what is the purpose of injecting ozone into water in the purification process?
The same purpose as introducing chlorine: It kills off germs. Ozone is typically used in Europe, while chlorine is typically used in the U.S. The main difference is that ozone doesn’t stay effective for as long-- it decays into ordinary oxygen. This is both an advantage and a disadvantage: On the plus side, it means that you’re not drinking any poisons with your tapwater, but on the minus side, it leaves the water vulnerable to any germs that might later enter the water system.
Chronos sumemd it up very well. Some other good things about ozone (O3) are its relative safety and its incredible disenfecting power.
It is something like 10 - 20 times more effective than chlorine for a given dosage and contact time (the duration the O3 is in contact with the water). Yet, it dissipates rapidly and leaves water susceptable to subsequent contamination in a community distribution system. All distribution systems leak to some degree, spilling water and letting contaminants in.
Also, O3 is typically manufactured as needed on-site, using just electricity and air, eliminating safety problems with transporting, handling and storing large quantities of liquid chlorine.
Chlorine is so common mainly because it is effective, cheap, and most water treatment plants were built long before O3 came into use.
Another benefit of ozone is that removes tastes and odors present in the water before treatment. The benefit of chlorine that Chronos mentioned (that it continues to protect against bacteria in the pipes) is lost in Europe anyway. They are so concerned about the bad taste of chlorine that in the rare instance when they do use it, they are careful to remove the chlorine before sending it through the pipes. The figures I have (very old) indicate that ozonation is several times more expensive than chlorination, but still we’re talking only a fraction of a penny for either method.
related thread: http://boards.straightdope.com/sdmb/showthread.php?threadid=26277
Water in its pure form is probubly tasteless. I would not know as I have never had the privilage of such water. Most of the water we drink has trace elements of minerals giving it taste. Calcium makes it sweeter, Magnesium gives it more of an edge (if memory serves,) and Lithium makes it happier (albeit 10 pounds heavier). I propose ozoning, adding half the chlorine normaly added, the proper minerals, and so on, then bottling the water, giving it a distinct, unique taste that will not only help your bones but will make you less inclined to suicide. On my part, I must confess, this is just a thought. I also want to know if I should add this to my profile, and if so should I modify it in any way shape or form.
“The very concept of me being mentaly sane is both new and novel to me.”
Ozonation also generates fewer harmful chemical by-products than chlorination does. Some of the newer water treatment facilities are using ozone (especially if they have a big budget and a mid-sized distribution system).
The vast majority of bottled water is ozonated right before the bottles are sealed, which gived the bottles a longer shelf life (drinking water goes stale.) This isn’t new, and has been shown to be safe and effective for at least 30 years. The water tastes much better than other (chemical) disinfecting techniques.
Many above ground electric spas are equiped with UV ozone generators that allow you to greatly reduce the amount of chlorine you would use without it, and if you add a teaspoon or so of Hydrogen Peroxide every once in a while it really kicks up the effectiveness. The small amount of Chlorine is still needed to keep the water in isolated puddles from going green or from excessive growth occuring when the system is off.
Many athletic facilities and hotels are putting ozone treatment systems in their pools to accomodate European atheletes and visitors who find high chlorine levels bothersome. The Olympic committee required ozone in any pools where competition was occuring. I have to admit after trying both that the ozonated water is much nicer, especially in a spa where you breathe in a lot of steam, and the chlorine seems to get into your lungs. Nasty stuff, although you can be comforted knowing the phlem you are coughing up is probably mostly sterile.