Drying fresh human urine in magnesium-doped alkaline substrates: Capture of free ammonia, inhibition of enzymatic urea hydrolysis & minimisation of chemical urea hydrolysis

The inhibitory effect of ozone and hydrogen peroxide (HP) on urea hydrolysis in stored urine was investigated and compared. Ozone showed less effect on urea hydrolysis due to the complicated composition of urine (including a large amount of urease-producing bacteria) and bacteria regeneration. Ozone concentration and total heterotrophic bacteria analysis demonstrated that residual ozone concentration decreased by 43% within 15 hr from 13.50 to 7.72 mg/L in the one-time ozonation urine test, and finally completely decomposed within 4 days. In addition, bacteria regenerated quickly after ozone completely decomposed. However, HP showed a significant effect on inhibiting urea hydrolysis not only in stored urine but also in fecal-contaminated urine. The suitable doses of applied HP to inhibit urea hydrolysis in stored urine, concentrations of 0.5 and 1.0 g feces per liter of fecal-contaminated urine, were 0.03, 0.16 and 0.23 mol/L, respectively. The urea concentrations after 2 months stored were 7,145, 7,109 and 7,234 mg/L, respectively.

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A targeted study on possible free ammonia inhibition ofNitrospira

Journal of Environmental Engineering and Science ◽

10.1139/s05-044 ◽

2006 ◽

Vol 5 (5) ◽

pp. 365-376 ◽

Cited By ~ 11

Author(s):

R A Simm ◽

D S Mavinic ◽

W D Ramey

Keyword(s):

Free Ammonia ◽

Ammonia Inhibition

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Unraveling the literature chaos around free ammonia inhibition in anaerobic digestion

Renewable and Sustainable Energy Reviews ◽

10.1016/j.rser.2019.109487 ◽

2020 ◽

Vol 117 ◽

pp. 109487 ◽

Cited By ~ 22

Author(s):

G. Capson-Tojo ◽

R. Moscoviz ◽

S. Astals ◽

Á. Robles ◽

J.-P. Steyer

Keyword(s):

Anaerobic Digestion ◽

Free Ammonia ◽

Ammonia Inhibition

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Nitrite accumulation in submerged biofilters - combined effects

Water Science & Technology ◽

10.2166/wst.1996.0453 ◽

1996 ◽

Vol 34 (3-4) ◽

pp. 371-378 ◽

Cited By ~ 10

Author(s):

F. Fdz-Polanco ◽

S. Villaverde ◽

P. A. Garcia

Keyword(s):

Ammonia Concentration ◽

Relative Activity ◽

Free Ammonia ◽

Effect Of Temperature ◽

Ammonia Oxidizer ◽

Ammonium Concentration ◽

Nitrite Accumulation ◽

Biological Aerated Filter ◽

Ammonia Inhibition ◽

Aerated Filter

The combined effect of temperature, pH and ammonium concentration over the nitrite accumulation phenomena in situations of free ammonia inhibition, their effect over the ammonia and nitrite oxidizer microorganiisms influence over the nitrification, have been studied in an Up-flow Biological Aerated Filter (UBAF). The free ammonia inhibition effect highly depends on the values of pH, temperature and ammonium concentration. For the same specific free ammonia concentration different values of temperature, pH and ammonium concentration bring about different nitrite accumulations. In conditions of no free ammonia inhibition and low values of temperature and pH, high ammonium concentrations bring about a higher relative activity of ammonia oxidizer microorganisms of the filter increases the nitratation efficiency in zones close to the outlet and will favour the nitrite accumulation in situations of free ammonia inhibition.

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Fertilizer from dried human urine added to ash and lime – a potential product from eco-sanitation system

Water Science & Technology ◽

10.2166/wst.2016.324 ◽

2016 ◽

Vol 74 (6) ◽

pp. 1436-1445 ◽

Cited By ~ 11

Author(s):

Shanta Dutta ◽

Björn Vinnerås

Keyword(s):

Mass Balance ◽

Human Urine ◽

Low Temperatures ◽

Evaporation Rate ◽

Nitrogen Loss ◽

Urea Hydrolysis ◽

Drying Process ◽

High Ph ◽

Feasible Option ◽

Rate Of Evaporation

This research explored the possibility of making fertilizer at a laboratory from source separated and untreated human urine added to ash and lime by drying at low temperatures. A mixture of ash and lime (1:1) was used as drying agent and human urine was applied as undiluted and fresh. Ash and lime were chosen as drying agents for maintaining a pH > 10 during the drying process, which should inhibit urea hydrolysis in urine, and thereby urea should be retained in the drying agent. The drying technique was developed and drying capacity of the system was quantified; three specific temperatures (20 °, 35 °, 60 °C) and two airflow rates (1 L/min and 5 L/min) were used in the experiment. A mass balance for nitrogen in the system was obtained. It was evident from the experiment that urea can be retained by maintaining a high pH (>10). Urine drying at 20 °C was not a feasible option, since rate of evaporation was very low. The highest retention of inflow nitrogen at 35 °C and 60 °C were 74% and 54%, respectively, in the produced fertilizer. Reduced evaporation rate, flooding of urine over drying agent, and blockage in airflow influenced nitrogen loss and concentration of nitrogen in the final product.

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