Waste Management
Centre of Competence
Publications
Synthesis of Cleavable Polyolefins via Ring-Opening Insertion Metathesis Polymerization (ROIMP) of Cyclopentene with Unsaturated Polyester Oligomers
Authors: Vajk Farkas; Ádám Erdélyi; Kristóf Varga; Dang Vu Hai; Momoko Ishii; Márton Nagyházi; Gábor Turczel; Pooja Dubey; László Trif; Ole Osterthun; Paul T. Anastas; Jürgen Klankermayer; János Moczó; Róbert Tuba
Published in: Macromolecules, 59, 515–523 (2026).
Summary: This study developed a synthesis route for polyolefins containing chemically cleavable ester or carbonate groups within their chains. Cyclopentene was copolymerised with unsaturated oligomers using ring-opening insertion metathesis polymerisation. Hydrolysis yielded lower-molecular-weight, hydroxyl-terminated oligomers, while subsequent hydrogenation produced materials containing saturated hydrocarbon chains. Scale-up was demonstrated for a selected system, contributing to the development of plastics designed for easier chemical cleavage.
DOI: 10.1021/acs.macromol.5c03036
Size-resolved and seasonal assessment of the undersized fraction of municipal solid waste: Resource potential and environmental risks
Authors: Róbert Kurdi; Eliza Molnár; Kinga M. Berta; Csilla Őze; Csaba Leitol; Janka Bobek-Nagy
Published in: Journal of Environmental Management, 400, 128749 (2026).
Summary: This study characterised stabilised undersized municipal solid waste from a Hungarian mechanical–biological treatment facility across seasons and particle-size classes. The 20–60 mm fractions contained substantial amounts of plastics and paper and exhibited calorific values of up to 22.7 MJ/kg. By contrast, fractions below 10 mm showed considerable metal enrichment, limiting their safe recovery options. The results highlight particle-size separation as an essential step in isolating resource-rich components and reducing environmental risks.
DOI: 10.1016/j.jenvman.2026.128749
Model structures and approaches for municipal solid waste prediction – A review
Authors: Róbert Fejes; Róbert Kurdi; Viktor Sebestyén
Published in: Resources, Conservation & Recycling Advances, 29, 200310 (2026).
Summary: Based on 78 selected studies, this review systematises models and data sources for predicting municipal solid waste quantities. It catalogues 36 AI-driven models and 455 proxy variables. The authors propose a recommendation framework that supports the selection of model structures according to the prediction task, number of observations and available variables. The work provides methodological guidance for data-driven planning and the development of waste management infrastructure.
DOI: 10.1016/j.rcradv.2025.200310
Case Study on Kitchen Waste Collection Materials: Comparing the Effects of Biobased Bags on Anaerobic Digestion
Authors: Veronika Kalauz-Simon; Péter Komáromy; Nándor Nemestóthy; Tamás Rózsenberszki; Janka Bobek-Nagy; Csilla Őze; Károly Kalauz; Katalin Kovács; Katalin Bélafi-Bakó
Published in: Chemical Engineering Transactions, 121, 109–114 (2025).
Summary: This study investigated how five commercially available kitchen waste collection bags, comprising three paper and two biodegradable plastic types, affected mesophilic batch anaerobic digestion. Paper bags increased methane and biogas yields by approximately 5–20% relative to the controls, whereas plastic bags produced similar or slightly lower yields. Recognisable fragments of both material types remained in the digestate at the end of the experiments. Under the conditions tested, the results indicate better compatibility of paper liners with anaerobic digestion and support the selection of collection materials suited to downstream biological treatment.
DOI: 10.3303/CET25121019 Full text
Enhancing Biomethanization of Kitchen Waste through Membrane Contactor-Mediated Hydrogen Supply
Authors: Veronika Kalauz-Simon; Péter Komáromy; Nándor Nemestóthy; Tamás Rózsenberszki; Róbert Fejes; Katalin Kovács; Katalin Bélafi-Bakó
Published in: Proceedings of the 33rd European Biomass Conference and Exhibition, Valencia, Spain, 9–12 June 2025, pp. 838–842. ISBN 978-88-89407-25-7.
Summary: This study combines anaerobic digestion of kitchen waste with the biological conversion of hydrogen into methane. Hydrogen was supplied directly to the reaction mixture through a PDMS membrane contactor to improve its availability to methanogenic microorganisms. The overall methane content of the biogas produced reached 76 ± 0.5%, while reactor headspace samples reached 98 ± 1.12% during the later stages of digestion. The findings demonstrate the potential of membrane-mediated hydrogen supply to connect kitchen waste recovery with power-to-methane technology.
DOI: 10.5071/33rdEUBCE2025-4CV.5.37 Publication page Conference presentation
Intensified Phase Contacting in Bioreactors without Mechanical Agitation (Keverő nélküli intenzív fázisérintkeztetés bioreaktorokban)
Authors: Péter Komáromy; Veronika Kalauz-Simon
Published in: Membrántechnika és ipari biotechnológia, 16(4), 54–61 (2025).
Summary: This article reviews reactor configurations that provide intensified phase contacting without conventional mechanical agitation. Practical examples cover spray columns, jet-loop reactors, microstructured reactors and membrane contactors. The discussion considers opportunities to improve mass transfer alongside energy requirements and the protection of biocatalysts. Applications include membrane-mediated hydrogen delivery to increase the methane content of biogas produced from kitchen waste.
Innovative utilization of organic waste: the intersection of kitchen waste and the Power-to-Gas concept (Szerves hulladékok innovatív hasznosítása: a konyhai hulladék és a Power-to-Gas koncepció találkozása)
Authors: Veronika Kalauz-Simon; Péter Komáromy; Nándor Nemestóthy; Tamás Rózsenberszki; Gábor Tóth; Róbert Fejes; Katalin Kovács; Katalin Bélafiné Bakó
Published in: Energiagazdálkodás, 66(1–2), 20–25 (2025).
Summary: This study investigates the integration of kitchen waste digestion with the power-to-gas concept through membrane-contactor-based hydrogen delivery. Hydrogen supply increased the methane content to 76 ± 0.5% across the total biogas produced, with later headspace samples reaching 98 ± 1.12%. However, total biogas production decreased, and early hydrogen addition adversely affected the initial stage of digestion. The findings identify the timing and intensity of hydrogen supply as important parameters for further process optimisation.
Olefin isomerisation–metathesis (ISOMET): recent advances in sustainable applications
Authors: Gábor Turczel; Ádám Erdélyi; Márton Nagyházi; Róbert Tuba
Published in: Organometallic Chemistry, Volume 46, pp. 1–29. The Royal Society of Chemistry (2025).
Summary: This book chapter reviews the principles and recent developments of tandem catalytic processes combining olefin isomerisation and metathesis. It explains how compatible homogeneous or heterogeneous catalysts can be used to adjust alkene chain lengths. Applications include the production of fine and value-added chemicals and the chemical valorisation of polymer waste. The review discusses catalyst systems and research directions relevant to more sustainable chemical manufacturing.
DOI: 10.1039/9781837070725-00001
Gas Phase Membrane Bioreactors
Authors: Katalin Bélafi-Bakó
Published in: Periodica Polytechnica Chemical Engineering, 69(3), 439–444 (2025).
Summary: This mini-review introduces gas-phase membrane bioreactors, which combine membrane contactors with biological processes. It describes membrane module configurations, operating principles and applications, including the removal of volatile organic compounds and other gaseous pollutants. Comparisons with conventional biological gas treatment highlight mass-transfer and operational advantages. The review also discusses construction costs, limitations in long-term stability and opportunities for further development.
Carboxylic Acid Production from Kitchen Waste and Sewage Sludge Digestate Inoculation via Acidogenic Fermentation at High Organic Load
Authors: Tamás Rózsenberszki; Veronika Kalauz-Simon; Róbert Fejes; Péter Bakonyi; László Koók; Róbert Kurdi; Nándor Nemestóthy; Katalin Bélafi-Bakó
Published in: Waste and Biomass Valorization, 16, 3733–3743 (2025).
Summary: This study produced volatile fatty acids from kitchen waste through acidogenic fermentation using sewage sludge digestate as inoculum. Experiments at high initial organic loads examined pH control, inoculum treatment, and batch and fed-batch operation. One daily pH-controlled experiment achieved a total volatile fatty acid yield of 0.31 g per g of volatile solids, with n-butyric acid predominating. The results support the potential of converting kitchen waste into organic acids suitable as chemical feedstocks.
DOI: 10.1007/s12649-025-02887-z
Tagetes erecta as a Nickel Phytoremediator: Insights into Accumulation and Growth Response
Authors: Eliza Molnár; Janka Bobek-Nagy; Tatjána Juzsakova; Róbert Kurdi; Renáta Rauch
Published in: Circular Economy and Sustainability, 5, 6483–6498 (2025).
Summary: This study examined nickel uptake and growth of Tagetes erecta in soils with different nickel concentrations. Approximately 60% of soil nickel remained bioavailable. Plants produced viable biomass at 2000 mg/kg dry matter soil contamination, but did not survive at 6000 mg/kg. The findings indicate both the potential and limitations of this species for nickel phytoremediation.
DOI: 10.1007/s43615-025-00603-6
Sustainable Waste Management in University Environment: Biowaste Recovery
Authors: Kinga Manuéla Berta; Róbert Kurdi; Anikó Reider; Zsuzsanna Banász
Published in: Circular Economy and Sustainability, 5, 6089–6111 (2025).
Summary: This research connects on-campus biowaste composting with community demand for the resulting compost. It combines European statistics, compost quality and plant growth experiments, and a university questionnaire survey. The compost met the relevant requirements for the parameters tested and supported plant growth. The study offers an example of institutional circular biowaste management and community participation.
DOI: 10.1007/s43615-025-00638-9
Machine Learning Classifier-Based Metrics Can Evaluate the Efficiency of Separation Systems
Authors: Éva Kenyeres; Alex Kummer; János Abonyi
Published in: Entropy, 26(7), 571 (2024).
Summary: This study demonstrates how metrics used to evaluate machine learning classifiers can also assess the efficiency of separation systems. Entropy- and information-gain-based measures were developed for both complete systems and individual operating units. ROC curves were used to investigate the selection of an optimal separation cut point. The methods were verified through simulations using a stochastic waste-sorting model.
Processing Kitchen Waste Using Bioprocesses (Konyhai hulladékok feldolgozása bio-folyamatok segítségével)
Authors: Péter Komáromy; Veronika Kalauz-Simon; Nándor Nemestóthy; Gábor Tóth; Katalin Kovács; Róbert Kurdi; Katalin Bélafiné Bakó
Published in: Membrántechnika és ipari biotechnológia, 15(4), 46–54 (2024).
Summary: This article reviews established and emerging biological routes for processing kitchen waste. Alongside composting and biogas production, it discusses the production of organic acids, biohydrogen and other valuable compounds. It considers challenges arising from variable feedstock composition and high moisture content, together with the importance of pretreatment and process control. Cascading biorefinery processes that generate multiple products are identified as a promising development pathway.
Ruthenium-catalyzed “open-loop” recycling of polyethylene via tandem isomerization-metathesis (ISOMET)
Authors: Vajk Farkas; Pascal Albrecht; Ádám Erdélyi; Márton Nagyházi; Beatrix Csutorás; Gábor Turczel; Norbert Miskolczi; Janka Bobek-Nagy; Ole Osterthun; Jürgen Klankermayer; Robert Tuba
Published in: Green Chemistry, 26, 10225–10231 (2024).
Summary: This study presents a two-step route for converting polyethylene waste into propylene, a valuable chemical feedstock. Slow pyrolysis first produced an olefin-rich oil, which was subsequently converted using ruthenium-based catalysts in an ethylene atmosphere. The tandem isomerisation–metathesis process was investigated in a 900 mL reactor and in repeated batch experiments. With post-consumer polyethylene-derived feedstock, the system achieved a total turnover number of 2788 mol of propylene per mol of metathesis catalyst.