Al-Saadi, Abdullah
- Department of Energy and Technology, Swedish University of Agricultural Sciences
- Tampere University of Applied Sciences
Abstract
Human urine is a promising resource for circular fertiliser production, but its high concentrations of organic and inorganic compounds present both challenges and opportunities for effective treatment. This study evaluates Fenton oxidation for selectively degrading endogenous organic metabolites in acidified, unhydrolysed urine while preserving critical nutrients such as urea. Using targeted metabolomics, over 200 organic metabolites were identified in urine, with creatinine, citric acid, hippuric acid, and methylhistidine comprising half of the total organic metabolite load (Sigma OMs = 3.23 g L-1). Under optimised conditions (pH 4.0, 1:1 Fe2+: H2O2 molar ratio), 59 % of Sigma OMs were degraded in unconcentrated urine treated with 1 g H2O2 L-1. Increasing the H2O2 dose in unconcentrated urine, or treating concentrated urine obtained through evaporative water removal, resulted in higher Sigma OMs degradation but also increased urea oxidation, highlighting a trade-off between efficient COD removal and nutrient recovery. COD removal was 38 % at pH 4.0 and 27 % at pH 6.0, suggesting that Fenton oxidation could be applied to H2O2 stabilised urine without strict pH adjustment. Real urine differed significantly from synthetic urine, requiring five times more Fe2+ catalyst for complete H2O2 activation, with peroxide consumption occurring within five minutes compared to two hours in synthetic urine. Organic compounds in urine scavenged Fe3+, forming iron-organic complexes that disrupted Fe2+ regeneration and contributed to iron precipitation at higher pH values. These findings demonstrate that Fenton oxidation can be optimised to achieve selective degradation of undesirable organics while preserving plant-essential nutrients in urine collected within resource-oriented sanitation systems.
Keywords
Advanced oxidation; Wastewater treatment; Resource recovery; Source separation; Peroxide; Sustainable sanitation
Published in
Chemical Engineering Journal Advances
2025, volume: 23, article number: 100772
Publisher: ELSEVIER
SLU Authors
Simha, Prithvi
- Department of Energy and Technology, Swedish University of Agricultural Sciences
- Department of Energy and Technology, Swedish University of Agricultural Sciences
UKÄ Subject classification
Water Treatment
Separation Processes
Publication identifier
- DOI: https://doi.org/10.1016/j.ceja.2025.100772
Permanent link to this page (URI)
https://res.slu.se/id/publ/142179