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Abstract

The coexistence of pharmaceuticals and microorganisms in source separated urine poses a risk for the development of antimicrobial resistance (AMR), especially when urine-based fertilizers are applied to soils. While prior studies have investigated pathogen inactivation in source-separated wastewater matrices, few have evaluated the simultaneous fate of antibiotic-resistant bacteria (ARBs) and their corresponding resistance genes (ARGs) in real urine matrices, particularly under alkaline conditions. Here, we studied the inactivation of beta-lactamase-producing Escherichia coli and vancomycin-resistant Enterococcus faecium and the degradation of their respective ARGs (bla(CTX - M) and van-A) in alkalized, unhydrolyzed urine (pH 10.8 and 12.5) treated with UV (65 W low pressure dichromatic mercury lamp at 185/254 nm), hydrogen peroxide (1.25 g L-1 H2O2), and their combination (UV/H2O2). UV/H2O2 treatment resulted in >7 log(10) inactivation of both ARBs, with inactivation rate constants of -0.058 log(10) cfu min(-1) (E. coli, UV) and -0.093 log(10) cfu min(-1) (E. faecium, UV/H2O2). In contrast, ARG reduction was limited with UV alone and negligible with H2O2 alone. Gene copy reductions of 3 log10 (bla(CTX - M), k = -0.055 log10 copies min(-1)) and 2 log10 (van-A, k = -0.040 log10 copies min(-1)) were observed under UV/H2O2. Notably, brief storage (>3 h) at pH 12.5 achieved similar ARB inactivation and ARG reduction as 80 min of UV/H2O2 treatment at pH 10.8, offering a low-energy alternative for sanitizing source-separated urine.

Keywords

fertilizer; microbial risk; safe nutrient recycling; pathogens; source separation; wastewater; hygienisation

Published in

Frontiers in Microbiology
2025, volume: 16, article number: 1605625

SLU Authors

UKÄ Subject classification

Water Treatment

Publication identifier

  • DOI: https://doi.org/10.3389/fmicb.2025.1605625

Permanent link to this page (URI)

https://res.slu.se/id/publ/143529