Portable stack sampler measures stack gases and solids at low cost
letters
Water quality standards
DEARSIR: In your article “Approval of Standards Sets Pace for Protection of US. Water Quality” (ES&T, February 1969, page 120) there is an error in a table on page 121. The table implies that the nondegradation statement made by the District of Columbia was not acceptable to the Federal Government. In fact, the D. C. water quality standards, including nondegradation language, were fully approved by the Secretary of the Interior on January 17, 1969. I note, however, that your table had a January 20 cutoff date; this date is so close to January 17 that the reason for the error is understandable. Arnold Speiser Chief, Water Quality Control Division Department o f Public Health Government of the District of Columbia Washington, D . C. 20001
Industrial kidney process
Now you can easily-and at low cost-collect and measure solids, mists and gases directly from your stacks with Research Appliance’s new portable Staksamplr.TM Developed and used successfully by the National Center for Air Pollution Control, this new sampler provides isokinetic collectioR of pollutants from most chemical and combustion processes, With a trained two-man crew, it can provide three samples per eight-hour day.
Research Appliance Company Allison Park, Pennsylvania 15101 Area 4 12-96 1-0588
No. 57 on Readers’ Service Card 506 Environmental Science & Technology Circle
DEARSIR: The “Currents” item in the March 1969 issue of ENVIRONMENTAL SCIENCE & TECHNOLOGY (page 203) describing evaluation of reverse osmosis for treating dilute pulp and paper wastes incorrectly stated that the costs of this project last year amounted to $690,530. That figure covers the total cost for the entire grant which will extend through six field scale demonstrations on different wastes at different mills over a two-year period. Also included is another year of preliminary laboratory and pilot scale studies ahead of the design, construction, and operation of the 50,000- to 100,000-gallonper-day field unit. The field unit. mounted on an over-the-road trailer, was built under contract at a cost of $137,175 and there are two pilot scale units ( 1000-5000 gallons per day) used for three slix-month periods ahead
(Continued on page 508)
