Microbial communities change in an anaerobic digestion after application of microbial electrolysis cells

Lee, Beom,Park, Jun-Gyu,Shin, Won-Beom,Tian, Dong-Jie,Jun, Hang-Bae Elsevier 2017 Bioresource technology Vol.234 No.-

<P><B>Abstract</B></P> <P>Microbial electrolysis cells (MECs) are being studied to improve the efficiency of anaerobic digesters and biogas production. In the present study, we investigated the effects of electrochemical reactions in AD-MEC (anaerobic digester combined with MECs) on changes in the microbial communities of bulk sludge through 454-pyrosequencing analysis, as well as the effect of these changes on anaerobic digestion. <I>Methanobacterium beijingense</I> and <I>Methanobacterium petrolearium</I> were the dominant archaeal species in AD, while <I>Methanosarcina thermophila</I> and <I>Methanobacterium formicicum</I> were dominant in AD-MEC at steady-state. There were no substantial differences in dominant bacterial species. <I>Clostridia</I> class was more abundant than <I>Bacteroidia</I> class in both reactors. Compared to AD, AD-MEC showed a 40% increase in overall bacterial population, increasing the removal of organic matters and the conversion of volatile fatty acids (VFAs). Thus, the MEC reaction more effectively converts organic matters to VFAs and activates microbial communities favorable for methane production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Improving the generation of renewable sources of energy. </LI> <LI> Anaerobic digester and anaerobic digester combined with microbial electrolysis cells. </LI> <LI> Archaeal communities between the AD and AD-MEC. </LI> <LI> Increased methane production using activated microbial communities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Changes in the structure of microbial communities were observed in the bulk sludge of conventional anaerobic digester and anaerobic digester combined with microbial electrolysis cells (MECs). According to the results, there was a difference in the dominant species of the two reactors, where anaerobic digester combined with a MECs activates microbial communities associated with acetoclastic methanogens, thereby resulting in increased methane production.</P> <P>[DISPLAY OMISSION]</P>

기질 농도에 따른 미생물전기분해전지의 운전 특성

서휘진,김재일,기서진,안용태 유기성자원학회 2023 유기물자원화 Vol.31 No.4

본 연구는 주입 기질 농도에 따른 미생물전기분해전지 (Microbial electrolysis cell, MEC)의 운전성능을 조사하였다. 주입 기질 농도에 따른 MEC의 운전 성능을 비교하기 위해 6 개의 실험실 규모 MEC를 2, 4, 6 g/L Sodium acetate 조건으로 순서대로 주입 농도를 증가시켜 운전하였다. 전류밀도, 수소 생산량, SCOD 제거율을 분석하였고, 에너지 효율, cathodic hydrogen recovery를 계산하여 주입 기질 농도 별 MEC의 운전성능을 비교하였다. 체적 전류밀도는 4 g/L 조건에서 76.3 A/m3였고, 6 g/L로 주입 농도를 증가시켰을 때 19.0 A/m3로 4 g/L 주입 조건에 비해 75% 감소하였다. 수소 생산량은 4 g/L 주입 조건이 47.3 ± 16.8 mL로 가장 높았으나 수소 수율은 2 g/L 주입 조건이1.1 L H2/g CODin로 가장 높았다. 에너지 효율 역시 2 g/L 조건에서 가장 높았고, 6 g/L 조건에서 가장 낮은 결과를보여주었다. 최대 전기에너지 효율은 76.4%였으며, 2 g/L 조건에서 최대 전체에너지 효율은 39.7%였다. 그러나기질 농도가 6 g/L로 증가하였을 때, 성능이 급격히 감소하였다. Cathodic hydrogen recovery 역시 에너지 효율과유사한 경향을 보였으며, 가장 낮은 농도 조건에서 가장 높은 성능을 보여주었다. 따라서 MEC 운전에 있어서SCOD 제거율뿐만 아니라 에너지 효율 등을 고려한 최적 운전을 위해서는 낮은 주입 농도 조건에서 운전하는것이 바람직할 것으로 판단된다. This study examined the effect of input substrate concentration on hydrogen production of microbial electrolysis cells. To compare the performance of MEC according to the input substrate concentration, six laboratory-scale MEC reactors were operated by sequentially increasing the input substrate concentration from 2 g/L of sodium acetate, to 4 g/L, and 6 g/L. The current density, hydrogen production, and SCOD removal rate were analyzed, and energy efficiency and cathodic hydrogen recovery were calculated to compare the performance of MEC. The maximum volumetric current density was obtained at 4 g/L condition (76.3 A/m3) and it decreased to 19.0 A/m3, when the input concentration was increased to 6 g/L, which was a 75% decrease compared to the 4 g/L input condition. Maximum hydrogen production was obtained also at 4 g/L condition (47.3 ± 16.8 mL), but maximum hydrogen yield was obtained at 2 g/L input condition (1.1 L H2/g CODin). Energy efficiencies were also highest in 2 g/L condition; the lowest result was observed at 6 g/L condition. Maximum electrical energy efficiency was 76.4%, and the maximum overall energy efficiency was 39.7% at 2 g/L condition. However, when the substrate concentration increased to 6 g/L, the performance was drastically decreased. Cathodic hydrogen recovery also showed a similar tendency with energy efficiency, with the lowest concentration condition showing the best performance. It can be concluded that operating at low input substrate concentration might be better when considering not only hydrogen yield but also energy efficiency.

Green Hydrogen Production from Waste Feedstock Using Microbial Electrolysis Cells: Perspectives and State of the Art

Kyoung-Yeol Kim 한국신재생에너지학회 2021 AFORE Vol.2021 No.10

Principle of Electromethanogenesis in Microbial Electrolysis Cells: Materials, Configurations and Operations

Geonwoong JO,Sokhee JUNG 한국생물공학회 2023 한국생물공학회 학술대회 Vol.2023 No.4

Biohyrogen evolution in Microbial Electrolysis Cell: Present state of art

Sokhee P. Jung 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Microbial Electrolysis Cells: the Review of Advancements in the Cathodic Catalyst for the Hydrogen Evolution Reaction

Mohammad Mahasin Ali,Sokhee Jung(정석희) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11

Enhanced power generation from a microbial electrolysis cell-reverse electrodialysis hybrid system

Eunjin JWA,Hanki KIM,Namjo JEONG,Joo-Youn NAM 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Enhancing hydrogen production efficiency in microbial electrolysis cell with membrane electrode assembly cathode

Jia, Yu Hong,Ryu, Jae Hun,Kim, Cho Hui,Lee, Woo Kyung,Tran, Thi Van Trinh,Lee, Hyo Lee,Zhang, Rui Hong,Ahn, Dae Hee Elsevier 2012 Journal of industrial and engineering chemistry Vol.18 No.2

<P><B>Abstract</B></P><P>Microbial electrolysis cell is a device which can produce hydrogen gas from biomass through microbial catalyzed process and thus reduce the organic matter. For the real application in wastewater treatment, the scale-up of microbial electrolysis cell is an important issue but few tests were conducted with relatively large size. In this study, a 3.7L microbial electrolysis cell (liquid volume 3.2L) equipped with a membrane electrode assembly cathode was designed and tested. The internal resistance was examined, hydrogen generation and organic removal performance was investigated under different conditions. A maximum overall hydrogen efficiency of 41% was achieved at an applied voltage of 1.2V with acetate as substrate, corresponding to a volumetric hydrogen production rate of approximately 0.12m<SUP>3</SUP> H<SUB>2</SUB>/m<SUP>3</SUP> reactor liquid volume/day. The results obtained in this study could help to further develop pilot-MEC for practical applications.</P>

Microbial electrolysis cells for electromethanogenesis: Materials, configurations and operations

Aditya Amrut Pawar,Anandakrishnan Karthic,Sangmin Lee,Soumya Pandit,Sokhee P. Jung 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

Anaerobic digestion is a traditional method of producing methane-containing biogas by utilizing the methanogenic conversion of organic matter like agricultural waste and animal excreta. Recently, the application of microbial electrolysis cell (MECs) technology to a traditional anaerobic digestion system has been extensively studied to find new opportunities in increasing wastewater treatability and methane yield and producing valuable chemicals. The finding that both anodic and cathodic bacteria can synthesize methane has led to the efforts of optimizing multiple aspects like microbial species, formation of biofilms, substrate sources and electrode surface for higher production of the combustible compound. MECs are very fascinating because of its ability to uptake a wide variety of raw materials including untreated wastewater (and its microbial content as biocatalysts). Extensive work in this field has established different systems of MECs for hydrogen production and biodegradation of organic compounds. This review is dedicated to explaining the operating principles and mechanism of the MECs for electromethanogenesis using different biochemical pathways. Emphasis on single- and double-chambered MECs along with reactor components is provided for a comprehensive description of the technology. Methane production using hydrogen evolution reaction and nanocatalysts has also been discussed.

Microbial Electrolysis Cells for Electromethanogenesis: Materials, Configurations and Operations

( Mohammad Mahasin Ali ),( Sokhee P. Jung ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Anaerobic digestion is a traditional method of producing methane-containing biogas by utilizing the methanogenic conversion of organic matter like agricultural waste and animal excreta. Recently, the application of microbial electrolysis cell (MECs) technology to a traditional anaerobic digestion system has been extensively studied to find new opportunities in increasing wastewater treatability and methane yield and producing valuable chemicals. The finding that both anodic and cathodic bacteria can synthesize methane has led to the efforts of optimizing multiple aspects like microbial species, formation of biofilms, substrate sources and electrode surface for higher production of the combustible compound. MECs are very fascinating because of its ability to uptake a wide variety of raw materials including untreated wastewater (and its microbial content as biocatalysts). Methane is generally detected in MECs during the hydrogen production stage due to the growth of methanogens and generation of methane varies with shift in inoculum, substrate, and reactor design. This review is dedicated to explaining the operating principles and mechanism of the MECs for electromethanogenesis using different biochemical pathways. Emphasis on single- and double-chambered MECs along with reactor components is provided for a comprehensive description of the technology. Methane production using hydrogen evolution reaction and nano-catalysts has also been discussed.