Abstract
Due to the growing amount of residues in Europe, it is mandatory to provide a viable alternative for managing wastes contributing to the efficient use of resources. Besides, it is also essential to move towards a low carbon economy, priority EU by 2050. Among these, it is important to highlight the development of sustainable alternatives capable of incorporating different kind of wastes in their formulations.Municipal Solid Waste Incineration (MSWI) is estimated to increase in Europe, where the accessibility of landfill is restricted. Bottom ash (BA) is the most significant by-product from MSWI as it accounts for 85 - 95 % of the solid product resulting from combustion. BA is a mixture of calcium-rich compounds and others silicates enriched in iron and sodium. In addition, it is categorized as non-hazardous waste which can be revalorized as secondary material in construction or civil engineering fields, previous weathering stabilization during 2 - 3 months. Taking into account the relative proportion of each size fraction and the corresponding material characterization, the content of glass (primary and secondary) is estimated to be around 60 wt%. Furthermore, as a renewable resource and according to waste management European policies, residual agricultural biomass has attracted attention in preparation of advanced materials for various applications, due to their low cost, abundance, and environment friendliness. Among this residual biomass, rice husk is a by-product of rice milling industry which has high content of silica and has been widely used in buildings as natural thermal insulation material.Weathered BA (WBA) with a particle size less than 30 mm was milled under 100 μm, mixed with 2.0 - 5.0 mm rice husk, formed into ball-shaped pellets and sintered by different thermal treatments, which remove the organic matter content generating a large porosity. Physico-chemical analysis and mechanical behavior of the manufactured lightweight aggregates were tested. The obtained results provide a suitable physico-mechanical formulation using WBA as silica source, as well as a common crop by-product.
Highlights
Incineration of municipal solid waste (MSW) in waste-to-energy plant is expected to increase all over the world because the increase in consumption and the use of landfills is limited [1]
Because of its high glass content and the possibility to encapsulate the heavy metals contained, which increasing its reuse, an attractive way to reuse weathering stabilization (WBA) could be as a resource in the formulation of lightweight aggregates [24], while Rice husk (RH) could be used to increase the porosity, providing in turn amorphous-Si to improve the cohesive forces between particles
The X-Ray Fluorescence (XRF) results agreed with the material characterization of WBA, which is mainly composed by lime-soda-glass, the most prevalent type of glass used in bottles
Summary
Incineration of municipal solid waste (MSW) in waste-to-energy plant is expected to increase all over the world because the increase in consumption and the use of landfills is limited [1]. Rice husk (RH) is an agricultural by-product comprising 40 % cellulose, 30 % lignin and 20 % silica [17] and, after combustion, its ash (RHA) is mainly composed of silica ( > 90 %), most of which is amorphous depending on the temperature as well as the duration of the calcination process [13] It is reported elsewhere [18] that RHA may be a residue with high economic potential, because it can be an alternative to alkali silicates (e.g. as raw material in the cement industri), while an agricultural by-product is valorized as energetic biomass. Characterization of the lightweight aggregate by means compression as mechanical property and shrinkage was evaluated
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