The 'household-sized' wetpark


- a small greywater purification system


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The water/sewage grid becomes unnecessary

With source-separating toilets and local purification of greywater, a household will be freed of the need for external sewage system and water services. Urine and faeces is used as a nutrient source for the local agriculture, and the water can be recycled.

With the addition of rain water to the system, the household will not only be self-sufficient with water, it will be a net producer of clean water.

Need for small-size wetparks

With an increasing appreciation of the 'wetpark' system at the Technical University of Kalmar, the question was taken up whether it is possible to make a similar system for only a few people.

Such a system was designed and built in Rönås, Sjöbo, Skåne, Sweden during the spring 2003. (The link goes to ViaMichelin for a map. If you don't have a Swedish keyboard: write Kristinehov, Europe.)

The site

Below is a diagram of the site. Click on the different parts of the diagram to see pictures and details. Follow the arrows for water and material flows. This is a great improvement over the traditional management system, but it should be noted that this system doesn't constitute a circulation of phosphorus unless the people involved are mainly fed from the products of the farmland.

Click on the picture to see details

The site before building. The wetpark will be situated in the front of the picture.

Principles of construction.

The designer made calulations of the plant according to the site, rainfall, evapotranspiration and the attached population

Construction

After the digging of the cavity, it is evened out with sand, covered with plastic sheets and a bentonite matting. The latter is very heavy and it is a hard work to put it on the right place with the correct overlapping.

Finished

The previous three-chamber cesspool was used as a separator for any possible sludge in the greywater from the house. In this, the rainwater from the roofs is also collected.

The finished wetpark from the inlet side. A large part of the water is inside the shore zones. By that, the plants (yet to come) can take up the nutrients and enhance microbial action.
The water level is still rather low due to a few months of drought.

The inlet is a concrete pipe with a bottom. Close to the bottom are holes for the water to enter the first shorezone.

Although the water is only greywater, it is rather turbid.

The wetpark from the outlet side, almost from the same angle as the first picture.
The outlet. It is easy to see that the water already is much cleaner. (Touch the water in the right picture!)

 

The linchpin -- no MIFSLA!

In order to avoid the MIFSLA trap, a source separating toilet system must be used. The main difference from an ordinary toilet is that the big water tank is missing. No more Niagara after peeing!
However, a small flush is used to dilute the urine to a level that no crystallization will occur in the pipes.

In the cellar under the toilet faeces are collected in a jar equipped with compost worms. The air is blown out from the jar (and the bathroom!) with a fan.through the metal pipe.
No more foul smell in the bathroom!
Behind is the grey pipe for the urine.
The urine (yellow pipe) flows to the urine collection well (common for the pigs and the humans at this site). From that, it is pumped up to a larger urine tank for transportation to farmland.

An article for the EcoEng Newsletter, 2003b

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Updated:
2013-01-06