Degradation of polymers in unconcentrated and concentrated alkaline urine

Abstract

Source-separated human urine is a valuable resource rich in plant-essential nutrients, but effective nutrient recovery may require use of chemical additives. This study investigated whether such chemicals can be encapsulated in polymers for passive, controlled release to urine. Degradation of four polymers (polypropylene, polylactic acid, polycaprolactone, polyvinyl alcohol) in Ca(OH)2-dosed urine was assessed, to determine their suitability for encapsulated chemical delivery. Thin films of each polymer were fabricated and exposed to either concentrated or unconcentrated alkalised urine for 16 days, with periodic destructive sampling conducted to assess changes in physical structure and morphology. All polymers demonstrated morphological changes and alterations in molecular weight. Degradation of the polymers resulted in a decrease in pH and an increase in urine COD, indicating significant interactions between the polymers and the urine matrix. Polylactic acid and polyvinyl alcohol underwent the highest degradation in urine and were identified as promising candidates for use in an encapsulated chemical delivery system for treating urine.

Keywords

Polymer; Passive chemical dosage; Decentralised sanitation; Nutrient recovery; Source separation; Wastewater treatment

Published in

Environmental technology & innovation
2024, volume: 36, article number: 103880
Publisher: ELSEVIER

SLU Authors

• Deka, Anuron

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • Tezpur University

• Simha, Prithvi

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

• Vinnerås, Björn

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Water Treatment

Publication identifier

• DOI: https://doi.org/10.1016/j.eti.2024.103880

Permanent link to this page (URI)

https://res.slu.se/id/publ/139366