• 상하수도학회지
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• 제22권4호
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• pp.437-444
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• 2008

Many other countries have investigated the new backwash water treatment process to save the existing water resource. There are various methods for reusing backwash water, but the membrane system has received the most interest for its efficiency. The objective of this study was to certify the application of membrane filtration system for the backwash water treatment. The experiment equipment was composed of Lab scale tubular membrane filtration system. Generally, cross-flow operation mode is used in the tubular membrane system but cross-flow operation mode demands high electric cost mainly for the pump energy. So to cut off electric cost, dead-end operation mode was used in this experiment. Filtration and bleed operation cycle was used in this membrane system. Backwash water was concentrated during the filtration process and when backwash water reached our target suspended solid concentration, it was discharged from this system. For efficient operation of filtration and bleed, mathematical matrix was drawn up and with this matrix we could simulate various sets of filtration and bleed time.

• 환경위생공학
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• 제23권4호
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• pp.13-21
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• 2008

With the rise in membrane applications, residuals management has become a growing challenge for membrane system. The primary residuals of MF/UF (microfiltration/ultrafiltration) system results from the wastes generated during backwashing. Many regulatory agencies, utilities, and water process engineers are unfamiliar with the characteristics and methods for treatment and disposal of membrane residuals. Therefore, this study was performed to investigate the backwash residuals water quality from the pressurized system with and without pre-coagulation, and to suggest approaches for the backwash residuals treatment. Pressurized MF system was installed at Guui water intake pumping station and operated with raw water taken from the Han River. We compared performances with and without the recycling backwash residuals at flux conditions, 50 LMH and 90 LMH with and without pre-treatment (coagulation). Based on the results, recycling of backwash residuals in pressurized system with pre-coagulation showed applicability of backwash residuals managements. Moreover, the recovery rate also increased up to over 99%.

• 한국물환경학회지
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• 제22권1호
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• pp.17-22
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• 2006

This study is about backwash condition and membrane fouling at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06m^3/d$. The result of the test, Backwash cycle time and duration time had a significant effect on the efficiency of system and backwash. Backwash duration time was determined to be fixed in 30 seconds for the system with more than 95% recovery rate, It needed 30 minute backwash frequency. During the continuous operation, membrane fouling was analyzed by determining the filtration resistance ($R_i$) and cake layer resistance ($R_c$). At the initial stage, filtration resistance highly influenced the fouling behavior. But after 1.5 hours, cake layer resistance became more important than filtration resistant.

• 상하수도학회지
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• 제29권2호
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• pp.251-259
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• 2015

The main objective of this research is to study feasibility for applying metal membrane to remove particles from air scouring membrane backwash water. Also, the research was conducted to investigate the influence of polyamine coagulation on floc growth in membrane backwash water as pretreatment for removal particles. From the results of experiments for evaluating the influence of polyamine coagulation on floc growth, it was investigated that particles in the rage of $2{\sim}50{\mu}m$ grew up to $30{\sim}5,000{\mu}m$. In addition, all six metal membranes showed lower removal efficiency, which was 0.87~13.89%, in the case of no polyamine coagulant. On the other hand, in the case of injecting polyamine coagulant, those did extremely high efficiency in 56~92%. From the SEM(Scanning Electron Microscope) images of filtered wiremesh and metal foam membrane, sieve effects were predominant for liquid solid separation in wiremesh and adsorption and diffusion capture effects were predominant in metal foam membrane.

• 상하수도학회지
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• 제22권1호
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• pp.87-92
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• 2008

Purposes of this study were to evaluate operational performance of submerged membrane bioreactor (MBR) combined with periodic chemical backwash. Five lab-scale submerged MBRs were performed in accordance with NaOH dose, backwash solution volume. While filtration resistance of MBR system without backwash (Control) was increased persistently from startup, those of four MBR systems (RUN 1-4) with chemical backwash were maintained at $(1.4{\pm}0.16){\times}10^{12}$, $(8.6{\pm}0.90){\times}10^{11}$, $(1.9{\pm}0.10){\times}10^{12}$, $(1.4{\pm}0.10){\times}10^{12}l/m$, respectively. Under chemical backwash condition of 0.0230 M, 375 mL, permeability of membrane was highest at flux of $30L/m^2/hr$. According to results from experiment that changing condition of dose and volume, it was estimated that effect of chemical dose acts more greatly than backwash solution volume. Because COD removal rates of all MBR systems with chemical backwash were more than 96%, it was proved that NaOH added to backwash solution did not affect microorganism.

• 상하수도학회지
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• 제22권2호
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• pp.267-274
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• 2008

This study is about efficiency of pretreatment process and operating factor to membrane process at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06{\beta}(C)/d$. The raw water used was from Nakdong stream which was characteristized by high organic matter and high turbidity. The result of the test was that coagulation is good process as to high removal rate to organic matter and turbidity but It caused problem to membrane pore blocking. This paper is to determine the membrane fouling potential under different membrane flux, backwash pressure and linear velocity. Backwash pressure and flux is important parameter on operation of membrane system. Those are directly affected on membrane system. When backwash pressure increased from 150 kPa to 200 kPa, the result showed that fouling (pressure increase rate) changed from 3.69 kPa/h to 0.93 kPa/h and the recovery rate changed from 90.7 % to 82.0 %. Linear velocity had slightly effect on fouling. Linear velocity increased from 0.2 m/s to 0.5 m/s, the corresponding pressure rate changed from 0.93 kPa/d to 0.77 kPa/d.

• 상하수도학회지
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• 제23권6호
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• pp.855-864
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• 2009

The main object of this work was to determine the influence of periodic chemical backwash on filtration resistance in membrane filtration system. In this work Hermia's models were used to investigate the fouling mechanisms involved in the microfiltration of $0.45{\mu}m$ filtered sewage feed. Batch microfiltration experiments were performed at transmembrane pressure 0.4 bar and different feed SCOD concentration (9~67 mgSCOD/L). The results showed that the best fit to experimental data corresponded to the intermediate blocking model followed by the standard and complete blocking model for all the experimental conditions tested. From the simulation results of filtration performance, it was found that in order to maintain sustainable operation of membrane filtration system, irreversible foulant component accumulated continuously on membrane surface and/or pore must be effectively removed. In addition, it was verified that periodic chemical backwash using NaOCl or NaOH effectively improved filtration performance of membrane.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 제6회 하계 Workshop (98 한국막학회, 국립환경연구원 국제 Workshop, 수자원 보전과 막분리 공정)
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• pp.155-170
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• 1998

1. The flux for hydrophilic CA membrane is higher than that for hydrophobic PES membrane at any operating conditions. The difference in bpth fluxes becomes greater as the water recovery is lower. 2. Backwash pressure should be more than twice as high as filtration pressure in order to maintain the higher flux. Backwash frequency is independent of the flux when the UF is operated under the same water recovery. 3. The relatively lower crossflow velocity of around 0.1 m/s would be appropriate because of the lower energy consumption per treated water. 4. The membrane fouling occurring at high turbidity and high concentration of organic compounds in raw water can reduce the flux and increase the removal of the organic compounds. 5. It is confirmed by the pilot plant testing that the UF by using the CA membrane module was well applicable to the drinking water treatment.

• 상하수도학회지
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• 제30권3호
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• pp.335-341
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• 2016

Various studies have forwarded an outstanding wastewater effluent treatment systems toward securing sustainable supply of water sources. In this paper, a broad overview of the performance of MF membrane as pretreatment option for wastewater reuse will be presented based on the literature survey and experiments conducted over the wastewater reuse pilot plant. The pilot plant was operated with a continuous data acquisition for about 300days under various chemical enhanced backwash (CEB) system with subsequent treated water quality analysis. Accordingly, assessment of the effluent revealed that the pretreated water is suitable enough to be used as an input for Reverse Osmosis (RO) unit and significant effect of CEB and concentration of NaOCl is also conceived from the analysis. Moreover, it's also observed that the application of various CEB condition over long operational hours induced a constant declination of overall performance of MF membrane.

• 상하수도학회지
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• 제28권4호
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• pp.479-489
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• 2014

Membrane backwashing waste shows seasonally different characteristics and it has bad settleability differently from general backwashing waste in water treatment plant. When chemicals was injected to membrane backwashing waste, the settleability was better than chemicals was not injected. However, when settled lower sludge was not discharged, flowing sludge continuously was concentrated over a certain surface and floatation penomena occurred according to flowing velocity. When the lower sludge was discharged continuously in the thickener to prevent floatation penomena of turbidity materials, the depth of sludge surface was the least and the settleability increased.