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Deb, Chinmoy Kanti, 2021. Inhibiting enzymatic ureolysis in human urine with magnesium oxide : a pre-step to semicentralized alkaline urine dehydration. Second cycle, A2E. Uppsala: SLU, Dept. of Energy and Technology

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This thesis investigated the suitability of using MgO to alkalize source-separated fresh human urine at the toilet so that enzymatic ureolysis can be prevented and the urine can be transported and dried off-site without the loss of nitrogen as ammonia. This was assessed by determining the solubility of MgO in urine and the MgO consumption for saturating urine, and evaluating the changes in physicochemical properties of urine when it is saturated with MgO. The effect on MgO solubility of phosphates and organics present in urine and of concentrating urine were also investigated by performing experiments on synthetic, dephosphatized synthetic urine and concentrated fresh urine. Results showed that the solubility of MgO in fresh urine varies between 0.3 and 0.6 g L-1 and ~1 g MgO L-1 is consumed to saturate fresh human urine and increase its pH >10. The solubility of MgO in different types of urine varied as fresh urine > synthetic urine > dephosphatized synthetic urine. Concentrating urine increased the solubility of MgO in it. When MgO-saturated fresh urine was subjected to urease contamination, there was no urea degradation, indicating that MgO saturation is sufficient for inactivation of urease in urine. Based on results obtained in the laboratory, as a prestep to alkaline urine dehydration, a prototype “on-site urine alkalizer” was built and tested. The prototype successfully alkalised 15 L of urine periodically added over a week’s time. For a family of four, 2 kg MgO. year-1 and 5 SEK. year-1 is required to alkalize fresh urine excreted by the family. Therefore, this thesis concluded that the use of MgO for alkalising urine is promising.

Main title:Inhibiting enzymatic ureolysis in human urine with magnesium oxide
Subtitle:a pre-step to semicentralized alkaline urine dehydration
Authors:Deb, Chinmoy Kanti
Supervisor:Simha, Prithvi
Examiner:Wiberg, Karin
Series:Examensarbete / Institutionen för energi och teknik, SLU
Volume/Sequential designation:2021:15
Year of Publication:2021
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:NM029 Soil, Water and Environment - Master's Programme, 120.0hp
Supervising department:(NL, NJ) > Dept. of Energy and Technology
Keywords:decentralized sanitation, , , , , ,, human urine, saturation, solubility, source separation, nutrient recycling, wastewater treatment
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Subject. Use of subject categories until 2023-04-30.:Technology
Deposited On:10 Nov 2021 12:30
Metadata Last Modified:11 Nov 2021 02:01

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