Material flow analysis as a support tool for multi-criteria analysis in solid waste management decision-making

When a waste management system (WMS) has been evaluated and rated ineffective, there is an impetus to decide on sound corrective action. Intervention actions often take the form of new policies, programs, or new capital intensive projects which may have far-reaching implications on the welfare of societies. For this reason, decision making around these intervention actions must make use of tools designed to handle complex problems involving multiple and often conflicting criteria, for example, multi-criteria decision analysis (MCDA). In this paper, material flow analysis (MFA) is presented as a support tool prior to a full MCDA. In the approach proposed, MFA plays the critical role in evaluating the effectiveness of a WMS and assessing the degree of improvement the proposed solutions may provide. A case study based on a practical situation in Zimbabwe is used to illustrate this relationship between MFA and MCDA. Data for the MFA were obtained from both literature and field measurements. A number of techniques were applied in the subsequent analyses, including scenario modeling. The evaluation concluded the case area's WMS to be weak, and revealed that a new policy aiming at revising the MSW recycling target to at least 19%, promoting organic waste composting at-source, and setting up a medium scale anaerobic digestion plant represent the set of intervention actions that bring optimal benefits to the WMS from both a technical perspective and in view of the decision-makers' preference. The study demonstrates the value that MFA can add to waste management decision-making where multi-criteria analysis is involved.