Lactic Acid Fermentation of Human Urine to Improve its Fertilising Value and Reduce Odour Emissions
Co-authored with N. Andreev, M. Ronteltap, B. Boincean, E. Zubcov, N. Bagrin, N. Borodin, and P.N.L. Lens
Published in Journal of Environmental Management (198) 63–69, April 12, 2017.
The ongoing urine fermentation experiments during the Soil Feeder project in Canberra and The Zero Organic ‘Waste’ Home in Hong Kong were able to support and inform the applied microbiology research of Nadejda Andreev and her cohort at UNESCO-IHE Institute for Water Education with usability aspects.
Lactic acid fermentation of urine – employed in the Anthroponix study of this research – affords stabilisation and odour reduction by preventing ammonia volatilisation. Fermentation improves collection handling of source-separated urine and its nutrients retention. In this technique, lactic acid bacteria are sourced from sauerkraut brine (fermented cabbage juice), then propagated with sugar input prior to urine collection which leads to acidification (pH reduction) in anaerobic storage. Compared to urine stored with airflow, undesirable ammonia content in fermented urine is reduced by at least one third
and the lactic acid bacteria strains remain viable in high concentrations (7.3 CFU/ml) after one month of curing.
In joint olfactory testing trials at the researcher’s Zero Organic ‘Waste’ Home in Hong Kong, and Nadejda Andreev’s farm lab in Moldovia, an odour acceptability index was developed to conduct a survey. It pointed to the significant reduction of perceived odour strength in the fermented urine, increasing its acceptance. The evaluation of fertilizer value with seed germination tests showed how fermented urine impacted plant growth beneficially compared to untreated urine. Aside from sealed canisters, lacto-fermentation was also applied to large urine tanks with open airflow, where it reduced, to a lesser degree, the emissions of odour and ammonia. Urine fermentation has a potential in larger scale applications such as irrigated farming because stabilised urine minimises phosphorus precipitation, which commonly blocks drip irrigation systems.
Keywords: Human urine, lactic acid fermentation, urine hydrolysis, nutrient recycling, odour emissions control, ecological sanitation.