Wednesday, July 12, 2006

A Treatment Plant's Ultraviolet Disinfection System Breaks Down and Westport Beaches Are Closed As A Result

Sewage treatment plants are switching to ultraviolet disinfection of wastewater instead of chlorination because it’s safer. Chlorine is a poison that poses a threat to the workers at the sewage plants and, in residual amounts after it is discharged in wastewater, to organisms in Long Island Sound and its tributaries.

But just as chlorination systems sometime break down, so do ultraviolet disinfection systems. Health officials closed Sherwood Island State Park and Compo Beach in Westport yesterday after a malfunction at a treatment plant on the Saugatuck River.

The area is one of the richest in the Sound for shellfish, which this Stamford Advocate story mentions only in passing. If the beaches were closed, I assume shellfish beds were too.


Anonymous Bryan Brown said...

Our local STP in Glen Cove recently installed a UV system to replace the chlorine-based system, but your post begs the question: what are the contingencies in the event of a UV malfunction? The back-up generator they have addresses power failures, but what about a "computer software glitch"? In the interest of removing any potential hazards from the storage of sodium hypochlorite, perhaps they've cut it too close. It's something we'll be looking into.

The timing of the tests results for the beaches mentioned in the article is curious. If it takes 24h to get a result, how did they test Sherwood Island so quickly? The timing for Compo Beach sounds about right.

Finally, your comment re: the shellfish beds brings up another issue. USEPA now requires testing for enterococci at marine beaches, instead of fecal coliforms. According to USEPA, their studies show it's a better indicator for disease-causing organisms, at least in marine environments. What I can't understand is that water quality monitoring for shellfish beds is still based on fecal coliform, as is the monitoring done by STPs discharging to marine environments (as I understand it). Shellfishing is the highest form of use a waterbody can have (higher than recreational uses), yet it doesn't merit the so-called gold standard for bacteria monitoring. It seems like an inconsistent approach to WQ monitoring.

1:22 PM  

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