J. Van Caneghem

Automotive shredder residue (ASR): Reviewing its production from end-of-life vehicles (ELVs) and its recycling, energy or chemicals’ valorisation

ASR is in Europe classified as hazardous waste. Both the stringent landfill legislation and the objectives/legislation related to ELV treatment of various countries, will limit current landfilling practice and impose an increased efficiency of the recovery and recycling of ELVs. The present paper situates ASR within the ELV context. Primary recovery techniques recycle up to 75% of the ELV components; the remaining 25% is called ASR. Characteristics of ASR and possible upgrading by secondary recovery techniques are reviewed. The latter techniques can produce a fuel- or fillergrade ASR, however with limitations as discussed. A further reduction of ASR to be disposed of calls upon (co-)incineration or the use of thermo-chemical processes, such as pyrolysis or gasification. The application in waste-to-energy plants, in cement kilns or in metallurgical processes is possible, with attention to the possible environmental impact: research into these impacts is discussed in detail. Pyrolysis and gasification are emerging technologies: although the sole use of ASR is debatable, its mixing with other waste streams is gradually being applied in commercial processes. The environmental impacts of the processes are acceptable, but more supporting data are needed and the advantage over (co-)incineration remains to be proven.

Mass balance for POPs in hazardous and municipal solid waste incinerators

The amount of different persistent organic pollutants (POPs) in the input of waste incinerators was compared to that in the output. Three cases were considered: a rotary kiln incinerating hazardous waste, a grate furnace incinerating municipal solid waste (MSW) and the same grate furnace co-incinerating plastics of waste of electrical and electronic equipment (WEEE) and automotive shredder residue (ASR) with MSW. The mass balance for PCBs in the rotary kiln indicates that these POPs are destroyed effectively during incineration. The grate furnace can be a sink or source of PCDD/Fs and PCBs depending on the concentrations in the incinerated waste. In order to compare the total amount of POPs in input and output, a methodology was developed whereby the amount of POPs was weighed according to minimal risk doses (MRDs) or cancer potency factors. For both incinerators the PCDD/Fs, PCBs and polyaromatic hydrocarbons (PAHs) are the main contributors to total weighed POP output. In MSW, the PCDD/Fs, PBDD/Fs and polybrominated diphenylethers (PBDEs) are the main contributors to the weighed POP input. The ratios of the weighed POP-input over -output clearly indicate that the rotary kiln incinerating hazardous waste is a weighed POP sink. The grate furnace incinerating MSW is a weighed POP sink or source depending on the POP-concentrations in the waste, but the difference between output and input is rather limited. When e.g. ASR and plastics of WEEE, containing high concentrations of PBDEs and PCBs, are co-incinerated in the grate furnace, it is clearly a weighed POP sink.

Optimising energy recovery and use of chemicals, resources and materials in modern waste-to-energy plants

Due to ongoing developments in the EU waste policy, Waste-to-Energy (WtE) plants are to be optimized beyond current acceptance levels. In this paper, a non-exhaustive overview of advanced technical improvements is presented and illustrated with facts and figures from state-of-the-art combustion plants for municipal solid waste (MSW). Some of the data included originate from regular WtE plant operation - before and after optimisation - as well as from defined plant-scale research. Aspects of energy efficiency and (re-)use of chemicals, resources and materials are discussed and support, in light of best available techniques (BAT), the idea that WtE plant performance still can be improved significantly, without direct need for expensive techniques, tools or re-design. In first instance, diagnostic skills and a thorough understanding of processes and operations allow for reclaiming the silent optimisation potential.

Assessment of the impact on human health of industrial emissions to air: does the result depend on the applied method?

The impact on human health of substances emitted to air by the Flemish industry was calculated with characterization factors (CFs) provided by the CML, Eco-indicator 99, EPS, EDIP and USEtox impact assessment methods. A comparison of the results pointed out that the choice of the CFs can greatly influence conclusions on the trend of the impact over time and on the relative contribution of the individual substances. If the impact on human health of organic substances and heavy metals was assessed separately, the differences between methods were less pronounced. In this case, the impacts on human health obtained by simply dividing the emitted masses of substances by the respective minimal risk concentrations or minimal risk doses, were comparable to those calculated with the CFs of the model-based methods.

Characterisation of polycyclic aromatic hydrocarbons in flue gas and residues of a full scale fluidized bed combustor combusting non-hazardous industrial waste

This paper studies the fate of PAHs in full scale incinerators by analysing the concentration of the 16 EPA-PAHs in both the input waste and all the outputs of a full scale Fluidized Bed Combustor (FBC). Of the analysed waste inputs i.e. Waste Water Treatment (WWT) sludge, Refuse Derived Fuel (RDF) and Automotive Shredder Residue (ASR), RDF and ASR were the main PAH sources, with phenanthrene, fluoranthene and pyrene being the most important PAHs. In the flue gas sampled at the stack, naphthalene was the only predominant PAH, indicating that the PAHs in FBCs combustion gas were newly formed and did not remain from the input waste. Of the other outputs, the boiler and fly ash contained no detectable levels of PAHs, whereas the flue gas cleaning residue contained only low concentrations of naphthalene, probably adsorbed from the flue gas. The PAH fingerprint of the bottom ash corresponded rather well to the PAH fingerprint of the RDF and ASR, indicating that the PAHs in this output, in contrast to the other outputs, were mainly remainders from the PAHs in the waste inputs. A PAH mass balance showed that the total PAH input/output ratio of the FBC ranged from about 100 to about 2600 depending on the waste input composition and the obtained combustion conditions. In all cases, the FBC was clearly a net PAH sink.

Waste-to-energy: Coupling Waste Treatment to Highly Efficient CHP

Abstract Municipal Solid Waste Incineration (MSWI) has become the most widespread Best Available Technology (BAT) to treat residual waste streams in a reliable and safe way. As such, MSWI has contributed to achieve the landfill diversion targets in many EU member states. Modern waste incinerators, also referred to as Waste-to-Energy (WtE) plants, have furthermore evolved to producers of electricity, heat and steam for energy-consuming industries, agriculture and residences. However, due to the specific composition and properties of MSW and similar waste, and due to the historical development of MSWI, the exploitation of WtE plants as combined heat and power (CHP) plants is not straightforward. The aims of this paper are to develop a better understanding of these limitations, to point out possibilities for increasing the level of energy recovery and utilization in WtE plants, and to document this approach with data and experiences from selected WtE plants currently integrated in CHP schemes. Finally, some design and operational challenges for waste-fired CHP plants are further elaborated from a WtE plant supplier’s perspective.

Sustainable Waste Processing In A Grate Furnace And In A Fluidized Bed Incinerator: WtE, Recycling And Environmental Concerns

The Indaver integrated grate furnace, incinerating municipal solid waste (MSW) along with comparable industrial waste, is described. In the installation, energy is recovered by producing steam which is delivered to other companies, or used to generate electricity. The bottom ashes are wet-washed; ferrous and non-ferrous metals and granulates are recovered. Next to the grate furnace, a fluidized bed combustor (FBC) operated by SLECO is situated. It can co-incinerate various types of industrial wastes (including ASR), RDF, waste water treatment (WWT) sludges, etc. and produces steam to generate electricity. The bottom ashes are recovered as secondary raw material. It is demonstrated that both installations have a good environmental performance and address many aspects of cleaner production. This way, both grate furnace and FBC may play an important role in sustainable waste management. Depending on the fractions of the energy carrier(s), the actual energy recovery varies from 41% for the grate furnace (steam + electricity) to 27% for the FBC (only electricity). The most important airborne emissions and solid residues are monitored in both installation and are discussed in detail. For all components of interest, emissions remain well below Flemish limit values. Moreover, it was shown that both installations act as a POP sink when flue gas emissions are taken into account as a POP output. From the bottom ashes of both incinerators ferrous and non-ferrous metals and granulates are recovered, representing 19.9 and 9.2 wt% of the original waste input of respectively the grate furnace and the FBC. When introducing higher amounts of heavy metals into the FBC, co-incinerating ASR, the bottom ashes still fulfil Flemish requirements for use as secondary raw material.