The Folkewall is a construction with the dual functions of growing plants and purifying
greywater. It was designed by Folke Günther in Sweden.
Inspired by the "Sanitas wall" at Dr Gösta Nilsson's Sanitas farm project in
Botswana
Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...
, this technique makes an efficient use of space by fulfilling two essential functions: vertical plant growing and
purification of
greywater. This system is also known as a living wall or
green wall.
Design
The basic design is a wall of hollow concrete slabs, with compartments opening on one or both sides of the wall. The hollows are filled with inert material like
gravel
Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone.
Gravel is classifi ...
,
expanded clay aggregate
Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around in a rotary kiln. The yielding gases expand the clay by thousands of small bubbles forming during heating producin ...
,
perlite, or
vermiculite. It is designed to let the water
trickle
''Trickle'' is the second and most recent album from English trip hop band Olive.
History
Following the band's debut album '' Extra Virgin'' and a subsequent promotional tour, keyboard programmer Robin Taylor-Firth left the band. Also duri ...
over the longest possible treatment path along the length of the wall among the pebbles.
The water is brought in at the top, and percolates following a zig-zag pattern inside the wall. As it does so the plant roots grow among the inert material and extract nutrients from the water. A film of
beneficial bacteria grows over the pebbles, releasing the nutrients in the percolating greywater. At the bottom of the wall a container collects the purified water, which can then be used for non-
potable household use, 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 particularly suited for the Folkewall. Annual food crops are suitable, perennials like trees and shrubs should be avoided.
Greywater: The water feeding the plants in the wall must be free of
heavy metals
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Heavy metals are generally defined as ...
and/or unsafe
pollutants
A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...
, notably
human waste. This requires using source-separating toilets.
Advantages
* Better use of greywater: most of the evaporation happens through the plant's leaves, which makes the method especially useful in arid climates. The Folkewall makes use of this aspect.
* More efficient use of the area. For example in greenhouses or other glazed areas where a wall is used as a greywater purification device, it also works as a heat exchanger and buffer.
* Purification of the percolating water, so greywater can be used as irrigation water.
* In warm climates, the wall can be used on the sunny side to cool the building.
* Low-cost housing: the combined use of Folkewalls and source-separating toilets would "reduce the infrastructure cost by about 30%".
References
External links
Environmental design of human settlementsEngineered solutions for greywater purification and recyclingSocietal design for phosphorus recyclingBotswana tries two dryland farming methods
{{Permaculture
Bioremediation
Sustainable gardening
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