That’s a rhetorical question, by the way. But it seems appropriate to introduce a report of research carried out by aquatic scientists in Switzerland into the possibility of extracting useful nutrients from pee.
The basic idea, according to Tove Larsen and her colleagues at EAWAG in Dübendorf, is simple: urine accounts for only 1% of the total volume of wastewater, but it contains up to 80% of all the nutrients. If the urine were processed separately, water treatment plants could be reduced in size and the nutrients recycled.
Here’s a nice little factoid to illustrate what the researchers mean. Every year the average family of four pisses away some six kilogrammes of concentrated phosphorus. This is one of the things that cause discomfort when peeing. The late great composer Frank Zappa got it from the toilet seat when it jumped up and grabbed his meat. But with nice clean middle class families the cause is phosphates in urine concentrated as a result of not drinking enough fluids.
Adopting urine source separation technology (“NoMix”) on a large scale would be particularly useful in countries where wastewater treatment cannot keep up with the rapid pace of urbanisation and industrialisation. But the researchers warn that there are a number of technical, infrastructural, economic and environmental obstacles to overcome before the technology can be implemented.