- Email: [email protected]
A water purification system for laboratory use
Clin. Biochem. 11, (4) 18_3-184 (1978)
A Water Purification System for Laboratory Use J. BERTSCH, M. MARTINUS, D. ZIMBER, N. KUBASIK and H. SINE* Clinical Laboratories, The Genesee Hospital, 224 Alexander Street, Rochester, New York 14607 (Accepted February 10, 1978) CLBIA, 11 (4) 183-184 (1978) Clin. Bioohem. Bertsch, J., Martinus, M., Zimber, D., Kubasik, N., and Sine, H.
Clinical Laboratories, The Genessee Hospital, ~ 4 Alexander Street, Rochester, New York, 14607 A WATER PURIFICATION SYSTEM FOR LABORATORY USE A water purification system is described, capable of producing Type I water upon demand at multiple locations up to 700 feet, from the purifying equipment. Tap water is initially treated employing reverse osmosis, followed by treatment with activated charcoal and mixed anion/cation exchange resins. The resultant Type I quality water is miantained by means of a recycling loop until removal upon demand. The current cost of producing water of this quality is $0.03 per liter, exclusive of capital and installation costs.
THE NEED FOR WATER OF INCREASING PURITY has become n e c e s s a r y with the i n c r e a s e d s e n s i t i v i t y of m a n y l a b o r a t o r y d e t e r m i n a t i o n s and t h e i r suscept i b i l i t y to c o n t a m i n a t i o n . However, t h e r e is little i n f o r m a t i o n a v a i l a b l e to d e m o n s t r a t e an exact relat i o n s h i p of the w a t e r q u a l i t y need, r e l a t i v e to a specific a s s a y p r o c e d u r e . The College of A m e r i c a n P a t h o l o g i s t s (CAP) and the N a t i o n a l Committee f o r Clinical L a b o r a t o r y S t a n d a r d s (NCCLS) have o f f e r e d g u i d e l i n e s f o r w a t e r use in the clinical l a b o r a t o r y TM ~). The NCCLS and CAP g u i d e l i n e s s u g g e s t the use of two and three w a t e r g r a d e s respectively, in the laboratory. Type I w a t e r to be used where m a x i m u m a c c u r a c y and p r e c i s i o n is r e q u i r e d . Type II f o r g e n e r a l labor a t o r y t e s t i n g (and g l a s s w a r e r i n s i n g in the case of the NCCLS s t a n d a r d s ) . Type III, d e l i n e a t e d by CAP f o r use in q u a l i t a t i v e a n a l y s i s and g l a s s w a r e rinsing. A s u m m a r y of p r i m a r y s p e c i f i c a t i o n s for these w a t e r t y p e s is given in T a b l e s 1 and 2. In this r e p o r t , we d e s c r i b e a c e n t r a l p u r i f i c a t i o n s y s t e m c a p a b l e of p r o v i d i n g Type I w a t e r to mult i p l e locations. MATERIALS
Corporation, Bedford, Ma. 01730. The water polishing unit was modified by replacing the prefiltration unit with an additional ion-exchange cartridge. A 150 gallon polyethylene tank for storage of dialized water was obtained from The Nalge Corporation, Rochester, N.Y. 14622. Pressure regulator (FC-PR-50), pressure by-pass calve (FC-PPP-75), and water low-level sensing switch (FC-MM-BR) were obtained from Alloy Supply Co., Inc., Rochester, N.Y. 14625. All piping was Type I, grade 1, polyvinyl chIoride (PVC), ~ inch and the reagent water taps were constructed of polypropylene (Sloan & Co., Rochester, N.Y. 14623). The remote resistivity measuring system (conductivity meter, model 900M-18M and conductivity cell, 900-01T) were obtained from Balsbough Lab Inc., S. Hingham, Ma. 02043. A centrifugal high pressure pump (10B 58 SS) was obtained from Weber Industries, Inc., St. Louis, Mo. 63123). A leak detection system with sound alarm and automatic tap water shutdown was designed and built by one of the authors (M. M.)C3~. RESULTS AND DISCUSSION A d i a g r a m of the w a t e r p u r i f i c a t i o n s y s t e m is shown in F i g u r e 1. The s y s t e m is located in a maint e n a n c e a r e a remote from the l a b o r a t o r y , which e l i m i n a t e s pump noise exposure to the personnel. M u n i c i p a l d r i n k i n g w a t e r at 60 p o u n d s / s q u a r e inch (psi) serves as a feed s u p p l y for the system. The p r e f i l t e r (A) removes p a r t i c u l a t e m a t t e r f r o m the feed w a t e r which extends the life of the d i a l y s i s m e m b r a n e . A t a line p r e s s u r e of 60 psi, the r e v e r s e osmosis, (RO) u n i t (A) g e n e r a t e s dialyzed w a t e r a t a r a t e of 7 l/h, a booster pump increases the feed w a t e r p r e s s u r e to 200 psi, r e s u l t i n g in an i n c r e a s e d o u t p u t of 27 1/h. The dialyzed w a t e r is s t o r e d in a 150 gallon r e s e r v o i r (B). The q u a l i t y of this w a t e r is c o m p a r a b l e to t h a t of s i n g l y d i s t i l l e d water, according to the m a n u f a c t u r e r (5~. We have confirmed t h a t the specific r e s i s t a n c e is 0.025-0.5 megohms as s p e c i f i e d by the m a n u f a c t u r e r . A c i r c u l a t i n g pump (C) w i t h d r a w s the d i a l y z e d w a t e r f r o m the r e s e r v o i r into a closed c i r c u l a t i n g
A
¢
The reverse osmosis (RO) system (Milli-R040, I-Z R2000052), final water polishing unit (Super-Q ZD 00022S4), Reverse Osmosis Prefilters (CDPR-012-04), Ion Exchange Cartridges (CDMB-022-02), Super-C Carbon Cartridges (CEAC-022-02), and Millipore Membrane Filters (CFRA-022-05), were obtained from Millipore Presented in Part at the Twentieth Annual Meeting and Conference of the Canadian Society of Clinical Chemists, Ottawa, Canada, July 1976. *Inquiries to be directed to H. E. Sine.
Fig. 1 - - Schematic illustration of the water purification system. A) Reverse Osmosis Unit, B) Storage Reservoir, C) Circulating Pump, D) Flow Regulator, E) Charcoal/ Resin~Filter Polishing Unit, F) On Line Monitor, G) Water Taps.
BERTSCH, MARTINUS, ZIMBER, KUBASIK AND SINE
184
TABLE 1 SUMMARY OF THE COLLEGE OF AMERICAN PATHOLOGISTS REAGENT W A T E R SPECIFICATIONS
MINUMUM REQUIREMENTS
TYPE I
TYPE IT
TYPE n l
SPECIFIC RESISTANCE
(Megohms, Minimum) ....
i0
SILICATE
(rag/L, Maximum) . . . . . . .
HEAVY METALS
(mg/L, Maximum) . . . . . . .
0.5
0.2
0.01
0.01
0.01
0.01
0.01
0.01
COLOR RETENTION TIME OF PERMANGANATE
(Minutes, Minimum) . . . . .
60
SODIUM
(rag/L, Maximum) . . . . . . .
HARDNESS AMMONIA
(mg/L, Maximum) . . . . . . .
CULTURE COLONY COUNT
60
60
0.1
0.1
0.1
NEG
NEG
NEG
0.1
0.1
0.I
MINIMUM GROWTH
MINIMUM GROWTH
MINIMUM GROWTH
6.0-7.0
6.0-7.0
6.0-7.0
3
3
pH . . . . . . . . . . . . . . . . . . . . . CO2 (mg/L, Maximum) . . . . . . .
3
TABLE 2 SUMMARY OF THE NATIONAL COMMITTEE FOR LABORATORY STANDARDS PROPOSED REAGENT W A T E R SPECIFICATIONS
PARAMETER
TYPE I
TYPE II
10 4
105
MICROBIOLOGICAL CONTENT
(Colonies/l, Maximum) TOTAL BACTERIAL COUNT . . . . . . PARTICULATE MATTER,
microns (Maximum Size) . . . . .
1.0
1.0
PERMANGANATE TIME
(minutes, Minumum) at 25°C.. pH . . . . . . . . . . . . . . . . . . . . . . . . .
60 N.A.
10 5.5-7.5
RESISTIVITY,
(megohms-cm, 25°C) . . . . . . . . .
10
0.5
SILICATE,
(mg/l SiO~, Maximum) . . . . . . .
0.05
0.1
loop. A r e g u l a t i n g valve (D) maintains a pump outlet pressure of 40 psi. Subsequent to the regulator valve an unloader valve assures that in case of regulator failure, a pressure rupture will not occur by diverting water at a pressure greater than 50 psi from the circulating loop and r e t u r n i n g it to the reservoir. (Line pressure checks indicate a tolerance to 100 psi). Next the dialysis w a t e r enters the polishing unit (E) at 40 psi where it flows t h r o u g h a column of activated charcoal which absorbs organic macromolecules. The water then passes t h r o u g h two columns of mixed a n i o n / c a t i o n resins in a deionization process and is then t r a n s p o r t e d through a filter cartridge having a pore size of 0.22 microns which removes any bacteria and resin particles. The resultant water is of Type I quality ~4,~ at a line pressure of approximately 20 psi. The w a t e r now enters the main laboratory, where line pressure and resistivity are continuously monitored (F). The unit is located for easy accessibility by lab staff. In addition to continuous monitoring, a low resistivity valve ( ~ 1 5 megohms) activates a warning light. The water is made available to each work area
(14 locations) upon demand t h r o u g h polypropylene faucets connected in series (G). Resistivity measurements conducted at each of the f a u c e t locations indicate that no measurable water quality deterioration occurs. Unused water continues t h r o u g h the circulatory loop, re-entering at the circulating pump (between points C and D). The unused water again re-enters the polishing unit, assuring constant availability of Type I water. When water is drawn from the system, dialyzed water from the reservoir (B) replenishes the loss. A low water level sensing switch, located in the base of the reservoir disconnects the circulating pump if the water level drops below five gallons. This prevents pump burnout. The entire system requires minimal maintenance. Line pressure, resistivity, and water usage are observed and recorded daily. Replacement of all cartridges on the polishing unit is necessary upon the generation of about 6,500 liters of Type I water. The RO filter change is made when the tap water and RO pressure differential is 10 psi, about every 10-15 days. An average pass volume of tap water is about 2,500 liters per RO filter change. The RO dialysis membrane cartridge requires replacement when its output drops 3 1/h at feed water pressure of 60 psi. This occurs approximately every 12 months. The dialysis water reservoir requires occasional cleaning due to algae growth, primarily during the summer months. The water system is shut down, reservoir tank drained, and washed with household bleach. The reservoir is thoroughly rinsed with tap water and RO water prior to activation of the water system. The frequency of cleaning the reservoir is every 12 months. Current Type I water consumption averages about 270 liters per day. Operational costs which include cartridge replacement and yearly RO dialysis membrane change is $0.03 per liter. We have satisfactorily employed this system for nearly three years in our laboratory. ACKNOWLEDGEMENT We wish to thank Art Carafos for his assistance in the construction of the water system. R~FERENCES 1. Stier, A., Miller, L., and Smith, R., Reagent-Water, Specifications and Methods of Quality Control, College of American Pathologists, Commission on Laboratory Inspection and Accreditation. Skokie, Ill. (1976). 2. Reagent Water Specification and Test Methods for Water Used in the Clinical Laboratory. National Committee for Clinical Laboratory Standards, Villanova, Pa. (1976). 3. Martinus, M., Unpublished Results. 4. Weisbrat, I., Evaluation of the Milli-Q3/MillioQ2 Reagent Water System, Bulletin Millipore Corp., Bedford, Mass. (1974). 5. Knott, A., Investigation of a High Purity Water System, Atomic Adsorption Newsletter 14, 126 (1975).
A Water Purification System for Laboratory Use J. BERTSCH, M. MARTINUS, D. ZIMBER, N. KUBASIK and H. SINE* Clinical Laboratories, The Genesee Hospital, 224 Alexander Street, Rochester, New York 14607 (Accepted February 10, 1978) CLBIA, 11 (4) 183-184 (1978) Clin. Bioohem. Bertsch, J., Martinus, M., Zimber, D., Kubasik, N., and Sine, H.
Clinical Laboratories, The Genessee Hospital, ~ 4 Alexander Street, Rochester, New York, 14607 A WATER PURIFICATION SYSTEM FOR LABORATORY USE A water purification system is described, capable of producing Type I water upon demand at multiple locations up to 700 feet, from the purifying equipment. Tap water is initially treated employing reverse osmosis, followed by treatment with activated charcoal and mixed anion/cation exchange resins. The resultant Type I quality water is miantained by means of a recycling loop until removal upon demand. The current cost of producing water of this quality is $0.03 per liter, exclusive of capital and installation costs.
THE NEED FOR WATER OF INCREASING PURITY has become n e c e s s a r y with the i n c r e a s e d s e n s i t i v i t y of m a n y l a b o r a t o r y d e t e r m i n a t i o n s and t h e i r suscept i b i l i t y to c o n t a m i n a t i o n . However, t h e r e is little i n f o r m a t i o n a v a i l a b l e to d e m o n s t r a t e an exact relat i o n s h i p of the w a t e r q u a l i t y need, r e l a t i v e to a specific a s s a y p r o c e d u r e . The College of A m e r i c a n P a t h o l o g i s t s (CAP) and the N a t i o n a l Committee f o r Clinical L a b o r a t o r y S t a n d a r d s (NCCLS) have o f f e r e d g u i d e l i n e s f o r w a t e r use in the clinical l a b o r a t o r y TM ~). The NCCLS and CAP g u i d e l i n e s s u g g e s t the use of two and three w a t e r g r a d e s respectively, in the laboratory. Type I w a t e r to be used where m a x i m u m a c c u r a c y and p r e c i s i o n is r e q u i r e d . Type II f o r g e n e r a l labor a t o r y t e s t i n g (and g l a s s w a r e r i n s i n g in the case of the NCCLS s t a n d a r d s ) . Type III, d e l i n e a t e d by CAP f o r use in q u a l i t a t i v e a n a l y s i s and g l a s s w a r e rinsing. A s u m m a r y of p r i m a r y s p e c i f i c a t i o n s for these w a t e r t y p e s is given in T a b l e s 1 and 2. In this r e p o r t , we d e s c r i b e a c e n t r a l p u r i f i c a t i o n s y s t e m c a p a b l e of p r o v i d i n g Type I w a t e r to mult i p l e locations. MATERIALS
Corporation, Bedford, Ma. 01730. The water polishing unit was modified by replacing the prefiltration unit with an additional ion-exchange cartridge. A 150 gallon polyethylene tank for storage of dialized water was obtained from The Nalge Corporation, Rochester, N.Y. 14622. Pressure regulator (FC-PR-50), pressure by-pass calve (FC-PPP-75), and water low-level sensing switch (FC-MM-BR) were obtained from Alloy Supply Co., Inc., Rochester, N.Y. 14625. All piping was Type I, grade 1, polyvinyl chIoride (PVC), ~ inch and the reagent water taps were constructed of polypropylene (Sloan & Co., Rochester, N.Y. 14623). The remote resistivity measuring system (conductivity meter, model 900M-18M and conductivity cell, 900-01T) were obtained from Balsbough Lab Inc., S. Hingham, Ma. 02043. A centrifugal high pressure pump (10B 58 SS) was obtained from Weber Industries, Inc., St. Louis, Mo. 63123). A leak detection system with sound alarm and automatic tap water shutdown was designed and built by one of the authors (M. M.)C3~. RESULTS AND DISCUSSION A d i a g r a m of the w a t e r p u r i f i c a t i o n s y s t e m is shown in F i g u r e 1. The s y s t e m is located in a maint e n a n c e a r e a remote from the l a b o r a t o r y , which e l i m i n a t e s pump noise exposure to the personnel. M u n i c i p a l d r i n k i n g w a t e r at 60 p o u n d s / s q u a r e inch (psi) serves as a feed s u p p l y for the system. The p r e f i l t e r (A) removes p a r t i c u l a t e m a t t e r f r o m the feed w a t e r which extends the life of the d i a l y s i s m e m b r a n e . A t a line p r e s s u r e of 60 psi, the r e v e r s e osmosis, (RO) u n i t (A) g e n e r a t e s dialyzed w a t e r a t a r a t e of 7 l/h, a booster pump increases the feed w a t e r p r e s s u r e to 200 psi, r e s u l t i n g in an i n c r e a s e d o u t p u t of 27 1/h. The dialyzed w a t e r is s t o r e d in a 150 gallon r e s e r v o i r (B). The q u a l i t y of this w a t e r is c o m p a r a b l e to t h a t of s i n g l y d i s t i l l e d water, according to the m a n u f a c t u r e r (5~. We have confirmed t h a t the specific r e s i s t a n c e is 0.025-0.5 megohms as s p e c i f i e d by the m a n u f a c t u r e r . A c i r c u l a t i n g pump (C) w i t h d r a w s the d i a l y z e d w a t e r f r o m the r e s e r v o i r into a closed c i r c u l a t i n g
A
¢
The reverse osmosis (RO) system (Milli-R040, I-Z R2000052), final water polishing unit (Super-Q ZD 00022S4), Reverse Osmosis Prefilters (CDPR-012-04), Ion Exchange Cartridges (CDMB-022-02), Super-C Carbon Cartridges (CEAC-022-02), and Millipore Membrane Filters (CFRA-022-05), were obtained from Millipore Presented in Part at the Twentieth Annual Meeting and Conference of the Canadian Society of Clinical Chemists, Ottawa, Canada, July 1976. *Inquiries to be directed to H. E. Sine.
Fig. 1 - - Schematic illustration of the water purification system. A) Reverse Osmosis Unit, B) Storage Reservoir, C) Circulating Pump, D) Flow Regulator, E) Charcoal/ Resin~Filter Polishing Unit, F) On Line Monitor, G) Water Taps.
BERTSCH, MARTINUS, ZIMBER, KUBASIK AND SINE
184
TABLE 1 SUMMARY OF THE COLLEGE OF AMERICAN PATHOLOGISTS REAGENT W A T E R SPECIFICATIONS
MINUMUM REQUIREMENTS
TYPE I
TYPE IT
TYPE n l
SPECIFIC RESISTANCE
(Megohms, Minimum) ....
i0
SILICATE
(rag/L, Maximum) . . . . . . .
HEAVY METALS
(mg/L, Maximum) . . . . . . .
0.5
0.2
0.01
0.01
0.01
0.01
0.01
0.01
COLOR RETENTION TIME OF PERMANGANATE
(Minutes, Minimum) . . . . .
60
SODIUM
(rag/L, Maximum) . . . . . . .
HARDNESS AMMONIA
(mg/L, Maximum) . . . . . . .
CULTURE COLONY COUNT
60
60
0.1
0.1
0.1
NEG
NEG
NEG
0.1
0.1
0.I
MINIMUM GROWTH
MINIMUM GROWTH
MINIMUM GROWTH
6.0-7.0
6.0-7.0
6.0-7.0
3
3
pH . . . . . . . . . . . . . . . . . . . . . CO2 (mg/L, Maximum) . . . . . . .
3
TABLE 2 SUMMARY OF THE NATIONAL COMMITTEE FOR LABORATORY STANDARDS PROPOSED REAGENT W A T E R SPECIFICATIONS
PARAMETER
TYPE I
TYPE II
10 4
105
MICROBIOLOGICAL CONTENT
(Colonies/l, Maximum) TOTAL BACTERIAL COUNT . . . . . . PARTICULATE MATTER,
microns (Maximum Size) . . . . .
1.0
1.0
PERMANGANATE TIME
(minutes, Minumum) at 25°C.. pH . . . . . . . . . . . . . . . . . . . . . . . . .
60 N.A.
10 5.5-7.5
RESISTIVITY,
(megohms-cm, 25°C) . . . . . . . . .
10
0.5
SILICATE,
(mg/l SiO~, Maximum) . . . . . . .
0.05
0.1
loop. A r e g u l a t i n g valve (D) maintains a pump outlet pressure of 40 psi. Subsequent to the regulator valve an unloader valve assures that in case of regulator failure, a pressure rupture will not occur by diverting water at a pressure greater than 50 psi from the circulating loop and r e t u r n i n g it to the reservoir. (Line pressure checks indicate a tolerance to 100 psi). Next the dialysis w a t e r enters the polishing unit (E) at 40 psi where it flows t h r o u g h a column of activated charcoal which absorbs organic macromolecules. The water then passes t h r o u g h two columns of mixed a n i o n / c a t i o n resins in a deionization process and is then t r a n s p o r t e d through a filter cartridge having a pore size of 0.22 microns which removes any bacteria and resin particles. The resultant water is of Type I quality ~4,~ at a line pressure of approximately 20 psi. The w a t e r now enters the main laboratory, where line pressure and resistivity are continuously monitored (F). The unit is located for easy accessibility by lab staff. In addition to continuous monitoring, a low resistivity valve ( ~ 1 5 megohms) activates a warning light. The water is made available to each work area
(14 locations) upon demand t h r o u g h polypropylene faucets connected in series (G). Resistivity measurements conducted at each of the f a u c e t locations indicate that no measurable water quality deterioration occurs. Unused water continues t h r o u g h the circulatory loop, re-entering at the circulating pump (between points C and D). The unused water again re-enters the polishing unit, assuring constant availability of Type I water. When water is drawn from the system, dialyzed water from the reservoir (B) replenishes the loss. A low water level sensing switch, located in the base of the reservoir disconnects the circulating pump if the water level drops below five gallons. This prevents pump burnout. The entire system requires minimal maintenance. Line pressure, resistivity, and water usage are observed and recorded daily. Replacement of all cartridges on the polishing unit is necessary upon the generation of about 6,500 liters of Type I water. The RO filter change is made when the tap water and RO pressure differential is 10 psi, about every 10-15 days. An average pass volume of tap water is about 2,500 liters per RO filter change. The RO dialysis membrane cartridge requires replacement when its output drops 3 1/h at feed water pressure of 60 psi. This occurs approximately every 12 months. The dialysis water reservoir requires occasional cleaning due to algae growth, primarily during the summer months. The water system is shut down, reservoir tank drained, and washed with household bleach. The reservoir is thoroughly rinsed with tap water and RO water prior to activation of the water system. The frequency of cleaning the reservoir is every 12 months. Current Type I water consumption averages about 270 liters per day. Operational costs which include cartridge replacement and yearly RO dialysis membrane change is $0.03 per liter. We have satisfactorily employed this system for nearly three years in our laboratory. ACKNOWLEDGEMENT We wish to thank Art Carafos for his assistance in the construction of the water system. R~FERENCES 1. Stier, A., Miller, L., and Smith, R., Reagent-Water, Specifications and Methods of Quality Control, College of American Pathologists, Commission on Laboratory Inspection and Accreditation. Skokie, Ill. (1976). 2. Reagent Water Specification and Test Methods for Water Used in the Clinical Laboratory. National Committee for Clinical Laboratory Standards, Villanova, Pa. (1976). 3. Martinus, M., Unpublished Results. 4. Weisbrat, I., Evaluation of the Milli-Q3/MillioQ2 Reagent Water System, Bulletin Millipore Corp., Bedford, Mass. (1974). 5. Knott, A., Investigation of a High Purity Water System, Atomic Adsorption Newsletter 14, 126 (1975).