Tackling T&O in Zebra Mussel‐Infested Waters

Abstract

This article describes a situation at Hemlock Lake, the drinking water source for the city of Rochester, New York, where a taste and odor (T&O) problem occurred in the summer of 2004. In 2004, two unusual environmental conditions at Hemlock Lake were identified as possible causes of an unprecedented T&O event. The first was record spring and summer precipitation produced unusually heavy runoff in the months leading up to and during the event. The second was that 2004 was the first year the lake had become heavily populated with zebra mussels. The article presents three treatment options that were considered that include: treat the source water; destroy T&O compounds using oxidation; and, adsorption by activated carbon. Granular activated carbon (GAC) was selected as the treatment solution, and the article discusses the suitability of GAC for this particular situation and the conversion process at the Hemlock Lake treatment plant. The recurrence of the T&O problem in 2005 and 2006 tends to indicate that this problem is associated with the exploding population of zebra mussels.