• Membrane and Water Treatment
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• 제10권4호
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• pp.259-264
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• 2019

Cost effective clay adsorptive microfiltration membranes were synthesized to remove Cr (III) from high polluted water. Raw and calcined bentonite were mixed in order to decrease the shrinkage and also increase the porosity; then, 20 wt% of carbonate was added and the samples, named B (without carbonate) and B-Ca20 (with 20 wt% calcium carbonate) were uniaxially pressed and after sufficient drying, fired at $1100^{\circ}C$ for 3 hours. Then, physical and mechanical properties of the samples, their phase analyses and microstructure and also their ability for Cr(III) removal from high polluted water (including 1000 ppm Cr (III) ions) were studied. Results showed that the addition of calcium carbonate lead the porosity to increase to 33.5% while contrary to organic pore formers like starch, due to the formation of wollastonite, the mechanical strength not only didn't collapse but also improved to 36.77 MPa. Besides, sample B-Ca20, due to the presence of wollastonite and anorthite, could remove 99.97% of Cr (III) ions. Hence, a very economic and cost effective combination of membrane filtration and adsorption technology was achieved for water treatment which made microfiltration membranes act even better than nanofiltration ones without using any adsorptive nano particles.

• Membrane and Water Treatment
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• 제1권2호
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• pp.103-120
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• 2010

Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilic-hydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

• Environmental Engineering Research
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• 제22권4호
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• pp.377-383
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• 2017

A tube-type ceramic membrane for microfiltration was developed, and the membrane module comprised of three membranes was also applied to biological carbon and nitrogen removal processes for post-treatment. Manufacturing the microfiltration membrane was successful with the structure and boundary of the coated and support layers within the membrane module clearly observable. Total kjeldahl nitrogen removal from effluent was additionally achieved through the elimination of solids containing organic nitrogen by use of the ceramic membrane module. Removal of suspended solids and colloidal substances were noticeably improved after membrane filtration, and the filtration function of the ceramic membrane could also easily be recovered by physical cleaning. By using the ceramic membrane module, the system showed average removals of organics, nitrogen, and solids up to 98%, 80% and 99.9%, respectively. Thus, this microfiltration system appears to be an alternative and flexible option for existing biological nutrient removal processes suffering from poor settling performance due to the use of a clarifier.

• Membrane and Water Treatment
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• 제11권4호
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• pp.275-282
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• 2020

Hranfa's marl, a local natural mineral, is selected for the decontamination by adsorption of aqueous effluents in textile industry. Its physicochemical characterization is first performed. It is composed mainly of Calcite, Quartz, Ankerite and Muscovite. Its specific surface area is 40 ㎡ g^-1. Its adsorption performance is then tested in batch conditions using an industrial organic dye, Bemacid Red E-TL, as a model pollutant. The measured adsorption capacity of Hranfa's marl is 16 mg g^-1 which is comparable to that of other types of natural adsorbents. A hybrid process is tested coupling adsorption of the dye on marl in suspension and microfiltration. An adsorption reactor is inserted into the circulation loop of a microfiltration pilot using ceramic membranes. This makes possible a continuous extraction of the treated water provided that a periodic replacement of the saturated adsorbent is done. The breakthrough curve obtained by analyzing the dye concentration in the permeate is close to the ideal one considering that no dye will cross the membrane as long as the adsorbent load is not saturated. These first experimental data provide proof of concept for such a hybrid process.

• 상하수도학회지
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• 제18권6호
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• pp.801-806
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• 2004

The pilot study was conducted to (i) investigate the ability of various membrane integrity monitoring methods to detect changes in membrane integrity during operation, and (ii) determine the impact of membrane damage on microbial removal by microfiltration. Two variations of air pressure hold tests were investigated for direct integrity monitoring: pressure decay (PD) and diffusive air flow (DAF) tests which are most commonly used integrity tests for microfiltration (MF) membranes. Both PD and DAF tests were sensitive enough to detect one damaged fiber out of 66,000 under field operaing conditions. Indirect integrity monitoring such as turbidity and particle counting, however, responded poorly to defects in membrane systems. Microbial challenge study was performed using both new and deliberately damaged membranes, as well as varying the state of fouling of the membrane. This study demonstrated that MF membrane with nominal pore size $0.2{\mu}m$ was capable of removing various pathogens including coliform, spore, and cryptosporidium, at the level required by drinking water regulations, even when high operating pressures were applied. A sharp decrease in average log reduction value (LRV) was observed when one fiber was damaged, emphasizing the importance of membrane integrity in control of microbial contamination.

• 멤브레인
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• 제17권4호
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• pp.381-386
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• 2007

니켈입자와 고분자를 함유한 니켈슬러리를 상전환법을 이용하여 중공사 형태로 성형한 후, 소결법을 이용하여 $1,150^{\circ}C$ 환원조건에서 소결하여 금속 필터를 제조하였고 니켈 입자를 표면에 함침한 후, $800^{\circ}C$ 환원조건에서 소결하여 금속 정밀여과막을 제조하였다. 소결조건에 따른 금속 중공사 필터와 정밀여과막의 기공크기, 강도를 살펴보았다. 금속 중공사 정밀여과막은 산, 염기 및 염소에 대한 저항성이 뛰어났으며 역세척에 의한 투수량 회복률이 우수하였다.

• 멤브레인
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• 제22권4호
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• pp.243-250
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• 2012

본 연구에서는 정수처리용 알루미나 정밀여과 및 광촉매의 혼성공정에서 물역세척 주기(filtration time, FT) 변화의 영향을 알아보고, 탄소 정밀여과막 또는 알루미나 한외여과막을 사용한 기존 결과들과 비교하였다. 물역세척 시간(BT)는 10초로 고정한 채, FT를 2~10분으로 변화시키면서, 그 영향을 180분 운전 후 막 오염에 의한 저항($R_f$), 투과선속(J)과 총여과부피($V_T$) 측면에서 고찰하였다. FT가 감소할수록, $R_f$는 감소하고 J는 증가하여 탄소 정밀여과막 또는 알루미나 한외여과막을 사용한 기존 결과들과 동일하였다. 탁도의 처리효율은 98.1% 이상으로 높게 나타났으며, FT 변화에 의한 영향이 보이지 않아 탄소 정밀여과막을 사용한 기존의 결과와 유사하였다. 한편, 유기물의 처리효율은 FT 8분 조건에서 89.6%로 가장 높았으며, FT 변화의 영향이 보이지 않았고 기존의 결과들보다 다소 높은 유기물 제거율을 보였다.

• Membrane and Water Treatment
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• 제9권4호
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• pp.285-292
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• 2018

In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high $R^2$ value). Finally, the results present that ANN provide best results ($R^2$ value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

• 한국환경보건학회지
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• 제23권4호
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• pp.67-72
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• 1997

To evaluate the effectiveness of water treatment using nanofiltration, ultrafiltration, and microfiltration systems, tapwater contaminated by bacteria and nitrate nitrogen was filtered, and then the rates of removal for many kinds of contaminants were comp.ared and investigated. The rates of turbidity removal by these systems are around 80% all of them. However, nanofiltration system is the most effective as hardness removal is 80%, suspended solids 90%, total residual chlorine 90% and nitrate nitrogen 69%. Among nanofiltration, ultrafiltration and microfiltration systems, nanofiltration system is the most stable in flow rate of permeate. Comparing hollow and spiral type of ultrafiltration, microfiltration each, spiral type is more stable than hollow type owing to rinsing effect of brine. The values of pH in ultrafiltration and microfiltration systems are between 7, 0 and 7.5, and that of nanofiltration system is low to 6.2-7.0. The effectiveness of heterotrophic bacteria removal is the most excellent in the nanofiltration system.

• Membrane and Water Treatment
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• 제7권1호
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• pp.55-70
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• 2016

Microfiltration/ultrafiltration (MF/UF) Adsorptive polyamide-6 (PA-6) membranes were prepared using wet phase inversion process. The prepared PA-6 membranes are characterized by scanning electron microscopy (SEM), porosity and swelling degree. In this study, the membranes performance has examined by adsorptive removal of copper ions from aqueous solutions in a batch adsorption mode. The $PA-6/H_2O$ membranes display sponge like and highly porous structures, with porosities of 41-73%. Under the conditions examined, the adsorption experiments have showed that the $PA-6/H_2O$ membranes had a good adsorption capacity (up to 120-280 mg/g at the initial copper ion concentration ($C_0$) = 680 mg/L, pH7), fast adsorption rates and short adsorption equilibrium times (less than 1.5-2 hrs) for copper ions. The fast adsorption in this study may be attributed to the high porosities and large pore sizes of the $PA-6/H_2O$ membranes, which have facilitated the transport of copper ions to the adsorption. The results obtained from the study illustrated that the copper ions which have adsorbed on the polyamide membranes can be effectively desorbed in an Ethylene dinitrilotetra acetic acid Di sodium salt ($Na_2$ EDTA) solution from initial concentration (up to 92% desorption efficiency) and the PA-6 membranes can be reused almost without loss of the adsorption capacity for copper ions. The results obtained from the study suggested that the $PA-6/H_2O$ membranes can be effectively applied for the adsorptive removal of copper ions from aqueous solutions.