• 신재생에너지
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• 제4권4호
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• pp.56-64
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• 2008

Anaerobic biodegradability (AB), which can be determined with the ultimate methane yield by the decomposition of organic materials, is one of the important parameters for the design and the operation of anaerobic digestion plant. In this study, Biochemical methane potential (BMP) test has been carried out to evaluate the methane yields of animal manures such as pig and cattle slurries, and different forage crops cultivated at the reclaimed tideland such as maize, sorghum, barley, rye, Italian ryegrass (IRG), rape, rush, and waste sludge produced from slaughterhouse wastewater treatment plant (SSWTP). In the ultimate methane yield and biodegradability of animal manure, those of pig slurry were 345 $mlCH_4/gVS_{fed}$ and 44.7% higher than 247 $mlCH_4/gVS_{fed}$ and 46.4% of cattle slurry (Cat. 2). The ultimate methane yield and biodegradability of spike-crop rye (Rye 1) were 442.36 $mlCH_4/gVS_{fed}$ and 86.5% the highest among different forage crops, those of the other forage crops ranged from 306.6 to 379 $mlCH_4/gVS_{fed}$ of methane yield with the AB having the range of about 60 to 77%. Therefore the forage crops could be used as a good substrate to increase the methane production and to improve the biodegradability in anaerobic co-digestion together with animal manure.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.141-141
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• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• 에너지공학
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• 제24권4호
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• pp.11-17
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• 2015

본 연구에서는 음식물류 폐기물 폐수(이하, 음폐수)를 이용하여 혐기성발효 시 부산물로 생성되는 메탄가스의 생산효율을 높이고자 산발효 전처리를 수행하였으며 전처리된 음폐수를 이용하여 BMP 실험을 통해 메탄생산량 증대를 위한 산발효 최적조건을 확인하고자 하였다. 산발효된 음폐수를 이용하여 BMP 실험을 진행한 결과 HRT 3일 조건에서 0.220 L/g VS의 가장 높은 메탄생산량을 확인하였으며, 초기 pH별 BMP실험에서는 pH 6에서 19,920 mg/L로 가장 높은 VFA와 Acetic acid/TVFA(76.2%)를 보였다. 이때 메탄생산은 약 10일 이내로 대부분 생산되어 일반적인 메탄발효(30일 이내)에 비해 약 1/3수준으로 단축됨을 확인하였다. 메탄생성량은 0.294 L/g VS로 대조군 대비 약 1.3배 높은 효율을 나타내었다.

• 대한환경공학회지
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• 제35권8호
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• pp.586-591
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• 2013

정제 질소가스 생산용 기체 분리막을 매립가스의 $CH_4$ 순도를 높이는데 활용하기 위한 연구를 수행하였다. 1단과 2단 분리막 모듈의 면적비는 1:6인 경우가 $CH_4$ 회수를 위해서 적절하였다. 분리막 장치 설치 후 총 249회에 걸쳐 실험을 하였으며, 투과율은 평균 $CH_4$ 28.4%, $CO_2$ 94.3%로서, 매립가스로부터 $CH_4$를 회수하는데 $N_2$ 분리막의 사용 가능성을 확인할 수 있었다. 다만, $N_2$ 투과율 역시 16.5%에 불과하였으며, 이에 따라 최종 정제된 LFG의 농도는 $CH_4$ 69.7%, $CO_2$ 4.3%, $N_2$ 26.0%이었다. 따라서 $CH_4$의 순도를 높이기 위해서는 매립장내 외기유입 억제를 통해 $N_2$ 농도를 적어도 2.0% 이내로 제한할 필요가 있었다.

• 한국물환경학회지
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• 제21권3호
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• pp.256-262
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• 2005

The purpose of this study is to investigate the performances of organic removal and methane recovery by using a full scale two-phase anaerobic system. The full scale two-phase anaerobic process was consists of an acidogenic anaerobic baffled reactor (ABR) and a methanognic upflow anaerobic sludge blanket (UASB) reactor. The volumes of acidogenic and methanogenic reactors were designed to $28.3m^3$ and $75.3m^3$. The two-phase anaerobic system represented 60-82% of COD removal efficiency when the influent COD concentration was in the range of 7,150 to 16,270 mg/L after screening (average concentration is 10,280 mg/L). After steady-state, the effluent COD concentration in the methanogenic reactor showed $2,740{\pm}330 mg/L$ by representing average COD removal efficiency was $71.4{\pm}8.1%$ when the operating temperature was in the range of $19-32^{\circ}C$. The effluent SCOD concentration was in the range of 2,000-3,000 mg/L at the steady state while the volatile fatty acid concentration was not detected in the effluent. Meanwhile, the COD removal efficiency in the acidogenic reactor showed less than 5%. The acidogenic reactor played key roles to reduce a shock-loading when periodic shock loading was applied and to acidify influent organics. Due to the high concentration of alkalinity and high pH in the effluent of the methanogenic reactor, over 80% of methane in the biogas was produced consistently. More than 70% of methane was recovered from theoretical methane production of TCOD removed in this research. The produced gas can be directly used as a heat source to increase the reactor temperature.

• Asian-Australasian Journal of Animal Sciences
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• 제27권11호
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• pp.1652-1662
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• 2014

The present study investigated the optimum blending condition of protected fat, choline and yeast culture for lowering of rumen temperature. The Box Benken experimental design, a fractional factorial arrangement, and response surface methodology were employed. The optimum blending condition was determined using the rumen simulated in vitro fermentation. An additive formulated on the optimum condition contained 50% of protected fat, 25% of yeast culture, 5% of choline, 7% of organic zinc, 6.5% of cinnamon, and 6.5% of stevioside. The feed additive was supplemented at a rate of 0.1% of diet (orchard grass:concentrate, 3:7) and compared with a control which had no additive. The treatment resulted in lower volatile fatty acid (VFA) concentration and biogas than the control. To investigate the effect of the optimized additive and feed energy levels on rumen and rectal temperatures, four rumen cannulated Hanwoo (Korean native beef breed) steers were in a $4{\times}4$ Latin square design. Energy levels were varied to low and high by altering the ratio of forage to concentrate in diet: low energy (6:4) and high energy (4:6). The additive was added at a rate of 0.1% of the diet. The following parameters were measured; feed intake, rumen and rectal temperatures, ruminal pH and VFA concentration. This study was conducted in an environmentally controlled house with temperature set at $30^{\circ}C$ and relative humidity levels of 70%. Steers were housed individually in raised crates to facilitate collection of urine and feces. The adaptation period was for 14 days, 2 days for sampling and 7 days for resting the animals. The additive significantly reduced both rumen (p<0.01) and rectal temperatures (p<0.001) without depressed feed intake. There were interactions (p<0.01) between energy level and additive on ruminal temperature. Neither additive nor energy level had an effect on total VFA concentration. The additive however, significantly increased (p<0.01) propionate and subsequently had lower acetate:propionate (A/P) ratios than non-additive supplementation. High concentrate diets had significantly lower pH. Interactions between energy and additive were observed (p<0.01) in ammonia nitrogen production. Supplementation of diets with the additive resulted in lower rumen and rectal temperatures, hence the additive showed promise in alleviating undesirable effects of heat stress in cattle.

• 한국환경농학회지
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• 제30권1호
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• pp.31-36
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• 2011

축산농가에서 발생되는 돈분 슬러리의 처리 능력을 평가하기 위하여 Full-scale의 단상 혐기성 소화조에서 중온소화와 고형물 체류시간을 20일로 하여 연속식으로 운전하면서 성능평가 및 특성연구를 실시하였다. 운전기간 중 알칼리도는 약 4,000 mg/L(3,500~9,000 mg/L as $CaCO_3$)이였고, 소화조내의 pH는 7.5~8.0 범위로 약간 높은 경향이었으나 pH는 안정적이었다. 바이오가스의 발생량은 OLR 1.2 $g{\cdot}COD/L{\cdot}day$에서 0.69 L/L/day의 바이오가스를 생산하였고, 제거된 COD를 바탕으로 계산된 메탄가스 발생량은 63% 수준이였다. 생산된 바이오가스 중 메탄가스 함량은 65~70%이었고, CO2는 약 30% 전후였으며, 열병합 발전을 실시하였을 때 총전력요구량의 50~75% 수준을 공급하였다. 또한 발전기 부하가 5~9 kW시 평균 1 kWh의 전력을 생산하기 위한 바이오가스 소모량은 약 1.8 $m^3$이였다. 따라서 실제 규모의 plant에서 약 500일간 운전한 결과 유입되는 돈분 슬러리의 TS 농도에 상관없이 소화조 내에 일정 농도의 유기물을 확보할 수 있었고, 바이오가스의 발생량은 일반적인 축산분뇨 가스 발생량 보다 높게 나타나 단상 혐기성 소화공정으로 고효율 처리가 가능한 것으로 나타났다.

• 대한환경공학회지
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• 제31권12호
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• pp.1113-1122
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• 2009

하수슬러지의 해양투기 배출규제에 대한 대체 처리방안으로, 하수슬러지의 초음파 가용화를 통한 재기질화와 하수처리 공정에 대한 개선을 통한 슬러지 발생량의 저감방안을 살펴보았다. 분리막 반응조(MBR) 실험을 통해 SRT를 점진적으로 SRT=5.1일에서 442일까지 증가시켰으며, 이때 반응조내 미생물의 평균 농도값은 $c_B$=3.4 $gTSSL^{-1}$에서 $c_B$=14.5 $gTSSL^{-1}$까지 증가하였다. 이때 기질제거율과 미생물의 성장량과의 관계를 나타내는 미생물 수율($Y_{B/S}$)는 SRT=5.1일 일때의 약 0.5-0.7에 비해 SRT=442일 일때 0.005-0.007로 저감되어, 직접적인 슬러지 발생량의 감소를 가져오게 되는 것을 확인하였다. 반응 조내 미생물 농도와 폭기효율과의 관계를 프로펠러 루프 반응조에서 교반속도에 따른 산소전달계수와 ${\alpha}$-factor의 변화로써 살펴보았다. 한편 슬러지에 대한 초음파 가용화는 에너지 투입량에 따라 가용화 효율이 증가하고, 가용화한 슬러지의 혐기성 소화효율은 가용화하지 않은 슬러지에 비해 바이오가스 발생량이 많았다.

• 대한환경공학회지
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• 제38권11호
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• pp.618-626
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• 2016

상온조건($25^{\circ}C$)에서 하수슬러지처리를 위한 생물전기화학 혐기성소화조의 성능에 미치는 제2철 이온($Fe^{+3}$)의 영향을 연구하였다. 생물전기화학 혐기성소화조를 상온에서 운전하였을 때 pH, 알카리도, COD 및 VFAs 등의 상태변수들은 안정하였으며, VS 제거율과 비메탄발생율은 각각 65.9% 및 370 mL/L/d이었다. 생물전기화학 혐기성소화조에 제2철 이온(200 ppm)을 주입한 후 상태변수들의 안정도는 더욱 향상되었으며, VS 제거율 및 비메탄발생량은 각각 69.8%, 396 mL/L/d로 증가하였다. 그러나, 제2철 이온을 주입 이후에 바이오가스의 메탄함량은 76.6%로 주입 이전의 77.3%에서 비하여 약간 감소하였다. 부유슬러지의 미생물 군집을 변화를 분석한 결과 공생 혐기성미생물(Cloacamonas) 및 가수분해균(Saprospiraceae, Ottowia pentelensis) 등의 우점균의 비율이 제2철 이온의 주입으로 증가하였다. 이것은 철이온의 주입으로 부유혐기성미생물(planktonic anaerobic bacteria, PAB)의 활성이 증가하였음을 나타낸다. 제2철 이온은 상온조건에서 하수슬러지처리를 위한생물전기화학 혐기성소화조의 성능을 향상시킨다.

• 한국환경보건학회지
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• 제21권4호
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• pp.1-9
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• 1995

This study was carried to investigate the biodegradability of phenol in the wastewater with the two sludge blanket-packed bed reactor in series. Each reactor had a dimension of 0.09 m i.d. and 1.5 m height and consisted of two regions. The lower region was a sludge blanket of 0.5 m height and the upper region was a packed-bed of 1 m height. The packed bed region was charged with ceramic raschig rings of 10 mm i.d., 15 mm o.d. and 20 mm length. The reactors were operated at 35$\circ$C and the hydraulic retention time(HRT) was maintained 24 hours. The synthetic wastewater composed of glucose and phenol as major components was fed into the reactor in a continuous mode with incereasing phenol concentration. In addition, the nutrient trace metals($Na^+, Mg^{2+}, Ca^{2+}, PO_4^{3-}, NH_4^+, Co^{2+}, Fe^{2+}$ etc.) were added for growing anaerobes. The phenol concentration of the effluent, the overall gas production, the composition of product gas, the efficiency of COD reduction and the duration of acclimation period were measured to determine the performance of the anaerobic wastewater treatment system as the phenol concentration of the influent was increased from 600 to 2400 mg//l. Successfully stable biodegradation of phenol could be achieved with the anaerobic treatment system from 600 to 1, 800 mg/l of the influent phenol concentration. The upper level of influent phenol loading was high enough to meet most of the practical requirement. The duration of acclimation increased with the phenol loading. At steady state of the influent phenol concentration of 1800 mg/l, the treatment performance indicated the phenol reduction efficiency of 99%, the COD reduction efficiency of 99% and the gas production rate of 37 l/day. At the influent phenol concentration of 2400 mg/l, however, the operation of the treatment system was noted unstable. While the concentration of methane in biogas decreased with increasing the influent phenol loading, the carbon dioxide was increased. However, the concentration of hydrogen was varied negligibly. The concentration of methane was high enough to be used as a fuel. As a result, it is suggested that anaerobic phenol wastewater treament was economical in the sense of energy recovery and wastewater treatment.