Advanced waste-splitting by sensor based sorting on

File: P 218

Advanced Waste-Splitting by Sensor Based Sorting on the Example of the MT-Plant Oberlaa S. Pieber & M. Meirhofer

R. Pomberger & A. Curtis

Bioenergy 2020+ GmbH, Pinkafeld, Austria

Saubermacher Dienstleistungs AG, Graz, Austria

A.-M. Ragossnig & L. Brooks

ABSTRACT: Heterogeneous wastes, which cannot be material-recycled easily are used for energetic utilization. Certain quality criteria need to be met in this context, addressing especially the chlorine content due to the product quality as well as to environmental and safety issues. In regard of current issues in climate policy concerning emission trading, also an increased biogenic content in these waste fractions is desirable. Therefore, experiments with a sensor-based sorting technology at pilot scale as well as large scale have been conducted to analyse the technical feasibility of this technology for its application on heterogeneous wastes to gain products with desired material and quality criteria. The results of pilot scale experiments show that the sensor-based sorting technology is generally technically feasible to gain waste fractions with the required characteristics, if the technology was adjusted to the specific waste stream. Due to restrictions during the large scale experiment a number of further issues need to be addressed in further experiments to allow for a concluding evaluation of that treatment concept.

1 INTRODUCTION AND RELEVANCE Waste management is playing a significant role in efforts to combat the anthropogenic climate change and environmental pollution and is therefore continuously changing from land filling to other options, such as material reuse and recycling all over the world. If waste will be used as a substitution for primary resources, it has to be processed to meet the required material or quality criteria. Sensor-based sorting is a state-of-the-art technology for the treatment of separately collected recyclables, such as plastic, paper and glass, in order to secure the compliance with given quality standards. A further option, especially for heterogeneous wastes which cannot be material-recycled is the energetic utilization. High calorific components are split from the waste stream and used as a substitute for fossil fuels (so-called “refuse derived fuel” (RDF) resp. “waste derived fuel” (Rotter et al. 2010)) in certain industry sectors (e.g. cement industry or pulp & paper industry). Hence, waste material can be used as (partly) renewable energy source if it meets certain quality criteria in order to secure that environmental standards as well as product quality are not being compromised and process conditions are not being affected negatively (Ragossnig & Lorber 2005), e.g. the content of chlorine compounds has to be limited. In order to increase the future marketing opportunities, separating biogenic (i.e. mainly paper, cardboard and wooden materials) from non-biogenic, i.e. fossil materials is additionally relevant as the biogenic content might gain an important role due to the CO 2 emission trading in the near future. Processing of heterogeneous wastes to meet these required criteria is therefore crucial. However, although sensor-based sorting technologies are already available for the processing of homogeneous wastes, they are not yet widely applied for the sorting of heterogeneous wastes. Therefore, the evaluation of the technical feasibility of the application of sensor-based sorting technologies on heterogeneous waste streams is focused in the research underlying this conference contribution. Experiments at pilot and large scale were conducted in order to prove whether this technology could be used to gain waste fractions with the required characteristics.

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Fachhochschulstudiengänge Burgenland GmbH, Pinkafeld, Austria

2 MATERIAL AND METHODS A near infrared (NIR) system was used at pilot and large scale. Two specific waste streams from a mechanical treatment plant, processing 60,000 tons commercial solid waste per year, were analyzed and characterized regarding their composition: a high calorific (HC, particle size > 120 mm) and a medium calorific stream (MC, particle size 20 – 120 mm). Both waste streams are destined for the utilization as RDF in the cement industry. The composition of the streams is shown in Fig. 1. Sorting Campaign (HC: n=7; MC: n=2)

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1 Undefined Organic 2 Wood 3 Paper & Cardboard 4 Polymers 5 Dark Polymers 6 Textiles 7 Metals 8 Hazardous Wastes 9 Inert Waste 10 Other Waste Fractions 11Compound Materials 12 Fine Fraction particle size < 80 – 100 mm for HC < 30 – 60 mm for MC

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Fig. 1: Characterization of the test material: a) High Calorific Waste Stream (HC); b) Medium Calorific Waste Stream (MC); TR = Test Run. Sorted material in total [kg]: Sorting campaign: HC 340, MC 110; Pilot TR1: HC 60, MC 60; Pilot TR2&3: HC 120, MC 140; Large TR: HC 290, MC 340

Experiments were targeted towards (a) the removal of contaminants (chlorine compounds) followed by (b) the separation of biogenic from non-biogenic, i.e. fossil materials. Therefore the sensor system was tuned to firstly reject polymers containing polyvinyl chloride (PVC) and secondly remove biogenic materials from this PVC-freed material, resulting in three outputstreams: (R1) Reject 1: PVC output; (R2) Reject 2: biogenic output to be used as RDF; (P2) Passing 2: fossil output also to be used as RDF. To optimize the quantitative reject of PVCcontaining materials (R1) and the quality and quantity of the biogenic reject (R2) in the outcome of HC and MC, parameter configurations (a.o. scanning speed of the sensor-system, pressure of compressed air, sieving of the material, etc.) were varied. Based on these results at pilot scale, a test run at large scale was conducted. This experiment should allow for getting first results although the existing plant was optimized for a different type of waste stream and a different sorting task. The yield (R2) and the purity (R2, P2) were used for the evaluation of the separation of biogenic from fossil materials. The yield represents the rejected mass-proportion of material that is supposed to be rejected. The purity is the mass-proportion of material sorted correctly into R2 or P2. The fine fraction (for particle size see Fig. 1) was excluded from this evaluation and textiles were assumed to be biogenic if found in R2 and assumed to be fossil if found in P2. The rejection of PVC-containing materials was analyzed by chemical quantification of chlorine content (pilot- and large scale tests). 3 RESULTS AND DISCUSSION For the HC waste stream, an optimized parameter configuration of the pressure of compressed air and an appropriate NIR identification scheme were found in the pilot scale test run (TR) no. 2 for the assigned problem. Concerning the biogenic reject a yield of about 88% and purity of about 96% for a mass-fraction of around 21% was achieved (Fig. 2a and 2b). The remaining 696

material (approx. 74%, P2) had a purity of around 88%. When testing these parameters at large scale, a lower purity for of the biogenic reject (R2) (Fig. 2c, Tab. 1) as well as the remaining material (P2) compared to the pilot scale tests was achieved. Furthermore, the yield and massfraction (Fig. 2d) of R2 were significantly decreased – a result of the plant being designed and optimized for a different waste stream and a different sorting task. a)

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Fig. 2: Processing experiments of the HC waste stream. Data (wt%) are gained from about 60 kg (pilot TRs) and 290 kg (large) of original substance manually sorted in total. a) Comparison of the pilot scale test runs 1 – 3 in regard of gained mass fractions, purity and yield; b) mass flow of waste material at pilot scale test run 2; c) Composition of output streams at large scale, for 1 – 12 see Fig. 1; d) mass flow of waste material at large scale

First results (Tab. 1) of distinct chemical characterization of the output-fractions of the HC as well as the MC waste stream in regard of their characteristics as RDF (e.g. chlorine content and lower heating value (LHV) indicate that the separation of the PVC-containing materials results in very much decreased chlorine content in R2 as well as P2 (compare Tab. 1). Furthermore a slightly decreased heating value is achieved in the R2 (due to the increased biogenic content) and an increased heating value in P2. A broad evaluation is in progress. Tab. 1: Comparison of pilot scale (test run 2) and large scale (mean-values[n]) HC, Pilot, TR2 HC, Large MC, Pilot, TR2 MC, Large Sorted, total kg OS1 approx. 60 approx. 290 approx. 80 approx. 340 Yield R2/Massfraction R1 wt% OS1 88.1[3]/5.1[3] 20.2/3.4 79.4[3]/5.0[3] 16.7/2.7 [3] [4] Purity/Mass fraction R2 wt% OS 96.1/21.1 79.1/6.2 84.4/28.0[3] 87.4/5.0[3] Purity/Mass fraction P2 wt% OS 88.1/73.8[3] 72.7/71.2[4] 95.3/67.1[3] 57.8/51.8[3] 2 Cl in Material/R2/P2 wt% DM 4.5/0.3/0.4 n.a. 2.1/0.3/1.0 n.a. LHV Material/R2/P2 MJ/kg OS 23.3/13.5/31.3 n.a. 15.6/11.5/16.4 n.a. 1 OS = Original substance (wet, incl. inerts, etc.); 2Dried Material (excl. inerts, etc.); Cl = Chlorine, LHV = Lower Heating Value; n.a. = not yet analysed; R1 = Reject 1 (PVC-containing); R2 = Reject 2 (biogenic); P2 = Passing 2 (fossil); HC/MC = High/Medium Calorific Waste Stream

Concerning the manual characterization of the MC waste stream, results similar to the HC waste stream were achieved. However, yield (approx. 80%) and purity (approx. 84%) of the biogenic reject (R2) at pilot scale were lower compared to the HC waste stream; the purity of P2 was increased instead to about 95%. Comparing the first results at large scale to the pilot scale results, the purity of R2 (approx. 87%) was slightly increased, whereas the purity of P2 was 697

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largely decreased (approx. 58%). However, only a low yield (approx. 18%) was achieved similar to the high calorific waste stream. b)

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Fig. 3: Processing experiments of the MC waste stream. Data (wt%) are gained from about 60 – 80 kg (pilot) and 340 kg (large) of original substance manually sorted in total. a) – d) as in Fig. 2

4 CONCLUSIONS AND PERSPECTIVES The results of pilot scale tests showed that the sensor-based sorting technology is generally feasible to gain waste fractions with the required characteristics (especially concerning the chlorine content of the waste stream) if the sensor systems are adjusted to the specific waste stream. This is especially shown by the chlorine content, purity and yield at pilot-scale. First results at large scale indicate that additional issues need to be addressed to gain similar results. The challenges to be taken are related to the overall plant concept. Further experiments in large scale are planned, in order to solve the additional construction issues to adapt a large scale MT-plant for processing of the presented waste streams by sensor-based sorting to gain output fractions with the desired characteristics. ACKNOWLEDGEMENTS This research within the K1-centre “BIOENERGY 2020+” was promoted by the COMET funding scheme executed by the Austrian Research Promotion Agency and financed by national Austrian funds as well as funds from the provinces of Burgenland, Lower Austria and Styria. The co-financing from industry to be provided within the COMET funding scheme was granted by Umweltdienst Burgenland GmbH, Saubermacher Dienstleistungs AG, Komptech Research Center GmbH and BT Wolfgang Binder GmbH. REFERENCES Ragossnig, A. & Lorber, K.E. (2005) Combined incineration of industrial wastes with in-plant residues in fluidized-bed utility boilers – decision relevant factors. In: Waste Management & Research, Volume 23/5, Copenhagen. Rotter, V.S., Lehmann, A., Marzi, T., Möhle, E., Schignitz, D. & Hoffman G. (2010) New techniques for the characterization of refuse-derived fuels and solid recovered fuels. In: Waste Management & Research, Copenhagen, doi:10.1177/0734242X10364210.

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