Exploring into a light-avoided environment: Mechanical-thermal coupled conditions responsible for the aging behavior of plastic waste in landfills

Qiujie Huang; Changfu Yang; Zhaowen Cheng; Hui Wang; Amin Mojiri; Nanwen Zhu; Xiaoyong Qian; Yilong Shen; Shaolin Wu; Ziyang Lou

doi:10.1016/j.watres.2023.120162

Exploring into a light-avoided environment: Mechanical-thermal coupled conditions responsible for the aging behavior of plastic waste in landfills

Water Res. 2023 Aug 15:242:120162. doi: 10.1016/j.watres.2023.120162. Epub 2023 Jun 3.

Authors

Qiujie Huang¹, Changfu Yang¹, Zhaowen Cheng², Hui Wang¹, Amin Mojiri¹, Nanwen Zhu³, Xiaoyong Qian⁴, Yilong Shen⁵, Shaolin Wu⁵, Ziyang Lou⁶

Affiliations

¹ Shanghai Engineering Research Center of Solid Waste Treatment and Resource, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
² School of Resource Environment and Safety Engineering, University of South China, Hengyang 421001, China.
³ Shanghai Engineering Research Center of Solid Waste Treatment and Resource, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
⁴ Shanghai Academy of Environmental Sciences, Shanghai 200233, China.
⁵ Shanghai Solid Waste Management Center, Shanghai 200235, China.
⁶ Shanghai Engineering Research Center of Solid Waste Treatment and Resource, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China. Electronic address: louworld12@sjtu.edu.cn.

PMID: 37307685
DOI: 10.1016/j.watres.2023.120162

Abstract

Plastics in landfills undergo a unique micronization process due to multi-factor and light-avoided conditions, but their aging process in such a typical environment remains unexplored. This study investigated the aging behavior of polyethylene plastics, representative of landfills, under simulated dynamic mechanical forces and high temperature-two prevalent environmental factors in landfills. The study explored the individual and combined contributions of these factors to the aging process. Results indicated that high temperature played a primary role in aging plastics by depolymerization and degradation through ·OH production, while mechanical forces contributed mainly to surface structure breakdown. The combined effect leads to more serious surface damage, creating holes, cracks, and scratches that provide access for free radical reactions to plastic bulk, thereby accelerating the aging and micronization process. The resulting microplastics were found to be 14.25 ± 0.53 μg L^-1. Aged plastics exhibit a rapid aging rate of depolymerization and oxidation compared to virgin plastics due to their weak properties, suggesting a higher potential risk of microplastic generation. This study fills a knowledge gap regarding the aging behavior of plastics under complex and light-avoided landfill conditions, emphasizing the need for increased attention to the evolution process of microplastics from aged plastic waste in landfills.

Keywords: Aging behavior; Landfill; Mechanical-thermal coupled conditions; Microplastics; Plastics.

MeSH terms

Microplastics
Plastics / chemistry
Refuse Disposal* / methods
Waste Disposal Facilities
Water Pollutants, Chemical*

Substances

Plastics
Microplastics
Water Pollutants, Chemical