Implementation of a Multicriteria Sewage Sludge Management Model in the Southern Québec Municipality of Lac-Mégantic, Canada

Abstract

This paper deals with the evaluation of solutions to resolve a problem of sewage sludge management in the rural municipality of Lac-Mégantic. In order to develop a consensus, an advisory committee representative of the population has studied the possible solutions and has made recommendations to municipal decision-makers. A panel of experts from the Université de Sherbrooke (STOPER research team) provided the committee with information concerning the various aspects of sewage sludge management. Four principal solutions were retained: composting, landfilling, land application and incineration. The decision model included criteria employed in the analysis of the waste management problem relying on inter-disciplinary principles: economics, technological aspects, environmental risks, human health risks and social perception. The committee members were asked to evaluate each solution on the basis of information provided by the STOPER research team by ranking each criterion of each solution. The STOPER research team developed a more detailed impact matrix by estimating several subcriteria and combinations of solutions. Three multicriteria decision-making methods (weighted sum, Electre and fuzzy set theory) were used to analyse the impact matrices obtained from the advisory committee and the STOPER research team. Monte Carlo simulations were used to take into account the uncertainties relative to the estimation of criteria and weights, and to verify the stability of potential solutions. In the present case study, all the methods show that there is a real consensus in the choice of sludge management strategies. Composting and land application represent the two most interesting and wanted solutions for the municipality. The Monte Carlo simulations show, however, that a clear preference cannot be established between these two disposal methods.