Wed May 24th, 2006 at 05:28:30 AM EST
Yes, this is a diary about toilets.
The lovely city of Sneek in the province of Friesland has a remarkable premiere for the Netherlands: 32 new houses have been equipped with a new toilet.
Before you conclude that the rest of the Dutch are squatting across a hole in the ground, this toilet is a class apart. It's the culmination of various co-operating groups to demonstrate the DESaR concept: DEcentralised SAnitation and Reuse.
With this toilet in your house, you reduce 80 percent on water use, create fertilizer for agricultural purposes and in the long term you could even cook your meals on biogas extracted from what gets flushed down the toilet every day so casually.
From the diaries - whataboutbob
According to this folder (pdf!) from the ministry of Economic Affairs, the DESaR concept is based on the separation of different fluid flows used in a modern day house.
At first sight, only flushing is noticeably different from your ordinary toilet: instead of litres of water flushing your waste away, a vacuum pump - similar to those in aeroplanes - is now used. This alone reduces the amount of water significantly: from an ordinary 7 litres (!) per flushing to 1 litre, a reduction of 80 percent. However, flushing while sitting on the toilet seat I would not recommend.
But that's only where the story starts. "Black Water" (in the figure above depicted as "Brown Water") is the descriptor for the toilet waste that gets sucked to a central tank, which is located in the garage of one of the 32 houses. There, the waste material is brought to normal air pressures and a yeasting reaction starts - producing methane and CO2 which can be used to produce electricity. The first estimates predict that about 10 percent of the houses (so 3 out of a total of 32) can be sufficiently powered this way.
To the residue left in the tank, magnesium is added which sets off a chemical reaction that creates struvite, a common natural mineral which can be used as fertilizer. This is a known geochemical trick which was in the works for a while now, but a practical implementation was always hard as a technological transition was needed. DESaR seems to pull it off. "Struvinoirs" designed for restaurants whereby only the components in urine ("Yellow Water") are converted to struvite should also still be in the works, although I've not heard much about them lately.
The DESaR concept is a centralised sanitation - yet it is decoupled from the national sewer grid and in that sense it is decentralised. Because of that, and the severe reduction in water, the dissolved materials left in the remaining watery substance are now sufficiently concentrated that it becomes economically interesting to also extract those back. You should think of medicinal residues, hormones, toxics from cleaning materials. Scale matters: at about 500 houses also these materials can be extracted from the waste water. For the demonstration project this is therefore a bridge too far.
But bigger plans are in the making: the city council of Sneek wants to install these toilets also in the 1200 - 1500 houses still scheduled to be built.
DESaR reduces energy, water and nutrient use. It is economically interesting by turning the differences with the sanitation system needed to run an optimal, centralised sewage into an advantage. The demonstration in Sneek is the culmination of science research at the University of Wageningen, and the corporation of the city council with at least 5 commercial companies. It shows how decentralisation at the region level can have a decisive impact on how our western society moves away from a rampaging consuming society to a more durable one. A trend which is similarly visible in the United States where city councils and even States have put legislation in place that is already stricter than the Koyoto protocol on CO2 emissions.
And now I'm back to researching think tanks... I wanted a more thorough research on this subject, but this project has been making national headlines today so I'm overtaken by the ordinary press. I won't have it.