Incorporation of main line impact into life cycle assessment of nutrient recovery from reject water using novel membrane contactor technology

Sofia Högstrand, Juho Uzkurt Kaljunen*, Raed A. Al-Juboori, Karin Jönsson, Hamse Kjerstadius, Anna Mikola, Greg Peters, Magdalena Svanström

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)


Wastewater treatment plant (WWTP) nutrient recovery has recently gained traction in the search for new pathways for fertilizer production. In particular, concentrated waste streams such as reject water from sludge digestion are suitable. The environmental impact of a novel nutrient recovery technology using a membrane contactor (NPHarvest) was examined with an environmental life cycle assessment (LCA). Impact hotspots were benchmarked against a comparable technology (struvite precipitation and ammonia stripping), and the impacts of the two technologies were found to be similar for most studied environmental impact categories. To allow for the inclusion of effects on other parts of the WWTP while limiting the general system boundaries to the reject water treatment, a novel approach to capture the main line impact was developed. The effects on the main line contributed substantially to the overall results. The overall results indicated clear nutrient recovery benefits related to substituted materials in mineral fertilizer production. Additionally, reject water nutrient recovery provided even greater benefits due to reduced N2O emissions and the reduced use of precipitation chemicals in the WWTP main line. Nonetheless, both nutrient removal and recovery were necessary for the two technologies to reach a net zero climate impact in their current pilot scales. Further development of the NPHarvest technology—such as mitigating NH3 emissions, exploring alternative input chemicals and optimizing energy consumption (especially for crystallizing the ammonium salt solution that is produced)—is recommended before full-scale implementation.

Original languageEnglish
Article number137227
Number of pages13
JournalJournal of Cleaner Production
Publication statusPublished - 1 Jul 2023
MoE publication typeA1 Journal article-refereed


  • Main line impact model
  • Municipal wastewater
  • Nitrogen
  • Phosphorus
  • Recovery


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