Alexia Aldrian

Monitoring of WEEE plastics in regards to brominated flame retardants using handheld XRF

This contribution is focused on the on-site determination of the bromine content in waste electrical and electronic equipment (WEEE), in particular waste plastics from television sets (TV) and personal computer monitors (PC) using a handheld X-ray fluorescence (XRF) device. The described approach allows the examination of samples in regards to the compliance with legal specifications for polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) directly after disassembling and facilitates the sorting out of plastics with high contents of brominated flame retardants (BFRs). In all, over 3000 pieces of black (TV) and 1600 pieces of grey (PC) plastic waste were analysed with handheld XRF technique for this study. Especially noticeable was the high percentage of pieces with a bromine content of over 50,000ppm for TV (7%) and PC (39%) waste plastics. The applied method was validated by comparing the data of handheld XRF with results obtained by GC-MS. The results showed the expected and sufficiently accurate correlation between these two methods. It is shown that handheld XRF technique is an effective tool for fast monitoring of large volumes of WEEE plastics in regards to BFRs for on-site measurements.

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.

Landfill mining: Resource potential of Austrian landfills – Evaluation and quality assessment of recovered municipal solid waste by chemical analyses

Since the need for raw materials in countries undergoing industrialisation (like China) is rising, the availability of metal and fossil fuel energy resources (like ores or coal) has changed in recent years. Landfill sites can contain considerable amounts of recyclables and energy-recoverable materials, therefore, landfill mining is an option for exploiting dumped secondary raw materials, saving primary sources. For the purposes of this article, two sanitary landfill sites have been chosen for obtaining actual data to determine the resource potential of Austrian landfills. To evaluate how pretreating waste before disposal affects the resource potential of landfills, the first landfill site has been selected because it has received untreated waste, whereas mechanically–biologically treated waste was dumped in the second. The scope of this investigation comprised: (1) waste characterisation by sorting analyses of recovered waste; and (2) chemical analyses of specific waste fractions for quality assessment regarding potential energy recovery by using it as solid recovered fuels. The content of eight heavy metals and the net calorific values were determined for the chemical characterisation tests.

Landfill mining: Development of a theoretical method for a preliminary estimate of the raw material potential of landfill sites.

In recent years, the rising need for raw materials by emerging economies (e.g. China) has led to a change in the availability of certain primary raw materials, such as ores or coal. The accompanying rising demand for secondary raw materials as possible substitutes for primary resources, the soaring prices and the global lack of specific (e.g. metallic) raw materials pique the interest of science and economy to consider landfills as possible secondary sources of raw materials. These sites often contain substantial amounts of materials that can be potentially utilised materially or energetically. To investigate the raw material potential of a landfill, boreholes and excavations, as well as subsequent hand sorting have proven quite successful. These procedures, however, are expensive and time consuming as they frequently require extensive construction measures on the landfill body or waste mass. For this reason, this article introduces a newly developed, affordable, theoretical method for the estimation of landfill contents. The article summarises the individual calculation steps of the method and demonstrates this using the example of a selected Austrian sanitary landfill. To assess the practicality and plausibility, the mathematically determined raw material potential is compared with the actual results from experimental studies of excavated waste from the same landfill (actual raw material potential).

Development and validation of a new direct sampling method for coarse mono- and mixed waste fractions bound in bales

ABSTRACT Sampling of coarse waste materials is considered to be a particularly challenging task and is at the same time the most crucial step in the overall data acquisition process. Despite this fact, research work on new sampling methods or new scientific approaches to sampling has been rather limited over the last decades. This paper focuses on a completely new sampling procedure for coarse two-dimensional materials similar to municipal solid waste or packaging plastics. The developed method is especially suitable for materials with particle sizes >100 mm and is based on the ‘press-and-drill method’ introduced by researchers from Fachhochschule Nordhausen. The basic idea is to sample the material in its compressed form (e.g. as bales) with a drilling tool in order to gain increments. The study presented in this paper shows the results of two extensive test series applying this new sampling technique to a middle-calorific fraction produced from packaging material (mainly plastics, textiles and paper). In parallel, the state-of-the-art approach was also applied on the same materials to gain valuable reference data. Results from both approaches are used for the extensive validation of the new sampling method. The verification of accuracy was realised by doping the material with defined pieces of foil containing molybdenum sulphide (MoS2) which acted as a tracer in the bale. The results obtained by the new direct bale sampling showed not only good accordance with the actual tracer content in each bale but also with results derived from the state-of-the-art approach. In this study, homogeneously distributed parameters (e.g. loss of ignition) were included just as inhomogeneously distributed elements (i.e. Cu). It is shown that sufficient representativeness for coarse materials (d95 > 300 mm) is obtained despite relatively small sample amounts and without previous comminution of the material.

Solid recovered fuels in the cement industry – semi-automated sample preparation unit as a means for facilitated practical application

One of the challenges for the cement industry is the quality assurance of alternative fuel (e.g. solid recovered fuel, SRF) in co-incineration plants – especially for inhomogeneous alternative fuels with large particle sizes (d95⩾100 mm), which will gain even more importance in the substitution of conventional fuels due to low production costs. Existing standards for sampling and sample preparation do not cover the challenges resulting from these kinds of materials. A possible approach to ensure quality monitoring is shown in the present contribution. For this, a specially manufactured, automated comminution and sample divider device was installed at a cement plant in Rohožnik. In order to prove its practical suitability with methods according to current standards, the sampling and sample preparation process were validated for alternative fuel with a grain size >30 mm (i.e. d95=approximately 100 mm), so-called ‘Hotdisc SRF’. Therefore, series of samples were taken and analysed. A comparison of the analysis results with the yearly average values obtained through a reference investigation route showed good accordance. Further investigations during the validation process also showed that segregation or enrichment of material throughout the comminution plant does not occur. The results also demonstrate that compliance with legal standards regarding the minimum sample amount is not sufficient for inhomogeneous and coarse particle size alternative fuels. Instead, higher sample amounts after the first particle size reduction step are strongly recommended in order to gain a representative laboratory sample.