Special Issue "Anaerobic Fermentation – a Biological Route towards Achieving Net Neutrality"

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Industrial Fermentation".

Deadline for manuscript submissions: 30 November 2022 | Viewed by 3356

Special Issue Editor

Dr. Sanjay Nagarajan
E-Mail Website
Guest Editor
1. Lecturer in Chemical Engineering, Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK
2. Visiting Scholar, School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, Northern Ireland, UK
Interests: biomass pre-treatment; anaerobic digestion; biorefinery; hydrodynamic cavitation; photocatalysis; advanced oxidation processes

Special Issue Information

Dear Colleagues,

The international community adopted the Paris Agreement in 2015 to address climate change by keeping the increase in the mean global temperature to less than 2 ℃ above pre-industrial levels. The increase in mean global temperature is directly linked to the green house gas emissions leading to global warming. Therefore, a strong emphasis was put on net neutrality in the Paris Agreement, followed by its secondment in the recently concluded COP26. To achieve net neutrality, a sustainable circular economy approach is preferred. Amongst the available options, biological routes and especially the ‘Anaerobic Fermentation’ route have immense potential to contribute to net neutrality. This ranges from the production of biogas, biohythane, biohydrogen, or volatile fatty acids from anaerobic digestion to classical alcohol/solvent fermentation for the production of biobased solvents and biofuels, such as bioethanol and biobutanol. Beyond these products, novel high-value biorenewable platform chemicals can also be produced via ‘Anaerobic Fermentation’, thereby maximising their potential. In contrast to conventional feedstocks, to support a circular economy it is paramount that the current generation of ‘Anaerobic Fermentation’ focuses on organic wastes/waste gas streams as feedstocks to produce these products to enable net neutrality.

This Special Issue will therefore exclusively focus on innovative research outputs, short communications, and perspective reviews on the production of biofuels and high-value biorenewables via anaerobic fermentation to support net neutrality. The use of biomass pre-treatments to support/enhance fermentation product yields are also of interest. Full-length review articles are also encouraged, but the authors are required to contact the editor to discuss the topic before submission.

Dr. Sanjay Nagarajan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fermentation is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • anaerobic digestion
  • biogas
  • biohydrogen
  • biohythane
  • biomass pre-treatment
  • volatile fatty acids
  • gas fermentation
  • high value chemicals (renewable)
  • renewable platform chemicals
  • anaerobic biorefineries
  • microbial electrosynthesis
  • life cycle assessment
  • techno-economic analysis

Published Papers (5 papers)

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Research

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Article
Shaping an Open Microbiome for Butanol Production through Process Control
Fermentation 2022, 8(7), 333; https://doi.org/10.3390/fermentation8070333 - 15 Jul 2022
Viewed by 383
Abstract
The growing awareness of limited resource availability has driven production systems towards greater efficiencies, and motivated the transition of wastewater treatment plants to water resource recovery facilities. Open microbiome fermentation offers a robust platform for resource recovery, due to its higher metabolic versatility, [...] Read more.
The growing awareness of limited resource availability has driven production systems towards greater efficiencies, and motivated the transition of wastewater treatment plants to water resource recovery facilities. Open microbiome fermentation offers a robust platform for resource recovery, due to its higher metabolic versatility, which is capable of dealing with even dilute residual liquid streams. Organic matter, e.g., fatty acids, lost in these streams can potentially be recovered into higher value chemicals such as alcohols. This study aims to shape an open microbiome towards butanol production from butyrate and hydrogen through pH control and continuous hydrogen supply. Two sets of experiments were conducted in Scott bottles (1 L) and a lab-fermenter (3 L). The open microbiome produced up to 4.4 mM butanol in 1 L bottles. More promising conversions were obtained when up-scaling to a lab-fermenter with pH control and an increased hydrogen partial pressure of 2 bar; results included a butanol concentration of 10.9 mM and an average volumetric productivity of 0.68 mmol L−1 d−1 after 16 days. This corresponds to 2.98- and 4.65-fold increases, respectively, over previously reported values. Thermodynamic calculations revealed that product formation from butyrate was unfeasible, but energetically favorable from bicarbonate present in the inoculum. For the first time, this study provides insights regarding the community structure of an open microbiome producing butanol from butyrate and hydrogen. DNA sequencing combined with 16S rRNA gene amplicon analysis showed high correlation between Mesotoga spp. and butanol formation. Microbial diversity can also explain the formation of by-products from non-butyrate carbon sources. Full article
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Article
Sequencing Batch Reactor Performance Evaluation on Orthophosphates and COD Removal from Brewery Wastewater
Fermentation 2022, 8(7), 296; https://doi.org/10.3390/fermentation8070296 - 23 Jun 2022
Viewed by 428
Abstract
The discharge of industrial effluent constituting high orthophosphates and organic pollutants in water receiving bodies compromises freshwater quality and perpetuates eutrophication. In this study, an anaerobic–aerobic sequencing batch reactor (SBR) under activated sludge was investigated for orthophosphates and chemical oxygen demand (COD) removal [...] Read more.
The discharge of industrial effluent constituting high orthophosphates and organic pollutants in water receiving bodies compromises freshwater quality and perpetuates eutrophication. In this study, an anaerobic–aerobic sequencing batch reactor (SBR) under activated sludge was investigated for orthophosphates and chemical oxygen demand (COD) removal from brewery wastewater. Raw brewery wastewater samples were collected on a daily basis for a period of 4 weeks. The findings of the study are reported based on overall removal efficiencies recording 69% for orthophosphates and 54% for total COD for a sludge retention time (SRT) of 7 days and hydraulic retention time of 18 h at mesophilic temperature conditions of ±25 °C. Moreover, the SBR system showed stability on orthophosphate removal at a SRT ranging from 3 to 7 days with a variation in organic volumetric loading rate ranging from 1.14 to 4.83 kg COD/m3.day. The anaerobic reaction period was experimentally found to be 4 h with the aerobic phase lasting for 14 h. The SBR system demonstrated feasibility on orthophosphates and COD removal with variation in organic loading rate. Full article
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Article
Increasing Anaerobic Digestion Efficiency Using Food-Waste-Based Biochar
Fermentation 2022, 8(6), 282; https://doi.org/10.3390/fermentation8060282 - 16 Jun 2022
Viewed by 538
Abstract
The efficiency of methane production by anaerobic digestion (AD), during which energy is generated from organic waste, can be increased in various ways. Recent research developments have increased the volume of gas production during AD using biochar. Previous studies have used food waste [...] Read more.
The efficiency of methane production by anaerobic digestion (AD), during which energy is generated from organic waste, can be increased in various ways. Recent research developments have increased the volume of gas production during AD using biochar. Previous studies have used food waste itself in AD, or, added wood-biochar or sewage sludge charcoal as an accelerant of the AD process. The application of food-waste biochar in AD using activated sludge has not yet been studied and is considered a potential method of utilizing food waste. Therefore, this study investigated the use of biochar prepared by the thermal decomposition of food waste as an additive to AD tanks to increase methane production. The addition of food-waste biochar at 1% of the digestion tank volume increased the production of digestion gas by approximately 10% and methane by 4%. We found that food-waste biochar served as a medium with trace elements that promoted the proliferation of microorganisms and increased the efficiency of AD. Full article
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Article
Microbial Communities in Underground Gas Reservoirs Offer Promising Biotechnological Potential
Fermentation 2022, 8(6), 251; https://doi.org/10.3390/fermentation8060251 - 26 May 2022
Cited by 1 | Viewed by 754
Abstract
Securing new sources of renewable energy and achieving national self-sufficiency in natural gas have become increasingly important in recent times. The study described in this paper focuses on three geologically diverse underground gas reservoirs (UGS) that are the natural habitat of methane-producing archaea, [...] Read more.
Securing new sources of renewable energy and achieving national self-sufficiency in natural gas have become increasingly important in recent times. The study described in this paper focuses on three geologically diverse underground gas reservoirs (UGS) that are the natural habitat of methane-producing archaea, as well as other microorganisms with which methanogens have various ecological relationships. The objective of this research was to describe the microbial metabolism of methane in these specific anoxic environments during the year. DNA sequencing analyses revealed the presence of different methanogenic communities and their metabolic potential in all sites studied. Hydrogenotrophic Methanobacterium sp. prevailed in Lobodice UGS, members of the hydrogenotrophic order Methanomicrobiales predominated in Dolní Dunajovice UGS and thermophilic hydrogenotrophic members of the Methanothermobacter sp. were prevalent in Tvrdonice UGS. Gas composition and isotope analyses were performed simultaneously. The results suggest that the biotechnological potential of UGS for biomethane production cannot be neglected. Full article
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Review

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Review
Intensification of Acidogenic Fermentation for the Production of Biohydrogen and Volatile Fatty Acids—A Perspective
Fermentation 2022, 8(7), 325; https://doi.org/10.3390/fermentation8070325 - 11 Jul 2022
Viewed by 509
Abstract
Utilising ‘wastes’ as ‘resources’ is key to a circular economy. While there are multiple routes to waste valorisation, anaerobic digestion (AD)—a biochemical means to breakdown organic wastes in the absence of oxygen—is favoured due to its capacity to handle a variety of feedstocks. [...] Read more.
Utilising ‘wastes’ as ‘resources’ is key to a circular economy. While there are multiple routes to waste valorisation, anaerobic digestion (AD)—a biochemical means to breakdown organic wastes in the absence of oxygen—is favoured due to its capacity to handle a variety of feedstocks. Traditional AD focuses on the production of biogas and fertiliser as products; however, such low-value products combined with longer residence times and slow kinetics have paved the way to explore alternative product platforms. The intermediate steps in conventional AD—acidogenesis and acetogenesis—have the capability to produce biohydrogen and volatile fatty acids (VFA) which are gaining increased attention due to the higher energy density (than biogas) and higher market value, respectively. This review hence focusses specifically on the production of biohydrogen and VFAs from organic wastes. With the revived interest in these products, a critical analysis of recent literature is needed to establish the current status. Therefore, intensification strategies in this area involving three main streams: substrate pre-treatment, digestion parameters and product recovery are discussed in detail based on literature reported in the last decade. The techno-economic aspects and future pointers are clearly highlighted to drive research forward in relevant areas. Full article
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