Urinals for water savings and nutrient recovery: a feasibility study

Abstract

This research investigates the feasibility of implementing waterless urinals at a public university in Cape Town, South Africa. Two analytical approaches were adopted to assess the feasibility of the proposed systems: a social study in the form of an online survey and an economic evaluation of four separate water savings and nutrient removal systems. In terms of the online survey, 87% of respondents claimed they would use urine- diverting technology and 79% stated they would eat food that was grown using urine-recycled phosphorus as fertilizer. It was found that merely reducing the number of times a urinal could be flushed to 3 times per day could save approximately 18 ML of water annually. Additionally, the University of Cape Town requires 3 600 kg of fertilizer for its sports fields, while the urine collected in waterless systems has the potential to produce 6 700 kg of fertilizer. This work has shown that a significant amount of water can be saved by installing waterless urinals in public institutions such as a university. It also shows that there is potential to recover valuable resources from our ‘waste’ streams, thus closing various nutrient cycles through on-site fertilizer production.

Keywords: fertilizer, nutrient recovery, phosphorus, urine, water savings