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Processes
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Advanced Technology of Waste Treatment
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Advanced Technology of Waste Treatment

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

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 57943

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Daniel Vollprecht

E-Mail Website
Guest Editor
Chair of Waste Processing Technology and Waste Management, Montanuniversität Leoben, 8700 Leoben, Austria
Interests: wastes; landfills; contaminate sites; slags
Dr. Renato Sarc

E-Mail Website
Guest Editor
Chair of Waste Processing Technology and Waste Management, Montanuniversität Leoben, 8700 Leoben, Austria
Interests: innovative waste treatment; waste management; municipal and commercial non-hazardous waste

Special Issue Information

Dear Colleagues,

The protection of human health and the environment, as well as the sustainable use of natural resources, requires chemical, biological, and physical treatment of wastes. This refers to the conditioning (e.g., drying, washing, comminution, rotting, stabilization, neutralization, agglomeration, homogenization), conversion (e.g., incineration, pyrolysis, gasification, dissolution, evaporation), and separation (classification, direct and indirect (i.e., sensor-based) sorting) of all kinds of wastes to follow the principles of the waste hierarchy (i.e., prevention (not addressed by this issue), preparation for re-use, recycling, other recovery and landfilling). Longstanding challenges include the increase of yield and purity of recyclable fractions and the removal or destruction of pollutants from the circular economy.

This Special Issue on “Advanced Technology of Waste Treatment” will collect high-quality research studies addressing challenges on the broad area of chemical, biological, and physical treatment of wastes. Topics include but are not limited to the following:

  • Mechanical processing of municipal solid wastes (including separately collected and residual wastes as well as wastes from landfill mining projects)
  • Mechanical processing of industrial and mining wastes
  • Biological treatment of organic wastes
  • Thermal treatment of municipal solid wastes
  • Thermal conditioning of industrial wastes and by-products
  • Physico-chemical treatment of hazardous wastes

Dr. Daniel Vollprecht
Dr. Renato Sarc
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 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. 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

  • Preparation for re-use
  • Recycling
  • Energy recovery
  • Preparation for disposal
  • Municipal solid waste
  • Solid recovered fuels
  • Industrial and mining waste
  • Mechanical processing
  • Sensor-based processing
  • Biological treatment
  • Thermal treatment

Published Papers (16 papers)

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Editorial

Jump to: Research, Review

3 pages, 178 KiB  
Editorial
Special Issue on “Advanced Technology of Waste Treatment”
by Daniel Vollprecht and Renato Sarc
Processes 2022, 10(2), 217; https://doi.org/10.3390/pr10020217 - 24 Jan 2022
Viewed by 1743
Abstract
The protection of human health and the environment (representing the main reason for waste management), as well as the sustainable use of natural resources, requires chemical, biological, physical and thermal treatment of wastes [...] Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)

Research

Jump to: Editorial, Review

14 pages, 1391 KiB  
Article
Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Effect on Phosphorus Recovery, Yield, and Energy Value of Hydrochar
by Vicky Shettigondahalli Ekanthalu, Satyanarayana Narra, Jan Sprafke and Michael Nelles
Processes 2021, 9(4), 618; https://doi.org/10.3390/pr9040618 - 31 Mar 2021
Cited by 18 | Viewed by 2812
Abstract
The high moisture content present in sewage sludge hinders the use of sewage sludge in incineration or energy application. This limitation of moisture present in sewage sludge can be obviated by using the hydrothermal carbonization (HTC) process. In sewage sludge management, the HTC [...] Read more.
The high moisture content present in sewage sludge hinders the use of sewage sludge in incineration or energy application. This limitation of moisture present in sewage sludge can be obviated by using the hydrothermal carbonization (HTC) process. In sewage sludge management, the HTC process requires less energy compared to other conventional thermo–chemical management processes. The HTC process produces energy-rich hydrochar products and simultaneously enables phosphorus recovery. This study investigates the influence of organic acids, inorganic acid, and alkali as additives on phosphorus transformation, yield, proximate analysis and the heating value of subsequently produced hydrochar. The analysis includes various process temperatures (200 °C, 220 °C, and 240 °C) in the presence of deionized water, acids (0.1 M and 0.25 M; H2SO4, HCOOH, CH3COOH), and alkali (0.1 M and 0.25 M; NaOH) solutions as feed water. The results show that phosphorus leaching into the process-water, hydrochar yield, proximate analysis, and the heating value of produced hydrochar is pH- and temperature-dependent, and particularly significant in the presence of H2SO4. In contrast, utilization of H2SO4 and NaOH as an additive has a negative influence on the heating value of produced hydrochar. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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16 pages, 9269 KiB  
Article
Chemical Recycling of WEEE Plastics—Production of High Purity Monocyclic Aromatic Chemicals
by Tobias Rieger, Jessen C. Oey, Volodymyr Palchyk, Alexander Hofmann, Matthias Franke and Andreas Hornung
Processes 2021, 9(3), 530; https://doi.org/10.3390/pr9030530 - 16 Mar 2021
Cited by 14 | Viewed by 3758
Abstract
More than 200 kg real waste electrical and electronic equipment (WEEE) shredder residues from a German dismantling plant were treated at 650 °C in a demonstration scale thermochemical conversion plant. The focus within this work was the generation, purification, and analysis of pyrolysis [...] Read more.
More than 200 kg real waste electrical and electronic equipment (WEEE) shredder residues from a German dismantling plant were treated at 650 °C in a demonstration scale thermochemical conversion plant. The focus within this work was the generation, purification, and analysis of pyrolysis oil. Subsequent filtration and fractional distillation were combined to yield basic chemicals in high purity. By means of fractional distillation, pure monocyclic aromatic fractions containing benzene, toluene, ethylbenzene, and xylene (BTEX aromatics) as well as styrene and α-methyl styrene were isolated for chemical recycling. Mass balances were determined, and gas chromatography–mass spectrometry (GC-MS) as well as energy dispersive X-ray fluorescence (EDXRF) measurements provided data on the purity and halogen content of each fraction. This work shows that thermochemical conversion and the subsequent refining by fractional distillation is capable of recycling WEEE shredder residues, producing pure BTEX and other monocyclic aromatic fractions. A significant decrease of halogen content (up to 99%) was achieved with the applied methods. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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16 pages, 2462 KiB  
Article
Advancing Plastic Recycling by Wet-Mechanical Processing of Mixed Waste Fractions
by Daniel Schwabl, Markus Bauer and Markus Lehner
Processes 2021, 9(3), 493; https://doi.org/10.3390/pr9030493 - 9 Mar 2021
Cited by 7 | Viewed by 3867
Abstract
In this paper, an arc was drawn over ten years of research activities from three chairs of the Montanuniversitaet Leoben, as well as industrial partners. The superior objective of this research effort was to develop a wet-mechanical process for the recovery of polyolefin [...] Read more.
In this paper, an arc was drawn over ten years of research activities from three chairs of the Montanuniversitaet Leoben, as well as industrial partners. The superior objective of this research effort was to develop a wet-mechanical process for the recovery of polyolefin concentrates (90 wt% polyolefins) from mixed waste fraction for use in chemical recycling and to advance this new technology to commercial maturity. As a bridge technology, it would close the gap between state-of-the-art dry processing of mixed plastic waste materials and chemical plastic recycling via thermo-chemical conversion. The methods used were mainly tested in a lab-scale plant with a throughput capacity of 50 to 200 kg/h depending on the bulk density of the used feedstock. Further studies for the treatment and usage of the main products and by-products, as well as chemical analyses of them, were completed during the investigation. Within these series of tests, polyolefin concentrates, which satisfied the requirements for chemical recycling, could be recovered. With these data, a concept for an industrial pilot plant was developed and evaluated from an economic point of view. According to this evaluation, the realization of such an industrial pilot plant can be recommended. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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21 pages, 3648 KiB  
Article
Distribution-Independent Empirical Modeling of Particle Size Distributions—Coarse-Shredding of Mixed Commercial Waste
by Karim Khodier and Renato Sarc
Processes 2021, 9(3), 414; https://doi.org/10.3390/pr9030414 - 25 Feb 2021
Cited by 5 | Viewed by 2080
Abstract
Particle size distributions (PSDs) belong to the most critical properties of particulate materials. They influence process behavior and product qualities. Standard methods for describing them are either too detailed for straightforward interpretation (i.e., lists of individual particles), hide too much information (summary values), [...] Read more.
Particle size distributions (PSDs) belong to the most critical properties of particulate materials. They influence process behavior and product qualities. Standard methods for describing them are either too detailed for straightforward interpretation (i.e., lists of individual particles), hide too much information (summary values), or are distribution-dependent, limiting their applicability to distributions produced by a small number of processes. In this work the distribution-independent approach of modeling isometric log-ratio-transformed shares of an arbitrary number of discrete particle size classes is presented. It allows using standard empirical modeling techniques, and the mathematically proper calculation of confidence and prediction regions. The method is demonstrated on coarse-shredding of mixed commercial waste from Styria in Austria, resulting in a significant model for the influence of shredding parameters on produced particle sizes (with classes: >80 mm, 30–80 mm, 0–30 mm). It identifies the cutting tool geometry as significant, with a p-value < 10−5, while evaluating the gap width and shaft rotation speed as non-significant. In conclusion, the results question typically chosen operation parameters in practice, and the applied method has proven to be valuable addition to the mathematical toolbox of process engineers. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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12 pages, 2032 KiB  
Article
Optimization of Metal Recovery from MSWI Fly Ash by Acid Leaching: Findings from Laboratory- and Industrial-Scale Experiments
by Gisela Weibel, Anna Zappatini, Mirjam Wolffers and Stefan Ringmann
Processes 2021, 9(2), 352; https://doi.org/10.3390/pr9020352 - 14 Feb 2021
Cited by 12 | Viewed by 4219
Abstract
A major part of Swiss fly ashes (FA) from municipal solid waste incineration (MSWI) are treated with the acid fly ash leaching process (FLUWA) in order to recover heavy metals prior to deposition. The FLUWA process uses scrub water from wet flue gas [...] Read more.
A major part of Swiss fly ashes (FA) from municipal solid waste incineration (MSWI) are treated with the acid fly ash leaching process (FLUWA) in order to recover heavy metals prior to deposition. The FLUWA process uses scrub water from wet flue gas cleaning to leach heavy metals from FA. The leaching efficiency is strongly dependent on the leaching conditions (e.g., pH, Eh, L/S-ratio). This case study presents the optimization of the FLUWA process at the MSWI plant Linth, Switzerland, through determination of ideal process parameters for optimal metal recovery. By means of laboratory- and industrial-scale experiments, the process was adjusted towards a more efficient leaching of Zn, Pb, Cu, and Cd. This included the use of an oxidizing agent (hydrogen peroxide). Laboratory experiments proved to be a powerful tool for simulating process optimizations at industrial scale. An ideal leaching pH of 3.8 was determined and it was observed that the process stability is significantly influenced by the L/S-ratio applied to the leaching process. In the course of the study, the recovery could be improved to 67% Zn, 66% Pb, 30% Cu, and 91% Cd. It can be concluded that for optimal metal recovery the process has to be individually adjusted to the composition of the processed FA and scrub water of each specific FLUWA process. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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17 pages, 18440 KiB  
Article
Recovery of Raw Materials from Ceramic Waste Materials for the Refractory Industry
by Severin Seifert, Sebastian Dittrich and Jürgen Bach
Processes 2021, 9(2), 228; https://doi.org/10.3390/pr9020228 - 26 Jan 2021
Cited by 9 | Viewed by 3553
Abstract
Products of the refractory industry are key for the production of heavy industry goods such as steel and iron, cement, aluminum and glass. Corresponding industries are dependent on thermal processes to manufacture their products, which in turn would not be possible if there [...] Read more.
Products of the refractory industry are key for the production of heavy industry goods such as steel and iron, cement, aluminum and glass. Corresponding industries are dependent on thermal processes to manufacture their products, which in turn would not be possible if there were no refractory materials, such as refractory bricks or refractory mixes. For the production of refractory materials, primary raw materials or semi-finished products such as corundum, bauxite or zircon are used. Industrial recycling of refractory raw materials would reduce dependencies, conserve resources and reduce global CO2 emissions. Today, only a small quantity of the refractory materials used can be recycled because raw materials (regenerates) obtained from end-of-life materials are of insufficient quality. In this study, regenerates from different refractory waste products could be obtained using the innovative processing method of electrodynamic fragmentation. It was shown that these regenerates have a high chemical purity and are therefore of high quality. It could be confirmed that the use of these regenerates in refractory materials does not affect the characteristic properties, such as refractoriness and mechanical strength. Thus, electrodynamic fragmentation is a process, which is able to provide high-quality raw materials for the refractory industry from used materials. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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15 pages, 1660 KiB  
Article
Waste Wood Fly Ash Treatment in Switzerland: Effects of Co-Processing with Fly Ash from Municipal Solid Waste on Cr(VI) Reduction and Heavy Metal Recovery
by Mirjam Wolffers, Gisela Weibel and Urs Eggenberger
Processes 2021, 9(1), 146; https://doi.org/10.3390/pr9010146 - 13 Jan 2021
Cited by 3 | Viewed by 1921
Abstract
In Switzerland, waste wood fly ash (WWFA) must be treated before deposition on landfills due to its high pollutant load (Cr(VI) and heavy metals). Acid fly ash leaching, the process used for heavy metal recovery from municipal solid waste incineration fly ash (MSWIFA), [...] Read more.
In Switzerland, waste wood fly ash (WWFA) must be treated before deposition on landfills due to its high pollutant load (Cr(VI) and heavy metals). Acid fly ash leaching, the process used for heavy metal recovery from municipal solid waste incineration fly ash (MSWIFA), represents a possible treatment for heavy metal depletion and Cr(VI) reduction in WWFA. The co-processing of WWFA with MSWIFA during acid fly ash leaching was investigated in laboratory- and industrial-scale experiments with different setups. Of interest were the effects on heavy metal recovery efficiency, the successful outcome of Cr(VI) reduction and consumption of neutralizing chemicals (HCl, H2O2). Detailed chemical and mineralogical characterization of two WWFA types and MSWIFA showed that MSWIFA has higher concentrations in potentially harmful elements than WWFA. However, both WWFA types showed high concentrations in Pb and Cr(VI), and therefore need treatment prior to deposition. Depending on the waste wood proportion and quality, WWFA showed chemical and mineralogical differences that affect leaching behavior. In all experimental setups, successful Cr(VI) reduction was achieved. However, WWFA showed higher consumption of HCl and H2O2, the latter resulting in a particularly negative effect on the recovery of Pb and Cu. Thus, co-processing of smaller WWFA portions could be expedient in order to diminish the negative effects of Pb and Cu recovery. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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15 pages, 4082 KiB  
Article
Pyrometallurgical Lithium-Ion-Battery Recycling: Approach to Limiting Lithium Slagging with the InduRed Reactor Concept
by Stefan Windisch-Kern, Alexandra Holzer, Christoph Ponak and Harald Raupenstrauch
Processes 2021, 9(1), 84; https://doi.org/10.3390/pr9010084 - 2 Jan 2021
Cited by 43 | Viewed by 7880
Abstract
The complexity of the waste stream of spent lithium-ion batteries poses numerous challenges on the recycling industry. Pyrometallurgical recycling processes have a lot of benefits but are not able to recover lithium from the black matter since lithium is slagged due to its [...] Read more.
The complexity of the waste stream of spent lithium-ion batteries poses numerous challenges on the recycling industry. Pyrometallurgical recycling processes have a lot of benefits but are not able to recover lithium from the black matter since lithium is slagged due to its high oxygen affinity. The presented InduRed reactor concept might be a promising novel approach, since it does not have this disadvantage and is very flexible concerning the chemical composition of the input material. To prove its basic suitability for black matter processing, heating microscope experiments, thermogravimetric analysis and differential scanning calorimetry have been conducted to characterize the behavior of nickel rich cathode materials (LiNi0.8Co0.15Al0.05O2 and LiNi0.33Mn0.33Co0.33O2) as well as black matter from a pretreatment process under reducing conditions. Another experimental series in a lab scale InduRed reactor was further used to investigate achievable transfer coefficients for the metals of interest. The promising results show technically feasible reaction temperatures of 800 ∘C to 1000 ∘C and high recovery potentials for nickel, cobalt and manganese. Furthermore, the slagging of lithium was largely prevented and a lithium removal rate of up to 90% of its initial mass was achieved. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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12 pages, 680 KiB  
Article
Lithium-Ion Batteries as Ignition Sources in Waste Treatment Processes—A Semi-Quantitate Risk Analysis and Assessment of Battery-Caused Waste Fires
by Thomas Nigl, Mirjam Baldauf, Michael Hohenberger and Roland Pomberger
Processes 2021, 9(1), 49; https://doi.org/10.3390/pr9010049 - 29 Dec 2020
Cited by 13 | Viewed by 5517
Abstract
Increasing occurrences of waste fires that are caused by improperly discarded lithium-based portable batteries threaten the whole waste management sector in numerous countries. Studies showed that high quantities of these batteries have been found in several municipal solid waste streams in recent years [...] Read more.
Increasing occurrences of waste fires that are caused by improperly discarded lithium-based portable batteries threaten the whole waste management sector in numerous countries. Studies showed that high quantities of these batteries have been found in several municipal solid waste streams in recent years in Austria. This article reveals the main influence factors on the risk of lithium-based batteries in their end-of-life and it focuses on the quantification of damages to portable batteries during waste treatment processes. Hazards are identified and analysed and potential risks in waste management systems are comprehensively assessed. In two scenarios, the results showed that the potential risks are too high to maintain a sustainable form of waste management. According to the assessment, a small fire in a collection vehicle is located in the risk graph’s yellow region (as low as reasonably practicable, ALARP), while a fully developed fire in a treatment plant has to be classified as an unacceptable risk (red region of risk graph). Finally, basic recommendations for action were made. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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15 pages, 4007 KiB  
Article
Lumped Kinetic Modeling of Polypropylene and Polyethylene Co-Pyrolysis in Tubular Reactors
by Andreas E. Lechleitner, Teresa Schubert, Wolfgang Hofer and Markus Lehner
Processes 2021, 9(1), 34; https://doi.org/10.3390/pr9010034 - 25 Dec 2020
Cited by 18 | Viewed by 4223
Abstract
The recycling rates, especially those from plastic packaging waste, have to be increased according to the European Union directive in the next years. Besides many other technologies, the pyrolysis of plastic wastes seems to be an efficient supplementary opportunity to treat mixed and [...] Read more.
The recycling rates, especially those from plastic packaging waste, have to be increased according to the European Union directive in the next years. Besides many other technologies, the pyrolysis of plastic wastes seems to be an efficient supplementary opportunity to treat mixed and unpurified plastic streams. For this reason, a pyrolysis process was developed for the chemical recycling of hydrocarbons from waste polyolefins. The obtained products can be further processed and upgraded in crude oil refineries, so that also monomers can be recovered, which are used for the plastic polymerization again. However, to achieve a scale up to a demo plant, a kinetic model for predicting the yields of the plastic pyrolysis in a tubular reactor is needed. For this reason, a pilot plant was built, in which different plastics and carrier fluids can be tested. Based on the data generated at the pilot plant, a very practical and suitable model was found to describe the plastic co-pyrolysis of the carrier fluid with polypropylene (PP) and low density and high density polyethylene (HDPE and LDPE), respectively. The physical and chemical mechanisms of the co-pyrolysis in the tubular reactor are successfully investigated. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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17 pages, 5644 KiB  
Article
Comparative Analysis of the Behaviour of Marine Litter in Thermochemical Waste Treatment Processes
by Johann Hee, Kai Schlögel, Simone Lechthaler, Jacqueline Plaster, Kristina Bitter, Lars Mathias Blank and Peter Quicker
Processes 2021, 9(1), 13; https://doi.org/10.3390/pr9010013 - 23 Dec 2020
Cited by 6 | Viewed by 3513
Abstract
Plastic in the ocean, especially plastic on the ocean surface is not only researched intensively but also photos and reports rise awareness of the challenge in the general public. While research is concerned with the fate of marine litter in the environment, recycling [...] Read more.
Plastic in the ocean, especially plastic on the ocean surface is not only researched intensively but also photos and reports rise awareness of the challenge in the general public. While research is concerned with the fate of marine litter in the environment, recycling of these materials after collection is rarely addressed, mainly because there is neither considerable data on composition nor a suggested process to do so. This study is the first to analyse and evaluate chemical recycling (pyrolysis, gasification) and energy recovery (incineration) of marine litter. Two heterogenous marine litter samples from Sylt and Norderney, North Sea, Germany, were analysed, consisting of six different material groups. Agricultural mulch foil was used as reference material. The thermochemical treatment processes were reproduced by thermogravimetric analysis. Furthermore, pyrolysis trials on a semi-technical scale were conducted and the residues were analysed by proximate, ultimate and X-ray fluorescence analysis. The results indicate that heterogeneous and weathered material mixtures can be treated by thermochemical processes. Finally, the pyrolysis condensates are discussed as substrate for biotechnological upcycling. In summary, we present a comprehensive approach from the material characterisation of marine litter to the analysis of three different thermochemical treatment processes and the possibility to use the generated pyrolysis condensate for subsequent upcycling. The data collected form the basis for the evaluation and application of possible treatment options for the collected marine litter. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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13 pages, 1965 KiB  
Article
Inventory of MSWI Fly Ash in Switzerland: Heavy Metal Recovery Potential and Their Properties for Acid Leaching
by Wolfgang Zucha, Gisela Weibel, Mirjam Wolffers and Urs Eggenberger
Processes 2020, 8(12), 1668; https://doi.org/10.3390/pr8121668 - 17 Dec 2020
Cited by 12 | Viewed by 2887
Abstract
From the year 2021 on, heavy metals from Swiss municipal solid waste incineration (MSWI) fly ash (FA) must be recovered before landfilling. This is predominantly performed by acid leaching. As a basis for the development of defined recovery rates and for the implementation [...] Read more.
From the year 2021 on, heavy metals from Swiss municipal solid waste incineration (MSWI) fly ash (FA) must be recovered before landfilling. This is predominantly performed by acid leaching. As a basis for the development of defined recovery rates and for the implementation of the recovery process, the authorities and plant operators need information on the geochemical properties of FA. This study provides extended chemical and mineralogical characterization of all FA produced in 29 MSWI plants in Switzerland. Acid neutralizing capacity (ANC) and metallic aluminum (Al0) were additionally analyzed to estimate the effort for acid leaching. Results show that all FA samples are composed of similar constituents, but their content varies due to differences in waste input and incineration conditions. Based on their geochemical properties, the ashes could be divided into four types describing the leachability: very good (6 FA), good (10 FA), moderate (5 FA), and poor leaching potential (8 FA). Due to the large differences it is suggested that the required recovery rates are adjusted to the leaching potential. The quantity of heavy metals recoverable by acid leaching was estimated to be 2420 t/y Zn, 530 t/y Pb, 66 t/y Cu and 22 t/y Cd. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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19 pages, 3007 KiB  
Article
Municipal Solid Waste as Secondary Resource: Selectively Separating Cu(II) from Highly Saline Fly Ash Extracts by Polymer-Assisted Ultrafiltration
by Christine Hettenkofer, Stephan Fromm and Michael Schuster
Processes 2020, 8(12), 1662; https://doi.org/10.3390/pr8121662 - 16 Dec 2020
Cited by 3 | Viewed by 1717
Abstract
Urban mining from fly ash resulting from municipal solid waste incineration (MSWI) is becoming more and more important due to the increasing scarcity of supply-critical metals. Metal extraction from acid fly ash leaching has already been established. In this context selective Cu recovery [...] Read more.
Urban mining from fly ash resulting from municipal solid waste incineration (MSWI) is becoming more and more important due to the increasing scarcity of supply-critical metals. Metal extraction from acid fly ash leaching has already been established. In this context selective Cu recovery is still a challenge. Therefore, our purpose was the separation of Cu(II) from MSWI fly ash extracts by polymer-assisted ultrafiltration (PAUF). We investigated three polyethyleneimines (PEIs) with regard to metal retention, Cu(II) selectivity, Cu(II) loading capacity, and the viscosity of the PEI containing solutions. A demanding challenge was the highly complex matrix of the fly ash extracts, which contain up to 16 interfering metal ions in high concentrations and a chloride content of 60 g L−1. Overcoming that, Cu(II) was selectively enriched and separated from real fly ash extract at pH 3.0. At pH 1.0, a PEI-free Cu(II) concentrate was obtained and PEIs could be regenerated for reuse in further separation cycles. The PAUF conditions developed at laboratory scale were successfully transferred to pilot scale, and hyperbranched PEI (HB-PEI) was found to be the most suitable reagent for PAUF in a technical scale. Moreover, HB-PEI enables photometric control of the Cu(II) enrichment. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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Review

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29 pages, 8762 KiB  
Review
The “ReWaste4.0” Project—A Review
by Renato Sarc
Processes 2021, 9(5), 764; https://doi.org/10.3390/pr9050764 - 27 Apr 2021
Cited by 6 | Viewed by 2275
Abstract
ReWaste4.0 is an innovative and cooperative K-Project in the period 2017–2021. Through ReWaste4.0 the transformation of the non-hazardous mixed municipal and commercial waste treatment industry towards a circular economy has started by investigating and applying the new approaches of the Industry 4.0. Vision [...] Read more.
ReWaste4.0 is an innovative and cooperative K-Project in the period 2017–2021. Through ReWaste4.0 the transformation of the non-hazardous mixed municipal and commercial waste treatment industry towards a circular economy has started by investigating and applying the new approaches of the Industry 4.0. Vision of the ReWaste4.0 is, among others, the development of treatment plants for non-hazardous waste into a “Smart Waste Factory” in which a digital communication and interconnection between material quality and machine as well as plant performance is reached. After four years of research and development, various results have been gained and the present review article summarizes, links and discuss the outputs (especially from peer-reviewed papers) of seven sub-projects, in total, within the K-project and discusses the main findings and their relevance and importance for further development of the waste treatment sector. Results are allocated into three areas, namely: contaminants in mixed waste and technical possibilities for their reduction as well as removal; secondary raw and energy materials in mixed waste and digitalization in waste characterization and treatment processes for mixed waste. The research conducted in ReWaste4.0 will be continued in ReWaste F for further development towards a particle-, sensor- and data-based circular economy in the period 2021–2025. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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20 pages, 920 KiB  
Review
The EU Training Network for Resource Recovery through Enhanced Landfill Mining—A Review
by Daniel Vollprecht, Lieven Machiels and Peter Tom Jones
Processes 2021, 9(2), 394; https://doi.org/10.3390/pr9020394 - 22 Feb 2021
Cited by 14 | Viewed by 3936
Abstract
The “European Union Training Network for Resource Recovery Through Enhanced Landfill Mining (NEW-MINE)” was a European research project conducted between 2016 and 2020 to investigate the exploration of and resource recovery from landfills as well as the processing of the excavated waste and [...] Read more.
The “European Union Training Network for Resource Recovery Through Enhanced Landfill Mining (NEW-MINE)” was a European research project conducted between 2016 and 2020 to investigate the exploration of and resource recovery from landfills as well as the processing of the excavated waste and the valorization of the obtained waste fractions using thermochemical processes. This project yielded more than 40 publications ranging from geophysics via mechanical process engineering to ceramics, which have not yet been discussed coherently in a review publication. This article summarizes and links the NEW-MINE publications and discusses their practical applicability in waste management systems. Within the NEW-MINE project in a first step concentrates of specific materials (e.g., metals, combustibles, inert materials) were produced which might be used as secondary raw materials. In a second step, recycled products (e.g., inorganic polymers, functional glass-ceramics) were produced from these concentrates at the lab scale. However, even if secondary raw materials or recycled products could be produced at a large scale, it remains unclear if they can compete with primary raw materials or products from primary raw materials. Given the ambitions of transition towards a more circular economy, economic incentives are required to make secondary raw materials or recycled products from enhanced landfill mining (ELFM) competitive in the market. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
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