• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.243-245
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• 2002

Brackish water desalination using reverse osmosis(RO) membrane is more useful and economic than sea water to solve the shortage of fresh water supply because of its low total dissolved solid(TDS) contents. Silica and humic acid in brackish water make serious fouling problems and cause the decline of permeate flux and increase of operating pressure. In this study, the experiments for removal of silica and humic acid were conducted with calcite particles to prevent membrane fouling and investigated the effect of pH of feed water Adsorption of silica to calcite was higher at pH=7.5 than 9.5 and removal rate was increased according to increase of initial concentration of silica. The effect of pH on adsorption of humic acid was not significant but at low initial concentration the adsorption of humic acid was enhanced at pH 7.5. The result of this study expect to apply to brackish water desalination experiment of flat-sheet reverse osmosis membrane.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 춘계 총회 및 학술발표회
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• pp.115-118
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• 1999

• Environmental Engineering Research
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• 제16권3호
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• pp.149-157
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• 2011

Nanofiltration (NF) experiments were conducted to investigate fouling of Al-hydroxide precipitate and the influence of organic compound, inorganic compound, and their combination, i.e., multiple foulants. $CaCl_2$ and $MgSO_4$ were employed as surrogates of inorganic compounds while humic acid was used as surrogate of organic compound. The flux attained from NF experiments was fitted with the mathematical fouling model to evaluate the potential fouling mechanisms. Al-hydroxide fouling with a cake formation mechanism had little effect on the NF membrane fouling regardless of the Al concentration. The NF fouling by Al-hydroxide precipitate was deteriorated in presence of inorganic matter. The effect of Mg was more critical in increasing the fouling than Ca. This is because the Mg ions enhanced the resistances of the cake layer accumulated by the Al-hydroxide precipitate on the membrane surfaces. However, the fouling with Mg was dramatically mitigated by adding humic acid. It is interesting to observe that the removal of the conductivity was enhanced to 61.2% in presence of Mg and humic acid from 30.9% with Al-hydroxide alone. The influence of dissolved matter (i.e., colloids) was more negative than particulate matter on the NF fouling for Al-hydroxide precipitate in presence of inorganic and organic matter.

• Korean Membrane Journal
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• 제11권1호
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• pp.21-28
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• 2009

We investigated the effect of organic materials on membrane fouling in advanced drinking water treatment by a hybrid module packed with granular activated carbon (GAC) outside multi-channel ceramic microfiltration membrane. Synthetic water was prepared with humic acid and kaolin to simulate natural water resouces consisting of natural organic matter and inorganic particles. Kaolin concentration was fixed at 30 mg/L and humic acid was changed as 2~10 mg/L to inspect the effect of organic matters. Periodic back-flushing using permeate water was performed for 10 sec per filtration of 10 min. As a result, both resistance of membrane fouling (Rf) and permeate flux (J) were influenced highly by concentration of humic acid. It proved that NOM like humic acid could be an important factor on membrane fouling in drinking water treatment. Turbidity and UV254 absorbance were removed up to above 97.4% and 59.2% respectively.

• 한국물환경학회지
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• 제22권1호
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• pp.140-144
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• 2006

This study was performed to investigate the effect of organic characteristics and feed water solution chemistry on membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). Specifically, Aldrich humic acids (AHA) and Suwannee river humic acids (SHA) were used in SDI/MFI experiments. Higher SDI values were observed with increasing organic concentration. AHA with larger molecular weight (MW) and SUVA (${\approx}UV_{254}/TOC$) resulted in higher SDI values, compared to SHA. The feed solution chemistry (i.e, pH, ionic strength, and hardness) also affects SDI values to some degree. In particular, SDI increased with increasing hardness ($Ca^{2+}$) concentration for AHA. Unlike SDI, the MFI developed on the basis of particle cake filtration theory, was not accurately assessed due to internal fouling by organics such as pore adsorption and subsequent pore blocking.

• 상하수도학회지
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• 제30권6호
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• pp.737-744
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• 2016

The investigation of effects on fouling propensity with various viscosity of feed solutions would be better understanding for forward osmosis (FO) performance since the fouling propensity was directly influenced with solution viscosity. Therefore, this study was focused on the FO fouling with model foultants (humic acid, alginate) by altering solution viscosity with change of ionic strength (I.S) and $Ca^{2+}$ concentrations. In the comparison between humic acid and alginate, as expected, the alginate generally caused more severe fouling (almost 35.8 % of flux reduction) based on the solution characteristics (high viscosity) and fouling patterns (coil and gel layer). However, interesting point to note is that the fouling propensity of alginate was more severe even though it was applied with low viscosity of feed conditions (I.S = 20 mM, $Ca^{2+}=1mM$). This might be due to that crossed linked gel layer of alginate on the FO membrane surface could be best formed in the condition of $Ca^{2+}$ presence and higher I.S, and that is more dominant to fouling propensity than the low viscosity of feed solutions.

• 멤브레인
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• 제15권1호
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• pp.34-43
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• 2005

Poly(vinyl alcohol) (PVA)이 폴리술폰 한외여과 막, 술폰화된 폴리에테르술폰, 폴리아미드 나노 막 위에 코팅된 나노 복합막을 가압법에 의해서 제조되었다. PVA는 글루터알데하이드 수용액으로 가교되었다. 모든 지지층위에 PVA 희박용액이 성공적으로 코팅되어 나노복합막이 제조되었다. 지지막 위의 친수화도가 높아짐에 따라 수투과 유량이 증가하였다. 특히 음하전을 띠는 폴리아미드 나노 복합막의 제타전위는 PVA로 코팅함으로서 감소되었다. 막 오염 실험은 양이온을 띠는 계면활성제, 휴민산, 휴민산과 칼슘이온 복합체 및 bovine serum albumin을 사용하여 실행하였다. PVA로 코팅되지 않은 폴리아미드 나노복합막은 각각의 오염물질에 의해서 심하게 오염되었다. 휴민산과 단백질에 의한 오염은 오염물질의 등전점에서 가장 심하게 발생하였다. 휴민산에 이가 양이온을 첨가함으로서 오염이 심각하게 일어났다. PVA 수용액으로 폴리아미드 나노 복합막을 코팅함으로서 막 오염이 감소되었다. PVA로 코팅된 폴리아미드 나노 복합막은 산, 염기용액에 대해 저항성을 보였다.

• 멤브레인
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• 제29권5호
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• pp.276-283
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• 2019

본 논문에서는 축전식 탈염 공정에서 파울링 현상의 확인과 파울링의 제거공정 조건을 확립하는 연구를 진행하였다. 공급액에 첨가된 파울링 유발 물질인 Humic acid sodium salt (HA)의 농도는 5, 10, 15 mg/L이었다. 주어진 일반의 흡/탈착 조건에서 파울링의 발생은 시간이 지남에 따라 흡착과 탈착 농도의 증가로 확인할 수 있었다. 파울링 현상을 제거하기 위해 흡착 및 탈착에서의 전압과 시간을 변경하였다. 이로부터 흡착 조건 1.2 V/5 min, 탈착 조건 -3 V/2 min에서 파울링 제거를 확인하였다.

• 대한환경공학회지
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• 제27권9호
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• pp.965-969
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• 2005

이온교환막 공정의 중요한 운전인자인 전류밀도와 전해질의 pH가 막 오염에 미치는 영향을 연구하였다. 휴믹산 100 mg/L를 포함하고 있는 NaCl 용액에서 Neosepta AMX (Tokuyama Soda, Japan) 음이온교환막의 막 오염 현상을 관찰하였다. 한계전류밀도(LCD) 전 후 영역의 전류를 공급하면서 이온교환막의 전기저항 변화를 측정하여 막 오염 현상을 분석하였다. 실험결과 LCD 이하에서는 전류밀도의 변화가 막 오염에 큰 영향을 미치지 않았다. 그러나 LCD 이상의 전류밀도에서는 막 오염이 심각하게 진행되는 것으로 나타났다. 실험 후 휴믹산에 오염된 막에 대한 전류전압 곡선에서도 LCD 이상에서 실험한 경우에 막 오염으로 전기저항이 증가하고 LCD가 감소한 것을 알 수 있었다. 또한 휴믹산이 포함된 전해질 용액의 pH를 산성 조건으로 조정한 후 실험한 결과 pH가 감소할수록 막 오염이 증가하는 것으로 나타났다. 이 결과로부터 막 오염이 휴믹산의 표면 전하에 의한 것보다 물리화학적 성질에 더 큰 영향을 받는다는 것을 알 수 있었다.

• 상하수도학회지
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• 제18권1호
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• pp.73-80
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• 2004

This study investigated the phenomena of membrane fouling by NOM and the effect of the fouling on removal of micro-pollutants. NOM has a great effect on decline of permeate flux. Permeate flow rate was reduced by 88% in RO and 34.8% in NF for 323hr operation period. Removal rate of $UV_{254}$, is 87.4% in RO and 78.5% in NF and removal rate of DOC is 42.7% in RO and 32.9% in NF for 2mg/l humic acid. Removal efficiency of the micro-pollutants by the RO and NF membranes fouled by humic acid was mostly lower than that by the new membrane. The concentration polarization which affects the flux and the rejection was thought to occur in the active layer of the membrane, as the membrane was getting fouled.