• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1060-1067
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• 2006

This study was undertaken to determine the effect of reservoirs on water quality and the distribution of pathogenic and indicator bacteria in a drinking water distribution system (total length 14km). Raw water, disinfected water, and water samples from the distribution system were subjected to physicochemical and microbiological analyses. Most factors encountered at each season included residual chloride, nitrate, turbidity, and phosphorus for heterotrophic bacterial distribution, and hardness, heterotrophic bacteria, sampling site, and DOC (dissolved organic carbon) for bacteria on selective media. No Salmonella or Shigella spp. were detected, but many colonies of opportunistic pathogens were found. Comparing tap water samples taken at similar distances from the water treatment plant, samples that had passed through a reservoir had a higher concentration of heterotrophic bacteria, and a higher rate of colony formation with 10 times as many bacteria on selective media. Based on the results with m-Endo agar, the water in reservoirs appeared safe; however, coliforms and opportunistic pathogenic bacteria such as Pseudomonas aeruginosa were identified on other selective media. This study illustrates that storage reservoirs in the drinking water distribution system have low microbiological water quality by opportunistic pathogens, and therefore, water quality must be controlled.

• Journal of Korean Society on Water Environment
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• v.35 no.5
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• pp.409-417
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• 2019

In this study, a $480m^3/day$ pilot device was constructed through laboratory experiments based on the Ministry of Environment manual. The purpose of this study was to analyze the characteristics of CSO treatment and backwashing characteristics by applying the pilot device to the field. The purpose of this study was to acquire the basic data necessary for the design and operation management of the real scale filtration type non-point pollution control system. The filtration was conducted while maintaining the linear velocity of 20m/hour. The CSO treatment efficiencies of the pilot devices were 0.4-76.1%(mean 49.0 %), SS 51.4-91.6%(mean 77.8%), COD 22.2-59.4% (mean 38.3%) and TP 14.5-52.6%(mean 38.1%),respectively. The correlation coefficient between SS and the turbidity of influent water was 0.90, higher than that of CSO. To operate the treatment system effectively, the turbidity can be easily measured in real time as the monitoring item is the most appropriate because SS is the main target substance of the non-point source. As a result of analyzing the adsorbent treatment characteristics of PP filter material applied to this pilot device, the average particle diameter range of influent was $4.6-40.1{\mu}m$(mean $21.2{\mu}m$) and the treated water was $0.9-24.5{\mu}m$(mean $6.4{\mu}m$), respectively. Particles of approximately 10m or less are leached out, and so it is necessary to compensate for the raw water containing micro particulate matter.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.07a
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• pp.57-68
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• 2004

A demonstrative operation of a membrane system with its caparity of 3,600m$^3$/d was carried out using reservoir water as raw water for the application of membrane filtration system to drinking water treatment. The operation was undertaken at a constant flux of 0.9 m$^3$/m$^2$/d for three months. Backwashing with NaClO of 3 ppm was allowed for 30 seconds every 20 minutes of filtration. Physical cleaning was introduced after 69 times of filtration/backwashing cycle with air-scrubbing and backwashing for 1 minute, and flushing for 2 minutes. In this study, water treatment performance was investigated compared with the existing rapid sand filtration process. The membrane system was operated with no significant problems during the test period. Higher water quality was obtained in the membrane filtration than in the rapid sand filtration in terms of particulate matters such as turbidity and microbes. Although the finished water of the membrane filtration contained slightly higher concentration in dissolved matters than that of the conventional one, it met the drinking water standard. The demonstrative operation showed that membrane filtration has a reliability in drinking water treatment. Researches should be needed on cost analysis through long-term operation and optimization of operation condition for further application.

• Membrane Journal
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• v.20 no.2
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• pp.97-105
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• 2010

This study was to evaluate the performance of the Double stage Pore controllable fiber (DP) filter system as the pre-treatment of the RO membrane. The evaluation for the pre-treatment filter was performed through the indirect method, SDI (Silt Density Index) measurement of the filtrate. This study was done during Jan. 3 of 2009 to Dec. 3 of 2009 at OO Water Treatment Plant that was suppling industrial water to plants, and the raw water was contaminated lake water and it was fed to the system after clarification with coagulation. The average turbidity of the feed water and that of the filtrate was 0.79 NTU (0.28~4.01 NTU), and 0.16 NTU (0.04~0.50) respectively. And so the average turbidity removal efficiency was 77%. The filtrate flow rate and the backwash water flow rate was about 230 $m^3$/day and about 8.7 $m^3$/day respectively, and so the backwash rate was 3.8%. The data for some samples were obtained after a few days storage, and it caused the higher turbidity and SDI15 as the storage time was increased. But average SDI value of the filtrate was 3.6 (2.26~5.00) which was lower than minimum value required by the RO membrane manufacturer as the RO feed water to guarantee the life time of the RO membrane. So, the DP filter system was enough for the application as the pre-treatment of the RO membrane.

• 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 Water and Wastewater
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• v.27 no.1
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• pp.101-112
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• 2013

Integrated process with coagulation and microfiltration as an advanced water treatment has been expanded its application in recent years due to its superb removal of particles and natural organic matter. In usual, effectiveness of coagulation sometimes determines performance of the whole system. Several new polymeric coagulants introduced to water utilities for better efficiency were studied in this paper. Three polymeric coagulants (i.e., PACl, PACs, and PAHCs) along with alum were evaluated for removal of natural organic matter, especially for reduction of trihalomethane formation potential, for which regulation has become stringent. Turbidity removal was closely related to pH variation showing the reduced turbidity removal by PACs due to the decreases in the pH of supernants at high doses. The four coagulants showed different organic matter removal during coagulation and affected the removal in microfiltration. For instance, DOC concentration was not reduced by microfiltration when PAHCs were used however 10 % of DOC removal was observed by microfiltration with alum coagulation. Coagulation pretreatment also impacted the THM removals, i.e., approximately 30 % of THMs and 13 % of DOC was removed by microfiltration only, but 40 to 67 % of THMs and 30 % of DOC was removed by the integrated process. Strategies on selection of coagulants are needed depending on characteristics of target pollutants in raw waters.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.99-107
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• 2018

This research has developed a high temperature steam cleaning technology using a ceramic membrane with durability against temperature and pressure conditions. In steam cleaning, steam of $120^{\circ}C$ is injected into the ceramic membrane to induce pyrolysis by the endothermic reaction to remove fouling from the membrane. The water quality of raw water was adjusted to turbidity 10, 25 NTU and DOC 2.5 mg/L, and the membrane was uniformly fouled by constant pressure operation at 100, 200, and 300 kPa. Physical backwashing was performed with water and air at a pressure of 500 kPa and steam at $120^{\circ}C$ was injected for 0 to 5 minutes. As the turbidity concentration and the operating pressure increased, the flux decreased by 0.7 to 14.4%. It is confirmed that 10.7 to 53.8% recovery is possible than physical cleaning at the injection of steam for 3 minutes, so it is considered that the steam cleaning of the ceramic membrane is effective. Compared with CEB after NaOCl (300 mg/L) filtration at 25 NTU and 300 kPa of turbidity, the steam cleaning result for 3 minutes was similar to 46.7% of CEB for 3 hours. It has been confirmed that steam cleaning is suitable for a ceramic membrane having excellent heat resistance against high temperature. It was considered to have better cleaning efficiency as compared with general physical backwashing.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.17-22
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• 2013

In this study, a pH control method by carbon dioxide ($CO_2$) was applied to coagulation process in water treatment plant (WTP) to investigate the coagulation efficiency and residual dissolved aluminum when high pH raw water is flowing into the plant during algal blooming. Existing coagulant dose (1 mg/L in raw water) resulted in the pH reduction of 0.0384 by LAS, 0.0254 by PAC, 0.0201 by A-PAC, and 0.0135 by PACS2, respectively. And then the concentration of dissolved aluminum was 0.02 mg/L at pH 7.44, 0.07 mg/L at pH 7.96, 0.12 mg/L at pH 8.16, 0.39 mg/L at pH 8.38 showing the concentration increase with pH in the coagulation process. It was noteworthy that rapid increase was observed at pH above 8.0 next the rapid mixing. Therefore it is necessarily required to control pH below 7.8 in the coagulation process in order to meet drinking water quality standard of aluminum for high pH raw water into WTP, $CO_2$ injection could control pH successfully at about 7.3 even for the raw water of high pH above 8.0. In addition it was found that the pH control by $CO_2$ injection was significantly effective for coagulation in terms of turbidity removal, coagulant dosage, and residual dissolved aluminum concentration.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.58-63
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• 2009

Dissolved air flotation (DAF) process is generally considered more effective than sedimentation process in raw water containing algae, humus materials, and low density particles. This study presents the treatment efficiencies by the coagulation and flocculation conditions at a drinking water treatment plant using a laboratory tester and the full scale DAF pump system. The full scale DAF pump system (F-DAF) in this study had a capacity of 5,000 $m^3$/d and a hydraulic surface loading of 10 m/hr. F-DAF in D drinking water treatment plant was continuously operated to determine the operational performance and pretreatment (mixing and coagulation) conditions. Results in the laboratory experiment showed that the optimum coagulant (PSO-M) doses required to 2.7~4.5 mL/$m^3$/NTU with raw water turbidity from 13.8 NTU to 56.3 NTU. F-DAF in the optimum coagulant dosage could be operated in effluent turbidity of 1 NTU or below for a month.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.551-556
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• 2004

Coagulation process is one of the most important processes in water treatment procedures for stable and economical operation, and coagulant dosing of this process for most plants is generally determined by the jar test. However, this method does not only take a long time to analyze and get the result but also has difficulties in applying to automatic control. This paper shows the feasibility of applying neural network to control the coagulant dosing automatically in water treatment plant. To be specific, the predicted results of the neural network model is shown to be similar to that of jar test. The input variables for learning the neural network are turbidity, water temperature, pH, and alkalinity. Combining the neural network and SCD(Streaming Current Detector) for feedforward and feedback control of injecting coagulant, a rapid change of the raw water quality can be accommodated.