Evaluation of the anaerobic degradation of food waste collection bags made of paper or bioplastic

Giovanni Dolci; Valeria Venturelli; Arianna Catenacci; Riccardo Ciapponi; Francesca Malpei; Stefano Ettore Romano Turri; Mario Grosso

doi:10.1016/j.jenvman.2021.114331

Evaluation of the anaerobic degradation of food waste collection bags made of paper or bioplastic

J Environ Manage. 2022 Mar 1:305:114331. doi: 10.1016/j.jenvman.2021.114331. Epub 2021 Dec 24.

Authors

Giovanni Dolci¹, Valeria Venturelli², Arianna Catenacci², Riccardo Ciapponi³, Francesca Malpei², Stefano Ettore Romano Turri³, Mario Grosso²

Affiliations

¹ Politecnico di Milano, Department of Civil and Environmental Engineering (DICA), Piazza Leonardo da Vinci 32, 20133, Milano, Italy. Electronic address: giovanni.dolci@polimi.it.
² Politecnico di Milano, Department of Civil and Environmental Engineering (DICA), Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
³ Politecnico di Milano, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza Leonardo da Vinci 32, 20133, Milano, Italy.

PMID: 34954688
DOI: 10.1016/j.jenvman.2021.114331

Abstract

The amount of compostable bioplastics collected with the food waste is constantly growing, particularly due to the bags used for collection. According to the Italian legislation, compostable bioplastics must be accepted by all biological treatment plants, including aerobic and anaerobic facilities. Anyway, the compostability standard requires only the assessment of the aerobic degradability, while it is generally not required to test the behaviour under anaerobic conditions. This aspect is evaluated in the paper, where the anaerobic degradability of bioplastic bags used for the food waste collection is assessed. First, Biochemical Methane Potential (BMP) tests were performed on four commercial types of bioplastic bags, including those designed only for the collection of food waste and the shoppers, that can be reused for the same purpose. Subsequently, an innovative approach for this kind of substrate was applied, subjecting two bags to semi-continuous co-digestion tests together with the food waste. Both tests were performed by comparing the behaviour of bioplastic bags with that of an alternative collection paper bag. Finally, tests to evaluate the influence of physical phenomena on the degradation of bioplastics were performed to better understand the results of biological tests. BMP tests indicated a good degradability (>71%) of bioplastic bags, while semi-continuous tests showed a much lower degradability (<27%), confirmed by the observation of the undigested bag pieces. On the contrary, the paper bag presents interesting characteristics, because its degradability in the semi-continuous tests (82%) resulted even higher than that observed in the BMP tests (74%). These results highlight an important difference between the bags mono-digestion by means of BMP tests and the semi-continuous co-digestion tests with food waste, which better simulate the full-scale operational conditions.

Keywords: Anaerobic digestion; Bioplastic; Collection bag; Food waste; Paper.

MeSH terms

Anaerobiosis
Bioreactors
Food
Methane
Refuse Disposal*

Substances

Methane