Microbial risk from source-separated urine used as liquid fertilizer in sub-tropical Australia

W. Ahmed, K.A. Hamilton, A. Vieritz, D. Powell, A. Goonetilleke, M.T. Hamilton, T. Gardner
  • Microbial Risk Analysis, April 2017, Elsevier
  • DOI: 10.1016/j.mran.2016.11.005

Assessing risk associated with using urine as a liquid fertilizer

What is it about?

The primary aim of this research study was to evaluate the inactivation rates of a bacterial indicator and a viral surrogate in fresh urine collected from healthy humans, and stored urine at different temperatures and dilutions. Furthermore, Quantitative Microbial Risk Assessment calculations were undertaken to determine the health risk implications in terms of the storage times that would be required to reduce the risks to a target annual probability of infection as recommended by the US EPA. Finally, several possible management intervention measures were discussed to achieve the health risk target.

Why is it important?

The reuse of human urine as fertiliser has received considerable attention due to significant benefits. However, substantial concentrations of could be excreted in urine by an infected individual. Unfortunately, little is known regarding the environmental transmission of these urinary excreted pathogens. Once in the external environment, these pathogens, especially pathogenic bacteria, generally inactivate rapidly due to environmental stresses. However, certain viruses, protozoa, and helminth eggs can survive for several months with the potential to cause infections in humans. Handling of urine with high concentrations of pathogens may pose health risks to collection personnel, farmers, local communities and product consumers.

Perspectives

Professor Ashantha Goonetilleke
Queensland University of Technology

The study results show that an increase in temperature has a more substantial effect on reducing storage time than varying the urine dilution. Combining the Quantitative Microbial Risk Assessment based approach with pathogen reduction interventions as presented in this study provides a range of management options for regulators, and can reduce barriers to the application of source-separated urine associated with long storage times.

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http://dx.doi.org/10.1016/j.mran.2016.11.005

The following have contributed to this page: Professor Ashantha Goonetilleke and Dr Warish Ahmed