Corrigendum to: Qualitative analysis of post-consumer and post-industrial waste via near-infrared, visual and induction identification with experimental sensor-based sorting setup.

[This corrects the article DOI: 10.1016/j.mex.2022.101686.].

Qualitative analysis of post-consumer and post-industrial waste via near-infrared, visual and induction identification with experimental sensor-based sorting setup.

Sensor-based sorting in waste management is a method to separate valuable material or contaminants from a waste stream. Depending on the separation property different types of sensors are used. Separation properties and their corresponding sensors are e.g. molecular composition with near-infrared sensors, colour with visual spectroscopy or colour line scan cameras, or electric conductivity with electromagnetic sensors. The methods described in this paper deal with the development of sorting models for a specific near-infrared, a visual spectroscopy and an induction sensor. For near-infrared and visual spectroscopy software is required to create sorting models, while for induction only machine settings have to be adjusted and optimized for a specific sorting task. These sensors are installed in the experimental sensor-based sorting setup at the Chair of Waste Processing Technology and Waste Management located at the Montanuniversitaet Leoben. This sorting stand is a special designed machine for the university to make experiments on sensor-based sorting in lab scale. It can be used for a variety of waste streams depending on the grain size and the pre-conditioning for the sensor-based sorting machine. In detail the methods to create these sorting models are described and validated with plastic, glass and metal waste.•Near-infrared spectroscopy measures the molecular composition of near-infrared-active particles.•Visual spectroscopy measures the absorption of visible light by chemical compounds.•Induction sensors use induced currents to detect nearby metal objects.

Origins of major and minor ash constituents of solid recovered fuel for co-processing in the cement industry.

Solid recovered fuel (SRF) ash consists of element oxides, which are valuable materials for cement manufacturers. When SRF is co-processed in the cement industry, its mineral content is incorporated into the clinker. Therefore, from a technical perspective, SRF ash is recycled. However, since recycling processes for materials that may be present in SRF exist, and since recycling goals are defined for different waste types, understanding the origin of these ash constituents and the contribution of different materials to the Recycling-index (R-index, i.e., the material-recyclable share of SRF) is important. In this work, the origins of Al, Ca, Fe, Si, Ti, Mg, Na, K, S, and P were first reviewed. Subsequently, ten SRF samples were sorted, and the ash content and composition of the sorting fractions (e.g., <10 mm, plastics, paper&cardboard) determined. Additionally, selected samples of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), liquid packaging board (LPB), wood, and paper&cardboard (P&C) extracted from SRF were investigated. The results demonstrated that the materials that contributed most of the valuable oxides and ash content, and thereby to the R-index of SRF, are mixed or composite fractions, for example, the fine fraction, composites, and the sorting residues. Except for the composite LPB, no other material recovery options exist for most of these fractions. For this reason, the recycling of mixed and soiled materials or residues in the cement industry may be considered a complementary option to existing recycling processes.

Grain size dependent distribution of different plastic types in coarse shredded mixed commercial and municipal waste.

The Waste Framework Directive regulates the recycling of waste in Europe. The definition of waste is specified in different guidelines and regulations. Mixed Commercial Waste is waste from industry which is not collected separately. Currently there is little known about its composition. Mixed Municipal Waste, on the other hand, is household waste that cannot be attributed to any separately collected waste fraction (AdSLR, 2012). Both wastes are currently treated focussing on the generation of refuse-derived fuel rather than on the separation of recyclables (mainly performed for metals). The purpose of this paper is to characterise the amounts of various plastic types contained in different grain sizes of two-dimensional and three-dimensional plastics sorting fractions of both waste types. Nine types of plastics were identified as potential recycling materials for which recycling processes as well as a market are available. Both wastes were shredded, sampled and sieved into nine grain size classes (GSC). Fractions coarser than 20 mm were sorted, generating a 'plastics-2D' and a 'plastics-3D' fraction among others. The two plastics fractions were further characterised as plastic types using a near-infrared sensor and a Fourier-transform infrared spectrometer. The results reveal a potential for plastic recycling through mechanical and feedstock recycling options for the examined wastes. Certain types of plastics, of certain dimensionality, tend to come in certain grain sizes, which is essential for mechanical enrichment and discharge.

Origins and carriers of Sb, As, Cd, Cl, Cr, Co, Pb, Hg, and Ni in mixed solid waste - A literature-based evaluation.

Antimony, arsenic, cadmium, chlorine, chromium, cobalt, lead, mercury, nickel and their compounds are commonly used in the industrial production of various goods. At the end of the product life cycle, these elements enter the waste system as constituents of the products. Mixed municipal and commercial wastes are landfilled, biologically treated, incinerated, and/or processed in mechanical treatment plants to yield solid recovered fuel (SRF). In all these cases, inorganic contaminants that are present in the input waste material play a significant role. In mechanical waste treatment, materials containing high concentrations of these elements (contaminant carriers) can be selectively removed (e.g. by infrared sorters) to improve the output quality, but prior knowledge about the contaminant carriers is required. This paper reviews several waste-related publications in order to identify carriers of Sb, As, Cd, Cl, Cr, Co, Pb, Hg, and Ni in mixed municipal and commercial waste. Identified contaminant carriers are listed alongside ranges for expected concentrations. Furthermore, the data are combined with information on industrial applications and contaminant concentrations in products in order to discuss the reasons for the presence of the respective elements in the carriers. Generally, besides inerts or metals, identified contaminant carriers often include plastics, composite materials, leather products, textiles, rubber, electronic waste, and batteries. Moreover, it is evaluated how individual contaminant carriers are reflected by chemical waste analyses. While the findings of the paper can be applied to different waste treatment options, the discussion focuses on SRF, which is the main output of mechanical treatment plants.

Design, quality and quality assurance of solid recovered fuels for the substitution of fossil feedstock in the cement industry - Update 2019.

Production, quality and quality assurance, as well as co-incineration of solid recovered fuels in cement industry, have become state-of-the-art in the European cement industry. At the global level, average thermal substitution rate is about 17%, whereby, only 13% in Canada and in the USA 16%, while in the European Union 28 it is about 44% (i.e. 11,300,000 t waste fuels utilised in 2016). In Austria, thermal substitution rate was ca. 80% in 2017, which was worldwide the highest one. Regarding solid recovered fuels for the cement industry, two types are relevant, namely solid recovered fuels PREMIUM Quality and solid recovered fuels MEDIUM Quality. In the case study shown, solid recovered fuels PREMIUM Quality from 11 and solid recovered fuels MEDIUM Quality from nine different solid recovered fuels production plants have been investigated. Investigations consist of sorting and sieving analyses (for PREMIUM), as well as physical-chemical analyses (for both solid recovered fuels types) according to the (inter)national standards (i.e. Austrian 'ÖNORM', European 'EN' standards and CEN TC 343 guidelines). The results gained from the first investigation were published in 2014 and here, results of further investigations are updated for 2016 and 2018 and confronted with legal and market relevant requirements. During the investigation, not enough parallel samples could be investigated and therefore no adequate scientific statistical analyses could be elaborated but a more practical indicative interpretation has been made. Finally, it can be confirmed, that all investigated solid recovered fuels fulfil the Austrian legal and international solid recovered fuels and co-incineration market requirements.

Digitalisation and intelligent robotics in value chain of circular economy oriented waste management - A review.

The general aim of circular economy is the most efficient and comprehensive use of resources. In order to achieve this goal, new approaches of Industry 4.0 are being developed and implemented in the field of waste management. The innovative K-project: Recycling and Recovery of Waste 4.0 - "ReWaste4.0" deals with topics such as digitalisation and the use of robotic technologies in waste management. Here, a summary of the already published results in these areas, which were divided into the four focused topics, is given: Collection and Logistics, Machines and waste treatment plants, Business models and Data Tools. Presented are systems and methods already used in waste management, as well as technologies that have already been successfully applied in other industrial sectors and will also be relevant in the waste management sector for the future. The focus is set on systems that could be used in waste treatment plants or machines in the future in order to make treatment of waste more efficient. In particular, systems which carry out the sorting of (mixed) waste via robotic technologies are of interest. Furthermore "smart bins" with sensors for material detection or level measurement, methods for digital image analysis and new business models have already been developed. The technologies are often based on large amounts of data that can contribute to increase the efficiency within plants. In addition, the results of an online market survey of companies from the waste management industry on the subject of waste management 4.0 or "digital readiness" are summarized.

Dynamic visualisation of municipal waste management performance in the EU using Ternary Diagram method.

This contribution describes the dynamic visualisation of European (EU 28) municipal waste management performance, using the Ternary Diagram Method. Municipal waste management performance depends primarily on three treatment categories: recycling & composting, incineration and landfilling. The framework of current municipal waste management including recycling targets, etc. is given by the Waste Framework Directive - 2008/98/EC. The proposed Circular Economy Package should stimulate Europe's transition towards more sustainable resources and energy oriented waste management. The Package also includes a revised legislative proposal on waste that sets ambitious recycling rates for municipal waste for 2025 (60%) and 2030 (65%). Additionally, the new calculation method for monitoring the attainment of the targets should be applied. In 2014, ca. 240 million tonnes of municipal waste were generated in the EU. While in 1995, 17% were recycled and composted, 14% incinerated and 64% landfilled, in 2014 ca. 71% were recovered but 28% landfilled only. Considering the treatment performance of the individual EU member states, the EU 28 can be divided into three groups, namely: "Recovery Countries", "Transition Countries" and "Landfilling Countries". Using Ternary Diagram Method, three types of visualization for the municipal waste management performance have been investigated and extensively described. Therefore, for better understanding of municipal waste management performance in the last 20years, dynamic visualisation of the Eurostat table-form data on all 28 member states of the EU has been carried out in three different ways: 1. "Performance Positioning" of waste management unit(s) at a specific date; 2. "Performance dynamics" over a certain time period and; 3. "Performance development" expressed as a track(s). Results obtained show that the Ternary Diagram Method is very well suited to be used for better understanding of past developments and coherences, for monitoring of current situations and prognosis of future paths. One of the interesting coherences shown by the method is the linked development of recycling & composting (60-65%) with incineration (40-35%) performance over the last 20years in the EU 28.

Design, quality, and quality assurance of solid recovered fuels for the substitution of fossil feedstock in the cement industry.

This paper describes the requirements for the production, quality, and quality assurance of solid recovered fuels (SRF) that are increasingly used in the cement industry. Different aspects have to be considered before using SRF as an alternative fuel. Here, a study on the quality of SRF used in the cement industry is presented. This overview is completed by an investigation of type and properties of input materials used at waste splitting and SRF production plants in Austria. As a simplified classification, SRF can be divided into two classes: a fine, high-calorific SRF for the main burner, or coarser SRF material with low calorific value for secondary firing systems, such as precombustion chambers or similar systems. In the present study, SRFs coming from various sources that fall under these two different waste fuel classes are discussed. Both SRFs are actually fired in the grey clinker kiln of the Holcim (Slovensko) plant in Rohoznik (Slovakia). The fine premium-quality material is used in the main burner and the coarse regular-quality material is fed to a FLS Hotdisc combustion device. In general, the alternative fuels are used instead of their substituted fossil fuels. For this, chemical compositions and other properties of SRF were compared to hard coal as one of the most common conventional fuels in Europe. This approach allows to compare the heavy metal input from traditional and alternative fuels and to comment on the legal requirements on SRF that, at the moment, are under development in Europe.

Climate impact analysis of waste treatment scenarios--thermal treatment of commercial and pretreated waste versus landfilling in Austria.

A major challenge for modern waste management lies in a smart integration of waste-to-energy installations in local energy systems in such a way that the energy efficiency of the waste-to-energy plant is optimized and that the energy contained in the waste is, therefore, optimally utilized. The extent of integration of thermal waste treatment processes into regular energy supply systems plays a major role with regard to climate control. In this research, the specific waste management situation looked at scenarios aiming at maximizing the energy recovery from waste (i.e. actual scenario and waste-to-energy process with 75% energy efficiency [22.5% electricity, 52.5% heat]) yield greenhouse gas emission savings due to the fact that more greenhouse gas emissions are avoided in the energy sector than caused by the various waste treatment processes. Comparing dedicated waste-to-energy-systems based on the combined heat and power (CHP) process with concepts based on sole electricity production, the energy efficiency proves to be crucial with regard to climate control. This underlines the importance of choosing appropriate sites for waste-to-energy-plants. This research was looking at the effect with regard to the climate impact of various waste management scenarios that could be applied alternatively by a private waste management company in Austria. The research is, therefore, based on a specific set of data for the waste streams looked at (waste characteristics, logistics needed, etc.). Furthermore, the investigated scenarios have been defined based on the actual available alternatives with regard to the usage of treatment plants for this specific company. The standard scenarios for identifying climate impact implications due to energy recovery from waste are based on the respective marginal energy data for the power and heat generation facilities/industrial processes in Austria.