• Environmental Engineering Research
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• 제20권3호
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• pp.223-229
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• 2015

The application of coagulation for feed water pretreatment prior to microfiltration (MF) process has been widely adopted to alleviate fouling due to particles and organic matters in feed water. However, the efficiency of coagulation pretreatment for MF is sensitive to its operation conditions such as pH and coagulant dose. Moreover, the optimum coagulation condition for MF process is different from that for rapid sand filtration in conventional drinking water treatment. In this study, the use of response surface methodology (RSM) was attempted to determine coagulation conditions optimized for pretreatment of MF. The center-united experimental design was used to quantify the effects of coagulant dose and pH on the control of fouling control as well as the removal organic matters. A MF membrane (SDI Samsung, Korea) made of polyvinylidene fluoride (PVDF) was used for the filtration experiments. Poly aluminum chloride (PAC) was used as the coagulant and a series of jar tests were conducted under various conditions. The flux was $90L/m^2-h$ and the fouling rate were calculated in each condition. As a result of this study, an empirical model was derived to explore the optimized conditions for coagulant dose and pH for minimization of the fouling rate. This model also allowed the prediction of the efficiency of the coagulation efficiency. The experimental results were in good agreement with the predictions, suggesting that RSM has potential as a practical method for modeling the coagulation pretreatment for MF.

• 에너지공학
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• 제7권1호
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• pp.57-64
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• 1998

폴리에스터와 스테인레스스틸섬유를 재료로 제조된 제전사여과포에 대한 물리화학적 특성시험 및 여과포성능 기초시험을 수행하였다. 실험용먼지로 제철.제강, 시멘트제조, 열공급시설 및 폐기물공정에서 채취된 먼지를 처리하여 사용하였다. 제전사여과포의 물리화학적 특성 실험에서는 산성분위기하에서 인장강도 및 초기탄성계수변화를 조사하였고, Automated Permporometer를 이용하여 평균흐름세공압력, 기포점 세공지름, 평균흐름세공지름 및 세공크기분포를 구하였다. 또한 벤처규모의 여과포 기초성능 시험장치를 이용하여 먼지부하에 따른 압력손실, 먼지통과율 및 여과포성능 평가지표를 산출하였다. 산성가스 및 분위기하에서 제전사여과포의 인장강도는 온도 및 노출시간과 깊은 관련이 있었다. 압력손실은 여과속도와 먼지부하가 증가함에 따라 증가하였으며 증가형태는 먼지의 종류에 따라 달랐다. 먼지 통과율은 먼지종류에 관계없이 먼지부하의 증가에 따라 급격히 감소하는 경향을 나타내었다. 여과포성능지표는 먼지 포집 초기에는 증가했다가 급격히 감소하여 일정하게 유지되었다.

• 한국물환경학회지
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• 제18권3호
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• pp.253-260
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• 2002

The purpose of this research was to describe the mechanisms and prevention of initial degradation in turbidity of the sand filter effluent. The method used was by adding a coagulant (PAC) to the sand filter after backwashing as a means of reducing turbidity. It was found that adding 80 mg/L of PAC solution to the sand filter was very effective in improving the initial effluent turbidity. A turbidity removal efficiency of 99 % was observed in the initial term period as compared to a 70% efficiency without PAC addition. The PAC solution added to the sand filter resulted in high aluminum concentration at the upper layer as compared with the bottom layer of the sand filter column. A change in the zeta potential to a strong positive-ions at upper layer was observed at this time but only a small change was obtained at the bottom. This result showed that the zeta potential of the sand was changed to positive with PAC coating. The effect of pH on zeta potential with PAC addition was also investigated. Zeta potential was greatly changed to positive-ion at pH 4~6. A series of experiments was then conducted in this study to optimize the pH of the PAC solution to be added to the sand filter after backwashing. The removal efficiency of turbidity was found to be highest at pH 5. This result suggested that hydrolyzed aluminium species attached to the surface of the sand enhanced the removal of turbidity of the effluent.

• The Korean Journal of Physiology
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• 제20권2호
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• pp.225-235
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• 1986

가토 근위세뇨관에서 Percoll gradient에 의해 분리한 기저막소포(basolateral membrane vesicle)에서 PAH 이동에 미치는 여러 음이온들의 영향을 rapid filtration technique을 이용하여 관찰하였다. NA-dependent PAH 축적은 용액내 $SO_4$와 $SSO_3$에 의하여 유의하게 억제되었으나 $Cl,\;SCN,\;HPO_4,\;acetate$ 및 oxalate에 의해서는 영향을 받지 않았다. 용액내의 $SO_4$는 상경적으로 PHA 이동을 억제하였다. 소포내 음이온을 부하시킨 후 PAH 이동을 측정했을 때 $acetate,\;SO_4$ 및 PAH의 부하에 의해 PAH 이동은 유의하게 증가되었으며, 소포내 부하되는 $SO_4$농도가 증가함에 따라 PAH 축적은 증가되었다. $SO_4$에 의한 PAH의 trans-stimulation은 Na 농도 경사 존재시 더욱 증가되었으며 이들은 2 mM probenecid 및 1mM SITS에 의해 억제되었다. 이들 결과들은 신피질세뇨관 세포의 기저막에 PAH/음이온 교환에 의해 PAH가 이동되는 기전이 존재한다는 것을 가르킨다. 그러나 PAH 이동에 영향이 없는 음이온들은 PAH/음이온 교환에 기질로써 작용하지 않기 때문인지 아니면 이들 음이온들의 높은 투과성에 인해 나타난 결과인지는 더욱 추구해 보아야 확인될 것으로 생각된다.

• 한국식품위생안전성학회지
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• 제31권1호
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• pp.21-27
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• 2016

본 연구에서는 V. parahaemolyticus를 신속정확하게 고감도로 검출하기 위해 단클론성 항체를 개발하고 이를 이용하여 일반적인 효소면역분석법(ELISA)과 효소면역분석법의 낮은 민감도를 보완할 수 있는 면역선택여과법(ISF)을 개발하여 민감도 및 효율성을 비교분석 하였다. 먼저 heat killed V. parahaemolyticus (HKVP)를 준비하여 7주령 BALB/c mouse에 면역한 후 세포융합 및 클로닝을 통해 HKVP 4H9-9번 및 16번 2종의 hybridoma cell을 확보하였다. Western blot을 통해 보다 특이성이 높은 것으로 확인된 HKVP 4H9-9번 항체를 대량 생산정제하여 분석법을 확립한 결과 검출한계가 ID-ELISA법은 $10^6cell/mL$, ISF 법은 $5{\times}10^1cell/mL$로 나타나 ISF법의 민감도가 매우 높은 것으로 확인되었다. 분석효율성은 ID-ELISA법의 경우 분석을 위해 9단계의 과정을 거쳐 총 16시간의 분석시간이 소요된 반면, ISF법의 경우 3단계의 과정을 거쳐 1시간 이내에 분석을 완료할 수 있는 것으로 확인되었다. 교차반응성의 경우 두 분석법 모두 일부 Vibrio spp. (IDELISA법: V. alginolyticus, ISF법: V. vulnificus)과 S. aureus에 반응성이 있는 것으로 확인되었지만 V. parahaemolyticus에 보다 강한 반응성을 나타내었기 때문에 V. parahaemolyticus에 특이적인 분석법인 것으로 확인되었다. 특히 ISF법은 ELISA법 보다 민감도가 높고 분석에 소요되는 시간도 짧아 V. parahaemolyticus를 신속하게 분석하는데 활용이 가능할 것으로 판단된다.

• 상하수도학회지
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• 제23권4호
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• pp.459-469
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• 2009

It is well known that coagulation pretreatment can reduce foulants prior to membrane filtration. The purpose of this research was to investigate the effects of coagulation on fouling of ceramic microfiltration membrane($0.1 {\mu}m$) using pilot plant of $150m^3/day/train$ capacity. Train A membrane system has pretreatment process of ozonation and coagulation while train B has only coagulation. Two types of coagulation operation were investigated: back mixer(rapid mixing with or without slow mixing) which is a conventional mechanically stirred mixer and an inline static mixer. Ozone dose rate for train A was 1 mg/L and ozone contact time was 12 min. The coagulation dose(PACl 10% as $Al_2O_3$) rate was changed 20~40 mg/L according to experimental schedule. In this experimental conditions, the coagulation of back mixer type with rapid mixing(GT=72,000) and slow mixing(GT=45,000) was the best effective in reduction of ceramic membrane fouling regardless preozonation. Especially, the effect of inline static mixer was sensitive to change in water quality. Ozonation mainly affected irreversible fouling rather than reversible fouling in accordance with less adsorption of NOM on the membrane surface. Thus, the increase rate of the nomalized TMP(trans membrane pressure) at $25^{\circ}C$ for train A was relatively lower than that of train B under same coagulation process with same coagulant dosage. The best performance of ceramic membrane appeared in case of combined process with ozonation, therefore this integrated process is able to archive less coagulant dosing and secure a stability of ceramic membrane system.

• 상하수도학회지
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• 제20권1호
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• pp.27-34
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• 2006

This study was conducted to evaluate the performance of a membrane bioreactor filled with high concentration of powdered activated carbon (HCPAC-MBR) to reduce DBPs at the drinking water treatment. The pilot system was installed after the rapid sand filtration process whose plant was the conventional treatment process. The removal efficiencies of DBPs were measured during pilot operation period of 2 years. HAA and THM removal rates could be maintained around 80~90% without any troubles and then tremendous reduction of HAA and THM reactivity were observed more than 52%. The average removal rate of HAA formation potential (FP) and THM formation potential (FP) were 70.5% and 67.6% respectively. It is clear that the PAC membrane bioreactor is highly applicable for advanced water treatment to control DBPs.

• Journal of Pharmaceutical Investigation
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• 제24권3호spc1호
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• pp.11-18
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• 1994

We have studied the iron uptake by the purified brush-border membrane vesicles (BBMVs) to determine the effect of fructose on the absorption of iron. BBMVs were prepared by the modified calcium precipitation method, The degree of purification was routinely assessed by the marker enzyme, alkaline phosphatase, and the functional integrity was tested by $D-[1-^3H]glucose$ uptake. The appearance of membrane vesicles was shown by transmission electron microscopy (TEM). The uptakes of complexes of labeled iron $[^{59}Fe]$ with fructose and ascorbate were measured with a rapid filtration technique, The uptake rate and pattern of the two iron-complexes, Fe(III)-fructose and Fe(III)-ascorbate, were also observed. A typical overshooting uptake of D-glucose was observed with peak value of $2{\sim}3$ times higher concentration than that at equilibrium. This result was similar to other studies with BBMVs. TEM showed that the size of BBMVs was uniform and we can hardly find any contaminants, Fe(III)-fructose has the higher value of $V_{max}$ and the lower value of Km than those of Fe(III)-ascorbate, respectively. It may be concluded that D-fructose is more effective in promoting the iron absorption than ascorbate.

• 멤브레인
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• 제1권1호
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• pp.100-100
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• 1991

A novel system to thicken the concentrated colloidal solution from membrane water treat-ment processes was developed. A hollow-fiber microfilter(hydrophilic polyethylene nominal pore size 0.1 μm total surface area 0.42 m2) was installed in an acrylic housing that has an aeration port 5 cm below the membrane and a clarifier in the bottom. The concentrate was uniformly supplied from the top of the housing. Bacuum filtration caused downward flow of concentrate and as a result thickening interface. The addition of poly-aluminum chloride (PAC) resulted in rapid increase of trans-membrane pressure (TMP) and in no improvement of the filtered water turbidity and thickening process. Two types of con-centrate and concentrate turbidity had little effect on the increase of TMP and concentrate thickening. It was observed that for the same height of membrane housing membrane surface area to housing volume (A/V) ratio had significant effect on the increase of TMP. When the housing volume was increased ten times the increasing rate of TMP was three times faster as compared to the original housing. A hydraulic model successfully simulated the formation and sedimentation of thickening interface.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권2호
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• pp.134-139
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• 2006

Methanotrophs are microorganisms that possess the unique ability to utilize methane as their sole source of carbon and energy. A novel culture system, known as the compulsory circulation diffusion system, was developed for rapid growth of methanotrophic bacteria. Methanol dehydrogenase (MDH, EC 1.1.99.8) from Methylomicrobium sp. HG-1, which belongs to the type I group of methanotrophic bacteria, can catalyze the oxidation of methanol directly into formaldehyde. This enzyme was purified 8-fold to electrophoretic homogeneity by means of a 4 step procedure and was found in the soluble fraction. The relative molecular weight of the native enzyme was estimated by gel filtration to be 120 kDa. The enzyme consisted of two identical dimers which, in turn, consisted of large and small subunits in an ${\alpha}_2{\beta}_2$ conformation. The isoelectric point was 5.4. The enzymatic activity of purified MDH was optimum at pH 9.0 and $60^{\circ}C$, and remained stable at that temperature for 20 min. MDH was able to oxidize primary alcohols from methanol to octanol and formaldehyde.