Question

Phosphorous (P) is an indispensable nutrient in food production. According to the estimates, mineral
phosphorous resources will end up within 50 years and consequently new sources of P has to be found.
A human excretes 2,2 g of phosphorous (P) per day on average. In conventional wastewater management
system, with flushing toilets, only 1 % of the excreted P is recycled into food production. Dry toilets
could be used as an alternative to the conventional flushing toilets and they can make it possible to recycle
80 % of P directly into food production.
a) Estimate the increase in amount of recyclable P in a country of 5,5 million persons in one year, if alternative
dry toilets would replace the conventional flushing toilets.
b) Calculate the mass percentages of P and N in struvite, (NH4MgPO4).