• 상하수도학회지
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• 제31권6호
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• pp.501-510
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• 2017

In this study, it is estimated that ceramic membrane process which can operate stably in harsh conditions replacing existing organic membrane connected with coagulation, sedimentation etc.. Jar-test was conducted by using artificial raw water containing kaolin and humic acid. It was observed that coagulant (A-PAC, 10.6%) 4mg/l is the optimal dose. As a results of evaluation of membrane single filtration process (A), coagulation-membrane filtration process (B) and coagulation-sedimentation-membrane filtration process (C), TMP variation is stable regardless of in Flux $2m^3/m^2{\cdot}day$. But in Flux $5m^3/m^2{\cdot}day$, it show change of 1-89.3 kpa by process. TMP of process (B) and (C) is increased 11.8, 0.6 kpa each. But, the (A) showed the greatest change of TMP. When evaluate (A) and (C) in Flux $10m^3/m^2{\cdot}day$, TMP of (A) stopped operation being exceeded 120 kpa in 20 minutes. On the other hand, TMP of (C) is increased only 3 kpa in 120 minutes. Through this, membrane filtration process can be operated stably by using the linkage between the pretreatment process and the ceramic membrane filtration process. Turbidity of treated water remained under 0.1 NTU regardless of flux condition and DOC and $UV_{254}$ showed a removal rate of 65-85%, 95% more each at process connected with pretreatment. Physical cleaning was carried out using water and air of 500kpa to show the recovery of pollutants formed on membrane surface by filtration. In (A) process, TMP has increased rapidly and decreased the recovery by physical cleaning as the flux rises. This means that contamination on membrane surface is irreversible fouling difficult to recover by using physical cleaning. Process (B) and (C) are observed high recovery rate of 60% more in high flux and especially recovery rate of process (B) is the highest at 95.8%. This can be judged that the coagulation flocs in the raw water formed cake layer with irreversible fouling and are favorable to physical cleaning. As a result of estimation, observe that ceramic membrane filtration connected with pretreatment improves efficiency of filtration and recovery rate of physical cleaning. And ceramic membrane which is possible to operate in the higher flux than organic membrane can be reduce the area of water purification facilities and secure a stable quantity of water by connecting the ceramic membrane with pretreatment process.

• 유기물자원화
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• 제24권3호
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• pp.35-43
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• 2016

하수처리장에서 배출되는 잉여슬러지 감량율을 증가시키기 위해 사용된 전처리 가용화시설에서, 가용화율에 따른 COD 성상변화를 살펴보았다. 대상하수처리장의 농축 잉여슬러지에 포함되어 있는 난분해성 COD는 총 COD의 37.0 % 이었다. 전처리 가용화시설에서 배출되는 잉여슬러지의 COD 세부성상 변화를 살펴보면 가용화율(5%, 10%, 20%, 30%, 35%)의 증가에 따라 고형성 생분해성 COD는 점차적인 감소를 보이고 있으며 이로 인한 용존성 생분해성 COD와 고형성 난분해성 COD가 증가하는 것을 볼 수 있었다. 잉여슬러지를 가용화하기 위하여 물리적 전처리시설을 적용할 때 생물학적 2차처리시설의 SRT가 상대적으로 길게 운영되면 잉여슬러지의 고형성 난분해성 COD의 함유율이 높고 상대적으로 고형성 생분해성 COD 농도가 낮게 된다. 고형성 생분해성 COD가 상대적으로 낮은 잉여슬러지의 경우 전처리 시설에 의한 가용화의 효과가 당초 예상보다 낮아질 수 있으므로, 가용화하여 혐기성 소화 할 경우 잉여슬러지에 대한 COD 성상 조사가 요구된다. 가용화율 5%에서 혐기성소화조에서의 COD 제거율은 2.1% 증가하였고, 가용화율 35%에서는 COD 제거율이 15.1% 증가 되었다. 전처리 시설에서 잉여슬러지 고형성 COD를 35% 가용화하였을 때 혐기성소화조에서의 COD 제거율은 25%에서 40%로 향상되었고 메탄가스발생량은 $607m^3$/일에서 $907m^3$/일으로 증가하는 것으로 나타났다.

• 대한환경공학회지
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• 제28권6호
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• pp.613-619
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• 2006

[ $MIEX^{(R)}$ ]와 응집에 의한 분자량 크기별 제거특성에서는 10 kDa 미만의 유기물질에 대해서는 $MIEX^{(R)}$ 처리가 우수한 제거능을 나타내었으나, 10 kDa 이상의 유기물질은 응집 공정에서 높은 제거능을 가지는 것으로 나타났다. 막의 공극 크기에 대한 투과 flux 실험결과 UF 공정에 비하여 MF 공정에서의 투과 flux 감소율이 낮게 나타나고 있으며, MF 공정에 적용된 전처리 공정중 $MIEX^{(R)}+MF$ 공정의 경우 응집+MF 공정에 비하여 투과 flux 감소율이 낮게 나타나고 있다. $MIEX^{(R)}+UF$ 공정의 경우 입자상 물질의 존재 유무에 상관없이 flux 감소율은 거의 유사하게 나타났으나, 응집+UF 공정의 경우에는 용존성 유기물질만이 존재하는 시수에 비하여 입자상 물질이 존재하는 경우 투과 flux 감소율은 작게 나타났다. 응집 공정의 적용 후 다양한 입도분포 변화가 발생하였으며, pH 7에서 $MIEX^{(R)}$ 입자의 제타전위 측정결과 $MIEX^{(R)}$ 입자의 전하는 평균 -2.3 mV로 나타나 전기화학적으로 입자상 물질의 흡착이 가능하며 $MIEX^{(R)}$가 침전됨에 따라 입자상 물질이 sweep되어 입도분포 변화를 보였다.

• Journal of Ecology and Environment
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• 제41권7호
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• pp.191-201
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• 2017

Background: Limited availability of corn stover due to the competing uses (organic manure, animal feed, bio-materials, and bioenergy) presents a major concern for its future in the bio-economy. Furthermore, biomass research has exhibited different results due to the differences in the supply of enzymes and dissimilar analytical methods. The effect of the two leading pretreatment techniques (dilute acid and alkaline) on glucose yield from three corn stover fractions (cob, stalk, and leaf) sourced from a single harvest in Uganda were studied at temperatures 100, 120, 140, and $160^{\circ}C$ over reaction times of 5, 10, 30, and 60 min. Results: From this study, the highest glucose concentrations obtained from the dilute acid (DA) pretreated cobs, stalks, and leaves were 18.4 g/L (66.8% glucose yield), 16.2 g/L (64.1% glucose yield), and 11.0 g/L (49.5% glucose yield), respectively. The optimal pretreatment settings needed to obtain these yields from the DA pretreated samples were at a temperature of $160^{\circ}C$ over an incubation time of 30 min. The highest glucose concentrations obtained from the alkaline (AL) pretreated cobs, stalks, and leaves were 24.7 g/L (81.73% glucose yield), 21.3 g/L (81.23% glucose yield), and 15.0 g/L (51.92% glucose yield), respectively. To be able to achieve these yields, the optimal pretreatment settings for the cobs and stalks were $140^{\circ}C$ and for a retention time of 30 min, while the leaves require optimal conditions of $140^{\circ}C$ and for a retention time of 60 min. Conclusions: The study recommends that the leaves could be left on the field during harvesting since the recovery of glucose from the pretreated cobs and stalks is higher.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.520-520
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• 2009

Organic by-products derived from cellulose and lignin during organosolv pretreatments of yellow poplar wood (Liriodendron tulipifera) in the presence of $H_2SO_4$ and NaOH as catalysts, respectively, were subjected to various analyses to elucidate their effects on further performance of biological ethanol fermentation and provide preliminary data for the structure and utilization of organosolv lignin. Monomeric sugars amounted to ca. 2.2-7.7% in the organosoluble fraction of the organosolv pretreatment with $H_2SO_4$, while significantly low amount of sugars (0.2-0.3%) were determined in that of the organosolv pretreatment with NaOH. In case of addition of $H_2SO_4$ during organosolv pretreatment of biomass, a fermentation of the organosoluble fraction could be considered as an essential process to increase an efficiency of biomass utilization as well as yield of bioethanol. Precipitates, insoluble by-products in the solvent mixture, were also cficiency oed by diverse analytical methods and revealed that these were typically composed of a lignin moiety regardless of catalyst. According to the results of nuclear magnetic resonance (NMR), Fourier Tcinsform Infrared Spectroscopy (FT-IR) and Gel permeation chromatograp r (GPC), the main components of precipitates seem to be lignin polymers. However, their structures could be slightly modified during pretreatment and mixed with some carbohydrates by chemical bonds and/or physical associations.

• 공업화학
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• 제18권6호
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• pp.552-556
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• 2007

연구에서는 $TiO_2$ 담체에 귀금속(Pd, Ru, Ir)을 담지시켜 촉매를 제조하였다. 금속분산의 향상을 위해 $H_2O-H_2$ 전처리 기술이 이용되었고, 반응물로서 xylene, toluene 그리고 MEK를 사용하였다. 단일금속과 합금금속의 촉매들은 함침법에 의해 준비하였고, XRD, XPS 분석을 통하여 특성 분석하였다. Pd-Ru, Pd-Ir 촉매는 다양한 활성점을 나타내었고, 그것은 Pd의 metal 영역를 강화시켰다. 합금금속으로 이루어진 촉매가 단일 금속으로 이루어진 촉매에 비해 VOCs 전환율이 더 높았다. $H_2O-H_2$ 전처리 기술은 Pd 입자를 고르게 분산시켰다. 이는 촉매의 효율을 증진시키는 효과를 보여주었다. 본 연구에서 Pd에 소량의 Ru, Ir 첨가는 VOCs의 산화반응을 증진시켰고, $TiO_2$ 담체상에서 $H_2O-H_2$ 전처리는 VOCs의 제거효율을 증진시켰다.

• Membrane and Water Treatment
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• 제11권3호
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• pp.179-187
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• 2020

Electrodialysis has been applied for treatment of industrial wastewater including metal electroplating. The wastewater from metal plating industries contains high concentrations of inorganics such as copper, nickel, and sodium. The ions in the feed were separated due to the electrical forces in the electrodialysis. The concentrate compartment is exposed to the elevated concentrations of the ions and yielded inorganic precipitations on the cation exchange membranes. The presence of organic matter in the metal plating wastewater affects complex interfacial reactions, which determines characteristics of inorganic scale fouling. The wastewater from a metal plating industry in practice was collected and the inorganic and organic compositions of the wastewater were analyzed. The performance of electrodialysis of the raw wastewater was evaluated and the effects of adjusting pH of the raw water were also measured. The integrated processes with neutralization and electrodialysis showed great removal of heavy metals sufficient to discharge to aquatic ecosystem. The organic matter in the raw water was also reduced by the neutralization, which might enhance removal performance and alleviate organic fouling in the integrated system.

• 상하수도학회지
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• 제24권2호
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• pp.237-246
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• 2010

This study was carried out to compare the performances of hydrophobic and hydrophilic membranes in the filtration of the pretreatment waters using coagulants such as PAC and PAHCs, and to investigate the influence of NOM characteristics on the fouling of membranes. As a result, the hydrophobic fraction was more effectively removed by PAHCs, however the transphilic and hydrophilic fraction were more effectively removed by PAC on NOM removal. Raw water showed the highest response in the range of humic substances, and pre-coagulated waters with PAC and PAHCs followed. It was also observed that the fouling effect for a hydrophobic membrane was greater than that of a hydrophilic membrane with a similar pore size, due to fouling caused by adsorption. Foulants causing significant flux decline were alcoholic compounds (polysaccharide-like) and humic substances including aromatic groups. Especially, it appeared that alcoholic compounds such as polysaccharide-like substances which mostly remained after coagulation pretreatment had most influence on fouling. It was found that fouling were influenced by each fraction NOM components depending on coagulants used. And PAHCs was more efficient for membrane fouling than PAC.

• 상하수도학회지
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• 제24권6호
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• pp.735-741
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• 2010

A pilot test was carried out to investigate the long term operation characteristics of Microfiltration (MF) system as a pretreatment for seawater reverse osmosis (SWRO) processes for two years. A commercialized MF module with pressurized operation type was used to filter seawater to remove particles which can foul reverse osmosis (RO) membrane. Silt Density Index (SDI) values of filtered seawater by the MF system were ranged from 0.14 to 1.79, which meet the SDI standard for RO feed water as depicted in previous literatures. Although the tested seawater is quite clean (i.e., dissolved organic cabon (DOC) concentration and turbidity were about 1 mg/l and less than 1 NTU, respectively) enough not to foul the MF membrane, steep increase in trans-membrane pressure (TMP) with a constant flux were observed over a whole operation period. A set of operation and water analysis data implies that the steep increase in TMP was resulted from iron and maganese fouling by the combination of metal corrosion by seawater and oxidation state by aeration and residual chlorine.

• 한국환경과학회지
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• 제20권6호
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• pp.767-773
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• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.