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Description  |
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FIELD OF THE INVENTION
This invention relates to a closed ecological system, including humans,
which is completely isolated from the Earth's environment insofar as
transfer of matter is concerned. In particular, the invention relates to a
hydrological cycle within a closed homeostatic ecological system. The
water in the hydrological cycle supports the growth of a wide diversity of
organisms and is continuously recycled so that it remains usable.
BACKGROUND OF THE INVENTION
The Earth comprises a biosphere in which micro-organisms, plants, and
animals, including humans, exist in a more-or-less steady state. However,
the amount of pollution introduced into the environment of the Earth is
increasing, and the natural ability of the environment to dilute and
detoxify this pollution is becoming overwhelmed. The pollution of the
Earth's environment is leading to the extinction of many species of
wildlife and may prove to threaten the survival of all life forms on Earth
unless a means of detoxifying and recycling pollutants, created by man at
an ever-increasing rate, is found and implemented.
Moreover, as man ventures beyond the bounds of Earth and into space or to
the depths of the oceans, life support systems will necessarily have to be
transported with him. The resources that go with man will be limited and
not readily replaced. Therefore, it will be necessary to recycle these
resources and to prevent an accumulation of pollutants generated within
the closed environments.
It is desirable to provide a microcosm of Earth's environment, to study the
interaction of components of the environment and a variety of forms of
pollution that are generated on a daily basis, and to develop techniques
for influencing our environment in a positive manner. Such studies are
impossible, or difficult at best, in the open system provided on Earth,
since matter is exchanged between the Earth's and the study's
environments. This exchange results in a dilution of the pollutants that
are generated by the study and, also, introduces extraneous pollutants
from the surrounding atmosphere. To adequately test and evaluate the
procedures for coping with the pollution generated by day-to-day life, it
is desirable to provide a system that is completely enclosed. The enclosed
environment prevents matter from being exchanged between the study and the
Earth's environment. Since the environment is enclosed, and is of very
limited volume, matter within the environment has to be recycled and
detoxified, to prevent a rapid corruption of the air and water of the
enclosed environment or the need to continually dedicate an
ever-increasing portion of the enclosed environment to the storage of
useless trash.
Currently, a completely contained ecological system, referred to as
Biosphere 2, is being established near Oracle, Ariz. The system completely
encloses about one hectare of land and about 175,000 cubic meters of
space, isolated from the Earth's environment by an impermeable skin so
that no matter is transferred.
Biosphere 2 is intended to be as complete a simulation of the Earth's
environment as possible, and, therefore, the diversity of the
micro-environments that exist on Earth are duplicated within Biosphere 2.
As a result of this diversity of micro-environments, a suitable ecosystem
for the growth of the numerous organisms selected from these
micro-environments, including man, is also provided.
An essential component of the environment of Earth and, therefore,
Biosphere 2 is water. Water acts as a means of transporting pollutants or
nutrients away from a region where they are created, diluting them, and
carrying them to other regions, where they can be detoxified or used as
sustenance for other organisms. The aqueous components of Biosphere 2
consists of saltwater, freshwater, and potable water. Each of these water
systems provides a suitable micro-environment for the establishment of a
variety of organisms, including man. Nutrients/pollutants that accumulate
in one micro-environment, by the actions of the organisms present in that
micro-environment, can be transported to another micro-environment, where
they are removed by the different organisms that are present.
As well as distribution of nutrients and dilution of pollutants, water
circulation is necessary to aerate the water and prevent stagnation. This
water circulation therefore provides the general conditions suitable to
foster the growth of a wide variety of diverse organisms.
Water within Biosphere 2 is limited and, therefore, must be recycled. It is
important that water be appropriately treated, decontaminated, or purified
at each step within the complete water cycle. For example, saltwater must
be desalted before it is introduced into a freshwater micro-environment,
and waste water and sewage must be purified and decontaminated before the
water can be reused, thus preventing the possible accumulation and spread
of pathogenic organisms.
The treatment, decontamination, and purification of water in this closed
environment, therefore, provide a model for water purification and
recycling in the environment of Earth and for the establishment of
extraterrestrial or undersea colonies or other closed systems.
The operation of Biosphere 2 demonstrates the feasibility and efficiency of
such methodologies.
SUMMARY OF THE INVENTION
The present invention provides a method for establishing a hydrological
cycle in a closed ecological environment having a limited water supply and
isolated from the environment of Earth. The purity of the water in the
hydrological cycle is maintained by relying on, and establishing a
symbiotic relationship among, a variety of organisms established in
micro-environments within the closed ecological environment. Wastes
generated by the organisms of one micro-environment are removed by
organisms of a second environment and used as nutrients. The method
comprises the steps of: establishing colonies of a variety of organisms
derived from different micro-environments of Earth, within the closed
ecological environment; providing seasonal water supplies so that
micro-environments are established which simulate the environments of
Earth from which the organisms were selected; providing water
recirculation between the different micro-environments; and providing
means for purifying the water so that the quality of the recirculated
water simulates the water quality of the micro-environments of Earth from
which the organisms were selected.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will be better
understood when considered with reference to the following detailed
description and the accompanying drawings, where:
FIG. 1 is a schematic plan view of a closed ecological system;
FIG. 2 is a schematic longitudinal cross-sectional view through a
marshland/ocean biome;
FIG. 3 is a schematic longitudinal cross-sectional view through a
Rainforest/Savannah biome; and
FIG. 4 is a schematic block diagram illustrating an exemplary closed cycle
of water within the closed ecological system.
DETAILED DESCRIPTION
FIG. 1 shows the general layout of the micro-environments (biomes) within
Biosphere 2. Represented are an Estuary or Marshland region or biome 10,
an Ocean region or biome 12, a Rainforest region or biome 14, a Savannah
region or biome 16, a Thorny Scrub region or biome 18, a Desert region or
biome 20, and an Agricultural Zone and Human Habitat 21.
A qualitative description is given in the following sections which outline
the biomes in which water is used in Biosphere 2 and the various uses of
the water. It also describes an overall recycling plan of the water. Under
the heading "WATER CYCLE," a quantitative description of one embodiment of
a water balance of Biosphere 2 is given.
THE MARSHLAND/OCEAN BIOMES
The Marshland
The water in the Estuary region is freshwater at its source 22 and
increases in salinity as it flows downwards to its outlet 44 into the
Ocean 12. (See FIG. 2 for the relative elevation of the biomes and high
and low water levels.) The Ocean is saltwater, having a salts content
similar to Earth's oceans.
Varying salinity in the Marshland is created by the action of a tide which
simulates the tides that occur in nature. Such tides are important for the
establishment of aquatic ecosystems suitable for the growth of a wide
variety of organisms. To create the tides, saltwater is transferred from
the Ocean to the Estuary 34. Freshwater is also continually added to the
Estuary from the Freshwater Pond 22 at the source of the Estuary. The Pond
is at the highest elevation in the Estuary, at 8.49 meters relative to an
arbitrary datum for Biosphere 2. The freshwater flows downstream, i.e., to
a lower elevation, from the Freshwater Pond, to an Oligohaline Marsh 26,
then, in turn, to a Salt Marsh 28, to a Black Mangrove Marsh 30, to an
Oyster Bay 32, and finally, to a Red Mangrove Marsh 34, which is at the
lowest elevation in the Marshland, at 7.73 meters.
Saltwater is also continually added to the Marshland by pumping Ocean water
into the Red Mangrove Marsh, via a pump 36. The saltwater mixes with the
water in the Red Mangrove Marsh, and, as the water level rises, a salt
gradient is created. The Red Mangrove Marsh has the highest salt
concentration in the Marshland, and the Oligohaline Marsh has the lowest
salt concentration.
Each of the regions of the Marshland is separated by a wall, each of which
has a weir depression that is preset to retain the low-tide water level,
i.e., the depression in the wall is at a height that will determine the
low-tide level within each of the regions of the Marshland. The
depressions also allow water inflow into each of the regions when the
preset height or level of its weir depression is exceeded by the incoming
tide. For example, the low-tide level is 7.73 meters in the Red Mangrove
Marsh, 8.03 meters in the Oyster Bay, 8.11 meters in the Black Mangrove
Marsh, 8.18 meters in the Salt Marsh, and 8.26 meters in the Oligohaline
Marsh.
At high tide (spring tide) in the Marshland, the level of the water is 8.34
meters. At this high-tide level, water will rise through all the
Marshland, including the Oligohaline Marsh. It is only periodically at
"spring tide," when the water level is at its highest, that saltwater will
be introduced to the elevation of the Oligohaline Marsh.
When the Marshland is experiencing a spring tide of 8.34 meters, the Ocean
is at its low-tide (neap tide) level of 7.5 meters. At low tide in the
Marshland, the water level is 7.73 meters at the same time the Ocean is at
its high-tide level of 7.73 meters.
High tide in the Marshland is created by inhibiting the flow of water out
of the Marshland and by continually adding water to the Marshland. During
high tide, organic matter, nitrogen compounds, and other materials are
accumulated in the water from the organisms that grow in the Marshland.
When high tide in the Marshland has been reached, water is released from
the Marshland and flows into a "Crabwalk" 38 tidal capacitor. The high
nutrient level of the water from the Marshland is diluted in the Crabwalk
by mixing with Ocean water and by passing the water over algal scrubbers
before it is finally allowed to enter the Ocean.
When low tide in the Marshland is reached, the flow from the Marshland is
inhibited, and the water level is once again allowed to rise by pumping
from the Ocean.
The Crabwalk
The Crabwalk is a partitioned area which runs most of the length of the
Ocean and which is open to the Ocean at its end 40.
The dilution of the water released from the Marshland is important, since
it is high in compounds such as those containing nitrogen. While Marshland
water is a valuable source of nutrients for much of the wildlife in the
Ocean, very high concentrations of nitrogen compounds can prove toxic to
some of them. Therefore, it is important to lower concentrations of
nitrogen and other nutrients in Marshland water to acceptable levels.
Dilution of the nutrients in the water from the Marshland is achieved by
mixing water from the Marshland with the Ocean water present in the
Crabwalk. In addition, water from the Crabwalk is processed through
"scrubbers," which remove nutrients, toxic compounds, and particulate
matter from the water. Intakes 54 and outlets 56 for these scrubbers are
located in the Crabwalk.
The Tides
The flow from the Marshland, and therefore the tidal cycle, is regulated by
a water-level control device 44 located in the Red Mangrove Marsh,
adjacent to the Ocean. The water-level control device incorporates a
tiltable pipe, which, in one embodiment, has an open upper end through
which water from the Marshland can flow. The tiltable pipe is, in turn,
connected to a drain pipe which directs the flow of water from the
Marshland into the Crabwalk.
The tiltable pipe has a wide diameter which allows small animals, such as
some species of crab, to have access to both the Marshland and the Ocean.
Animals such as crabs require the different ecosystems that are
established in saltwater oceans and marshlands for feeding and also for
breeding. Therefore, it is important that these animals, if they are to
flourish, are able to gain access to both of these environments. The wide
diameter of the tiltable pipe allows animals such as crabs to crawl
through the pipe. In addition to allowing animals to crawl through the
pipe, the wide diameter of the pipe also results in a gentle flow of
water, rather than a "water-fall," through the pipe. A waterfall created
in the pipe could result in harm to animals that were crawling through
when the tides were changing and water was being reintroduced into the
Ocean.
Tides are created and regulated by the actions of a programmable stepping
motor, which can be programmed so that its action, in raising and lowering
the tiltable pipe, simulates natural tidal cycles over a 28-day period,
i.e., a lunar month. In natural environments, there are two high and low
tides within a lunar day (24 hours, 51 minutes). It is therefore desirable
to provide two high and low tides within Biosphere 2. In the Estuary, the
maximum water-level displacement between high and low tides is about 60
centimeters. However, as in natural environs, the tidal variation each day
is not at maximum displacement. Instead, the tidal displacement varies
throughout the month, with maximum high displacement (spring tide) and
maximum low displacement (neap tide) only being reached about once a
month. The tides at other times of the month are at lower displacements.
The tides within Biosphere 2 are set to simulate natural tidal displacement
throughout the 28-day lunar month. In addition to the requirement of two
tides per lunar day, it is desirable that the tides also resemble the
tidal amplitude changes or displacements of natural tides, which vary
throughout the lunar month. For example, at the beginning of the month,
the tidal amplitude can be close to its maximum of 30 centimeters above
the mean tide at high tide and 30 centimeters below the mean tide at low
tide. However, as the lunar month progresses, the amplitude may be as
little as zero displacement from the mean tide for the high or the low
tide. At the end of the 28-day lunar month, the amplitude would again be
at its maximum, completing the monthly cycle. The stepping motor is
programmed to simulate these desired tidal changes.
The changes in the amplitudes of the tides and the times of high and low
tides are desirable to foster the growth of tidal organisms, since the
"biological clocks" of these organisms are timed to coincide with these
natural rhythms. Duplicating this environment allows the organisms to
flourish by coordinating the rhythms of the organisms and promoting
natural symbiotic relationships between the organisms.
During the tidal cycle, water is being cycled from the Ocean to the
Marshland and back again. In addition, freshwater is continually being
added from the Freshwater Pond to the Marshland and, hence, to the Ocean.
To prevent the Ocean from "overflowing," and also to prevent the Ocean
water from being diluted with respect to its salt concentration, water is
removed from the Ocean and desalted. This water can then be used as a
freshwater supply, where needed, throughout Biosphere 2. The resulting
brine is returned to the Ocean.
As discussed above, the Crabwalk is a partitioned area which acts as an
"intermediate" separator tank and is used to treat nutrient- and
nitrogen-rich tidal-return flows from the Estuary before they enter the
Ocean. In addition to nitrogen, the Estuary water contains impurities and
particulate matter, all of which are preferably removed or reduced prior
to returning the water to the Ocean.
Dilution of the water returning from the Estuary is achieved by mixing
water from the Estuary with the Ocean water present in the Crabwalk. In
addition to dilution, water from the Crabwalk is processed through
"scrubbers," referred to as "algal turf scrubbers," which remove
nutrients, nitrogen, pollutants, and particulate matter from the water.
Intakes 54 and outlets 56 for the algal turf scrubbers are located in the
Crabwalk. Additional intakes 58 and 60 for additional sets of scrubbers
are also located in the Ocean and the Estuary, respectively. Outlets 62
and 64 for the scrubbers are located in the Ocean and the Estuary,
respectively. The algal turf scrubbers are located under the Thorny Scrub
region in a "basement."
The Algal Turf Scrubbers
The algal turf scrubbers comprise beds of algae which act as biological
converters, converting nutrients or pollutants in the Ocean, Estuary, or
Crabwalk water into complex organic matter that can be used as compost,
fodder for animals, or as a food supplement for humans. The algae extract
nutrients and nitrogenous wastes from the water.
The algal bed is a flat, mesh screen that provides an anchor and support
for the growth of algae. Other essential growth requirements for the algae
are aeration and agitation of the water to distribute nutrients, to remove
any waste products generated and to minimize shadowing of the algae by
other algae in the algal bed.
In natural growth environments, these requirements are met by the actions
of waves. In the algal turf scrubber, these requirements are met by the
manmade generation of a wave across the face of the algal bed. This smooth
wave action across the entire face of the algal bed promotes even growth
of the algae across the entire algal bed and inhibits the occurrence of
overgrown clumps of algae in isolated areas.
Dissipation of the wave is required to prevent a reflected wave from
traveling back across the algal bed, disrupting a new wave traveling down
the algal bed. In addition, the wave is dissipated to prevent excessive
agitation of the water at the downstream end of the algal turf scrubber
and stirring up of particulate matter. To prevent a reflected wave, a wave
interceptor is provided at the downstream end of the algal bed. Water from
each algal turf scrubber is returned to the Crabwalk, Marshland, or Ocean,
as appropriate.
A settling tank in the algal turf scrubber provides a large volume of
"still" water, so that particulate matter suspended in the water may
sediment, under gravity, and can be removed from the water before it is
recirculated back to the Crabwalk, Marshland, or Ocean.
Artificial lights over the algal turf scrubbers are provided. Since algae
are photosynthetic, light is an essential requirement for their growth.
Algae carry out photosynthesis, a reaction in which carbon dioxide and
water are converted to sugar and oxygen, in the presence of light. This
reaction confers on the algae the ability to generate oxygen and to reduce
the ambient levels of carbon dioxide.
In addition to their photosynthetic ability, many algae are also capable of
fixing nitrogen or of utilizing nitrogen in the form of free nitrogen,
nitrogen oxide, hydrazoic acid, hydrogen cyanide, and other nitrites.
Therefore, much of the nitrogen can be removed from the water by the
establishment of colonies of algae that are capable of fixing nitrogen.
Once an algal turf is established and grown, it must be harvested.
Harvesting of the turf is preferably performed before the turf is
overgrown by larger macro-algae. Harvesting of the algal turf can be
accomplished by simply scraping the surface of the screen.
After harvesting of the algal turf, immediate regrowth of the algal turf
will occur in the cleared screens, since the screens are sufficiently
coarse to retain a portion of the filamentous algae after harvesting. The
remaining filamentous algae will reestablish colonies in the mesh screens.
The period of growth and the subsequent need for harvesting are dependent
on the many variables that determine the rate of growth of the algal turf,
such as exposure to and intensity of the light, temperature, surge action
of the wave, and, hence, the flow rate of water across the screens, the
screen size, and the availability of nutrients. Each of these conditions
may be varied to promote the growth of a particular species of algae or to
improve the growth rate of all the algal colonies that are established in
the algal tray.
The Ocean
The Ocean is divided into a deep "ocean" region 48 and a shallower "lagoon"
region 50 by an intervening Coral Reef 52. A small portion of Coral Reef
is included in the Ocean for its role in the carbon cycle and to provide a
suitable habitat for some of the plant and animal species which live in
the Ocean. About 250 species of fish are also included in the Ocean. The
fish excrete ammonia into the water in their wastes. Naturally-occurring
microorganisms convert the ammonia to nitrates, which are then available
as nutrients for algae.
In the Marshland, tides are used to recirculate water, nutrients, and
pollutants. Similarly, recirculation of water in the Ocean is achieved by
the action of waves. Waves induced along the surface of the Ocean by a
wave generator 46 are propagated along the surface of the Ocean and may
spill over the Coral Reef and continue beyond, into the Lagoon region.
The Wave Generator
The wave generator 46 is installed adjacent to an edge of the Ocean. The
wave generator includes a water elevator positioned next to the Ocean, a
blower for exhausting air, and an air buffer connected between the blower
and the water elevator. The water elevator includes a water-lift chamber
rising above the surface of the Ocean, an opening extending below the
surface of the Ocean for exchanging water between it and the chamber, and
air inlets and outlets for respectively admitting air into and exhausting
air from the water-lift chamber.
Connected between the blower and the water-lift chamber air outlet is an
air buffer, through which air is drawn by the blower from the chamber.
Valves periodically open and close the air inlet and air outlet of the
water-lift chamber so that, when the air inlet is closed and the air
outlet is open, water is raised in the water-lift chamber. When the air
outlet is closed and the air inlet is opened, water drops within the
chamber and is expelled through its underwater opening, inducing a wave
along the surface of the Ocean.
The blower operates continually, and pressure fluctuations, which tend to
be induced by the periodic opening and closing of the valves, are smoothed
out by the air buffer before they reach the blower. The air buffer
includes a first air chamber pneumatically connected to the air intake, a
last air chamber pneumatically connected to the water-lift-chamber air
outlet, and at least one intermediate air chamber pneumatically connected
between the first and last air chambers through openings in the
inter-chamber partitions.
The Desalting Process
Water in the Estuary is continually being added from the Freshwater Pond at
its source. This water eventually flows into the Ocean. Water, therefore,
has to be continually removed from the Ocean to prevent it from filling up
and overflowing, and also to prevent dilution of the salt concentration of
the Ocean. However, since the water from the Ocean is salty, it must be
desalted before it can be reused in other areas of Biosphere 2. The
desalination of the Ocean water is achieved by a low-pressure,
low-temperature distillation unit. The desalted water from the Ocean is
then used for watering crops, as a partial supply of fresh water to the
headwaters of the Rainforest biome, or other uses where freshwater is
required. The brine which results from the desalting process is returned
to the Ocean.
THE RAINFOREST/SAVANNAH BIOMES
The Rainforest
Rainforests are derived from tropical zones and are characterized generally
by their evergreen canopy and warm and moist climates. Rainforests, in
nature, generally receive over 250 centimeters of rainfall per year. The
rainfall is delivered in a seasonal downpour during the monsoonal months.
The rainfall in the Rainforest of Biosphere 2 varies seasonally over a
four- to six-month period, and the annual precipitation accumulations
range from about 150 to 250 centimeters. A system of overhead pipes
delivers a spray, to simulate rain. Daily rainfall in the Rainforest biome
can vary from zero to two centimeters per hour.
Freshwater is introduced into the Rainforest biome as rain and mist onto a
Sphagnum Moss region 66 at an elevation of about 20.12 meters (see FIG.
3). The water seeps from the Sphagnum Moss into a pond, "Little Tiger
Pond" 67, which is at an elevation of about 19.61 meters. The seepage from
the moss is relatively acidic, approximately pH 5.5 to 6.0, which results
in a slightly acidic pH of the water in Little Tiger Pond. Additional
water is added to Little Tiger Pond from an Ocean water desalting plant
and recycled from a Splash Pond 70.
The water from Little Tiger Pond flows over a Waterfall 68 and into the
Splash Pond. The Splash Pond is at an elevation of about 14.94 meters. The
Splash Pond provides "spray" moisture to ferns and plants which are grown
in areas adjacent to the Waterfall, maintaining the high-humidity
environment that they require for their proliferation.
Water from the Splash Pond cascades into "Tiger Pond" 72. The elevation of
Tiger Pond varies from a low of about 13.56 meters to a high of about
14.63 meters. This approximately-one-meter change occurs as a result of a
moving control gate or weir 73 which can be raised or lowered, as
required, to simulate seasonal flooding in "Crystal Creek" 78. The rate of
rise or decline in both Tiger Pond and Crystal Creek is approximately four
centimeters per week. For a six-month period, during the wet season, the
water levels are rising, and for six months, during the dry season, the
water levels are declining.
To supplement the flow and volume of water in Tiger Pond, water is recycled
to Tiger Pond from downstream. The water is supplied by the action of
recirculation pumps 74, which draw water from a storage tank 76 at the
bottom of a downstream creek, Crystal Creek. A portion of this water is
also discharged into the Splash Pond. The recirculation of the water in
Tiger Pond dilutes the higher acidity of the waters flowing out of Little
Tiger Pond.
The water from Tiger Pond is discharged downstream into Crystal Creek.
The Crystal Creek water levels vary from an elevation of about 12.8 meters
to about 13.87 meters. This approximate one-meter difference is a
simulation of seasonal rates, and the water levels are increased for six
months, then decline for six months. These fluctuations in the water
levels are controlled by a movable weir.
A movable weir is located on the storage tank 76 that intercepts the
water-flow from Crystal Creek. The storage tank is a box-like structure
and is constructed with a vertical opening on one of its faces. Water
flows into the vertical opening, and the water level in Crystal Creek is
maintained at the level of the bottom of the opening.
To vary the water level in Crystal Creek, the level of the vertical opening
in the storage tank is raised. Raising of the vertical opening is achieved
by raising a gate which is positioned to cover and slide over the vertical
opening. At the low water level, the gate is in its lowest position. At
the high water level, the gate is in its raised position, and water is
retained in Crystal Creek until the new, raised level is achieved and the
water level is raised to the high water level. When the high water level
is reached, water again flows into the storage tank.
A water flow-through device is also mounted on the gate of the storage
tank. This flow-through device directs water from Crystal Creek to a
Savannah Stream 82. The flow-through device comprises a small-diameter
tubing which restricts the a | | |
