Green Conversion Processes of Waste and Biomass Materials

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

Deadline for manuscript submissions: 31 December 2025 | Viewed by 1740

Special Issue Editors


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Guest Editor
Central Laboratory for Testing, Institute for Technology of Nuclear and Other Mineral Raw Materials, 11000 Belgrade, Serbia
Interests: biomass conversion; biochar and hydrochar production; environmental protection; waste management; biosorption

E-Mail Website
Guest Editor
Central Laboratory for Testing, Institute for Technology of Nuclear and Other Mineral Raw Materials, 11000 Belgrade, Serbia
Interests: waste biomass utilization; thermochemical technologies; hydrothermal carbonization; carbon materials; biofuel
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Central Laboratory for Testing, Institute for Technology of Nuclear and Other Mineral Raw Materials, 11000 Belgrade, Serbia
Interests: biosorption; material characterization; biomass application; biomass conversion; waste management; wastewater purification
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Our society is currently facing significant challenges related to waste disposal, which are exacerbated by population growth. Traditional waste management methods—such as composting, incineration, and open dumping—contribute to environmental pollution, economic losses, and health issues. Every day, a large volume of waste and biomass is deposited in landfills, while it could be utilized for various beneficial purposes. However, biomass typically has low stability and energy potential, along with high hygroscopicity, making its utilization less efficient.

Recent advancements have successfully transformed waste biomass into innovative, multifunctional products. By utilizing green conversion methods, such as biological and thermochemical processes, we are effectively turning waste into valuable resources with a wide range of applications. This approach not only addresses waste management challenges but also contributes to sustainable development.

This Special Issue on “Green Conversion Processes of Waste and Biomass Materials” seeks high-quality works focusing on promote the recycling of solid waste through the conversion of waste and biomass to new and useful products. Topics include, but are not limited to, methods and/or applications in the following areas:

  • Biological conversion of waste and biomass (e.g., anaerobic digestion, fermentation);
  • Thermochemical processes (e.g., hydrothermal carbonization, pyrolysis);
  • Other processes that include environmentally friendly approaches;
  • Characterization and/or utilization of new products obtained from green conversion processes.

We hope you consider participating in this Special Issue.

Sincerely,

Dr. Marija Koprivica
Dr. Jelena Petrović
Dr. Marija Simic
Guest Editors

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. Processes 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 2400 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

  • recycling of solid waste and biomass
  • conversion of waste into new and useful products
  • biological conversion
  • thermochemical conversion
  • other eco-friendly processes

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Published Papers (2 papers)

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Research

16 pages, 3156 KiB  
Article
Adsorptive Behavior of Corn-Cob- and Straw-Derived Biochar for Polycyclic Aromatic Hydrocarbon Removal from Aqueous Systems
by Jelena Beljin, Marijana Kragulj Isakovski, Jasmina Agbaba, Maja Vujić, Snežana Maletić and Aleksandra Tubić
Processes 2025, 13(5), 1521; https://doi.org/10.3390/pr13051521 - 15 May 2025
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Abstract
This study investigates the potential of biochar derived from agricultural residues—corn cob and wheat straw—for removing polycyclic aromatic hydrocarbons (PAHs) from aqueous systems. Biochars were produced via pyrolysis at 700 °C and characterized using BET, SEM, EDS, FTIR, and pXRD to evaluate physicochemical [...] Read more.
This study investigates the potential of biochar derived from agricultural residues—corn cob and wheat straw—for removing polycyclic aromatic hydrocarbons (PAHs) from aqueous systems. Biochars were produced via pyrolysis at 700 °C and characterized using BET, SEM, EDS, FTIR, and pXRD to evaluate physicochemical properties. Adsorption experiments with naphthalene, fluorene, fluoranthene, and pyrene revealed high adsorption affinities (Log Kd = 4.35–5.69 L/kg), with Freundlich isotherm modeling indicating nonlinear behavior (n = 0.732–0.923), suggesting a combination of pore filling and chemical interactions such as π-π stacking and hydrogen bonding. Corn-cob biochar, rich in lignin, exhibited a higher surface area (111 m2/g) and greater affinity for fluorene, while wheat-straw biochar, with a higher oxygen content and more functional groups, performed better for naphthalene and pyrene. FTIR and pXRD confirmed aromatic and graphitic structures facilitating PAH interactions. These results underscore the importance of feedstock selection and pyrolysis conditions in tailoring biochar properties for specific pollutants. While both biochars compare favorably with conventional adsorbents like activated carbon, further research on long-term stability in complex matrices is needed. Overall, the findings support the development of cost-effective, scalable, and eco-friendly biochar-based technologies for water remediation. Full article
(This article belongs to the Special Issue Green Conversion Processes of Waste and Biomass Materials)
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23 pages, 3222 KiB  
Article
Optimizing the Enzymatic Hydrolysis of Bioflocculated Microalgae for Bioethanol Production
by Viviane Simon, João Felipe Freitag, Júlia Lorenzato da Silva and Luciane Maria Colla
Processes 2025, 13(2), 364; https://doi.org/10.3390/pr13020364 - 28 Jan 2025
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Abstract
Spirulina platensis is a promising microalga, but biomass harvesting remains a challenge. Fungal bioflocculation offers a potential solution, facilitating the production of valuable bioproducts like bioethanol. Effective cell disruption methods, including physical-chemical and enzymatic treatments, can enhance biomass utilization. However, commercial enzymes are [...] Read more.
Spirulina platensis is a promising microalga, but biomass harvesting remains a challenge. Fungal bioflocculation offers a potential solution, facilitating the production of valuable bioproducts like bioethanol. Effective cell disruption methods, including physical-chemical and enzymatic treatments, can enhance biomass utilization. However, commercial enzymes are not optimized for microalgae, necessitating research on ideal operational conditions. This study evaluated physical and enzymatic processes to hydrolyze bioflocculated microalgae for bioethanol production. The microalga was harvested using a fungal bioflocculant produced via submerged fermentation. Biomass hydrolysis involved physical methods (autoclaving, ultrasound + autoclaving, ultrasound + gelatinization, and gelatinization) combined with enzymes (amylase, amyloglucosidase, cellulase, and xylanase), optimized for pH, temperature, and enzyme load. Hydrolysates were then used for bioethanol production. Results showed a microalgae harvest efficiency of 99.7% with a 1:8 fungus-to-microalgae ratio. Enzyme optimization identified ideal conditions (e.g., pH 4.5; 60 °C for amylase/amyloglucosidase, 70 °C for cellulase, and 50 °C for xylanase). Combined enzymatic treatments achieved approximately 70% hydrolysis efficiency, yielding 19.06 g/L glucose and 7.29 g/L ethanol (~79% conversion). Ethanol productivity was ~0.6 g per 1 g bioflocculated biomass L−1·hr. These findings highlight the potential of enzymatic hydrolysis for complex biomasses, although further studies are needed to refine enzyme applications for better biomass utilization. Full article
(This article belongs to the Special Issue Green Conversion Processes of Waste and Biomass Materials)
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