Folkewall

Inspired by Dr Gösta Nilsson's "Sanitas wall" at the Sanitas farm in Botswana, this technique makes an efficient use of space by fulfilling on its own two essential functions: a mutually beneficial system allies vertical plant growing and the purification of greywater.

Design

The basic design is a wall of hollow concrete slabs with compartments opening on one or both sides of the wall. The hollow parts are filled with inert material like gravel, LECA-pebbles, perlite or vermiculite. In order to let the water trickle over the longest possible treatment path, plastic sheets are laid horizontally at intervals along the length of the wall between the pebbles.

The water is brought at the top, and percolates following a zig-zag pattern throughout the inside of the wall. As it does so it feeds the plants which purify it in the same process. The plant roots grow through the inert material and extract nutrients from the water. A film of beneficial bacteria grows over the pebbles, releasing the nutrients in the percolating organic material. At the bottom of the wall a container collects the purified water, which can then be used for non-drinking house uses or for watering the garden; or it can be returned to the top of the wall.

Other considerations

"Plants used": since the harvesting of the plants is a part of the purification process, fast growing, herbaceous crops are specially suited for the Folkewall. Perennials like trees and shrubs should be avoided.

"Greywater": The water feeding the plants in the wall must be devoid of heavy and/or unsafe pollutants notably blackwater. This requires using source-separating toilets.

"Pay-back period": Gus Nilsson calculated for his walls at Sanitas farm, Gabarone Botswana, that the growth and selling of tomatoes on the wall would pay the entire erection cost of the wall in three years.

Advantages

* Better use of the water: most of the evaporation happens through the plant's leaves, which makes the method specially useful in arid climates. It is this aspect Gus Nilsson makes use of.
* More efficient use of the area, for example in greenhouses or other glazed areas.
* In a greenhouse where the wall is used as a greywater purification device, it also works as a heat exchanger and -buffer.
* Purification of the percolating water, if greywater is used as irrigation.
* A wall x by x m2 is sufficient to purify greywater for 3 (or 4) people. The water can be reused in the house for non-drinking purposes, or to water the garden.
* In warm climates, the wall can be used as building material on the south side. This will cool the building.
* Low-cost housing: the combined use of Folkewalls and source-separating toilets would reduce the infrastructure cost by about 30% [http://www.fastonline.org/CD3WD_40/JF/JF_OTHER/SMALL/Growing%20wall%20-%20Water.pdf] [http://www.iobborg.net/drupal/node/view/491] .

Background

The Folkewall [ [http://www.holon.se/folke/projects/openliw/openlev_en.shtml Folkewall] ] has been designed by Mr Folke Günther [ [http://www.holon.se/folke/cv/Eng/Biography/short.shtml Folke Günther] ] in Sweden. Mr Günther is managing director of [http://www.holon.se/folke/holon/Holon_en.shtml Holon Ecosystem Consultant] , a firm working on [http://www.holon.se/folke/lectures/Ruralisation-filer/v3_document.htm ecological clearance and design of human settlements] , [http://www.holon.se/folke/projects/vatpark/Kth/guntha.shtmlecological engineered solutions for greywater purification and recycling] , [http://www.holon.se/folke/kurs/Distans/Ekofys/Recirk/Eng/phosphorus.shtml societal design for nutrient recycling] , precautionary remedial measures for decreased availability of energy, and Carbon dioxide sequestration by soil improvement with charcoal on agricultural land, also called Terra preta.

In 1998 he visits [ [http://www.gov.bw/cgi-bin/news.cgi?d=20031201&i=Botswana_tries_two_dryland_farming_methods Botswana tries two dryland farming methods] , article in Botswawa government's site - Dr Gösta Nilsson's work.] Dr Gösta Nilsson in Gabarone, Botswana. Dr Nilsson's place, Sanitas farm, is one of Botswana's key actors in micro-irrigation and rainwater harvesting. There Mr Gűnther becomes inspired by his type of vertical growing. Between 1998 - 2001 he invents and studies different types of materials. In 2002 a Folkewall is put up at [http://www.stofair.se/nordiskatradgardar/ The Gardening Exhibition i Älvsjö] (11 - 14 April 2002) with the [http://www.ecotopia.com/schoolhouse/report.asp?id=1775 Swedish Pernaculture Association] . This is also the year when the first Folkewall models are made (pictures by Olle Skoglund).

References