Page 65 - European Energy Innovation - spring 2019 publication
P. 65
Spring 2019 European Energy Innovation 65
ENERGY FROM WASTE
While it is true that mixed waste is the non-ferrous stream, which is
the dirtiest (and most difficult to dominated by aluminium and copper,
process) type of solid fuel, this has has proven to be rich in precious
prompted a huge effort in improving metals such as silver and gold, that
the performances of flue gas cleaning concentrate in the fine fraction. Also
and of combustion optimization. the inert components of bottom
ash can be used in civil engineering
Emission limits at the stack of WTE application, as well as in the
plants are not only extremely strict cement and concrete industry. More
when compared to other industrial complicated is the recovery from
sectors, but also strictly controlled fly ash, but some possibilities are
and generally publicly available on the envisaged especially for Zinc. In any
real time. While the “dioxin issue” has case such (minor) flow of material
been tackled back in 1997, by cutting is the one where toxic elements are
the emission limits by about 800 concentrated, which means it is the
times, a more recent considerable “final sink” needed to safely isolate
effort has been put in decreasing them from the environment.
NOx and HCl emissions well below
the EU emission limits, and the new A last and more mature point of
targets widely discussed and recently discussion regarding WTE plants is
set by the revision of the BREF on their lack of flexibility, i.e. the fact that
waste incineration are putting further they will represent a “rigid” element
pressure to the plants designers and in the whole waste treatment chain,
operators. Also the emission of fine that on the contrary has to be
dust has been targeted, especially flexible in order to accommodate
in Italy, where a campaign on the the envisaged increases of source
risk of nanoparticle emissions by separation, as well as the waste
incineration plants had mounted and prevention policies. This is probably
generated widespread concern. the most robust claim, which has to
be seriously targeted with a proper
A comprehensive research carried design of the treatment capacity of
out by the LEAP Laboratory and new plants, taking into account that
Politecnico di Milano has then more source separation will generate
showed the effectiveness of fabric more sorting and recycling residues
filters in capturing also very fine dust, that should be routed to energy
with typical measured stack number recovery. Avoiding any construction
concentration being of the same of new plants where there is a lack of
order of magnitude (or sometimes capacity simply means to guarantee
even lower) of the baseline presence a long and prosperous life to landfills
in ambient air. and/or huge and easy earnings to
the waste transport sector. At the
Following the acknowledgment detriment of the environment. l
of such progresses in controlling
the stack emissions, a second Mario Grosso is an environmental engineer graduated at Politecnico di
point of discussion is targeting the Milano. He holds a PhD on the topic of dioxin formation and destruction
solid residues generated by the in waste incineration plants. He is currently Associate Professor at the
incineration process, i.e. bottom ash, Department of Civil and Environmental Engineering of Politecnico.
fly ash and flue gas cleaning residues.
Again, in recent years a lot of efforts He coordinates the AWARE (Assessment on WAste and REsources)
have been put by the operators in research group, aimed at researching on waste prevention, technologies
achieving high levels of material for recovery and disposal of solid waste and of residues, integrated
recovery especially from bottom waste management, flue gas treatment technologies for industrial plants,
ash, where ferrous and non-ferrous definition of scenarios for emission reduction, as well as Life Cycle
metals are present in interesting Assessment (LCA).
amount and can be easily extracted
and sent to recycling. Especially
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