Giomaria Columbu

Progetto di ricerca
Models and methods for strategic evaluation, optimization, and environmental sustainability of waste management assets

The research project focuses on the in-depth study of decision support models and methods for the strategic evaluation of medium and long-term choices related to waste management assets with application both to case studies of the company Iren Ambiente (company where the Industrial Ph.D. took place) and other datasets.

The first part of the research focuses on development and implementation of operational research and linear programming models for the location and sizing of plants. The results of the work concern the formulation of a mixed integer linear programming model that minimizes CO₂ emissions thanks to an efficient distribution of transport flows and the identification of additional intermediate transfer facilities. The model was applied to a real-world case study with significant reduction in CO₂ emissions.

The above study continues extending the model to the bi-objective formulation whereby the costs of the logistics network are minimized as well as the CO₂ emissions. This work provides both single- and multi-period mixed integer linear programming model. A weighted sum approach and an approximated ϵ-constraint algorithm were applied to solve the models on two real-world case studies, obtaining approximated-but-well-structured Pareto sets of non-dominated solutions. The efficacy of the models is also confirmed by further computational experiments on randomly created instances.

The last part of the research focuses on the evaluation of long-term company strategies and policies related to the vehicle replacement in the waste management industry. Some scenarios, characterized by different green policies in terms of choice of traction fuels for new vehicles, are compared from both the financial point of view and the environmental impact related to CO₂ emissions.

Pubblicazioni

• Caselli G., Columbu G., Iori M., Magni C.A. (2022) Mixed Integer Linear Programming for CO2 emissions minimization in a Waste Transfer Facility Location Problem. Proceedings of the 10th International Network Optimization Conference (INOC), Aachen, Germany, June 7–10, 2022 (pp. 51-56)

• Working paper: Caselli G., Columbu G., Iori M., Magni C.A., Oliveira M. (2022). Minimizing costs and CO2 emissions in a waste transfer facility location problem. The manuscript is ready to be submitted to an international journal.

• Working paper: Columbu G., Magni C.A., Baschieri D. (2023). Greening the fleet: financial modeling for vehicle replacement in waste management. Available on Social Science Research Network (SSRN): <https://papers.ssrn.com/abstract=4645735>