• Membrane and Water Treatment
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• v.9 no.1
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• pp.53-62
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• 2018

In this study, vacuum membrane distillation (VMD) was used to treat high-salinity wastewater (concentration about 17%) discharged by chlor-alkali plant after resin regeneration. The feasibility of VMD for the treatment of real saline wastewater by using Polyvinylidene fluoride (PVDF) microporous plate membrane with a pore diameter of $0.2{\mu}m$ was investigated. The effects of critical operating parameters such as feed temperature, velocity, vacuum degree and concentration on the permeate water flux were analyzed. Numerical simulation was used to predict the flux and the obtained results were in good agreement with the experimental data. The results showed that an increase in the operating conditions could greatly promote the permeate water flux which in turn decreased with an increase in the concentration. When the concentration varied from 17 to 25%, the permeate water flux dropped marginally with time indicating that the concentration was not sensitive to the decrease in permeate water flux. The permeate water flux decreased sharply until zero due to the membrane fouling resistance as the concentration varied from 25 to 26%. However, the conductivity of the produced water was well maintained and the average value was measured to be $4.98{\mu}s/cm$. Furthermore, a salt rejection of more than 99.99% was achieved. Overall, the outcome of this investigation clearly indicates that VMD has the potential for treating high-salinity wastewater.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.321-330
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• 2019

The objective of this study was to examine the recovery of the power plant cooling tower blowdown water (CTBD) by membrane distillation. The experiments were carried out using a flat plate poly vinylidene fluoride (PVDF) membrane with a pore diameter of $0.22{\mu}m$ by a direct contact membrane distillation unit (DCMD). The effects of operating parameters such as transmembrane temperature difference (${\Delta}T$), circulation rate and operating time on permeate flux and membrane fouling have been investigated. The results indicated that permeate flux increased with increasing ${\Delta}T$ and circulation rate. Whereas maximum permeate flux was determined as $47.4L/m^2{\cdot}h$ at ${\Delta}T$ of $50^{\circ}C$ for all short term experiments, minimum permeate flux was determined as $7.7L/m^2{\cdot}h$ at ${\Delta}T$ of $20^{\circ}C$. While $40^{\circ}C$ was determined as the optimum ${\Delta}T$ in long term experiments. Inorganic and non-volatile substances caused fouling in the membranes.

• Membrane Journal
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• v.19 no.3
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• pp.194-202
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• 2009

In this study periodic water-back-flushing using permeate water was performed to minimize membrane fouling and to enhance permeate flux in advanced water treatment by tubular ceramic ultrafiltration membrane for Gongji stream in Chuncheon city. The back-flushing period (FT, filtration time) 2 min with periodic water-back-flushing of 15 sec showed the highest value of dimensionless permeate flux (permeate flux vs. initial permeate flux), and the lowest value of resistance of membrane fouling. Also in the results of BT effect at fixed FT 10 min, BT (back-flushing time) 20 sec showed the lowest value of resistance of membrane fouling and the highest value of dimensionless permeate flux, and we could be obtained the highest total permeate volume of 107.3 L. Consequently FT 10 min and BT 20 sec could be the optimal condition in Gongji stream water treatment, which was the exactly same results of our previous tubular alumina microfiltration. Then the average rejection rates of pollutants by our tubular ceramic UF system were 97.0% for turbidity, 32.1 % for chemical oxygen demand by manganese method, 28.8% for ammoniac nitrogen and 54.4% for T-P.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.212-219
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• 2018

Perovskite type ceramic membranes which exhibit dual ion conduction (proton and oxygen ion conduction) can permeate water and can aid solving operational problems such as temperature gradient and carbon deposition associated with a working solid oxide fuel cell. From this point of view, it is crucial to reveal water transport mechanism and especially the nature of the surface sites that is necessary for water incorporation and evolution. $BaCe_{0.8}Y_{0.2}O_{3-{\alpha}}$ (BCY20) was used as a model proton and oxygen ion conducting membrane in this work. Four different catalytically modified membrane configurations were used for the investigations and water flux was measured as a function of temperature. In addition, CO was introduced to the permeate side in order to test the stability of membrane against water and $CO/CO_2$ and post operation analysis of used membranes were carried out. The results revealed that water incorporation occurs on any exposed electrolyte surface. However, the magnitude of water permeation changes depending on which membrane surface is catalytically modified. The platinum increases the water flux on the feed side whilst it decreases the flux on the permeate side. Water flux measurements suggest that platinum can block water permeation on the permeate side by reducing the access to the lattice oxygen in the surface layer.

• Korean Membrane Journal
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• v.11 no.1
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• pp.15-20
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• 2009

The periodic water-back-flushing using permeate water was performed to minimize membrane fouling and to enhance permeate flux in tubular ceramic ultrafiltration (UF) system for Gongji stream water treatment in Chuncheon city. The filtration time (FT), which was the water-back-flushing period, 2 min with periodic 15 sec water-back-flushing showed the highest value of dimensionless permeate flux ($J/J_o$), and the lowest value of resistance of membrane fouling ($R_f$), and we acquired the highest total permeate volume ($V_T$) of 6.35 L. Consequently FT 2 min at back-flushing time (BT) 15 sec could be the optimal condition in advanced UF water treatment of Gongji stream. Then the average rejection rates of pollutants by our tubular ceramic UF system were 99.4% for Turbidity, 31.8% for $COD_{Mn}$, 22.6% for $NH_3$-N and 65.9% for T-P.

• Membrane and Water Treatment
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• v.3 no.3
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• pp.141-149
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• 2012

The aeration provided in a Submerged Membrane Bioreactor (SMBR) improves membrane filtration by creating turbulence on the membrane surface and reducing membrane resistance. However, conventional hollow fiber membrane modules are generally packed in a vertical orientation which limits membrane scouring efficiency, especially when aeration is provided in the axial direction. In the present research, 3 innovative hollow-fiber membrane modules, each with a different membrane orientation, were developed to improve membrane scouring efficiency and enhance permeate flux. Pilot testing was performed to investigate the permeate flux versus time relationship over a 7-day period under different intermittent modes. The results indicated that the best module experienced an overall permeate flux decline of 3.3% after 7 days; the other two modules declined by 13.3% and 18.3%. The lower percentage of permeate flux decline indicated that permeate productivity could be sustained for a longer period of time. As a result, the operational costs associated with membrane cleaning and membrane replacement could be reduced over the lifespan of the module.

• Membrane and Water Treatment
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• v.12 no.2
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• pp.65-73
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• 2021

Sponge ball cleaning can generate an abrasion effect, which leads to an attractive increasing in both permeate flux and membrane rejection. The aim of this study was to investigate the influence of the daily sponge ball cleaning (SBC) on the performance of different UF cross-flow membrane modules integrated with a bioreactor. Two 1"-membrane modules and one 1/2"-membrane module were tested. The parameters measured and controlled are temperature, pH, viscosity, particle size, dissolved organic carbon (DOC), total suspended solids (TSS), and permeate flux. The permeate flux could be improved by 60%, for some modules, after 11 days of daily sponge ball cleaning at a transmembrane pressure of 350 kPa and a flow velocity of 4 m/s. Rejection values of all tested modules were improved by 10%. The highest permeate flux of 195 L/㎡.h was achieved using a 1"-membrane module with the aid of its negatively charged membrane material and the daily sponge ball cleaning. In addition, the enhancement in the permeate flux caused by daily sponge ball cleaning improved the energy specific demand for all tested modules. The negatively charged membrane showed the lowest energy specific demand of 1.31 kWh/㎥ in combination with the highest flux, which is a very competitive result.

• Membrane Journal
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• v.12 no.4
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• pp.216-225
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• 2002

Experimental study on the crossflow electro-microfi1tation of simulated oil emulsion waste water was carried out with polypropylene microfiltration membrane to evaluate the applicability of electrofiltration process in the treatment of oily waste water generated from many industries including nuclear field. The effects of electric field strength transmembrane pressure, crossflow velocity, and oil emulsion concentration on the permeate flux were investigated. In electro-microfiltration process using the external electric field, significant enhancement of permeate flux was achieved by diminishing membrane fouling and it was shown that considerable permeate flux can be maintained for long-term operation compared with conventional membrane filtration process without an electric field.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.113-122
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• 2002

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic crossflow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX, The wastewater was formulated the same as RDX hydrolysates, and consisted of acetate, formate, formaldehyde as carbon sources and nitrite, nitrate as electron accepters. The MBR system removed 80 to 90% of these carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressures, temperatures, suspended solids concentration, and organic loading rate in order to maximize treatment efficiency and permeate flux. Increasing transmembrane pressure and temperature did not improve membrane flux significantly. Increasing biomass concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was $0.72kg\;COD/m^3/day$, and the maximum F/M ratio was 0.50 kg N/kg MLSS/day and 1.82 kg COD/kg MLSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and $2.0m^3/m^2/day$ and was maintained by routine backwashing every 3 to 4 day. Backwashing with 2% NaOCl solution every fourth or fifth backwashing cycle was able to restore membrane flux to its original value.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.313-319
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• 2016

In this study, the performance experiment was conducted to compare the permeate flux of hollow fiber Vacuum Membrane Distillation module according to leak problem between module housing and membrane bundle. For the permeate flux performance experiment of the two Vacuum Membrane Distillation modules, the Lab-scale experimental equipment was built in the capacity of $1m^3/day$. The performance test of the two Vacuum Membrane Distillation modules were analyzed according to the feed water conditions. As a result, it was analyzed that the leak VMD module decreased about 14% of permeate flux than normal VMD module.