• Journal of Microbiology and Biotechnology
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• 제19권1호
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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.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1993-2005
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• 2019

Thermophilic anaerobic digestion (TAD) is characterized by higher biogas production rates as a result of assumedly faster microbial metabolic conversion rates compared to mesophilic AD. It was hypothesized that the thermophilic microbiome with its lower diversity than the mesophilic one is more susceptible to disturbances introduced by alterations in the operating factors, as an example, the supply of nitrogen-rich feedstock such as poultry manure (PM). Laboratory scaled TAD experiments using cattle slurry and increasing amounts of PM were carried out to investigate the (in-) stability of the process performance caused by the accumulation of ammonium and ammonia with special emphasis on the microbial community structure and its dynamic variation. The results revealed that the moderate PM addition, i.e., 25% (vol/vol based on volatile substances) PM, resulted in a reorganization of the microbial community structure which was still working sufficiently. With 50% PM application, the microbial community was further stepwise re-organized and was able to compensate for the high cytotoxic ammonia contents only for a short time resulting in consequent process disturbance and final process failure. This study demonstrated the ability of the acclimated thermophilic microbial community to tolerate a certain amount of nitrogen-rich substrate.

• 한국폐기물자원순환학회지
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• 제34권2호
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• pp.140-147
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• 2017

This study was conducted to evaluate the effects of physical characteristics. Twelve specific odorous compounds and various sources of bacteria were tested via treatment of food waste using an ultra-thermophilic aerobic composting process. Food waste was mixed with seed material and operated for 47 days. During composting, the temperature was maintained at $80-90^{\circ}C$. The variations in $O_2$, $CO_2$ and $NH_3$ production suggested typical microorganism-driven organic decomposition patterns. After composting, the concentrations of 12 specific odorous compounds other than ammonia did not exceed the allowable exhaust limits for odor. After composting, thermophiles represented 50% of all bacteria. After composting, the percentage of thermophile bacterial increased by 15%. Therefore, both stable composting operation and economic benefit can be expected when an ultra-thermophilic composting process is applied to food waste.

• 상하수도학회지
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• 제26권1호
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• pp.21-27
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• 2012

This study evaluated the performance of a thermophilic two-phase anaerobic digestion (TTPAD) coupled with membrane process treating garbage leachate. The pilot-scale treatment system is consisted of thermophilic acidogenic reactor (TAR) and thermophilic methanogenic reactor (TMR) coupled with an ultrafiltration (UF) membrane unit. The hydraulic retention time of TAR and TMR were 4 and 20 days, respectively. Effluent TCOD and SCOD of the TTPAD were $25\;{\pm}\;6\;and\;12\;{\pm}\;3$ g/L, respectively, and the corresponding TCOD and SCOD removal efficiencies were 77% and 81%, respectively. Propionate was major acids as 75% in the effluent. Scum formation was not observed in TTPAD, which might be resulted from complete lipid degradation. However, TTPAD was appeared to be sensitive to free ammonia toxicity. The UF membrane was operated with constant pressure filtration at average TMP 1.3 atm. Permeate flux had a range of 15-30 $L/m^2/hr$. With UF membrane, TCOD removal increased from 77% to 93%, and this SS free effluent would be beneficial to subsequent processes such as ammonia stripping.

• 한국미생물·생명공학회지
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• 제25권6호
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• pp.623-629
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• 1997

The studies of isolation and physiological characteristics of mesophilic or thermophilic bacteria from thermophilic oxic process (TOP) treating Chinese restaurant wastes were conducted. Chinese restaurant wastes were consist of moisture; 75.8%, solids; 24.2% and ash; 0.49%. The volatile solid was about 99% of total dry solids. In wastes used in this experiment, there was content of crude protein; 4.47%, crude lipid; 3.56%, free sugar, 0.4% , crude starch; 10.34% and crude fiber 3.14%, respectively. And then it has about 4,970 kcal/kg-dry solid of Chinese restaurant wastes. From TOP treating the chinese restaurant wastes, 37 strains of mesophilic or thermophilic bacteria were primarily isolated using medium used for the isolation and among them 6 strains of thermophilic and 7 strains of mesophilic bacteria were selected by testing the activities of amylase, cellulase, protease and lipase. TB-1, TB-9 as thermophilic bacteria and MB-15-1, 15-2, MB23 as mesophilic bacteria having strong enzyme activity were selected among isolated strains. All selected strains reduced nitrate to nitrite and they utilized glucose, manose, manitol, and maltose as carbon source. From these MB15-2 was identified as Bacillus cereus, TB1, Bacillus licheniformis and TB9; Bacillus schlegelii.

• 유기물자원화
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• 제4권1호
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• pp.1-11
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• 1996

음식물 쓰레기의 고온 퇴비화 과정에서 종균 첨가가 미생물의 변화에 미치는 영향을 조사하였다. 실험실용 소형 퇴비화 장치에 선발한 고온성 세균, 효모 및 고온성 세균, 효모 복합종균을 첨가하여 $50^{\circ}C$에서 분해시키면서 고온성 세균과 효모의 생육 및 pH의 변화를 측정한 결과, 모든 실험구에서 효모가 우선적으로 생육하였으며 고온성 세균은 그보다 1일 또는 2일 후에 생육하였다. 종균으로 고온성 세균만 사용한 경우는 효과가 거의 없었으나 고온성 세균과 효모의 복합 종균을 첨가한 경우에는 고온성 세균의 생육이 현저히 촉진되었다. 특히 효모 종균을 단독으로 첨가한 경우에도 고온성 세균의 수가 반응 시작부터 급속히 증가하였다. 이러한 결과는 음식물 쓰레기의 분해시 고온성 세균의 증식에는 효모의 역할이 필수적인 것으로 나타났으며 그 이유는 효모가 세균의 생육을 저해하는 유기산을 제거하기 때문으로 밝혀졌다.

• 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.

• 상하수도학회지
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• 제24권2호
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• pp.203-210
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• 2010

The signification of calorie/water (C/W) ratio was investigated in the treatment of highly concentrated organic wastes by thermophilic oxic process (TOP). Swine waste was used in this study. When C/W ratio was 1.6, most of swine waste was decomposed and all water was evaporated in the 24-h injection cycle. To improve treatment efficiency of TOP treating swine waste, the effect of shortening the swine waste injection cycle was examined. The shortening of injection cycle was conducted to stimulate the activity of thermophilic bacteria. A high temperature in the reactor was maintained by shortening of the injection cycle. When the swine waste injection cycle was shortened, the C/W ratio was fixed at 1.6. As a result, by shortening the swine waste injection cycle from 24-h to 12 and 6-h, the maximum loading rate of swine waste per day could be improved 1.9 and 3.5 times, respectively.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.226-230
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• 2005

The microbial community during composting of gargage was analyzed using 16S rDNA PCR - DGCE (denaturing gradient gel electrophoresis). Pseudomonas spp. was found throughout the process, and thermophilic Bacillus spp. was dominated at the thermophilic stage. Six thermophilic bacteria were isolated and identified as B. caldoxylolyticus, B. thermoalkalophilus, and B. thermodenitrificans.

• Journal of Microbiology and Biotechnology
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• 제12권4호
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• pp.683-686
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• 2002

To achieve optimum operation of a thermophilic aerobic digestion (TAD) process for waste activated sludge (WAS), TAD experiments using Bacillus stearothermophilus (ATCC 31197) were carried out to investigate the optimum concentration of dissolved oxygen (DO). TAD reactors were operated at DO concentrations of 0, 1, 2, 3, 4, and 5 ppm, and the results showed that the WAS could be successfully degraded by a TAD system operated with a DO concentration of 1 ppm and above. When the TAD system with an optimum additive (2 mM Ca ion), selected from a previous study, and 1 ppm DO concentration were combined with a thermal pretreatment ($121^{\circ}C$, 10 min), the results exhibited upgraded total suspended solids and an enhanced protein degradation.