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Yun, Yeo-Myeong,Sung, Shihwu,Kang, Seoktae,Kim, Mi-Sun,Kim, Dong-Hoon Elsevier 2017 ENERGY Vol.135 No.-
<P><B>Abstract</B></P> <P>Biomethanation by hydrogenotrophic methanogens has been proven as a potential process for managing renewable power intermittency and upgrading biogas. The present work aimed to enrich hydrogenotrophic methanogens under different mixing conditions (gas recycle <I>vs.</I> mechanical mixing) and temperatures (mesophilic <I>vs.</I> thermophilic conditions) for biogas upgrading. The synthetic gas (H<SUB>2</SUB>:CO<SUB>2</SUB> = 4:1) was fed to the reactor bottom at a hydrogen injection rate (HIR) of 1.6 L H<SUB>2</SUB> L<SUP>−1</SUP> d<SUP>−1</SUP>. The gas recycle (100 L L<SUP>−1</SUP> d<SUP>−1</SUP>) under thermophilic condition was found to be the most effective, reaching over 96% H<SUB>2</SUB> conversion to CH<SUB>4</SUB> within 15 d of operation. Archaea community analysis performed by 454 pyrosequencing showed that the sequence of <I>Methanosaeta</I> sp. decreased while obligate-hydrogenotrophic methanogens increased: <I>Methanoculleus chikugoensis</I> (19.5%) and <I>Methanothermococcus thermolithotrophicus</I> (28.1%) under mesophilic and thermophilic condition, respectively. To the thermophilic enriched culture, the biogas produced from an up-flow anaerobic sludge blanket reactor with additional hydrogen (four times of CO<SUB>2</SUB>) was fed at various HIRs for 200 d. As HIR increased, H<SUB>2</SUB> consumption rate also increased with CO<SUB>2</SUB> removal contained in the biogas. Up to an HIR increase to 19.2 L H<SUB>2</SUB> L<SUP>−1</SUP> d<SUP>−1</SUP>, the high calorific biomethane (96% of CH<SUB>4</SUB>) could be obtained at gas recycle rate of 200 L L<SUP>−1</SUP> d<SUP>−1</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biomethanation by hydrogenotrophs for upgrading biogas by applying gas recycle. </LI> <LI> Highest performance achieved by applying gas recycle under thermophilic condition. </LI> <LI> A gradual increase in obligate-hydrogenotrophic methanogens after enrichment. </LI> <LI> Almost complete conversion of H<SUB>2</SUB> to CH<SUB>4</SUB> at 19.2 L H<SUB>2</SUB> L<SUP>−1</SUP> d<SUP>−1</SUP>. </LI> <LI> Achievement of high calorific biomethane (96% CH<SUB>4</SUB>) during long term operation. </LI> </UL> </P>
Biohydrogen production from food waste: Current status, limitations, and future perspectives
Yun, Yeo-Myeong,Lee, Mo-Kwon,Im, Seong-Won,Marone, Antonella,Trably, Eric,Shin, Sang-Ryong,Kim, Min-Gyun,Cho, Si-Kyung,Kim, Dong-Hoon Elsevier Applied Science 2018 Bioresource technology Vol.248 No.1
<P><B>Abstract</B></P> <P>Among the various biological routes for H<SUB>2</SUB> production, dark fermentation is considered the most practically applicable owing to its capability to degrade organic wastes and high H<SUB>2</SUB> production rate. Food waste (FW) has high carbohydrate content and easily hydrolysable in nature, exhibiting higher H<SUB>2</SUB> production potential than that of other organic wastes. In this review article, first, the current status of H<SUB>2</SUB> production from FW by dark fermentation and the strategies applied for enhanced performance are briefly summarized. Then, the technical and economic limitations of dark fermentation of FW are thoroughly discussed. Economic assessment revealed that the economic feasibility of H<SUB>2</SUB> production from FW by dark fermentation is questionable. Current efforts to further increase H<SUB>2</SUB> yield and waste removal efficiency are also introduced. Finally, future perspectives along with possible routes converting dark fermentation effluent to valuable fuels and chemicals are discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Critical reviews on dark fermentation of food waste (FW). </LI> <LI> Current status of dark fermentation with strategies applied for enhancement. </LI> <LI> Technical and economical limitation of dark fermentation performance of FW. </LI> <LI> Strategies to increase H<SUB>2</SUB> yield and gain more energy. </LI> <LI> Integrated system converting fermentation effluent to various fuels and chemicals. </LI> </UL> </P>
Yun, Yeo-Myeong,Kim, Myungchan,Kim, Hyojeon,Kim, Dong-Hoon,Kwon, Eilhann E.,Kang, Seoktae Elsevier 2019 Journal of environmental management Vol.234 No.-
<P><B>Abstract</B></P> <P>Demineralization is required in upgrading low-grade coal to serve as an alternative energy resource for the production of fuel and valuable chemicals but generates a large amount of low-grade coal wastewater (LCWW). The objective of this study was to investigate the effects of a co-substrate on an anaerobic membrane bioreactor (AnMBR) treating LCWW. CH<SUB>4</SUB> was not produced during the operation fed by LCWW alone. When yeast wastes (YW) were supplemented, there was a gradual increase in the biodegradability of LCWW, achieving 182 CH<SUB>4</SUB> mL/g COD with 58% COD removal efficiency. The analysis of physicochemical characteristics in the effluent of AnMBR, done by excitation-emission matrix (EEM) and size exclusion chromatography (SEC), showed that the proportion of soluble microbial products (SMPs) and aromatic group with high-molecular weight (>1 kDa) increased. Microbial analysis revealed that the increased dominance of bacteria <I>Comamonas</I>, <I>Methanococcus,</I> and <I>Methanosarcina</I> facilitated biodegradation of LCWW in the presence of YW.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Enhanced biodegradation of low-grade coal wastewater by adding yeast extract. </LI> <LI> Increased soluble microbial products and aromatic groups with high molecular weight. </LI> <LI> Increased dominance of bacteria <I>Comamonas</I>, <I>Methanococcus,</I> and <I>Methanosarcina</I>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Yun, Yeo-Myeong,Shin, Hang-Sik,Lee, Chang-Kyu,Oh, You-Kwan,Kim, Hyun-Woo Springer-Verlag 2016 Environmental Science and Pollution Research Vol.23 No.8
<P>Converting lipid-extracted microalgal wastes to methane (CH4) via anaerobic digestion (AD) has the potential to make microalgae-based biodiesel platform more sustainable. However, it is apparent that remaining n-hexane (C6H14) from lipid extraction could inhibit metabolic pathway of methanogens. To test an inhibitory influence of residual n-hexane, this study conducted a series of batch AD by mixing lipid-extracted Chlorella vulgaris with a wide range of n-hexane concentration (similar to 10 g chemical oxygen demand (COD)/L). Experimental results show that the inhibition of n-hexane on CH4 yield was negligible up to 2 g COD/L and inhibition to methanogenesis became significant when it was higher than 4 g COD/L based on quantitative mass balance. Inhibition threshold was about 4 g COD/L of n-hexane. Analytical result of microbial community profile revealed that dominance of alkane-degrading sulfate-reducing bacteria (SRB) and syntrophic bacteria increased, while that of methanogens sharply dropped as n-hexane concentration increased. These findings offer a useful guideline of threshold n-hexane concentration and microbial community shift for the AD of lipid-extracted microalgal wastes.</P>
( Yeo Myeong Yun ),( Dong Hoon Kim ),( Hang Sik Shin ) 한국폐기물자원순환학회(구 한국폐기물학회) 2013 한국폐기물자원순환학회 추계학술발표논문집 Vol.2013 No.-
Waste activated sludge (WAS) and food waste (FW) are available year round at low cost and have the potential to promote synergism in anaerobic digestion (AD). The goal of this study was to clarify the synergism in co-digestion of WAS and FW. A slight amount of FW at various ratios was added to WAS as an auxiliary substrate, and anaerobic batch tests were performed under mesophilic conditions. By adding FW, total CH4 produced was increased, where most of them were come from WAS, clearly suggesting synergism. Also, lag period was shortened and CH4 production rate was increased by FW addition. It was hypothesized that enhanced performance was owing to the facilitated hydrolysis of WAS by FW addition, which was revealed by the increased activities of hydrolytic -amylase and protease.
Yun, Yeo-Myeong,Lee, Eunjin,Kim, Kwiyong,Han, Jong-In Elsevier 2019 CHEMOSPHERE - Vol.233 No.-
<P><B>Abstract</B></P> <P>This study aimed to design a sulfate-reducing bacteria (SRB)-based wastewater treatment system (SWTS) integrated with a sulfide fuel cell (SFC) as an alternative to the energy-intensive aerobic wastewater treatment process. The result showed that the COD/sulfate ratio and hydraulic retention time (HRT) were two important parameters in a SWTS. The highest COD and sulfate removal efficiency rates were at a HRT of 4 h at a COD/sulfate ratio of 0.67, reaching 83 ± 0.2% and 84 ± 0.4% with sulfate removal rates of 4.087 ± 32 mg SO<SUB>4</SUB> <SUP>2−</SUP>/d, respectively. A microbial analysis revealed that the dominance of nine OTUs belonging to SRB closely affected the high sulfate removal efficiency in the SWTS. At the HRT of 8 h, voltage of 0.02 V and a power density level of 130 mW/m<SUP>2</SUP> were obtained with sulfide removal efficiency of 99 ± 0.5%. These results overall demonstrate that SRB can serve as a green and effective route for wastewater treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SWTS integrated with SFC for simultaneous WW treatment and electricity production. </LI> <LI> Achievement of COD and sulfate removal efficiency of 83% and 84% in the SWTS. </LI> <LI> Highest COD and sulfate removal efficiency at 4 h HRT at 0.67 COD/sulfate ratio. </LI> <LI> The SFC generating 0.02 V and 130 mW/m<SUP>2</SUP> with 99% of sulfide removal efficiency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Yeo-Myeong Yun,Hang-Sik Shin,Dong-Hoon Kim 한국폐기물자원순환학회 2013 한국폐기물자원순환학회 학술대회 Vol.2013 No.2
Waste activated sludge (WAS) and food waste (FW) are available year round at low cost and have the potential to promote synergism in anaerobic digestion (AD). The goal of this study was to clarify the synergism in co-digestion of WAS and FW. A slight amount of FW at various ratios was added to WAS as an auxiliary substrate, and anaerobic batch tests were performed under mesophilic conditions. By adding FW, total CH₄ produced was increased, where most of them were come from WAS, clearly suggesting synergism. Also, lag period was shortened and CH₄ production rate was increased by FW addition. It was hypothesized that enhanced performance was owing to the facilitated hydrolysis of WAS by FW addition, which was revealed by the increased activities of hydrolytic α-amylase and protease.