Advanced Routes of Biological and Bio-electrocatalytic Carbon Dioxide (CO<inf>2</inf>) Mitigation Toward Carbon Neutrality

Changes in the environment due to multiple factors, such as combustion of fossil fuels, heating, transportation, deforestation, etc., have led to more greenhouse gases in the atmosphere, which eventually led to a rise in global temperatures. Carbon dioxide (CO2) is the major factor for the rapid rise in global temperature. One of the most encouraging technological advances to address global warming is to transform CO2 into value-added commodities that offer a win–win strategy. In this regard, intensive research has been pursued around the world for development of feasible systems in product recovery or product synthesis from CO2-rich industrial emissions. We envision that the biological CO2 reduction or conversion process can be beneficial for developing carbon-neutral technologies. The integration of CO2-emitting industrial technologies with CO2-converting biological systems can be helpful in achieving sustainable value-added products with no or minimal loss of energy and materials that are assuring for improved economics. The CO2-converting bioprocesses can be directly integrated with the processes emitting a high amount of CO2. This symbiotic integration can make the whole process carbon neutral. Herein, this review highlights an insight on research activities of biological CO2 mitigation using photo catalysts (algae and photo bacteria), an anaerobic biocatalyst (bacteria), gas fermentation, and an enzymatic catalyst. Perspectives and challenges of these technologies are discussed

Exploitation of Citrus Peel Extract as a Feedstock for Power Generation in Microbial Fuel Cell (MFC)

Microbial fuel cells (MFCs) are envisioned as an evolving cost-effective process for treating organic wastes to simultaneously generate bioelectricity. Therefore, in present study a single chambered mediator- less air cathode MFC was operated for bioelectricity generation using citrus waste (CW) as a feedstock. The MFC was operated at four organic loading conditions (OLs; 3, 6, 9 and 12 kg/m3). The voltage generation and organic content reduction demonstrated the possibility of utilizing CW as a substrate in MFC. The polarization analysis revealed a high-power generation of 71.1 mW/m2 with low OL of 3 kg/m3. The decrease in pH and high volatile fatty acids (VFAs) generation was noted at high OL. Our current findings suggest better performance of MFC, in terms of energy generation and organic reduction at high OL.This research was supported by Brain Pool Grant (NRF-2019H1D3A2A01060226) by National Research Foundation of Korea to work at Konkuk University (VCK). This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2013M3A6A8073184). This research was supported by 2018 KU Brain Pool of Konkuk University.Scopu

Methane as a Substrate for Energy Generation Using Microbial Fuel Cells

Methane (CH 4 ) is a well-known and abundant feedstock for natural gas, and is readily available from various sources. In thermal plants, the CH 4 generated from anthropogenic sources is converted into electrical energy via combustion. Microbial fuel cell (MFC) technology has proven to be an efficient strategy for the biological conversion of a many substrates, including biogas (CH 4 ), to electricity. MFC technology uses gaseous substrate along with an enriched and selective microbial consortium. Predominantly, methanotrophs and electrochemically active Geobacter were utilized in a syntrophic association on the anode of an MFC. This review focuses on the exploitation of CH 4 as a substrate for bioelectrogenesis via MFCs.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2018H1D3A2001746, 2013M3A6A8073184). This work was supported by the Energy Efficiency & Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20153030091450). This research was supported by 2017 KU Brain Pool of Konkuk University.Scopu

Efficiency of air-dried and freeze-dried alginate/xanthan beads in batch, recirculating and column adsorption processes

Alginate (Alg) beads are low-cost adsorbents used for wastewater remediation. In this work, alginate (Alg) and alginate/xanthan (Alg/XG) blend beads were synthesized by gelation method into calcium chloride and freezedried to improve the porosity. Their adsorption efficiency was tested for methylene blue (MB) dye in batch, recirculating and column adsorption systems. The blend beads were characterized using by SEM, FTIR-ATR and X-ray microcomputer tomography (Micro-CT) analyzes. Freeze-dried Alg and Alg/XG beads presented porosity of 46 +/-&amp; nbsp;5% and 77 &amp; nbsp;+/- 3%, respectively. Adsorption isotherms of MB on freeze-dried Alg/XG beads indicated better adsorption capacity in comparison to the air-dried ones. Adsorption kinetics and breakthrough curves based on recirculating and vertical column adsorption processes of MB on freeze dried Alg/XG and air-dried Alg/XG beads indicated higher efficiency for the vertical column system packed with freeze dried Alg/XG beads. The removal efficiency of 91% MB by the freeze-dried Alg/XG beads in vertical column remained even after four consecutive adsorption-desorption cycles, disclosing these beads as potential systems for the wastewater treatment

Utilization of residual organics of Labaneh whey for renewable energy generation through bioelectrochemical processes: Strategies for enhanced substrate conversion and energy generation

Labaneh whey (LW)that is rich in residual organics was evaluated for bioelectricity generation using microbial fuel cell (MFC)in two different configurations namely single chamber (MFC-SC)and dual chamber (MFC-DC)MFCs. The whole study was executed in three stages: The first stage evidenced promising amount of bioelectricity generation (DC, 643 mV; SC, 545 mV)along with chemical oxygen demand removal (CODr: DC, 60.63%; SC, CODr: 55.25%). In the second phase, activity of anodic electrogenic microbes was improved with short time poising at potentials of 400, 600 and 800 mV, among which 800 mV evidenced 2.24 (DC)and 1.60 (SC)fold enhancement in power generation along with significant improvement in substrate degradation. The third phase was solely focused on bioelectrochemical treatment of LW through applied potentials for extended period. This phase achieved 89 and 94% chemical oxygen demand (COD)degradation using SC and DC configurations, respectively at 800 mV. - 2019 Elsevier LtdThis publication was made possible by NPRP grant # 6-289-2-125 from the Qatar national research fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Appendix AScopu