The Water Subsystem collects wastewater from all possible sources, recovers and transports potable water, and stores and provides the water at the appropriate purity for crew consumption and hygiene as well as external users.
Interfaces: Air, Biomass, Food, Thermal, Waste, Crew, Cooling, EVA Support, Human Accommodations, ISRU, Integrated Control, Power, Radiation Protection
Water in the water cycle comes mainly from four sources:
1. Both plants and animals transpire water vapor into the air.
2. Animals produce urine (waste water).
3. Humans use water for washing, which produces gray water.
4. Water storage bodies will evaporate water from air water interfaces
Typical water usage breaks down as follows:
human cooking/consumption: 75 l/day
bathing:400 l/day
garden: 25 l/day
Transpiration is largely a factor of temperature and lighting. In mid latitudes on Earth, most plants are only able to use 1/4 to 1/2 of the summer insolation that impacts their leaves. Above this level actually slows growth and results in heat, which the plant must shed by evaporating water.
Water Purification
Water Storage
Cistern size
Sand will store water about 50% of its bulk and water in between the sand grains is is less likely to evaporate than in an open air pond. Water can also be used for (energy storage)).
Gray water and urine are mixed and channeled into grow beds via bottom-laying perforated pipe, where various micro-organisms, fungi, and higher plants break down and convert soap oils and waste fats, food particles, dead skin, and urine into an organic food supply and oxygen. The more waste is treated by the root systems of the plants, the larger the plants grow. Fresh water is produced via plant transpiration and soil bed evaporation and is condensed out of the air by a ground loop (air well) dehumidifier and the water collected goes into the clear water tank to be UV or O3 sterilized for potable use. As the microbes, fungi, and plant roots are proven to be very efficient in filtering the organics and nutrients out of water, any water which makes it from the gray water entrance point (high point of the bed) can be stored in the white water tank located at the lowest end of the grow bed. This water can be reverse osmosis or otherwise multi-filtered and the resulting clean water channeled into the clear water tank, to aquaculture tanks, and/or to animals as their drinking water. If aquaculture tanks are employed the waste water from the tanks is mixed with the gray water from the hab and channeled into the grow beds, as above. If such an aquaculture loop is employed the grow beds need to be sized to accommodate the extra waste water.
If stored in insulated tanks, warm water can be recirculated throughout the CELSS to regulate internal CELSS temperature in the hab and growing area. Circulation loops in the hab walls can be used to warm the hab during limited solar exposure (i.e. night or winter). During high average exposure periods (summer), warm water can circulated through external radiators at night to dissipate heat outside the CELSS.
Even better, solar heat can be used to increase potential energy by using a solar pump to move water to a higher elevation during sunlit periods and recapturing the potential energy as it is needed for power generation or consumption. While a photovoltaic-electric pump would also work to move water, a solar Stirling pump contains fewer moving parts (only 2 check valves), has a longer expected life, and is easier to maintain. The Stirling pump would however take up a greater volume.
WATER SUBSYSTEMS:
I. RO (reverse osmosis) FILTER
A. Input: filtered white water from bio-bed
B. Outputs:
1. clear water to CWT
2. brine to bio-bed sub-surface
II. BIO-BED/greenhouse
A. Sub-surface Inputs
1. distilled evaporate from composter/drier
2. urine from HUM washroom
3. brine from RO filter
4. fan forced heated air from composter/drier
5. gray water from HUM sinks and shower
6. recycled bio-bed surface air (O2, CO2, ethylene, trace gasses)
B. Surface Input: powdered dried organics from composter/drier
C. Sub-surface Outputs:
1. white water through RO filter to CWT
2. cool air to dehumidifier condenser coils
D. Surface Outputs:
1. plant transpiration to dehumidifier
2. moisture evaporate to dehumidifier
3. O2 rich air to HUM
4. moist heated air to air well
5. medicinal herbs & food/vegetables
III. CLEAR WATER TANK - CWT
A. Inputs:
1. RO filtered H20 from bio-bed sub-surface
2. distilled H2O from dehumidifier
3. distilled H2O from air well
B. Output: clear H2O via pressure pump through UV sterilizer to HUM
Interfaces: Air, Biomass, Food, Thermal, Waste, Crew, Cooling, EVA Support, Human Accommodations, ISRU, Integrated Control, Power, Radiation Protection
Water in the water cycle comes mainly from four sources:
1. Both plants and animals transpire water vapor into the air.
2. Animals produce urine (waste water).
3. Humans use water for washing, which produces gray water.
4. Water storage bodies will evaporate water from air water interfaces
Typical water usage breaks down as follows:
human cooking/consumption: 75 l/day
bathing:400 l/day
garden: 25 l/day
Transpiration is largely a factor of temperature and lighting. In mid latitudes on Earth, most plants are only able to use 1/4 to 1/2 of the summer insolation that impacts their leaves. Above this level actually slows growth and results in heat, which the plant must shed by evaporating water.
Water Purification
Water Storage
Cistern size
Sand will store water about 50% of its bulk and water in between the sand grains is is less likely to evaporate than in an open air pond. Water can also be used for (energy storage)).
Gray water and urine are mixed and channeled into grow beds via bottom-laying perforated pipe, where various micro-organisms, fungi, and higher plants break down and convert soap oils and waste fats, food particles, dead skin, and urine into an organic food supply and oxygen. The more waste is treated by the root systems of the plants, the larger the plants grow. Fresh water is produced via plant transpiration and soil bed evaporation and is condensed out of the air by a ground loop (air well) dehumidifier and the water collected goes into the clear water tank to be UV or O3 sterilized for potable use. As the microbes, fungi, and plant roots are proven to be very efficient in filtering the organics and nutrients out of water, any water which makes it from the gray water entrance point (high point of the bed) can be stored in the white water tank located at the lowest end of the grow bed. This water can be reverse osmosis or otherwise multi-filtered and the resulting clean water channeled into the clear water tank, to aquaculture tanks, and/or to animals as their drinking water. If aquaculture tanks are employed the waste water from the tanks is mixed with the gray water from the hab and channeled into the grow beds, as above. If such an aquaculture loop is employed the grow beds need to be sized to accommodate the extra waste water.
Using water to store energy
Water has a specific heat capacity of 1 J/g K meaning a gram of water will absorb 1 Joule of energy for ever degree of temperature increase (measured in Kelvin or Celsius units).If stored in insulated tanks, warm water can be recirculated throughout the CELSS to regulate internal CELSS temperature in the hab and growing area. Circulation loops in the hab walls can be used to warm the hab during limited solar exposure (i.e. night or winter). During high average exposure periods (summer), warm water can circulated through external radiators at night to dissipate heat outside the CELSS.
Even better, solar heat can be used to increase potential energy by using a solar pump to move water to a higher elevation during sunlit periods and recapturing the potential energy as it is needed for power generation or consumption. While a photovoltaic-electric pump would also work to move water, a solar Stirling pump contains fewer moving parts (only 2 check valves), has a longer expected life, and is easier to maintain. The Stirling pump would however take up a greater volume.
Flow Rate
If the average power requirements are taken to be less than 500W, then for a 10m high (~3 stories) storage tank, a flow rate of 5.1 litres per second would be needed, assuming 100% efficiency in converting the energy into usable power (either mechanical or electrical). Microturbine have a typical efficiency ofRequired Storage Capacity
The storage capacity requirements of the tank depend on the latitude and season of course, but probably a good buffer to shoot for is at least one cloudy day (24hrs) worth of power (24x60x60x5.1), or about 441,000 liters, equivalent to a tank 2m deep and 12m diamter.WATER SUBSYSTEMS:
I. RO (reverse osmosis) FILTER
A. Input: filtered white water from bio-bed
B. Outputs:
1. clear water to CWT
2. brine to bio-bed sub-surface
II. BIO-BED/greenhouse
A. Sub-surface Inputs
1. distilled evaporate from composter/drier
2. urine from HUM washroom
3. brine from RO filter
4. fan forced heated air from composter/drier
5. gray water from HUM sinks and shower
6. recycled bio-bed surface air (O2, CO2, ethylene, trace gasses)
B. Surface Input: powdered dried organics from composter/drier
C. Sub-surface Outputs:
1. white water through RO filter to CWT
2. cool air to dehumidifier condenser coils
D. Surface Outputs:
1. plant transpiration to dehumidifier
2. moisture evaporate to dehumidifier
3. O2 rich air to HUM
4. moist heated air to air well
5. medicinal herbs & food/vegetables
III. CLEAR WATER TANK - CWT
A. Inputs:
1. RO filtered H20 from bio-bed sub-surface
2. distilled H2O from dehumidifier
3. distilled H2O from air well
B. Output: clear H2O via pressure pump through UV sterilizer to HUM