Analysis of variance and multi-objective optimization of efficiencies and emission in air/steam rigid and flexible polyurethane foam wastes gasification

Gasification, as one of the most effective thermochemical methods for treatment of various types of waste, has been well studied for biomass, municipal solid waste, and plastic waste. However, polymeric foam waste gasi-fication has not been addressed well and needs to be developed, particularly because of the large volume of such waste produced especially from polyurethane foams. In this regard, air and steam gasification processes for rigid and flexible polyurethane foam wastes were modeled and subjected to multi-objective optimization utilizing a response surface methodology. A multi-criteria decision analysis using TOPSIS (technique for order preference by similarity to ideal solution) was employed to select the gasification process with the best performance with respect to the maximum hydrogen energy and total energy efficiencies and the minimum normalized carbon dioxide emission. It was found that flexible polyurethane foam waste gasification using a steam gasifying agent was the best alternative. Flexible polyurethane foam waste gasification using steam gasifying agent at its opti-mum conditions resulted in a hydrogen energy efficiency of 48.5%, a total energy efficiency of 82.1% and a normalized carbon dioxide emission of 1.69 g. mol(-1), based on the feedstock entering the system.