Advanced Bioconversion and Valorization of Organic Solid Waste

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

Deadline for manuscript submissions: 10 September 2026 | Viewed by 1150

Special Issue Editor

State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, China
Interests: waste-activated sludge; food waste; anaerobic fermentation; volatile fatty acids
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The rapid increase in organic solid waste generation, particularly waste-activated sludge and food waste, presents a critical challenge for global urbanization and environmental sustainability. While traditional disposal methods focus on volume reduction and stabilization, the paradigm is shifting towards a circular economy approach. In this context, organic solid waste is increasingly regarded as a renewable reservoir of nutrients and carbon sources. Consequently, developing efficient and sustainable technologies for the high-value valorization of these waste streams has become a priority.

Anaerobic fermentation and digestion have been widely recognized as core technologies for organic solid waste treatment. Beyond traditional methane production, recent research trends are pivoting towards the recovery of higher-value products. These include, but are not limited to, short-chain fatty acids, medium-chain fatty acids, hydrogen and single-cell protein. However, the bioconversion efficiency is often restricted by rate-limiting steps such as hydrolysis, thermodynamic constraints and complex metabolic intermediates.

To address these challenges, novel strategies, such as advanced pretreatment methods, co-fermentation strategies and bio-augmentation, are being developed. Furthermore, since these transformations are fundamentally biological processes, understanding the functional microorganisms and their metabolic networks is crucial. Uncovering the underlying mechanisms via multi-omics approaches (metagenomics, metatranscriptomics, etc.) is urgent for optimizing process stability and yield.

We are inviting research papers and reviews that provide novel insights into the high-value fermentation and conversion of organic solid waste. The aim of this Special Issue is to highlight the latest findings in converting substrates like sludge and food waste into bioenergy and biochemicals.

Topics of interest include, but are not limited to:

  • Production of short-chain fatty acids, medium-chain fatty acids, hydrogen, methane and single-cell protein from organic solid waste.
  • Novel pretreatment and conditioning technologies to enhance bioavailability.
  • Synergistic effects and mechanisms in the co-fermentation of sludge and food waste.
  • Regulation of metabolic pathways for directional product recovery.
  • Microbial community assembly and functional analysis in fermentation systems.
  • Techno-economic analysis and life cycle assessment of high-value conversion processes.

Dr. Yang Wu
Guest Editor

Manuscript Submission Information

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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.

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Keywords

  • organic solid waste
  • waste activated sludge
  • food waste
  • anaerobic fermentation
  • short-chain fatty acid
  • methane

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Published Papers (1 paper)

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Research

13 pages, 1645 KB  
Article
Promoting Smithella Enrichment, Syntrophic Interaction and Metabolism for Efficient Anaerobic Conversion of Propionate to Methane: The Role of Lys@Fe3O4
by Yu Su, Haojin Peng, Leiyu Feng and Yinguang Chen
Fermentation 2026, 12(3), 161; https://doi.org/10.3390/fermentation12030161 - 18 Mar 2026
Viewed by 890
Abstract
The bioconversion of propionate, a well-known intermediate of anaerobic digestion (AD), to methane is energetically unfavorable under standard conditions, which typically occurs in the syntrophy of bacteria and methanogens via methylmalonyl-CoA (MMC) and the dismutation pathway. Since the latter, which is reported only [...] Read more.
The bioconversion of propionate, a well-known intermediate of anaerobic digestion (AD), to methane is energetically unfavorable under standard conditions, which typically occurs in the syntrophy of bacteria and methanogens via methylmalonyl-CoA (MMC) and the dismutation pathway. Since the latter, which is reported only in Smithella, possessed a thermodynamic advantage over the former, enriching Smithella and promoting the syntrophic interaction and metabolism of the microbiota are important for improving AD efficiency. In this study, lysine-modified Fe3O4 (Lys@Fe3O4) significantly enhanced the bioconversion of propionate to methane. The methane yield and the maximum methane production rate (Rmax) in a Lys@Fe3O4 reactor were 278.7% and 271.7% of Blank, and the corresponding values were 201.9% and 201.6% of bare Fe3O4, respectively. The metaproteomic results indicated that Lys@Fe3O4 increased not only the abundance of Smithella but also the expression of cell surface and adhesion proteins, thereby promoting syntrophic interaction between Smithella and methanogens and facilitating electron and acetate transfer from Smithella to methanogens. Moreover, the expression of quorum-sensing proteins was enhanced, benefiting the cooperation of Smithella and its associated bacterium (Syntrophomonas). Furthermore, the expressions of key enzymes related to metabolism and electron transfer in propionate oxidation, butyrate oxidation, CO2-reductive methanogenesis and acetoclastic methanogenesis were all significantly upregulated. The results are of great significance for maintaining low propionate concentration and stability of AD. Full article
(This article belongs to the Special Issue Advanced Bioconversion and Valorization of Organic Solid Waste)
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