Research & development methodology for recycling residues as building materials--a proposal

Transforming Municipal Solid Waste into Construction Materials

Rapid urbanisation and the associated infrastructure development are creating a deficit of conventional construction materials and straining the natural resources. On the other hand, municipal solid waste (MSW) disposal poses a serious environmental problem. Landfilling of MSW is both costly and polluting. Incineration of MSW to generate energy is a commonly adopted approach. However, there are concerns associated with micro pollutants emitted from the combustion process. The carbon footprint of the process and the environmental cost–benefit balancing are disputable. There is clearly a need to adopt cost-effective alternatives to treat MSW. This paper proposes the potential application of “treated” MSW as an ingredient for construction materials. The treatment process involves placing MSW in an autoclave at 150 °C with 5 bars (0.5 MPa), followed by the separation of metals, plastics and glass for recycling purposes. The end-product, which is a semi-organic mixture (referred to as ‘biomass’), is passed through a vortex-oscillation system, which makes it more uniform as a material. Compressive testing of Portland cement-based pastes containing 10% and 15% biomass shows consistency in the results, demonstrating the potential use of biomass in construction materials.

Assessment and comparison of the environmental performances of a regional incinerator network

In Emilia-Romagna region (Northern Italy) the integrated waste treatment system consists of material collection and recycling, incineration with energy recovery and landfill as final disposal. In particular, at least one incineration plant is working in almost every province of the region. In this work, a screening life cycle assessment approach is applied to seven different incinerators, to compare the different plant technologies and identify the most relevant environmental impacts and processes. The characterization method used in the life cycle impact assessment step is Eco-indicator 99. The functional unit is 1 ton of waste input. As a first result, it can be noted that while the combustion systems are rather similar, the main variables are ascribable to gas cleaning options and efficiency in energy recovery, which result in quite different environmental performances. Among heavy metals, particular attention must be paid to Cd and As, due to their high toxicity, despite their low quantities. The impact due to dioxin emission is orders of magnitude lower than other contaminants (e.g., heavy metals). Furthermore, a catalytic system could be useful for a complete removal of organic contaminants and for a more effective abatement of nitrogen oxides. Finally, the environmental impact assessment sorts the various plants according to their age, i.e., the most recent plants provide the best environmental performances for the same quantity of combusted waste.