Sample of All FAQs (Helpie FAQ)
Helpie FAQ
- What about pharmaceuticals
Contaminants
- Cross contamination risk from the feces to urine during excretion and collection in urine-diverting toilets
- Refer to Nathnael’s thesis on UV radiation to remove pharmaceuticals and pathogens – just say that we’re really looking into it, it’s possible (UV and other oxidation methods), redirect to say it’s more of a problem with pharmaceuticals in drinking water, when urine is spread on fields pharmaceuticals get degraded naturally by UV radiation from the sun https://www.sciencedirect.com/science/article/pii/S0043135423006577
- OMP = organic micropollutant
- “The energy demand for removal of OMPs in water was <1500 J m-2, but for removal of OMPs in urine at least 10-fold more energy was needed. A combination of photolysis and photo-oxidation can explain the degradation of OMPs during UV treatment. Organic substances (e.g. urea, creatinine) likely inhibited degradation of OMPs in urine by competitively absorbing UV-light and scavenging free radicals. There was no reduction in the nitrogen content of urine during treatment. In summary, UV treatment can reduce the load of OMPs to urine recycling sanitation systems.”
- What is the capacity of the urine concentrator?
1 liter of urine is dried to 0,04 liters or 40 grams (concentrated 25 times).
Our first concentrator has a volumic capacity of approximately 300 L urine and requires a minimum of 600 Wh/L of urine.
- Why do you dry the urine instead of using the liquid urine?
Untreated urine has a very low nutrient concentration which means farmers would have to add incredibly large volumes to reach the needed nutrient amounts for optimal crop growth. The three macronutrients needed for crops are nitrogen (N), phosphorous (P) and potassium (K) = NPK.
NPK in untreated urine = 0.6% N – 0.07% P – 0.16% K.
Our dry urine fertilizer: 15% N – 2% P – 4% K. This high NPK concentration is due to that we remove the water from the urine, concentrating it 25 times into a dry, nutrient rich powder. We then grnaulize it, enabling farmers to use the granules in their usual fertilizer spreading machines. With liquid urine, this would not be possible – meaning farmers would have to buy new equipment.
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