LETTERS Sulfur gas cleanup Dear Sir: With regard to the news item carried under Currents (€SAT, July 1974, p 599), I would like to clarify the status of IFP technology for cleaning up sulfur-containing gases. Actually there are two different IFP cleanup processes, one for Claus unit tail gas and one for stack gas from power-generating and similar large installations. Both are liquid phase processes in which SO2 and H2S form a complex with a proprietary cataly$t dissolved in a polyethylene glycol solvent. There are important differences beyond the basic chemistry, however, but this is not the place to go into detail. What I would like to set straight for the record, though, is the fact that both IFP processes are far past any development stage. Twenty-two Claus tail gas cleanup plants have been licensed by IFP in the U.S., Canada, Europe, and Japan, of which 14 are already operating. Four stack gas cleanup plants have likewise been licensed. One in Japan started up last month and a second in France is scheduled for Startup in September. Pierre Bonnifay institilt Francais du Petrole NewYork. N.Y. 10022
However, there are many examples where metal salts work satisfactorily without the aid of polyelectrolytes. Incidentally, the list of billion dollar companies should have included Allied Chemical. Allied is the largest producer of aluminum sulfate but does not produce ferric chloride. M. 0 . Ericson Allied Chemical Corp. Morristown. N.J. 07960
More on Four Corners Dear Sir: Our staff has reviewed, with interest, the recent article on the scrubber system installed at the Four Corners Power Plant (ES&T, June 1974, p 516). The article was factual and well written: but, in my opinion, reflects a lack of understanding of the problems facing state regulatory agencies, particularly those in undeveloped and lightly industrialized states such as New Mexico. I do not see that the problems of "moving targets" and available technology are behind us. This statement may come as a surprise to those who believe the federal new source performance standards define the limits of technology, that the federal ambient air standards provide the .criteria for control design, and that the environmental movement died giving birth to the energy crisis. Gravel beds: Who was first? New Source Performance StanDear Sir: We agree with all the dards (NSPS) suffer from the flaw of statements made in. the PAT report being irretrievably tied to a compro(ES&T, July 1974, p 600) except one mise definition of available technolowhich is quite misleading. gy. While this may be necessary on a The first gravel bed filter on this national basis to prevent large-scale continent went in operation early in economic and societal dislocations, 1972 in our plant here in Mississauit has obviously resulted in nationally ga. I t was supplied by Lurgi and required controls for new sources Gesellschaft fur Entstaubungsanlawhich are less restrictive than the degree of control currently being gen (GfE, Munich, Germany) for dedusting the exhaust air on a clinker achieved by existing sources. For excooler of a 3000-ton-per-day cement ample, the NSPS for particulate kiln. emissions from coal-fired generating stations is 0.1 Ib per MBtu'S and yet C. Zuiaut. V-P Operations there are four large coal-fired boilers St. Lawrence Cement Co. in New Mexico which are presently Mississauga. Ont.. Canada emitting less than half that amount. Because of the environmental necesAll about chemicals sity, many western states will be requiring new sources to control to a Dear Sir: We found Mr. Gross's level better than is required by article, "Markets for Chemicals Grow NSPS-certainly this is currently the and Grow," (ES&T, May 1974,' p situation in New Mexico. 414) very interesting, and we concur The overwhelming reason why I with many of his observations. We believe ambient air standards do not were surprised, however, that his provide adequate design criteria, projections appeared not to include however, is one to which our society the use of precipitant/coagulants in has traditionally been responsive and existing wastewater treatment plants that is economics. It has not been for phosphorus removal and imgenerally recognized that one of the proved reduction in BOD and suspended solids. Also, polyelectrolytes effects of recent federal and state legislation is that before a Construcare used where needed as Coagulant tion permit can be obtained for a aids with both alum and ferric salts. 962
Environmental Science &Technology
new source the permitting agency must first determine that neither state nor federal standards or regulations will be exceeded. Should regulatory agencies adopt emission regulations for existing sources that allow emissions of such magnitude that resulting ambient concentrations are at or near the level of ambient standards, they will have created a zone inside which no new industry emitting the same pollutant can be located. The principle of no significant deterioration if it continues as a legal requirement will act as a further limitation. In review, there are strong economic as well as environmental pressures in New Mexico and, I believe, in other western states for the best possible air pollution controls. These pressures are operating presently to require better pollution control than is required under the Clean Air Act, and in my opinion will continue to operate into the future. Unless industry both new and existing recognizes this situation the problem of moving targets will continue to haunt us. The additional problem for industry of having to wrestle with technology that is newer and better than that which can be obtained "off the shelf" is also a way of life in much of the West. It seems appropriate for a publication such as ES&T to be aware of these factors when discussing the problems of air pollution control in New Mexico or other western states, and to include these considerations so as to provide proper balance. Cubia L. Clayton, Chief State of New Mexico Environmental I mprovement Agency Santa Fe. N.M. 87501
Ember joins ES&T Lois R . Ember joined the publication in September 1974. Mrs. Ember has degrees from the University of IIlinois (BS in zoology) and the University of Chicago (MS in physiology) and several years of experience at Meloy Laboratorles (Springfield, Va.) and Commonwealth Services, Inc. (Washington, D.C.). She will be contributing to the staff-written portions of ES&Tand coordinating features.
