Polyamide 6 microplastics facilitate methane production during anaerobic digestion of waste activated sludge

Hongbo CHEN, Mengge TANG, Xiao YANG, Yiu Fai TSANG, Yanxin WU, Dongbo WANG, Yaoyu ZHOU

Research output: Contribution to journalArticlespeer-review

Abstract

Polyamide 6 (PA6) as a typical emerging microplastic pollutant has frequently been featured in wastewater treatment plants (WWTPs), yet its associated impact on waste activated sludge (WAS) anaerobic digestion process have not been fully understood. This study identified the key role of PA6 microplastics (5–50 particles/g TS) in methane production during anaerobic digestion through biochemical methane production testing and model-based analysis, and explored the mechanism involved by monitoring the conversion of metabolic intermediates, the activity of key enzymes, and the effects of leachate caprolactam (CPL). Unlike other microplastics that normally inhibit anaerobic digestion, PA6 significantly enhanced methane production due to the effect of CPL. The presence of 10 particles PA6/g TS improved methane production by 39.5% (from 124 ± 6 to 173 ± 8 L CH4/kg VS). Model-based analysis showed that PA6 promoted methane production potential and volatile solids destruction. PA6 offered marginal effect on the solubilization and hydrolysis of WAS, the leaching of CPL improved acidification and methanogenesis due to the promotion of key enzyme activities, which is the main reason why PA6 increased methane production. These findings indicate that PA6 is less toxic to WAS anaerobic digestion than other microplastics, which prompts an understanding of the dual role of microplastics in WWTPs. Copyright © 2020 Elsevier B.V.
Original languageEnglish
Article number127251
JournalChemical Engineering Journal
Early online date09 Oct 2020
DOIs
Publication statusE-pub ahead of print - 09 Oct 2020

Citation

Chen, H., Tang, M., Yang, X., Tsang, Y. F., Wu, Y., Wang, D., & Zhou, Y. (2020). Polyamide 6 microplastics facilitate methane production during anaerobic digestion of waste activated sludge. Chemical Engineering Journal. Advance online publication. doi: 10.1016/j.cej.2020.127251

Keywords

  • Polyamide 6
  • Microplastics
  • Methane production
  • Waste activated sludge
  • Anaerobic digestion

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