Innovations in Gaseous, Liquid and Solid Products during Biogas Generation and Utilization

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 1227

Special Issue Editors

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Guest Editor
Department of Biotechnology, Faculty of Life Sciences, University of Applied Sciences (HAW-Hamburg), 21030 Hamburg, Germany
Interests: anaerobic waste water treatment; anaerobic solid waste treatment; hygienic aspects; microbiome studies; batch and continuous biogas fermentation with energy crops and agricultural residues; fermentation analytics; trace elements; consultancy of biogas plant operators; fuzzy logic control; MilliGascounter (patents)

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Guest Editor
Department of Energy Systems Engineering, Dean of Faculty of Engineering, Koforidua Technical University, Koforidua P.O. Box KF981, Ghana
Interests: anaerobic digestion of agricultural residues and energy crops; waste-to-energy; wastewater treatment; batch and continuous fermentation; fermentation analytics; trace elements; climate protection; bioenergy resources assessment

Special Issue Information

Dear Colleagues,

The number of full-scale biogas plants is continuously increasing worldwide, especially in Germany, with approximately 9800 biogas plants. Biogas technology is not just an energy technology, but an environmental technology as well. It can sanitize and detoxify fecal material such as livestock manure, and the digestates can be used as fertilizer or as a base for humus formation. Digestate, in turn, can be transformed into biochar, but this manufacturing process is not within the scope of this Special Issue. Straw, grass, polluting algae, water hyacinths, wild flowers, municipal biowaste and even restaurant leftovers can also be used as input. In parallel, the question arises as to which waste materials can be best used in a given country without competing with land use for food production. The microbiology in the fermentation reactor also needs attention. Biogas is unique, CO2 neutral or, in some coupled processes, even CO2 negative, but sometimes the greenhouse gas balance is challenged. Therefore, articles about the GHG balance are also welcomed. The purified gaseous product, biomethane, is the only one that embodies the three types of energy: electricity, heat and fuel. The biogas can be compressed and used in a decentralized manner. Many countries have a gas grid for conventional sources such as fossil gas, which could serve as a huge energy battery to store biomethane. A country like Denmark, for example, has set itself the goal of becoming completely independent of gas imports in the next decade through biomethane. By producing electricity in a central heating power plant, heat can be used as byproduct. This leads to the highest conversion efficiency of about 90% in renewables, which is feasible. In times of resource dependency, gas is becoming increasingly important as a directly usable product (including the use of CO2 in pure form for industrial purposes). Anaerobic degradation processes also concentrate salts; the effluent products ammonium and H2S could represent a severe environmental and technical problem. In some regions, the use of digestates as fertilizers is limited, while in other regions it is highly recommended. Therefore, there are developments in densely populated areas to refine fermentation residues to produce humus formers, transportable inorganic salts as fertilizers and potable water. Therefore, manuscripts on these topics are also welcomed.

Prof. Dr. Paul A. Scherer
Prof. Dr. Richard Arthur
Guest Editors

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  • emissions
  • greenhouse gases
  • effluents
  • biogas plants
  • digestates
  • fertilizers
  • biomethane

Published Papers (1 paper)

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16 pages, 2234 KiB  
Restoring the Stability of Long-Term Operated Thermophilic Anaerobic Digestion of Maize Straw by Supplying Trace Elements
by Bridget Ataa Fosua, Lijuan Ren, Wei Qiao, Jiahao Zhang, Yanning Gao, Xianli Fu, Dunyao Yu and Renjie Dong
Processes 2023, 11(12), 3440; - 16 Dec 2023
Viewed by 682
Maize straw has been widely used for the production of energy through anaerobic digestion, but biogas production can be hindered by a lack of trace elemental nutrients. To address this issue, a lab-scale anaerobic plug flow reactor was continuously operated at 55 °C [...] Read more.
Maize straw has been widely used for the production of energy through anaerobic digestion, but biogas production can be hindered by a lack of trace elemental nutrients. To address this issue, a lab-scale anaerobic plug flow reactor was continuously operated at 55 °C for 300 days, with a hydraulic retention time of 42 days and an organic loading rate of 2.1 g total solids/(L·day). Results from this study showed that between days 101 and 194, the methane yield slightly decreased from 0.26 ± 0.04 to 0.24 ± 0.03 L/g volatile solids (VS), but significant volatile fatty acid accumulation was observed by reaching up to 2759 ± 261 mg/L. After trace elements were added to the reactor, the methane yield increased to 0.30 ± 0.03 L/g VS, with 53% methane content. Around 62% of the total chemical oxygen demand and volatile solids were broken down into methane. Volatile fatty acid levels dropped and stabilized at around 210 ± 50 mg/L, indicating restored process stability. The addition of trace elements increased the abundance of Firmicutes and decreased Synergistetes in bacteria while simultaneously increasing the abundance of Methanosarcina in archaea. In conclusion, trace element supplementation was experimentally found to be necessary for stable thermophilic anaerobic digestion of maize straw. Full article
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