• Bulletin of the Korean Chemical Society
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• 제15권9호
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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.

• 분석과학
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• 제26권6호
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• pp.375-380
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• 2013

본 연구에서는 암석과 퇴적물 시료를 대상으로 이플루오린화 암모늄을 이용한 시료 분해법을 적용하여 open vessel digestion 후 유도결합 플라즈마 질량분석법(Inductively coupled plasma mass spectrometry, ICP/MS)으로 게르마늄을 분석하였다. 미국 지질조사소 표준물질 중 QLO-1, SDO-1을 사용하였고, 실제 시료로 GeoPT용 퇴적물, 현무암, 점토를 사용하였다. 휘발하여 손실되기 쉬운 것으로 알려진 게르마늄을 이플루오린화 암모늄($NH_4HF_2$) 시료 분해법을 사용함으로서 게르마늄 휘발 억제와 동시에 암석 및 퇴적물을 open vessel digestion하에서 간단하고 빠르게 분해 가능하였으며, 또한 이플루오린화 암모늄 분해법에 과산화수소를 함께 사용해도 게르마늄의 회수율에 영향을 끼치지 않았다. ICP/MS에 의한 게르마늄 분석 결과, MDL (method detection limit)은 0.015 ${\mu}g/g$, 게르마늄 회수율은 106~128% 이었다.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1513-1518
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• 2017

Anaerobic mono- and co-digestion of sewage sludge and food waste leachate (FWL) were performed by assessing methane production and characterizing microbial communities. Anaerobic digestion (AD) of waste activated sludge (WAS) alone produced the lowest methane ($281ml\;CH_4$), but an approximately 80% increase in methane production was achieved via co-digestion of WAS and FWL ($506ml\;CH_4$). There were less differences in the diversity of bacterial communities in anaerobic digesters, while archaeal (ARC) and bacterial (BAC) amounts reflected AD performance. Compared with the total ARC and BAC amounts in the mono-digestion of WAS, the ARC and BAC amounts increased two and three times, respectively, during co-digestion of FWL and WAS. In characterized archaeal communities, the dominant ratio of hydrogenotrophic methanogens in the mono-digestion of WAS approached nearly a 1:1 ratio of the two acetoclastic and hydrogenotrophic methanogens in the co-digestion of FWL and WAS. The ARC/BAC ratio in the digesters varied in the range of 5.9% to 9.1%, indicating a positive correlation with the methane production of AD.

• 대한토목학회논문집
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• 제7권3호
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• pp.1-11
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• 1987

중온소화(中溫消化)와 고온소화(高溫消化)의 차이점을 보다 명확히 규명하기 위하여 소화(消化)의 정지(停止)를 포함하는 폭넓은 실험을 행하였다. 연구결과, 정상소화(正常消化)와 소화조해(消化阻害)를 구분짓는 한계체류시간(限界滯留時間)이 존재하여, 중온(中溫)에서는 10일(日), 고온(高溫)에서는 5일(日)부근이었고 그 이하(以下)의 체류시간(滯留時間)에서는 소화(消化)의 조해(阻害)가 급격하게 발생하였는데 고온(高溫)에 비하여 중온(中溫)에서의 조해(阻害)정도가 매우 컸다. 중온소화(中溫消化)의 한계체류시간이상(限界滯留時間以上)에서는 소화(消化)상태가 거의 유사하였으나, 그이하(以下)의 체류시간(滯留時間)에서는 고온소화(高溫消化)가 월등히 양호(良好)하였으며, 고온(高溫)에서는 중온(中溫)에 비하여 소화(消化)슬러지발생량(發生量)이 감소하는 동시에 소화(消化)슬러지의 침강속도(沈降速度)가 크게 증가하고 여과비저항(濾過比抵抗)은 감소하였다. 한편 반응속도(反應速度)는 소화(消化)에 마치는 온도(溫度)와 체류시간(滯留時間)의 영향을 나타내는 데 유효하였다. 또한 온도(溫度)에 관계없이 반응속도(反應速度)가 증가함에 따라 가스발생속도(發生速度)가 선형적(線形的)으로 증가하였고 그 상관관계(相關關係)는 중온(中溫)과 고온(高溫)에서 거의 일치하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권11호
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• pp.1659-1676
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• 2002

Ruminant animals develop a diverse and sophisticated microbial ecosystem for digesting fibrous feedstuffs. Plant cell walls are complex and their structures are not fully understood, but it is generally believed that the chemical properties of some plant cell wall compounds and the cross-linked three-dimensional matrix of polysaccharides, lignin and phenolic compounds limit digestion of cell wall polysaccharides by ruminal microbes. Three adaptive strategies have been identified in the ruminal ecosystem for degrading plant cell walls: production of the full slate of enzymes required to cleave the numerous bonds within cell walls; attachment and colonization of feed particles; and synergetic interactions among ruminal species. Nonetheless, digestion of fibrous feeds remains incomplete, and numerous research attempts have been made to increase this extent of digestion. Exogenous fibrolytic enzymes (EFE) have been used successfully in monogastric animal production for some time. The possibility of adapting EFE as feed additives for ruminants is under intensive study. To date, animal responses to EFE supplements have varied greatly due to differences in enzyme source, application method, and types of diets and livestock. Currently available information suggests delivery of EFE by applying them to feed offers the best chance to increase ruminal digestion. The general tendency of EFE to increase rate, but not extent, of fibre digestion indicates that the products currently on the market for ruminants may not be introducing novel enzyme activities into the rumen. Recent research suggests that cleavage of esterified linkages (e.g., acetylesterase, ferulic acid esterase) within the plant cell wall matrix may be the key to increasing the extent of cell wall digestion in the rumen. Thus, a crucial ingredient in an effective enzyme additive for ruminants may be an as yet undetermined esterase that may not be included, quantified or listed in the majority of available enzyme preparations. Identifying these pivotal enzyme(s) and using biotechnology to enhance their production is necessary for long term improvements in feed digestion using EFE. Pretreating fibrous feeds with alkali in addition to EFE also shows promise for improving the efficacy of enzyme supplements.

• 한국식품영양학회지
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• 제15권1호
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• pp.29-35
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• 2002

단체급식소 12개소의 식단을 수거하여 각 메뉴별 및 1인분식단별NA함량을 분석하였고 인공소화 기법을 활용하며 체내에서 생성 가능한NA의 함량을 예측하였다. 육류와 어패류를 주재료로 요리된 메뉴들의 인공소화 전.후NA 함량을 분석한 결과 멸치볶음에서 NDMA 함량이 흔적량~4.87$\mu\textrm{g}$/kg으로 가장 높았고, 채소류를 주재료로 한 메뉴들에서는 불검출에서 흔적량의 NDMA가 정량되었으며, 인공소화 후에도 흔적 량 이하로 정량되었다 1인 분량의 식사를 수거하여 인공소화 전 . 후의 NA를 분석한 결과NDMA는 인공소화 전 0.20~0.78$\mu\textrm{g}$/kg의 범위였으나 인공소화 후 에는 0.43~0.80$\mu\textrm{g}$/kg으로 약간 증가하였다. 상기의 분석 결과를 기초로 하여 성인 1일 NA섭취량을 계산한 결과 0.60~2.34$\mu\textrm{g}$/day/person이며, 인공소화를 통한 체내에서의 생성량을 고려하면 최대 5.15$\mu\textrm{g}$/day/ person으로 추정된다.

• 대한토목학회논문집
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• 제26권1B호
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• pp.113-118
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• 2006

간헐포기방식의 슬러지 소화 기술에 대한 비용을 분석하였다. 포기비율은 간헐포기소화의 가장 중요한 설계인자이며, 포기 비율에 따라 시설비와 동력비가 달라진다. 목표 SS 제거율을 35%로 설정하고, 철근콘크리트형식의 SBR 간헐포기소화조를 설계하였으며, 이로부터 시설비와 동력비를 산출하였다. 비용 평가는 할인율과 경제성장율을 고려하는 현재가치로 환산하는 방법을 사용하였다. 포기비율이 낮은 경우는 시설비가 높지만 동력비는 적게 소요되며, 포기비율이 높으면 반대로 시설비는 낮지만 동력비는 증가한다. 초기시설비는 호기성 소화가 간헐포기소화보다 더 저렴하다. 그러나, 총비용면에서 내용연수 약 10년 이상의 운전에서는 간헐포기소화가 호기성 소화보다 더 유리하다. 특히, 내용연수가 길수록 최적 포기비율은 낮아지며, 내용연수가 45년 정도일 때 최적포기비율은 0.3 정도이고, 이 경우 총비용은 호기성소화의 64% 수준이다.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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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.

• Food Science and Biotechnology
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• 제17권1호
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• pp.180-183
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• 2008

Digestion properties of 3 types of cereals, white rice, brown rice, and barley, were measured after cooking or grinding. Regardless of the processing methods, white rice showed the highest rate and the greatest extent of digestion, whereas barley showed the lowest values. During the early digestion period, cooked white rice kernels had a larger k (kinetic constant) value than uncooked white rice flour, indicating that cooking induced faster digestion than grinding. In the case of brown rice and barley, the cell wall in cooked kernels remained intact and resulted in a lower k values than those of uncooked flour. However, after 3 hr of digestion, the total digestion extent was greater for the cooked brown rice and barley than that for uncooked flours. The high content of slowly digestible starch (SDS) in cooked brown rice and barley might be due to the starch fraction which was protected by the cell wall. The resistant starch (RS) content, however, was greater for the uncooked flours than that for cooked kernels. The cooked kernels of 3 cereal samples tested showed higher glycemic index (GI) values than the uncooked flours.

• 상하수도학회지
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• 제31권1호
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• pp.13-19
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• 2017

Relatively low efficiency in anaerobic digestion process is mainly caused by unproper mixing method. In this study, tray motion type agitator was applied in actual anaerobic digestion tank in order to improve the digestion efficiency, equalize the flow velocity distribution and energy saving. The impeller of tray motion type agitator was reciprocated vertically. Gas lift type agitator and tray motion type agitator appears almost same mixing efficiency include digestion rates. However, tray motion type agitator have shown that lower energy consumption compared to the conventional gas lift type agitator. Implementation of tray motion type agitator in the anaerobic digestion tanks contributed to the stabilization of mixing environment, efficiency and energy efficiency of the tank.