• Membrane and Water Treatment
• /
• v.6 no.4
• /
• pp.309-321
• /
• 2015

We report in this study the synthesis of mixed matrix reverse osmosis membranes by interfacial polymerization (IP) of thin film nanocomposite (TFNC) on porous polysulfone supports (PS). This paper investigates the synthesis of ZnO nanoparticles (NPs) using the sol-gel processing technique and evaluates the performance of mixed matrix membranes reached by these aerogel NPs. Aqueous m-phenyl diamine (MPD) and organic trimesoyl chloride (TMC)-NPs mixture solutions were used in the IP process. The reaction of MPD and TMC at the interface of PS substrates resulted in the formation of the thin film composite (TFC). NPs of ZnO with a size of about 25 nm were used for the fabrication of the TFNC membranes. These membranes were characterized and evaluated in comparison with neat TFC ones. Their performances were evaluated based on the water permeability and salt rejection. Experimental results indicated that the NPs improved membrane performance under optimal concentration of NPs. By changing the content of the filler, better hydrophilicity was obtained; the contact angle was decreased from $74^{\circ}$ to $32^{\circ}$. Also, the permeate water flux was increased from 26 to 49 L/m2.h when the content of NPs is 0.1 (wt.%) with the maintaining of lower salt passage of 1%.

• Membrane and Water Treatment
• /
• v.9 no.5
• /
• pp.373-383
• /
• 2018

Fouling by solids and microorganisms is the major obstacle limiting the efficient use of membrane wastewater treatment. In our previous study, two stages microalgae/membrane filtration system was proposed to treat anaerobic digested palm oil mill effluent (AnPOME). This two stages microalgae/membrane filtration system had showed great potential for the treatment of AnPOME with high removal of COD, $NH_3-N$, $PO_4{^{3-}}$, TSS, turbidity, and colour. However, fouling behavior of the membrane in this two stages microalgae/membrane filtration system was still unknown. In this study, empirical models that describe permeate flux decline for dead-end filtration (pore blocking - complete, intermediate, and standard; and cake layer formation) presented by Hermia were used to fit the experimental results in identifying the fouling mechanism under different experimental conditions. Both centrifuged and non-centrifuged samples were taken from the medium with 3 days RT intervals, from day 0 to day 12 to study their influence on fouling mechanisms described by Hermia for ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) filtration mode. Besides, a more detailed study on the use of resistance-in-series model for deadend filtration was done to investigate the fouling mechanisms involved in membrane filtration of AnPOME collected after microalgae treatment. The results showed that fouling of UF and NF membrane was mainly caused by cake layer formation and it was also supported by the analysis for resistance-in-series model. Whereas, fouling of RO membrane was dominated by concentration polarization.

• Membrane Journal
• /
• v.31 no.3
• /
• pp.170-183
• /
• 2021

Fouling has continued to be a problem that hinders the effectiveness of membrane properties. To solve this problem of reducing fouling effects on membrane surface properties, different and innovative types of membrane patterning has been proposed. This article reviews on the progress of patterned membranes and their separation process concerning the fouling effects of membranes. The types of separation processes that utilize the maximum effectiveness of the patterned membranes include nanofiltration (NF), reverse osmosis (RO), microfiltration (MF), ultrafiltration (UF), and pervaporation (PV). Using these separation processes have shown and prove to have a major effect on reducing fouling effects, and in addition, they also add beneficial properties to the patterned membranes. Each patterned membrane and their separation processes gave notable results in threshold towards flux, salt rejections, hydrophilicity and much more, but there are also some unsolved cases to be pointed out. In this review, the effects of patterned membrane for separation processes will be discussed.

• Membrane Journal
• /
• v.22 no.4
• /
• pp.235-242
• /
• 2012

Ammonium perchlorate (AP) is primarily derived from the process of liquid incineration treatment when dismantling a solid rocket propellant. A series of batch dead-end nanofiltration (NF) and reverse osmosis (RO) membrane experiments were conducted to explore the retention mechanisms of AP under various hydrodynamic and solution conditions. Low levels of silicate type of siloxane had been detected through the GC/MS and FTIR analysis of liquid solutions extracted from solid ammonium perchlorate composite propellant (APCP). It is indicated that NF/RO membranes fouling in the presence of APCP was mainly attributed to the AP interactions because the concentration of silicate type of siloxane was negligible compared to that of AP. The osmotic pressure of AP was presumably resulted in the flux declines ranging from 13 to 17% in the case of the application of low-pressure (551 and 896 kPa for NF and RO) compared to those in application of high-pressure. The retention of AP by NF/RO membranes significantly varied from approximately 10 to 70% for NF and 26 to 87% for RO, depending on the operating and solution water chemistry conditions. The results suggested that retention efficiency of AP was fairly increased by reducing concentration polarization (i.e. application of low-pressure and stirring speed of 600 rpm) and increasing the pH of a solution. The result of this study was also consistent with the previous modeling of 'solute mass transfer of NF/RO membranes' and demonstrated that hydrodynamic and solution water chemistry conditions are to be a key factor in the retention of AP by NF/RO membranes.

• Membrane Journal
• /
• v.8 no.2
• /
• pp.77-85
• /
• 1998

To treat effectively EDIR (electrodeposition ion removal) wastewater in terms of CO$_{Mn}$ 1,500~2,000 ppm generated from aluminum painting process, a RO (reverse osmosis) process was designed and installed to recover and reuse the concentrated solvent sent back to the electrocodeposition tank while the permeate reused as rinse water. A RO system in which three polyamide-spiral wound modules ($102\Phi \times 1,016L$ mm) connnected in series had been running to treat 20 m$^3$ in waste volume in 3 days batch operation at the condition of system recovery of 30 %, applied pressure 11.5 $kg_f/cm^2$ and room temperature. During 42 hours continuous operation leading to 5-fold decrease in waste volume, nearly constant permeation flux of 390 l/m$^2$-hr was maintained and the permeate with average CO$_{Mn}$, 300 ppm was obtained which could be used for washing the remaining paint solution in ion-exchange tower instead of demineralized water. Also COD$_{Mn}$ rejection as a function of running time was observed to be in the range of 78~87 % and the observed solvent rejections for ethyl cellusolve, buthyl cellusolve and n-butanol were 79 %, 87 % and 70 %, respectively.

• Membrane Journal
• /
• v.18 no.1
• /
• pp.94-102
• /
• 2008

For the treatment of the dye wastewater, a polyamide nano-composite membrane and reverse osmosis (RO) membranes were prepared using interfacial polymerization technique, in which piperazine, meta-phenylene diamine, and trimesoyl chloride were used as monomers, Their permselective properties were characterized with aqueous solutions of PEG 600, $Na_2SO_4$, and NaCl, and their performance was compared with that of Osmonics Co, They were found to be a typical nano-composite membrane and a low pressure RO membrane. Using them, a real dye wastewater supplied from the Kyungin Corporation, one of the domestic dye producer, was treated, studying the separation performances of the membranes, Also, during the wastewater treatment, cleaning in place (CIP) of the membranes was carried out regularly to recover the flux of the membranes. Three different chemical cleaners were employed for the CIP process and their performance were compared in this study.

• Membrane Journal
• /
• v.22 no.6
• /
• pp.481-488
• /
• 2012

The anionic exchange polymer, poly(vinyl amine)(PVAm), was coated onto polyamide (PA) reverse osmosis (RO) membranes by using 'salting-out' method. The effects of the fouling phenomena for these PVAm coated membranes were investigated using the model foulants, bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA). The surface coating and the fouling phenomena were observed by the scanning electron microscopy. And the flux was measured for each 100 ppm of above foulant aqueous solution at the operating pressure, 2, 4, 8 bar. The PVAm-coated PA membranes showed somewhat fouling improvements and the fouling reduction was shown in the order of HA > SA > BSA, particularly HA case was distinct.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.12
• /
• pp.1273-1280
• /
• 2008

This study sought to establish the optimum operating condition for the recovery of caustic (NaOH) solution from mercerization in textile process. As main factors, the silt density index (SDI) evaluation of ceramic membrane for the application of nanofiltration/reverse osmosis (NF/RO) membrane, the recovery yield measurement of caustic solution for the application of polymeric membrane, the optimum condition of chemical cleaning for the membrane regeneration, the optimum removal condition of total organic carbon (TOC), turbidity, color, and the permeate flux of ceramic membrane/polymeric membrane combined process were investigated. As results, ceramic ultrafiltration (UF) in the first step and nanofiltration (NF) in the second step were found to be suitable for the removal of total suspended solid (TSS), residual organics, turbidity including color, and the recovery of caustic solution from caustic wastewater stream in mercerization process. When only the ceramic UF membrane was used, the rejection efficiency of both of TSS and turbidity was more than 99.0%, and the color and TOC were rejected about 74.7% and 49.2%, respectively. Meanwhile, the combined membrane precess of UF and NF membranes showed even more efficient removal abilities and thus more than 99.9% of TSS and turbidity, 87.7% of color, and 78.2% of TOC were removed. In particular, 91.3% of NaOH was successfully recovered with 83.7% of total volume in the combined membrane process. With this regard, a clean caustic solution was obtained in a high purity, which can be reused for mercerization process, expecting to offer economical benefits.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.1
• /
• pp.51-57
• /
• 2009

Biofouling in seawater reverse osmosis (SWRO) desalination process causes many problems such as flux decline, biodegradation of membrane, increased cleaning time, and increased energy consumption and operational cost. Therefore biofouling is considered as the most critical problem in system operation. To control biofouling in early stage, detection of the most problematic bacteria causing biofouling is required. In this study, six model bacteria were chosen; Bacillus sp., Flavobacterium sp., Mycobacterium sp., Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhodobacter sp. based on report in the literature and phylogenetic analysis of seawater intake and fouled RO membrane. The adhesion to RO membrane, the high pressure resistance, and the hydrophobicity of the six model bacteria were examined to find out their fouling potential. Rhodobacter sp. and Mycobacterium sp. were found to attach very well to RO membrane surface compared to others used in this study. The test of hydrophobicity revealed that the bacteria which have high hydrophobicity or similar contact angle with RO membrane ($63^{\circ}$ of contact angle) easily attached to RO membrane surface. P. aeruginosa which is highly hydrophilic ($23.07^{\circ}$ of contact angle) showed the least adhesion characteristic among six model bacteria. After applying a pressure of 800 psi to the sample, Rhodobacter sp. was found to show the highest reduction rate; with 59-73% of the cells removed from the membrane under pressure. P. fluorescens on the other hand analyzed as the most pressure resistant bacteria among six model bacteria. The difference between reduction rates using direct counting and plate counting indicates that the viability of each model bacteria was affected significantly from the high pressure. Most cells subjected to high pressure were unable to form colonies even thought they maintained their structural integrity.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.4
• /
• pp.169-179
• /
• 2017

This study was conducted to supply information that can be utilized as data for desalination plant construction in the future by estimating unit cost of water production in the potential site of Incheon, Daesan, Yeosu, Busan, Ulsan and Sokcho in Korea. The production costs in Sokcho and Ulsan were similar to those of Busan and Yeosu. Those four sites showed better economic range due to low construction cost for intake facility compared to Incheon and Daesan. Although the salinity measured in the above 6 sites did not show perceptible effect on the production cost, the difference of seasonal seawater temperature needs to be considered due to the change of flux in reverse osmosis (RO) membrane. It turned out that the most critical parameters are the amortization in a year by the analysis of life cycle and the capacity of plant. Incheon and Daesan showed the difference of production cost up to 29% at the condition of amortization in 25 year, and up to 22% depending on plant capacity. However, the production cost in this study did not take into account of other indirect costs, therefore, this should be considered as the minimum cost.