Ranking sewage sludge management strategies by means of Decision Support Systems: A case study

• Agriculture, Incineration, Cement Kiln, Wet Ox were ranked for a real case study.
• A comprehensive assessment procedure based on about 30 parameters is proposed.
• Technical, social, legislative, environmental, economic aspects are considered.
• Two different DSSs have been used and compared.
• A novel make-AND-buy integrated methodology is proposed.

Waste management planning is a complex task involving a variety factors and professional skills. In order to avoid oversimplification leading to the risk of adopting inappropriate solution the relevant decision problems should be tackled with: (a) a comprehensive decision model (including technical, environmental, economic, social, etc. factors) and (b) a suitable decision supporting tool. In this work as far as (a) is concerned we propose a model based on more than 30 parameters for the evaluation of sewage sludge management strategies. As to (b) we implemented this model by employing both a worksheet (“home made” option) and a DSS commercially available (“buy” option). As a case study, we considered the selection of the sewage sludge management strategy in a 500,000 inhabitants area comparing the following alternatives: Agricultural use, Incineration, Wet Oxidation and recovery in Cement Kiln. The assessment of the four alternatives led to the following preference order: Agricultural use ≫ Incineration > Cement Kiln ≅ Wet Oxidation. Finally, a discussion on the make-or-buy dilemma and on pros and cons of decision support methods is reported. As a result, a paradigm shift defined make-and-buy approach is proposed.