• Membrane and Water Treatment
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• v.14 no.4
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• pp.175-180
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• 2023

Mixed matrix membranes (MMMs) can be a promising alternative for the solution of dye removal from coloured effluents. Polymeric membranes are widely used due to their good film-forming ability, flexibility, separation properties, and cost. However, they have low mechanical, chemical, and thermal resistances. Moreover, the fouling of polymeric membranes is high because of their hydrophobic nature. Hence, there is an increasing interest in organic-inorganic hybrid membranes as a new-generation membrane material. It has been shown that carbon nanotubes have the potential to increase the material properties of polymers with their low density, high strength, hardness, and exceptional aspect ratio. In this work, carbon nanotubes blended MMMs were prepared and methyl orange removal efficiency of them was investigated. Compared to the bare membranes, MMMs showed not only increased hydrophilicity, water content, and pure water flux but also increased methyl orange rejection and flux recovery

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.25-30
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• 2005

In order to decrease the high costs of membrane process, we have tried to develop two alternatives to membrane; a cartridge type filter and a metal membrane were tested for the high permeation flux with low cost and low energy. This research mainly focused on three points; 1) operation with high permeation flux by using of a cartridge type filter and a metal membrane, 2) removals of the filterable organic materials (FOC) by pretreatments for the membrane fouling control, and 3) advanced wastewater treatment by SMBR process with intermittent aeration and high MLSS. An Intermittently aerated membrane bioreactor using a submerged micro filter (cartridge type) was applied in laboratory scale for the advanced wastewater treatment. To minimize membrane fouling, intermittent aeration was applied inside of the filter with $3.0kg_f/cm^2$. The experiments was conducted for 6 months with three different HRTs (8, 10, 12 hr) and high MLSS of 6,000 and 10,000mg/L. The filtration process could be operated up to 50 days with permeation flux of 500LMH. Regardless of the operating conditions, more than 95% of COD, BOD and SS were removed. Fast and complete nitrification was accomplished, and denitrification was appeared to be the rate-limiting step. More than 75% T-N could be removed due to the endogenous denitrification. T-P removal efficiency was increased to 80% under the condition of MLSS 10,000mg/L.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.151-160
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• 2014

Capacitive deionization(CDI) has many advantages over other desalination technologies due to its low energy consumption, less environmental pollution and relative low fouling potential. The objectives of this study are evaluate the performance of CDI which can be used for dissolved salts removal from sewage. To identify ion selectivity of nitrate and phosphate in multiionic solutions and adsorption/desorption performance related to applied potential, a series of laboratory scale experiments were conducted using a CDI unit cell with activated carbon electrodes. The CDI process was able to achieve more than 75 % TDS and $NO_3{^-}$, $NH_4{^+}$ removals, while phosphate removal was 60.8 % and is inversely related in initial TDS and $HCO_3{^-}$ concentration. In continuous operation, increasing the inner cell pressure and reduction of TDS removal ability were investigated which are caused by inorganic scaling and biofouling. However a relative mild cleaning solution(5 % of citric acid for calcium scaling and 500 mg/L of NaOCl for organic fouling) restored the electrochemical adsorption capacity of the CDI unit to its initial level.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.429-436
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• 2008

Membrane system has been increasingly considered as a safe and cost-effective water treatment process especially in case of small scale water works. This research is a basis of membrane application in water works through a long period test with obtaining operation skills and evaluation of water quality and cost competitiveness. For the research, the UF membrane system was installed in small water treatment plant that uses river-bed water as raw water. The system was consisted of 2 stage membrane and operated in constant flow mode (Flux: 1.5, 1.0, 0.9, 0.6). In each different flux condition, TMP trends were showed better results at lower flux condition. And through the high flux condition test, it is certified that membrane system could deal with breakdown of one stage. Water quality of permeate was satisfied the water quality standards especially turbidity. To know what mainly causes fouling on membrane, the test by membrane with several cleaning agents and EDX analysis have done in lab. Through the tests, ferrous concentration in raw water, backwashing water and membrane surface etc. was high and it causes fouling inside and outside of membrane. So acid cleaning using organic acid such as oxalic acid is necessary in Chemical in Place (CIP). At the economical aspect the electrical cost of membrane system is higher than that of slow sand filtration but labor cost can be reduced by automation. However, the use of labor should be determined considering effectiveness and stability of operation. Because during the operation, there are several breakdown such as electrical shock by lightning, water drop in summer, etc.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.837-843
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• 2005

Coagulation influence was evaluated as the pretreatment for ultrafiltration. Coagulation was expected to improve water quality, reduce membrane fouling and increase backwash effect. Continuous operation of UF was employed in order to investigate the influence of coagulation. Alum, PACS and Ferric chloride were used as coagulants separately. From the result of the research, coagulation can improve the treated water quality greatly. Organic removal was increased more than turbidity and showed an improvement of 30.6% at most. All three coagulants presented conspicuous reduction of membrane fouling, among which PACS was the most effective with long term run. Backwash effect differed with different coagulants while Ferric chloride turned out to be the most effective one. The optimum dosage of coagulant resulted in the highest backwash efficiency.

• Membrane Journal
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• v.22 no.6
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• pp.415-423
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• 2012

For hybrid water treatment of carbon fiber ultrafiltration and photocatalyst, we used the hybrid module that was composed of photocatalyst packing between tubular membrane outside and module inside. Photocatalyst was PP (polypropylene) bead coated with $TiO_2$ powder by CVD (chemical vapor deposition) process. Water back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling for modified solution, which was prepared with humic acid and kaolin. Resistance of membrane fouling ($R_f$) decreased as humic acid concentration changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L, which was the same with the previous results. Then, treatment efficiencies of turbidity and humic acid were above 98.9% and 88.7%, respectively, those did not depend on the humic acid concentration. However, the treatment efficiency of humic acid increased a little as the humic acid concentration increased in the previous results.

• 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.

• Membrane Journal
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• v.11 no.4
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• pp.179-189
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• 2001

Effect of ozonation on permeate flux was studied by using polysulfone ultrafiltration membrane. The filtration was first carried out by permeating phenol solutions under 3$kg_{f}$/$cm^2$ until steady-state flux was obtained. Then, the ozone of concentration range between 10 and 45 mg/1.min was ozonated in water for reducing the fouling on the UF membrane. Treatment of chemical wastewater by combined ozone and membrane filtration methods was also investigated for the final purpose. The Fenton method assisted by chemical coagulation was employed as a prtreatment method and found to be highly efficient in removing a large amount of organic compounds. And it was found that the ozonation made the permeate flux enhance in the phenol solution and phenolic-chemical wastewaster by 10% and oxidation by ozone and hydrogen peroxide was more effective. Evidence was presented that TMP decreased in more ozone concentrated water and it was found that the ozone-mediated membrane would have a limited role to prevent the membrane fouling rather than to eliminate fully.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.959-970
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• 2000

A laboratory-scale experiment was conducted to investigate the effect of soluble microbial products(SMP) on permeate flux in the submerged membrane separation activated sludge process. Continuous and batch filtration test were operated to understand mechanism of relationship between membrane fouling and SMP. Synthetic wastewater(phenol) was used as a carbon source. Hydraulic retention time(HRT) and mixed-liquor volatile suspended solids(MLVSS) of the reactor were kept at 12 hours and 9.000mg VSS/L, respectively. Batch filtration tests ($J_{60}/J_o$) using the mixed liquor from reactor showed that the increase of accumulated SMP concentration in the reactor caused to the decreasing permeate flux and the increasing of the adhesion matters which form cake and gel layer. The resistance value of cake layer was measured $2.9{\times}10^{10}{\sim}4.0{\times}10^{10}(1/m)$, this value showed more significant effect on flux drop than that of among other resistance layers. Batch phenol-degradation experiment was conducted to observe SMP type expected $SMP_{nd}$ and $SMP_{e}$ (SMP resulted from endogenous cell decomposition), these are non-biodegradable high molecular weight organic matter and playa significant role in permeate flux drop. Also, SMP concentration was accumulated as increased of HRT against flux drop.

• Membrane Journal
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• v.22 no.5
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• pp.359-368
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• 2012

For hybrid water treatment of high turbidity water, we used the hybrid module that was composed of photocatalyst packing between tubular membrane outside and module inside. Photocatalyst was PP (polypropylene) bead coated with $TiO_2$ powder by CVD (chemical vapor deposition) process. Water back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling for modified solution was prepared with humic acid and kaolin. Resistance of membrane fouling ($R_f$) decreased as humic acid concentration changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L, which was the same with the previous results. Then, treatment efficiencies of turbidity and humic acid were above 98.9% and 88.7%, respectively. As results of treatment portions of UF, UF + $TiO_2$, and UF + $TiO_2$ + UV processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of humic acid by adsorption and photo-oxidation were 2.5% and 12.3%, respectively. Compared with the previous results, treatment portions of humic acid by adsorption and photo-oxidation were different depending on membrane material and pore size. As simplified the process, the membrane fouling resistance after 180 minutes' operation ($R_{f,180}$) increased and the final permeate flux decreased a little.