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Valorization of Industrial and Agro Waste

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A special issue of Clean Technologies (ISSN 2571-8797).

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 14619

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Dr. Rosa Taurino

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Department of Industrial Engineering, University of Florence, Via di Santa Marta 3, 50139 Firenze, Italy
Interests: valorization of waste; industrial waste, and agro-waste in new materials for the green-building sector (ceramic materials and composite materials); preparation and characterization of biocomposites from renewable sources; development of hybrid materials via the sol–gel process

Special Issue Information

Dear colleagues,

With the rapid growth of the world’s population and advances in processing technology, the generation of waste has increased, amounting to 4 billion tons. This vast amount of waste is expected to increase by the year 2025. This vast amount of waste, if not managed properly, can cause large environmental impacts, including climate-harming emissions through illegal dumping. With this perspective, the productive use of waste represents a possible way to reduce some of the problems associated with their management, reducing the use of natural resources and, in some cases, resulting in the production of environmentally friendly products.

This Special Issue aims to compile the latest research on the broad topic of waste valorization by including conversion methods, technological–social–environmental–economy analyses, and scaling-up strategies. We welcome full-length articles and short or comprehensive review papers. Topics of interest for this Special Issue include, but are not limited to, the following:

Waste to value-added chemicals (e.g., bulk and fine chemicals, as well as platform chemicals);
Waste to materials (e.g., biopolymers, bioplastics, new composite materials, materials for the building sector, and bionanomaterials);
Process optimization and technologies used in waste valorization (e.g., pyrolysis, gasification, transesterification reactions, pretreatment, hydrolysis, fermentation, and downstream processes);
Technological–social–environmental–economy analyses of waste-based materials (e.g., TEA, LCA, and supply chain logistics).

Dr. Rosa Taurino
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. Clean Technologies is an international peer-reviewed open access quarterly 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 1600 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

agricultural waste
industrial waste
biomass
waste valorization
resources
sustainable development
circular economy

Published Papers (7 papers)

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Research

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17 pages, 5415 KiB

Open AccessArticle

Reinforcement Fiber Production from Wheat Straw for Wastepaper-Based Packaging Using Steam Refining with Sodium Carbonate

by Sebastian Hagel and Fokko Schütt

Clean Technol. 2024, 6(1), 322-338; https://doi.org/10.3390/cleantechnol6010016 - 05 Mar 2024

Viewed by 1083

Abstract

Locally sourced agricultural residues are a promising feedstock for the production of reinforcement fibers for wastepaper-based packaging papers. An eco-friendly high yield process to generate fibers from wheat straw using high pressure steam and sodium carbonate is presented. The wheat straw was impregnated with up to 16% of sodium carbonate and steam treated for 10 min at temperatures from 148 °C to 203 °C. The pulps were characterized concerning their chemical composition and test sheets with 100% straw fibers and with 15% and 30% straw fibers blended with recycled pulp were prepared. Fiber yields ranged from 70% to 45%, wherein more severe treatment conditions contributed to increased paper strength but lower yields. At comparable fiber yields, treatments featuring a higher chemical input, coupled with lower treatment temperatures, resulted in improved paper strength. By blending recycled pulp with up to 30% of straw fibers with a beating degree of roughly 45 °SR, the burst, compression and tensile strength was enhanced by up to 66%, 74% and 59%, respectively. As the enhancement effect decreases with a high steam treatment intensity and a high proportion of wheat straw, a moderate treatment and limited use of wheat straw may be the best choice. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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15 pages, 2281 KiB

Open AccessArticle

Exploration of In Vitro Voltage Production by a Consortium of Chemolithotrophic Microorganisms Using Galena (PbS) as a Sulphur Source

by Susana Citlaly Gaucin Gutiérrez, Juan Antonio Rojas-Contreras, David Enrique Zazueta-Álvarez, Efren Delgado, Perla Guadalupe Vázquez Ortega, Hiram Medrano Roldán and Damián Reyes Jáquez

Clean Technol. 2024, 6(1), 62-76; https://doi.org/10.3390/cleantechnol6010005 - 03 Jan 2024

Viewed by 1583

Abstract

Sulphur plays a fundamental role in the biological processes of chemolithotrophic microorganisms. Due to the redox characteristics of sulphur, microorganisms use it for metabolic processes. Such is the case of the dissimilatory processes in the anaerobic respiration of reducing microorganisms. The production of electrical energy from the metabolism of native microorganisms using sulphur as substrate from inorganic mineral sources in the form of Galena (PbS) was achieved using MR mineral medium with 15% (w/v) of PbS mineral concentrate. At 400 h of growth, the highest voltage produced in an experimental unit under anaerobic conditions was 644 mV. The inoculum was composed of microorganisms with spiral morphology, and at the final stages of energy production, the only microorganism identified was Bacillus clausii. This microorganism has not been reported in bioelectrochemical systems, but it has been reported to be present in corrosive environments and reducing anoxic environments. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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13 pages, 3048 KiB

Open AccessArticle

Delipidation of Chicken Feathers by Lipolytic Bacillus Species Isolated from River-Borne Sediments

by Tariro Shiri, Nonso E. Nnolim and Uchechukwu U. Nwodo

Clean Technol. 2023, 5(4), 1235-1247; https://doi.org/10.3390/cleantechnol5040062 - 18 Oct 2023

Viewed by 1461

Abstract

Though the keratin content of chicken feathers is being explored for many potential uses, the crude lipid content of the biomass significantly hinders the valorization processes. Therefore, this study explored the potential of bacteria isolated from sediment for lipolytic properties. Sediment-associated strains were evaluated for lipolytic activity on tween 80–peptone agar. The best lipolytic bacterium was used to break down the lipid content of chicken feathers. The results showed that out of six bacterial strains with variable lipolytic activity, strain TTs1 showed the largest zone of precipitate around the colony, which is why it was selected and identified as Bacillus sp. TTs1. The maximum lipase production of 1530.5 U/mL by strain TTs1 was achieved at 96 h post-fermentation, with optimal process conditions of initial pH (10), incubation temperature (45 °C), agitation speed (140 rpm), inoculum size (2% v/v) and tween 80 (10% v/v). The total free fatty acid (0.58%) was liberated from chicken feathers at a concentration of 6% (w/v). Crude fat extraction from both untreated and TTs1-pretreated chicken feathers showed fat contents of 2.1 ± 0.42% and 0.92 ± 0.13%, respectively. The findings of this study highlight the biotechnological relevance of strain TTs1 in lipase production and the sustainable delipidation of lipid-rich bioresources. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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16 pages, 10268 KiB

Open AccessArticle

Extraction and Characterization of Cellulose Obtained from Banana Plant Pseudostem

by Rosa E. A. Nascimento, Mónica Carvalheira, João G. Crespo and Luísa A. Neves

Clean Technol. 2023, 5(3), 1028-1043; https://doi.org/10.3390/cleantechnol5030052 - 29 Aug 2023

Viewed by 3105

Abstract

Each year, the amount of residue generated from food production increases, caused by the continuous population growth. Banana is one of the most consumed fruits in the world, with an annual production of 116.78 million tonnes. However, just 12 wt% of the plant, corresponding to the bunch, is effectively used. After the bunch is harvested, the rest of the plant is disposed of as residue, the pseudostem (PS) being the main constituent. Aiming to give an added-value application to the PS, this work is focused on the extraction of cellulose from this waste. For this, three different fractions of PS particles—a non-classified fraction (milled but without sieving), a fine fraction (≤180 μm), and a coarse fraction (≥2000 μm)—and three extraction methods—alkaline-acid hydrolysis, enzymatic hydrolysis, and TEMPO oxidation—were studied to determine the most promising method for the cellulose extraction from the PS. The alkaline-acid hydrolysis samples presented a higher number of amorphous compounds, resulting in lower crystallinity (13.50% for the non-classified fraction). The TEMPO-oxidation process, despite allowing the highest cellulose extraction yield (25.25 ± 0.08% on a dried basis), resulted in samples with lower thermal stability (up to 200 °C). The most promising extraction method was enzymatic, allowing the extraction of 14.58 ± 0.30% of cellulose (dried basis) and obtaining extracts with the highest crystallinity (68.98% for the non-classified fraction) and thermal stability (until 250 °C). Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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21 pages, 4555 KiB

Open AccessArticle

Torrefaction of Pine Using a Pilot-Scale Rotary Reactor: Experimentation, Kinetics, and Process Simulation Using Aspen Plus™

by Suchandra Hazra, Prithvi Morampudi, John C. Prindle, Dhan Lord B. Fortela, Rafael Hernandez, Mark E. Zappi and Prashanth Buchireddy

Clean Technol. 2023, 5(2), 675-695; https://doi.org/10.3390/cleantechnol5020034 - 17 May 2023

Cited by 1 | Viewed by 2090

Abstract

Biomass is an excellent sustainable carbon neutral energy source, however its use as a coal/petroleum coke substitute in thermal applications poses several challenges. Several inherent properties of biomass including higher heating value (HHV), bulk density, and its hydrophilic and fibrous nature, all contribute to challenges for it to be used as a solid fuel. Torrefaction or mild pyrolysis is a well-accepted thermal pretreatment technology that solves most of the above-mentioned challenges and results in a product with superior coal-like properties. Torrefaction involves the heating of biomass to moderate temperatures typically between 200 °C and 300 °C in a non-oxidizing atmosphere. This study focused on evaluating the influence of torrefaction operating temperature (204–304 °C) and residence time (10–40 min) on properties of pine. Tests were performed on a continuous 0.3 ton/day indirectly heated rotary reactor. The influence of torrefaction operational conditions on pine was evaluated in terms of the composition of torrefied solids, mass yield, energy yield, and HHV using a simulated model developed in Aspen Plus™ software. A kinetic model was established based on the experimental data generated. An increase in torrefaction severity (increasing temperature and residence time) resulted in an increase in carbon content, accompanied with a decrease in oxygen and hydrogen. Results from the simulated model suggest that the solid and energy yields decreased with an increase in temperature and residence time. Solid yield varied from 80% at 204 °C to 68% at 304 °C, and energy yield varied from 99% at 204 °C to 70% at 304 °C, respectively. On the other hand, HHV improved from 22.8 to 25.1 MJ/kg with an increase in temperature at 20 min residence time. Over the range of 10 to 40 min residence time at 260 °C, solid and energy yields varied from 77% to 59% and 79% to 63%, respectively; however the HHV increased by only 3%. Solid yield, energy yield, and HHV simulated data were within the 5% error margin when compared to the experimental data. Validation of the simulation parameters was achieved by the conformance of the experimental and simulation data obtained under the same testing conditions. These simulated parameters can be utilized to study other operating conditions fundamental for the commercialization of these processes. Desirable torrefaction temperature to achieve the highest solid fuel yield can be determined using the energy yield and mass loss data. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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Review

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23 pages, 1022 KiB

Open AccessReview

Superhydrophobic Materials from Waste: Innovative Approach

by Maria Cannio, Dino Norberto Boccaccini, Stefano Caporali and Rosa Taurino

Clean Technol. 2024, 6(1), 299-321; https://doi.org/10.3390/cleantechnol6010015 - 04 Mar 2024

Viewed by 1559

Abstract

Superhydrophobic materials, known for their exceptional water-repellent properties, have found widespread applications in diverse fields such as self-cleaning surfaces, anti-icing coatings, and water-resistant textiles. In recent years, researchers have explored a sustainable approach by repurposing waste materials to create superhydrophobic surfaces. This eco-friendly approach not only reduces environmental impact but also aligns with circular economy principles, contributing to a more sustainable future. Creating superhydrophobic materials from waste involves a combination of surface modification techniques and hierarchical structuring, with rigorous characterization to ensure the desired properties. These materials showcase their potential in various industries, opening doors to more environmentally friendly technologies. This review delves into the concept of superhydrophobic materials derived from waste and the methods used for their synthesis. It begins by defining superhydrophobicity and highlighting its unique characteristics. It emphasizes the pivotal role played by superhydrophobic materials across industries. The review then explores waste materials’ untapped potential, discussing the advantages of harnessing waste for superhydrophobic material development. Concrete examples of promising waste materials are provided, including agricultural residues and industrial byproducts. The review outlines five key sections that will be further developed to offer a comprehensive understanding of this innovative and sustainable approach to superhydrophobic materials. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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40 pages, 2389 KiB

Open AccessReview

Poly(lactic acid) and Its Blends for Packaging Application: A Review

by Stefano De Luca, Daniel Milanese, Duccio Gallichi-Nottiani, Antonella Cavazza and Corrado Sciancalepore

Clean Technol. 2023, 5(4), 1304-1343; https://doi.org/10.3390/cleantechnol5040066 - 10 Nov 2023

Cited by 2 | Viewed by 2926

Abstract

Biopolymers obtained from renewable resources are an interesting alternative to conventional polymers obtained from fossil resources, as they are sustainable and environmentally friendly. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester produced from 100% renewable plant resources and plays a key role in the biopolymer market, and is experiencing ever-increasing use worldwide. Unfortunately, this biopolymer has some usage limitations when compared with traditional polymers; therefore, blending it with other biopolymers, such as poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), poly(butylene adipate-co-butylene terephthalate) (PBAT) and different poly(hydroxyalkanoates) (PHA), is considered an interesting method to improve it significantly, customize its properties and extend the range of its applications. The following review highlights, in its first part, the physico-chemical and mechanical properties of PLA in comparison to the other biopolymers listed above, highlighting the various drawbacks of PLA. The second part of the review deals with recent developments, results, and perspectives in the field of PLA-based blends. Full article

(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)

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