increased then power is lower. so operating costs are decided according to oxygen costs. On the other hand, high ozone concentration 2.0ppm, the necessary power is increased then amount of oxygen is lower. Therefore, in the case of G purification plant, the controlling factor of the input ozone concentration 2ppm, PID control operation by setting the concentration of over 10Wt% is efficient. The installed capacity is the more little the more better when considering on Ozone injection rate in the process of water treatment.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.273-282
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• 2008

The relationship between water deficit stress and monodehydroascorbate reductase (MDHAR) activity was determined in lettuce (Lactuca sativa L.) leaves under water stress condition imposed by with-holding water for 72 hrs. Relative water content determined in water deficit stressed lettuce leaves gradually reduced from 91.29% to 74.58%, and water content of medium drastically decreased 4.73% after quitting of irrigation. Hydrogen peroxide content in leaves subjected to water deficit stress rapidly increased, but soluble protein content rapidly decreased when those were compared to control plant. The relationship between relative water content and hydrogen peroxide content in stressed leaves positively correlated with $R^2$=0.8851, but soluble protein content reversely correlated with $R^2$=0.9826. Total chlorophyll content in stressed plant leaves was higher than that of control plant, and increased rapidly in early stage of treatment of both stressed and control plants. Carotenoid content was higher than that of control plant, and the ratio of carotenoid to total chlorophyll in stressed plant was higher as compared to control plant. As water deficit stress continued progressively, total ascorbate content in stressed plant leaves was a little higher than that of control plant. But dehydroascorbate (DHA) content within 6 hr of water deficit stress was higher than that of control plant, and then, content of control plant in 12 hr of stress treatment higher than that of stressed leaves. The activity of monodehydroascorbate reductase of cytosolic and chloroplastic tractions increased dramatically, and mRNA of MDHAR was highly detected by probing $^{32}P$-labeled single stranded MDHAR RNA of lettuce plant leaves subjected to water deficit stress. Relationship between MDHAR activity and relative water content and hydrogen peroxide highly correlated with $R^2$=0.9937 and 0.8645, respectively.