• Environmental Engineering Research
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• 제24권1호
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• pp.38-44
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• 2019

The Biochemical Methane Potential (BMP) of fresh leachate and domestic wastewaters codigestion was determined by laboratory Bach Tests at $35^{\circ}C$ over a period of 90 d using a wide range of leachates volumetric ratios from 0% to 100%. To simulate wastewaters plant treatment step, all the ratios were first air stripped for 48 h before anaerobic incubation. The kinetic of biogas production was assessed using modified Gompertz model and exponential equation. The results obtained showed that cumulative biogas production was insignificant in the case of wastewaters monodigestion while the codigestion significantly improves the BMP. Air stripping pretreatment had positive effect on both ammonium concentration and volatiles fatty acids with reduction up to 75% and 42%, respectively. According to the Modified Gompertz model, the optimal anaerobic co-digestion conditions both in terms of maximal biogas potential, start-up period and maximum daily biogas production rate, could be achieved within large leachate volumetric ratios from 25% to 75% with a maximum BMP value of 438.42 mL/g volatile solid at 50% leachate ratio. The positive effect of codigestion was attributed to a dilution effect of chemical oxygen demand and volatile fatty acid concentrations to optimal range that was between 11.7 to $32.3gO_2/L$ and 2.1 to 7.4 g/L, respectively. These results suggested that the treatment of fresh leachate by their dilution and co digestion at wastewaters treatment plants could be a promising alternative for both energetic and treatment purposes.

• 한국물환경학회지
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• 제35권4호
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• pp.299-307
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• 2019

The purpose of this study was to investigate the effect of low temperature thermal pre-treatment on biodegradation of waste activated sludge for anaerobic digestion as a countermeasure for increasing sludge generation. The experimental condition was accomplished in 2 %, 4 %, and 6 % TS concentration, and $70^{\circ}C$, $80^{\circ}C$, $90^{\circ}C$ of temperature for a maximum of 120 minutes retention time. Then, it was followed by analysis of physical/chemical properties, BMP test and composition of biogas. The biogas characteristic was evaluated by applying the modified Gomperz model. As a result, solubility of dissolved substrate, such as $SCOD_{Cr}$, soluble carbohydrate, and soluble protein, and biogas production increased as temperature increased. Solubilization efficiency at $90^{\circ}C$ was 18.4 %, 17.03 % and 16.88% in 2 %, 4 %, and 6 % TS concentration respectively. Also, solubilization rates of carbohydrate and protein similarly increased. BMP test results also showed that methane production in excess sludge increased to 0.194, 0.187 and $0.182m^3/kg$ VS. respectively, and lag phase decreased to 0.145, 0.220, 0.351 day due to acceleration of the hydrolysis step. Consequently, low-temperature thermal pre-treatment could increase biodegradability of sludge, positively affecting biogas production and sludge reduction.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.57-67
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• 2022

The curing characteristics of naphthalene type epoxy resin systems according to the change of curing agent were investigated to develop a new next-generation EMC(Epoxy Molding Compound) with excellent warpage characteristics, low thermal expansion, and excellent fluidity for WLP(Wafer Level Package). As epoxy resins, DGEBA, which are representative bisphenol type epoxy resins, NE-16, which are the base resins of naphthalene type epoxy resins, and NET-OH, NET-MA, and NET-Epoxy resins newly synthesized based on NE-16 were used. As a curing agent, DDM (Diamino Diphenyl Methane) and CBN resin with naphthalene moiety were used. The curing reaction characteristics of these epoxy resin systems with curing agents were analyzed through thermal analysis experiments. In terms of curing reaction mechanism, DGEBA and NET-OH resin systems follow the nth curing reaction mechanism, and NE-16, NET-MA and NET-Epoxy resin systems follow the autocatalytic curing reaction mechanism in the case of epoxy resin systems using DDM as curing agent. On the other hand, it was found that all of them showed the nth curing reaction mechanism in the case of epoxy resin systems using CBN as the curing agent. Comparing the curing reaction rate, the epoxy resin systems using CBN as the curing agent showed a faster curing reaction rate than them with DDM as a hardener in the case of DGEBA and NET-OH epoxy resin systems following the same nth curing reaction mechanism, and the epoxy resin systems with a different curing mechanism using CBN as a curing agent showed a faster curing reaction rate than DDM hardener systems except for the NE-16 epoxy resin system. These reasons were comparatively explained using the reaction rate parameters obtained through thermal analysis experiments. Based on these results, low thermal expansion, warpage reduction, and curing reaction rate in the epoxy resin systems can be improved by using CBN curing agent with a naphthalene moiety.

• Animal Bioscience
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• 제37권3호
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• pp.405-418
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• 2024

In recent years, there has been a growing argument attributing the primary cause of global climate change to livestock industry, which has led to the perception that the livestock industry is synonymous with greenhouse gas (GHG) emissions. However, a closer examination of the global GHG emission by sector reveals that the energy sector is responsible for the majority, accounting for 76.2% of the total, while agriculture contributes 11.9%. According to data from the Food and Agriculture Organization of the United Nations (FAO), the total GHG emissions associate with the livestock supply chain amount to 14.5%. Within this, emissions from direct sources, such as enteric fermentation and livestock manure treatment, which are not part of the front and rear industries, represent only 7%. Although it is true that the increase in meat consumption driven by global population growth and rising incomes, has contributed to higher methane (CH₄) emissions resulting from enteric fermentation in ruminant animals, categorizing the livestock industry as the primary source of GHG emissions oversimplifies a complex issue and disregards objective data. Therefore, it may be a misleading to solely focus on the livestock sector without addressing the significant emissions from the energy sector, which is the largest contributor to GHG emissions. The top priority should be the objective and accurate measurement of GHG emissions, followed by the development and implementation of suitable reduction policies for each industrial sector with significant GHG emissions contributions.

• 대한환경공학회지
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• 제28권1호
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• pp.61-66
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• 2006

슬러리 형태의 돈사폐수로부터 자원회수와 질소제거를 위하여 순차적으로 ADEPT(Anaerobic digestion elutriated phased treatment) 공정과 SHARON(Single reactor system High Ammonium Removal Over nitrite)-ANAMMOX(Anaerobic ammonium oxidation)공정을 결합하여 운전하였다. ADEPT 공정은 부하율 3.95 gSCOD/L-day에서 운전되었고, SCOD 생성율과 산생성율은 각각 5.3 gSCOD/L-day와 3.3 gVFAs/L-day(as COD)였다. 가수분해에 의한 VS감소와 SCOD생성율은 각각 13%와 0.19 $gSCOD_{prod}/gVS_{feeding}$였으며, 산생성율은 0.80 $gVFAs/gSCOD_{prod.}$였다. 메탄발효조에서 가스생성율과 메탄함량은 각각 2.8 L/day($0.3m^3CH_4/kgCOD_{removal}\;@STP$) 및 77%였다. 운전조건에서 $NH_4-N$ 94.1% (TKN으로서 86.5%) 및 T-P 87.3%가 제거되었다.

• Journal of Animal Science and Technology
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• 제60권11호
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• pp.27.1-27.8
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• 2018

Background: Enteric methane ($CH_4$) accounts for about 70% of total $CH_4$ emissions from the ruminant animals. Researchers are exploring ways to mitigate enteric $CH_4$ emissions from ruminants. Recently, nano zinc oxide (nZnO) has shown potential in reducing $CH_4$ and hydrogen sulfide ($H_2S$) production from the liquid manure under anaerobic storage conditions. Four different levels of nZnO and two types of feed were mixed with rumen fluid to investigate the efficacy of nZnO in mitigating gaseous production. Methods: All experiments with four replicates were conducted in batches in 250 mL glass bottles paired with the ANKOM$^{RF}$ wireless gas production monitoring system. Gas production was monitored continuously for 72 h at a constant temperature of $39{\pm}1^{\circ}C$ in a water bath. Headspace gas samples were collected using gas-tight syringes from the Tedlar bags connected to the glass bottles and analyzed for greenhouse gases ($CH_4$ and carbon dioxide-$CO_2$) and $H_2S$ concentrations. $CH_4$ and $CO_2$ gas concentrations were analyzed using an SRI-8610 Gas Chromatograph and $H_2S$ concentrations were measured using a Jerome 631X meter. At the same time, substrate (i.e. mixed rumen fluid+ NP treatment+ feed composite) samples were collected from the glass bottles at the beginning and at the end of an experiment for bacterial counts, and volatile fatty acids (VFAs) analysis. Results: Compared to the control treatment the $H_2S$ and GHGs concentration reduction after 72 h of the tested nZnO levels varied between 4.89 to 53.65%. Additionally, 0.47 to 22.21% microbial population reduction was observed from the applied nZnO treatments. Application of nZnO at a rate of $1000{\mu}g\;g^{-1}$ have exhibited the highest amount of concentration reductions for all three gases and microbial population. Conclusion: Results suggest that both 500 and $1000{\mu}g\;g^{-1}$ nZnO application levels have the potential to reduce GHG and $H_2S$ concentrations.

• 한국미생물·생명공학회지
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• 제49권2호
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• pp.225-238
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• 2021

옥수수(Zea mays)와 톨페스큐(Festuca arundinacea) 근권 토양을 접종원으로 사용하여 농화배양을 통해 CH₄ 산화컨소시움과 N₂O 환원 컨소시움을 얻었다. Illumina MiSeq 염기서열 분석법으로 접종원과 컨소시움의 세균 군집 특성을 비교하였고, 컨소시움의 CH₄ 산화와 N₂O 환원 활성에 미치는 뿌리삼출물의 영향을 규명하였다. 접종원이 다름에도 불구하고 옥수수와 톨페스큐 유래 CH₄ 산화 컨소시움 사이의 유사성이 높았고, 2종의 N₂O 환원 컨소시움도 서로 유사성이 높았다. 2종의 CH₄ 산화 컨소시움에서 우점도가 높은 metanotrophs는 Methylosarcina, Methylococcus 및 Methylocystis이었다. 2 종의 N₂O 환원 컨소시움에서 대표적인 N₂O 환원 세균은 Cloacibacterium, Azonexus 및 Klebsiella이었다. 옥수수 근권 유래 N₂O 환원 컨소시움의 N₂O 환원 속도는 옥수수 뿌리삼출물 첨가에 의해 1.6배, 톨페스큐 유래 컨소시움의 N₂O 환원 속도는 톨페스큐 뿌리삼출물 첨가에 의해 2.7배 향상되었다. 그러나 CH₄ 산화 컨소시움의 활성은 뿌리삼출물 첨가에 의해 향상되지 않았다. 본 연구의 옥수수 및 톨페스큐 근권 유래 CH₄ 산화 및 N₂O 환원 컨소시움은 유류 오염 정화과정에서 non-CO₂ 온실가스배출을 저감하는데 활용 가능하다.

• 한국농림기상학회지
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• 제23권3호
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• pp.141-148
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• 2021

솔라 쉐어링이라고도 불리는 영농형 태양광은 작물의 광포화점 이상의 태양광을 솔라 패널을 이용한 발전에 활용하는 개념으로, 잉여 태양광 차단에 따른 지면에 입사하는 태양복사 에너지의 감소로 인한 증발산량 감소와 함께 지면 냉각 효과로 메탄 배출량도 줄이는 효과를 가져올 수 있어 기후 스마트 농업을 구현할 수 있는 기술로 기대되고 있다. 본 연구에서는 파주 영농형 태양광 시설 하부 및 외부 논에 상/하향 장/단파 복사, 기온, 습도, 지온, 수온, 풍향, 풍속 등을 관측하는 자동기상관측장비를 설치하여 시설 하부와 외부의 농업환경을 관측하고 비교함으로써, 영농형 태양광이 농가에 태양광 발전을 통한 부가적인 수입을 안기면서 재배 시 발생하는 물 소비와 메탄 배출을 줄이는 기후 스마트 농업 실현에 적합한지 그 가능성을 확인해 보았다. 관측 기간 동안 영농형 태양광 시설 하부의 평균 일사량은 노지 일사량의 약 70% 정도였으며, 영농형 태양광 시설 하부 논과 노지 논에서 기온의 차이는 거의 없었지만 지온과 수온은 명확한 차이가 확인되었다. 실제로 이러한 환경의 차이가 물 소비량 및 온실가스 배출량 감소로 이어지는지 플럭스 실측을 통한 확인이 요구된다.

• 적정기술학회지
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• 제7권1호
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• pp.59-71
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• 2021

하이브리드수열탄화 (Hybrid HTC) 기술은 2가지 이상의 유기성폐기물을 혼합한 특허 받은 열역학 공정으로 공정온도 180~250℃, 압력 20~40 bar에서 반응시간이 2시간 이내이며 에너지 소비가 적고, 폐기물의 부피감소 및 악취 저감효과가 크다. 폐기물 중 대부분의 탄소가 최종 생성물에 축적되므로 유기성 폐기물 고형연료화에 가장 적합한 기술로 평가받고 있다. 본 연구에서는 하이브리드 수열탄화기술을 활용하여 캄보디아 망고 폐기물을 대상으로 온도 및 반응시간의 변화에 따라 발열량 및 수율 등에 미치는 영향에 대하여 평가하였다. 본 연구를 통해 공정변수를 최적화하고, 전공정플랜트의 에너지 효율성을 향상시킬 수 있으며, 수연탄화기술에서 분해되어 가스가 생성되는데 이때 수소(H₂) 및 메탄(CH₄) 등 제조 및 생산기술개발을 할 수 있다. 본 연구 결과를 토대로 망고폐기물(2t/day)실증 물질수지 및 에너지 수지 도출과 함께 경제성도 평가하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.82-89
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• 2009

Two in vitro experiments were conducted to examine the effects of propionate precursors in the dicarboxylic acid pathway on ruminal fermentatation characteristics, $CH_4$ production and degradation of feed by rumen microbes. Fumarate or malate as sodium salts (Exp. 1) or acid type (Exp. 2) were added to the culture solution (150 ml, 50% strained rumen fluid and 50% artificial saliva) to achieve final concentrations of 0, 8, 16 and 24 mM, and incubated anaerobically for 0, 1, 3, 6, 9 and 12 h at $39^{\circ}C$. For both experiments, two grams of feed consisting of 70% concentrate and 30% ground alfalfa (DM basis) were prepared in a nylon bag, and were placed in a bottle containing the culture solution. Addition of fumarate or malate in both sodium salt and acid form increased (p<0.0001) pH of culture solution at 3, 6, 9 and 12 h incubations. The pH (p<0.0001) and total volatile fatty acids (VFA, p<0.05) were enhanced by these precursors as sodium salt at 3, 6 and 9 h incubations, and pH (p<0.001) and total VFA (p<0.01) from fumarate or malate in acid form were enhanced at a late stage of fermentation (9 h and 12 h) as the addition level increased. pH was higher (p<0.001) for fumarate than for malate as sodium salt at 3 h and 6 h incubations. Propionate ($C_3$) proportion was increased (p<0.0001) but those of $C_2$ (p<0.05) and $C_4$ (p<0.01 - p<0.001) were reduced by the addition of sodium salt precursors from 3 h to 12 incubation times while both precursors in acid form enhanced (p<0.011 - p<0.0001) proportion of $C_3$ from 6h but reduced (p<0.018 - p<0.0005) $C_4$ proportion at incubation times of 1, 3, 9 and 12 h. Proportion of $C_3$ was increased (p<0.05 - p<0.0001) at all incubation times by both precursors as sodium salt while that of $C_3$ was increased (p<0.001) from 6h but $C_4$ proportion was decreased by both precursors in acid form as the addition level increased. Proportion of $C_3$ was higher (p<0.01 - p<0.001) for fumarate than malate as sodium salt from 6 h incubation but was higher for malate than fumarate in acid form at 9 h (p<0.05) and 12 h (p<0.01) incubation times. Increased levels (16 and 24 mM) of fumarate or malate as sodium salt (p<0.017) and both precursors in acid form (p<0.028) increased the total gas production, but no differences were found between precursors in both chemical types. Propionate precursors in both chemical types clearly reduced (p<0.0001 - p<0.0002) $CH_4$ production, and the reduction (p<0.001 - p<0.0001) was dose dependent as the addition level of precursors increased. The $CH_4$ generated was smaller (p<0.01 - p<0.0001) for fumarate than for malate in both chemical types. Addition of fumarate or malate as sodium type reduced (p<0.004) dry matter degradation while both precursors in both chemical types slightly increased neutral detergent fiber degradability of feed in the nylon bag.