THERMAL PROCESSES

- Feedstock recycling
- Energy Recovery

Feedstock Recycling

While, in principle, feedstock recycling has great potential to boost plastics waste recovery levels, in practice, economic considerations as well as the availability of a constant quality and quantity of plastics waste are key to its viability. This depends heavily on the local situation. A variant of feedstock recycling is the use of plastics as a chemical reductant necessary for the recovery of non-ferrous metals. Here the plastics not only react with the metals, but are also used for their energy value.

As an example, the Japanese Plastic Waste Management Institute (PWMI) has developed a zero emission chemical recycle technology. Waste plastics out of car, E&E products are used for electricity generation by gasification and bromine is recovered at the same time.

Studies of interest:

• “Implementation of Thermal Processes for Feedstock Recycling of Bromine and Antimony, with Energy recovery, from Plastics Waste of Electrical and Electronic Equipment, Phase 1” Dr H. Boerrigter, Netherlands Energy Research Foundation (ECN), July 2000.
  
  
  • Evaluation and ranking of various available processes for Feedstock Recycling of plastics Waste from Electrical and Electronic Equipment (WEEE), containing brominated flame-retardants (BFRs) –including Deca-BDE-, with the aim of recycling bromine and recovering the energy content. The report concluded that staged-gasification is a thermal process that is potentially suitable for this purpose. In addition no increase of dioxin/furans was observed.
    
    
• “Recovery of bromine and energy from waste electrical and electronic equipment containing bromine in the European Union”. May 1999, PB Kennedy & Donkin Limited.
  
  
  • A study carried out to evaluate the economical impact of bromine recovery from WEEE plastics –including Deca-BDE-. The report concluded that an installation handling WEEE plastics containing bromine can operate profitably when recovering amounts above 500 tons/year.

Energy recovery

Energy recovery is a key recovery option for plastics, as their basic raw material, is derived from oil. While in the past, there has been much opposition - some justified by concerns around the poor environmental performance of old incinerators - today energy recovery is more widely approved as an environmentally sound option. Emission levels from incinerators have been significantly reduced and waste combustion for the recovery of energy is embodied in European legislation. As well as municipal incineration with energy recovery, potential also exists as an alternative fuel in other processes. Energy recovery alongside material recycling has a vital role to play in diverting plastic waste from landfill and maximizing environmental gain.

Incineration

Incineration tests, pyrolysis and combustion studies have demonstrated that waste from E&E equipment can be safely added to today's municipal solid waste (MSW) to generate in an environmentally sound manner useful energy when incinerating BFR-containing materials. PBDD/F formation is not altered by the presence of the bromine-containing waste, and remains well within emission standards in these processes. The OECD came to the same conclusion regarding the insignificance of dioxin/furan formation when incinerating BFRs. The OECD noted that the highest formation rates for brominated dioxins/furans from PBDEs during laboratory experiments were associated with low temperatures and pyrolitic conditions. Modern waste-to-energy facilities are specifically designed to avoid these conditions. A report from the European Commission came to the same conclusions.

BSEF has cooperated with Forschungszentrum Karlsruhe and various industry partners under the umbrella of the PlasticsEurope to undertake a number of research programs. The aim of these was to investigate the co-combustion of plastic waste streams together with municipal solid waste. Plastics containing brominated flame retardants were fed to the pilot plant, TAMARA, with 250 kg/h feed to simulate full scale incinerators. Different plastics such as those used in TV monitors and printed wiring boards were used as starting material. In one of these tests, in which the Br content of the fuel was increased to approximately 10 g/kg dry waste, results confirmed that up until a level of 3 g, no detectable amounts of elementary Br2 could be detected in the raw gas, post- incineration.

State of the art thermal processes are a dioxin sink. The example of the TAMARA study showed that > 98% of the brominated dioxins and furans had been destroyed during the controlled combustion process of WEEE.

Smelters

Innovative approaches to recycling plastics are now used which have significant economic benefits in terms of reducing waste management costs. To produce copper from recycled material rather than from ore, means that only one-sixth of the energy is needed. Waste from the E&E sector can now be used as a feed stream in non-ferrous metal smelting plants.

As an example of this process, the Swedish company Boliden, has developed a recycling process for electrical and electronic equipment waste, in compliance with European regulation, whereby the metals are recovered. The plastics provide energy for the smelting process. BFR containing plastics have been tested in this process and fully meet the smelter's requirements. Currently, the flame retardant industry (EFRA) is running a trial, at UMICORE smelter in Belgium, with 250 tonnes of WEEE plastics to demonstrate the economic viability and environmentally friendly character of this practical solution.

Also, an eco efficiency study carried out by Plastics Europe shows that metal smelter provides the highest recovery rate for handling mobile phones, without high dismantling costs.

Metal smelters recycling in Europe

Cement and Steel Industries

Section under development

Landfill disposal

Studies of interest:

• “TV case study, a life cycle analysis”’, SP TV LCA data. Simonson, M., Blomqvist, P., Boldizar, A., Moeller, K., Rosell, L., Tullin, C., Stripple, H., Sundqvist, J.O. Fire-LCA model, Interscience Communication Ltd., London, ISBN 91-7848-811-7. 2000.
  
  
  • This study estimated no significant emissions from Deca-BDE into the environment. WEEE plastics coming into landfill do not cause leaching of BFRs or only in such minimal quantities that they are of no significance.



• “Risk Assessment of Decabromodiphenylether, Deca-BDE”, CAS Number: 1163-19-5, Final Environmental Draft of May 2004, pages 26-27
  (http://ecb.jrc.it/esis/esis.php?PGM=ora&DEPUIS=autre)



• The EU Risk Assessment on DecaBDE includes a whole section on End-of-life (EoL) and on dioxins and furans. The EoL sections looks into the various disposal and recovery options including recycling, recovery and landfill. In none of the sections mentioned above significant risks were identified. On landfill, the risk assessment report indicates: “When decabromodiphenyl ether in plastics is disposed of to landfill, in theory it could leach out of the plastic and into groundwater or volatilise to the atmosphere. However, several experiments have shown that leaching of decabromodiphenyl ether from polymers is minimal and it would not be expected to leach to a significant extent from polymers in landfill, unless the polymer itself undergoes some form of degradation, thus releasing the decabromodiphenyl ether. Any released decabromodiphenyl ether is likely to adsorb strongly onto soil, thus minimising the possibility of reaching groundwater. Similarly, the low vapour pressure of the substance would limit its volatility to the atmosphere.”

For more information read the paper on “WEEE plastics with brominated flame retardants – from legislation to separate treatment”.

Studies of interest:

• “Electrical and electronic plastics waste co-combustion with municipal solid waste for energy recovery”, Juergen Vehlow, Forschungszentrum Karlsruhe, Mark, Dow Europe, February 1997
  
  
• “Recycling of bromine from plastics containing brominated flame retardants in state-of the-art combustion facilities”, Tamara, Vehlow, B. Forschungszentrum Karlsruhe Institut für Technische Chemie Bereich Thermische Abfallbehandlung, Plastics Europe, EBFRIP, 2002.
  
  
  • Both pilot studies (carried out by German institute FZK and Plastics Europe) show that brominated flame retardant –including Deca-BDE- contained in WEEE plastics can be safely handled in modern household waste incinerators. The study has concluded that up to 3% WEEE plastics containing BFRs can be safely added to the incinerator. The halogens have a positive cleaning effect on the heavy metals in the slag.
    
    
• “Emission measurements during incineration of waste containing brominated flame retardants” by Dag Borgnes, Bente Rikheim. 2004.
  
  
  • Three full scale trials adding 10% waste containing brominated flame retardants –including Deca-BDE- to a modern household waste incinerator were carried out in Norway. The report observed no increase of dioxin/furans. It even reported a decrease of dioxin/furans due to the better burn out of the waste due to the presence of these plastics.
    
    
• “Report on Incineration of Products containing Brominated Flame Retardants” OECD Waste Management Policy Group, Environment Policy Committee, ENV/EPOC/WMP(97)4/REV3, August 1998.
  
  
  • According to the International Programme on Chemical Safety (IPCS), properly controlled incineration of materials containing BFRs does not lead to the emission of significant quantities of brominated dioxins and furans. Incineration should only be carried out in properly constituted incinerators, running at consistently optimal conditions.
    
    
• “E&HS aspects on metal recovery from electronic scrap”. Sweden, Metal and Energy Recovery Conference. Lehner T., Boliden (2003).
  
  
  • The study concludes that plastics containing Deca-BDE demonstrate good energy recovery and are fully compatible with metal recycling.
    
    
• “Risk Assessment of Decabromodiphenylether, Deca-BDE”, CAS Number: 1163-19-5, Final Environmental Draft of May 2004, pages 26 and 17-18. (http://ecb.jrc.it/esis/esis.php?PGM=ora&DEPUIS=autre)
  
  
  • The EU Risk Assessment on DecaBDE includes a whole section on End-of-life (EoL) and on dioxins and furans. The EoL sections looks into the various disposal and recovery options including recycling, recovery and landfill. In none of the sections mentioned above were significant risks identified. On incineration, the risk assessment report indicates“ (…) It is expected that emissions from controlled incineration processes will be near zero (…)”