Calculation

Nutrient Recycling Potential Calculator for Households Using Integrated Decentralised Wastewater Treatment Systems

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The following calculator provides the user with the opportunity to estimate the potential fertilisation area, if faeces and urine from a household are applied. The recommended integrated decentralised wastewater system would use this fertilisation potential for non-food plants and long term soil enrichment.

Nutrient Recycling Potential Calculator

Faeces Application:

Faeces are rich in phosphorous (P), potassium (K) and organic matter and can contribute to non-food crop production both by their fertilising effect and by their soil-improving effect. The proportion of nitrogen that is in mineral form in faeces varies largely between the different purification strategies and can be lost in form of gases. Therefore, only the Phosphorus-fertilisation of Terra Preta Sanitation compost is considered.

Please find more information in this literature review.

Please Enter The Number of Household Members:

Yearly Faeces Production
per Household (kg/a):

Yearly Phosphorus-Fertilisation Area of Terra Preta Sanitation (TPS) compost per Household (m2/a):

Yearly Organic Content Supply Area of  TPS compost per Household (m2/a):

Urine Application:

RUVIVAL Urine Application Calculator

Urine contains four important nutrients for plant growth: nitrogen (N), phosphorus (P), potassium (K) and sulphur (S). The direct application of nutrient-rich sanitised urine to the soil for non-food crops provide the opportunity to recover the nutrients and also reduce the use of fertilisers. The urine application calculator tool developed by RUVIVAL calculates the potential urine fertilisation area of a household based on the yearly production of urine.

Click On the Calculator Icon to Access the Urine Calculator

More information about urine application can be found here.

Background of the Calculator

Excreta ValuesValuesUnit 
Daily Faeces Production per Person140g/d(grams per day)
Yearly Faeces Production per person51.1kg/a(kilograms per year)
Yearly Amount of Nitrogen in Faeces per Person550g/a(grams per year)
Yearly Amount of Phosphorous in Faeces per Person183g/a(grams per year)
Phosphorus Fertlisation of TPS Faecal Compost per person900m²/a(square metre per year)
Yearly Organic Content Supply Area of TPS compost per person4.5m²/a(square metre per year)

According to Jönsson et al. (2004), the potential yearly amount of nitrogen and phosphorus in faeces per person in Sweden is 550 g/(a·person) of nitrogen and 183 g/(a·person) of phosphorus. The yearly amount of nitrogen and phosphorus in faeces per household is calculated from the potential yearly amount of nitrogen and phosphorus in faeces per person multiplied by the number of household members.

According to research done in Tanzania by Krause et al. (2015), total phosphorus in TPS compost is found to be 3.6 times the total phosphorus in faeces compost. The yearly faeces fertilisation area of TPS compost per household is calculated from the potential yearly fertilisation area of faeces per person (900 mfor phosphorus) multiplied by the number of household members. The yearly organic content supply area of TPS compost per Household is calculated from the potential yearly organic content supply area of TPS compost per person (4.5m2 /(a·person)) multiplied by the number of household members.

This calculator takes as a reference point the research done by Jönsson et al. (2004), the amount and nutritional value of faeces and urine are based on the data of the Swedish population. It is important to note that amount and nutritional values of faeces and urine are subjected to variation in different regions of the world and are highly dependent on the nutrient uptake and diet of the population. The nutritional value of wastewater streams improves the quality of the urine and faeces to be used as fertilisers for non-food crops.  Therefore, the provided results should only be considered as a reference point when referring to the potential for nutrients recycling in integrated decentralised wastewater treatment.

The values used in this calculation tool are based on the following studies.

Jönsson, H, Richert, A, Vinneraas, B & Salomon, E 2004, Guidelines on the use of urine and faeces in crop production, EcoSanRes Publication Series, 2nd edn, Stockholm Environment Institute, Stockholm, Sweden.

Krause, A, Kaupenjohann, M, George, E & Koeppel, J 2015, ‘Nutrient recycling from sanitation and energy systems to the agroecosystem- Ecological research on case studies in Karagwe, Tanzania’, African Journal of Agricultural Research, vol. 10, no. 43, pp. 4039–5.

Nutrient Recycling Potential Calculator for Households Using Integrated Decentralised Wastewater Treatment Systems by Usama Khalid and Ruth Schaldach is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

 

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