Advances and Innovations in Waste Management

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Clean Technologies cleantechnol	5.9	9.4	2019	20.9 Days	CHF 1800	Submit
Polymers polymers	5.8	11.0	2009	13.4 Days	CHF 2700	Submit
Recycling recycling	5.2	7.5	2016	19.4 Days	CHF 1800	Submit
Resources resources	4.3	7.3	2012	20.3 Days	CHF 1800	Submit
Sustainability sustainability	4.1	8.9	2009	16.9 Days	CHF 2400	Submit

26 pages, 5786 KB

Open AccessArticle

Sustainable Fertilization with Iron-Enriched Montmorillonite and Sanitary Sludge Enhances Germination and Growth of Zea mays L.

by Wagner Alves Carvalho, Alessandro Lamarca Urzedo, Natalí Romero, Luciana Regaldo, Leticia Ferreira Lima Machado and Ana Maria Gagneten

Resources 2026, 15(5), 67; https://doi.org/10.3390/resources15050067 - 12 May 2026

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Abstract

Sustainable fertilization strategies are required to reduce dependence on synthetic inputs, enhance waste recycling, and improve agricultural resilience under climate change. This study evaluates the effects of wastewater-derived sludge, particularly when modified with Fe-montmorillonite, on phosphorus availability and early development of Zea mays [...] Read more.

Sustainable fertilization strategies are required to reduce dependence on synthetic inputs, enhance waste recycling, and improve agricultural resilience under climate change. This study evaluates the effects of wastewater-derived sludge, particularly when modified with Fe-montmorillonite, on phosphorus availability and early development of Zea mays. Methods: Germination and early growth of Zea mays were assessed under four treatments: (i) untreated soil (Control); (ii) soil amended with sludge from the Cardeal Wastewater Treatment Plant (SC); (iii) soil amended with Fe-montmorillonite-modified sludge (TechPhos, ST); and (iv) soil amended with a commercial phosphorus salt (PS). Soil characterization was conducted using XRF, XRD, and FTIR. Plant responses were evaluated through laboratory (5 days) and pot (22 days) experiments. Results: ST showed the highest performance, with a germination index of 171.7 and improved biomass, leaf development, and chlorophyll content compared to Control and SC. ST also performed similarly to or better than the commercial fertilizer (PS), indicating high phosphorus efficiency. Conclusions: The integration of nanostructured modified montmorillonite with wastewater-derived sludge represents a promising alternative phosphorus source for early maize development. Its application supports waste valorization and circular economy approaches while contributing to improved soil fertility and more sustainable nutrient management under climate change scenarios. Full article

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18 pages, 1351 KB

Open AccessArticle

FT-NIR-Based Sludge Moisture Prediction: Spectral Variability and Implications for On-Site Application in WWTPs

by Irfan Basturk, Ibrahim Sani Ozdemir, Hande Gulcan, Selda Murat Hocaoglu, Recep Partal, Burak Bozcelik, Charuka Saamantha Meegoda, Harsha Ratnaweera and Zakhar Maletskyi

Clean Technol. 2026, 8(3), 74; https://doi.org/10.3390/cleantechnol8030074 - 9 May 2026

Cited by 1 | Viewed by 1032

Abstract

Accurate and rapid determination of moisture content in waste sludge is essential for optimizing dewatering processes, reducing disposal costs, and minimizing environmental impact. This study investigates the use of Fourier Transform Near-Infrared (FT-NIR) spectroscopy combined with Partial Least Squares Regression (PLS-R) for predicting [...] Read more.

Accurate and rapid determination of moisture content in waste sludge is essential for optimizing dewatering processes, reducing disposal costs, and minimizing environmental impact. This study investigates the use of Fourier Transform Near-Infrared (FT-NIR) spectroscopy combined with Partial Least Squares Regression (PLS-R) for predicting the moisture content of dewatered sludge. A total of 96 sludge samples, with dry matter contents ranging from 12.4% to 24.6%, were collected from two treatment plants. FT-NIR spectra were acquired over the 800–2500 nm range, and chemometric models were developed to correlate spectral information with gravimetrically determined moisture content. The optimized PLS-R model demonstrated strong predictive performance, achieving a cross-validated coefficient of determination (R²_CV) of 0.87, a root mean square error of cross-validation (RMSECV) of 0.92%, and a residual predictive deviation (RPD) of 2.73. Independent test set validation confirmed the robustness of the model (R²_Test = 0.88, RMSEP = 0.88%, RPD = 2.92), supported by strong calibration results (R²_CT = 0.95, RMSEE = 0.60%, RPD = 4.46). Principal component analysis indicated that spectral variability observed in sludge samples was primarily associated with wastewater treatment plant (WWTP)-specific characteristics, reflecting moisture–organic matter interactions. These results demonstrate that FT-NIR spectroscopy is a promising tool for sludge moisture prediction. Full article

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16 pages, 1311 KB

Open AccessArticle

Eco-Friendly Recovery of Biocompounds from Agro-Industrial By-Products Using Non-Thermal Processing

by Maria N. Berradre, Cristina Arroqui, Idoya Fernández-Pan, María José Beriain, Francisco C. Ibañez and Paloma Vírseda

Clean Technol. 2026, 8(3), 64; https://doi.org/10.3390/cleantechnol8030064 - 1 May 2026

Viewed by 748

Abstract

The valorization of agro-industrial by-products through sustainable extraction of bio-compounds is a key challenge within circular economy and clean-processing frameworks, as large volumes of tomato and artichoke residues are generated by the food industry. This study evaluated the impact of non-thermal technologies on [...] Read more.

The valorization of agro-industrial by-products through sustainable extraction of bio-compounds is a key challenge within circular economy and clean-processing frameworks, as large volumes of tomato and artichoke residues are generated by the food industry. This study evaluated the impact of non-thermal technologies on the recovery of biocompounds from tomato peels and blanched artichoke bracts using single green solvents instead of solvent mixtures. Ultrasound-assisted extraction (sonication), high-pressure processing (pressurization), and dual processing (pressurization + sonication) were compared with conventional extraction. Ethanol was used for lycopene extraction, while water was employed for inulin-type fructan recovery. Lycopene, total phenolic content, antioxidant activity, and inulin-type fructans were quantified. Non-thermal treatments significantly influenced extraction yields (p < 0.05). The dual processing provided the highest lycopene and inulin-type fructan contents (1440.09 ± 0.71 µg/g DW and 5.17 ± 0.51 g/100 g DW, respectively) and enhanced antioxidant activity in tomato peels and blanched artichoke bracts (25.50 ± 0.20% and 66.11 ± 2.03%), and phenolic co-extraction (1783.2 ± 215.3 μg GAE/g DW and 27.68 ± 1.29 mg GAE/g DW) outperformed individual technologies and conventional extraction. Compared with the conventional process, dual processing improved the extraction yields of lycopene (20.60 ± 0.44%) and inulin (26.40 ± 13.95%). The findings prove that non-thermal processes, particularly when combined, intensify mass transfer and enable efficient extraction using green solvents, offering a sustainable strategy for recovering bioactive compounds from tomato and artichoke by-products. Full article

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20 pages, 3033 KB

Open AccessArticle

Multi-Criteria Decision Analysis for Mechanical Recyclability Assessment of Different Types of PET Packaging Waste

by Giusy Santomasi, Francesco Todaro, Michele Notarnicola and Eggo Ulphard Thoden van Velzen

Polymers 2026, 18(9), 1063; https://doi.org/10.3390/polym18091063 - 28 Apr 2026

Viewed by 898

Abstract

The management of plastic packaging waste needs to be optimized to improve recycling rates. In this article, fourteen categories of non-bottle polyethylene terephthalate (PET) packages were mechanically recycled at laboratory bench scale; the generated data were assessed using a multi-criteria decision analysis (MCDA) [...] Read more.

The management of plastic packaging waste needs to be optimized to improve recycling rates. In this article, fourteen categories of non-bottle polyethylene terephthalate (PET) packages were mechanically recycled at laboratory bench scale; the generated data were assessed using a multi-criteria decision analysis (MCDA) approach to identify the categories most suited for the mechanical recycling process from social, technical and legislative viewpoints. Recycling yields varied between 75% and 92% across the 14 categories. The intrinsic viscosity (IV) values of the produced recycled PET (rPET) corresponded to molecular weights ranging from 28,000 to 35,000 g/mol. The MCDA recyclability assessment showed that 7 of the 14 categories (accounting for 72% of the sorted products by mass flow) are often composed of multiple, inseparable materials, resulting in the lowest-quality rPET. Furthermore, only 4 categories (approximately 28% of the categories) were found suitable for closed-loop mechanical recycling. The stakeholders involved in the PET packaging value chain could use these results to support decision-making and the development of a well-organized framework to valorize even the most complex types of plastic waste. Full article

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16 pages, 3397 KB

Open AccessArticle

Biomass-Derived Carbon–Silica Hybrid Biochar for Nano- and Microplastic Adsorption

by Weimin Gao, Qiyang Ling, Dantong Zhu and Xiangju Cheng

Sustainability 2026, 18(8), 3721; https://doi.org/10.3390/su18083721 - 9 Apr 2026

Cited by 1 | Viewed by 853

Abstract

Nano- and microplastic contamination poses a growing challenge to aquatic environments, driving the need for efficient and sustainable removal technologies. In this study, carbon–silica hybrid nanoparticles (CSNPs) were synthesized from rice husk-derived black liquor via controlled lignin–silica self-assembly followed by thermal carbonization, providing [...] Read more.

Nano- and microplastic contamination poses a growing challenge to aquatic environments, driving the need for efficient and sustainable removal technologies. In this study, carbon–silica hybrid nanoparticles (CSNPs) were synthesized from rice husk-derived black liquor via controlled lignin–silica self-assembly followed by thermal carbonization, providing a waste-recycling biorefinery route for value-added material production. Structural characterizations revealed that carbonization generates a hierarchically porous carbon–silica hybrid with enhanced surface area. The CSNPs exhibited rapid and size-dependent adsorption toward nano- and microplastics (200–1000 nm), with optimal performance observed for 500 nm particles. Microscopic observations further demonstrated a size-adaptive capture mechanism, involving pore filling and surface adsorption for nanoplastics and aggregate-assisted encapsulation for larger microplastics. This study highlights CSNPs as low-cost and effective adsorbents for broad-spectrum plastic removal while offering a sustainable pathway for the high-value utilization of black liquor and rice husk biomass in water purification applications. Full article

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16 pages, 4470 KB

Open AccessArticle

Innovative Protocol for Catalytic Hydrodehalogenation of Chlorobenzene and Bromobenzene for WEEE Cycle Closure

by Bianca Maria Falco, Milvia Elena Di Clemente, Francesco Todaro, Maria Michela Dell’Anna, Paolo Francesco Garofoli and Michele Notarnicola

Sustainability 2026, 18(5), 2485; https://doi.org/10.3390/su18052485 - 4 Mar 2026

Viewed by 560

Abstract

Pyrolysis of plastic from waste electrical and electronic equipment (WEEE) is a promising method for producing value-added chemicals. However, flame retardants in WEEE can cause halogen contamination in pyrolysis oil, reducing its value. This work aims to develop an innovative catalytic hydrodehalogenation (CHD) [...] Read more.

Pyrolysis of plastic from waste electrical and electronic equipment (WEEE) is a promising method for producing value-added chemicals. However, flame retardants in WEEE can cause halogen contamination in pyrolysis oil, reducing its value. This work aims to develop an innovative catalytic hydrodehalogenation (CHD) protocol for the removal of chlorobenzene and bromobenzene. Iron sulphate heptahydrate (FeSO₄·7H₂O) and nickel ammonium sulphate hexahydrate ((NH₄)₂Ni(SO₄)₂·6H₂O) were used as catalysts, while sodium borohydride (NaBH₄) acted as a hydrogen donor for iron reduction. The novelty of the process lies in the generation of nano zero-valent iron (nZVI) that takes place within the CHD reactor (in situ) without the addition of strong acids. Various experimental set-ups were investigated to optimise the key process parameters (e.g., reagent concentrations). The optimal conditions—obtained in the autoclave at 30 °C with a 1:1 molar ratio of chlorobenzene to catalyst, omission of nickel salt, and 5 mmol of NaBH₄—resulted in a 75% reduction in chlorobenzene and complete removal of bromobenzene. The results confirm the effectiveness of the proposed protocol for the dehalogenation of chlorobenzene and bromobenzene, which can facilitate the valorization of pyrolysis oils derived from plastic waste, contributing to the closure of the WEEE cycle (the widest and fastest-growing source of global waste with significant environmental, social and economic impacts). Full article

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21 pages, 7102 KB

Open AccessArticle

Natural Deep Eutectic Solvent-Assisted Hydrothermal Carbonization of Corn Stover for Producing Lignin-Rich Solid Fuel and Sugar-Rich Intermediates

by Mohammad Tarikuzzaman, Shaurav Alam, Muhammad Aamir Iqbal, Md Reazul Islam, Zannatul Ferdous Tulona and Joan G. Lynam

Clean Technol. 2026, 8(1), 25; https://doi.org/10.3390/cleantechnol8010025 - 14 Feb 2026

Cited by 1 | Viewed by 1482

Abstract

The sustainable conversion of agricultural waste biomass, particularly crop residues such as corn stover, into high-value products is vital for reducing their open-field burning and mitigating environmental hazards. The hydrothermal carbonization (HTC) process integrated with natural deep eutectic solvents (NADES) presents an alternative [...] Read more.

The sustainable conversion of agricultural waste biomass, particularly crop residues such as corn stover, into high-value products is vital for reducing their open-field burning and mitigating environmental hazards. The hydrothermal carbonization (HTC) process integrated with natural deep eutectic solvents (NADES) presents an alternative approach for valorizing biomass into lignin-rich solid fuels and fermentable sugars for bioethanol production. In this study, corn stover was subjected to HTC using deionized (DI) water, a xylose-based NADES (ChCl:Xy:W), and an oxalic acid-based NADES (ChCl:OA:W) in a 150–300 °C temperature range to optimize both solid fuel and sugar stream yields. Characterization, including fiber analysis, SEM, FTIR, EDS, and bomb calorimetry, was conducted to evaluate structural, compositional, and energetic transformations. The results explored the HTC process, restructuring the biomass, promoting extensive hemicellulose solubilization and cellulose depolymerization, as well as substantially enriching lignin and polymerized compounds with increasing temperature. In addition, the DI water at 300 °C generated a lignin-rich residue, the Xy-based NADES effectively removed ash and extractives, and the OA-based NADES produced the most carbon-dense hydrochar with the highest calorific value. Collectively, these findings demonstrate that solvent-assisted HTC may be employed as a possible strategy for the valorization of agricultural residues into high-energy solid fuels. Full article

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18 pages, 5981 KB

Open AccessArticle

Material Performance and Processing Behavior of Polyolefin Waste in Mechanical Recycling

by Yamila V. Vazquez, Cristina Pavon, Juan Vicente Miguel Guillem, Juan López-Martínez and María Dolores Samper

Recycling 2026, 11(2), 26; https://doi.org/10.3390/recycling11020026 - 1 Feb 2026

Cited by 1 | Viewed by 1497

Abstract

This study investigates the processability and performance limits of high-density polyethylene (HDPE) recovered from mixed polyolefin waste under realistic mechanical recycling conditions. The waste stream was processed by extrusion and injection molding, with parameters actively adapted. ATR-FTIR and DSC analysis confirmed HDPE as [...] Read more.

This study investigates the processability and performance limits of high-density polyethylene (HDPE) recovered from mixed polyolefin waste under realistic mechanical recycling conditions. The waste stream was processed by extrusion and injection molding, with parameters actively adapted. ATR-FTIR and DSC analysis confirmed HDPE as the matrix, contaminated with minor fractions of polypropylene (PP), PET, and polyurethane (PU). The reprocessed material exhibited a single melting peak at 132 °C and a melt flow rate (MFR) of 9.9 ± 0.6 g 10 min⁻¹, indicative of moderate degradation. Mechanical testing revealed reduced tensile strength and elongation at break compared to virgin HDPE, indicating compositional heterogeneity and poor interfacial adhesion. Field emission scanning electron microscopy (FESEM) revealed dispersed inclusions and microvoids acting as stress concentrators, consistent with reduced ductility. Crucially, progressive reduction of back pressure during processing optimization was essential for stabilizing melt flow and minimizing shear-induced degradation. This adjustment enabled consistent mold filling despite the material’s variability. The results demonstrate that mixed HDPE waste can be successfully valorized for non-structural applications such as plastic lumber or pallets, providing a sustainable pathway for recycling heterogeneous streams without costly pre-treatment or compatibilization. Full article

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16 pages, 11595 KB

Open AccessArticle

Synergistic Effects of Steel Fiber and Rubber Powder on the Physico-Mechanical Properties of UHPC

by Changqing Luo, Hao Wang, Dongbo Cai, Anni Wang, Lianzhen Zhang, Deming Wang, Chao Wang, Degao Kong, Sining Huang and Chaohui Xu

Sustainability 2026, 18(2), 846; https://doi.org/10.3390/su18020846 - 14 Jan 2026

Viewed by 474

Abstract

This study investigates the synergistic effects of steel fibers and waste rubber powder on the properties of ultra-high-performance concrete (UHPC) to advance its sustainable development. A comprehensive experimental program was conducted, incorporating three types of steel fibers (8 mm straight, and 14 mm [...] Read more.

This study investigates the synergistic effects of steel fibers and waste rubber powder on the properties of ultra-high-performance concrete (UHPC) to advance its sustainable development. A comprehensive experimental program was conducted, incorporating three types of steel fibers (8 mm straight, and 14 mm and 20 mm hook-end) at volumes up to 2.5%, and rubber powder as quartz sand replacement at levels from 5% to 30%. The flowability, compressive strength, splitting tensile strength, abrasion resistance, and chloride ion penetration resistance of the mixtures were evaluated. The results indicate that steel fiber reinforcement significantly enhances the mechanical and durability properties. Specifically, a 2.5% steel fiber content increased the compressive strength, splitting tensile strength, and abrasion resistance by 28.9%, 55.3%, and 72.4%, respectively. Conversely, the incorporation of rubber powder improved flowability (optimal at 10% replacement) and abrasion resistance (increased by 41.1% at 30% content) but at the expense of reduced mechanical strength and increased chloride ion permeability. The primary novelty of this work lies in systematically quantifying the trade-offs and synergistic interactions between a wide range of steel fiber geometries and high-volume rubber powder content, providing a practical basis for designing UHPC with balanced performance and enhanced sustainability. Full article

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23 pages, 699 KB

Open AccessArticle

Co-Treatment of Municipal Landfill Leachate in Sewage Treatment Plants: A Model Based on a Literature Review

by Julio Cesar Wasserman and Tácila Oliveira Pinto de Freitas

Resources 2026, 15(1), 13; https://doi.org/10.3390/resources15010013 - 7 Jan 2026

Cited by 1 | Viewed by 1682

Abstract

The management of landfill leachate remains a persistent environmental issue for municipalities globally. Although dedicated treatment in engineered landfills mitigates environmental contamination, it is often cost-prohibitive. Co-treatment of landfill leachates in sewage treatment plants has been broadly studied, but there are a lot [...] Read more.

The management of landfill leachate remains a persistent environmental issue for municipalities globally. Although dedicated treatment in engineered landfills mitigates environmental contamination, it is often cost-prohibitive. Co-treatment of landfill leachates in sewage treatment plants has been broadly studied, but there are a lot of issues associated with it. Sewage treatment plants apply physical, chemical, and biological processes, and the co-treatment of leachates—contaminated with metals, pesticides, emerging contaminants, and other toxic compounds—can impair the biological equilibrium of the system and compromise the quality of effluents and sludges. In the present research, the processes leading to the formation of landfill leachates and the processes that promote the removal of contaminants in sewage treatment plants were discussed. A theoretical, early screening level mixing model, incorporating removal rates and leachate concentrations from the literature, was employed to simulate effluent concentrations from a co-treatment process involving sequential decantation and an upflow anaerobic sludge blanket (UASB). Under a conservative worst-case scenario obtained from the literature, the model predicts that adsorption of contaminants onto the particulate phase enables removal of metals from the solution. However, considering the volumes of sludge involved, the predictions indicate that concentrations should be lower than naturally occurring in the sediments. It is proposed that continuous monitoring follow-up is a mandatory safeguard for any co-treatment operation. Full article

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17 pages, 3258 KB

Open AccessArticle

Sustainable Cellulose- and Pectin-Rich Triboelectric Nanogenerator for Mechanical Energy Harvesting and Self-Powered Humidity Sensing

by Seongwan Kim, Farhan Akhtar, Shahzad Iqbal, Muhammad Muqeet Rehman and Woo Young Kim

Polymers 2025, 17(23), 3130; https://doi.org/10.3390/polym17233130 - 25 Nov 2025

Cited by 4 | Viewed by 1510

Abstract

This study develops a high-performance triboelectric nanogenerator (TENG) through Citrullus lanatus rind powder (CLP) which originates from watermelon waste to generate sustainable power and detect humidity. The SEM and FTIR results showed that CLP contains a natural porous structure and multiple polar functional [...] Read more.

This study develops a high-performance triboelectric nanogenerator (TENG) through Citrullus lanatus rind powder (CLP) which originates from watermelon waste to generate sustainable power and detect humidity. The SEM and FTIR results showed that CLP contains a natural porous structure and multiple polar functional groups which improve both the charge transfer and retention capabilities. The CLP-TENG device operated in vertical contact–separation mode with PTFE as the counter layer to generate a 255 V open-circuit voltage and 30 µA short-circuit current and 35 µW peak power output at 4 Hz and 20 MΩ load. The device successfully charged a 4.7 µF capacitor to 5 V during a 80 s period and operated low-power electronic devices to prove its ability as a sustainable power source. The device output increased with increasing operating frequency while showing operation stability throughout more than 1000 cycles and seven days of continuous operation. The device demonstrated a strong humidity detection ability through its voltage response which decreased from 250 V to 120 V when the relative humidity rose from 30% to 90%. The research proves that agricultural waste can be transformed into environmentally friendly materials which perform well in green energy systems and environmental monitoring applications. Full article

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22 pages, 6082 KB

Open AccessArticle

Activated Desulfurized Rubber Powder/SBS/SEBS Composite-Modified Asphalt: Performance and Synergistic Modification Mechanism

by Qidong Su, Songqiao Yang, Wenjing Liu, Mingming Zhang, Aoxue Li and Dongwei Cao

Polymers 2025, 17(23), 3113; https://doi.org/10.3390/polym17233113 - 24 Nov 2025

Cited by 2 | Viewed by 1203

Abstract

Due to the poor comprehensive performance of traditional rubber powder-modified asphalt (RA) and issues like easy segregation in rubber powder/Styrene–Butadiene–Styrene (SBS) composite-modified asphalt, the application of RA in high-grade highways is limited. This study combined SEBS (Styrene–Ethylene–Butylene–Styrene) and SBS to form SEBS/SBS (SE-S) [...] Read more.

Due to the poor comprehensive performance of traditional rubber powder-modified asphalt (RA) and issues like easy segregation in rubber powder/Styrene–Butadiene–Styrene (SBS) composite-modified asphalt, the application of RA in high-grade highways is limited. This study combined SEBS (Styrene–Ethylene–Butylene–Styrene) and SBS to form SEBS/SBS (SE-S) and investigated the effect of the SE-S system on asphalt performance. The activated desulfurized rubber powder (ARP) was prepared via mechanical thermal oxidation and used to produce ARP/SE-S composite-modified asphalt (ASSA) combined with SE-S. The performance and modification mechanism of ASSA were evaluated through conventional, rheological, and microstructural tests. The results showed that SEBS improved storage stability more effectively than SBS. With SEBS:SBS = 0.4:0.6 and a SE-S content of 2–4%, the modified asphalt exhibited better overall performance. The synergy of ARP and SE-S enhances both low-temperature crack resistance and high-temperature deformation resistance, endowing ASSA with excellent viscoelastic rheological properties. The modification mechanism of ASSA was primarily physical and the changes in chemical bonds were mainly caused by decrosslinking of the rubber powder during ARP preparation. SE-S and ARP fully swelled and crosslinked in the asphalt, exhibiting excellent compatibility and endowing the ASSA with superior stability and performance. Full article

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21 pages, 1746 KB

Open AccessReview

Carbon Recovery from Wastewater Feedstocks: Synthesis of Polyhydroxyalkanoates for Target Applications

by Mario I. Sepúlveda, Michael Seeger and Gladys Vidal

Resources 2025, 14(10), 156; https://doi.org/10.3390/resources14100156 - 1 Oct 2025

Cited by 5 | Viewed by 2870

Abstract

Polyhydroxyalkanoate (PHA) bioplastics are produced from wastewater as a carbon recovery strategy. However, the tuneable characteristics of PHAs and wastewater biorefinery potential have not been comprehensively reviewed. The aim of this study is to review the main challenges and strategies for carbon recovery [...] Read more.

Polyhydroxyalkanoate (PHA) bioplastics are produced from wastewater as a carbon recovery strategy. However, the tuneable characteristics of PHAs and wastewater biorefinery potential have not been comprehensively reviewed. The aim of this study is to review the main challenges and strategies for carbon recovery from wastewater feedstocks via PHA production, assessing potential target biopolymer applications. Diverse PHA-accumulating prokaryotes metabolize organic pollutants present in wastewater through different metabolic pathways, determining the biopolymer characteristics. The synthesis of PHAs using mixed microbial cultures with wastewater feedstocks derived from municipal, agro-industrial, food processing, lignocellulosic biomass processing and biofuel production activities are described. Acidogenic fermentation of wastewater feedstocks and mixed microbial culture enrichment are key steps in order to enhance PHA productivity and determine biopolymer properties towards customized bioplastics for specific applications. Biorefinery of PHA copolymers and extracellular polysaccharides (EPSs), including alginate-like polysaccharides, are alternatives to enhance the value-chain of carbon recovery from wastewater. PHAs and EPSs exhibit a wide repertoire of applications with distinct safety control requirements; hence, coupling biopolymer production demonstrations with target applications is crucial to move towards full-scale applications. This study discusses the relationship between the metabolic basis of PHA synthesis and composition, wastewater type, and target applications, describing the potential to maximize carbon resource valorisation. Full article

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19 pages, 1981 KB

Open AccessArticle

Physicochemical Characterisation of Olive Mill Wastewaters Based on Extraction Methods and Filtration Levels

by Inês S. Afonso, Cristina Duarte, Maria João Afonso, António E. Ribeiro, Joana S. Amaral, Patrícia C. Sousa, Rui A. Lima and João E. Ribeiro

Clean Technol. 2025, 7(3), 73; https://doi.org/10.3390/cleantechnol7030073 - 1 Sep 2025

Cited by 5 | Viewed by 3479

Abstract

Olive mill wastewaters (OMWW) generated during olive oil extraction represent a significant environmental challenge due to their high organic matter content, acidic pH, phenolic content, and toxicity. Their composition varies widely depending on the extraction method and remains difficult to treat, particularly for [...] Read more.

Olive mill wastewaters (OMWW) generated during olive oil extraction represent a significant environmental challenge due to their high organic matter content, acidic pH, phenolic content, and toxicity. Their composition varies widely depending on the extraction method and remains difficult to treat, particularly for small-scale producers lacking access to complex infrastructure. This study evaluates the combined effect of the extraction system (traditional vs. three-phase continuous) and filtration level (single vs. double) on the physicochemical and biological properties of OMWW. The methodologies employed included the analysis of water content, density, fatty acid composition, acidity, pH, total solids, chemical and biochemical oxygen demand, and biodegradability. The results indicate that traditional systems consistently produced OMWW with higher organic matter and phenolic loads, while filtration moderately reduced antioxidant potential and acidity, especially in traditional systems. The use of simple, low-cost filtration materials proved effective in improving effluent clarity and could serve as a practical pre-treatment option. This approach offers an accessible strategy for small producers aiming to valorise OMWW or reduce environmental impact. However, the study was conducted at the laboratory scale, and the long-term behaviour of filtered OMWW under real operating conditions remains to be evaluated. Full article

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24 pages, 8697 KB

Open AccessArticle

Recycling of Marine Sediments in Cement-Based Materials by Stabilization/Solidification Treatment: Effect on the Mechanical and Microstructural Properties

by Claudio Moreno Cino, Andrea Petrella, Francesco Todaro and Michele Notarnicola

Recycling 2025, 10(5), 169; https://doi.org/10.3390/recycling10050169 - 1 Sep 2025

Cited by 2 | Viewed by 2246

Abstract

Port maintenance causes large quantities of dredged sediment throughout the world. The disposal of this material in authorised landfills is economically disadvantageous, as well as being at odds with a circular economy model with a reduced impact on the environment. The application of [...] Read more.

Port maintenance causes large quantities of dredged sediment throughout the world. The disposal of this material in authorised landfills is economically disadvantageous, as well as being at odds with a circular economy model with a reduced impact on the environment. The application of stabilization/solidification treatment to dredged marine sediments allows an improvement of their physical and mechanical properties, together with the production of cement-based materials that can be used for road construction, as well as for making blocks and bricks. In this study, an experimental laboratory investigation is carried out on two samples of sandy sediments collected from the Mola di Bari harbour (Southern Italy), to identify sustainable management options for recovering materials that will be dredged. To assess the influence on mortars made from sediments with variable organic matter content and seawater, these were characterised from a chemical–physical point of view before and after washing treatment and oxidative processes. The products of the Stabilization/Solidification (S/S) treatment were evaluated in terms of workability, flexural and compressive strengths, and, furthermore, a microstructural study was conducted using SEM-EDX and optical microscopy to analyse the internal structure of the materials. The mechanical performance evaluation clearly demonstrated organic matter’s negative impact on strength development, resulting in a 16% reduction. Pre-treatments, such as sediment washing, effectively improved the performance of treated sediments (e.g., 24% increase in compressive strength). This study aims to demonstrate the benefits of recycling marine sediments in cement-based materials, highlighting how this process can enhance circularity and sustainability while reducing the environmental impact of dredging activities. Full article

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27 pages, 2759 KB

Open AccessReview

A Review of Global Municipal Solid Waste Management and Valorization Pathways

by Sagar Kafle, Bhesh Kumar Karki, Manish Sakhakarmy and Sushil Adhikari

Recycling 2025, 10(3), 113; https://doi.org/10.3390/recycling10030113 - 6 Jun 2025

Cited by 26 | Viewed by 15616

Abstract

Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews [...] Read more.

Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews often focus narrowly on specific technologies or regional case studies, lacking a comprehensive analysis of global research trends. This study addresses this significant gap by conducting a large-scale trend analysis based on 15,646 relevant articles screened from 25,068 Scopus-indexed publications from 1904 to 2023 using title, abstract, and keyword analysis. Literature-based comparative assessments were conducted to critically evaluate the pathways through TEE (techno-economic and environmental), SWOT (strengths, weaknesses, opportunities, and threats), and PESTEL (political, economic, social, technological, environmental, and legal) frameworks. Since 1990, article publication has increased by about 10% annually, consistently concentrating on thermochemical conversion and, more recently, on sustainability and circular economy perspectives. Seven distinct pathways for MSW management were identified, with recycling and material recovery, followed by thermochemical conversion for high-calorific waste and biochemical conversion for high-organic waste, showing the most promise. The findings aim to help researchers understand MSW research trends and assist planners in identifying effective management and valorization strategies. Full article

(This article belongs to the Topic Advances and Innovations in Waste Management)

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