EVALUATION OF THE APPLICATION OF MUNICIPAL SOLID WASTE INCINERATOR (MSWI) ASH IN CIVIL ENGINEERING USING A SUSTAINABILITY APPROACH

Abstract

Incineration is regarded as one of the common methods for energy recovery as well as waste reduction, due to the high amount of waste generation in major cities; for instance Tehran (7000-8000 ton/day), and lack of sufficient landfill. The proper treatment and recycling of municipal solid waste incinerator (MSWI) residual ashes is one of the challenges which decision makers are faced with. In order to investigate the feasibility of the recycling of ashes, the sustainability index is considered. This evaluation is carried out by means of the multi-criteria decision-making approach for assessing sustainability (MIVES) and the Analytical Hierarchy Process (AHP) as a conventional decision-making tool. Six possible scenarios in Iran was determined, BA/FA landfilled with solid waste system (current scenario), Partial substitute of raw materials for cement/concrete, Ceramics and glass/glass-ceramics production, Geotechnical applications, use of BA/FA as alternative adsorbent and Fertilizers in agricultural soils. The assessment was accomplished through 25 questionnaires distributed among experts which includes environmentalists, governmental decision makers, academics, and technical groups. The questionnaires comprised of 33 pairwise comparison matrices, and the experts were asked to systematically compare elements of the constructed hierarchy in numerical terms. According to the results, reusing MSWI ash as a partial substitute for raw materials in cement/concrete scored highest in ranking among other potential MSWM scenarios (with a relative weight of 0.234). The results also reveal that the utilization of BA/FA as alternative adsorbents and as fertilizers in agricultural soils are not to be currently pursued in Iran (with relative weights of 0.117 and 0.129 respectively).