Environmental Engineering Reference
In-Depth Information
environmental issues. Moreover, public/private sectors consideration and public participation
considerations make the problem even more complex.
Chang et al. (2005) assess that installing material recovery facilities (MRFs) in a solid
waste management system could be a feasible alternative to achieve sustainable development
goals in urban areas. They formalize a decision model for the optimal site selection and
capacity planning for a MRF in conjunction with an optimal shipping strategy of solid waste
streams in a multi-district urban region. Screening of material recovery and disposal capacity
alternatives can be achieved in terms of economic feasibility, technology limitation, recycling
potential, and site availability. The optimization objectives include economic impacts
characterized by recycling income and cost components for waste management, while the
constraint set consists of mass balance, capacity limitation, recycling limitation, scale
economy, conditionality, and relevant screening constraints.
A fundamental difficulty in planning a Municipal Solid Waste (MSW) management
system is the necessity of taking simultaneously into account conflicting objectives. It is
really difficult for planners and regulators to develop a sustainable approach to waste
management and to integrate strategies aiming at producing the best practicable and
environmentally sustainable option. To formalize these strategies, in the last two decades,
considerable research efforts have been directed towards the development of economic-based
optimization models for MSW flow allocation. Several examples of mathematical
programming models have been developed for MSW management planning, such as, for
example, in Chang and Chang (1998), D'Antonio and Fabbricino (1998), Daskalopoulos et al.
(1998), Fiorucci et al. (2003), Badran and El-Haggar (2005).
However, an approach to the waste management problem merely based on economic
considerations cannot be considered as completely satisfactory, and a wide set of possible
improvements can be pursued. Above all, modeling the environmental impact of solid waste
management requires modeling and analyzing a quite heterogeneous set of subsystems,
which, in turn, are affected by the decisions concerning solid waste management. Examples
of such subsystems are the atmospheric pollution model, the city traffic system, the sanitary
landfill, etc. In this respect, Tsiliyannis (1999) has discussed the main environmental
problems related to MSW management, and in particular those concerning pollutant releases.
Another possible approach is based on life cycle assessment (Finnveden, 1999; Barton et
al., 1998) and Finnveden (1999) has discussed some methodological issues arising in this
case. More recently, Costi et al. (2003) have proposed a decisional strategy that takes into
account the environmental impact of MSW in the constraints of the model.
Clearly, the necessity of taking into account economic, technical, normative aspects,
paying particular attention to environmental problems (which usually cannot be dealt with by
economical quantifications only) is more and more felt. Such a reason has led several authors
to propose multi-criteria decision approaches that, in some cases, allow a formal
representation of uncertainty or imprecise information. Recently, several authors have
proposed a number of models and tools based on outranking approaches for multiple criteria
decision making (MCDM) and multiattribute rating techniques applied to MSW management.
Such approaches have paid a special attention to the different aspects (economic, technical,
normative, environmental) of the decision process. Among others, the following
methodologies have been proposed: Electre III [Hokkanen and Salminen, 1997], and DEA
ranking techniques [Sarkis, 2000].
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