Dry toilets “in action” in UNESCO-IHE building

Dry toilets “in action” in UNESCO-IHE building

Practice what you preach, or in this case apply what you teach. One of UNESCO-IHE Institute for Water Education’s topics is ecological sanitation (ecosan), which includes how to save water, how and why to separate urine and solid waste at source and return nutrients contained in human excreta to agriculture. The question arose: “Could we practise what we preach here in our building?”

No sooner said than done! The first 11 water-free urinals and one dry urine-diversion toilet have been installed in the building, with the financial support of the City of Delft and inputs from the two providers Uridan (Denmark) and Ecosave (The Netherlands). The 350 UNESCO-IHE building residents (staff, PhD researchers and Master of Science purchasers) account for around 3800 m3 of water use in a typical year, of which about 50% is used for sanitation -the old urinals used about 4-6 litres per flush- and the rest in the laboratories and kitchen. With the water-free urinals UNESCO-IHE saves about 17% (or 650 m3/year). At the moment, the urine is discharged to the sewer, but it is also possible to collect the urine and use it as a nitrogen-rich fertiliser. This is already being done at many locations around the world.

A unique design feature with these urinals is that there is a blocking liquid in a small cylinder just below the outlet from the bowl. This blocking liquid is made from plant oil; urine passes through it, but the odour from the sewer system does not. One filling of blocking liquid costs €18 and lasts about 7,000 visits.

So, why pollute 5 litres of clean drinking water with 0.25 litres of urine (from one visit to a urinal) just to flush it away? How much drinking water do you waste? This is no longer necessary.