• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.1-10
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• 2000

An experimental study regarding the effect of emulsions on RO is presented. Heavy oil was added to the sea water and the distilled water separately and treated for 30 minutes by a homogenizer to make emulsions. For the case of the sea water without heavy oil the permeate decreased from the beginning of the experiment. Chloride and conductivity increased with time, due to the fouling occurring as the suspended solids in the sea water accumulated on the membrane surface. Rejection rate of salt was 99.6~99.7%. As for the sea water containing heavy oil, the permeate decreased slowly from the beginning of the experiment. This result was the same for the case of the sea water only. However. chloride and conductivity increased significantly when heavy oil was added. In the second experiment with sea water containing heavy oil, the operation time of RO was reduced considerably. With addition of oil, the chloride increased greatly, while the permeate reduced comparatively. In the experiment where emulsion of $0.3{\sim}0.8mg/{\ell}$ was supplied to RO. oil concentration was about 10ppb in the permeate at the end of the experiment. In case of the distilled water containing heavy oil. the conductivity increased. However. the permeate reduced to 30% compared to the case of the sea water containing heavy oil. The case of sea water containing heavy oil showed an opposite result, but the effect of the addition of oil on RO was significant. Oil caused fouling of the RO and the contamination of the whole system, and as the result the system could not be operated properly. As a result the membrane capacity, the amount and water quality of permeate deteriorated significantly.

• Membrane Journal
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• v.15 no.1
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• pp.52-61
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• 2005

Permeate flux decline in a microfiltration was analyzed by measuring the permeability of bentonite colloidal solution through polyethylene capillary membranes. The flux decline with time was due to the growth of cake layer on the membrane surface and to the pore blocking by particles. As the time approaches to steady state, the permeate flux is almost controlled by the cake filtration model. Faster flux decline at high trans-membrane pressure was attributed to the formation of denser packed cake layer and pore blocking. The ratio of permeate flux to the initial permeate flux, J/J₁, decreased with increasing the trans-membrane pressure, from 45% for 0.5 kg/sub f//㎠ to 38% for 2.0 kg/sub f//㎠. In comparing the ratio of each fouling component to the total fouling for the 0.5 kg/sub f//㎠ TMP condition, complete blocking was 23.4%, standard blocking was about 14.6% and cake filtration was 62.0%, respectively. Permeate flux through the membrane increases with cross flow velocity, and the effect of the variation of velocity is more significant at 1.0 kg/sub f//㎠ rather than at 2.0 kg/sub f//㎠ of the operation pressure. Permeate flux for the membrane having the average pore diameter of 0.34 ㎛ was higher than that for the membrane of 0.24 ㎛ pore size, with the higher flux with the low concentration of feed. On the operation using the membrane of 0.34 ㎛ pore, the pore blocking in the low concentration of 200 ppm is negligible relative to the pore blocking in the 1000 ppm feed.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.253-271
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• 2010

A theoretical study for the flux enhancement by pulsation of transmembrane pressure is presented for osmotic pressure controlled ultrafiltration under laminar flow regime. The transient velocity profile is solved analytically using Green's function method. Time dependent convective diffusive equation is solved to quantify the membrane surface concentration and the permeate flux, numerically. The effects of the amplitude and frequency of pulsation on flux, surface concentration and observed retention are studied.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.495-502
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• 2013

This work was performed to investigate proper condition of coagulation treatment as UF process pretreatment that consider UF permeate flux and residual Al concentration. The coagulant used an alum as $Al_2(SO_4)_3{\cdot}16H_2O$ and PACl (r = 1.5) made this study. The experiment was tested in adjusting conditions such as alum dose, flocculation time and coagulation pH of seawater. Consequently, higher coagulant dose lead to elevation of UF permeate flux while residual aluminium also increased in condition of pH 8.0. The most suitable condition which has a good permeate flux and low residual aluminium, in this works, was coagulant dose of 0.7 mg/L (as Al, alum) and 1.2 mg/L (as Al, PACl) and coagulation pH 6.5. In addition, applying the flocculation time with 1.2 mg/L of PACI reduced. The flocculation time reduced UF permeate flux in using alum.

• Membrane Journal
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• v.18 no.2
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• pp.168-175
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• 2008

This study was carried out for the plate and frame membrane modules equipped with and without plastic protuberances on the support frame in order to determine the effect of eddy flow induced by the protuberances on permeate flux. The initial time for rapidly declined permeate flux on the module with protuberances was delayed twice or more than that on the module without protuberances when kaolin solution was permeated at the operating pressures from 0.4 to 1.6 bar. Also decreasing ratio of the kaolin solution to pure water flux for module with protuberances was 1 to 5% lower than that for module without protuberances. The flux improvement due to protuberances at laminar flow corresponding Reynolds number 1,750 was about double as compared with that in the transition flow region. In general, the kaolin fouling reduction for the plate module with protuberances during initial filtration process was very effective, even though the permeate flux after 60 minutes filtration did not increase significantly.

• Membrane Journal
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• v.25 no.1
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• pp.7-14
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• 2015

In this study transmembrane pressure (TMP) was measured with respect to operational time in order to estimate fouling of the submerged membrane in the membrane bioreactor(MBR). The microfiltration flat sheet module which has $0.02m^2$ of effective area and $0.15{\mu}m$ nominal pore size was submerged in the activated sludge solution of MLSS 5,000 mg/L. The permeate experiments were carried out simultaneously to compare TMP of the run/stop (R/S) with that of the sinusoidal flux continuous operation (SFCO). TMP for SFCO mode was up to 93% lower than that of R/S mode, and the effect of TMP drop reduced as permeate flux increased. Also, TMP of the SCFO mode was maintained below 40% of the limited operating TMP 55 kPa until the permeate operational time extended to longer than 5 times for the case as the coagulant $FeCl_3$ was dosed into the activated sludge solution with 500 mg/L concentration.

• Membrane Journal
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• v.9 no.4
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• pp.209-214
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• 1999

The purpose of this research was to investigate the permeation properties of each stage in three stage reverse osmosis system for cold-mill wastewater reuse. After construction of the three staged pilot plant which had 75% recovery and equipped with seven plate-and-frame modules, the change of each stage's penneate flow and quality were investigated in the process of membrane fouling. The order of average permeate flow was first, second, and third stage at the beginning. As the operation time passed, the permeate flow of first stage was decreased, the second stage was maintained steadily, and the third stage was increased. Accordingly, the fouling was initiated at the first stage and then progressed to the second and third stage. The first stage's permeate quality showed the best and the second and third stage was the next in that order. And the order of quality was maintained during the test periods. Therefore, the permeate quality was not affected by membrane fouling.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.248-253
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• 2014

Air Gap Membrane Distillation (AGMD) is one of several technologies that can be used to solve problems fresh water availability. AGMD exhibits several advantages, including low conductive heat loss and higher thermal efficiency, due to the presence of an air gap between the membrane and condensation wall. A previous study by Bhardwaj found that the condensation surface properties (materials and contact angle) affected the total collected fresh water in the solar distillation process. However, the process condition differences between solar distillation and AGMD might result in different condensation phenomena. In contrast, N. Miljkovic showed that a hydrophobic surface has higher condensation heat transfer. Moreover, to the best of our knowledge, there is no study that investigates the effect of condensation surface properties in AGMD to overall process performance (i.e. flux and thermal efficiency). Thus, in this study, we treated the AGMD condensation surface to make it hydrophobic or hydrophilic. The condensation surface could be made hydrophilic by immersing and boiling plate in deionized (DI) water, which caused the formation of hydrophilic aluminum hydroxide (AlOOH) nanostructures. Afterwards, the treated plate was coated using hexamethyldisiloxane (HMDSO) through plasma-enhanced chemical vapor deposition (PECVD). The result indicated that condensation surface properties do not affect the permeate flux or thermal efficiency significantly. In general, the permeate flux and thermal efficiency for the treated plates were lower than those of the non-treated plate (pristine). However, at a 1 mm and 3 mm air gap, the treated plate outperformed the non-treated plate (pristine) in terms of permeate flux. Therefore, although surface wettability effect was not significant, it still provided a little influence.

• Membrane Journal
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• v.4 no.4
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• pp.197-204
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• 1994

In this study, permeation characteristics of pure $CH_4,\;CO_2$ and $CH_4/CO_2$ gas mixture were examined by permeation experiments through hollow fiber membrane module and experimental results were compared with simulation results. Permeation rate of pure gas increased with increaseing temperature in Arrhenius type. Activation energy was 6.61 kJ/mol for $CO_2$ and 25.26 kJ/mol for $CH_4$. In the permeation experiment of gas mixture, permeate flow rate and $CO_2$ concentration in permeate decreased and $CH_4$ concentration in reject increased with the increase of cut. Separation factor was in the range of 20~40 at 5~20 atm and 20% cut and it increased with pressure and against temperature Experimental values corresponded to numerical values with the deviation of 8% in permeate flow rate and $CO_2$ concentration in permeate and 15% in $CO_2$ concentration in reject.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.3
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• pp.229-236
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• 2017

In this study, a direct contact membrane module was manufactured to be used in a pilot scale membrane distillation process to treat $3m^3/day$ of the digestate produced from anaerobic digestion of livestock manure. In order to investigate the performance of the membrane module, permeate flux was measured with and without spacer inside the module under various condition of temperature difference and cross flow velocity (CFV) through the membrane surfaces. Flux recovery rate after chemical cleaning was also investigated by applying three different cleaning methods. Additionally, thermal energy consumption was theoretically simulated based on actual pilot plant operation conditions. As results, we observed flux of the module with spacer was almost similar to the theoretically predicted value because the installation of spacer reduced the channeling effect inside the module. Under the same operating condition, the permeate flux also increased with increasing temperature difference and CFV. As a result of chemical in-line cleaning using NaOCl and citric acid for the fouled membranes, the recovery rate was 83.7% compared to the initial flux when NaOCl was used alone, and 87% recovery rate was observed when only citric acid was used. However, in the case of using only citric acid, the permeate flux was decreased at a rapid rate. It seemed that a cleaning by NaOCl was more effective to recover the flux of membrane contaminated by the organic matter as compared to a cleaning by citric acid. The total heat energy consumption increased with increasing CFV and temperature difference across the membrane. Thus, further studies should be intensively conducted to obtain a high permeate flux while keeping the energy consumption to a minimum for a practical application of membrane distillation process to treat wastewater.