Bioconversion Process of Polyethylene from Waste Tetra Pak^® Packaging to Polyhydroxyalkanoates

Area of Science:

• Biotechnology
• Polymer Science
• Waste Management

Background:

• Tetra Pak® packaging presents a significant waste stream due to its complex material composition.
• Polyethylene (PE-T) is a major component of Tetra Pak® and a potential carbon source for biopolymer synthesis.
• Polyhydroxyalkanoates (PHAs) are biodegradable polyesters with diverse applications, offering a sustainable alternative to conventional plastics.

Purpose of the Study:

• To investigate a novel recycling method for waste Tetra Pak® packaging.
• To utilize the polyethylene (PE-T) fraction as a carbon source for polyhydroxyalkanoates (PHA) biosynthesis.
• To characterize the PHA produced and validate the bioconversion process.

Main Methods:

• Separation of polyethylene (PE-T) from waste Tetra Pak® using a solvent method.
• Cultivation of Cupriavidus necator H16 bacteria in media supplemented with PE-T.
• Monitoring bacterial growth and PHA accumulation.
• Characterization of synthesized PHA using NMR, FTIR, ESI-MS/MS, GPC, and AMS.

Main Results:

• Cupriavidus necator successfully utilized PE-T as a carbon source for PHA production.
• PHA accumulation reached up to 40% w/w in nitrogen-rich TSB media supplemented with PE-T.
• Characterization confirmed the presence of 3-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate co-monomeric units in the PHA.
• AMS analysis confirmed the biogenic origin of the PHA, with 96.73% modern carbon.

Conclusions:

• The proposed recycling method is feasible for waste Tetra Pak® packaging.
• Waste Tetra Pak® can be valorized into value-added PHAs.
• 14C analysis is a reliable method for validating bioconversion processes using waste materials.