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Urinals Save the Day

June 16, 2015

My longtime friend and college roommate is one of four sons in his family.  His mother got so sick of cleaning the bathroom that served these inaccurate marksmen growing up that she installed a urinal.  It became so famous that all the boys in the neighborhood would find excuses to come use “the target that cannot be missed”, and to this day it’s the only urinal I know of that’s in a private residence.  His mother still credits it as the device that saved her sanity.

Now I propose that urinals have the power to save not just one parent’s plea to contain the pee, but the entire world’s struggle to manage its P.

In a previous post we’ve discussed the merit to source separation as an important step in P recovery from wastewater.  Urine contributes over half of the P found in wastewater (and three-fourths of the nitrogen).  Source separation is the idea of partitioning out the urine before it gets diluted and mixed with all of the other unpleasant things found in municipal wastewater, greatly increasing the efficacy of recovery technologies.  The question is how exactly we do that.

In 2007, Brad Allenby proposed a number of guidelines for making changes to global systems in the Environmental Science & Technology article Earth Systems Engineering and Management: A Manifesto.  The P cycle counts as an earth system under his definition because it is global in scale, highly integrated with other systems, and adapts over time.  Some of those guidelines include making dual function changes that allow for withdrawal, gaining stakeholder support by making decisions transparent, and making only controlled and incremental changes.

Using urinals as source separation instruments is a great way to better manage P in wastewater according to these principles.  Urinals capture the urine and can divert it to a separate waste stream, ideally to be processed locally for P (and N!) capture and reuse.  This would serve the dual purpose of reducing flows of wastewater collected at centralized wastewater treatment plants.  Even if the P recovery strategy did not work out, the infrastructure investment would still pay off due to lower operating costs at the plant.  Stakeholder support is also easy to build, as urinals are apparatus with which users are already familiar and comfortable.  Alternate source separation approaches available to date often require unfamiliar interaction from the user, which is likely to fail in such an intimate setting.  Of course employing urinals only can affect up to half of the human population (those with a Y chromosome), but that is consistent with making only controlled and incremental changes.

Employing urinals as source separation apparatus for improved P recovery is an effective first step to manage P as an earth system, and might just save the sanity of a few parents out there too.

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