The Folkewall is a construction with the dual functions of growing plants and purifying

greywater Greywater (or grey water, sullage, also spelled gray water in the United States) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater fro ...

. 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, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

, this technique makes an efficient use of space by fulfilling two essential functions: vertical plant growing and purification of

. This system is also known as a living wall or

green wall A green wall is a vertical built structure intentionally covered by vegetation. Green walls include a vertically applied growth medium such as soil, substitute substrate, or hydroculture felt; as well as an integrated hydration and fertigation ...

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

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, expanded clay aggregate,

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, or

vermiculite Vermiculite is a hydrous phyllosilicate mineral which undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently; commercial furnaces can routinely produce this effect. Vermiculite forms by the weathe ...

. It is designed to let the water trickle 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 zigzag 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

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and/or unsafe

pollutants A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...

, notably

human waste Human waste (or human excreta) refers to the waste products of the human digestive system, Menstruation, menses, and human metabolism including urine and Human feces, feces. As part of a sanitation system that is in place, human waste is collect ...

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 settlements

Engineered solutions for greywater purification and recycling

Societal design for phosphorus recycling

Botswana tries two dryland farming methods
{{Permaculture Bioremediation Sustainable gardening Sustainable building Permaculture Sustainable technologies Organic gardening