Karl Lorber

Production, quality and quality assurance of Refuse Derived Fuels (RDFs).

This contribution describes characterization, classification, production, application and quality assurance of Refuse Derived Fuels (RDFs) that are increasingly used in a wide range of co-incineration plants. It is shown in this paper, that the fuel-parameter, i.e. net calorific value [MJ/kg(OS)], particle size d(90) or d(95) [mm], impurities [w%], chlorine content [w%], sulfur content [w%], fluorine content [w%], ash content [w%], moisture [w%] and heavy metals content [mg/kg(DM)], can be preferentially used for the classification of different types of RDF applied for co-incineration and substitution of fossil-fuel in different industial sectors. Describing the external production of RDF by processing and confectioning of wastes as well as internal processing of waste at the incineration plant, a case study is reported on the application of RDF made out of different household waste fractions in a 120,000t/yr Waste to Energy (WtE) circulating fluidized bed (CFB) incinerator. For that purpose, delivered wastes, as well as incinerator feedstock material (i.e. after internal waste processing) are extensively investigated. Starting with elaboration of sampling plan in accordance with the relevant guidelines and standards, waste from different suppliers was sampled. Moreover, manual sorting analyses and chemical analyses were carried out. Finally, results of investigations are presented and discussed in the paper.

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 Rohožnik (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.

Design and quality assurance for solid recovered fuel.

This contribution describes the processing and the quality assurance of solid recovered fuel (SRF) that is increasingly used in a wide range of co-incineration plants. As an example, the preparation of municipal, commercial and industrial wastes for recovering of two different specifications of waste fuels (i.e. primary burner fuel and hot disc fuel used in cement industry) is reported and the multiple stage processing scheme used in SRF production is presented as well as the quality of SRF obtained. It will be shown, that removing of metals and sorting out of unwanted inert materials like stones, glass and concrete only after disintegration of the waste matrix during several crushing and separation steps can be carried out efficiently. In the following chapters, the quality assurance of SRF is demonstrated and described by using two different scenarios (i.e. different sizes of waste streams with different particle sizes, delivered to a cement plant by walking floor trucks). Based on CEN/TS-guidelines for SRF as well as national norms (ÖNORM), two sampling procedures and sample preparation schemes are elaborated for the scenarios and own practical experiences in quality assessment of heterogeneous waste fuels are reported. Finally, references are given on new, innovative laboratory equipment like cutting mills with attached cyclones and a mobile, hand-sized XRF-instrument for fast identification of extraneous materials removed from the laboratory sample prior to chemical analysis.

The use of volcanic soil as mineral landfill liner - I. Physicochemical characterization and comparison with zeolites

The main physicochemical characteristics of the volcanic soil of Southern Chile, with allophane as the main pedogenic mineral phase were analysed and compared with common zeolites (clinoptilolite) of the European market. The ultimate goal of this study was to test volcanic soil for the use as mineral landfill liner. The main results indicated that the clay and silt fractions together of the volcanic soil were between 38 and 54%. The buffering capacity of the volcanic soil was higher compared with the studied zeolites, whereas the cationic exchange capacity of the volcanic soil (between 5.2 and 6.5 cmol+ kg-1) is of the same order of magnitude of the studied zeolites (between 9.7 and 11.4 cmol+ kg-1). Moreover, the anionic exchange capacity of the volcanic soil was higher compared to the zeolites analysed. The hydraulic conductivity of the volcanic soil, measured in the laboratory at maximum proctor density, ranges between 5.16 × 10-9 and 6.48 × 10-9 ms-1, a range that is comparable to the value of 4.51 × 10-9 ms-1 of the studied zeolite. The Proctor densities of the volcanic soil are in a lower range (between 1.11 and 1.15 g ml-1) compared with zeolites (between 1.19 and 1.34 g ml-1). The volcanic soil physicochemical characteristics are comparable to all the requirements established in the Austrian landfill directive (DVO, 2000). Therefore, the use as mineral landfill basal sealing of the analysed volcanic soil appears reasonable, having a pollutant adsorption capacity comparable to zeolites. It is of special interest for Southern Chile, because there are no alternative mineral raw materials for basal liners of landfills.

Combined incineration of industrial wastes with in-plant residues in fluidized-bed utility boilers - decision relevant factors.

In Austria more than 50% of the high-calorific industrial residues and wastes generated are utilized for energy recovery in industrial utility boilers. This study investigated full-scale trials of combined incineration of in-plant residues with various industrial wastes. These trials were carried out in order to learn how the alternatively used fuel influences the incineration process itself as well as the quantity and quality of the various incineration products. The currently used fuel, which consisted of in-plant residues as well as externally acquired waste wood and the refuse-derived fuel (RDF) mixtures used during the full-scale trials are characterized in terms of material composition as well as chemical and physical parameters. An input–output mass balance for the incineration plant (two fluidized bed combustion units, 20 and 30 MW, respectively) has been established, based on the data collected during the full-scale incineration trials. Furthermore, pollutant concentrations in the off-gas as well as the solid incineration residue are reported. It is not only the pollutant content but also a variety of other internal as well as external factors that have to be considered if a company is to decide whether or not to thermally utilize specific waste types. Therefore a strengths and weaknesses profile for several types of waste and the specific industrial boiler is also presented.

Lessons learned for a more efficient knowledge and technology transfer to South American countries in the fields of solid waste and contaminated sites management

The present paper describes the development, performance and conclusions derived from three know-how and technology transfer projects to South American countries. The first project comprised a collaborative study by European and South American universities to find sustainable solutions for Chilean and Ecuadorian leather tanneries which had underachieving process performances. The second project consisted of investigations carried out in a Brazilian municipality to enhance its municipal solid waste management system. The final collaborative programme dealt with the initial identification, evaluation and registration of suspected contaminated sites in an industrial region of Chile. The detailed objectives, methods and procedures applied as well as the results and conclusions obtained in each of the three mentioned projects are presented, giving special attention to the organizational aspects and to the practical approach of each programme, concluding with their main advantages and disadvantages for identifying a set of qualitative and quantitative suggestions, and to establish transferable methods for future applications.

Disposal ponds and tailing dams

As a consequence of the recent environmental disaster at Kolontár, Hungary, in which a red mud disposal pond collapsed, we invited two experts, Professor Karl E. Lorber and Professor Helmut Antrekowitsch of the University of Leoben, to write a guest editorial covering this topic. This guest editorial acknowledges the relevance of mining wastes in terms of quantity as well as hazard potential, and demonstrates the importance of implementing ‘best available technology’ (BAT) and environmentally sound management of mining waste.

The use of volcanic soil as mineral landfill liner--III. Heavy metals retention capacity.

The volcanic soil of Southern Chile was tested for its heavy metal retention capacity. The maximum uptakes for CrO4 2- (CrVI), Cu2+, Zn2+ and Pb2+ were determined to be 2.74, 5.32, 5.86 and 7.44 mg g-1, respectively. At a slightly alkaline pH value (7.5), it seems that a precipitation-adsorption process was responsible for the Cu2+ and Zn2+ uptake onto volcanic soil. All the determined values are of the same order of magnitude as natural zeolites heavy metals adsorption capacities. In addition, the heavy metals diffusion model through a 1 m volcanic soil mineral liner shows breakthrough times of 21.6, 10.2 and 8.9 years, for Pb2+, Zn2+ and Cu2+, respectively, confirming the trend obtained in the adsorption isotherms. The natural volcanic soil of Southern Chile is an interesting material for possible use as landfill mineral basal sealing. It has an appropriate sealing potential (average K f value of 5.85 × 10-9 m s-1) and a heavy metals retention capacity comparable with natural zeolites. About two-thirds of the agricultural land in Chile (approximately 0.4 million km2) is derived from volcanic ash, suggesting an important soil volume for future landfill projects, that could be obtained in sufficient quantities from urban building activities.

Improving the adsorption capacity and solid structure of natural volcanic soil using a foaming-sintering process based on recycled polyethylene terephthalate (PET):

The volcanic soils of southern Chile have demonstrated a high capacity to adsorb environmental pollutants, but for an industrial application, a stable solid material is necessary. The objective of this work was to produce a stable ceramic material through a process involving volcanic soil-polyurethane foam produced with recycled polyethylene terephthalate (PET)- polyols, and further thermal treatment. The selected foam formulation with 35.4% volcanic soil (< 63 μm) seems to be the most suitable for thermal treatment, with temperature steps at 700, 850, 1000 and 1200°C. The porous ceramic material obtained has a stable solid form and an improved chlorophenols adsorption capacity (comparable to natural zeolites) that makes it suitable for advanced wastewater treatment and landfill leachate depuration.

Solid recovered fuels 2.0 – ‘what’s new?’

‘What’s new about solid recovered fuels (SRF)? Is it worthwhile to dedicate a special issue of Waste Management & Research to this topic?’ – These were questions posed to us in the course of compiling this special issue. As a starting point, it helps to refer back on the origins of using waste as a fuel (→ solid recovered fuel) to produce energy and the changes in both the needs for and methods of applying energy from waste technology. The traditional use (or more often the misuse) of garbage or household waste as domestic fuel for kitchen stoves and other house stoves for room heating was commonly practiced in all parts of the world. (Indeed, families still use waste as a fuel in many rural areas of developing countries to this day.) In Europe and other developed countries, the use of solid fuels (mainly coal and wood) for domestic heat supply is declining in favour of increased use of gas and oil as well as heat supply via district heating systems and renewable sources of energy (such as for example on-site solar energy systems or geothermal energy). These changes reduce the potential for misusing waste as solid fuel in domestic appliances for heat supply. Besides the implementation of a few incinerators for municipal solid waste (MSW) starting more than 100 years ago in Europe (aiming at mass and volume reduction of waste but not yet optimized for energy recovery from waste) an approach of large-scale recovery of fuel from waste could be observed in the late 1970s. Around 1980, the prevailing concept in waste management in Middle Europe was to implement and propagate the separate collection of recyclable waste materials and to process the left-over residual waste into scrap iron, waste-derived fuel and materials for composting. In German-speaking countries the waste-derived fuel at that time was known as ‘Brennstoff aus Müll” (BRAM) (i.e. ‘fuel from waste’). In fact, many actors thought to concurrently contribute to environmental protection and save money by producing homemade ‘bio-briquettes’ out of garbage, using simple hand-operated presses. Quite a number of industrial-scale mechanical sorting and separating plants for production of BRAM (e.g. the RINTER plant in Vienna/Austria or the Byker plant in the UK) and other waste fuels started their operations in the early 1980s, but all of them ultimately failed and disappeared from the market. [The situation at that time is thoroughly described in: Brennstoff aus Müll (ThoméKozmiensky, K.J. (ed.)), which was published in 1984, (ISBN 3-924511-00-4)]. Looking back from the present state of the art in modern waste management technologies, the main reasons for failure of the early BRAM-concept become evident. Unrealistic expectations