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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Society of Water and Wastewater
Journal Basic Information
Journal DOI :
The Korean Society of Water and Wastewater
Editor in Chief :
Volume & Issues
Volume 23, Issue 6 - Dec 2009
Volume 23, Issue 5 - Oct 2009
Volume 23, Issue 4 - Aug 2009
Volume 23, Issue 3 - Jun 2009
Volume 23, Issue 2 - Apr 2009
Volume 23, Issue 1 - Feb 2009
Selecting the target year
Survey on sewerage operation/management planning for flooding (I)
Ryu, Jae-Na ; Hwang, Sung-Hwan ; Oh, Je-Ill ; Hyun, In-Hwan ; Kim, Young-Ran ; Kim, Chan-Soo ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 265~270
A nationwide questionnaire survey was conducted to investigate the actual conditions of local authorities in operating and maintaining sewerage systems especially for urban flooding. The questionnaire includes the incidences of flooding since 1980, the existence of any guidance for preventing flood damage and the design frequency currently used for sewers in each local authority. Among 160 local authorities responded to the survey, 95(59.3%) has experienced flooding more than once since 1980 while only 36(37.9%) of the 95 has prepared operation/maintenance guidelines for flooding. Most of the respondents have applied the 10 year design frequency for sewer design and 57(35.6%) of them agreed to adjust the 10 year design frequency regulation.
Survey on sewerage operation/management planning for flooding (II)
Ryu, Jae-Na ; Cha, Young-Joo ; Oh, Je-Ill ; Hyun, In-Hwan ; Kim, Young-Ran ; Chang, Dae-Hwan ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 271~276
Under current design standard, sewers are designed to drain stormwater generated up to 10 year return period of storms. This implies sewer flooding could occur from rainfall exceeding a 10 year return period. 5, 10, 20 and 30 year return period of storm intensities were calculated for 22 locations (cities) of meterological stations over the nation and compared to the recorded rainfall intensities for the last 30 years. The comparison resulted in the numbers of year maximum rainfall intensities exceeded each return period. Using the questionnaire survey for "the incidences of flooding since 1980' of the previous paper (Survey on sewerage operation/management planning for flooding (I)), the actual rainfall records on the date of flooding events were analyzed to demonstrate the number of flooding events caused by the exceedance of sewer capacity. For the last 30 years, more than 6 years of year maximum rainfall intensity (20%) were larger than the 10 year return period of storm in 4 cities of the 22 used for the first analysis. The number of rainfall records that exceeded the 10 year return period was 50 of the 260 actual flooding events investigated from the survey.
Determination of Optimal Time to Replace On-S Water Pipeline by Analyzing Water Main Failures and Economical Efficiency
Kim, Jong-Sin ; Jung, Kwan-Sue ; Bae, Chul-Ho ; Lee, Doo-jin ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 279~285
In this study, applied to the industrial water service, it is verified feasibility of break-even analysis method which has not been introduced in Korea. The On-san water pipeline of 7.1km among the Ul-san industrial water service is selected and the optimal replacement time calculated by break-even analysis method is year 2033 to 2044 which will be 53 to 67 years since the pipes were buried. If indirect cost such as the value of lost water and traffic disruption, service interruption, etc. is calculated as 30 and 100% of the direct cost, the financially optimum replacement time is advanced 3 to 9 years. These ways present rational criteria to establish long-term plan for budget and to execute the limited budget efficiently.
Analysis of the wastewater characteristics variation in sewerage by rehabilitation
Jung, Si-Mon ; Park, In-Hyeok ; Park, Jung-Ha ; Ha, Sung-Ryoung ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 287~293
The study involved the measurement of flowrate and BOD in the Yeoju area and analyzed annual sewerage data by the I/I analysis technique which is common in Korea. The results of this study are as follows. The I/I for the Y-1 site before maintenance and after the completion of the whole process was reduced from 62% to 16.1% respectively with respect to maximum sewage flow per day. The average quality of water increased. The study measured the Y-2 site from a point of time corresponding to an 80% process rate and its I/I rate went up a little from 8.5% to 11.5%. At the Y-3 site, the I/I rate went up a little from 11% to 13.8%, while little change was noted in the average water quality. At the Y-4 site, the I/I rate was reduced from 43% to 16.9% and its average water quality went up. At the Y-5 site, the I/I quantity went up a little however its average water quality also went up largely. Therefore, it was concluded that the Y-5 site showed great improvement due to the sewer pipe maintenance.
Calculation of Probability of System Failure for Pipe Network with Surge Tank regarding Unsteady Flow
Kwon, Hyuk-Jae ; Lee, Cheol-Eung ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 295~303
In the present study, a reliability analysis calculating the probability of system failure has been performed using cut set and results of numerical analysis for unsteady flow in pipe. Especially, the probability of system failure has been evaluated regarding the effect of valve closure which is a really important activity in operation of piping system. In spite of small amount of demand, it was found that fast valve closure can generate high probability of system failure. Furthermore, it was confirmed that surge tank can reduce the unsteady effects and probability of system failure in water distribution system. From the results, it was found that the unsteady flow has a significant effect on the probability of system failure Furthermore, it was able to find which pipe or cut set has high probability of system failure. So it could be used to determine which pipe or cut set has a priority of repair and replacement. Therefore, reliability analysis regarding unsteady flow has to be performed for the planning, designing, maintenance, and operation of piping system.
A Statistical Methodology for Evaluating the Residual Life of Water Mains
Park, Su-Wan ; Choi, Chang-Log ; Kim, Jeong-Hyun ; Bae, Cheol-Ho ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 305~313
This paper provides a method for evaluating a residual life of water mains using a proportional hazard model(PHM). The survival time of individual pipe is defined as the elapsed time since installation until a break rate of individual pipe exceeds the Threshol Break Rate. A break rate of an individual pipe is estimated by using the General Pipe Break Model(GPBM). In order to use the GPBM effectively, improvement of the GPBM is presented in this paper by utilizing additional break data that is the cumulative number of pipe break of 0 for the time of installation and adjusting a value of weighting factor(WF). The residual lives and hazard ratios of the case study pipes of which the cumulative number of pipe breaks is more than one is estimated by using the estimated survival function. It is found that the average residual lives of the steel and cast iron pipes are about 25.1 and 21 years, respectively. The hazard rate of the cast iron pipes is found to be higher than the steel pipes until 20 years since installation. However, the hazard rate of the cast iron pipes become lower than the hazard rates of the steel pipes after 20 years since installation.
A study on the effects of environmental investment and costs on environmental performance
Park, Gwang-Dueg ; Park , No-Suk ; Kim, Seong-Su ; Seo, In-Seok ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 315~320
This study found that introduction of environmental systems and increased environmental investment have a major impact on K company's sustainable development. The analysis indicated that the environmental investment variable has a close relationship with production quantity, sales, and the amount of sludge treatment variables in K company. However, all other variables including the cost of disinfection chemicals, and the expenditure of sludge treatment have no relationship with the environmental investment variable. Additionally, short-term results show that the company's environmental expenditure variable is conversely related with the environmental performance variable.
Analysis of Correlation Between Defective Number of Sewer Pipes and I/I(Infiltration/Inflow) Volume
Chang, Dae-Hwan ; Han, Ihn-Sup ; Woo, Byung-Ha ; Hong, Seong-Gin ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 321~329
I/I(Infiltration/Inflow) characteristics should be studied to achieve I/I reduction which is a main object of sewer rehabilitation. However, The scientific and practical studies which are based on actual survey within the country are not thorough going enough. The earlier studies were limited because of a short research period and specific region. Thus, In this study, a formula is deduced by intensive correlation analysis between defective number and I/I volume in sewer pipe. It can be used as preliminary data when the project established for cost-effective pipe rehabilitation. The study shows that the researched region have a faulty point at every 9.3m on average and prove correlation between defective number and I/I volume in sewer pipes. Thus, this study can improve the investigation system and estimate the volume of the pipe rehabilitation, when site investigations for rehabilitation have been conducted.
Model development for chlorine generation using electrolysis
Sohn, Jin-Sik ; Lee, Shin-Jae ; Shin, Cho-Rong ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 331~337
Electrolysis produces hypochlorous acid by using a small quantity of NaCl as electrolyte. This process maximizes the stabilization of drinking water through the control of chlorine residual concentration. This study investigated free chlorine generation by an electrolytic method using Ti/
and stainless steel. The generation of free chlorine was increased with increasing hydraulic retention time, voltage, chlorine ion concentration and the number of electrodes. However, the change of pH did not affect the generation of free chlorine. There was no significant difference on the behavior of chlorine concentration between electrolytic method and NaOCl injection. In this study, the concentration of free chlorine predicted model based on power functional model was developed various under conditions. Electrolysis free chlorine generation model can be effective tool in the estimation of free chlorine generation.
Bacterial attachment on granular activated carbon and effect of chlorine disinfection
Baek, Yung-Ae ; Joe, Woo-Hyun ; Hong, Byung-Eui ; Choi, Young-June ; Ahn, Seoung-Koo ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 339~344
The authors investigated the bacterial community attached to granular activated carbon(GAC) particles and the susceptibility of the community to chlorine disinfection. The study was carried out at the G Water Treatment Plant in Seoul, which was in full-scale operation. Bacteria attached to the surface of GAC increased gradually with treatment from 0.4
106 CFU/g. TOC removal was under 1.0 mg/L due to increased bacterial community on the surface of GAC. It was found that TOC removal was closely related with physical and biological parameters such as pore volume and the number of attached bacteria. When the washed and the attached cells were disinfected with 1.0mg/L of chlorine for 1 hour, the washed cells with chlorination could be controlled, but the number of the attached cells increased gradually. The results suggest a possibility that the treatment and disinfection barriers can be penetrated and pathogenic bacteria may break into the drinking water supplying system.
The Effect of Open Ratio of the Inlet Baffle on Hydraulic Behavior within a Rectangular Sedimentation Basin
Park, No-Suk ; Kim, Seong-Su ; Lim, Sung-Eun ; Lee, Doo-Jin ; Seo, In-Seok ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 345~352
The purpose of inlet baffle is to distribute the flow uniformly over the entire cross-sectional area of the sedimentation basin. The goal when designing this baffle is to achieve some head loss while keeping the velocity gradients through the ports equal to the velocity gradient in the end of the flocculator, so as to not break up the flocs. Sedimentation tank performance is strongly influenced by hydrodynamic and physical effects such as inlet design. This study was conducted to evaluate the effect of open ratio of the inlet baffle on hydraulic behavior within a rectangular sedimentation basin using CFD simulation and ADV technique. In order to verify the CFD simulation, we measured the factual velocity at 18 points in the full-scale sedimentation basin at Y water treatment plant. Good agreement was obtained between the CFD predictions and the experimentally measured data. From the simulation results of the existing basin with 7.4 % open ratio, it was investigated that extreme decrease in velocity occurred in the middle of basin. Since then, flow features was unstable. The region which the velocity decrease rapidly moved forward to the flow direction in proportion to the increase of inflow velocity. Also, it was investigated that the flow characteristic of 6.0 % open ratio was significantly different from 7.4 % open ratio at the same configuration condition. These results are a clear indication that inflow momentum and open ratio are the parameters affecting the characteristics of hydraulic patterns. The influence of these parameters on the sedimentation performance requires further study.
Measurements and methods for analyzing zeta potential of the external surface of hollow fiber membranes
Lee, Tae-Seop ; Lee, Sang-Youp ; Lee, Joo-Hee ; Hong, Seung-Kwan ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 353~362
A new method and equipment for measuring the zeta potential of the external surface of hollow fiber (HF) membranes is reported. An existing commercial streaming potential analyzer in conjunction with home-made test cells was used to determine the electrokinetic surface characteristics of various HF membranes. It was shown that measurements of the external surface of HF membrane using the home-made test cells designed in this study were easy and reliable. The zeta potential values were quite accurate and reproducible. By varying the physical shape of the test cells to adjust hydrodynamics inside the test cells, several upgrade versions of home-made test cells were obtained. It was shown that the zeta potential of the external surface of HF membranes was most influenced by membrane materials as well as the way of surface modification. However, the overall surface charge of tested HF membranes were much less than that of commercial polyamide thin-film-composite (TFC) reverse osmosis (RO) membranes due to the lack of surface functional groups. For the HF membranes with the same material, the effect of pore size on the zeta potential was not significant, implying the potential of accurate zeta potential measurements for various HF membranes. The results obtained in this study are expected to be useful for better understating of electrokinetic surface characteristics of the external surface of HF membranes.
Evaluation of Primary Clarifier by Wastewater TSS Characterization
Lee, Byong-Hi ;
Journal of Korean Society of Water and Wastewater, volume 23, issue 3, 2009, Pages 363~369
In order to evaluate primary clarifier performance on TSS(Total Suspended solids) removal, four different sampling sets were collected as part of this study; (1) weekly test, (2) the diurnal sampling, (3) the settling velocity distribution sampling. Primary effluent TSS(TSSPE) and non settleable TSS(TSSNON) concentrations were averaged 160 and 75.5 mg/L, respectively. These data suggest approximately 85 mg/L TSS can be removed more. Average TSSNON, TSSPE, and Dispersed TSS(DTSS) concentrations(75.5, 160, and 104 mg/L, respectively) suggest that 28.5 mg/L of TSS difference attributable to poor flocculation, whereas 56 mg/L of TSS difference attributable to poor hydraulics within primary clarifier. In this study, equations for maximum TSS removal efficiency and effluent TSS concentration were suggested and compared with experimented data.