Correction: In the July issue, author Mel Mirliss’ article—“A Comparison of DE and Crossflow Filtration: Just the Facts, Ma’am”—contained a reference to a Figure 2 on page 50 that should have referred to Figure 3, which was missing. In essence, the author wanted to convey that “a typical DE filtration system can be installed for about one-half the capital cost of a membrane filtration unit.” The correct figure is to the right.
Time for my monthly complaint
I read the Bruce Eccleston article today (“UV: Is the Water You’re Drinking Safe?” WC&P, July 2002, pp. 72). The references to the tables and figures are a bit mixed up, but my concern is primarily about Table 1. This supposedly indicates UV dose for various microorganisms. The table, however, fails to indicate the degree (log) of inactivation that would be achieved at these levels, and the units of dose are not given. Looking them over, it is obvious that microwatt seconds per square centimeter (µWsec/cm2) was the intended unit. But, the text states that dose is generally presented as millijoules per square centimeter (mJ/cm2) or milliwatt seconds per square centimeter (mWsec/cm2). As a result, a reader likely would interpret Table 1 as indicating thousands of mJ/cm2 are necessary. Also, in an article supposedly about drinking water safety, the inclusion of nematode eggs and paramecium under “Protozoa,” with no mention of Giardia and Cryptosporidium, is questionable. Under viruses, what is bacteriophage (E. coli)? E. coli is a bacterium, and in fact is properly listed under bacteria. Likely, what was meant was MS2 bacteriophage.
Clancy Environmental Labs
St. Albans, Vt.
Our apologies for allowing the omissions and misnomers to pass through unchecked. We’ll correct this for the online version of the article.—The Editors
Strong-arming the postal service
I just wanted to drop you a note to say “good for you!” on your decision to stop using bind-in cards for reader service (Viewpoint, “Reader Service, Breaking News, Misguided Media—and Aqua Europa, Again,” July 2002, p. 6). I’m in favor of any plans to give the post office less money! We also have been wrestling with the “circle card” problem for awhile now in our two magazines, Water Well Journal and Ground Water Monitoring & Remediation. It’s an expensive program that readers are using less and less with the advent of easily accessible company websites. Currently, I’m looking at some web-based solutions. Perhaps we will follow your lead and move to a fax only reader service program—and cut the post office entirely out of the loop!
Jill Ross, Director of Publications
National Ground Water Association