aol.com)Filtering
Water Sources for Use
in Hydrating Intravenous Fluids (IV) Onboard Space Shuttle
and International Space Station (ISS).
Author:
Jedadiah Drew Pounds State University of West Georgia (Drew0097aol.com)
Principal Investigators: Kathy DiBiasi, Carmen Ramos-Cortez, Randall Sumner The Bionetics Corporation
NASA Space Life Sciences Training Program, Kennedy Space Center, FL, Florida Agricultural and Mechanical University, Tallahassee, FL
In the space environment, there exists the likelihood of medical emergencies requiring the use of Intravenous (IV) Fluids. Aboard the Space Shuttle and ISS, dehydration caused by space motion sickness, burns, infection, and trauma are medical contingencies facing astronauts. However, due to the high cost associated with launching heavy payloads, the orbiter carries only two liters (or bags) of IV and the ISS will carry only six liters. A possible cost effective improvement to this situation includes sending an increased number of anhydrous IV bags along with a lightweight water filtration system for on board hydration and use. The NASA Space Life Sciences Training Program's (SLSTP) Flight Emphasis Group project FLUID (Filtering Liquids for Use in Intravenous Devices), explored the feasibility of producing pharmaceutical grade water by filtering various onboard water sources with a Reverse Osmosis (RO) system. The effects of the RO system on the water samples were determined for microbial content, pH, chloride content, chemical composition, conductivity, and endotoxin levels. Bacteria, endotoxin, chloride content, and pH levels were brought to within USP standards using the system. Conductivity did not fall within USP standards due possibly to restrained pump pressure. Findings support the idea that with a few additional improvements and further trials a similar RO system could be flown aboard the orbiter and ISS for use in future emergency medical situations
An average male weighs approximately 70 kg and is comprised of approximately 42 L of water. Intracellular water comprises two-thirds of this volume while one-third is found in the extracellular water. Of these 14 L of the extracellular water, which comprises the plasma, five L are circulating when the body is healthy and optimally functioning, and two to three L are required daily to maintain this level (5). The body regulates this fluid level by taking in fluids through food and drinks and excreting urine when water levels get too high. Situations can occur when the volume of circulating fluid drops below five L, and the body is unable to self-regulate. These situations, including traumas and burn-related accidents, can lead to a decreased blood volume and pressure and an increased heart rate that can ultimately lead to a lack of oxygen reaching the brain and other vital organs of the body. These situations can usually be treated by having the affected person drink oral fluids. This is not only more comfortable for the individual but also safer because the fluids are allowed to circulate through the gastrointestinal tract and thus be introduced into the body through the digestive system (5). In cases of uncontrolled vomiting, severe diarrhea, or when a victim is experiencing rapid fluid loss, such as in a severe trauma situation or burn injury, oral fluids are not a practical solution. In such cases, IV fluids are injected into the person.
Space is an environment where the potential for trauma situations or burn injuries is very high. In addition, space causes many physiological complications directly or indirectly that can cause dehydration. Within these complications, fluid shifts are of the most impacting. Fluid shifts occur in microgravity because the fluids in the body are no longer being pulled down on by gravity. Mechanisms in the body, however, that normally have to work to keep the blood and fluid volume in the upper portions of the body continue to work. This results in the fluid in the body being "shifted" up and causing puffiness in the face and symptoms of a head cold. These "shifts" cause an increase in heart stroke volume, electrolyte excretion, perspiration, and in the need to urinate frequently. They also cause a decrease in water reabsorption and thirst. The astronauts typically experience overexertion and a loss of appetite, resulting probably from their 14-20 hour workdays. This loss of appetite compromises the nutritional value of an astronaut’s diet in space and probably contributes to the immune system of the astronauts not functioning optimally (7). Another factor of the immune system problem is thought to be linked to the fact that bacteria can grow ten times faster in space, than on Earth (9). All things considered, the possibility for serious illness or injury resulting in the need for IV fluids is a constant threat to astronauts.
The Shuttle Orbiter Medical System (SOMS) which is the medical kit on board the orbiter currently carries only two L of IV fluids for a crew of five to seven people for an entire mission (6.) The International Space Station (ISS) and its crew of three will only carry six L. Two liters are not enough to provide for all of the possible medical contingencies that could occur in space. This small amount is not a result of oversight on the part of NASA doctors, but of weight restrictions due to economics. At a cost of $22,000 per kg of payload, the 2 L of IV fluids on board shuttle cost $44,000 to carry into orbit (5). A solution to this problem would be to use anhydrous IV bags and send them up containing only the powdered or frozen salts, sugars, and antibiotics necessary. Then when needed, using an ultra pure water source on board, the crew can hydrate the bags in the event of an emergency. For this to be possible, a lightweight water filtration system must be flown to purify a given water source that can meet U S Pharmacopoeia* Water for Injection (WFI) standards (11). The 1999 SLSTP project FLUID’s (Filtering Liquids for Use in Intravenous Devices) purpose was to assess the feasibility of using a similar system in the space program.
FLUID selected a Reverse Osmosis (RO) filtration system and chose to test various potential onboard water sources for bacteria, chlorine, conductivity, pH, and endotoxins. The RO system was developed in 1962 when the US Navy funded the first RO plant for the purification of seawater. Thirty years later, the US Army used the RO system in Desert Storm to again purify salt waters, and the government has since used the system to purify floodwaters. Today there are over 3000 large RO treatment plants in the United States (5).
The system works by pulling water first through a ten micron chlorine filter, (KX Industries +CTO/2 Class 1 Chlorine filter), then into an electric water pump, through the RO membrane (Ultratech of America), through a 0.5 micron filter, (KX Industries) and finally through another 0.5 micron polishing filter (KX Industries). The RO membrane works by applying external pressure of 120 psi (pounds per square inch) to a contaminated water source forcing water molecules through a semi-permeable membrane while trapping any other contaminating molecules. Therefore, instead of equilibrium being reached, as is the case through regular osmosis, contaminants are separated from their water source and pure water is produced.
The water samples were tested before and after filtration and monitored for sterility, pH ranges conductivity levels, and chloride content.
Bacterial Testing. Bacteria in an injectable water source can be extremely dangerous. The US pharmacopoeia standards require no more than ten cfu/100 ml (Colony Forming Units) of water if a source is to be deemed Water for Injection WFI (11). Bacteria can naturally enter the body through the mouth, nose, or open wounds. In space the situation is more complicated, because bacteria can grow up to ten times faster in microgravity. Infection may be caused by the bacteria itself or by poisonous waste products, called toxins (1). The body, fortunately, has defense systems against both, but direct injection of disease causing bacteria into the body would almost certainly cause a potentially lethal systemic infection (1). The heterotrophic plate count (HPC) is a procedure for estimating the number of live heterotrophic bacteria in water. HPC provides a medium in which bacteria can grow using various energy sources and detects colonies, which may arise from pairs, chains, clusters, or single-cells. The final count also depends on interaction among the developing colonies.
pH. pH of the water sources was monitored to insure the sample water being produced was neither acidic nor basic. US Pharmacopoeia standards require that the water pH be between 4.5 and 7.0 (11).
Chloride Content. The chlorine content of the various water samples was monitored to insure the removal of chlorine from the water sources by the filters. Chlorines are not only toxic to the body in concentrated levels, but can also adversely effect the taste of the water. Chlorine also destroys the RO membrane, so it imperative that chloride be removed when passing through the system.
Conductivity levels. A pure water source will register a conductivity of 0. The term conductance refers to the ability of a solution or material to carry an electric current. A liquid that conducts electricity is referred to as an electrolytic conductor. The flow of current through electrolytic conductors is accomplished by the movement of electric charges, positive and negative ions, when the fluid is under the influence of an electrical field.
Lymulus Amebocyte Lysate (LAL). (12)
Chemical Analysis. (12)
Water Collection. The RO system is based on the performance of several filters
in conjunction with a semi-permeable membrane based R O filter. Tests were run
on the water samples before and after filtrating the two samples. The water
was collected and stored in containers that could be closed such as a carboy
for the tap water and a five L water bottle for the grey water. Before collecting
the water samples, the carboy (collection device) was surveyed for holes and
was cleaned out using a triple rinse with deionized water. Then the carboy was
filled with tap water, capped, and then returned to the lab to begin testing.
The grey water was obtained from shower water using Ecolab soap and eight L
of water. Then hands and feet were washed using Igepon soap, which is the soap
slated for use on board the ISS, until 32 L of greywater had been collected.
All greywater was filtered but only two L were collected for testing. The water
samples were tested before and after filtration and monitored for sterility,
pH ranges conductivity levels, and chloride content.
System Set-up and Filtration. The system works by pulling water first through a 10 micron chlorine filter, (KX Industries +CTO/2 Class 1 Chlorine filter), then into an electric water pump, through the RO membrane (Ultratech of America), through a 0.5 micron filter, (KX Industries) and finally through another 0.5 micron polishing filter (KX Industries). A carboy containing the tap water sample was first selected and placed next to the intake hose of the system. Then sterilized 500 ml sterile pyrogen free containers were placed near the exit hose. After that, the pressure safety valve was attached and a hose was placed leading from the valve to a run-off sink. The valves in the system were all opened and the intake hose was placed into the carboy and the pump was plugged in. The system was flushed with tap water for 15 minutes purging all of the air from the tubing while the pressure was adjusted to 120 psi. The machine was unplugged and the existing filter from the X membrane housing was removed. The 10.0 micron chlorine cartridge was installed into the W housing, the RO membrane into the RO housing, the 0.5 micron filter into the X housing and finally the 0.5-high performance ceramic cartridge into the Y housing. The valves were open and flushed this time for 5- 10 minutes removing all air from the system. After future uses the system would be flushed with deionized water to avoid the build up of an organic residual film called biofilm.) If the system is not properly set-up, damage to one or all of the components could occur. As a component of quality control, all tubing, valves, and filter housings were checked to insure proper connection. The only materials needed were the pre-assembled RO system including metal frame, plastic filter housings, tubing and the three respective additional filters (pre-filter, carbon filter, polishing filter.) The filters ranged in size from 10 microns to 0.5 microns and were designed to remove carbon, particulates, chemicals, and trace elements. The 10.0 micron filter was used first to filter for chlorine. The RO filter was the next step for the filtering process, then a 0.5 micron filter, and finally a 0.5 micron polishing filter was used.
Bacterial Testing. Agar plates were prepared using a Benchtop Agarmatic Sterilizer. Ninety-five 100 X 15 cm2 plastic petri dishes were filled with R2A low nutrient agar growth medium which had been sterilized at 121° C for 15 minutes. Four plates were then tested for sterility and ability to support growth by incubating two plates for sterility and inoculating one plate with Eschericia coli and another plate with Pseudomonas aeruginosus. All four plates were incubated for 72 hours at ambient temperature. The pre-filtration method used was called the Spread Plate method. The spread plate method works well when a source with high levels of contamination are being tested. Colonies were also on the agar surface where they could be distinguished readily from particles and bubbles, transferred quickly, and compared easily to publish descriptions. This method was limited by the smaller volume of sample that could be absorbed by the agar (0.1 — 0.5 ml.). This small volume was sufficient however, due to this being a pre-filtration test. Using a vortex, each sample was thoroughly mixed. Set dilutions were then made using straight, 1:10, 1:100, and 1:1000 dilutions for tap and grey water. The samples were distributed over the surface of the culture medium by rotating petri dishes on a turntable and spreading the water samples with a disposable plastic spreader. The dishes were left to dry completely before being incubated at 35° C for 48 hours (3). All colonies were counted using an automated laser colony counter (Spiral Systems Instruments, INC, Model 500 A), immediately after incubation.
For post-filtration testing the Membrane Filter Method was used. This method permitted testing of large volumes of low-turbidity water and was the method of choice for low count waters (< 1 to 10 CFU/ml.) Culture plates were prepared by dispensing 5-ml portions of sterile HPC medium into 50- x 9-mm petri dishes and letting the medium be absorbed by the culture pad. The filtered sample was then poured through a sterile 47-mm (0.45-um,) gridded membrane filter, under partial vacuum, and rinsed with three 20-30 ml portions of sterile dilution water. Then the filter was placed in the petri dish on the pad and incubated at 35.0° (+/- 0.5° C) for 48 hours. The colonies were counted again promptly after incubation (3).
pH Range Testing. US Pharmacopoeia standards required that the water’s pH be between 4.5 and 7.0(11.) The materials used included a pH meter (Orion Model 250 A portable pH/ISE meter) two buffers (4.0 & 7.0), and three plastic 250 ml flasks. The meter was calibrated using a 4.01 and 7.00 buffer solution. Tests were then conducted on the water samples as they were being collected and later as they were leaving the exit hose of the filtration system.
Conductivity Level Tests. US Pharmacopoeia standards call for the conductivity to be 1.3 m mho/cm at 25° and 1.1 m S/cm at 20° (11.) The conductivity was monitored using hand-held conductivity monitoring unit (Orion model 126) and was performed on each carboy of sample water before filtration and after filtration as the water exited the system.
Chloride Content Tests. Chloride in the form of hypochlorous acid or hypochlorine ion (free chlorine or free available chlorine) in sample immediately reacts with DPD (N, N-diethyl-p-phenylenediamine) indicator. This reaction forms a red color proportional to the chlorine concentration. An automated colorimeter (Hach DR/700 DPD Colorimeter) and DPD free chlorine powder pillow "blanking" solution were used in this experiment along with 10 ml beakers and each of the water samples. The meter was first blanked using a blanking solution by placing the solution in a beaker and the beaker into the cell holder. Then a 10 ml sample of each water source was mixed with the DPD chlorine free powder pillow and placed into the cell holder to be read, before and after filtration (3.)
RESULTS
Bacterial Colony Counts. The bacterial colony counts resulted in the following findings. Tap water, when cultured and counted and scanned with the automated colony counter, registered 421 cfu/ml. The grey water on the other hand registered 3.22 x 106 cfu/ml. After both water samples were filtered there was insufficient growth to be analyzed using the automated counter. Upon counting by hand, the tap water revealed 1.0 cfu/ 100 ml and the grey water contained only 2.75 cfu/100 ml
Chloride Content. The chloride content of the tap water before filtration was 0.13 mg/L and the greywater contained 0 mg/L prior to filtration. After filtration, only 0.03 mg/L remained in the tap water, and the greywater continued to read 0 mg/L.
pH. The pH of the tap water before filtration was a basic 8.77. The greywater, however, was an acidic 5.9 prior to filtration. Upon completion of the filtration system, both samples registered an almost neutral 7.2. The pH of the human body is 7.0.
Conductivity. The conductivity of tap water prior to filtration was 581 ppm. Greywater also registered a very conductive 232 ppm. Upon being purified with the filtration system, the tap water had seen the most dramatic improvements, registering only a 69.6 m mhos/cm reading. Greywater, however, though registering only a 49m mhos/cm, improved less than tap water. Nevertheless, the USP standard for Chloride content is 1.3 mg/l. Therefore, the chloride content of our water is not USP quality WFI water.
Lymulus Amebocyte Lystae(LAL).
Chemical Analysis.
It is feasible, after careful evaluation of the data collected during FLUID, to fly a system similar to the RO Water Filtration System on board the space shuttle or ISS. The two sources of water collected were representative of the water that is flown aboard the shuttle and was contaminated with substances that are slated to be on ISS, such as Igepon soap. After filtration was complete, only the conductivity test failed to meet US Pharmacopoeia standards. A possible explanation for this failure rests in the fact that while greywater was to be filtered at 220 psi, due to hardware restraints, FLUID was only able to filter the samples at 120 psi.
If this project were not subjected to time restraints and funding, further trials and additional hardware could produce a cost and space efficient, tested and proven RO system that would completely filter water to meet all US Pharmacopoeia standards. Additional hardware should include all titanium filter housings, five inch filters, a ten inch RO membrane, and a manual pump. These additions would allow the entire system to fit in an area the size of a shoebox. A system of this type is currently under design by Prostar of British Columbia, Canada, who provided the RO system used for this experiment. and would cost approximately $5,000. However, this expense would pay for itself in improving the medical care of astronauts and in a permanent status on board ISS or in one quarter of a mid-deck locker on the space shuttle.
During FLUID, many valuable lessons were learned that will apply to FLUID team members’ future endeavors. Although the students were both Biology majors, other skills were attained during the research project.
Through background research and lab experience, an understanding of basic hydroponics was attained. Basic engineering principles were learned through hardware breakdown and during the repair of two RO membrane housings and the reconfiguration and un-reconfiguration of the filtration system, resorting to the use of tools such as grinders and hose clamps. A detailed understanding of the teamwork associated with work in a microbiology lab and on an extended research project was also learned.
Future applications would include using the system as a tool to aid in disaster, especially flood relief. Other uses include third world countries, lunar missions and missions to Mars.
This research was conducted along with my colleague and friend Argentria Twyman of Talladega College in Talladega, Alabama. Research was conducted at NASA’s Kennedy Space Center under the supervision of Carmen Cortes-Ramos, Randall Sumner, Cathy DiBiase, and Patricia Currier, all of The Bionetics Corporation, and Dr. Al Schlunt of Faulkner University as part of the 1999 NASA Space Life Sciences Training Program.
Special thanks to Dr. Kevin Fong* of the University College of London for beginning the project and offering his services and advice throughout the duration of testing and experimentation.