Anaerobic digestion of commercial PLA and PBAT biodegradable plastic bags: Potential biogas production and 1H NMR and ATR-FTIR assessed biodegradation

Sergio Joaquín Álvarez-Méndez; Juan Luis Ramos-Suárez; Axel Ritter; Javier Mata González; Ángeles Camacho Pérez

doi:10.1016/j.heliyon.2023.e16691

Anaerobic digestion of commercial PLA and PBAT biodegradable plastic bags: Potential biogas production and ¹H NMR and ATR-FTIR assessed biodegradation

Heliyon. 2023 May 26;9(6):e16691. doi: 10.1016/j.heliyon.2023.e16691. eCollection 2023 Jun.

Authors

Sergio Joaquín Álvarez-Méndez^{1

2}, Juan Luis Ramos-Suárez¹, Axel Ritter³, Javier Mata González¹, Ángeles Camacho Pérez¹

Affiliations

¹ Departamento de Ingeniería Agraria y del Medio Natural. Universidad de La Laguna. La Laguna, Tenerife, Spain.
² Instituto Universitario de Bio-Orgánica Antonio González, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, 38206 La Laguna, Tenerife, Spain.
³ Área de Ingeniería Agroforestal, Universidad de La Laguna, Spain.

Abstract

Bioplastics aim to substitute conventional plastics in most applications, a critical one being the collection of organic wastes for composting or anaerobic degradation. The anaerobic biodegradability of six commercial bags composed of PBAT or PLA/PBAT blends and certified as compostable [1] was studied using ¹H NMR and ATR-FTIR techniques. This study aims to elucidate if commercial bioplastic bags are biodegradable under conventional conditions found in anaerobic digestates. Results showed that all studied bags are hardly anaerobically biodegradable at mesophilic temperatures. The biogas yield resulting from the anaerobic digestion under laboratory conditions oscillated between 270.3 ± 45.5 L kgVS^-1 for a trash bag composed of 26.64 ± 0.03%/73.36 ± 0.03% PLA/PBAT and 36.7 ± 25.0 L kgVS^-1 for a bag composed of 21.24 ± 0.08%/78.76 ± 0.08% PLA/PBAT. The degree of biodegradation did not correlate with PLA/PBAT molar composition. However, ¹H NMR characterization showed that the anaerobic biodegradation occurred mostly in the PLA fraction. No bioplastics biodegradation products were detected in the digestate fraction (<2 mm). Finally, none of the biodegraded bags comply with the EN 13432 standard.

Keywords: Anaerobic digestion; Biochemical methane potential; Bioplastics; PBAT; PLA.