Treatment technologies of cellulose-based bio-plastic waste: an experimental and theoretical investigation

The contribution aims to evaluate the effect of a cellulose-based bio-plastic waste (cellulose acetate) on the current Italian Municipal Solid Waste (MSW) management system. Three main scenarios were proposed, assuming the collection of cellulose acetate waste with organic, plastic and mixed waste streams respectively. The treatment routes of organic, plastic and mixed waste were considered as a combined anaerobic digestion and composting process, mechanical sorting and recycling and mechanical-biological treatment followed by incineration, respectively. For the scope, experimental activities have been carried out in order to estimate the performance of each treatment from a technical point of view, described as performance of the process and performance of the outputs. Based on the technical results, environmental and economic assessments have been carried out in order to evaluate the carbon footprint and the total cost of the whole waste management system for each scenario. From each evaluation, three indices were calculated and combined through a multi-criteria decision analysis to identify the preference of the different scenarios according to four decision-makers. Results have revealed how, despite the presence of cellulose acetate resulted in no effect or small improvement in the process for organic and plastic treatment, the outputs were strongly affected by the presence of bio-plastic. On the other hand, during mixed waste treatment, cellulose acetate did not influence the process as well as the output was slightly improved. These achievements were applicable also to environmental and economic analysis. Both evaluations revealed that cellulose acetate performed worst when handled with organic waste, while the treatment of plastic and mixed waste with cellulose acetate gave similar and better results. The main reason for this result was the non-conformity of compost quality when treating cellulose acetate with organic waste, which limited the use of compost in agriculture. These results were combined through the multi-criteria decision analysis approach, which showed a reference for the treatment of cellulose acetate with mixed waste, while the one in organic one was significantly low. Finally, the contribution suggests the necessity to upgrade the current organic waste management system to increase the performance of bio-plastic waste treatment, which is the strategy pursued by Italy.