• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.15-24
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• 2010

Coagulation can be used for pretreatment of NF membrane filtration. Foulants such as organic matter and particulate can be removed effectively with the process while high flux recovery is maintained. Recently various types of polyaluminium coagulants including polyaluminium chloride(PAC) are commercially available for water treatment. This study examines effects of polymeric Al and hydrolysis products of PAC on nanofiltration membrane performance. Dominant hydrolysis products were polymeric Al, $Al(OH)_3$, and ${Al(OH)_4}^{-1}$ at acidic, neutral, and alkaline pH conditions, respectively. Under acidic pH condition, flux decline was increased with increasing PAC concentrations, possibly due to polymeric Al adsorption on membrane pore and/or surfaces. For neutral and alkaline pH conditions, little flux decline was observed with increasing PAC concentrations except the highest ${Al(OH)_4}^{-1}$ concentration, with which rapid flux decline was shown. Removal of ionic matters was also varied with pH conditions in this study. Especially, conductivity removal was substantially low and $Ca^{2+}$ concentration in the permeate was quite high at neutral pH condition.

• Membrane Journal
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• v.11 no.4
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• pp.152-160
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• 2001

The pretreatment for COD removal of acrylic wastewater and separation characteristics of ultrafiltration hollow fiber type module and reverse osmosis spiral wound type module with the variation of applied pressure and temperature were discussed. Thc optimum washing time of membranes was decided with long team operation and the degree of fouling was discussed with operating time. Permeate flux was decreased rapidly at 14 hrs and that of reverse osmosis membrane was indicated similarly. CaO find sand filter for the first step, neutralization process with treated acrylic wastewater as the second step, UF/RO processes were used as final strep. It was shown treat COD and TDS were below allowable discharge value with the result.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.456-461
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• 2017

In this study, nano fibers with various physical properties were materialized by using a variety of polymers [PAN (Polyacrylonitrile), PU (Polyuretane), PSU (Polysulfone)] which are raw materials of dope solution manufactured for electrospinning and solvents [NMP (N-methyl-2 pyrrolidone), DMF (Dimethylformamide)] and evaluated characteristics of their flux and SS (Suspended Solids) separation and then ascertained application of manufactured fibers as separation membrane for water treatment. In this study, analysis of surface of manufactured material was carried out through SEM analysis to ascertain the cause of flux and SS separation performance by checking diameter, uniformity and straightness of fiber. If additive is used in manufacturing nano fiber water treatment separation membrane, it is expected to solve problems such as membrane fouling and mechanical strength and to be used as basic factor for manufacturing separation membrane with catalyst function added.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.143-155
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• 2013

Four membranes were used to separate Chlorella sp. from their culture medium in cross-flow microfiltration (MF) experiments: cellulose acetate (CA), cellulose nitrate (CN), polypropylene (PP) and polyvinylidenefluoride (PVDF). It was found that the hydrophilic CA and CN membranes with a pore size of 1.2 ${\mu}m$ exhibited the best performances among all the membranes in terms of permeation flux. The hydrophobicity of each membrane material was determined by measuring the angle between the water (liquid) and membrane (solid). Contact angle measurements showed that deionized (DI) water had almost adsorbed onto the surfaces of the CA and CN membranes, which gave $0.00^{\circ}$ contact angle values. The PP and PVDF membranes were more hydrophobic, giving contact angle values of $95.97^{\circ}$ and $126.63^{\circ}$, respectively. Although the pure water flux increased with increasing pore diameter (0.8 < 1.2 < 3.0 ${\mu}m$) in hydrophilic CA and CN membranes, the best performance in term of filtration rate for filtering a microalgae suspension was attained by membranes with a pore size of 1.2 ${\mu}m$. The fouled membrane pore sizes and pore blocking were inspected using a scanning electron microscope (SEM). MF with large pore diameters was more sensitive to fouling that contributed to intermediate blocking, where the size of the membrane pores is almost equivalent to that of cells.

• Membrane Journal
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• v.18 no.1
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• pp.1-6
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• 2008

After membrane fouling factors in acrylic wastewater were minimized by pretreatment process accompanied with coagulation-filtration-neutralization, it was utilized in UF/RO process. After composing of ultrafiltration and reverse osmosis module set according to types and kinds of membrane, the separation characteristics were examined with the variation temperature and pressure using pretreated acrylic wastewater by membrane module sets. It was found that permeate flux of UF module in module set 4 was about two${\sim}$three times larger than that of UF module in module set 1. Final quantity of permeate from the module set 2 and module set 3 combined with tubular module was shown very good result. It was shown that the removal efficiency of TDS, T-N and COD was very low and was not dependent on the variation of temperature and pressure in all UF modules. The removal efficiency of TDS, T-N and COD was very excellent in RO module. Final water quality of acrylic wastewater was satisfied with effluent allowances limit and membrane module sets were ascertained to reuse wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.391-399
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• 2016

In this study, carbon dioxide ($CO_2$) was used as an inhibitor of scale production on the surface of RO membrane. In order to compare the effects of $CO_2$ injection on scale production, four RO modules: 1) without $CO_2$ injection and anti-scalant (RO module #1), 2) with only $CO_2$ injection (RO module #2), 3) with only anti-scalant (RO module #3), 4) with both $CO_2$ injection and anti-scalant (RO module #4), were operated for 60 days under constant flux mode. The trans-membrane pressure (TMP) was observed to decrease significantly in RO modules with $CO_2$ injection as compared with the other RO modules. When the feed water pH was controlled at 5.0 by injecting $CO_2$, the maximum TMP in RO modules #2 and #4 was founded to decrease by 42 and 40%, respectively. Moreover, the $Ca^{2+}$ concentration in the concentrate was 20mg/L lower in RO modules without $CO_2$ injection which is attributed to the scale formation on the surface of the RO membranes. The SEM-EDS analysis further showed a serious fouled RO membrane surface in RO modules #1 and #3.

• Membrane Journal
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• v.15 no.1
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• pp.70-83
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• 2005

By supplying air intermittently in various mode, the effects of oxic/anoxic time ratio and air scrubbing in aeration condition on the membrane flux and permeability were investigated. When suction pump stops, vacuum pressure remains inside the suction pump. Therefore, the effect of remaining vacuum pressure in the suction pump on fouling of membrane was investigated. The effect of EPS (Extra cellular Polymeric Substance) which is generated due to the long SRT and high concentration of MLSS and the dose of coagulant on the membrane were also investigated. The suitable oxic/anoxic time ratio for the best removal efficiency of organic matter and nitrogenous matter was 40 minutes (Oxic) : 20 minutes (Anoxic). At this time ratio, alum was dosed into the aeration tank. The result of dosing alum was that the concentration of alum solution might affect nitrification and denitrification. To remove 1 mg/L of phosphorus in MBR process, it needs 0.75 mg/L of alum solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.224-231
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• 2019

Recently, the pollution of groundwater has become serious. In particular, the contamination of groundwater near livestock farms is becoming increasingly severe and it is difficult to drink with drinking water. In this paper, a groundwater purifier apparatus that can be installed in a community well was designed. The designed groundwater purifier apparatus enables a RO membrane filter and UV sterilization to remove pollutants, such as heavy metals, bacteria, and organic compounds. In addition, electrical conductivity, pressure, and flow sensors were added for remote monitoring. Remote monitoring of the system can determine the level of fouling and contamination of RO membrane filters through pressure and flow sensor data, and can record changes in the contamination and condition of groundwater through the electrical conductivity of the feed water. The designed groundwater purifier apparatus was installed at a farmhouse and remote monitoring. The result after 15 days of operating a groundwater purifier apparatus and analyzing the monitoring data revealed an average permeate water flow rate of 2.67L/min and an average water pressure of 7.09kgf/㎠, indicating that the RO Membrane filtered without fouling and clogging. The average electrical conductivity was 796.6 S/㎠ of the feed water and 55.6 S/㎠ of permeate water, which is similar to that of general tap water. Through this, it was confirmed that no pollutant occurred in the surroundings. Therefore, the designed groundwater purifier apparatus can confirm the replacement time of the RO membrane filter in advance through remote monitoring, and check the pollution state of the groundwater.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.677-685
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• 2011

The reverse osmosis membrane processes have several operational problems. Fouling by inorganic scale occurs on membrane surface due to increases in concentrations over solubility by retaining ions on feed side of the membrane. Inorganic scales could be controlled by antiscalants or acid addition. In this study, three antiscalants having different characteristics were selected and evaluated on efficiency of $CaCO_3$ scale control. The $CaCO_3$ scale was inhibited by the antiscalants : 0.4 mg/L for SHMP, 0.6 mg/L for Spectra Guard, and 3 mg/L for Flocon 150 N. Increasing concentration factors of simulated sea water resulted in increases in antiscalant doses for the scale control. The increases in doses were positively proportional to the concentrate factors used in this study. Spectra Guard, one of the polyacrylate type antiscalants, was the most effective to control $CaCO_3$ scale. The antiscalants with the different scale inhibition time and doses implied the different control mechanisms.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.458-464
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• 1999

The value of lysozyme as a natural food preservative is continuously increased due to its unique antimicrobial activity. To determine the optimum separation concentration among the various hen egg white protein (HEWP) concentrations (0.25, 0.5, 1.0, w/v), protein concentrations, lysozyme concentrations, specific activities (SA), and purification factors of prefiltered solution (PFS) and PM30 permeate solution (PMS) were compared. The purity of lysozyme separated at each step was analyzed and confirmed by gel permeation chromatography and electrophoresis. The fouling deposits on membrane were observed by SEM. The non-enzymatic proteins were removed over 99% by ultrafiltration (UF). The increased feed concentration did not contribute to the increase of SA. SA of PMS was 18 to 31 times higher than that of PFS. The optimum feed concentration was decided as 0.25% based on SA and purification factor. The non-enzymatic region of gel chromatogram was proved to be ovalbumin. The thickness of deposit on the UF membrane was approximately $0.9{\mu}m$ and removed by cleaning with 0.1 N NaOH. Therefore, UF using PM30 membrane was very effective to separate the antimicrobial lysozyme from various HEWPs.