Friday, March 21, 2008

Drugs in drinking water: How will this impact energy use?

A recent New York Times article brought attention to the presence of pharmaceuticals in drinking water. The article is actually based on an Associated Press article covering the topic in more detail. I recommend reading the full article, but here's a quick distillation:
  • Both over-the-counter and prescription drugs have been measured on the order of parts per million and parts per billion in many U.S. drinking water supplies.
  • How these drugs end up in drinking water: (1) you take medication, (2) your body uses some, but not all the drug, (3) what your body doesn't use is disposed of in your toilet, (4) wastewater (containing the drug) is treated and discharged into a surface water source, (5) downstream, surface water is collected, treated, and delivered to your tap as drinking water.
  • Standard water and wastewater treatment methods don't remove pharmaceuticals.
  • The EPA's water chief says, "We recognize it is a growing concern and we're taking it very seriously."

But what about bottled water? A report by Reader's Digest states that "more than 25% of bottled water comes from a public source," potentially having some of the same contaminants.

Is this really a big deal? Maybe. Maybe not. Usually human health-risk and cost-benefit analyses are done to decide what the maximum contaminant levels should be, if a contaminant is to be regulated by the EPA.

So how do we get drugs out of drinking water? Well, more advanced water (and wastewater) treatment requires more energy. Of course there's more research to be done in the area of advanced treatment, especially to remove pharmaceuticals. So far, reverse osmosis (RO) is one of the few technologies that remove pharmaceuticals, with two major drawbacks: (1) RO treatment requires specialized membranes and materials, high pressure pumps, and chemical addition, resulting in huge energy use, and (2) lots of waste, contaminant concentrated water is generated in the process. Researchers at The University of Texas are working on the latter issue.

Water doesn't get clean on it's own. As we require stricter standards for water and wastewater treatment in the U.S., we will need more energy. Do you favor adequate electricity supplies over clean drinking water? Hopefully we won't have to make that choice.

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