• Membrane and Water Treatment
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• 제3권3호
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• pp.141-149
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• 2012

The aeration provided in a Submerged Membrane Bioreactor (SMBR) improves membrane filtration by creating turbulence on the membrane surface and reducing membrane resistance. However, conventional hollow fiber membrane modules are generally packed in a vertical orientation which limits membrane scouring efficiency, especially when aeration is provided in the axial direction. In the present research, 3 innovative hollow-fiber membrane modules, each with a different membrane orientation, were developed to improve membrane scouring efficiency and enhance permeate flux. Pilot testing was performed to investigate the permeate flux versus time relationship over a 7-day period under different intermittent modes. The results indicated that the best module experienced an overall permeate flux decline of 3.3% after 7 days; the other two modules declined by 13.3% and 18.3%. The lower percentage of permeate flux decline indicated that permeate productivity could be sustained for a longer period of time. As a result, the operational costs associated with membrane cleaning and membrane replacement could be reduced over the lifespan of the module.

• 한국막학회:학술대회논문집
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• 한국막학회 1993년도 추계 총회 및 학술발표회
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• pp.68-73
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• 1993

여과포에 의한 분진 포집기술은 다른 분진포집기술에 비해 가장 우수한 집진성능을 나타낼수 있는 집진기술로서 최근에 와서는 분진발생공정, 연소설비 및 폐기물 소각설비의 중금속 물질, 유해 기체 및 분진의 동시포집 적용 등 광범위한 산업분야에 적응되어 운전되고 있다. 배출기체의 악조건과 습도가 다량 함유된 조건에서는 여과포 집진장치의 적용이 어렵다고 생각되고 있지만, 처리 기체의 조건 및 포집분진의 특성에 적합한 여과포의 개발과 탈진방식(cleaning method)의 개선으로 인해 해결이 가능하게 되었다. 또한 여과포에 의한 분진포집기술은 장치를 통과하는 배출기체의 속도가 다른 집진기술에 비해 느려 여과포 면적이 상대적으로 넓어져서 장치의 설치면적이 많이 소요된다는 단점이 있으나, 여과포를 원간으로 봉재하여 서로 접근시켜 많은 갯수를 다단으로 배치함과 동시에 연속탈진시스템(on-line cleaning)을 채택함으로써 장치에 소요되는 면적을 최소한으로 줄이려는 연구가 계속되고 있다. 대체적으로 여과포에 의한 분진포집기술의 산업체 적용에서 장치의 압력손실은 약 100 - 100 $mmH_2O$ 정도의 범위가 대부분이고 분진 포집효율은 거의 99.9%에서 99.99% 정도 달성이 가능하다[1,2,3].

• Membrane and Water Treatment
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• 제13권4호
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• pp.191-199
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• 2022

In industrial production, the development of traditional polyamide nanofiltration (NF) membrane was limited due to its poor oxidation resistance, complex preparation process and high cost. In this study, a composite NF membrane with high flux, high separation performance, high oxidation resistance and simple process preparation was prepared by the method of dilute solution dip coating. And the sulfonated polysulfone was used for dip coating. The results indicated that the concentration of glycerin, the pore size of the based membrane, the composition of the coating solution, and the post-treatment process had important effects on the structure and performance of the composite NF membrane. The composite NF membrane prepared without glycerol protecting based membrane had a low flux, when the concentration of glycerin increased from 5% to 15%, the pure water flux of the composite NF membrane increased from 46.4 LMH to 108.2 LMH, and the salt rejection rate did not change much. By optimizing the coating system, the rejection rate of Na₂SO₄ and PEG1000 was higher than 90%, the pure water flux was higher than 40 LMH (60psi), and it can withstand 20,000 ppm.h NaClO solution cleaning. When the post treatment processes was adjusted, the salt rejection rate of NaCl solution (250 ppm) reached 45.5%, and the flux reached 62.2 LMH.

• Membrane and Water Treatment
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• 제8권2호
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• pp.185-199
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• 2017

Low-pressure membrane filtration is increasingly used for tertiary treatment of wastewater effluent organic matter (EfOM), mainly comprising organic base/neutral compounds. In-line coagulation with underdosing, charge neutralization, and sweep floc conditions prior to ultrafiltration (UF) was studied to determine removals of the EfOM components and consequent reduction of fouling using polyethersulfone membranes. Coagulation and UF substantially reduced fouling for all coagulation conditions while removing from 7 to 38% of EfOM organic acids. From 7 to 16% of EfOM organic base/neutrals were removed at neutral pH but there was no significant removal for slightly acid coagulation conditions even though fouling was substantially reduced. Sweep floc produced the lowest resistance to filtration but may be inappropriate for in-line use due to the large added volume of solids. Charge-neutralization resulted in poor recovery of the initial flux with hydraulic cleaning. Under-dosing paralleled sweep floc in reducing hydraulic resistance to filtration (for sub-critical flux) and the initial flux was also easily recovered with hydraulic cleaning. Hydrophobic and hydrophilic base/neutrals were identified on the fouled membranes but as previously reported the extent of fouling was not correlated with accumulation of organic base/neutrals.

• Membrane and Water Treatment
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• 제3권1호
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• pp.35-49
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• 2012

In membrane processes, various agents are used to enhance, protect, and recover membrane performance. Applying these agents in membrane modification could potentially be considered as a simple method to improve membrane performance without additional process. Citric acid (CI) and sodium bisulfite (SB) are two chemicals that are widely used in membrane feed water pretreatment and cleaning processes. In this work, preadsorptions of CI and SB were developed as simple methods for polysulfone ultrafiltration membrane modification. It was found that hydrogen bonding and Van Der Waals attraction could be responsible for the adsorptions of CI and SB onto membranes, respectively. After modification with CI or SB, the membrane surfaces became more hydrophilic. Membrane permeability improved when modified by SB while decreased a little when modified by CI. The modified membranes had an increase in PEG and BSA rejections and better antifouling properties with higher flux recovery ratios during filtration of a complex pharmaceutical wastewater. Moreover, membrane chlorine tolerance was elevated after modification with either agent, as shown by the mechanical property measurements.

• 멤브레인
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• 제26권4호
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• pp.273-280
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• 2016

가압형 정삼투(pressure-assisted forward osmosis, PAFO) 공정은 기존의 정삼투(forward osmosis, FO) 공정의 단점인 낮은 수투과도 및 유도용질의 역확산을 극복하여 전체 공정 효율을 향상시킨다. 하지만 가압에 의한 추가적인 수리학적 압력의 작용은 파울링을 가속화 시킨다는 단점이 있다. 본 연구는 PAFO의 간헐적 운전방법인 간헐적 가압형 정삼투(Intermittent pressure-assisted forward osmosis, I-PAFO)의 파울링 저감 가능성을 평가하기 위해 수행되었다. 비교를 위해 FO 및 PAFO를 동시에 운전하여, 세 가지 운전에서의 파울링 거동을 관찰하였다. 파울링 실험을 위한 오염물질로 콜로이드 실리카 입자를 사용하였고, 분리막 및 입자의 정전기적 상호작용 에너지 변화가 파울링 거동에 미치는 영향도 확인하였다. 실험결과, I-PAFO 운전에서, 용액 pH 변화에 관계없이 가압구간, 압력완화 구간에서 각각 PAFO, FO보다 높은 수투과도를 유지하였다. 파울링 실험 후, PAFO에 비해 I-PAFO운전에서 더 적은 수투과도 감소가 관찰되었고, 이로 인해 물리세정 후 향상된 수투과도 회복률 또한 관찰되었다.

• 청정기술
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• 제7권3호
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• pp.179-185
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• 2001

각종 전처리 필터로 사용되는 정밀여과막은 국내의 경우 대부분 수입에 의존하고 있다. 몇몇 회사에서 개발을 시도하고 있지만, 막에 대한 특성 파악이나 공극제어등과 같은 문제를 해결하는데 많은 어려움이 있다. 따라서 본 연구에서는 A 사에서 개발한 정밀여과막을 이용하여 한강원수와 시수에 대하여 RO 유입전 전처리 필터로서의 적합성을 판단하고자 본 연구를 수행하였다. 한강원수는 총 2회에 걸쳐서 실험을 실시하였다. 적정 공급수 압력은 0.2~0.4 기압이며 여과수의 탁도는 0.4 NTU를 나타냈다. 플럭스는 $6,000{\sim}9,000L/m^2/hr$ 였다. 시수의 경우 회수율을 90%로 운전시 안정된 플럭스와 탁도를 나타내었다. 화학세정 후 TMP의 증가율은 감소를 하였으며, 탁도는 0.4 NTU에서 0.1 NTU로 개선되었다.

• 상하수도학회지
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• 제34권2호
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• pp.93-104
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• 2020

As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling. were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.

• 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.

• 상하수도학회지
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• 제32권5호
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• pp.453-460
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• 2018

The impact of sodium hydroxide, which is one of chemicals of clean in place (CIP) for removing membrane fouling, on the PVDF membrane is reviewed with respect to physical/chemical structural change, the permeability affected therefrom. Based on the cleaning concentration applied in membrane water treatment facilities, 10% of accumulated defluorination was confirmed up to 166g.hr/L which reflects the exposure time. However, membrane resistance was confirmed to be reduced by about 10%. Through FT-IR and EDS analysis, reduction of F and change of are confirmed as factors that affect the permeability of membrane. Membrane resistance, which affects permeability, is affected by loss of additives for hydrophilicity, rather than defluorination of PVDF material. Therefore, in order to check membrane degradation degree, an accelerated test by NaOH was carried out, loss of additives was confirmed, and then PVDF inherent characteristic was observed.