title: Decomposition pathways and rates of human urine in soils.
abstract: This study proposes a comprehensive reaction network of the soil microbial breakdown of the main compounds in human urine to the end products NH₃ and NH₄⁺. A reactive model was developed and parameters were determined against experimental data. The model was used to assess the amount and release rate of NH₃ and NH₄⁺ in a soil control volume flushed with (i) pulses of urine at various dilutions and (ii) a continuous flow of urine at various dilutions and flow rates. In scenario i, 90% of incoming organic nitrogen was converted to NH₃ and NH₄⁺ between 5 and 20 days from application at rates strongly dependent on the initial microbial soil content. Urea and hippuric acid were largely correlated to NH₃ and NH₄⁺ release, whereas microbial functional groups in the same scenarios were poorly correlated with NH₃ and NH₄⁺ release. In scenario ii, 90% conversion was generally reached for low flow rates and was highly nonlinear with the dilution. Finally, a stochastic analysis showed that urine decomposition was more sensitive to uncertainty in microbial growth rate parameters than half-saturation concentrations.
authors.affiliation: School of Civil Engineering, Building J05, The University of Sydney, Sydney, NSW 2006, Australia. federico.maggi@sydney.edu.au
authors.forename: Federico
authors.initials: F
authors.lastname: Maggi
authors.forename: Edoardo
authors.initials: E
authors.lastname: Daly
mesh_terms: D006090:Gram-Negative Bacteria / Q000254:growth & development / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000254:growth & development / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D014556:Urine / Q000737:chemistry*
chemical_list: D012987:Soil