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A new technology was recently developed for municipal solid waste incineration (MSWI) fly ash stabilization, based on the employment of all waste and byproduct materials. In particular, the proposed method is based on the use of amorphous silica contained in rice husk ash (RHA), an agricultural byproduct material (COSMOS-RICE project). The obtained final inert can be applied in several applications to produce “green composites”. In this work, for the first time, a process for pre-treatment of rice husk, before its use in the stabilization of heavy metals, based on the employment of Instant Pressure Drop technology (DIC) was tested. The aim of this work is to verify the influence of the pre-treatment on the efficiency on heavy metals stabilization in the COSMOS-RICE technology. DIC technique is based on a thermomechanical effect induced by an abrupt transition from high steam pressure to a vacuum, to produce changes in the material. Two different DIC pre-treatments were selected and thermal annealing at different temperatures were performed on rice husk. The resulting RHAs were employed to obtain COSMOS-RICE samples, and the stabilization procedure was tested on the MSWI fly ash. In the frame of this work, some thermal treatments were also realized in O2-limiting conditions, to test the effect of charcoal obtained from RHA on the stabilization procedure. The results of this work show that the application of DIC technology into existing treatment cycles of some waste materials should be investigated in more details to offer the possibility to stabilize and reuse waste.

Fly ashes from municipal waste incineration represent today an environmental problem because of their extremely fine size and the relevant quantities of heavy metals (Pb, Zn, Cd, etc.) mainly condensed on their surface. The inertisation by a vitrification process of municipal waste incineration fly ashes together with other inorganic waste such as coal combustion, fly ashes, steel dust, foundry sand, etc. can produce an inert and chemically stable glass. With this process, developed within the Waste Based Reinforced Materials project, cofinanced by the Life Environment Programme, a good quality glass has been produced. With this glass continuous fibres have been produced in a pilot bushing plant. The plastic and bituminous materials reinforced with these fibres have physical and mechanical properties comparable with those of commercial glass fibres.

Glass ®bres are well-known reinforcing agents for different kinds of materials. For example, plastics, polyesters and epoxy resins can be reinforced using glass ®bres originally developed for electrical applications; the resistance of bituminous materials is increased with the addition of chemically resistant glass ®bres, and alkali resistant ®bres are used in reinforced concrete. The price of conventional glass ®bres is high because of the cost of the raw materials and of the high energy cost involved in the melting process. Therefore, a process which would allow the substitution of the natural raw materials with secondary products such as certain inorganic industrial wastes which have a lower melting temperature, would be of interest because it could increase the saving of energy and natural resources. Moreover, the disposal of industrial wastes in land®ll would be reduced.

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