EPA evaluated !* - ---- .-q&/---- \ " I
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total organic carbon volatile organic carbon total carbon Dohrmann's DC-50 organic analyzer makes 811 of these measurements accurately and rapidly. Based on proven methods, it avoids interferences and undesirable pyrolysis reactions that historically have resulted in significant errors. Here's why the DC-50 is the complete solution for the analysis of carbon in water: D I R E C T READOUT. Four-digit presentation shows carbon content directly in mg/liter or ppm. N o recorder needed! D I R E C T MEASUREMENT. A single sample injection gives either Organic Carbon or Total Carbon content directly, n o t
by difference. INDEPENDENT MEASUREMENT. Volatile Organics are determined separately from Total Organics to aid in source identification. RELIABLE MEASUREMENTS. Determines important, lightweight volatiles such as low molecular weight alcohols and ketones, normally lost by acidification and sparging. FAST: 5 minutes per determination ACCURATE: repeatability of f 1 mg/ liter or f 2% W I D E R A N G E : 1 to 2,000 mg/liter (ppm) without dilution P R I C E : $7,500, including start-up assistance and operator training
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ENVIROTECH
Circle No. 22 on Readers' Service Card
1082
LETTERS
Environmental Science & Technolog
Automotive emissions-correction Dear Sir: I was pleased to see the article on the stratified-charge engines (ES&T, August 1973, p 688). There were two small communication errors in the middle column of page 689 where test results on the Texaco Controlled Combustion System powered army vehicle were discussed. These occurred in the last sentence of the first full paragraph. This should have read, "After 50,000 miles, under level road, 40-mph conditions, the numbers were 1.31 g/mile C O , 0.34 g/mile HC, and 0.37 g/mile NOx." Unfortunately, the level of NOx emissions through a communication error is changed from one that passes the 1976 standard then in regulation to a level that does not pass. This standard, you will recall, is 0.4 g/mile for NOx. William T. Tierney Texaco inc. Beacon, N . Y . Air pollution measurements Dear Sir: The article, "Project Threshold Verifies Tests," ( E S & T , April 1973, p 303) highlights the problem a journal such as yours has in reporting complex technical information before the experimental details and data analysis supporting the claims made by the investigators are available for review by the scientific community. Validation of air pollution measurement methods by the interlaboratory collaborative testing route, as is being done in Project Threshold, is in its infancy, and the manner in which the many complex problems of system design, conduct of experiments, and analysis of data are dealt with must be evaluated very critically before sound conclusions can be reached. Unfortunately, full reports on the validation tests carried out in Phase I of Project Threshold are not generally available, and, for this reason, claims made for the methods are still in question. Through the kindness of Walter Cropper, project manager for Threshold, we have had the opportunity to review preliminary draft reports on the validation tests for measuring nitrogen dioxide by ASTM method D1607 and sulfur dioxide by ASTM method D-2914 and have been given the opportunity to comment on these test results. While we are in general agreement that the methods are reliable means for measuring NO2 and SO2 in the atmosphere, we have res-
ervations about the precision and accuracy claims made for them and feel that further review of the test results for these methods is still required before such definitive statements are justified. We have not reviewed reports on ASTM methods D-2010 (sulfation rate), D-1739 (particulate matter-dustfall), D-1704 (particulate matter-tape samples), and D-3112 (lead). Notwithstanding our concern about premature claims, we are strongly in favor of having air pollution measurement methods validated and have had a substantial program in progress for several years to standardize such methods. Our emphasis, unlike Project Threshold, has been the standardization of methods of measurement required to determine compliance with national regulatory standards. John B. Clernents
National Environmental Research Center Research Triangle Park, N.C. 2771 1 Nitrogen removal Dear Sir: I read with interest the informative feature article by C. E. Adams, Jr., on removing nitrogen from waste water ( € S A T , August 1973, pp 696-701). Several processes are reviewed in detail but processes involving oxidation of ammonia with chlorine are only briefly mentioned. Because of their potential usefulness they should have been covered in more detail. A previous article (T. A. Pressley et al., €S&T, July 1972, pp 622-8) examined the use of breakpoint chlorination for removing ammonia from waste water. I t should be noted that this process can be used as the sole ammonia removal process or it can be used to remove residual ammonia from the effluent of a single stage, nitrifying activated sludge system. In either case, there is a secondary advantage in that disinfection is also achieved. A major disadvantage is that partial ammonia removal, which in many cases is all that may be required to meet the criterion which has been set for the receiving stream, is difficult to achieve efficiently. A modifica,tion of the breakpoint chlorination process is possible if only partial ammonia removal is desired. Addition of chlorine at less than breakpoint dosages along with pH adjustment so that dichloramine is the principal product of chlorination is an important aspect of this
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Celesco. process. Subsequent contact of dichloramine with activated carbon results in its conversion to nitrogen gas and hydrogen and chloride ions. Chlorine residuals can be completely eliminated from the effluent by the carbon as well, and thus problems resulting from chlorine residual toxicity in receiving waters can be avoided. This process was tested in a pilot plant at Owosso, Mich. (P,A. Atkins et al., Proc. 27th Ind. Waste Conf., Purdue Univ.. 1972, in press) and the basic reactions were studied in more detail by others (R. C. Bauer and V. L. Snoeyink, J. Wafer Pollut. Conir. Fed., in press). There are still many valid questions concerning this process, but it does appear to have enough promise to warrant its inclusion in a discussion of alternative processes. Vernon L. Snoeyink University of illinois at Urbana-Champaign ’ Urbana, ill. 61801
New Washington ediforiai staffers
Gibney and Josephson join ES&T Both Lena Gibney and Julian Josephson joined the publication in October. Mrs. Gibney has degrees from Wilmington College and the University of Michigan pius industrial experience at Shell Development Co., Shell Chemical Co., and TracorJitco, Inc. Mr. Josephson has degrees from New York University, the University of Paris, and graduate studies at Catholic University plus experience with the U.S. Naval Oceanographic Office, teaching experience with School of Marine and Environmental Technology of the Florida institute of Technology, and business experience with General Enterprises Corp. Each will soon be contributing to the Outlook section of ES&T.
The only SO, monitor actually using the National Bureau of Standards fluorescence technique. Since the NBS revolutionized SO2 monitoring with the gas fluorescence technique, some manufacturers have slapped a “fluorescent” nameplate on their products. They’d like you to think their instruments use the NBS method. The truth is that only Celesco builds a gas fluorescence monitor under NBS license.While others are frantically playing follow-the-leader, Celesco can offer you all these benefits right now... Celesco Model 5000 detects SO, and only SO, in source emissions. It gives accurate, instantaneous readings from 0-5000 ppm continuously-even around the clock-without chemical reagents. You can recalibrate the entire system, as often as you want, merely by turning a knob. No shut-downs, no interruption to sample flow. And you never have to use bottled calibrating gas or permeation tubes. The self-contained Model 5000 weighs just 22 pounds. Low 40 watt power consumption makes it ideal for field use. Write us today for free descriptive literature and performance specifications. Celesco Industries Inc., Environmental and Industrial Products Division, 3333 Harbor Blvd., Costa Mesa, CA 92626. 7141 x n Equal Omatunny Emplqw-MIF
Celesco makes things simple. Circle No. 26
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Readers’ Service Card
Volume 7, Number 13, December 1973 1083
