Joined: Wed Mar 02, 2005 11:32 am Posts: 4 Location: Lufkin,TEXAS
I just wanted to respond to the article in this months Dirt magazine written by Dr. Kellie Lancaster. First, I would like to point out that the Dr. is correct in the proposition that Chlorine is a very reactive molecule and in certain quantities and under certain conditions can be harmful. While there are other treatment technologies that are now available, they simply are too expensive for immediate implementation. The good Dr. is also correct in that it will take time for these technologies to make their way into water systems across the country. The EPA and TCEQ will make sure that these changes are implemented over time.
However, I think it is mis-information to think that chlorine usage will disappear completely within the realm of water treatment. Even though water can be treated using Ozone or Reverse Osmosis, these forms of treatment wonâ€™t provide residual disinfection after the water leaves the treatment plant. Part of Chlorineâ€™s job in water is to provide residual chlorine in the water mains underground after it leaves the treatment plant for future disinfection.
The use of Chlorine can be greatly reduced (and should be) in water treatment but it probably will never be eliminated. I would like to point out that we all have chlorine thank for the significant reduction in water borne diseases because of itâ€™s disinfection properties. It wasnâ€™t all that many years ago that water borne diseases, potable and non-potable, were the cause of serious widespread public health issues.
If/when a move is made to primarily non-chlorine based treatment at the plant, I expect they would continue to use a final pre-discharge dose of chloramine as an in-pipeline microbiostat until something "better" (i.e., cheaper and tolerable to the masses and governing bodies) comes along. I think the "normal" pre-discharge chloramine dosage acts more as a microbiostat than as a microbiocide, but I haven't tested city water's disinfectant capacity as it exits the tap. That might make a decent project for a school science fair, and it may be that compost tea developers already have explored that. One constraint on treatment options besides the usual disinfection and minimizing of carcinogenic disinfection by-products is the effect that treatment products have on mobilizing metals in the pipeline, especially in older water systems. It has been alleged that chloramine was responsible for the recent high measured lead levels in Washington D.C.'s water system. A further interesting question to me is how/whether chlorine-based disinfectants react/interact with the mix of prescription and otc drug residues in municipal water. Of course, a discussion of potable water treatment wouldn't be complete without mentioning the Chlorine Council's intense and entrenched lobby efforts on behalf of chlorine products.
_________________ In theory, theory and practice are the same; in practice, they aren't -- lament of the synthetic lifestyle.
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