BioHome was a small facility created by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

in the late 1980s that could support one person in a fully functional habitat. One of the influences on the project was the results from data obtained on the 1973 Skylab 3 (SL-3), where a total of 107

VOCs Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a ...

were

offgassed Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (which ...

by synthetic materials that composed the SL-3. However, the study of

indoor air quality Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort, and well-being of building occupants. Poor indoor air quality has been linked to sick building syndrome, reduce ...

was not the only focus of the project, as it was a part of research into closed

ecological Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

life support Life support comprises the treatments and techniques performed in an emergency in order to support life after the failure of one or more vital organs. Healthcare providers and emergency medical technicians are generally certified to perform basic ...

systems. The facility was still in use as of March 5, 2005, and has paved inroads into creating self-supporting life support systems.

Construction

Construction of the BioHome concluded in 1989 and construction materials included synthetics which gave off the aforementioned VOCs. The BioHome itself resembles a

mobile home A mobile home (also known as a house trailer, park home, trailer, or trailer home) is a prefabricated structure, built in a factory on a permanently attached chassis before being transported to site (either by being towed or on a trailer). Us ...

in size where it contained a living area and treatment facilities for human waste and air. While not completely air-tight, such as the

Biosphere 2 Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the univers ...

structure, the structure was engineered for maximum air and energy confinement. This was unsurprising, given that the interior walls were composed of molded plastic panels with 30 cm of fiberglass insulation. The BioHome had living facilities that could support one person and foliage plants were placed throughout the structure, aiding in air purification. In addition to the plants, a prototype fan-assisted plant filter was installed; the filter had the removal capacity of 15 standard potted plants. The BioHome was equipped with monitoring ports for the detection of VOCs, which were measured using

mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is us ...

gas chromatograph Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...

equipment. In experiments regarding

wastewater treatment Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environme ...

, the facility was outfitted with PVC piping and

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

equipment.

Usage

The BioHome was used for a variety of experiments into, and including:

Wastewater treatment

In its nascence, the BioHome focused on alternative, non-chemical

sewage treatment Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding envir ...

methods utilizing non-edible plants of aquatic disposition. The aquatic and semi-aquatic plants were chosen based on their previously known abilities for waste treatment. Another usage for the plants used in the wastewater treatment included its implementation as

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...

, which was feasible as the plants grew as more sewage was introduced.

Means

All waste material, such as feces and

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...

, were routed through PVC pipes, punctured so that the root systems of aquatic / semi-aquatic plants could be inserted. At different points of the flow, the water was studied (although those specific results are unavailable at this writing). Ensuring total eradication of microorganisms, the processed water was subjected to

ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

. The processed water is subsequently used as toilet and plant water, though not directly for human consumption.

Plants used

Plants, or more accurately, the root systems of aquatic plants found to have a filtering effect include

bulrush Bulrush is a vernacular name for several large wetland grass-like plants *Sedge family (Cyperaceae): **''Cyperus'' **'' Scirpus'' **''Blysmus'' **''Bolboschoenus'' **'' Scirpoides'' **'' Isolepis'' **'' Schoenoplectus'' **'' Trichophorum'' * T ...

reed Reed or Reeds may refer to: Science, technology, biology, and medicine * Reed bird (disambiguation) * Reed pen, writing implement in use since ancient times * Reed (plant), one of several tall, grass-like wetland plants of the order Poales * ...

soft rush ''Juncus effusus'', with the common names common rush or soft rush, is a perennial herbaceous flowering plant species in the rush family Juncaceae. In North America, the common name soft rush also refers to '' Juncus interior''. Distribution '' ...

and water iris. As explained b
Wolverton

When sewage is slowly filtered through an aquatic plant root filter system, complex biological processes take place during wastewater treatment and purification. The
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
relationship that is normally established between the plant roots and microorganisms living on and around these roots is very complex and important in the wastewater treatment process... This process not only removes
organic chemicals In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...
, but is also thought to contribute to the reduction of other polluting substances including pathogenic
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
and
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...
es. It has been shown that roots of aquatic plants such as bulrush, reed, soft rush and water iris excrete substances that can either partially or completely kill pathogenic bacteria while not harming beneficial bacterial. The aerobic zone around the aquatic root system can also support, in addition to bacteria, the growth of large numbers of
protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...
which feed on bacteria, viruses and particular
organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
.

Harvesting drinking water

Water suitable for human use was extracted from the condensate from three sources: dehumidifier units,

air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...

, and plant leaves. In fact, plant leaves proved to be a major, consistently reliable source of

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous pha ...

s. The condensate was run through ultraviolet equipment to ensure its safety.

Crop growth

Crops were grown in the hydroponic sections of the BioHome, comprising edible plants (

squash Squash may refer to: Sports * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (professional wrestling), an extremely one-sided match in professional wrestling * Squash tennis, a game similar to squash but pla ...

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

es and other organics) and non-edible plants, which were an essential part of the

air purification An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating ...

process. Compost made from wastewater treatment plants was used effectively as a

growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...

.{{cn, date=May 2014

Air purification

The living areas of the BioHome were teeming with plant foliage, the purpose of which was to purify the air of

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

. As a result of the experiment, it was also found that the plants purified the air of synthetic offgases, such as those emitted from

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) a ...

and organics. In essence, the plants established and maintained indoor air quality.