• Title, Summary, Keyword: Solid digestion

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Comparative Analysis of Performance and Microbial Characteristics Between High-Solid and Low-Solid Anaerobic Digestion of Sewage Sludge Under Mesophilic Conditions

  • Lu, Qin;Yi, Jing;Yang, Dianhai
    • Journal of Microbiology and Biotechnology
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    • v.26 no.1
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    • pp.110-119
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    • 2016
  • High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

A Study on Usage of Results from Batch Reactor for Design of Aerobic Digestion (호기성 소화조 설계시 회분식 반응조에서 획득된 결과의 이용방안에 관한 연구)

  • Choung, Youn-Kyoo;Ko, Kwang-Baik;Park, Joon-hong
    • Journal of Korean Society of Water and Wastewater
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    • v.8 no.3
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    • pp.1-8
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    • 1994
  • In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.

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Conversion of organic residue from solid-state anaerobic digestion of livestock waste to produce the solid fuel through hydrothermal carbonization

  • Yang, Seung Kyu;Kim, Daegi;Han, Seong Kuk;Kim, Ho;Park, Seyong
    • Environmental Engineering Research
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    • v.23 no.4
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    • pp.456-461
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    • 2018
  • The solid-state anaerobic digestion (SS-AD) has promoted the development and application for biogas production from biomass which operate a high solid content feedstock, as higher than 15% of total solids. However, the digested byproduct of SS-AD can be used as a fertilizer or as solid fuel, but it has serious problems: high moisture content and poor dewaterability. The organic residue from SS-AD has to be improved to address these problems and to make it a useful alternative energy source. Hydrothermal carbonization was investigated for conversion of the organic residue from the SS-AD of livestock waste to solid fuels. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures within the range of $180-240^{\circ}C$. Hydrothermal carbonization increased the calorific value through the reduction of the hydrogen and oxygen contents of the solid fuel, in addition to its drying performance. Therefore, after the hydrothermal carbonization, the H/C and O/C atomic ratios decreased through the chemical conversion. Thermogravimatric analysis provided the changed combustion characteristics due to the improvement of the fuel properties. As a result, the hydrothermal carbonization process can be said to be an advantageous technology in terms of improving the properties of organic waste as a solid-recovered fuel product.

Comparison of the Performance of Chamber and Bag Digesters for Solid State Anaerobic Digestion of Separated Solid Fraction of Swine Manure

  • Lee, Jaehee;Lee, Seunghun;Kim, Eunjong;Jo, Hyunsoo;Ahn, Heekwon
    • Korean Journal of Soil Science and Fertilizer
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    • v.48 no.2
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    • pp.94-99
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    • 2015
  • The performance of chamber and bag digesters for solid state anaerobic digestion (SS-AD) of separated solid fraction of swine manure was investigated using lab-scale digester (4,460 mL total volume and 1,800 mL of effective volume) operating at $37^{\circ}C$ for 63 days. The performance of two different digester types was evaluated in terms of the kinetic constants of methane production obtained from the Gompertz and Gaussian equations. Methane production potential of chamber and bag digester was 202 and $218N{\cdot}mL$ $CH_4/g$ VS. Time to produce 95% methane production potential (T95) and calculated effective anaerobic digestion time were 55.5 days and 41.8 days for chamber digester and 52.8 days and 43.5 days for bag digester, respectively. Our results reveal that the performance was not significantly different between chamber and bag digester.

Operational and Performance parameters of Anaerobic Digestion of Municipal Solid Waste (도시쓰레기 혐기성소화 운용 및 성능 지표)

  • Chung, Jae-Chun;Park, Chan-Hyuk;Son, Sung-Myung
    • Journal of the Korea Organic Resources Recycling Association
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    • v.10 no.4
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    • pp.86-95
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    • 2002
  • Anaerobic digestion of municipal solid waste(MSW) is recently getting attention due to energy generation and abatement of global warming. MSW has high solid content and low nitrogen content. Its major component is cellulose and hemicellulose. The conversion rate of organic portion of MSW to methane is approximately 50%, representing $0.2m^3/kg$ VS. Long hydraulic retention time is required for high solid content and inoculum should be mixed with the feed. When MSW is digested anaerobically, maximum limit of C/N ratio is 25 and the optimum concentration of $NH_3-N$ is 700mg/L. lime and sodium bicarbonate are used to adjust pH. Excess addition of sodium bicarbonate above 3,500mg/L will cause sodium toxicity. Thermophilic anaerobic digestion is effective in the control of pathogen although its operation and maintenance is difficult. To optimize the anaerobic digestion of MSW, it is necessary to understand the mechanism of microorganims involved in anaerobic digestion.

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Evaluation of Mixing Effects on Solid-state Anaerobic Digestion Performance of Dairy Manure and Sawdust Bedding Mixtures

  • Jo, Hyeonsoo;Lee, Seunghun;Lee, Jaehee;Kim, Eunjong;Ahn, Heekwon
    • Korean Journal of Soil Science and Fertilizer
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    • v.49 no.3
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    • pp.227-234
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    • 2016
  • The influence of mixing on biogas production and organic material removal performance of solid state anaerobic digestion of dairy manure and sawdust bedding mixtures was evaluated using 22 L volume lab-scale digesters. After 45 days of anaerobic digestion at $37^{\circ}C$, cumulative methane yield of unmixed test unit ($73.1N{\cdot}mL/g-VS$) was almost 1.3 times of that of mixed one ($56.3N{\cdot}mL/g-VS$). The biodegradable volatile solids removal rate of unmixed test unit was 67%, which was almost 28% greater than mixed one. Our results reveal that unmixed condition is better than mixed one in terms of biogas production and organic material reduction.

The Bioenergy Conversion Characteristics of Feedlot Manure Discharging from Beef Cattle Barn

  • Oh, Seung-Yong;Kim, Chang-Hyun;Yoon, Young-Man
    • Korean Journal of Soil Science and Fertilizer
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    • v.48 no.6
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    • pp.697-704
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    • 2015
  • This study was carried out to assess bioenergy conversion efficiency by biogas and solid fuel production in the cattle feedlot manure discharged from beef cattle barn. Feedlot manure was sampled from the cattle farmhouse located in Yong-in, Gyeonggi during the mid-fattening stage, periodically. The chemical characteristics, BMP (Biochemical methane potential) and HV (Heating values) of feedlot cattle manures were analyzed. Total solid contents of cattle feedlot manure were in the range of 29.98~44.28%, and volatile solid contents were in the range of 23.53~24.47%. In the anaerobic digestion of cattle feedlot manure, the methane production potential has increased from 0.141 to $0.187Nm^3kg^{-1}-VS_{added}$. The methane production of fresh cattle feedlot manure showed the range $0.141{\sim}0.187Nm^3kg^{-1}$-Manure (average $0.047Nm^3kg^{-1}$-Manure), the LHVs (lower heating values) of the produced methane were in the range of $316{\sim}560kcalkg^{-1}$-Manure (average $400kcalkg^{-1}$-Manure). In the direct combustion of fresh cattle feedlot manure, the LHVs were measured in the range of $747{\sim}1,271kcalkg^{-1}$-Manure (average $916kcalkg^{-1}$-Manure), and LHVs of solid fuel which have the water content of 20% were in the range of $2,694{\sim}2,876kcalkg^{-1}$-Manure (average $2,791kcalkg^{-1}$-Manure). Then, the drying energy of average $443kcalkg^{-1}$-Manure was consumed in the production of solid fuel which has a water content of 20%. Therefore, the direct combustion of cattle feedlot manure showed about 2.3 times higher LHV than the LHV of methane produced by anaerobic digestion. And LHV of solid fuel was about 6.0 times higher than the LHV of methane produced by anaerobic digestion. Then, the production of solid fuel presented more bioenergy conversion efficiency than the biogas production in the bioenergy use of cattle feedlot manure.

Microbial Community Dynamics in Batch High-Solid Anaerobic Digestion of Food Waste Under Mesophilic Conditions

  • Yi, Jing;Dong, Bin;Xue, Yonggang;Li, Ning;Gao, Peng;Zhao, Yuxin;Dai, Lingling;Dai, Xiaohu
    • Journal of Microbiology and Biotechnology
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    • v.24 no.2
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    • pp.270-279
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    • 2014
  • Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g $VS_{removal}$. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.

A Study of Biological Hydrolysis Efficiency for Methane Digestion with Municipal Solid Waste (메탄발효를 위한 도시쓰레기 초고온 가용화 방법의 효율성 검토)

  • Cheon, Ji-Hoon;Hiroshi, Tsuno
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.5
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    • pp.561-572
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    • 2010
  • The efficiency of biological hydrolysis at $80^{\circ}C$ on municipal solid waste mixed with anaerobic digestion sludge was investigated in 100L batch reactors. The hydrolysis effect was observed within a day, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, and the effect was observed during two days, When the reactor used for post-treatment reactor. For both configurations, methane production rate decreased, when hydrolysis was carried out more than a day. Gaseous ammonia in the hydrolysis reactors was successtully removed by the ammonia stripping system. Microbial diversity analysis on the hydrolysis reactors indicated dependency of microbial diversity on the configuration of the hydrolysis reactors. Carbohydrate and lactate degrading microbes dominated in the hydrolysis reactor, when the hydrolysis reactor used for a pre-treatment reactor for methanogenesis, while protein degrading microbes dominated in the post-treatment reactor.

A Study on Sample Preparation for the Analysis of Trace Elements in Foods of Animal Origin by Ultra High Pressure Microwave Digestion (초고압초음파분해법을 이용한 축산물내 미량금속 잔류분석을 위한 시료전처리 방법)

  • Lee, Myoung-heon;Lee, Hee-su;Son, Seong-wan;Jung, Gab-soo;Park, Jong-myung;Kim, Sang-keun
    • Korean Journal of Veterinary Research
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    • v.43 no.3
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    • pp.393-398
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    • 2003
  • Simple and rapid sample preparation method for trace elements in foods of animal origin using ultra high pressure microwave digestion system (UHP/MDS) and inductively coupled plasma atomic emission spectrometer (ICP/AES) were developed. 1. For the digestion of sample using UHP-MDS, 20% nitric acid (v/v) was the most suitable solvent for the determination of trace elements in foods of animal origin. 2. The optimal digestion conditions for UHP-MDS were as follows: final temperature $180^{\circ}C$, final pressure 400 PSI, and magnetic power 900 W in the solid sample. For the liquid sample final temperature $170^{\circ}C$, final pressure 300 PSI and magnetic power 700 W were optimal conditions. 3. As result of interlaboratory test, the average recovery rate of the for solid sample were 88.3~99.1% for As, 82.4~93.3% for Cd, 89.2~101.2% for Hg and 86.5~93.8% for Pb, respectively. In liquid sample, it were 87.0~96.8% for As, 80.9~96.6% for Cd, 87.5~91.2% for Hg and 91.4~95.5% for Pb, respectively. 4. The average coefficient variation rate were 3.3~15.9% for solid sample and 2.9~10.8% for liquid sample.