Medical drug formulation and reverse osmosis purification device

Medical drug formulation and delivery system includes a reverse osmosis device for purifying water from a source comprising a housing having an inlet for passage of water from the source, a first outlet for passage of purified water from the housing and a second outlet for passage of waste water remaining after purification. A first reverse osmosis multilayer assembly is disposed within the housing in fluid communication with the inlet for purification of at least a first portion of the water from the source. Water treatment chemicals can be positioned in a core about which the first reserve osmosis multilayer assembly is wound. The treatment chemicals are in fluid communication with the first reverse osmosis multilayer assembly to receive the first purified portion of water and for removal of at least chemical contaminants therefrom. A second reverse osmosis multilayer assembly is also wound on the core and is in fluid communication with the water treatment chemicals to receive the chemically purified water for purification of at least a second portion thereof. The second reserve osmosis multilayer assembly is in fluid communication with the first outlet so as to permit passage of the second portion of purified water therethrough. In one preferred embodiment, the first and second reverse osmosis assemblies are formed integrally in a side by side configuration. In an alternative embodiment, they are rolled about the core in an interleaf configuration.

The present invention relates to a device for purifying fluids and in 
particular to a reverse osmosis device for use, for example, in 
sterilizing and purifying fluids serially through at least two reverse 
osmosis stages, for use in a system for medical drug formulation and 
delivery and for other medical end uses. 
BACKGROUND OF THE INVENTION 
The purification or separation of fluids using synthetic membranes can be 
advantageously used in many industrial, medical and home applications. 
Typical membrane separation processes include gas and vapor diffusion, 
dialysis, ultrafiltration and reverse osmosis. 
Synthetic polymeric membranes can be applied to gaseous systems to separate 
gaseous solutions into their components. The membrane used in the gaseous 
systems must be permeable and selective, possess chemical and physical 
stability and be free of structural irregularities such as pinholes. The 
containing vessel should be capable of supporting these membranes under 
large pressure differentials; have a large membrane surface area per unit 
volume; cause a minimum pressure drop in the gas streams; and be 
inexpensive, i.e., be constructed of low-cost materials which are easy to 
fabricate and assemble. An example of such gas separation using synthetic 
membranes is the recovery of helium from natural gas and of oxygen from 
air. Such membrane separation processes, however, are often not 
competitive to known cryogenic processes because of the high power 
requirements for membrane separation. 
Synthetic polymeric membranes have been applied to dialysis wherein some 
solutes selectively permeate through the membrane based on the 
concentration gradient across the membrane. While the dialysis process is 
not particularly rapid, it has been industrially utilized, for example, in 
the recovery of caustic from rayon and the recovery of spent acid from 
metallurgical liquors. 
Ultrafiltration typically involves the separation of large solute particles 
from the solvent of the solution by forcing the solvent to pass through a 
membrane while the particles are retained to a greater or lesser extent. 
Often the separation involves a physical sieving of the particles which 
are retained on top of the membrane filter. For membranes of low pore 
radius, however, the process of ultrafiltration begins to overlap the 
process of reverse osmosis wherein the physical sieving phenomena is 
increasingly replaced with the adsorption and solubility of the solute 
within the membrane. The retained solutes consequently can have 
significant osmotic pressures which must be overcome by higher fluid 
pressures. 
Hemodialysis is an example of a dialysis process which is assisted by 
ultrafiltration. A hemodialyzer is a membrane-containing device which is 
able to remove certain waste products such as urea, creatinine and uric 
acid from the blood. The patient's blood is introduced into the 
hemodialyzer preferably under the patient's own perfusion pressure and 
flows past the membrane which is typically cellulose. The blood solutes 
containing the waste then permeate through the membrane and into the 
dialysate, a sterilized solution formulated to control solute permeability 
through the membrane. Because osmosis may result in the undesirable net 
transfer of water from the dialysate into the blood which may result in 
edema, hemodialysis is often utilized in conjunction with ultrafiltration 
to remove the excess water. The dialysate can be prepared by the 
combination of purified water, produced by reverse osmosis, and the 
desired concentrate. 
Reverse osmosis using synthetic polymeric membranes has been used for a 
variety of industrial end products. Such processes include the 
desalination of sea water and the processing of food and beverages. The 
alternative method of processing is by distillation. However, because of 
the high energy requirements of distillation, reverse osmosis processes 
compare favorably as the most economic route. Furthermore, for solutions 
susceptible to degradation at high temperatures such as fruit juices, 
reverse osmosis may be the most practical manner of processing the 
solutions while preventing substantial loss of desirable components in the 
original solutions. 
An important use of the reverse osmosis process in the medical field is its 
application to peritoneal dialysis therapy. A generalized discussion of 
peritoneal dialysis therapy is discussed and described in U.S. Pat. No. 
4,239,041 to Popovich et al. In particular, the Popovich patent discusses 
a fluid infusion method for continuous, ambulatory peritoneal dialysis 
(CAPD). The CAPD process differs from the more popular hemodialysis 
process in that it utilizes the body's natural peritoneal membrane in 
order to provide for the function of the artificial kidney. The CAPD 
process, however, while being ambulatory, is performed during the 
patient's normal, daily routine and requires treatment several times 
during the day. For this reason, the patient must remain by the dialysate 
supply during the entire period of treatment. This obviously will conflict 
with the patient's daytime activities and/or job requirements. 
Alternatively, peritoneal dialysis can be performed at a hospital or clinic 
which requires that the patient visit the facility in order to obtain the 
required treatment. Such a visit requirement also has its inherent 
limitations on the normal activities of the patient. 
Peritoneal dialysis is also generally discussed and described in the 
"Handbook 6010, Automated Peritoneal Dialysis", 1979 which is incorporated 
herein by reference. This handbook was distributed by B-D Drake Willock, a 
division of Becton, Dickenson and Co. in New Jersey and discusses that 
dialysate which is prepared from purified water can be infused into the 
patient's peritoneum through a catheter. Dialysis of the patient's blood 
through the peritoneal membrane and into the purified water region then 
occurs, allowing the body to excrete water, metabolites and toxins, and to 
regulate fluid, electrolyte and acid-base balance. The waste dialysate is 
subsequently drained out of the body. Peritoneal dialysis can be performed 
by various methods such as continuous and intermittent, as explained in 
Miller et al. "Automated Peritoneal Dialysis Analysis of Several Methods 
of Peritoneal Dialysis", Vol. XII Trans. Amer. Soc. Artif. Int. Organs p. 
98 (1966). 
Problems related to peritoneal dialysis include the difficulty in 
maintaining sterile conditions so as to prevent infection and the 
complexity of operating currently available peritoneal dialysis systems. A 
peritoneal dialysis device manufactured by Physio-Control Corporation of 
Redmond, Washington is generally described in "PDS 400 Service Manual P/N 
10454-01 July, 1981" which is also incorporated herein by reference. The 
device purifies the source water using a reverse osmosis module which is 
formed of a plastic housing containing a spiral wound membrane of 
cellulose triacetate. The device mixes the purified water with concentrate 
to form a dialysate, and then delivers the dialysate to the patient. The 
system controls the dialysate delivery at a set inflow rate and period and 
a set outflow period. An alarm is sounded and the system is turned off if 
various parameters are not within the set ranges. The parameters include 
the dialysate temperature, the dialysate conductivity, the inflow and 
outflow volume, and the system overpressure. The Physio-Control device is 
made up of two subsystems; the RO unit and the proportioning and 
monitoring unit. The device is bulky and complex in operation and requires 
extensive training of either the medical personnel or the patient that 
operate it. Additionally, extensive preventive maintenance is required to 
keep the system operational. Such maintenance includes the replacement of 
the RO prefilter, filters and O-rings within the device every 500 hours of 
use as well as the cleaning of the RO sump pump. In addition, the device 
requires cleansing with bleach every 100 hours. Moreover, an extensive 
disinfection with formaldehyde must be performed before patient use if the 
sterile path has been broken during the functional test, calibration or 
adjustment of the device. 
Another peritoneal dialysis device was designed by Ramot Purotech Ltd. The 
device employs RO membrane filtration through an RO cell formed of a large 
number of small membranes supported on plastic plates. After mixing the 
filtered water with concentrate to form the dialysate, the dialysate is 
fed by gravity to the patient. The outflow from the patient is also done 
by gravity into a waste bag. The need to connect the dialysate to the 
patient, leads to difficulties in maintaining sterile conditions. 
Yet another peritoneal dialysis system is disclosed in U.S. Pat. No. 
4,586,920; 4,718,890; and 4,747,822 to Peabody. The patents recite a 
continuous flow peritoneal dialysis system and process in which a 
continuous flow of sterile dialysis fluid is produced and caused to flow 
through the peritoneal cavity of the patient in a single-pass open 
circuit. A gravity fed system is utilized to flow the fluid into the 
patient's peritoneum. The pressure of the peritoneum and the volume of 
fluid into the peritoneum are monitored to ensure efficient and 
comfortable peritoneal dialysis. The pressure monitors of the system are 
capable of controlling the flow of fluid into the peritoneum. This system, 
however similar to others previously discussed, does not address the 
manner in which sterile conditions may be maintained nor the daunting 
complexity of operation required to be performed by the patient or care 
giver to use and maintain the system. 
These and other problems have been solved in part by another device for 
peritoneal dialysis treatment called the Inpersol Cycler.TM. 1000, the 
Handbook of which is incorporated herein by reference. The Cycler.TM. is 
used to perform peritoneal dialysis in continuous cycling peritoneal 
dialysis (CCPD) and intermittent peritoneal dialysis (IPD) applications. 
The Cycler.TM. 3000 is used to not only perform CCPD and IPD but also 
tidal peritoneal dialysis (TPD). The Cycler.TM. is portable and is 
designed to be used in the home as well as in the clinic or hospital. In 
typical CCPD applications the exchanges are made at night while the 
patient is sleeping. A portion of the final dose is retained in the 
peritoneum during the day and drained out at the beginning of the nightly 
exchanges. The cycler system includes the cycler control unit and the 
stand. The stand holds the cycler unit, and fresh and spent dialysis 
fluids. The cycler control unit contains the warmer, weighing system, 
valving system and control electronics. 
Notwithstanding the Cycler.TM., the problems of other known peritoneal 
dialysis devices have been solved by the present invention which is 
directed to a reverse osmosis (RO) filtration device for purifying water 
and for use in a user friendly automatic home dialysis system which will 
permit the patient to obtain peritoneal dialysis during sleeping hours. In 
this fashion, the patient will be free to conduct his normal activities 
during his waking or business hours without the interference of dialysis 
treatment. Additionally, the RO device and system of the present invention 
provide a self-contained, compact and sophisticated system whereby 
peritoneal dialysis is automatically performed and continuously controlled 
so as to allow the patient to undergo peritoneal dialysis at home with 
minimal need for patient intervention. This permits the patient to lead a 
more natural and fuller life than permitted under known treatment 
procedures. 
The RO device and system of the present invention also provide for a low 
cost, efficient means to produce solutions of sufficient sterility, low 
pyrogen content and low dissolved mineral content for many other 
industrial and medical applications. Because of the compactness of the 
apparatus and its ease of use, purified fluids such as sterile and 
pyrogen-free water can be produced on site as needed without the 
inconvenience and cost of storing large quantities of the purified fluid. 
When applied to purifying water, the invention produces water of 
sufficient sterility such that the purified water can be employed in 
peritoneal dialysis, irrigation of patients during surgery or 
postoperative therapy, and pharmaceutical production for oral and 
intravenous administration. Additionally, the RO device can produce 
sterile water for the formulation of dialysate solution required in 
hemodialysis treatment. The purified water as produced by the device and 
system of the present invention can satisfy U.S.P. requirements as 
presented in the United States Pharmacopeia, The National Formulary 
P1456-1574, 1596-1598, 1705-1710, Jan. 1, 1990, USP XXII United States 
Pharmacopeial Convention, Inc. Also, the RO device and system avoids any 
need for terminal sterilization as required by known peritoneal dialysis 
devices. 
Alternatively, the RO device and system of the present invention may be 
adapted to supply sterile water for the formulation of dialysate for use 
in hemodialyzers. The hemodialyzers in turn use the dialysate to purify 
the patient's blood in a manner currently used in hospitals and clinics. 
For less demanding processes where sterility is not a major concern, the RO 
device and/or system of the present invention may be adapted to dialysis 
and ultrafiltration processes. Typical end use applications include those 
previously discussed such as the recovery of spent caustic or acid 
solutions from industrial production liquors (i.e. rayon steep liquor and 
metallurgical liquor). 
The present invention is also directed toward the method of manufacturing 
the RO device in a manner which would minimize the cost of manufacturing 
and expedite it as well. Assembly steps include the application of 
adhesive in an automated manner by roller coating, induction bonding, 
sonic welding, and radiation sterilization. 
SUMMARY OF THE INVENTION 
The present invention is directed to an apparatus for purifying fluid from 
a source comprising first reverse osmosis means adapted for fluid 
communication with the source for purification of at least a portion of 
the fluid from the source; and second reverse osmosis means being in fluid 
communication with the first reverse osmosis means to receive at least 
some of the purified portion of fluid for further purification of at least 
a further portion of the fluid. 
The fluid may be in the liquid or gaseous state. The configuration of the 
reverse osmosis means includes reverse osmosis multilayer assemblies which 
are either spirally wound or stacked in a parallel leaf configuration. 
Alternatively, the reverse osmosis means is in the form of hollow 
non-porous semipermeable membrane fibers composed of synthetic membrane. 
Synthetic membranes useful for reverse osmosis include cellulose nitrate, 
cellulose acetate, polyamides, polyimides, polytetrafluoroethylene, 
poly-(vinyl chloride) and polysulfone. 
Preferably the RO apparatus is for use with a potable water source and the 
first reverse osmosis means comprises a first reverse osmosis multilayer 
assembly spirally rolled about a first axis so as to provide a generally 
spiral flow path of the water from the source. The second reverse osmosis 
multilayer assembly is spirally rolled about a second axis so as to 
provide a generally spiral flow path for at least some of the purified 
first portion of water from the first reverse osmosis means. 
Preferably, the first and said second reverse osmosis multilayer assemblies 
are formed integrally and the first axis and the second axis are 
co-linear. A separator means is disposed so as to fluidly separate the 
integral multilayer assembly when rolled about its axis into the first and 
the second reverse osmosis multilayer assemblies. 
In one embodiment, the separator means is an impermeable adhesive. Also the 
integral multilayer assembly comprises first reverse osmosis membrane 
layer; porous mesh layer; second reverse osmosis membrane layer; and 
porous permeate layer. An interior container can enclose either the first 
or the second reverse osmosis multilayer assembly. 
In an alternative embodiment, the first reverse osmosis means is disposed 
in an interleaf configuration with the second reverse osmosis means and 
each comprises at least a reverse osmosis multilayer assembly spirally 
rolled about a common axis. Preferably, the first reverse osmosis 
multilayer assembly comprises first reverse osmosis membrane layer; porous 
mesh layer; second reverse osmosis membrane layer; and first porous 
permeate layer. The second reverse osmosis multilayer assembly comprises 
third reverse osmosis membrane layer; second porous permeate layer; fourth 
reverse osmosis membrane layer; and third porous permeate layer. 
The present invention is also directed to a method for purifying fluid from 
a source comprising passing fluid from the source through a first reverse 
osmosis means being in fluid communication with the source so as to purify 
at least a portion of the fluid from the source; and passing the purified 
first portion of fluid through a second reverse osmosis means being in 
fluid communication with the first reverse osmosis means to receive the 
purified portion of water for further purification of the fluid. 
Preferably, the fluid can be water. 
According to another embodiment, the present invention is directed to an 
apparatus for purifying water from a source comprising housing having an 
inlet for passage of water from a source, a first outlet for passage of 
purified water from the housing and a second outlet for passage of waste 
water remaining after purification; first reverse osmosis means disposed 
within said housing and being in fluid communication with the inlet for 
purification of at least a first portion of the water from the source; the 
first reverse osmosis means also being in fluid communication with the 
second outlet for passage of waste water through the second outlet; 
chemical purification means being in fluid communication with the first 
reverse osmosis means to receive the first purified portion of water and 
for removal of at least chemical contaminants from the first purified 
portion of water; and second reverse osmosis means being in fluid 
communication with the chemical means to receive the chemically purified 
water for purification of at least a second portion of the chemically 
purified water, the second reverse osmosis means also being in fluid 
communication with the first outlet so as to permit passage of the second 
portion of purified water through the first outlet. 
In one embodiment, the housing further comprises a third outlet for passage 
of waste water remaining after purification, and the first reverse osmosis 
means is in fluid communication with the third outlet so as to permit 
passage of waste water through the third outlet. The second reverse 
osmosis means is in fluid communication with the second outlet so as to 
permit passage of waste water through the second outlet. 
The housing is formed of a material possessing sufficient structural 
integrity to withstand the pressure requirements of the reverse osmosis 
process. The material may be but is not limited to steel, aluminum, 
fiberglass and Kevlar.TM.. Also, the housing includes an elongated hollow 
cylindrical container having a base and an open end and includes a cap 
configured and dimensioned to seal the open end in a fluid tight 
configuration. The cap has an inlet passageway for admitting water from 
the source, a first passageway for purified water and a second passageway 
for waste water. A third outlet passageway could also be provided for 
passage of waste water. A generally cylindrical core is disposed within 
the housing and extends from the base to the cap. The integral multilayer 
assembly is rolled about the outer surface of the cylindrical core so as 
to provide for spiral flow paths of the water to be purified. The 
cylindrical core has a hollow central portion and the chemical means is 
disposed within the hollow central portion. The chemical means includes 
but is not limited to diatomaceous earth, clay, ion exchange resins, 
activated carbon or other similar material and mixtures thereof. The 
chemical means provides a variety of functions including the removal of 
dissolved gases and chloramine contaminants. Filter plugs are disposed at 
the ends of the hollow central portion so as to contain the chemical means 
therebetween. The apparatus further comprises a second cylindrical hollow 
container having a base and an open end and is configured and dimensioned 
so as to be adapted to be positioned within the first container and to 
receive and to seal the second reverse osmosis means therein. At least one 
0 ring or other sealing means is disposed between the open end of the 
second cylindrical hollow container and the impermeable adhesive disposed 
along the central portion of the integral multilayer assembly so as to aid 
in sealing the first osmosis means within the second container. 
Preferably, the integral multilayer assembly comprises first reverse 
osmosis membrane layer; porous mesh layer; second reverse osmosis membrane 
layer; and porous permeate layer. Also, the first and said second reverse 
osmosis membrane layers each comprises nonporous semi-permeable membrane 
layer; porous ultrafiltration layer; and porous support layer. The 
semi-permeable membrane layer is formed generally of a solid nonporous 
continuous thin polymeric composition and the porous support layer is 
formed generally of polyamide which can be either of a woven or non-woven 
configuration. 
After being rolled about the outer surface of the cylindrical core, the 
reverse osmosis multilayer assembly generally includes in a radially 
outwardly configuration from the surface, the porous permeate layer, the 
second reverse osmosis membrane layer, the porous mesh layer and the first 
reverse osmosis membrane layer. Preferably, the nonporous semi-permeable 
membrane layers of the first and the second reverse osmosis membrane 
layers are disposed adjacent the porous mesh layer. 
In another preferred embodiment of the present invention, the apparatus has 
a second reverse osmosis means being in fluid communication with the first 
reverse osmosis means to receive the first purified portion of water for 
purification of at least a second portion of the purified water, the 
second reverse osmosis means also being in fluid communication with the 
second outlet for passage of waste water through the second outlet. 
Chemical means in fluid communication with the second reverse osmosis 
means receives the second purified portion of water and removes at least 
chemical contaminants from the second purified portion of water. The 
chemical means is also in fluid communication with the first outlet so as 
to permit passage of the second portion of purified water through the 
first outlet. 
In another embodiment, the first reverse osmosis means is disposed in an 
interleaf configuration with the second reverse osmosis means. The first 
reverse osmosis means comprises at least a first reverse osmosis 
multilayer assembly and the second reverse osmosis means comprises at 
least a second reverse osmosis multilayer assembly. Both the first and the 
second reverse osmosis multilayer assemblies are spirally rolled about a 
common axis. The first reverse osmosis multilayer assembly comprises first 
reverse osmosis membrane layer; porous mesh layer; second reverse osmosis 
membrane layer; and first porous permeate layer. Also, the second reverse 
osmosis multilayer assembly comprises third reverse osmosis membrane 
layer; second porous permeate layer; fourth reverse osmosis membrane 
layer; and third porous permeate layer. 
Preferably, the first, second, third and fourth reverse osmosis membrane 
layers each comprises nonporous semi-permeable membrane layer; porous 
ultrafiltration layer; and porous support layer. The semi-permeable 
membrane layer is formed generally of a solid nonporous continuous thin 
polymeric composition such as polyamide. The porous support layer can be 
made of polyamide. The polyamide can be of a woven or non-woven 
configuration. 
After the reverse osmosis multilayer assemblies are rolled about the outer 
surface of the cylindrical core, they include in a radially outwardly 
configuration from the surface, the third porous permeate layer, the 
fourth reverse osmosis membrane layer, the second porous permeate layer, 
the third reverse osmosis membrane layer, the first porous permeate layer, 
the second reverse osmosis membrane layer, the porous mesh layer and the 
first reverse osmosis membrane layer. 
The nonporous semi-permeable membrane layers of the first and the second 
reverse osmosis membrane layers are disposed adjacent the porous mesh 
layer. Preferably, the nonporous semi-permeable membrane layers of the 
third and the fourth reverse osmosis membrane layers are disposed adjacent 
the second porous permeate layer. 
In an alternative embodiment for purifying water from a source, the method 
comprises passing water from the source through a first reverse osmosis 
means being in fluid communication with the source so as to purify at 
least a first portion of the water from the source; passing the purified 
first portion of water through chemical means being in fluid communication 
with the first reverse osmosis means to receive the first purified portion 
of water and for removal of at least chemical contaminants from the first 
purified portion of water; and passing the chemically purified water 
through a second reverse osmosis means being in fluid communication with 
the chemical means to receive the chemically purified water for 
purification of at least a second portion of the chemically purified 
water, the second reverse osmosis means also being in fluid communication 
with the first outlet and the second outlet so as to permit passage of the 
second portion of purified water through the first outlet and for passage 
of waste water through the second outlet. 
In yet another preferred embodiment, after passing water from the source 
through a first reverse osmosis means so as to purify at least a first 
portion of the water from the source, the method comprises passing the 
purified first portion of water through a second reverse osmosis means 
being in fluid communication with the first reverse osmosis means to 
receive the purified first portion of water for further purification of at 
least a second portion of the water; and passing the purified second 
portion of water through chemical means being in fluid communication with 
the second reverse osmosis means to receive the second purified portion of 
water and for removal of at least chemical contaminants from the purified 
second portion of water, the chemical means also being in fluid 
communication with the first outlet so as to permit passage of the 
chemically purified water through the first outlet. If desired, the 
purified water can be passed through a filtration means for further 
purification. 
The housing of the reverse osmosis device includes an elongated hollow 
first cylindrical container having a base and an open end. A generally 
cylindrical core is disposed within the housing and extends from the base 
to the cap. The first and second reverse osmosis means are rolled about 
the outer surface of the cylindrical core so as to provide for spiral flow 
paths of the water to be processed. The cylindrical core has a hollow 
central portion for receiving chemical means within the hollow central 
portion. The system further comprises a second cylindrical hollow 
container having a base and an open end and which is configured and 
dimensioned so as to be adapted to be positioned within the first 
container, and to receive and to seal the first reverse osmosis means 
therein. The housing includes a cap configured and dimensioned to fluidly 
seal the open end and includes an inlet passageway for admitting water 
from the source, a first outlet passageway for purified water and a second 
outlet passageway for waste water. The cap has an inner face and an outer 
face and further comprises a plurality of protrusions extending from the 
inner face into selective contacting relationship with the core at 
predetermined positions. The protrusions are fusible with the core upon 
application of at least one of ultrasonic and thermal energy. Also, the 
second cylindrical container has an inner face and further comprises a 
plurality of protrusions extending from the inner face into selective 
contacting relationship with the core at predetermined positions. The core 
has a plurality of passageways predeterminately coupled through the inner 
face of the cap and the inner face of the second container to provide 
fluid flow paths for the water from the source, the waste water and the 
purified water into, through and out of the housing. 
The system further comprises means for restricting the flow of water 
therethrough and also thereby through the reverse osmosis device. The flow 
restricting means comprises a flow plug configured and dimensioned so as 
to be adapted to be disposed within at least one passageway in the core. 
The flow plug has a reduced effective cross sectional area than the at 
least one passageway so as to restrict the flow of water through the 
passageway and provide for predetermined pressures on either side of the 
flow plug. Preferably, at least two flow plugs are disposed in a different 
passageway in the core. 
A method of manufacturing a reverse osmosis device on a core for purifying 
water from a source comprises providing an integral reverse osmosis 
multilayer assembly having first reverse osmosis membrane layer; porous 
mesh layer; second reverse osmosis membrane layer; and porous permeate 
layer; sealing a central portion of the integral multilayer assembly; 
sealing at least one edge of the multilayer assembly to the core; sealing 
along two opposed side edges of the integral multilayer assembly; rolling 
the integral multilayer assembly in a spiral configuration on the core; 
and bonding the seals by induction heating so as to fluidly seal the 
integral multilayer assembly along the edges and the central portion and 
so as to separate the integral multilayer assembly into a first reverse 
osmosis multilayer assembly and a second reverse osmosis multilayer 
assembly. In one embodiment, sealing is obtained by disposing an 
impermeable adhesive along the length of a central portion of the integral 
multilayer assembly; and disposing an impermeable adhesive along the side 
edges of the integral multilayer assembly. 
The method further comprises enclosing the spirally rolled and bonded 
integral multilayer assembly in a housing having an inlet for passage of 
water for a source, a first outlet for passage of purified water from the 
passage of purified water from the housing and a second outlet for passage 
of waste water remaining after purification, disposing the first reverse 
osmosis multilayer assembly within the housing in fluid communication with 
the inlet for purification of at least a first portion of the water from 
the source, and disposing the second reverse osmosis multilayer assembly 
within the housing in fluid communication with the first reverse osmosis 
means to receive the first purified portion of water for purification of 
at least a second portion of the purified water, the second reverse 
osmosis means also being disposed in fluid communication with the second 
outlet for passage of waste water through the second outlet. 
Alternatively, the method can comprise providing an integral reverse 
osmosis multilayer assembly having first reverse osmosis membrane layer; 
first porous mesh layer; second reverse osmosis membrane layer; porous 
permeate layer; third reverse osmosis membrane layer; second porous 
permeate layer; fourth reverse osmosis membrane layer; and third porous 
permeate layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the description which follows, any reference to either orientation or 
direction is intended primarily for the purpose of illustration and is not 
intended in any way as a limitation of the scope of the present invention. 
The peritoneal dialysis system (PDS) 10 of FIG. 1 of the present invention 
is designed to preferably utilize potable water and prepackaged drug 
mixtures or concentrate to enable a patient to obtain peritoneal dialysis 
at home and preferably at night. If desired, other sources of water can be 
utilized as well. For instance, non-potable tap water can be used to 
produce potable water by the RO device which in turn can be utilized by 
the peritoneal dialysis system. 
As shown in FIG. 1, potable water from a source 12 is admitted optionally 
through prefilter 13 to remove particulates which are greater or equal to 
about 5 microns in size and through a valve 14 and heat exchanger 16 into 
a heater 18 and thereafter is passed through a high pressure pump 20 to 
the reverse osmosis (RO) device 22 according to the present invention. 
Within the RO device 22, some of the potable water is purified and exits 
optionally through a sterilizing filter 23 into a surge container such as 
a bag 24. The waste water is passed through an on/off clamp 26 to the heat 
exchanger 16. The heat exchanger 16 transfers at least a portion of the 
heat from the waste water so as to warm the original potable water before 
the potable water passes through heater 18. The on/off clamp 28 can 
regulate the passage of the purified permeate to the surge container 24 
and an on/off clamp 30 can alternatively allow for passage of excess 
permeate to the drain or another collection container for storage through 
the isolation one-way valve 56. 
A conductivity sensor 25 is placed downstream of the RO device 22 to 
continually or periodically monitor the electrical resistivity of the 
purified permeate water. Alternatively, the conductivity sensor may be 
placed downstream of on/off clamp 30 to periodically monitor the 
electrical resistivity of the purified permeate. 
A pump 32 passes the ultrapure water or permeate from the surge container 
24 to mixing bags 34 and 36. Concentrate such as a prepared drug or other 
desired mixture from sources 38 and 40 passes through metering pumps 42 
and 44 that pass a predetermined amount of concentrate into the mixing 
container 34 and 36 that can mix and measure and alternatively feed to the 
downstream pump 46. Also, drug sources in addition to sources 38, 40 can 
be provided, as desired, or only one may be utilized if preferred. In a 
preferred embodiment, source 38 could include a predetermined dextrose 
solution of about 65% concentrate. To allow for conductivity monitoring, 
the dextrose source 38 can be provided with a predetermined amount of 
electrolytes that can be measured upon coming into contact with 
conductivity sensor, which will be discussed in more detail below. 
Similarly, other sources can be provided with electrolyte markers that 
would allow for conductivity measurement as well. Of course, to the extent 
that other sources already contain electrolytes, any additional markers 
are not required but could aid in the measurement process. Conductivity 
sensors 75 and 77 are placed downstream of mixing bags 34 and 36 
respectively so as to continually or periodically monitor the electrical 
resistivity of the mixed solutions from the mixing bags. Alternatively a 
conductivity sensor may be placed downstream of clamp 76 and 78 so as to 
periodically monitor the electrical resistivity of the mixed solutions 
from the mixing bags. The conductivity sensors may also be used to aid in 
the formulation of the dialysate. 
Advantageously, a heater 45 is used to control the temperature of the 
dialysate within desired ranges. 
By means of the high accuracy pump 46, the dialysate is then admitted 
through a dual lumen catheter 48 into a patient's peritoneal cavity 50. 
Discharge from the patient is provided by a downstream high accuracy pump 
52 into a discharge measurement container 54 and thereafter, through pump 
55 and an isolation one-way valve 56, which serves as a barrier against 
virus, bacteria and pyrogen, to a drain 58. Alternatively, with the on/off 
clamp 84 closed and on/off clamp 86 opened, the discharge from the patient 
passes through the heat exchanger 16 to transfer at least a portion of the 
heat from the discharge so as to warm the original potable water before 
the potable water passes through heater 18. The discharge is subsequently 
drained off through isolation one-way valve 56 to drain 58. 
The surge container 24 is optionally supported by hook means 60 which is 
connected to weight measurement mechanism 64. The discharge measurement 
container 54 is supported by hook means 62 which is connected to weight 
measurement mechanism 66. In one preferred embodiment, the weight 
measurement mechanisms provide electrical signals corresponding to the 
weight of the contents of the respective container. These signals are 
transmitted to a computer control system (not shown in FIG. 1) that is 
discussed in greater detail below. 
As shown in FIG. 1, an outlet through on/off clamp 71 is provided upstream 
of the mixing containers 34 and 36 for flushing, priming and calibrating. 
Additional clamps 72 and 74 are provided to close off the downstream flow 
paths when clamp 71 is opened. In this manner, the permeate or ultrapure 
water combining with concentrate from sources 38 and 40 can initially be 
passed through isolation valve 56 to drain until proper operation and 
priming is obtained. Thereafter, clamp 71 is closed and clamps 72 and/or 
74 are opened according to the desired operation. When clamps 72 and 74 
are closed and clamp 71 is left open, the discharge measurement container 
54 along with the hook means 62 and weight measurement mechanism 66 can 
then be used to calibrate the delivery rate of the pumps 32, 42 and 44 
individually. Similarly, when clamp 47 is opened and clamp 49 is closed, 
the discharge measurement container 54 along with the hook means 62 and 
weight measurement mechanism 66 can be used to calibrate pumps 46 and 80 
individually. When both clamps 47 and 49 are closed, calibration of pump 
52 can be performed. Other on/off clamps 76 and 78 control the outflow 
from mixing containers 34 and 36. 
The on/off clamp 86 and pump 55 control the flow of the discharge from the 
discharge measurement container 54 to the heat exchange 16 and isolation 
one-way valve 56. Alternatively, with clamp 86 closed, the discharge can 
flow through pump 55 and clamp 84 to the isolation one-way valve 56 to 
drain 58. 
Within the mixing containers 34 and 36, the concentrate and permeate are 
adequately mixed to provide a dialysate solution suitable for the 
peritoneal dialysis treatment of the patient 50. The mixing can be 
performed by known methods which include, for example, ultrasonic, 
mechanical, static and also electromechanical modes of mixing. One 
preferred embodiment of mixing apparatus is of the electromechanical type 
and is described in greater detail below. 
Optionally, a container 82 and pump 80 are connected just upstream of clamp 
49 to provide a method of administering drugs into the patient 50. Such 
drugs include but are not limited to insulin, heparin, antibiotics, 
erythro poietin, and nutritional supplements like calcium, magnesium and 
amino acids. 
The dual lumen catheter 48 is of a configuration that is surgically 
implanted into the patient 50 and extends into the peritoneal cavity by 
appropriate lumen tubing (not shown) as is well known to those in the 
medical art. One lumen is coupled to the pump 46 while the other lumen is 
coupled to discharge pump 52. 
In operation, potable water such as from a tap, is passed through valve 14, 
warmed to the desired temperature by heat exchanger 16 and heater 18 and 
pumped under pressure through pump 20 into RO device 22. Some of the tap 
water is purified and sterilized so as to be free of pyrogens and to have 
an electrical resistivity of greater than approximately 0.05 megaohms per 
centimeter, which corresponds to about 25 ppm dissolved solids content, as 
determined by conductivity sensors. Waste water exits through clamp 26 and 
goes into the heat exchanger 16. The purified water or permeate is 
optionally passed through a sterilizing filter (i.e., 0.22 micrometer 
(.mu.m) filter) and then admitted into a surge container 24 where it is 
optionally measured and stored, as desired, until pumped out by pump 32 
into mixing containers 34 and/or 36. Also, concentrate of a prepared drug 
and treatment mixture, in paste, liquid or solid form is premeasured in 
source 38 and 40 and advanced by metering device such as pumps 42 and 44 
or other delivery techniques or methodologies into the flow path passing 
with the permeate into the mixing containers 34 and/or 36. After suitable 
mixing the dialysate solution in mixing containers 34 and/or 36 is pumped 
into the patient 50 by pump 46 through one lumen of the dual lumen 
catheter 48. Optionally, drugs may be administered to the patient 50 by 
pumping the drugs from container 82 into the line just upstream of the 
catheter. In a continuous mode of operation, the waste dialysate is pumped 
from the peritoneal cavity through pump 52 to the drain 58 or 
alternatively to heat exchanger 16 before being released through drain 58. 
The PDS system 10 of the present invention can also be operated for 
intermittent and tidal modes of peritoneal dialysis treatment, as desired. 
In some modes, the dual lumen catheter 40 can be replaced at points A and 
B with a single lumen catheter in accordance with known procedures as 
shown in FIG. 2. 
Where the present system is adapted to supply sterile dialysate for use 
with a hemodialyzer 300, the catheter is replaced at points A and B by 
fluid connections to a hemodialyzer 300 as shown in FIG. 3. Metering pumps 
302 and 304 are used to flow the patient's blood into and out of the 
hemodialyzer 300. Alternatively, the catheter can be replaced at points A 
and B by fluid connections to a hemoultrafilter 900 as shown in FIG. 36. 
Metering pumps 902 and 904 are used to flow the patient's blood into and 
out of the hemoultrafilter 900. A general description of hemofiltration of 
blood is presented in "Handbook of Dialysis", Little, Brown and Company, 
Boston/Toronto (1988) at pages 144-45 which are incorporated herein. In 
the course of hemofiltration treatment, about 25 to 120 liters of blood 
make up solution will be supplied from point A in FIG. 36 to be combined 
with the concentrated blood exiting from the hemoultrafilter device 900. 
Waste solution exits from the hemoultrafilter device at point B. 
The flow paths shown in FIG. 1 are provided by tubing well known to medical 
personnel. However, the tubing or flow paths downstream of the RO device 
22 and through to the catheter 48 are maintained preferably in a sterile 
condition. For this reason, connections or couplings of the tubings and 
the various components of the PDS system 10 are kept sterile as well. 
Preferably, these flow paths including the RO device are provided in a 
modular compartment, as described in greater detail below, so that the 
patient need only replace the module compartment when necessary to 
replenish the RO device or the concentrate. The RO device itself is 
sterilized by radiation. Likewise, the concentrate is sterilized by 
terminal sterilization or by a sterile filling technique as taught, for 
example, in U.S. patent application Ser. No. 07/510,317, R.J. Kruger, et 
al. filed 4/17/90 for "Method for Sterilizing and Enclosure with 
Non-Condensing Hydrogen Peroxide-Containing Gas", which is incorporated 
herein by reference. Alternatively, a sterile connecting technique 
described in FIG. 35 may be used for connecting containers 38, 40 and 82 
to the system as shown in FIG. 1. As shown in FIG. 35, a glass bottle 
container 580 having a rubber septum cap 582 is placed into a receiving 
holder 586 having a rubber septum seal 588. The receiving holder 586 holds 
the rubber septum 582 in a fluidly sealed manner and is disposed adjacent 
to the rubber septum seal 588 so as to leave a space 590. Hydrogen 
peroxide solution from about 2% to about 50% concentration is then 
introduced into the space 590 through inlet 592 to sterilize the space 
590. When the sterilization is completed the hydrogen peroxide solution 
may discharge through outlet 594. Subsequent to the sterilization the dual 
lumen needle 596 or optionally two needles is moved upward puncturing the 
rubber septum seal 588 and the rubber septum 582 so as to sterilely 
connect the glass bottle container 580 to the system. 
Sterile decoupling may be performed by retracting the dual lumen needle 596 
below the rubber septum seal 588. The rubber septum 582 can then be 
decoupled from receiving holder 586 without contaminating dual lumen 
needle 596. 
To further maintain sterile conditions, fluid is drained out of the system 
through an isolation, one-way valve 56 so as to prevent the introduction 
of virus, bacteria and pyrogen from the drain 58. 
The above combination of procedures for maintaining sterile conditions 
entering the flow paths and thereby the peritoneal cavity of patient 50. As 
a result of the system being able to maintain highly sterile conditions, a 
final 0.22 .mu.m sterilizing filter immediately upstream of the catheter 
is not required before the dialysate is delivered to the patient. 
The PDS system 10 of the present invention allows not only daytime or acute 
use but also for nighttime peritoneal dialysis treatment of patients. In 
this manner, patients can avoid the difficulties and discomfort that 
occurs with other peritoneal dialysis treatments requiring hospital or 
clinic visits. It is advantageous to utilize nighttime treatment in order 
to permit the patient to lead a more normal life during the waking hours. 
In addition, the method of treatment preferably to be employed with the 
PDS system of the present invention will require less dialysate to be 
stored within the peritoneal cavity during the dry period since there will 
be sufficient dialyzation by the continuous surge and flushing of the 
dialysate through and from the peritoneal cavity during the wet period. 
In addition, the PDS system 10 is a gentler treatment system than that 
which is obtained with the more dramatic hemodialysis. In addition, the 
psychological factors inherent in hemodialysis treatment are avoided by 
the present system. Furthermore, the PDS system 10 is a simpler and less 
complicated system than is required with hemodialysis. The PDS system 10 
thus allows a patient to avoid the dramatic environment facing such a 
patient in a hospital or clinic for either hemodialysis or conventional 
peritoneal dialysis treatments. 
Also, by allowing the peritoneal membrane to be dry for a good portion of 
the day, problems otherwise present with other treatments can be avoided 
or minimized. Furthermore, the PDS system 10 by means of the compact and 
low cost RO device or cartridge which need only be replaced once every one 
to six, preferably three days, will help to reduce the cost of treatment 
within the range of a greater number of patients. Furthermore, the PDS 
system 10 will allow for shipment of small volume prepackaged drug 
concentrates in a paste, liquid or dry state which can then be combined 
with the ultrapure water prepared directly at the patient's home site by 
means of the RO device cartridge. 
In an alternative embodiment of the PDS system 10, the operation will be 
computer controlled and will only require an on-off button so that entire 
treatment programs can be implemented from a computer system. Furthermore, 
diagnostic sensors may be included in order to measure the urea and other 
metabolites so as to provide for a constant monitoring and desired 
treatment of the patient. Such a computer system will also permit the 
patient or care giver to modify the treatment stages and the volume of 
treatment fluid as desired. Also, such a computer system will allow the 
treatment process to be fine tuned to the specific medical needs of the 
patient. In general, the PDS system 10 provides a custom care treatment as 
well as an improved quality of life for the patient. 
One specific manner in which the PDS system 10 may control peritoneal 
dialysis is to control the fluid flow rates through pumps 46 and 52. 
Typically, the total volume introduced into the peritoneum is less that 
the total volume drained out of the peritoneum. This volume difference is 
due to the ultrafiltrate or excess water generated in the body which is 
drawn into the peritoneum by osmotic pressure and which contributes to the 
total volume of water draining out. The PDS system 10 may thus set the 
flow through pump 52 at a greater rate than through pump 46 to compensate 
for this volume difference. 
Another manner of controlling the peritoneal dialysis is to set the maximum 
fluid pressure in the inlet line near point A to 48 inches of water and to 
set the outlet line near point B to a maximum of minus 38 inches of water. 
This effectively prevents the pressure within the peritoneum from 
exceeding 30 inches of water. Preferably, the pressure within the 
peritoneum should be less than eight inches of water and most preferably 
less than 5.5 inches of water. These pressure maximums are chosen so as to 
minimize the adverse effect of fluid pressure within the peritoneum to 
cardiac output and vital capacity as disclosed in "Reduction of Vital 
Capacity Due to Increased Intra-Abdominal Pressure During Peritoneal 
Dialysis", by L. Gotloib, et al., P.D. Bulletin, Vol. 1, 63-64 (1981), 
which is incorporated herein by reference. 
As shown in FIGS. 4, 4A and 5, the reverse osmosis (RO) cartridge of the 
present invention has a cylindrical hollow housing 102 forming a chamber 
104 within which a hollow mandrel core 106 open at both ends is disposed 
within the chamber 104 so that the axis of the core 106 is coaxial to the 
axis of the chamber 104. The core preferably is formed of ABS plastic and 
can be molded but preferably extruded. The housing is formed of 
pressure-containing material -steel, fiberglass, Kevlar.TM. or aluminum to 
provide a light yet strong structure. 
As shown in FIG. 14, an RO multilayer assembly 108 includes a porous 
permeate mesh or carrier layer 110, a first RO membrane layer 112, a feed 
water mesh or carrier layer 114 and second RO membrane layer 116. The RO 
membranes 112 and 116 are each formed of a composite, non-porous, 
semipermeable membrane 200, an ultrafiltration membrane 202 and a 
polyamide cloth 204 as shown in FIG. 15. RO membranes of this specific 
structure can be obtained from FilmTec Corporation, a division of Dow 
Chemicals, with a membrane designation of BW30. Such an RO membrane is 
also disclosed in U.S. Pat. No. 4,277,344 of J.E. Cadotte, assigned to 
FilmTec Corporation and issued Jul. 7, 1981 which is incorporated herein 
by reference. The RO multilayer assembly 108 is fixed to and rolled about 
the surface of the core 106 as shown in FIG. 7 and 7A. An impermeable glue 
seal 118 is provided at about the middle of the RO multilayer assembly 108 
prior to rolling and is disposed approximately perpendicular to the core 
106 so that the glue seal 118 separates the RO multilayer assembly 108 
into two stages 120 and 122 when the RO multilayer assembly 108 is 
spirally wound about the core 106. The side edges of the RO multilayer 
assembly 108 are also sealed by glue bonds 118A and 118B. Thus the first 
and second stage 120, 122 are fluidly separated from one another. 
Preferably, the glue seal is made of a transparent glue capable of water 
vapor curing available under a trade name of H. B. Fuller Product 
#UR-0330. In order to provide visibility, the glue can be mixed with a 
coloring agent. Coloring agents include carbon black, fiber glass, mica, 
metallic particles, calcium carbonate and titanium dioxide at 0.25-3% by 
weight of glue preferably less than 1%. Particle size for the coloring 
agent range from 0.1 to 5 .mu.m, preferably 1-2 .mu.m. If carbon black is 
used, the glue becomes gray in color and also results in an improved 
wettability and better bonding. 
The housing 102 has a base 128 which is dimpled inwardly toward the 
interior of chamber 104 as shown in FIG. 4 and 4A. The housing 102 is open 
at its other end which is sealed by a cap assembly 130 that is formed of 
two pieces. In FIG. 4A, the open end of housing 102 is sealed by a 
one-piece plastic cap member 131. In FIG. 4, an integral cap member 132 
made of the same plastic material from which the core 106 is fabricated 
and an annular steel cap plate 136 which at its inner end seals about a 
periphery of cap member 132 and at its outer end seals in a formed manner 
with rolled edge 138 of the housing 102. As shown in FIG. 12, the annular 
steel cap plate 136 provides openings 140a, 142a and 144a for an inlet 
tube 140 of cap 132 which is coupled by suitable tubing (not shown) to the 
high pressure water from pump 20 as shown in FIG. 1; the drain outlet tube 
142 and optionally 147; and a permeate or purified water outlet 144 as 
shown in FIGS. 9, 12A and 5. The radial ribs of the annular steel cap 
plates 136 are optional and are not required. The core 106 contains a 
hollow space 146 to receive therein activated carbon 145 which is held in 
place between depth filters 148 adjacent the base 128 and 150 which is 
adjacent the cap 132. 
The one-piece cap 131 of FIG. 4A is made of a moldable plastic material 
such as that from which the core 106 is fabricated. As shown in FIGS. 4A 
and 12D, overhanging and segmented flanges 133 are fitted on the rolled 
edge 138 of the housing 102. An annular plastic locking ring 135 snaps 
over the flanges to initially lock the cap 131 onto the rolled edge 138 of 
the housing. As seen in FIG. 12E, a gasket and bonding agent applied to 
the circumferential surface of channel 137 formed by flanges 133 and inner 
circumferential flange 139 provides a sealing connection of the cap 131 to 
the housing 102. 
For canisters with large pressure differentials, it is advantageous to use 
the pump which develops the internal pressure to generate an external 
balancing pressure on the cap 131 at F in FIG. 12E to facilitate sealing 
of the cap 131 onto the housing 102. The device is capable of high 
internal hydrostatic pressure with self-sealing characteristics. 
As shown in FIG. 12C, cap 131 provides opening 140b for an inlet tube to 
high pressure water, opening 142b for a first outlet drain and 147b for a 
second outlet drain, and outlet 144b for purified water. 
As shown in FIGS. 7 and 14, a first RO multilayer subassembly 210 at one 
end 212 can be affixed in a longitudinal slot 214 from which the 
multilayer subassembly 210 is spirally wrapped around the core 106. This 
first multilayer subassembly comprises a porous permeate carrier layer 110 
and a first RO membrane layer 112. A second RO multilayer subassembly 216 
can be affixed in a second longitudinal slot 218 and is also spirally 
wrapped around in the same direction as the aforementioned RO multilayer 
subassembly 210. This second RO multilayer assembly 216 comprises a feed 
water mesh layer 114 and a second RO membrane layer 116. At the other end 
of the membrane multilayer subassembly 210, the edge is kept open to allow 
tap water under pressure to enter. The dotted circle 220 indicates the 
actual radius of the complete RO multilayer assembly when wound onto the 
core 106. 
As shown in FIG. 7A, an RO multilayer assembly 211 can be affixed at 
longitudinal slot 215 in core 106 (or alternatively affixed to the surface 
of core 106) and spirally wrapped around the core 106. The multilayer 
assembly 211 comprises a porous permeate carrier layer 110 and a first RO 
membrane layer 112. A second multilayer assembly 213 is affixed radially 
opposite 211 and is spirally wrapped over 211. Assembly 213 comprises a 
feed water mesh layer 114 and a second RO membrane layer 116. The dotted 
circle 221 depicts the outer radius of the complete RO multilayer assembly 
when wound onto the core 106. The outer longitudinal edge of the assembly 
is kept open to allow fluid under pressure to radially enter the spiral. 
The RO device, as shown in FIG. 4 and 4A, also includes a pressurized 
container 166 which is generally cylindrical having a closed end 168 
resting adjacent the dimpled end of base 128 and secured by a hot melt 
glue bead 169. The other end of pressurized container 166 is open and is 
dimensioned so as to receive the rolled RO second stage 122 therein. The 
core 106 or 106A is sonically welded to the inner base wall of the 
pressurized container 166. An O-ring 170 provides additional sealing to 
facilitate the potting of glue seal 119 which is adjacent the glue seal 
118 and the inner wall of pressurized container 166. If desired, 
additional O-rings can be provided as well as other sealing means 
according to methods known to those of the sealing art. For example, an 
adhesive seal can be provided next to the O-ring above the glue seal 118 
and below the 0-ring after assembly within the pressurized container 166. 
In this manner, the second stage 122 is fluidly sealed from the first 
stage 120. The depth filter 148 is pressed in contacting relationship with 
a bead 172 which helps to seat the core 106 within the pressurized 
container 166. However, the passageways 125 are kept spaced from the base 
of pressurized container 166, as shown in FIG. 4, 4B and 12B so that the 
fluid communication of those passageways is maintained with a chamber 174 
formed therein. 
As shown in FIG. 7 and 7A, the core 106 has additional passageways 222 
which are simply provided to lighten the weight of the core 106 and do not 
provide any operational function in the RO device. 
In a preferred configuration, a small RO device may have an effective RO 
membrane surface for each of the stages 120 and 122 of about 0.5 square 
feet to about 1.5 square feet. A large RO device may require substantially 
more surface area ranging up to industrial sizes of hundreds of square 
feet. The rejection rate of the first stage is at least 90%. The rejection 
rate of the second stage is at least 60%. The overall performance of both 
stages in combination will be at least 96% rejection. The operating 
pressures across the membranes of the first and second stages are 
preferably about 125 psi each. The dimension of the housing 102 of the RO 
device is preferably about 7 inches in length, 2.3 inches in diameter. The 
dimension of the hollow core 106 of the RO device is preferably about 6.3 
inches in length and about 1.25 inches in diameter. 
In operation, the various fluid paths of the RO device are illustrated in 
FIG. 6 and 6A, which shows that pressurized tap water enters through inlet 
140 and thereafter through passageway 152. Upon entering the first stage 
120, the pressurized water passes through the spirally rolled reverse 
osmosis multilayer assembly in a generally spiral flow path longitudinal 
passageway 123 and toward the cap member 131 or 132 and thereafter is 
directed by guide 124 through depth filter 150 (See FIG. 4 or 4A) into the 
hollow space 146 containing activated carbon 145. Upon passing through the 
length of the hollow space 146, the now chemically purified water passes 
through depth filter 148 (See FIG. 4 or 4A) and then through guide 125 to 
the chamber 104 from which the chemically purified water enters in the 
spirally rolled reverse osmosis multilayer assembly of the second stage 
122. Upon further filtration in a generally spiral flow path within second 
stage 122, the finally purified water passes into passageway 154 and exits 
through permeate outlet 144. The drain water from the first stage 120 
enters into passageway 156 and then through restrictor 224 as indicated in 
FIG. 7 or 7A and described below in FIGS. 28-31. The second stage 122 
enters into a passageway 158 and then through restrictor 226 as indicated 
in FIG. 7 or 7A and described below in FIG. 28-31. The fluid from 
restrictors 224 and 226 combine within guide 143 and subsequently drains 
through outlet 142. Alternatively, the fluid from the first stage 
restrictor 224 can drain directly through optional outlet 147 and the 
fluid from the second stage restrictor 226 can drain directly through 
outlet 142 as shown in FIGS. 6. 
An alternative embodiment of the RO device according to the present 
invention is illustrated in FIGS. 8-11, wherein structural features common 
to the embodiment shown in FIG. 4 are depicted by the like number. The 
main difference in construction from that shown in FIG. 4 is that the 
first stage 122 is away from the inlet 140 and is fitted against the inner 
wall of the pressurized container 166 and the second stage 120 is closest 
to the inlet 140. 
In operation, the various fluid paths of the alternate RO device are 
illustrated in FIG. 10, which shows that pressurized tap water enters 
through inlet 140 and thereafter through passageway 123 within core 106. 
Upon approaching the base 128 of pressurized container 106 the pressurized 
water enters through guide 125 into passage chamber 174 and thereafter 
into the RO multilayer assembly of the first stage 122. The first portion 
of purified water from the tap water is passed into the longitudinal 
passageway 146 and back toward the base 128 which thereupon admits through 
guide 126 the first purified portion into the hollow space 146 containing 
activated carbon 145 within the hollow core 106. Upon passing through the 
length of the hollow core 106, the now chemically purified water enters 
the chamber 104 through guide 127 from which the chemically purified water 
enters into the RO multilayer assembly of the second stage 120. Upon 
further filtration within second stage 120, the finally purified water 
passes into passageway 156 and exits through outlet 144. The drain water 
from the first stage 122 enters passageway 158 and then through a 
restrictor as described below in FIG. 28-31. The drain water from the 
second stage 120 enters passageway 154 and then through another 
restrictor. The fluid from both restrictors combine within guide 143 and 
subsequently drains through outlet 142. Alternatively, the fluid from the 
first stage restrictor can drain directly through another outlet (not 
shown) and the fluid from the second stage restrictor can drain directly 
through outlet 143. 
In both of the above embodiments shown in FIGS. 4 and 8, the RO multilayer 
assembly which is wound about the hollow core 106 is attached onto the 
core 106 by means of two slots 214 and 218 as shown in FIGS. 7 and 13. 
Preferably, one or more of the ends of the RO multilayer assembly is 
attached to the hollow core 106 by means of an adhesive strip 228 without 
placing the end into any slot as shown in FIG. 11. The RO multilayer 
assembly is thereby divided into two parts in its attachment to the core 
106. FIG. 14 schematically illustrates the various layers of the RO 
multilayer assembly. As shown in FIG. 13, the first part which is attached 
to slot 218 comprises a porous mesh layer 114 and a second RO membrane 
layer 116. The second part which is attached to slot 214 comprises a 
porous permeate layer 110 and a first RO membrane layer 112. In operation, 
the unpermeated tap water is drained out from the porous mesh layer 114 
and through passageways 158 and 156 within core 106 to drain outlet 142. 
The purified water which has permeated through the RO membrane layer 112 
and 116 passes from the porous permeate layer 110 through passageways 123 
and 154 within the core 106 and to permeate outlet 144. 
Preferably, as shown in FIG. 7A, for the embodiment of FIG. 4A, the 
multilayer assembly may be attached onto the core 106 at a single slot 215 
or attach to the hollow core 106 at a single position by attachment such 
as adhesive tape. 
As best seen in FIG. 7B, radial holes 156A and 158A provide fluid passage 
for the waste fluid in the spiral flow to waste passages 156 and 158. 
Similarly, radial holes 123A and 154A provide fluid passage for the 
purified fluid in the RO membrane spiral flow to the purified passageways 
123 and 154. 
When the multilayer is wound about the core, the RO multilayer assembly is 
configured as shown in FIG. 14. The first and second RO membrane layers 
112 and 116 are faced in opposite directions from each other because of 
the structure of the RO membrane layer which is shown in FIG. 15. Adhesive 
beads 206 are disposed against the porous mesh layer 114 and the porous 
permeate layer 110 as shown to form the RO multilayer assembly. The RO 
membrane layers 112 and 116 comprise a nonporous, semipermeable membrane 
200 an ultrafiltration membrane 202 and a polyamide cloth 204 as shown in 
FIG. 15. The RO membrane layers 112 and 116 in FIG. 14 illustrate the 
relative position of the nonporous, semipermeable membrane 200 with 
respective to the other layers. Specifically, the nonporous, semipermeable 
membrane layers of the RO membrane layers 112 and 116 are adjacent to the 
porous mesh layer 114. 
Another alternative embodiment of the RO device according to the present 
invention is illustrated in FIG. 16, wherein structural features common to 
the embodiment shown in FIG. 4 are depicted by like number. As shown in 
FIG. 16, the RO device 400 has a central core 106 which is positioned 
within an end base cap 402 and secured to adjacent base 128 of housing 102 
by hot melt glue bead 169. As shown in FIG. 17, four RO multilayer 
subassemblies 316, 318, 320 and 322, are affixed in longitudinal slots 
324, 326, 328 and 330, respectively, in core 106. Alternatively, the ends 
of the subassemblies may be attached to the core by adhesive beads. RO 
multilayer subassembly 316 is formed of a nonporous, semipermeable 
membrane layer 302 and a porous permeate layer 304. The RO multilayer 
subassembly 318 is similarly formed of a nonporous semipermeable membrane 
layer 306 and a porous permeate layer 308. Likewise, the RO multilayer 
subassembly 320 is similarly formed of a nonporous semipermeable membrane 
layer 310 and a porous permeate layer 312. The RO multilayer subassembly 
322 is formed of a nonporous semipermeable membrane layer 314 and a porous 
mesh layer 300. Unpermeated tap water exits through passageway 158 and 
drain outlet 142 and sterilized water exits through passageway 123 and 
permeate outlet 144. As shown in FIG. 18 which is taken in the opposite 
direction of FIG. 17, the RO membranes 302, 306, 310 and 314 are spirally 
wound around the core 106 as well as each other. Alternatively, FIG. 18 
represents an RO configuration in which the RO membranes, if desired, can 
be rolled about core 106 in the opposite direction to that shown in FIG. 
17. Interleaved between the RO membranes are the porous mesh layer 300 and 
the porous permeate layers 304, 308 and 312. When the static pressure 
within the porous mesh layer 300 is TP, the static pressure within the 
porous permeate layers 304 and 312 is 1/2 TP and the static pressure 
within the porous permeate layer 308 is about 0.05 TP. The various flow 
paths are shown in FIG. 18 as well. In operation, the alternative 
embodiment of the RO device of FIG. 16-19 is substantially the same as 
that described with reference to the RO device illustrated in FIGS. 4 and 
8. However, the alternative RO device of FIG. 18 passes the water from the 
high pressurized source through the two RO stages which are formed of the 
four RO multilayer subassembly of FIG. 17 before passing through the 
activated carbon 145 contained in the hollow space 146 within core 106 
between depth filters 148 and 150. An exploded cross-sectional view of the 
RO multilayer assembly of FIG. 18 is shown in FIG. 19. Adhesive beads 206 
are disposed against the layers as shown to form the RO multilayer 
assembly. 
The activated carbon 145 serves to remove chloramine as well as dissolved 
gases from the tap water. In the event that the water supplied to the RO 
device is already free of chloramines, then there is no need to chemically 
treat the water. In addition, chemical treatments can be utilized for 
removal of other chemical species as well. Both the semipermeable 
membranes in the RO device of FIG. 4 or 4A and the alternative embodiments 
of FIGS. 8 and 16 are preferably formed of polyamide. However, other 
semi-permeable membrane layers can be utilized as well. 
In both embodiments of the RO device as illustrated and described herein, 
the RO membranes are formed in a spiral configuration so as to maximize 
the velocity of tap water across the membrane and to minimize the 
concentration polarization at the membrane surfaces within as small and 
compact a housing as possible. This avoids the need to provide for 
extensive lengths of housing to enclose RO membranes as found in typical 
applications. 
Yet another alternative embodiment of the RO device according to the 
present invention is illustrated in FIG. 20. The RO device 702 includes a 
generally cylindrical housing 704 having an end cap 706 in which is 
disposed centrally an inlet port 708 that is fluidly coupled to the source 
of water to be purified. The other end has a seal cap 710 that is screwed 
on by threads which engage cooperating threads 712 on the adjacent end 
portion of housing 704. The seal cap 710 has a waste outlet 714 and a 
permeate outlet 716. Positioned internally within the housing 704 is a 
core 701 that is generally cylindrical and is formed of three longitudinal 
passageways as shown in FIG. 20A. Two of the passageways 720 and 722 are 
of like shape and together form half of the core 701. The remaining 
passageway 724 includes activated charcoal for the same purposes as 
discussed above in connection with the prior embodiments. Passageway 720 
is coupled through outlet 714 for passage of waste water. The other like 
passageway 722 provides for passage of permeate and is coupled to the 
outlet 716 in seal cap 710. A first RO stage 726 is positioned within 
chamber 728 formed within housing 704. The second stage 729 is positioned 
within housing 704 in chamber 730 adjacent seal cap 710. The first and 
second stages are connected through a restrictor 705. The restrictor 705 
is designed to adjust the backpressure within the first and second stages 
726 and 729 so as to provide the desired water flow rate across the 
membranes. The first and second RO stage's 726 and 729 are separated by a 
core support carrier 732 which is snugly fit within housing 704. The 
support carrier 732 has a U-shaped channel 734 that extends along the 
periphery of carrier 732 to receive an O-ring 736 as shown in FIG. 20. In 
operation, water enters through port 708 and into chamber 728 wherein it 
enters into the first RO stage 726. After filtration, the filtered portion 
of the water passes through radial openings 741 in core 701 into 
passageway 724. Upon passing through the activated charcoal 718 within 
passageway 724, the partially filtered water passes through radial opening 
740 in core 701 into chamber 730 and from there into the second RO stage 
as shown in FIG. 20. Upon further filtration, the permeate passes out 
through outlet 716. The waste water from the first stage passes through 
radial openings 742 into the return passageway 720 and from the second 
stage through radial opening 744 also into the waste passageway 720 and 
finally out the waste outlet 714. 
In yet another alternative embodiment of the RO device according to the 
present invention as shown in FIG. 21, the RO device 802 includes a 
cylindrical housing 804 that includes a first RO stage 806 and a second RO 
stage 808 which are wrapped around a central core 810. The central core 
810 has an inlet port 812 through which water passes into an interior 
chamber 814 and thereafter through openings 816 into the chamber 818 in 
which the first stage 806 is positioned. Upon passing through the first 
stage 806, the filtered water passes through radial opening 820 in core 
810 and thereafter through radial opening 822 into a central portion 
containing activated charcoal 823. Upon passing through the charcoal 823, 
the purified water passes out through radial opening 824 into chamber 826 
and through radial opening 828 in core 810 through antechamber 830 and 
therefrom through opening 832 into chamber 834 in which the second RO 
stage 808 is positioned. Upon passage through the second RO stage, the 
permeate exits through radial opening 836 and out through port 838. The 
waste water from the first RO stage exits through drain port 840 while the 
waste water from the second RO stage 808 passes through the drain port 
842. 
In order to provide for proper water flow across the RO multilayer assembly 
108, the cylindrical passageway tubes in core 810 are designed in 
accordance with the Bernoulli equation so that their diameter and length 
are calculated to produce a static pressure drop across both RO multilayer 
assemblies 108 of the first stage 806 and second stage 808. The pressure 
drop produces the desired water flow rate across the membranes. For 
example, the flow across the second membrane is less than across the 
first. Static pressure across the first membrane is twice that across the 
second. This yields a different geometry for the second restrictor. 
Balancing the spiral resistance with the cylindrical resistance is the key 
to the proper functioning of the RO Device. 
FIGS. 28 and 29 illustrate a linear restrictor having a barrel 522 and a 
needle 520 of proper internal diameter and path length to produce the 
required static pressure drop across both RO multilayer assemblies. FIGS. 
30, 30A and 31 illustrate a helical restrictor which serves the same 
function. The advantage of the helical restrictor 524 is that the path 
length along the restrictor 524 within sleeve 526 can be manually adjusted 
by screwing the restrictor 524 further into or out of the sleeve 526 by 
way of a slot 528. The dimension of the helical restrictor 524 is 
preferably about 1 inch in length, 0.150 inch in diameter with about 16 
threads per inch and a thread width of 0.020 inch. The effective path 
length of such a helical restrictor 524 is therefore in the range of at 
least six times the actual length. The restrictors are disposed within the 
passageways which fluidly connects the drains 156 and 158 of RO multilayer 
assemblies of the first and second stage. Alternatively, the restrictor 
may be placed at the outlet drain of stage one and the outlet drain port 
of the device. The helical path flow restrictor of FIG. 30A is are further 
discussed in commonly assigned, copending U.S. patent application Ser. 
No.(Docket No. 4827.US.P3) filed Mar. 3, 1992, entitled "Helical Path Flow 
Restrictor" which is hereby incorporated by reference. 
In the operation of the present peritoneal dialysis system (PDS) 10 of the 
present invention, the potable water can be heated to about 40.degree. C. 
before passing through the RO device 22 as shown in FIG. 1. The higher 
temperature increases the efficiency of the reverse osmosis process. 
Specifically about 600 ml/min of potable water can be heated from about 
20.degree. C. to about 70.degree. C., preferably up to 40.degree. C. In 
order to decrease the heating demand on heater 18, the heat exchanger 16 
transfers heat from the waste water from RO device 22 and patient 50 to 
the potable water before the potable water passes through heater 18. 
The configuration of the heat exchanger 16 is similar to that of the RO 
device 22 but only requires thin non-permeable membrane multilayer 
assemblies with porous spacers spirally wound about a hollow core 602 as 
shown in FIG. 22. Specifically, the heat exchanger 16 contains a first 
multilayer assembly 604 as shown in FIG. 23 which includes a first porous 
spacing layer 606 and a non-permeable membrane layer 608. Adhesive beads 
610, 612 and 614, preferably of RTV silicon, are applied along the side 
edges as shown in FIG. 24. A partial adhesive bead 616 is applied to the 
free end along a portion thereof. A second multilayer assembly 618 shown 
in FIG. 25 includes a second porous spacing layer 620 and a non-permeable 
membrane layer 622 that are disposed on the first multilayer assembly 604 
such that the first and second porous spacing layers 606 and 620 are 
interleaved between the two non-permeable membrane layers 608 and 622. 
Adhesive beads 624, 626 and 628, also preferably of RTV silicon, are 
applied along the side edges of multilayer assembly 618 as shown in FIG. 
26. A partial adhesive bead 630, oppositely disposed to partial adhesive 
bead 616 in FIG. 24, is applied to the remaining free end of multilayer 
assembly 618 along a portion thereof. 
As shown in FIG. 22, the first and second multilayer assemblies 604 and 618 
are wrapped about core 602, preferably made of ABS plastic, and are 
imbedded within the pressurized container 632 which is similar to 
container 166 in the RO device of FIG. 4. The end cap 634 seals the heat 
exchanger unit 16 within a housing (not shown). An O-ring 636 helps to 
seal the unit 16 within the pressurized container 632. The RTV silicon 
sealant is shown generally in the assembled form in FIG. 22 at 638. The 
hot waste water enters through part 640 and cold discharge water exits 
through port 642 after passing through longitudinal passageway 644. Radial 
holes 646 in the core 602 admit the spent or cold waste water from between 
the membrane multilayer assemblies into the passageway 644. Cold potable 
water enters through port 647. Hot potable water which has received heat 
transferred from the hot waste water between the membrane multilayer 
assemblies passes through port 648 in cap 634 after exiting through radial 
holes 650 in core 602. 
In operation, hot waste water passes through the first porous spacing layer 
while tap water passes through the second porous spacing layer. The 
transfer of heat from the hot waste water to the potable water occurs 
across the non-permeable membrane layers as the waste and the potable 
water flow spirally in a countercurrent or concurrent flow path. The 
porous spacing layer is preferably polypropylene mesh. The non-permeable 
membrane layer is preferably a polyester film such as Melinex.RTM. or a 
foil, preferably metallic. 
Heat transfer efficiency of the heat exchanger 16 is dependent on the 
membrane material used, the water flow path width, the path length as well 
as the amount of area available for heat transfer. Consideration of heat 
transfer efficiency, however, must be balanced with the unfavorable 
pressure drop through the heat exchanger 16. A preferred configuration has 
a heat transfer area of about 300 sq. inches and a pressure drop of about 
4 psi at 600 ml/min flow rate. 
A more general illustration of the use of the RO device is presented in 
FIG. 27 which illustrates a source of fluid or water 500 which is passed 
on to a RO device 502. Here again, the waste fluid is passed on to a drain 
504 while the purified fluid is passed on to a concentration, mix, store 
and/or control system 506. Storage can be provided in suitable bags which 
thereafter can be utilized when desired for the patient 508 or other end 
uses 510. If denied, a portion of the purified fluid after use can be 
returned to the source along fluid path 512. Similarly, some or all of the 
waste from the RO device 502 can also be returned to the source and 
thereafter passed on for purification within the RO device 502. 
According to the preferred design, the RO cartridge may be used for three 
to six days during a weekly treatment and thereafter is discarded. 
Discarding the cartridge is necessary because of carbon contamination 
buildup and to avoid a sterility breach. For this reason, there is no need 
to sterilize while in use the RO membranes so as to remove any 
contaminants whether chemical or particulate as is required with present 
systems. In order to provide an RO cartridge suitable for home use, the RO 
cartridge is designed for optimization of compactness and space as well as 
performance so as to minimize the cost. This will enable the patient to 
obtain home treatment without the need to stock a large quantity of 
sterile water and also further avoids the need to provide for multiple 
hook-ups as is required in the case of CAPD treatment. Discussion of the 
concerns and problems relating to connection to multiple water bags is 
presented in an Optum.RTM. brochure entitled "The Hands-Free Exchange For 
Your CAPD Patients" and U.S. Pat. No. 4,840,621 which are incorporated 
herein by reference. 
By means of the use of a dual RO stage system, less expensive RO membrane 
multilayer assemblies can be utilized so as to still obtain preferably at 
least a 96% rejection rate. Moreover, the dual RO multilayer assemblies 
provide a redundancy which is medically desired in the event that one 
membrane fails. The drastic medical consequences of introducing pyrogen, 
virus or bacteria in the peritoneal cavity are thus avoided by the present 
RO device. 
The RO device and system of the present invention accordingly overcome the 
problems of known filtration devices for use in peritoneal dialysis and 
provide sterile water solutions suitable for peritoneal dialysis and other 
uses as well and which can easily maintain the desired sterile conditions. 
Because of the modular design of the present system, the reverse osmosis 
device and other system components which are in contact with the water can 
be periodically disposed of and replaced by new sterile components. The 
need to have a complicated method of sterilization implemented by the user 
is therefore avoided. 
FIG. 32 illustrates one efficient manner of producing the RO device of the 
present invention. Specifically, electromagnetically activatable adhesive 
beads are applied onto the porous mesh layer and the porous permeate 
carrier layer along the edge and the middle of the multilayer assembly as 
shown. The manner in which the adhesive bead is applied can be by a roller 
coating method in which the adhesive is heated in a pot and picked up by a 
transfer roller (not shown). The transfer roller then prints the adhesive 
strips 206 onto the porous mesh layer or the porous permeate carrier layer 
(see FIGS. 14 and 19) in a continuous manner as the layers move across the 
transfer roller. The layers are then combined and rolled onto a hollow 
core 106. Simultaneous to the rolling of the layers to form the multilayer 
assembly, the adhesive strips 206 are heated by the induction coils 528. 
The softened adhesive strips 206 then bond the RO multilayer assembly 
together as the adhesive cools within the wound layers. 
A representative example of such an electromagnetically activatable 
adhesive may be obtained from Emabond Systems of Ashland Chemical Company, 
a division of Ashland Oil, Inc. and is taught in U.S. Pat. No. 3,620,875, 
issued Nov. 16, 1971 which is incorporated herein by reference. 
FIG. 33 illustrates another manner of producing the RO device of the 
present invention. The adhesive bead 200 has already been applied to the 
mesh and permeate layers of the RO multilayer assembly. The assembly 108 
is subsequently wound about the hollow core 106 and then inserted into a 
flexible silicone bladder 530 and attached to cap 532 by ring 534. The 
wound assembly is then evacuated by vacuum 536 to thereby ensure close 
contact between the layers of the assembly and the core 106. Induction 
heating is then applied by coils 538 while the assembly is in the 
evacuated state so as to bond the layers together. The vacuum in bladder 
530 is released by filtered air from 540 after cooling of the adhesive 
bead has occurred. 
FIG. 34 illustrates a method of attaching the integral cap member 132 of 
the RO device to the hollow core 106 by sonic welding. The ultrasonic 
vibration of the sonic horn 550 is transmitted through energy transmission 
guides 552 to energy directors 554 so as to focus the vibration energy to 
the point of contact with the hollow core 106. Additionally, another sonic 
horn 556 is used to sonically weld the inner base wall of the pressurized 
container 166 to the other end of the hollow core 106 through similar 
energy transmission guides 558 and energy directors 560. Alternatively, 
the energy directors may be placed on the hollow core 106. Such 
directional welding can be accomplished at 20 and 40 kHz frequencies. 
FIGS. 12A and 12B illustrate the energy directors 554 and 560 respectively 
in a ridge design so as to seal the passageways of the hollow core to the 
integral cap member 132 and inner base wall of the pressurized container 
166 as shown in FIG. 4. The pattern shown in FIG. 12A and B allows for the 
sealing of the passageways of the core to the guides of the cap so as to 
provide fluid passageway inner connections. 
The ridge design of the integral cap member 132 shown in FIG. 12A is 
adapted to provide the RO device of FIG. 6 with the guide 124 connecting 
passageway 123 and hollow space 146; guide 143 connecting passageways 156 
and 158 to waste drain outlet 142; the connection between inlet hole 140 
and passageway 152; and the connection between permeate outlet hole 144 
and passageway 154. 
The ridge design of the cap member 131 shown in FIG. 12D is adapted to 
provide the RO device of FIG. 6A with an open guide 124A connecting 
passageway 124 having the purified water of first stage RO with the hollow 
space 123 containing the activated carbon 145. Raised guides 143A and B 
connects first and second stage RO waste passageways 142b and 147b. The 
open guide 155 connects inlet hole 140b with inlet passageway 152 to the 
first stage RO. Raised guide 157 connects permeate outlet hole 144b with 
passageway 154 from the second stage RO purified passageway. 
The ridge design of the inner base wall of the pressurized container 166 
shown in FIG. 12B is adapted to provide the RO device of FIG. 6 and 6A 
with guides 159 so as to seal the ends of the passageways of the core 106. 
Guide 125 connects the hollow space 146 of the core 106 or 106A to the 
chamber 104 which allows the chemically purified water to enter from the 
hollow space 146 to the RO multilayer assembly of the second stage 122. 
The present invention has been described in detail with particular emphasis 
on the preferred embodiments thereof. However, it should be understood 
that variations and modifications may occur to those skilled in the art to 
which the invention pertains.