• 유기물자원화
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• 제20권3호
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• pp.83-88
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• 2012

부영양화로 인한 조류의 과도한 번식은 하천과 호수의 수질에 심각한 문제를 야기하고 있다. 따라서 하천과 호수의 수질 오염 방지를 위해서는 물리화학적 또는 생물학적 처리를 통해 효과적인 조류 제거가 필요하다. 본 연구에서는 전기부상과 혐기성 수소 발효 공정의 연계를 통해 효과적인 조류 제거와 에너지를 생산하고자 하였다. Chlorophyll a를 기준으로 전기부상에 의한 조류 제거효율은 전류 증가에 따라 증가하였으며 최대 95.9%로 나타났다. 제거된 조류로부터 에너지를 회수하기 위하여 혐기성 수소 발효 타당성을 조사하였다. 조류와 초음파로 전처리를 수행한 조류의 최종 수소 수율은 각각 17.3및 61.1ml $H_2/g$ dcw(dry cell weight)로 나타났다. 조류의 초음파 전처리는 가수분해 속도를 증가시켜 최대 수소 수율을 3.4배 향상시키는 것으로 나타났다.

• 상하수도학회지
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• 제17권4호
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• pp.534-541
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• 2003

Membrane processes are now frequently considered for application in drinking water treatment. The biggest impediment for applying membrane processes is fouling that comes from mass flux (such as particle and organic matter) to the membrane surface and its pores due to convection flow through the membrane. Natural organic matter (NOM) has been reported as the most detrimental foulant. Some research also indicated that particles were often the dominant cause of fouling. Therefore, both NOM and particle fouling need to be examined to better understand fouling in ultrafiltration. Two waters from natural sources, Lake Austin water and Missouri River water, were selected. Both waters are relatively hard waters but has significantly different particle concentrations, which will elucidate effects of particles on membrane fouling. Precipitative softening is traditionally designed to remove hardness ions in hard waters but it can also remove particles and organic matter. Therefore, the integrated water treatment with softening and ultrafiltration is proposed as a promising option for hard waters. The three levels of softening were used to represent different degrees of pretreatment to ultrafiltration in terms of organic matter (i.e., NOM fouling) and precipitates (i.e., particle fouling by further precipitation). Results showed that natural particles in Missouri River water was detrimental foulants of ultrafiltration. As the levels of softening were increased, NOM and particle removal was increased, and thus fouling was decreased. Direct images of the surface of the membranes by scanning electron microscopy allowed observation of the different properties of particles caught in fibril networks of natural organic matter.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.54-60
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• 2006

In this paper, we describe a bio-fluidic device for adaptive sample pretreatment, in order to optimize the conditions under which absorbance assays can be conducted. This device can be successfully applied to the measurement of Escherichia coli (E. coli) concentrations using adaptive dilution, with which the dilution ratio can be adjusted during the dilution. Although many attempts have been previously made to miniaturize complex biochemical analyses at the chip scale, very few sample pretreatment processes have actually been miniaturized or automated at this point. Due to the lack of currently available on-chip pretreatments, analytical instruments tend to suffer from a limited range of analysis. This occasionally hinders the direct and quantitative analysis of specific analyses obtained from real samples. In order to overcome these issues, we exploit two novel strategies: dilution with a programmable ratio, and to-and-fro mixing. The bio-fluidic device consists of a rectangular chamber constructed of poly(dimethylsiloxane) (PDMS). This chamber has four openings, an inlet, an outlet, an air control, and an air vent. Each of the dilution cycles is comprised of four steps: detection, liquid drain, buffer injection, and to-and-fro mixing. When using adaptive sample pretreatment, the range in which E. coli concentrations can be measured is broadened, to an optical density (O.D.) range of $0.3{\sim}30$. This device may prove useful in the on-line monitoring of cell concentrations, in both fermenter and aqueous environments.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.58-64
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• 2008

Pretreatment of eliminating FFA is needed to make biodiesel from animal fat recovered from leather wastes because its acid value is high. This study was carried out to investigate the influence of 4 different pretreatment methods, which are heterogeneous catalyst method, ion exchange resin method, low pressure.high temperature method, and alkali method on the eliminating FFA and fatty acid composition. The results showed that the rate of eliminating FFA increased in the order of alkali method > catalyst method > low pressure high temperature method > ion exchange method. In the case of pretreatment of alkali method using NaOH, the rate of eliminating FFA appeared more than 86% regardless of acid value. Therefore, it was considered that alkali method using NaOH was the most effective in the view of economical and productive aspects, taking it into account that the acid value of animal fat recovered from fleshing scrap generated during leather making processes was 7 to 8.

• Environmental Engineering Research
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• 제23권2호
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• pp.159-163
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• 2018

The feasibility of applying coagulation-integrated microfiltration (MF) as a pretreatment for an ultrafiltration (UF) feed in oily wastewater treatment was investigated. The effects of different coagulants on oil removal rates from wastewater were studied. The maximum oil removal rate of 82% was obtained after coagulation with 130 mg/L of polyaluminium chloride (PAC). UF flux reached $95L/(m^2{\cdot}h)$ with coagulation-integrated MF as pretreatment. This value was 2.5 times higher than that flux obtained without pretreatment. The value of UF flux increased as the transmembrane pressure (TMP) and cross-flow velocity (CFV) of the UF module increased. UF flux gradually increased when TMP and CFV exceeded 0.4 MPa and 3 m/s, respectively, because of concentration polarization and membrane fouling stabilization. Chemical oxygen demand reduction and oil removal rate reached 95.2% and 98.5%, respectively, during integrated membrane processing with a PAC concentration of 130 mg/L, TMP of 0.4 MPa, and CFV of 3 m/s for UF. In addition, sequentially cleaning the fouling membrane with NaOH and $HNO_3$ aqueous solutions caused UF flux to recover to 90%. These encouraging results suggested that the hybrid integrated membrane process-based coagulation and MF + UF are effective approaches for oily wastewater treatment.

• 한국재료학회지
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• 제11권9호
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• pp.802-809
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• 2001

Electroplating is an attractive alternative deposition method for copper with the need for a conformal and conductive seed layer In addition, the Cu seed layer should be highly pure so as not to compromise the effective resistivity of the filled copper interconnect structure. This seed layer requires low electrical resistivity, low levels of impurities, smooth interface, good adhesion to the barrier metal and low thickness concurrent with coherence for ensuring void-free fill. The electrical conductivity of the surface plays an important role in formation of initial Cu nuclei, Cu nucleation is much easier on the substrate with higher electrical conductivities. It is also known that the nucleation processes of Cu are very sensitive to surface condition. In this study, copper seed layers deposited by magnetron sputtering onto a tantalum nitride barrier layer were used for electroplating copper in the forward pulsed mode. Prior to electroplating a copper film, the Cu seed layer was cleaned by plasma H$_2$ and $N_2$. In the plasma treatment exposure tome was varied from 1 to 20 min and plasma power from 20 to 140W. Effects of plasma pretreatment to Cu seed/Tantalum nitride (TaN)/borophosphosilicate glass (BPSG) samples on electroplating of copper (Cu) films were investigated.

• 한국표면공학회지
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• 제57권1호
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• pp.1-7
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• 2024

The study investigated the impact of substrate pretreatment on depositing high-quality B-doped diamond (BDD) thin films using the HFCVD method. Films were deposited on Si and Nb substrates after sanding and seeding. Despite identical sanding conditions, BDD films formed faster on Nb due to even diamond seed distribution. Post-deposition, film average roughness (R_a) remained similar to substrate R_a, but higher substrate R_a led to decreased crystallinity. Nb substrate with 0.83 ㎛ R_a exhibited faster crystal growth due to dense, evenly distributed diamond seeds. BDD film on Nb with 0.83 ㎛ R_a showed a wide, stable potential window (2.8 eV) in CV results and a prominent 1332 cm^-1 diamond peak in R_aman spectroscopy, indicating high quality. The findings underscore the critical role of substrate pretreatment in achieving high-quality BDD film fabrication, crucial for applications demanding robust p-type semiconductors with superior electrical properties.

• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.622-633
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• 2024

For quality standardization, the application of functional lactic acid bacteria (LAB) as starter cultures for food fermentation is a well-known method in the fermented food industry. This study assessed the effect of adding a non-thermally microbial inactivated starter culture to kimchi, a traditional Korean food, in standardizing its quality. In this study, pretreatment based on sterilization processes, namely, slightly acidic electrolyzed water (SAEW) disinfection and ultraviolet C light-emitting diode (UVC-LED) of raw and subsidiary kimchi materials were used to reduce the initial microorganisms in them, thereby increasing the efficiency and value of the kimchi LAB starter during fermentation. Pretreatment sterilization effectively suppressed microorganisms that threatened the sanitary value and quality of kimchi. In addition, pretreatment based on sterilization effectively reduced the number of initial microbial colonies in kimchi, creating an environment in which kimchi LAB starters could settle or dominate, compared to non-sterilized kimchi. These differences in the initial microbial composition following the sterilization process and the addition of kimchi LAB starters led to differences in the metabolites that positively affect the taste and flavor of kimchi. The combined processing technology used in our study, that is, pre-sterilization and LAB addition, may be a powerful approach for kimchi quality standardization.

• KSBB Journal
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• 제27권2호
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• pp.86-90
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• 2012

Ethanol fermentations were carried out using simultaneous saccharification and fermentation (SSF) and separated hydrolysis and fermentation (SHF) processes with monosaccharides from seaweed, Saccharina japonica (sea tangle, Dasima) as the biomass. The pretreatment was carried out by thermal acid hydrolysis with $H_2SO_4$ or HCl. Optimal pretreatment condition was determined at 10% (w/v) seaweed slurry with 37.5 mM $H_2SO_4$ at $121^{\circ}C$ for 60 min. To increase the yield of saccharfication, isolated marine bacteria Bacillus sp. JS-1 was used and 48 g/L of reducing sugar were produced. Ethanol fermentation was performed using SSF and SHF process with Pachysolen tannophilus KCTC 7937. The ethanol concentration was 6.5 g/L by SSF and 6.0 g/L by SHF.

• Membrane and Water Treatment
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• 제3권4호
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• pp.211-219
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• 2012

To enhance the efficiency of water treatment and reduce the extent of membrane fouling, the membrane separation process is frequently preceded by other physico-chemical processes. One of them might be ion exchange. The aim of this work was to compare the efficiency of natural organic matter removal achieved with various anion-exchange resins, and to verify their potential use in water treatment prior to the ultrafiltration process involving a ceramic membrane. The use of ion exchange prior to ceramic membrane ultrafiltration enhanced final water quality. The most effective was MIEX, which removed significant amounts of the VHA, SHA and CHA fractions. Separation of uncharged fractions was poor with all the resins examined. Water pretreatment involving an ion-exchange resin failed to reduce membrane fouling, which was higher than that observed in unpretreated water. This finding is to be attributed to the uncharged NOM fractions and small resin particles that persisted in the water.