• Journal of Environmental Science International
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• v.13 no.6
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• pp.571-579
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• 2004

There is a need to improve the efficiency of the existing sanitary treatment facilities, because the effluent standard becomes more stricter and septic sludge increased. Thus, operating processes of sanitary treatment system in M city changed with installation of additional facilities. Process modifications were as follows: Dilution water was added to the next process after primary aeration tank. Some secondary sedimentation sludge was recycled to primary aerator so that most of the organics were stabilized in primary aeration tank under automatic control of dissolved oxygen. The line of effluent from dewatering process flowing to the activated sludge tank was changed to the primary aerator. The primary sedimentation sludge line was linked to a thickener. Polymer was added to the activated sludge tank. The effluent of primary aerator and aerobic digester was recycled from the 5th to the 1st sector. As consequencies of above process modifications, the improvement of removal efficiency was achieved as BOD 54%, COD 42%, SS 61%, T-N 39%, and T-P 12%, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.187-193
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• 2007

Reynolds and Froude numbers, along with tracer tests, have been widely used to estimate hydrodynamics in full-scale horizontal sedimentation basin in water treatment plants (WTPs). In spite of this, the former numbers do not reflect actual operating conditions, instead most often being based on the dimensions of the structures. The index and graphic analyses most often used were found to be too subjective to accurately analyze tracer test results. In order to overcome these limitations, dispersion number was applied for analysis of tracer test results. Tracer tests were conducted in eight full-scale sedimentation basins in six WTPs, and then analyzed by index and graphic analyses as well as by dispersion number. The dispersion number was more useful as an indicator of the hydrodynamic behavior in the basin. It was also found that as dispersion number decreased, flow approached the ideal for plug flow in which case, higher sedimentation efficiency could be expected.

• Korean Journal of Hydrosciences
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• v.10
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• pp.73-83
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• 1999

The intake towers of Buyeo W.T.P. in Keum river have being suffered from the sedimentation problems since the beginning of the operation. Impellers of the intake pumps have to the frequently changed due to the serious surface erosion. Thousands tons of sands are entrapped in the intake towers and equalization chambers of W.T.P. every year. Site surveying and numerical analysis were carried out to suggest an appropriate solution by understanding the general sedimentation regime of Keum river and causes of the sedimentation in the intake towers. Origin of the sediment could be found by the desk and site inspections. The validity of the used numerical models was examined by comparisons between the calculated bydraulic values and the measured ones during the specific periods. The design flow rate for the prediction of the future sedimentation regime of the rever was studied. The efficiency of the sediment control measures was also examined with the verified numerical models. Finally, it was found that the best solution could be a combination of three sediment control measures; increase the clearance between river bed and inlet, construct jetties at 2 kilometers upstream from the intake towers, and put vanes at the right side of the intake towers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.1
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• pp.8-14
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• 1993

To investigate selection efficiency for protein content and hardness in a wheat breeding program, two crosses were made between soft wheat (SW) ‘Chokwang’ and hard wheat (HW) ‘Lancota’, and between HW ‘Suwon 210’ and SW ‘Atlas 66’. F2 progeny lines from the crosses were separated into 4 groups as HW + high protein (HP), HW + low protein (LP), SW + HP and SW + LP by measuring protein content and sedimentation value in F4 generation. The subsequent populations were tested for protein content, sedimentation value, mixogram pattern and bread quality. HP group selected from F4 again had a higher protein content in F5 generation than LP group, but there was no significant difference between two groups in F6 generation. In sedimentation value, the significant difference was recognizable only between the groups of HW + HP and. SW + LP. Plant based investigation in F6 revealed that the distribution pattern for protein content and sedimentation value shifted from the low to high by the four groups with the order of SW + LP, HW + LP, SW + HP, HW + HP. Such a trend was most noticeable in the progenies of the cross between ‘Suwon 210’ and ‘Atlas 66’. Mixogram pattern that shows flour characteristics differed greatly among the groups, indicating a high selection efficiency for the traits. Bread volume in F6 of HW + HP was found to be higher than that of SW + LP, only from the cross between ‘Suwon 210’ and ‘Atlas 66’.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.429-433
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• 2014

In this study, the morphology and the x-ray quantum efficient of mercury oxide (HgO) and lead oxide (PbO) sensors derived by particle sedimentation method were discussed. In the pursuit of this purpose, we investigated the electrical characteristics and the x-ray quantum efficiency of various thicknesses of HgO and PbO films in mammographic x-ray energy. We have therefore developed a particle-in-binder sedimentation method of fabricating large area polycrystalline films onto transparent glass substrates coated with indium tin oxide. We are currently optimizing the growth method to improve the quantum efficiency with the ultimate goal of obtaining as quantum efficiency close to that of single crystal performance. Our future efforts will concentrate on optimization of large area film growth techniques specifically for deposition on a-Si:H flat panel readout arrays.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.3
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• pp.107-111
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• 2008

Usually, flow mediation earth and settling pond etc. of processing plant to handle water or wastewater. Mediation is the wastewater that flowed past settling pond than material of heavy particles, water weight colloid particles that big solids are removed but are suspensibility material settlement exclusion impossible. So, we need flocculation and coagulation action to remove materials from this colloid state. Flocculation and coagulation by addition of chemical agents forms floc settle size. That is, shorten the sedimentation time and quality of processing water because promoting sedimentation doing to do fines or suspended solids and colloid can materials large size and also, flocculation to annex efficiency of filtration augment. Therefore, I executed this research to prove that COD efficiency for wastewater by using inorganic coagulant.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.2
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• pp.153-162
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• 2021

The effects of activated carbon originated Ballasted Flocculant (BF) on the settleability of activated sludge and the recovery of BF by Hydro-cyclone (HC) were analyzed experimentally. Two kinds of BF (M-I: 125-250 ㎛, M-II: 250-425 ㎛ in dia.) and three kinds of activated sludges with different SS concentration (2,300-7,100 mg/L) were applied for this study. With the dosage variation of BF from 0.14 to 1.3 g-BF/g-SS, we could obtain 24-31% improvement in SV30 (Sludge Volume after 30min sedimentation) for the lowest SS concentration sludge (2,300 mg/L). Whereas the SV30 improvement was much higher as 44-48% for the highest SS concentration sludge (7,100 mg/L). The settling characteristics of the sludge with BF followed Vesilind model the best among three models (Vesilind, Takacs and Cho model). HC could effectively separate BF with the separation efficiency of 70-90% and over 95% separation efficiency could be obtained when the HC was applied twice.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.357-362
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• 2016

Improvement of the solid-liquid separation efficiency in the secondary sedimentation tank of the biological treatment process, is known to be increasing effectiveness of the overall system operation. Sewage treatment plant effluent SS is composed of most organic substances. In order to reduce the SS component in the secondary sedimentation tank discharge, fine SS components constituting the heterogeneous should be increased by its own aggregation (self flocculation), so that can be deleted through their precipitation. So, it is improved through using the installation of double rectification wall in this secondary tank. In case, sewage is rapidly increased due to the daily change of the influent water, it was confirmed that suspended solids caused by the impact load are processed stably. Therefore, there is a need for a facility installation which can be its own aggregation for reduction suspended solids in secondary sedimentation tank.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.665-674
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• 2005

The aim of this study is to evaluate 3 types of sedimentation basins: dredging, shield skirt and auxiliary dam, constructed at inlets of two irrigation reservoir and to estimate the most beneficial type and fitted size, SAR(surface to area ratio), for pollutant removal efficiency(RE). For this, RE of major water quality items and change of physicochemical properties in sediments before and post construction of sedimentation basin(SB) were investigated. RE depended on SB types, water quality items and survey times with wide range from $-87\%$ to $92\%$. Long term overall removal efficiency by ROC(regression of concentration) method were $18\%$ in dredging, $29\%$ in shield skirt and $42\%$ in auxiliary dam type. There was a change of physicochemical properties in sediments at auxiliary dam type, while a slight change at dredging and shield skirt type. In comparison to RE, SAR and hydraulic retention time at 3 types of SB, auxiliary dam type was the most beneficial one. Thus, it is recommended that SB would be constructed in completely separated structure from water body of a reservoir with SAR ranged from 0.7 to $1.0\%.$

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.676-681
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• 2005

This study was researched for disinfection by-products (DBPs) by preozonation, prechlorination and/or postchlorination. DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), halonitriles, and aldehydes were analyzed by the treatment steps of prechlorination, preozonation, sedimentation, filtration, and postchlorination comparatively. THMs were detected as $52.20{\mu}g/L$ after prechlorination and decreased during sedimentation and filtration process. The HAAs and aldehydes increased more during preozonaiton than prechlorination. However, chlorinated DBPs and aldehydes increased more by postchlorination. Chlorinated DBPs formed by preozonation increased 26% more than the chlorination process. If aldehydes were included in the total DBPs, DBPs increased up to 39% by preozonation. Preozonation could increase the removal efficiency of organic carbon during the coagulation and sedimentation processes. Ozonation might produce aldehydes that are not permitted for drinking water regulations. Also, DBPs were produced by preozonation than by chlorination. These results would bring a need for alternative disinfection studies to decrease DBPs.