• Membrane Journal
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• v.32 no.2
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• pp.83-90
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• 2022

Wastewater from refineries and petroleum plant lead to severe environmental pollution. There are various existing processes applied for oily water treatment, but membrane-based technology is one of the most efficient methods. Polymeric membranes prepared from organic materials for the separation of oil in water often face chronic problem of membrane fouling. Inorganic membranes are considered to be more efficient due to longer lifetime than organic membranes. Zeolite membranes have better chemical stability and long-term recyclability. The presence of hydrophilicity enhances the water flux of membrane. Ceramic membranes prepared from zeolites are another efficient class of inorganic membranes applied for oil water separation. This review is focused on oily wastewater separation based on zeolite membrane which classified into two categories, i) neat zeolite and ii) zeolite composites with other materials.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.289-294
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• 2022

Oil contained in domestic and industrial wastewater or marine spilled oil gives rise to severe environmental pollution issues such as water pollution and ecosystem destruction. The membrane filtration method as one of representative oil/water separation strategies has technological challenges such as membrane fouling and low separation rate. In this work, we devise a 3D-printed microhydrocyclone for oil/water separation by utilizing a digital lighting processing-based 3D printer. We demonstrate that the 3D-printed microhydrocyclone can effectively separate oil and water phases from oil-in-water emulsion.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.13-22
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• 2015

The combined impact of Dissolved Organic Matter (DOM) fouling and inorganic ($CaSO_4,Ca_3(PO_4)_2$) scaling on the retention of TNT (2, 4, 6-Trinitrotoluene), RDX (Hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine) and HMX (1, 3, 5, 7-Tetranitro-1, 3, 5, 7-tetrazocane) explosive contaminants by nano-filtration membrane were studied, since organic fouling and salt scaling are the major limitations for membrane filtration. Results reported here indicate that DOM fouling layer with a humic acid does not necessarily lead to an immediate loss of permeate flux but can result in a severe impact on the flux loss when both humic acid and inorganic scaltants were presented simultaneously. The $Ca_3(PO_4)_2$ mixed with humic acid showd most sever flux loss (42%) compared to that of only humic acid presence (8%). It could be a result that the scaling formation of the NF membrane was dominated by cake layer formation of DOM and it was along with pore blocking by the formation of crystals inside the porous active matrix of the NF membrane. In addition, these results indicated that the membrane selectivity of the explosives retention trended correlated with respect to increasing explosives size (listed by MW) based on greater steric interactions and followed the order (MW, g $mol^{-1}$; removal, %): HMX (296.15; 83%) ${\gg}$ RDX (222.12; 49%) ≋ TNT (227.13; 32%). Because the scaling and fouling layer could lead to a additional cake-enhanced concentration polarisation effect, the retention of explosives with the presence of humic acid in the feed solution and inorganic scaling formation on top of an organic fouling layer do not differ substantially retention from that of pure DI feed and NaCl solution.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2187-2195
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• 2000

A water treatment system using membrane separation technology can provide stable effluent quality and its maintenance is relatively easy comparing to the conventional water treatment system. In addition, the membrane filtration system is very compact such that it can replace existing water treatment processes of coagulation/sedimentation/filtration by only one process. However, a major problem associated with membrane filtration is flux decline with operating time due to concentration polarization and fouling, so a systematic study on evaluation of long-term filtration performance is necessary. A membrane filtration system using tubular type ultrafiltration membranes with MWCO of 30.000 Da was constructed for this study and it had been operated in a feed-and-discontinuous bleed mode. Flux was stabilized after operation of 1.500 hours and maintaining above 25 LMH until 4.000 hours. Contaminants causing SS and turbidity were almost completely removed while the $UV_{260}$ and DOC removals were 55% and 49%, respectively. A simple mass balance equation was developed to predict maximum concentrations of SS, turbidity, $UV_{260}$ and DOC in a operation cycle. For SS and turbidity the measured max, concentrations in each cycle agree well with the predicted values while the measured max, concentrations of $UV_{260}$ and DOC were 59% and 37% of the predicted values, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1273-1280
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• 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
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• v.29 no.6
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• pp.654-661
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• 2007

The goal of this research was to identify the impact of silicate polymerization on the formation of insoluble aluminiumsilicate salts which could be a cause of irreversible fouling in the membrane process by lab-scale test. For this, the amount and characteristics of precipitates that were formed in six samples with different Al and Si concentration were analyzed. And the particles was also observed by SEM-EDS(Scanning Electron Microscope - Electron Dispersion Spectrophotometer) to compare morphology and ratio of Al and Si in each precipitates. Finally the reactive and nonreactive silicate contents in the solution and precipitates were analyzed to calculate silicate form content in each fraction. The amount of precipitates was in proportion to the total concentration of both element in solution. And the amount of insoluble particle that was not dissolved in the acid solution was recorded the highest in the sample 2 of which Si concentration was lower than the saturation concentration, 50 mg/L. The content of reactive silicate in precipitates was also recorded the highest value in sample 2 of which almost silicate form was reactive. When the silicate concentration is same, that value was recorded the highest in the sample with highest Al concentration. The SEM morphology of the precipitates was similar to that of Aluminiumhydroxide and the insoluble precipitates was not dissolved in acidic solution with pH 2.7 was able to observed only in sample 2. The ratio of Al and Si in the precipitates was ranged $0.48\sim3.14$, thai of sample 2 was recorded the highest value, 3.14. It is concluded that the insoluble aluminiumsilicate could be easily formed in the solution of which silicate exist as a reactive form and coexisting Al is sufficient.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.119-119
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• 2012

섬유염색산업 중 면섬유의 염색과정에서 발생되는 머서라이징 폐액은 폐수처리장의 pH(수소이온농도)를 올리는 주원인이 되고 있어, 높은 pH에 따른 폐수처리 부과금이나 황산을 이용한 폐수 중화에 사용되는 약품비용이 과다하게 소요되고 있으며, 머서라이징공정에 사용되는 약품인 가성소다 비용이 계속 증가하고 있어, 기업의 환경처리비용 및 약품소모비용에 대한 부담이 매우 큰 실정이다. 본 기술은 머서라이징 폐액에 멤브레인 공정에 적용하여 폐가성소다로부터 가성소다를 회수할 뿐만 아니라, 회수된 가성소다를 다시 머서라이징 공정에 재이용할 수 있도록 하여 약품 절감효과 뿐만 아니라 폐수의 발생량과 오염물질의 농도의 획기적인 저감이 가능한 것이다. 본 연구에서는 서로 다른 기공크기를 갖는 막을 적용하여 투과플럭스, 부피회수율, 부유물질 및 유기물 제거율, 가성소다회수율, 파울링지수 등을 고려하여 폐수 특성에 맞는 가장 적합한 막을 선정하고, 각각의 막에 대하여 온도조건, 압력조건, 화학세정 등의 운전변수를 최적화, 고효율 폐알카리 회수 장치의 경제성 및 기술적 타당성 평가를 통한 가성소다 회수공정을 구성하였다.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.959-970
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• 2000

A laboratory-scale experiment was conducted to investigate the effect of soluble microbial products(SMP) on permeate flux in the submerged membrane separation activated sludge process. Continuous and batch filtration test were operated to understand mechanism of relationship between membrane fouling and SMP. Synthetic wastewater(phenol) was used as a carbon source. Hydraulic retention time(HRT) and mixed-liquor volatile suspended solids(MLVSS) of the reactor were kept at 12 hours and 9.000mg VSS/L, respectively. Batch filtration tests ($J_{60}/J_o$) using the mixed liquor from reactor showed that the increase of accumulated SMP concentration in the reactor caused to the decreasing permeate flux and the increasing of the adhesion matters which form cake and gel layer. The resistance value of cake layer was measured $2.9{\times}10^{10}{\sim}4.0{\times}10^{10}(1/m)$, this value showed more significant effect on flux drop than that of among other resistance layers. Batch phenol-degradation experiment was conducted to observe SMP type expected $SMP_{nd}$ and $SMP_{e}$ (SMP resulted from endogenous cell decomposition), these are non-biodegradable high molecular weight organic matter and playa significant role in permeate flux drop. Also, SMP concentration was accumulated as increased of HRT against flux drop.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.34-41
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• 2016

Using UF-SWRO hybrid process, pre-blending tests of seawater and brackish water were performed to investigate the effects on removal of boron and humic acid (HA). Feedwater pre-blending was set based on TDS concentration from 15,000 mg/L to 27,000 mg/L and analyzed for boron removal characteristics. Also organics rejection at same TDS concentration range was investigated by injecting HA. Boron concentration appeared to be high as TDS concentration was high ranging from 76.60% to 83.27%, but boron concentration in final produced water was increased up to 0.69 mg/L from 0.48 mg/L. In cases of HA tests at 10 mg/L, 22,500 mg/L TDS appeared to be higher removal rate of 17.59% than a very poor result of 8.43% in 27,000 mg/L. But high HA removal rate of 57.14% was obtained in produced water with 22,500 mg/L TDS containing 10 mg/L of HA and 27,000 mg/L TDS yielded lower boron removal rate of 54.49%. Meanwhile it was found that a relatively high flux and recovery rate were obtained following process when feedwater was injected with HA. It is considered that most of fouling substances were eliminated by binding between HA and $Ca^{2+}$. Thus, when desalination using UF-SWRO with respect to boron and HA, TDS concentration is determined to be advantageous as lower.

• Membrane Journal
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• v.28 no.4
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• pp.252-259
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• 2018

An acidic, real metal-plating wastewater was treated by a fluidized bed membrane reactor introduced with granular activated carbon (GAC) as fluidized media. With GAC fluidization, there was no increase in suction pressure with time at each flux set-point applied. At neutral solution pH, much less fouling rate was observed than acidic pH under GAC fluidization. Higher solution pH resulted in the increase in particle size in metal-finishing wastewater, thus producing a less dense cake structure on membrane. More than 95% of chemical oxygen demand was observed from the fluidized bed membrane reactor under GAC fluidization. Total suspended solid concentration in membrane permeate was near zero. At the raw wastewater pH, no removal of copper and chromium by the fluidized bed membrane reactor was observed. As the pH was increased to 7.0, removal efficiency of copper and chromium was increased considerably to 99 and 94%, respectively. Regardless of solution pH tested, more than 95% of cyanide was removed possibly due to the strong adsorption of organic-cyanide complex on GAC in fluidized bed membrane reactor.