• Membrane and Water Treatment
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• v.11 no.5
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• pp.323-331
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• 2020

With the increasing demand on reverse osmosis (RO) membranes for water purification worldwide, the number of disposed membrane elements is expected to increase accordingly. Thus, recycling and reuse of end-of-life RO membranes should be a global environmental action. In this work, we aim to reuse the spent RO membrane for nanofiltration (NF) and ultrafiltration (UF) process by subjecting the spent membrane to solvent and oxidizing solution treatment, respectively. Our results showed that solvent-treated RO membrane could perform as good as commercial NF membrane by achieving similar separation efficiencies, but with reduced water permeability due to membrane surface fouling. By degrading the polyamide layer of RO membrane, the transformed membrane could achieve high water permeability (85.6 L/㎡.h.bar) and excellent rejection against macromolecules (at least 87.4%), suggesting its reuse potential as UF membrane. More importantly, our findings showed that in-situ transformation on the spent RO membrane using solvent and oxidizing solution could be safely conducted as the properties of the entire spiral wound element did not show significant changes upon prolonged exposure of these two solutions. Our findings are important to open up new possibilities for the discarded RO membranes for reuse in NF and UF process, prolonging the lifespan of spent membranes and promoting the sustainability of the membrane process.

• Clean Technology
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• v.9 no.3
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• pp.107-113
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• 2003

Printing process generates a vast amount of toxical waste and wastewater by the development of printing and publishing industry. The regulations for various environmental pollution material, which were indispensably used in printing industries, were getting stronger. The printing industries should develop the cleaner technologies in order to avoid the regulations. In this paper, the separation characteristics of microfiltration, ultrafiltration, reverse osmosis were surveyed to make basic data for the optimization of process as cleaner technologies for printing industries. The $2kg/cm^2$ of operation pressure were suitable to the U/F System. Because of the permeate of U/F was below 3 NTU as turbidity, which was probed to be possible using the rinsing water in printing process. U/F System,

• Membrane Journal
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• v.33 no.3
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• pp.87-93
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• 2023

Electrodialysis (ED) is essential in separating ions through an ion exchange membrane. The disposal of brine generated from seawater desalination is a primary environmental concern, and its recycling through membrane separation technology is highly efficient. Alkali is produced by several chemical industries such as leather, electroplating, dyeing, and smelting, etc. A high concentration of alkali in the waste needs treatment before releasing into the environment as it is highly corrosive and has a chemical oxygen demand (COD) value. The concentration of calcium and magnesium is almost double in brine and is the perfect candidate for carbon dioxide adsorption, a major environmental pollutant. Sodium hydroxide is essential for the metal carbonation process which, is easily produced by the bipolar membrane electrodialysis process. Various strategies are available for its recovery, like reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and ED. This review discusses the ED process by ion exchange membrane for alkali recovery are discussed.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.289-296
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• 2010

The purpose of this study is to evaluate various pre-treatment methods and proprieties of water quality for wastewater reuse using reverse osmosis (RO) processes. Secondary effluents were sampled from wastewater treatment plants and lab scale pre-treatments and RO filtration test were conducted systematically. Specifically, different types of pre-treatments, such as coagulation, microfiltration and ultrafiltration, were employed to evaluate the removal efficiency of particle and organic matters which may affect the membrane fouling rate. RO process was later added to eliminate trace amounts of remaining organic matters and salt from the raw water for wastewater reclamation. The permeate through the RO process satisfied water quality regulations for industrial water uses. The experimental results showed that the initial fouling tendency differed not only by the feed water properties but also by the membrane characteristics. Membrane fouling was greater for the membranes with large surface roughness, regardless of the hydrophobicity and zeta potentials. Thus both careful consideration of pre-treatment options and proper selection of RO membrane are of paramount importance for an efficient operation of wastewater treatment.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.69-73
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• 2013

This study is about the secondary concentration technology using electrodialysis process for minimum discharge and maximize recovery ratio from seawater desalination by reverse osmosis process. The experimental method adopted the constant voltage driving method and, concentrated/desalination volume capacity ratio changes, voltage changes and electrolyte types. Multi-ion membrane is used, aiming to derive conditions to minimize the TDS concentration of desalination water, to minimize the volumes of secnodary concentraion water and minimizing the power efficiency. The results of this study are as follows. The optimal ratio of concentraion/desalination volume is 1:5, the final TDS concentration of desalinated water is 5.32g/l, the final secnodary concentrated water salinity is 17.07% and electric energy demands of desalinated water is $16.74kWh/m^3$.

• Membrane and Water Treatment
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• v.8 no.4
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• pp.311-321
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• 2017

Hydrophilic and high modulus PPTA molecules were incorporated into PVDF matrix via the in situ polymerization of PPD and TPC in PVDF solution. PPTA/PVDF/NWF blend membrane was prepared through the immersion precipitation phase inversion method and nonwoven coating technique. The membrane integrated technology including PPTA/PVDF/NWF blend membrane and reverse osmosis (RO) membrane was employed to treat the polyester/viscose spunlace nonwoven process wastewater. During the consecutive running of six months, the effects of membrane integrated technology on the COD, ammonia nitrogen, suspended substance and pH value of water were studied. The results showed that the removal rate of COD, ammonia nitrogen and suspended substance filtered by PPTA/PVDF blend membrane was kept above 90%. The pH value of the permeate water was about 7.1 and the relative water flux of blend membrane remained above 90%. After the deep treatment of RO membrane, the permeate water quality can meet the water circulation requirement of spunlace process.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.367-375
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• 2006

Sequencing Batch Reactor (SBR) is well adopted for community wastewater treatment for its simplicity, performance and various advantageous treatment options. SBR is now drawing attention for its process modification such as coupled with membrane bioreactor, reverse osmosis or applying different media to achieve high removal efficiency. This study focused on the improved efficiency of carbon, nitrogen and phosphorous removal by applying zeolite materials called bioceramics to the SBR. Two laboratory-scale SBR units were operated in the same operating conditions - one with bioceramics called Bioceramic SBR (BCSBR) and the other without bioceramics used as control. Routine monitoring of COD, TP, $NH_3-N$, $NO_3-N$ was performed throughout this study. COD removal was about 80% to 100% and phosphorous removal was about 60% in the process whereas $NH_3-N$ removal efficiency was found to be 99.9% in the BCSBR unit. Addition of bioceramics also improved sludge characteristics such as sludge dewaterability, specific gravity and particle size. BCSBR can withstand high ammonia shock loading leading to the better treatment capacity of high ammonia containing wastewater. The cause of improved removal efficiencies within the biological reactor could be attributed to the biochemosorption mechanisms of bioceramics. Absorption/adsorption or desorption capacity of bioceramics was tested through laboratory experiments.

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

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.226-232
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• 2013

Several pretreatment processes such as softening, coagulation and precipitation, activated carbon adsorption, ion-exchange and neutralization processes were studied to remove organics and inorganics for selection of the RO based reusing system of metal industry wastewater. The effects of the hydrophobic/hydrophilic fractions of the organics on DOC removal were tested and used to optimize the combination process. Among various pretreatment processes, softening could reduce 93.4% of hardness and could remove all hydrophobic organics from the effluent of metal industry wastewater. Softening followed by coagulation process could reduce DOC (Dissolved Organic Carbon) from 5.1 mg/L to 1.6 mg/L. In addition, as a result of physiochemical pretreatment to raw wastewater of metal industry, neutralization with NaOH showed an efficient removal of iron and TDS (Total Dissolved Solids) without increase in the hardness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.485-492
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• 2021

This study focused on safety aspects surrounding energy consumption in the seawater desalination process in the Daesan Industrial Complex located on the West Sea coast. The safety index for energy consumption was evaluated under different salinities and temperatures of the incoming seawater. Temperature and salinity input data for the 1997-2018 period were obtained from the Marine Environment Information System, and the power required for reverse osmosis (RO) was applied to the program as per the data provided by the RO membrane manufacturer (Q-Plus v3.0). Notably, reasonable energy consumption guidelines were proposed during the design of the desalination facilities; in this regard, the desalination process required approximately 2.10-2.90 kWh/m³ electrical power. Moreover, the energy safety based on 95 % was estimated to be 2.80 kWh/m³ when the desalination facility was operated.