Small amounts of silver are incorporated in mixture of ion exchange resins, and water passing through this mixture is thus exposed to silver ion concentration. System is useful in self-contained water systems except city water systems where residual chlorine level is stipulated

Parry, E. P.

English

NASA Technical Reports Server

August 1971	 Brief 7l-10278 
NASA TECH BRIEF 
Manned Spacecraft Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a aubscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
A Silver Ion Water Sterilization System 
A novel method of sterilizing water has been de-

veloped. Small amounts of silver are incorporated in a 
mixture of ion exchange resins and water passing through
this mixture is thus exposed to a concentration of silver
ions. Silver ions are a well-known bactericide, but silver 
salts have not previously been seriously considered as a

substitute for sodium hypochiorite because of their
corrosive and toxic qualities. In this new method, how-

ever, the deleterious effects attributable to silver ions 
have been contained. The system will therefore be useful 
in self-contained water systems such as those in air-

craft and trailer vehicles, and to campers. However, this
method of sterilization may not be applied to city water
systems, for which a residual chlorine level is stipulated. 
Considerable effort has been devoted to the de-

velopment and study of techniques for sterilizing the
drinking water supply carried aboard Apollo spacecraft.
The most common sterilant is sodium hypochlorite, and

silver ions have not been seriously considered as an al-

ternative until recently. Concern about the corrosive
potential of silver salts and anxiety over their toxicity 
have been the main reasons for this. But silver ions are
known to be an effective bactericide and, if these haz-

ards are overcome the concept of using silver ions has 
some distinct advantages: small sterilizing units, easy to

construct, needing no power or attention in use. 
In the NASA sterilizer, water flows through a high 
concentration of silver ions contained in a cation ex-

change resin. If bacteria are present, their exposure to
the silver ions results in bacteriological action leading to 
the killing of the bacteria. In practice a mixture of three 
resins, compounded in the form of a cartridge, has 
proved to be the most efficient cation exchange resin 
for the impregnation of the silver ions. The technique 
was tested in the Apollo water system under simulated 
operating conditions with known quantities and types of 
bacteria. The results showed that the contaminating or-
ganisms were effectively sterilized. 
This innovation will be of interest to manufac-
turers of self-contained drinking water supply systems - 
such as those used in aircraft and vehicles. It will also 
find a use in individual applications such as refineries. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Manned Spacecraft Center, Code JM7 
Houston, Texas 77058 
Reference: TSP71- 10278 
Patent status: 
No patent action is contemplated by NASA. 
Source: Edward P. Parry
North American Rockwell Corp. 
under contract to
Manned Spacecraft Center
(MSC-15734) 
Category 04 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Govcrnmnt assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000277 2020-03-17T02:20:48+00:00Z


A silver ion water sterilization system

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