Degradability of petrochemical and bio-based plastic by microorganisms | |
| Author | Chanya Prachakrich |
| Call Number | AIT Thesis no.EV-25-02 |
| Subject(s) | Microplastics--Biodegradation Biodegradable plastics |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Plastics have been widely used in the past and continue into the present, especially during the COVID-19 pandemic, when single-use plastics became an urgent problem projected to exceed 1.23 billion tons by 2060. However, there is an insufficiency of effective plastic waste management, particularly with single-use plastics, mainly in food packaging products in Thailand. This plastic is always discarded with organic waste, ending up in household compost or landfills, also being transported in ambient conditions. This lack of management results in environmental pollution in soil, water, air, and etc. due to the widespread dispersal of plastic garbage. In this study, the degradation of three plastic types—PET, PP, and PLA/PBAT— was examined under UVA/B radiation and composting conditions over a period of six months to compare material transformations under simulated environmental conditions and to investigate biofilm development for bioremediation purposes, aiming to understanding effects of sunlight and compost on plastics. The results were assessed through weight loss analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), along with environmental factors that could influence the degradation rate of plastics. The analysis results indicated that PP exhibited the highest degradation under UV radiation. With a weight loss of 11.42±0.26% and turned into microplastics, which is greater than PLA/PBAT (3.53±1.28%) and PET (0.13±0.11%), and this aligns with the FTIR results that showed the creation of C=O. Under compost conditions, PLA/PBAT exhibited the highest degradation rate of 23.37±0.93% without leaving microplastics with the size of 0.3 mm to 5 mm, and FTIR exhibited signs of microbial breakdown (C=O, –OH groups), but PET and PP did not experience any weight loss from biodegradation. However, the results of biofilm formation from SEM analysis indicated that different microbial communities colonize particular types of polymers. Additionally, the statistical analysis revealed that the degradation rate of PLA/PBAT increased when the temperature decreased under UV radiation experiment. For compost conditions, there was no relationship between the degradation rate and soil parameters. Only the correlation among soil parameters was identified. Ultimately, the study of degradation under UV and compost help understanding the fate of plastic packaging, frequently found in common scenarios due to improper management, and comprehending their degradability sheds light on their fate under these circumstances. |
| Year | 2025 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Water Resources and Environmental Engineering (DWREE) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Cruz, Simon Guerrero;Ghimire, Anish (Co-Chairperson); |
| Examination Committee(s) | Anal, Anil Kumar;Xue, Wenchao; |
| Scholarship Donor(s) | Her Majesty the Queen's Scholarships (Thailand); |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2025 |