Vitrification and reuse of bottom ashes from municipal solid waste incinerator MSWI

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Vitrification and reuse of bottom ashes from
municipal solid waste incinerator (MSWI)

• M.Salvo1, A.Ventrella1, M. Bassani2, E.
  Santagata2, M.Ferraris1
• 1Department of Materials Science and Chemical
  Engineering, Politecnico di Torino, Turin, Italy.
  Tel. [phone] fax [phone]
• 2Department of Hydraulics, Transportation and
  Civil Infrastructures, Politecnico di Torino,
  Turin, Italy

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Example of waste management in Italy MWSI
ASHES
Ref. http//www.trm.to.it/
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Bottom ashes land-fillingCons

• Ashes must be processed (inertisation) before
  land-filling or re-use to avoid leaching of heavy
  metal ions
• Gas emission (H2)
• Powder emission (containing chlorides, sulphates
  and heavy metals)
• Local temperature increasing (up to 90C,
  exothermic reactions)
• Shorter landfill lifetime

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Why not use bottom ashes?
Road embankments, unbound foundations, bituminous
mixture, raw material for cement
About 100 The Netherlands, 50 Germany, 50
France
Raw material in cement production
ItaIy ?
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Why not use bottom ashes?

• Advantages
• Reduction of landfill-related problems
• Save primary (not-recycled) building materials
  (sand, gravel, )

• Cons
• Leaching bottom ashes dont comply with emission
  limit values for Mo, Cu and Sb (Van Gerven et
  al., 2005).
• Bottom ashes are classified as ecotoxic
  materials. (Lapa et al., 2002)
• Inertisation treatment before use
• Intrinsic compositional heterogeneity
• Gas production in concrete
• Swelling and unknown long-term leaching in
  bituminous mixtures

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Vitrification of MSWI ashes

• Advantages
• Inertisation of enviromental harmful elements
• Volume reduction
• Homogeneous material
• Reuse

• Cons
• Cost? It will depend on its market value

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Waste vitrification in the world

• Some examples
• Japan melting (vitrification) is a widely
  accepted technology that involves the conversion
  of the waste into more stable and homogeneous
  silicate glass products through thermal treatment
  of MSW-derived materials
• USA pilot plant (VIT Inc., Vortec Corporation,)
• EU Ash melting unit (Europlasma,
  Bordeaux-France)

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Vitrification and reuse of bottom ashes at POLITO
2 tons of glass obtained by the VC MSWI bottom
ash vitrification (1400C)
Filler and aggregate in bituminous mixture
Filler and aggregate in concrete
monica.ferraris_at_polito.it
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Vitrified bottom ash composition
Cl- 0.015 wt
Chemical analysis (oxide contents in wt ) of the
glass obtained by bottom ash vitrification (MSWI
in Vercelli)
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Vitrified Bottom Ashes (VBA) in mortars and
concretes
Mechanical strength
water cement
sand aggregate coarse aggregate
glass lt5 mm
PORTLAND Type I 42,5 R or glass as filler
(lt50 and lt90 mm)
glass 5-10 mm
glass10-20 mm
Concrete
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VBA in mortars and concretes

• No alkali-silica reactions or other detrimental
  reactions were observed after 2 years in VBA
  containing concrete
• Pozzolanic activity positive test

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Compressive strength
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Compressive strength

• VBA can be used as filler (lt50 µm or lt90 µm )
  instead of cement, at least up to 20 wt.

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Compressive strength

• VBA can not be used to substitute natural sand
  (lt5mm) unless low strength applications are
  required it can not act as reinforcing second
  phase in compression because of the poor cohesion
  between the smooth surface glass sand (large
  surface area) and the cement paste.

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Compressive strength
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Compressive strength

• VBA can substitute gravel (5-10 mm 10-20 mm) up
  to 50-75 vol. VBA of this size fully exploit
  their reinforcing role as a second phase in
  concrete.

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VBA in bituminous mixtures


VBA as filler and sand
(c) (d)
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VBA in bituminous mixtures

• TESTS
• Workability and compaction (k, C1)
• Volumetric characteristic (A, v, VMA, VFA)
• Mechanical properties (E20C, ITR, Nf, etot,
  erec, S3600)

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VBA in bituminous mixtures
Bitumen absorption of the bituminous mixtures

• VBA exibit a negligible absorption of the binder
  ? significantly smaller quantity of bitumen can
  be used ? economical and environmentally
  attractive.

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VBA in bituminous mixturesMechanical properties

• Mechanical properties comparable to the reference
  mixtures (Ss 0)
• Appropriate mix design may lead to a further
  enhancement of mechanical performance

Indirect tensile strength of the bituminous
mixtures
Elastic stiffness of the bituminous mixtures
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VBA in concretes and bituminous mixtures-
CONCLUSIONS

• VBA can be used as filler, sand and aggregate in
  concretes or bituminuos mixtures, saving several
  million tons per year of natural materials and
  dramatically reducing landfill-related problems

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• Thank you!
• Contact milena.salvo_at_polito.it