Submit to Special Issue Submit Abstract to Special Issue Review for Sustainability Propose a Special Issue

Journal Menu

Journal Browser

► Journal Browser

Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition

Special Issue Editors
Special Issue Information
Keywords
Benefits of Publishing in a Special Issue
Published Papers

A special issue of Sustainability (ISSN 2071-1050).

Deadline for manuscript submissions: 31 December 2026 | Viewed by 5974

Share This Special Issue

Special Issue Editors

Dr. Carlos Miguel Henriques Ferreira

E-Mail Website
Guest Editor

1. CBQF—Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
2. Amyris Bio Products Portugal Unipessoal Lda, 4169-005 Porto, Portugal
Interests: waste valorization; protein and peptides; bioinorganic chemistry; green chemistry; cheminformatics
Special Issues, Collections and Topics in MDPI journals

Dr. Sara Nunes Silva

E-Mail Website
Guest Editor

CBQF—Centro de Biotecnologia e Química Fina—Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
Interests: delivery systems; byproduct valorization; bioactive ingredients; antimicrobials; nutraceuticals; bioactives; immunomodulation
Special Issues, Collections and Topics in MDPI journals

Dr. Catarina Silva S. Oliveira

E-Mail Website
Guest Editor

CBQF—Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
Interests: biological valorization of wastes; fractionation of wastes and purification of components to produce platform chemicals and functional ingredients; economic viability of waste valorization processes
Special Issues, Collections and Topics in MDPI journals

Dr. Alessandra Braga Ribeiro

E-Mail Website
Guest Editor

Faculty of Biotechnology, CBQF—Centre of Biotechnology and Fine Chemistry, Associate Laboratory, Catholic University of Portugal, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
Interests: polymers from natural source; synthesis and characterization of hydrogels based on natural polysaccharides; nanostructured materials based on biopolymers; extraction, purification and valorization of polysaccharides and bioactive compounds from residues and byproducts
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The world is facing an ever-increasing pressure on its natural resources, aggravated by the increasing consumer demands for new and more affordable bioactive products. On top of that, environmental awareness and concern by the public in general demands a shift in production strategies for new valuable products for high-value markets, such as cosmetic or nutraceutical products. The valorization of by-products and waste products is an attractive and compelling strategy, giving rise to new products while complying with the ideas of the circular economy.

Considering these points, this Special Issue aims to explore the field of by-product valorization processes for the development of sustainable products for high-value markets and the utilization of old and new by-products and waste streams from various industries to create value-added products for growing markets. Evaluation of explored strategies by means of green and sustainability metrics is highly encouraged, thus providing solid grounds on the sustainability claims of evaluated strategies.

The scope of this Special Issue will encompass the examination of different valorization processes, their potential applications, and their environmental impact assessment using green metrics. The topics of interest for this Special Issue include, but are not limited to, the following:

Latest advancements and novel approaches in by-product valorization within the context of high-value markets, such as, but not limited to, nutraceutical or cosmeceutical product development.
Identification of new sources of bioactive compounds, extraction techniques, formulation strategies, and quality control methods.
Evaluation of the sustainability aspects of valorization processes, emphasizing the use of green metrics.
Evaluation of environmental, economic, and social impacts of valorization processes, such as energy and material consumption, carbon footprint, waste generation, and socioeconomic benefits.
Comprehensive overview of current trends, challenges, and opportunities in the field of valorization of by-products and wastes into value-added products.

This Special Issue will thus contribute to the knowledge base by highlighting successful case studies, discussing technological advancements, and identifying future research directions grounded by objective and solid sustainability evaluation.

Therefore, we encourage all authors to contribute their original research articles, reviews, and case studies that investigate already established and innovative strategies and technologies for the efficient conversion of by-products into valuable ingredients or finished products, with particular emphasis on strategies’ evaluation by means of sustainability and green metrics.

We look forward to your submissions.

Dr. Carlos Miguel Henriques Ferreira
Dr. Sara Silva
Dr. Catarina Silva S. Oliveira
Dr. Alessandra Braga Ribeiro
Guest Editors

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 250 words) can be sent to the Editorial Office for assessment.

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. Sustainability is an international peer-reviewed open access semimonthly 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

by-product valorization
bioactive
circular economy
green chemistry
green metrics

Benefits of Publishing in a Special Issue

Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
Reprint: MDPI Books provides the opportunity to republish successful Special Issues in book format, both online and in print.

Further information on MDPI's Special Issue policies can be found here.

Published Papers (7 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

Jump to: Review

20 pages, 3537 KB

Open AccessArticle

Current Perspectives on the Sustainable Remediation of Lead-Contaminated Water Using Tomato Juice By-Products

by Iuliana-Maria Enache, Iuliana Motrescu, Irina Gabriela Cara, Miruna-Paraschiva Protea, Denis Constantin Topa, Gabriela Ungureanu and Antoanela Patras

Sustainability 2026, 18(7), 3628; https://doi.org/10.3390/su18073628 - 7 Apr 2026

Viewed by 305

Abstract

The large quantities of agri-food waste produced worldwide by the tomato processing industry require recovery. This study evaluated the efficiency of the by-product resulting from tomato juice preparation as an innovative biomaterial for removing lead from water. The pomace was dried and tested in two forms: raw (RT) and after extraction of soluble compounds (ET). The extracts obtained from the preparation of ET, could be reintroduced into the food industry (as colorants, etc.) according to the “zero waste” principle, but further studies are needed. No other chemical pre-treatment was applied to improve the lead-adsorption capacity. The pH influence, biosorbent dosage, kinetics and equilibrium were evaluated. Analytical methods, such as atomic absorption spectrometry, elemental chemical analysis, FTIR, scanning electron microscopy, and predictive models, were applied. The outcomes demonstrated a lead-adsorption efficiency of 99.22% for ET and 89.83% for RT, an optimum pH of 4.0 ± 0.5, and an initial solution containing 20 mg Pb²⁺/L. The Langmuir model predicted high removal capacities: 142.18 mg/g for ET and 90.91 mg/g for RT. Both forms of tomato pomace were efficient for sustainable and cost-effective water remediation, but an improvement was noticed after the extraction of soluble components that could be valorized in other products within the circular economy. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

19 pages, 3143 KB

Open AccessArticle

Characterization and Contaminant Assessment of Waste Tire Char Produced in an Industrial-Scale Auger Reactor

by Magdalena Joka Yildiz, Ewa Szatyłowicz, Izabela B. Zgłobicka, Güray Yildiz and Krzysztof J. Kurzydłowski

Sustainability 2026, 18(7), 3294; https://doi.org/10.3390/su18073294 - 27 Mar 2026

Viewed by 534

Abstract

This work investigates the physicochemical characteristics of waste tire pyrolysis char (WTP-char) produced at 500 °C in an industrial-scale auger reactor. The study uniquely combines material profiling with environmental safety assessment, specifically targeting organic contaminants and polymer stabilizers, evaluating WTP-char’s potential for circular economy applications. The samples underwent comprehensive analysis, including GC-MS, TGA, SEM-EDS, TXRF, and BET surface area measurements. The results revealed a high volatile matter content (13 wt.%), attributed to the thermal inertia typical of industrial-scale units. The organic fraction was dominated by n-alkanes (48.3%) and a significant concentration (6.97%) of the stabilizer Tris(2,4-di-tert-butylphenyl) phosphate (bDtBPP), posing potential environmental risks due to its cytotoxicity. Polycyclic aromatic hydrocarbon (PAH) analysis showed a prevalence of high-molecular-weight (HMW) compounds (79.7%), indicating high chemical stability. Although the specific surface area was low (28.9 m²/g), suggesting the need for activation, the material exhibits potential as a low-cost semi-reinforcing filler or solid fuel. By moving beyond laboratory-scale experiments to real industrial production, this study establishes a practical framework for evaluating both the performance and environmental safety of waste tire pyrolysis char. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

23 pages, 1563 KB

Open AccessArticle

Sustainable Lipase Immobilization on Eggshell Membrane Carriers: Economic and LCA Insights at Laboratory Scale

by Marija Stjepanović, Marta Ostojčić, Ivica Strelec, Natalija Velić, Nghiep Nam Tran, Volker Hessel, Marc Escribà-Gelonch and Sandra Budžaki

Sustainability 2026, 18(1), 134; https://doi.org/10.3390/su18010134 - 22 Dec 2025

Viewed by 674

Abstract

This study presents a comprehensive economic and environmental evaluation of immobilized lipases produced on eggshell membrane-based carriers from eggshell waste, based on laboratory-scale experiments. By integrating economic analysis (EA) and life cycle analysis (LCA), the key factors affecting the economic viability and environmental impact of the process were identified, supporting sustainable and circular biorefinery concepts. The EA estimated the total process cost at EUR 25.63 for 15 g of product, while the effective net cost was negative (EUR −14.81) due to the valorization of anhydrous calcium chloride as a valuable by-product. The effective net cost reduction from by-product valorization of the immobilized lipase was estimated at 0.99 EUR/g as the minimum selling price (MSP). When expressed per unit of enzymatic activity, the immobilized lipase on the eggshell waste membrane-based carrier shows a substantially lower cost (EUR/U) compared with representative commercial immobilized lipases, demonstrating clear catalytic cost-efficiency advantages. The cradle-to-gate life cycle assessment, conducted using ReCiPe 2016 quantification methods, highlighted electricity consumption during drying as the primary environmental hotspot, accounting for up to 57% of the global warming potential. Sensitivity and uncertainty analyses showed that energy consumption strongly influences the impact in terms of climate change and fossil resource depletion, while the impact of chemical use was minimal. These results show that energy-efficient process optimization, especially in the drying phase, is crucial for further improving environmental and economic performance. These results indicate that optimizing energy efficiency, especially during the drying phase, is crucial for further improving the production process of immobilized lipases on eggshell membrane-based carriers, both environmentally and economically. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

24 pages, 2719 KB

Open AccessArticle

Circular Perspective for Utilization of Industrial Wastewaters via Phytoremediation

by Piotr Rybarczyk, Jacek Antonkiewicz, Zdzisława Romanowska-Duda, Stanisław Mec and Andrzej Rogala

Sustainability 2025, 17(23), 10865; https://doi.org/10.3390/su172310865 - 4 Dec 2025

Viewed by 617

Abstract

Wastewater generated in municipal rendering facilities requires multi-step treatment, but it may also serve as a source of nutrients and water and thus may be valorized before or instead of the necessary wastewater treatment operations. In this work, wastewaters from a composting plant were utilized to support the growth of Miscanthus x giganteus, known as both a remediation plant and an energy biomass source. A pot experiment was established to compare the effects of different wastewater doses (0, 50, 100, and 200 mL per pot per week) on the miscanthus biomass yield, phytoextraction of heavy metals, biomass heat of combustion, and plant condition. The increase in the wastewater dose resulted in increases in both biomass yield (from about 44 to 139%) and biomass heat of combustion (from 7 to 17%) when compared to the control sample, with no adverse effects on plant physiological parameters. The highest concentrations of metals were found in miscanthus grown with the highest dose of wastewaters. It was found that higher wastewater dose correlates to both higher phytoextraction and phytorecovery of metals from plant substrate and wastewaters. The highest metal uptake was identified for Fe (431 mg·pot⁻¹), followed by Al, Zn, Mn, Cu, Ni, Cr. The lowest metal uptake was noted for Pb, Co and Cd (0.88, 0.11, and 0.95 mg·pot⁻¹, respectively). The results indicate that miscanthus can be recommended for industrial wastewater treatment. In addition, due to high absorption efficiency of the substrate components, miscanthus can be used as a remediation tool, e.g., for the ecological stabilization of remediation of metal-polluted soils, especially in municipal facilities like rendering plants. This presents a circular perspective for the valorization of post-fermentation wastewaters with subsequent growth of energy crops, with other potential benefits for the environment, such as soil treatment, absorption of CO₂, and air purification. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

15 pages, 680 KB

Open AccessArticle

Method of Management and Determination of Quality of Waste from Green Areas for the Production of Pellets Used for Fertilization Purposes

by Miłosz Zardzewiały, Katarzyna Szopka, Dariusz Gruszka, Tomasz R. Sekutowski, Marcin Bajcar, Bogdan Saletnik and Józef Gorzelany

Sustainability 2025, 17(22), 10250; https://doi.org/10.3390/su172210250 - 16 Nov 2025

Viewed by 782

Abstract

A very important issue in urban agglomerations is the proper management of green waste while reducing its negative impact on the environment. One potential solution is the utilization of green biomass—originating from the maintenance of parks, squares, and home gardens—for the production of compost and compost-based pellets as organic fertilizers. The aim of this study was to produce compost-based pellets intended for fertilization purposes from compost derived from green waste and conifer sawdust, and to analyze their mechanical and chemical properties. Ten variants of pellets with different compost-to-sawdust ratios were evaluated. Compost-based pellets exhibited the highest initial mechanical strength; however, their resistance to external loads decreased over time, whereas the best long-term stability was observed in pellets containing 50% sawdust. The seasoning process influenced the stabilization or improvement of the mechanical properties of certain mixtures. Chemical analyses showed that compost-based pellets contained the highest concentrations of nutrients (N, P, K), while increasing the proportion of sawdust reduced their fertilizing value. No exceedances of permissible heavy metal limits were detected. The results confirm the suitability of compost-based pellets made from green biomass as a sustainable alternative to mineral fertilizers, supporting the principles of the circular economy. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

20 pages, 2544 KB

Open AccessArticle

The Possibilities of Using Non-Traditional Raw Materials for Fertilizing Products

by Goda Gudinskaitė and Rasa Paleckienė

Sustainability 2025, 17(13), 5710; https://doi.org/10.3390/su17135710 - 20 Jun 2025

Cited by 2 | Viewed by 1229

Abstract

In recent years, the Green Deal has become a cornerstone of the European Union’s development strategy, aiming to establish a sustainable, innovative and environmentally friendly economy. One of its primary goals is to reduce the negative impact of intensive farming by promoting sustainable agricultural practices. These practices include replacing synthetic fertilizers with more natural alternatives and substituting chemical plant protection products with biological solutions. A noteworthy prospect in this context is the growing insect farming industry, which opens up new possibilities for the food industry via waste processing. In Lithuania, insect farming is also expanding rapidly, with companies producing several hundred tons of frass (insect excrement and residues from growing media) every year. As insect farming is projected to increase rapidly over the next decade, the amount of frass produced will also increase. Therefore, it is necessary to find sustainable ways to use this byproduct. Frass is emerging as an important area of research and practical innovation with great potential for fertilizer production. Initial studies show that frass can contain up to 6% nitrogen, 2% phosphorus and 3% potassium, making it a valuable alternative to synthetic fertilizers. The chitin content (nearly 14%) in frass not only improves the soil but also improves plant resistance to disease. In addition, its organic composition improves soil structure and microbiological activity, contributing in the long term to increasing soil fertility. This paper analyses different samples of frass, assesses their physical and chemical properties and discusses the possible applications of these products in the context of sustainable agriculture. The studies show that frass can be a valuable raw material for fertilizer production, potentially reducing the need for synthetic fertilizers and contributing to the reduction in agricultural waste. By combining economic benefits with ecological sustainability, this research contributes to wider sustainable agricultural innovation. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Figure 1

Review

Jump to: Research

45 pages, 1407 KB

Open AccessReview

Mining Waste as a Resource in Construction: Applications, Benefits, and Challenges

by Chathurika Dassanayake, Nuha S. Mashaan and Daniel Oguntayo

Sustainability 2026, 18(3), 1361; https://doi.org/10.3390/su18031361 - 29 Jan 2026

Viewed by 1077

Abstract

Mining activities generate vast quantities of waste each year, including mine tailings, bauxite residue, waste rock, and various metallurgical slags. Although these materials have traditionally been regarded as environmental liabilities, many possess physical and chemical properties that make them promising candidates for use in construction. This review synthesizes recent research on the utilization of major mining waste streams, with particular emphasis on pavement applications and other construction materials. The findings indicate that bauxite residue exhibits both pozzolanic and filler characteristics, demonstrating potential in asphalt mastics, asphalt mixtures, and other construction products. Nonetheless, its widespread adoption is constrained by issues such as high alkalinity, leaching risks, and concerns related to naturally occurring radioactivity. Mine tailings can be a substitute for fine aggregates and cement in a range of mixtures, though challenges, including pronounced material variability and environmental risks, persist. Waste rock offers favorable geotechnical properties for use in road bases and embankments, while metallurgical slags (e.g., copper, nickel, and lithium slags) provide functional pozzolanic activity and suitable aggregate qualities. Across all waste types, their incorporation into construction materials can conserve natural resources, reduce material costs, and support circular-economy and low-carbon development objectives. However, progress remains contingent upon advancements in material standards, pretreatment technologies, environmental protection measures, and large-scale field validation. Overall, this review underscores both the significant potential and the practical challenges associated with transforming mining waste into valuable and sustainable construction resources. Full article

(This article belongs to the Special Issue Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition)

► Show Figures

Journal Menu

Journal Browser

Research Progress and Evaluation Challenges of By-Product and Waste Valorization, 2nd Edition

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (7 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI