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NanoFlueGas : a pioneering study on nanostructured waste incineration

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INERIS, Mines Nantes and Trédi, a division of the Séché Environnement group have led, with the support of ADEME (French Environment and Energy Management Agency), the NanoFlueGas project, which is one of the first projects on the safety of nanomaterials at the end of their life cycle, particularly in the incineration sector. This exploratory work shows that the nanoparticles in certain waste materials may be released in gross emissions from furnaces after the combustion process. The first results have shown that treatment systems such as bag filters are very effective in the treatment of emissions containing  nanoparticles.

 

At the present time, there is no particular treatment of nanomaterials at the end of their life cycle. There is no branch specialised in incineration, and present flue gas treatment processes have not yet demonstrated how they deal with this particular risk. Current legislation does not in fact take into account the specificities of nanomaterials. Against this background, INERIS (National Institute for Environmental Technology and hazards), Mines Nantes and TREDI, a division of the Séché Environment group, pooled their knowledge and expertise, from 2011 to 2014, within the framework of the NanoFlueGas project.

This exploratory work is being carried out as part of the ADEME program CORTEA (Knowledge, reduction at source, and treatment of air emmissions), which focuses on questions of health and environment in its research work into air quality. Coordinated by INERIS, the  NanoFlueGas project aims to improve the processes used in treating waste, in particular in incineration, concerning the hazards linked to manufactured nanomaterials.

 

Working towards safety in the incineration sector

 

The first objective is to achieve a better understanding, through studying three types of waste, the emission mechanisms of nanofillers in the combustion process. Another objective of the project is to assess the effectiveness, concerning nanomaterials, of flue gas treatment systems used in modern waste incineration plants. This is a pioneering project in that it addresses the issue of the potential emission of nanos in conditions which are as close as possible to real life situations in waste incineration plants. NanoFlueGas has been working on two experimental pilots for carrying out trials  : a tubular furnace and a bag filtration unit with a sorbent injection system. After studying the deposits, three waste-types were selected for the study phase on combustion emissions : powder 'Carbon-based' waste, liquid 'paint-based' waste and solid 'polymer-based' waste. In all three cases, the presence of nanomaterials in the waste was confirmed and quantified using several different analytical techniques.

 

A knowledge base that paves the way for further research

 

The results from the NanoFlueGas project provide the first knowledge base on nanos at the end of their life cycle, paving the way for work on improving the recognition of nanosafety in risk management within the incineration sector. The gross emissions from the waste combustion phase were studied before treatment. In all three cases, the emission of a nanostructured aerosol was observed during the combustion process: a nano-carbon aerosol ('Carbon-based' waste) and two nano-silica aerosols (paint-based' waste and 'polymer-based' waste). Incineration does not automatically remove the nanostructured nature of waste, as some nanofillers can be transferred to the gross gaseous effluents. In the case of polymer waste, the study shows that combustion results in the emission, in the raw gas, of two distinct families of nanostructured particles: one is a product of the nano-structure initially contained in the waste, and the other produced by the combustion process. The work carried out under the NanoFlueGas project has also shown the value of bag filter units with sorbent injection systems, such as in gross emissions treatment. Under the best conditions, it would seem that this process, tested on a nano-carbon aerosol, manages to retain more than 96% in terms of the number of carbon nanoparticles emitted in gross fumes.

The effectiveness of this type of equipment is usually combined with other treatment processes on the same line of flue gas treatment. Furthermore, analysis of the cost-benefit ratio of using this system  has proved favorable in the case of units equipped for energy valorisation, according to initial estimates.

 

For more information : Dossier de presse NanoFlueGas

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