• Membrane Journal
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• v.22 no.3
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• pp.216-223
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• 2012

The effect of water back-flushing period (FT) was investigated in hybrid process of carbon fiber microfiltration membrane and photocatalyst for advanced drinking water treatment in this study, and compared with the previous study using alumina ultrafiltration membrane. The FT was changed in the range of 2~10 min with fixed 10 sec of BT. Then, the FT effects on resistance of membrane fouling ($R_f$), permeate flux (J) and total permeate volume ($V_T$) were observed during total filtration time of 180 min. As decreasing FT, $R_f$ decreased and J increased, which was same with the previous result using alumina ultrafiltration membrane. The treatment efficiency of turbidity was high beyond 99.2%, and the effect of FT was not shown on treatment efficiency of turbidity, which was different with the previous result. The treatment efficiency of organic matters was the lowest value of 65.6% at NBF, and it increased as decreasing FT, which was different with the previous result, too. The reason was that the membrane fouling phenomena could show a different mechanism depending on ceramic membrane materials.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.228-235
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• 2007

For efficient turbid water withdrawal in the Imha reservoir, a selective withdrawal facility was recently installed and operated during summer season of year 2006. In this research, CE-QUAL-W2 model was utilized to assess the efficiency of the selective withdrawal facility, in comparison with the original surface withdrawal, on turbid water management. Model calibration was carried out using data observed at four automatic monitoring stations in the reservoir. It was found that the model appropriately simulated, with the RMSE less than 5.2 NTU, the observed vertical and horizontal distributions of water temperature and turbidity as well as the location of maximum turbid water at each monitoring station. The analysis results showed that selective withdrawal is more effective in removing high turbid water than surface withdrawal as selective withdrawal contributed to reducing $35Mm^3$ of high turbidity water (> 100 NTU) in the reservoir by increasing outflows of high turbid water. Therefore, effective management of turbid water in the reservoir can be achieved by changing locations of intake depending on turbid water distribution conditions. The results of this study will provide some basic information for establishing better operation strategies to cope with turbid water problems.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.743-753
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• 2011

One of the most important water management issues of Soyang Reservoir, located in North Han River in Korea, is a long term discharge of turbid water to downstream during flood season. Installation of a selective withdrawal structure (SWS) is planned by the reservoir management institute as a control measure of outflow water quality and associated negative impacts on downstream water use and ecosystem. The objective of the study was to explore the effectiveness of the SWS on the control of outflow turbidity under two different hydrological years; one for normal flood year and another for extreme flood year. A two-dimensional (2D), laterally averaged hydrodynamic and water quality model (CE-QUAL-W2) was set up and calibrated for the reservoir and used to evaluate the performance of the proposed SWS. The results revealed that the SWS can be an effective method when the ${\Theta}$ value, the ratio between the amount of turbid water that containing suspended sediment (SS) greater than 25 mg/L and the total storage of the reservoir, is 0.59 during the normal flood year. However, the effectiveness of the SWS could be marginal or negative in the extreme flood year when ${\Theta}$ was 0.83. The results imply that the SWS is an effective alternative for the control of turbid water for moderate flood events, but not a sufficient measure for large flood events that are expected to happen more often in the future because of climate change.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.161-166
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• 2021

This study was on leaching test(KSLT) of the aggregate for the products to evaluate the characteristics of contaminants and the possibility of contamination arising from the aggregate. On the basis pH, conductivity, turbidity, TN, TP, COD and heavy metal contents in the aggregate increased as the particle size of the aggregate was smaller. The pH appeared to be 9.9~11.4 which is relatively higher than soil, however, heavy metal has investigated within the 1 region's standard value of soil pollution standards. From the leaching test, there is strong indication that the risk of pollution due to elution of pollutants gets higher with the smaller grain size. Especially conductivity and turbidity are the potential water pollution source and recycled aggregates of 10mm or less could be a potential pollution source since it could elute soluble matters and suspended solid, but there is no proper management standard for them. As a result of evaluating water pollution possibility of the aggregate, the pH displayed in items with a very high possibility of contamination, TN and TP did in item with a low possibility of contamination and on the other hand the heavy metals did in item with a very low possibility of contamination.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.720-724
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• 2011

Differences in sensory evaluation, physicochemical properties and antioxidant activities between green tea concentrations and tannase-treated green tea concentrations were measured in this study. The results showed that pH did not differ dependent on tannase treatment but antioxidant ability were slightly increased through tannase treatment without significant($p$ <0.05). However, the turbidity of the tannase-treated green tea concentration had significant difference to the non-treated concentration. The astringency, tested via sensory evaluation, decreased significantly after tannase treatment($p$ <0.05). Traces of epicatechin gallate(ECG) and epigallocatechin gallate(EGCG) also disappeared after the tannase treatment, due to the fact that the ester linkages in the catechin structure were broken by the tannase. It was concluded that tannase treatment of tea products is a very effective process for decreasing astringency and turbidity.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.1
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• pp.75-80
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• 2002

In this study, the initial number of bacteria before ozone sterilizing shows 290 per $1m{\ell}$ in RUN 1 and RUN 2 equally, but the removal rate shows more than 50% in RUN 1, and 100% in RUN 2 respectively when ozone injection amount is $0.28mg/{\ell}$. It is regarded as a satisfactory result that E-coli concentration without ozone contact is 890, rapid removal effect of E-coli is observed in $0.28mg/{\ell}$ of ozone, and E-coli is removed perfectly in $0.84mg/{\ell}$ of ozone. It is thought that an excellent efficiency is obtained for vibrio alginolyticus because the initial number of bacteria before ozone contact is positive, but it is altered to negative after ozone contact. CODcr shows the tendency which is somewhat reduced as the ozone injection is increased, but the general effect is appeared not so much, and it is thought that the tendency is caused by the reason that sea water contains much salt which is estimated as a component of CODcr, therefore it is regarded that ozone contact has not an important effect on salinity. It is thought that the frequency of changing salt water in the fish preserve of a sliced raw fish restaurant can be reduced to under the standard because NTU of 7 days after sea water injection is 0.70 in the experiment of turbidity, hut more than 50% of turbidity removal efficiency is appeared at $0.28mg/{\ell}$ of ozone injection, and it shows 70% at $0.84mg/{\ell}$ of ozone injection in RUN 1 and RUN 2 commonly.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.168-174
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• 2008

Diagnosis on setteability based on human operator's experimental knowledge, which could be established by long term operation, is a limit factor to construction of automation control system in wastewater treatment plant. On-line SVI(Sludge Volume Index) analyzer was developed which can measure SV30 automatically by image capture and image analysis method. In this paper, information got by settling process was studied using On-line SVI analyzer for better operation & management of WWTPs. First, SV30 detection algorithm was developed using image capture and image analysis for settling test and it showed that automatic detection is feasible even if deflocculation and bulking was occurred. Second, turbidity assessment model was developed using image analysis.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.415-420
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• 2001

Water usage in the semiconductor industries is dramatically increased by not only using bigger wafer from 8 inches to 12 inches but also by adapting new process such as Chemical Mechanical Planarization (CMP) process invented by IBM in late '80. However, The document published by International Semiconductor Association suggests the decreasing ultra pure water (UPW) use from 22 gallon/in$^2$in 1997 to 5 gallon/in$^2$ in 2012. The criteria will possibly used as exporting obstacle in the future. Generally, Solid content of CMP slurry is about 15wt%. The slurry is diluted with UPW before fed to a CMP process. When the slurry is discharged from the process as waste, it contains 0.1~0.6wt% of solid content and 9~10 at pH. The CMP waste slurry is discharged to stream with minimum treatment. In this study, to find optimum condition of coagulation for water recovery from the waste CMP slurry various condition of coagulation were examined. After coagulation far 0.1 wt% solid content of waste CMP slurry, the sludge volume was 10~15% after 30 min of sedimentation time. For the 0.5 wt%, sludge volume was 50~55% after one hour of sedimentation time. For more than 80% of water recycling, the solid content should be in the range of 0.1 to 0.2wr%. Based on the result of the turbidity removal, the Zeta Potential and the analysis of heavy metals, the optimum condition for 0.1 wr% of waste CMP slurry was with 20 mg/L of PACI at 4 to 5 of pH. The result showed that the optimum conditions fer the 0.1 wt% waste CMP slurry were 100mg/L of Alum at 4~5 of pH, 100 mg/L of MgCI$_2$at pH 10 to 11 and 100 mg/L of Ca(OH)$_2$at pH 9 to 11, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.601-608
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• 2015

Pollutants removal efficiency in pretreatment(GAC filter, multi-media filter, disk filter) and RO facilities was investigated for the Jeju Samyang spring water source where raw water intake has been stopped due to sea water intrusion. In addition, preliminary feasibility analysis was conducted between RO and groundwater intake systems. Turbidity removal in 4 different pretreatment processes was less than 25% due to low concentration of turbidity(i.e., less than 0.21 NTU), while multi-media filter is recommended for the pretreatment facility based on the low organic content in raw water as well as cheaper operation and maintenance cost. The average concentration of $Cl^-$ in raw water was 691.4 mg/L, while that of RO permeate was 9.1 mg/L(i.e., removal efficiency was 98.4%). In addition, TDS removal efficiency was 98.1%, which was quite high. The production cost for RO system($Q=4,000m^3/d$) was $362.1won/m^3$ considering installation, operation and maintenance cost for 30 years. While that of groundwater was $262.6won/m^3$ which was low compared to the RO system. However, it is recommended to introduce RO system for Samyang water source rather than new groundwater development because Samyang water source has been discharged to the sea without any usage, while groundwater can be used for other purpose as a sustainable water source.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.1-7
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• 2013

This study was on leaching test(KSLT, TCLP) of the aggregate for the products(RA-1) and for the site(RA-2) to evaluate the characteristics of contaminants and the possibility of contamination arising from the aggregate. On the basis pH, conductivity and heavy metal contents in the aggregate, RA-1 indicated higher than RA-2. As a result of the leaching test, the pollutants were eluted from the aggregate increased as the particle size of the aggregate was smaller. The pH in the aggregate had a strong alkali by a pH value of 9.0~12.3, the conductivity was higher in less than 10mm RA-1 due to the leaching of dissolved inorganic ions. The heavy metals satisfied the leaching standards of KSLT and less 10% was eluted from the aggregate. As a result of evaluating water pollution possibility of the aggregate, the pH displayed in items with a very high possibility of contamination, conductivity and turbidity did in item with a low possibility of contamination and on the other hand the heavy metals did in item with a very low possibility of contamination.