• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.469-474
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• 2000

In order to enhance the degradation efficiency of waste activated sludge (WAS) by thermophilic aerobic digestion, an ultrasonic pretreatment was examined. It was observed that ultrasonic pretreatment increased the solubilization of organic matter in the WAS and that the solubilization ratio of the organics increased during the first 30 min but did not extensively increase thereafter. Therefore, a pretreatment time of 30 min was determined to be the economical pretreatment time from the experimental results. From the digestion experiments, which was conducted using the WAS collected from an oil refinery plant in Inchon, Korea, investigating the effects of an ultrasonic pretreatment on thermophilic aerobic digestion, it was confirmed that the proposed ultrasonic pretreatment was effective at enhancing the release of the cellular components in WAS and the degradation of released components in the thermophilic aerobic digestion.

• Analytical Science and Technology
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• v.17 no.4
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• pp.363-367
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• 2004

A simple and convenient digestion method was developed for the determination of heavy metal in polyurethane sample using only nitric acid in open system without heating. This digestion method had prevented loss of volatile elements of Hg and As and reduced the pretreatment time for the sample digestion. The detection limit is lowered over 10 times than that of microwave digestion method. Recoveries in polyurethane material were 108% for As, 96 ~ 99% for Hg, 102 ~ 103% for Cr, 98 ~ 102% for Pb, 86 ~ 90% for Cd, and 90 ~ 93% for Cu.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.570-576
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• 2001

Thermophilic aerobic bacteria were applied in the degradation of industrial waste activated sludge (WAS) on a laboratory scale expreiment. The performance of digestion was estimated by measuring the reduction of total suspended solids (TSS), dissolved organic carbon (DOC), and total organic carbon (TOC). Among three strains of Bacillus stearothermophilus and three strains of Thermus species, B. stearothemophilus ATCC 31197 showed the best overall efficiency level for the degradation of industrial WAS, which was collected from a wastewater treatment plant in an oil refinery factory. Industrial WAS coul be successfully detraded in a batch digestion with ATCC 31197. The stability of the digestion process with ATCC 31197 was successfully verified by semi-continuous (fill-and-draw) digestion experiment. From the results of this study, it was shown that the thermophilic aerobic digestion process with ATCC 31197 could efficiently be applied to the degradation of industrial WAS.

• Bulletin of the Korean Chemical Society
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• v.15 no.9
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• pp.786-791
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• 1994

A simple and rapid sample pretreatment process necessary for determination of metal oxides in water was proposed. Samples were injected into the continuous-flow tube installed inside the microwave oven and the treated samples were cooled before entered to the Ion Chromatography (IC) or Inductively Coupled Plasma (ICP). By coupling this microwave digestion system with IC or ICP, a fully automatic analytical procedures may be easily established. In this study, two different types of digestion methods were considered; the open tubing method (OTM) and the restraint tubing method (RTM). The RTM was proved to be 3 times faster in digestion period and 10 times higher in detection range than the OTM. Validation of proposed sample digestion system was carried out by using an ICP. The results showed that both of continuous-flow methods, the OTM and the RTM were comparable in accuracies with the conventional batch-type vessel digestion method.

• Analytical Science and Technology
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• v.14 no.4
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• pp.324-330
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• 2001

For the analysis of S, P and Zn in lubricating oil, microwave digestion method was studied by using inductively coupled plasma-atomic emission spectrometry(ICP-AES). Lubricating oil was completely decomposed with nitric acid or a mixture of nitric acid and hydrogen peroxide using and closed microwave digestion system. Digestions are completed within 50 min, a factor of at least 3~4 times faster than for the conventional digestion. A gradual heating program operated by the pulsed mode was found suitable for decomposing the lubricating oil matrix safely. The proposed method of digestion gave relative standard deviations(RSD) less than 3% for the elements determined.

• Journal of Life Science
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• v.5 no.3
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• pp.126-136
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• 1995

The studies had been conducted to evaluate the grain processing effects for ruminants on starch digestion, body weight gain and feed efficiency since 1970. This research deals with experimental results on chemical structure, gelatinization, microbial starch digestion in rumen, intestinal starch digestion in rumen, roles of protozoa, intestinal starch digestion of bypass starch, limits to starch digestion in small intestine. The grain processing has different effects on digestion, weight gain and feed efficiency when different grain sources and contents is used, and the quality and quantity of roughage is different. The economical and efficient method of grain processing should be selected considering weight gain and feed efficiency enhancement than digestibility.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.599-604
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• 2011

In typical proteomic analysis, trypsin digestion is one of the most time-consuming steps. Conventional proteomic sample preparation methods use an overnight trypsin digestion method. In this study, we compared high-pressure cycling technology (PCT) during enzyme digestion for proteome analysis to the conventional method. We examined the effect of PCT on enzyme activity at temperatures of 25, 37, and $50^{\circ}C$. Although a fast digestion (1 h) was used for the standard protein mixture analysis, the PCT-assisted method with urea showed better results for protein sequence coverage and the number of peptides identified compared with the conventional method. There was no significant difference between temperatures for PCT-assisted digestion; however, we selected PCT-assisted digestion with urea at $25^{\circ}C$ as an optimized method for fast enzyme digestion, based on peptide carbamylation at these conditions. The optimized method was used for stem cell proteome analysis. We identified 233, 264 and 137 proteins using the conventional method with urea at $37^{\circ}C$ for 16h, the PCT-assisted digestion with urea at $25^{\circ}C$ for 1 h, and the non-PCT-assisted digestion with urea at $25^{\circ}C$ for 1 h, respectively. A comparison of these results suggests that PCT enhanced the enzyme digestion by permitting better access to cleavage sites on the proteins.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1527-1534
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• 2010

The conventional peptide modification process of guanidination, in which the amino groups of lysine residues are converted to guanidino groups using O-methylisourea to create more basic homoarginine residues, is often used to improve the signal intensity of lysine-containing peptides in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Here, we used three different protease enzymes (trypsin, Lys-C, and Glu-C) to evaluate the effects of guanidination on the MS signals of two enzymatically digested proteins. Horse heart myoglobin and bovine serum albumin were guanidinated either before or after digestion with trypsin, Lys-C, or Glu-C. The resulting peptides were subjected to MALDI-MS, and signal intensities and sequence coverage were systematically evaluated for each digest. Guanidination prior to Glu-C digestion improved sequence coverage for both proteins. For myoglobin, guanidination before enzymatic digestion with trypsin or Lys-C also enhanced sequence coverage, but guanidination after enzymatic digestion enhanced sequence coverage only with Lys-C. For albumin, guanidination either before or after Glu-C digestion increased sequence coverage, whereas pre- or post-digestion guanidination decreased sequence coverage with trypsin and Lys-C. The amino acid composition of a protein appears to be the major factor determining whether guanidination will enhance its MALDI-MS sequence coverage.

• Analytical Science and Technology
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• v.16 no.3
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• pp.212-217
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• 2003

The memory effect of silver and aqua regia in the vessel by their permeation was studied during the microwave digestion of samples under the operating conditions of high temperature and pressure. The extent of permeation in vessels with the solution containing silver 5 mg has been shown to be $0.97{\mu}g/mL$ for the digestion of $HNO_3$ solution and $0.47{\mu}g/mL$ for the digestion of oil sample under condition of MDS 180T program ($180^{\circ}C$, 220 psi).

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.93-98
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• 2009

The thermophilic aerobic digestion (TAD) process is recognized as an effective method for rapid waste activated sludge (WAS) degradation and the deactivation of pathogenic microorganisms. Yet, high energy costs due to heating and aeration have limited the commercialization of economical TAD processes. Previous research on autothermal thermophilic aerobic digestion (ATAD) has already reduced the heating cost. However, only a few studies have focused on reducing the aeration cost. Therefore, this study applied a two-step aeration control strategy to a fill-and-draw mode semicontinuous TAD process. The NADH-dependent fluorescence was monitored throughout the TAD experiment, and the aeration rate shifted according to the fluorescence intensity. As a result, the simple two-step aeration control operation achieved a 20.3% reduction in the total aeration, while maintaining an effective and stable operation. It is also expected that more savings can be achieved with a further reduction of the lower aeration rate or multisegmentation of the aeration rate.