There's no doubt that chlorine and chlorine gas can be effective. In fact, chlorine gas was utilized during World War I killing not only bacteria and viruses, but several hundreds of thousands of young men as well. Throughout Europe, families saw the effects of this deadly gas and did not desire to use it in everyday living. Instead, they worked to develop an environmentally safe and user-friendly form of water purification. A system that imitated "cleansing, refreshing" reactions in nature. The result: The development and application of ozone generators.

For years the standard solution for water purification in the United States has been chlorine or other chemicals. As early as the 1920's chlorine has been used in many public systems to disinfect drinking water. To this day, chlorine is used regularly to sanitize drinking water as well as swimming pool and spa water. The by-products of chlorine are not pleasing to the taste and can irritate our skin and eyes in pools and spas as well as in the shower or bath tub.

But the quick solution is not always the best solution. In fact, the application of chemicals for water purification and food treatment has been determined to be a misnomer contributing to health problems. For example, within the last ten years, studies have shown that chlorine can produce undesirable by-products - among them trihalomethanes. Trihalomethanes are carcinogenic.

Until many of the problems linked with chlorination were discovered, ozonation had been virtually unused for potable drinking water in the United States. Currently, there is a growing trend in the food and beverage industry to utilize ozone in product preservation and quality assurance. In Title 21 of the Code of Federal Regulations (CFR) ozone is affirmed as generally recognized as safe (GRAS) for use as an antimicrobial agent in the treatment of potable water for bottling. (It is the leading method of water treatment used by bottling plants). In addition, ozone is prior sanctioned under the Meat Inspection Act for use in meat aging coolers under a restriction that ozone-generating equipment is operated in a manner which will not result in more than .01 part per million (ppm) of ozone in the air and is shut off for definite periods as required for inspection of the meat coolers. Further, under EPA's jurisdiction, ozone is used to treat municipal water systems.¹

Ozone is often called "active oxygen". It is naturally produced in the Earth's upper atmosphere when sunlight passes through the air. For applications to water purification, ozone is most commonly produced by passing air past an ultraviolet light in a sealed chamber. The then ozone-rich air is discharged into the pool, spa or potable water through dispersion heads as it circulates through an existing filtration system. The first observations mentioning ozone's disinfecting property for drinking water date back to the end of the last century. In 1886, De Merites noted a reduction in levels of microorganisms after ozonation. A significant amount of research, both fundamental and applied, has since confirmed his initial findings. Among the most important works are those done by Katzelson in Israel, Sproul and Majumdar in the United States.

Ozone's destructive action on microorganisms in water is widely acknowledged, particularly on the Escherichi cold (E. coli), Cryptospondium, Poliovirus and Giardia cysts (including Giardia muris and Giardia lamblia). Ozone may be said to act blindly, since no limits to disaffection have been found in the numbers or species eliminated. Such universality may best be explained by the mode of action of ozone: in contrast to the usually employed halogens, ozone does not have a reversible inhibitor effect on intracellular enzymes. Because of its very high oxidation reduction potential, this disinfectant acts as an oxidant of the constituent elements of cell walls before penetrating inside microorganisms and oxidizing certain essential components (e.g., enzymes, proteins, etc.).²  When a large part of the membrane barrier is destroyed, the bacterial or protozoan cells lyse (unbind) resulting in gradual or immediate destruction. By attacking plasmodia, viruses, trophozoids, cysts, spores and/or cellular aggregates ozone can provide an effective barrier to the transmission of diseases given that the ozone is properly applied.³

In 1967, guidelines for ozone disinfection were established based on a series of studies done in 1964 and 1967 by Coin et al. Studies done on the Poliovirus determined that the following ozonation conditions always guaranteed at least 99.99% inactivation of Poliovirus and E. coli:

• Establishing a dissolved ozone residual level of 0.3 milligrams per liter.
• Maintaining the 0.3 mg/liter dissolved residual level for a minimum of 4 minutes.

For the above mentioned studies, 1 ml of virus suspension was added to 1 liter of water in a specially designed flask. A 5 mg dose of ozone was added to the flask and was inverted and shaken vigorously over the four minute period. Virus titration samples were obtained by diluting the total ozonated sample with a culture medium containing 10% veal serum (to destroy the excess ozone present). Additionally, these studies showed that each time the value of residual ozone measured in the water was below 0.3 mg/liter, viruses were only partially inactivated after the four or eight minute period of contact time with ozone. The antithesis being residual ozone values for higher than 0.3 mg/liter sufficiently inactivated the virus to below a limit of detect-ability in less than four minutes of exposure time.^7,8

Having established the necessary residual ozone concentration to provide 99.99% viral inactivation as 0.3 mg/liter in the batch studies, these investigators then set up a continuous flow column apparatus. In this apparatus, ozone was applied to virus-containing water samples on a continuous basis. The bubbles of ozone / air rose upward while the water flowed downward through the apparatus. Under these conditions, the ozone content of the water increased in gradual stages until it reached a theoretical maximum corresponding to a balance between the various demands of ozone (dissolving of ozone and release of ozone to the atmosphere, reaction of ozone with demand). Generalizing ozone disinfection was initiated and further experiments with other bacterial and viral germs reaffirmed these conditions were necessary and sufficient.⁹   Over a fifteen year period of research, ozonation conditions have shown that in normal operation water containing no suspended matter and little oxidizable matter is completely free of pathogenic bacteria after ozonation, according to the most accurate detection methods in use. Consequently, it is safe according to the most accurate detection methods in use. Consequently, it is safe to determine that maintaining a dissolved ozone residual of 0.4 mg/liter (0.1 mg higher than tested) for a minimum of 4 minutes is the rule for obtaining drinking water of high microbial quality.^1,10

Unfortunately, the Department of Health and Human Services currently limits ozonation processes to treatment by ozonated air-despite substantial documentation with regard to ozone's effectiveness for purification and elimination of bacteria and viruses in food products. Under Title 21 of the CPR the use of ozonated water in washing produce and food / meal products is not permitted. In order for a retailer or manufacturer to use ozone to wash or spray food products at the retail point of purchase, it is necessary to submit in accord with 21 CFR 171.1, a food additive petition. This petition must supply sufficient information to justify amendment of FDA's regulations to provide for the retailer/manufacturer's proposed use.²  The reasoning: a "safety concern" with the proposed use in the potential formation of ozone byproducts for which they felt safety data are lacking. How many years of research is needed for ozone to be recognized as a safe and viable alternative?  More than fifteen years of significant research verifying and reverifying consistency in data and effectiveness of ozone presently exists. Perhaps the problem is not effectiveness of ozone, but rather the hold that chemical companies have on governmental regulations - even to the point of denying a viable alternative exists that can effectively treat food products for deadly viruses (such as E. coli) and save lives.¹¹

At one time, there was an argument that ozone generators were expensive and not a viable method for many to use for purification. This is no longer true today.

1. Food and Drug Administration; HHS, U.S. Pharmacopeial Convention, Inc.; Rockville MD, P.481 Section 184.1563 Ozone.
2. Handbook of Ozone Technology and Applications,; Vo/. 11. Ozone for Drinking Water Treatment; Rip G. Rice and Aharan Netzer, Butterworth Publishers, MA; 1984; p.1.
3. Handbook of Ozone Technology and Applications,; Vo/. 11. Ozone for Drinking Water Treatment; Rip G. Rice and Aharan Netzer, Butterworth Publishers, MA; 1984; p.2.
4. Schwiz. Heits. Hydrologie; F. B. Sulzer, B. Ramadan and K Wuhmmann.; 1959 2: pg. 112-121.
5. Water and Wastewater Disinfection With Ozone; Crit. Rev. Environ Control; RN. Kinman; 1975; Volume 5, Illue l; pp. 141-152.
6. "La Destruction des Bacteries et Virus par l'Ozone." Eau Quebec; A.J. Drapeau and G. Paquin; 1977; Volu 14, Issue 4 pp. 95-101.
7. Inactivation par l'Ozone due Virus de la Poliomyelite dans les Euax; la Presse Med; L. Coin, C. Hannoun and C. Gomella; 1964; pp. 2153-2156.
8. Inactivation par l'Ozone due Vws de la Poliomyelite dans les Euax; la Presse Med; L. Coin, C. Hannoun, C. Gomella and J.C. Trimoreau; 1967; pp. 1883-1884.
9. Rapid Test for Assay of Ozone Sensibvity in Escherichia coli; Mo. Gen Genet; C. Hamelin and Y.S. Chung; 1976; vol. 145, pp. 191-195.
10. Modalites de l'Action Desinfectante de l'Ozone; Wasser Berlin '77; j. Chedal; Berlin, FRG: Colloquium Verlag Otto H. Hess: 1978: DD. 106-112.

Additional References

Memphis Germ Killing Process To Get A Test Run; Shepard and Scott; Memphis Business Journal; 1993; Vol 14, Issue 40, Section 1, pg. 8.

...Dr. Hampson; Cal Poly State University; Professor of Food Science; San Luis Obispo, CA - coloform testing.

Ozone in Water Treatment Application and Engineering; Lewis Publisher; Chelsea Ml 1991

By Paulette Scoville