Cleanup: that old black magic works again! A
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For years, activated carbon has been used to make water taste better, and to kill air and water odors. Now, it may be used to remove aqueous organic pollutants. Its markets will be greatly expanded, once certain EPA water regulations are promulgated, perhaps early next year _ _
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From far away, it looks nondescript-a mass of black granules or powder. But looked at under a microscope, it can be seen to have many different, elaborate structures. “It” is activated carbon, which can be granular (GAC) or powdered (PAC). Sources of activated carbon could be bituminous coal, anthracite, lignite, wood, or coconut shells. The raw material and mode of manufacture of the activated carbon are the principal factors for determining its structure, adsorption capabilities, and regenerability. These features, in turn, are what decide what the carbon’s application will be-for example, potable or drinking water treatment (dwt), wastewater treatment (wwt), decolorization, solvent recovery, or odor control.
Irwin H. Suffet and Michael J. McCuire
Certain recent developments have caused the attention of the water treatment industry to be focused on the use of activated carbon for trace organics removal. A principal one was the publication of the proposed organics regulation (Federal Register, 43 FR 5756). This proposal to reduce the exposure of consumers to trace organic compounds in drinking water evolved from the announcement in 1974 that there were potentially carcinogenic organic compounds in New Orleans’ drinking water. As a result of two subsequent nationwide surveys of trace organics, the U S . EPA concluded that sufficient information existed to regulate organic chemicals in drinking water. A major section of the proposed organics regulation requires the application of granular activated carbon (GAC) treatment to vulnerable water supplies. 1138
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Environmental Science & Technology
Irwin H. Suffet Drexel Unicersity Encironmental Studies Institute Philadelphia, Pa. 19104
Michael J. McCuire Brown & Caldwell, Consulting Engineers Pasadena, Cal$ 91 109
Julian Josephson Lois R. Ember ES& T Washington, D.C. 20036
However, the decision to hold a symposium on activated carbon adsorption occurred during the course of a research project funded by the Philadelphia Water Department, and before the proposed regulation was announced. As the symposium was being organized, it became apparent to the symposium organizers that the available information on G A C removal of trace organics was seriously fragmented among several different disciplines. Indeed, in several cases, it was reported only in European research journals. The original purpose of the September symposium at Miami Beach was to compile the most up-to-date literature available into one source, so that the data would be available to all interested parties. The idea of bringing experts, involved in many disciplines, together from seven countries was an attempt to accelerate the coordination of the available understanding of G A C treatment. As it became apparent that GAC treatment was to be an important part of proposed drinking water regulations, assistance was sought from the EPA and the American Water Works Association (AWWA) to expand the scope of the symposium. A principal aim would be to reach the water utilities, and to help them with the future task of implementing the organics regulations. Cosponsorship by the AWWA and support from the EPA’s Office of Drinking Water greatly aided the symposium’s ability to reach the potentially impacted audience. Of importance is the fact that the symposium provided 0013-936X/78/0912-1138$01.00/0 @ 1978 American Chemical Society
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GAC pore structure. From a coconltr shell b a s e . . . a coal base
“cross-fertilization” of theoretical understanding and practical case-histories of G A C pilot-scale treatment, as well as actual efforts to design full-scale G A C treatment systems. Thus a major effort was made to give the engineers and scientists opportunities to interact. For that reason, after each half-day session, nine panel discussions were held to amplify the formal papers. Questions that addressed areas of mutual interest or disagreement were posed to panels composed of the session speakers. Arrangements have been made with Ann Arbor Science Publishers, Inc. (Ann Arbor, Mich) to publish a series of books that will consist of the symposium papers. The papers will be arranged by theme. The books will also include pertinent transcriptions of the panel discussions that amplify the papers.
Adsorption models Early attempts to arrive at a comprehensive description of the G A C adsorption mechanism were directed toward attempts to correlate solute variables with adsorption efficiencies. Examples of the single variables that have been correlated to measures of adsorption capacity include molecular weight, aqueous solubility, molecular size and functionality. In recent years, serious attempts have been made to develop a comprehensive model that will explain the adsorption process. For example, models discussed at the symposium, some of which are listed in Table 1, range from numeric- and analytical-solution mathematical models (MADAM, Multi-Component Isotherm) to detailed investigations of the thermodynamic properties of the solvents, adsorbents and adsorbates (Ideal Adsorption Solution theory, Polanyi theory, Solvophohic theory, Net Adsorption Energy concept). These models serve different purposes, do not need the same types of data input, and are not developed from similar
and a wood hase ( / f o r )
theoretical bases. They were developed by investigators in different fields of interest; the symposium was the first opportunity for the models to he presented together, and discussed in a critical manner. Similarities between several of the thermodynamically-based models were noted. The possibility of incorporating the thermodynamically-based models into the mathematical models was recognized.
New techniques helped Data needs for the models are one reason for the study of the adsorption characteristics of pure compounds and mixtures of compounds. Theoretical studies on the adsorption mechanism have been done for decades, and it is well-known that some of these early studies are still useful guidelines and sources of basic data. But the availability of gas and liquid chromatography has greatly enhanced the ability of investigators to branch out from monitoring a group of organics that can be easily analyzed by spectrophotometric methods to checking out an almost unlimited variety of organic compounds-a previously difficult or impossible task. Laboratory studies on ideal systems are the first of a series of steps that lead through hypothesis development, pilot-scale experimental design, operation of pilot column adsorbers, design of full-scale G A C columns, and construction/operation of G A C adsorption systems. Unfortunately, there are many unknown data needs along this path and, at this point in the method development, it is not possible to make dramatic jumps over several steps. Three comprehensive levels of investigation are needed to resolve these unknowns concerning full-scale G A C system implementation. These levels are laboratory, pilot scale, and full scale. A few of the many studies that were reported at the symposium, which investigated the adsorption characteristics of pure compounds and mixtures of compounds, are listed in Table 2. The list of synthetic organic
TABLE 1
Adsorption models Model
MADAM
Polanyi Adsorption Potential Theory
Net Adsorption Energy Concept
Description
A numeric solution model discussed by Walter J. Weber, which can accommodate aspects of fluid dispersion, solids mixing, multi-solute interactions, and biological growth. Breakthrough curves from isotherm and kinetics data are predicted. Reviewed by Milton Manes, with regard to its applicability to the adsorption of organic liquids and solids over a wide concentration range, and organic acids as a function of pH. A calibration isotherm on a particular carbon can be used to predict the isotherms for a wide range of other solutes. The results from pilot column studies can also be interpreted through use of this con-
cept. Developed from first principles associated with theory for adsorption chromatography by Michael J. McGuire and Irwin H. Suffet. A calculation method was developed, which determined net adsorption energies for organic compounds in a waterlsolutelactivated carbon system. Calculated data used for isotherm evaluations and prediction of breakthrough in column studies. Volume 12, Number 10, October 1978
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TABLE 2
Adsorption of pure compounds and mixtures Organlc compounds
Study models
Study descriptlons
Phenol; pnitrophenol; methylene blue; rhodamine 6; oxalic, succinic and adipic acids; stearic acid from benzene and carbon tetrachloride; phenolbenzene mixtures; ethylene glycol Chloroform, dichlorobromomethane, bromoform, humic
Wide variety of isotherm models
B.R. Puri discussed the importance of the carbon surface chemistry in the adsorption of many organic compounds.
Freundlich isotherm
Chloroform, benzene, background TOC
High pressure mini-column technique (HPMC)
M. Youssefi presented basic adsorption data, using isotherm and breakthrough curves for single compounds and mixtures. M.R. Rosene discussed the HPMC technique as a tool to compare carbons, and demonstratethe competitive effect of background TOC on compound breakthrough curves at the ppb level.
chemicals illustrates the increasing concern with the need to remove those that come from industrial contamination. Isotherms, kinetic studies, and breakthrough curves from small columns were the investigative techniques of choice for the studies. The breakthrough curve approach received a boost when a new High Pressure Mini-Column (HPMC) techniqde was introduced. This produces breakthrough curves in a short period of time, models the competitive effect of background T O C on compound breakthrough curves, and facilitates comparisons between brands of carbon.
Pilot studies: sophisticated analytical methods are the name of the game As models of the full-scale system, pilot columns are indispensible parts of the design process. For instance, in a matter of weeks, a properly designed pilot column investigation can study 10 or more parallel column tests. Such tests can compare brands of activated carbon, evaluate the effect of increased contact time in the carbon beds, ascertain the feasibility of resin adsorbents with in situ steam regeneration, or determine the effect of pretreatment on organic chemical removal. Among other advantages of the pilot-scale study for GAC design is the opportunity to sample large influent and effluent volumes of the water to be treated, and determine
the treatability of the specific organics of concern. Isolation methods, such as the purge-and-trap technique, liquidliquid extraction, and macroreticular resin adsorption can be followed by qualitative gas chromatography/mass spectrometry (GC/MS) identification and quantification. In some cases, the organic profiles that are generated by glass capillary G C can be used in pattern-recognition analyses to determine significant organics removal. Irwin Suffet discussed important aspects of monitoring the efficiencies' of activated carbon columns in removing organic compounds. He pointed out the difficulty in relating the removal of specific organic compounds by granular activated carbon as measured by the available surrogate parameters. Different isolation and identification techniques were compared; 'they demonstrated the use of gas chromatographic profiles as fingerprints of complex groups of trace organic compounds. The use of G C / M S was discussed as a qualitative'identificationtool. In contrast, the problem of relying on simpler analytical techniques to describe the routine performance of activated carbon columns was presented. A research overview Ten papers at the symposium dealt with pilot column case-histories, or an overview of on-going pilot-scale EPA research. Table 3 presents selected studies by location, with a synopsis of the project description and set parameters. Comparing brands of activated carbon, evaluating the ef-
TABLE 3
Pilot column studies Locatlon
Project parameters
U S . EPA
Review
Philadelphia, Pennsylvania
Empty-bed contact time, surface loading, chromographic effect, TOC, and total THM removal
Kansas City, Missouri
Five brands of carbon, time of year, virgin and regenerated carbon
River Trent and River Thames, England
Large- and small-scale pilot filters, six brands of carbon, downflow velocity, spiked influent with six organic chemicals
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Project description
An overview of in-house and extramural research by James M. Symons, with regard to three performance criteria from proposed regulations (43 FR 5756). A two-level approach discussed by Patrick R. Cairo, which incorporated laboratory- and pilot-scale results into a discussion of the adsorption mechanism. Results related to design data needs. The removal of total organic carbon (TOC), trihalomethanes, and precursor compounds from drinking water reviewed by John T. O'Connor. Removal of TOC, ultraviolet-absorbing materials, and specific organic compounds, described by R.A. Hyde.
fects of variable hydraulic parameters such as the emptybed contact time, linear velocity and bed depth and monitoring for organics removal were the major themes of these studies. One study reported on the possible difference in adsorptive capacity between virgin and regenerated activated carbons. But few studies used GC/MS to monitor removals of sub-part per billion concentrations or organic chemicals. However, these two areas are receiving increased attention now, and it will not be long before reports on their results are made. Laboratory-scale studies of a novel method for regenerating the activated carbon surface was reported by Michael Modell. This method uses supercritical carbon dioxide as a regenerating solvent. It is reported to exhibit more rapid mass-transfer characteristics than does a liquid. Laboratory tests have shown that after 30 adsorption-desorption cycles, the loss in adsorption capacity per cycle was less than 2%. Modell also said that it is possible to precipitate the solutes out of the supercritical fluid, thereby regenerating the fluid, and recovering the solutes in a concentrated form.
Options: biological activity on GAC or synthetic resins As previously stated, G A C treatment is the most effective “broad-spectrum” technique for removing trace organics from drinking water. However, two treatment techniques that are most frequently mentioned as alternative technologies are ozone-enhanced adsorption-biological degradation, which is also called biological activated carbon (BAC) adsorption with synthetic resins. The first process is really a combination of unit processes, including ozonation followed by granular activated carbon. It is hypothesized that ozonation of high molecular weight organic compounds produces more biodegradable substances of lower molecular weight, which the ever-present aerobic bacterial population on the carbon face can break down even further. Table 4 outlines the results from some of the papers presented a t the symposium, that covered topics including
a mechanistic overview of adsorption/biodegradation; a European survey of 21 BAC plants; pilot- and full-scale case histories; and a bacterial growth model. Widely varying results were presented, which indicated that preozonation/activated carbon treatment is a very complex process that must be further studied, and tightly controlled. Important process considerations that influence the system performance include the types of influent organic compounds, ozone dose, empty-bed contact time, effects of pretreatment, and of the nature of the biomass on the carbon surface. Adsorption with macroreticular or anion exchange resins is the second alternative technology for removal of organics that was addressed at the symposium. One of the most interesting papers of the symposium was given by James Neely, who discussed the adsorption mechanism for organics on “Ambersorb XE-340.” That material is a carbonaceous adsorbent that is produced by the partial pyrolysis of beads of macroreticular synthetic polymer. This polymer is substituted with a carbon-fixing moiety. Dr. Neely proposed that the high capacity of the XE-340 resin was caused in part by the ability of the resin bead to swell. Several studies have indicated that XE-340 resin has a much higher capacity for chloroform, as compared to that of the activated carbon adsorbents. For the adsorption of much larger molecules, such as humic acids, however, activated carbon is still the adsorbent of choice. The XE-340 resin suffers from a very high initial cost that might limit its use in water treatment. Nevertheless, an economic analysis presented by Frank L. Slejko suggested that the use of XE-340 resin may be economical if a certain set of assumptions prove to be valid.
Case histories and design needs The state-of-the-art of activated-carbon column design for water treatment plant applications was presented by Michael McGuire. Since there are no widely known examples of full-scale applications for removal from organics from drinking water, the experience that has been gained in related carbon applications in the U S . and full-scale carbon experience in Europe must be used to provide guidelines in design criteria. Examples from U S . advanced
TABLE 4
Adsorption/biological degradation interaction Location
General
Europe
Cleveland, Ohio
General
Morsang-sur-Seine, France
Proiect parameters
Project description
Andrew Benedek presented an overview of the influence of biological activity in an activated column. G. Wade Miller presented the results of a recent tour of 21 plants that use carbon columns preceded by ozone. Enhanced carbon life, and arnmonia oxidation to nitrate were noted. Pilpt plant results were explained by R. Prober Process parameters modeled in a pilot in terms of basic principles. These results inplant for advanced waste treatment; volved partial ozonation of organics, carbon ozone preceding activated-carbon surface oxidation, and the overall effect on adcolumns sorption and biological degradation. A bacterial growth model was presented by Chi Bacterial growth and the interaction with Tien, based on the diffusion of organic substrates adsorption on carbon throagh a film. Adsorption with and without preozonation, Frangois Fiessinger reported full-scale results on preozonation of carbon columns. Enhanced several forms of organic compound organics removal was noted. removal
Organic fraction removed, adsorber life, biodegradation rates, operational problems Review of European experience with ozone followed by carbon columns
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waste treatment and industrial applications were presented, as well as related data from water treatment plants to develop the needed design criteria. Noel Brodtmann of the Jefferson Parish Water Quality Laboratory (La.) reported on the performance of two full-scale granular activated carbon filters. The filteradsorber and the post-filtration adsorber were evaluated on the basis of removal efficiencies for a large number of individual organic compounds, as well as for certain classes or organic materials. The effects of cold lime softening and different forms of chlorine for disinfection were studied as variables in the treatment sequence. A case history of the design of a 282-mgd granular activated carbon facility was presented by Patrick Cairo for Commissioner Carmen Guarino of the Philadelphia Water Department. Pilot-scale studies using columns and filter adsorber units were described and used to develop the design parameters. Carbon contactor units and regeneration systems were examined for their design flexibility. A thorough economic study including a sensitivity analysis was presented to test the significance of the cost estimates for the various alternative configurations. Aaron Rosen of the Cincinnati Water Works discussed the major phases of a predesign study that the City of Cincinnati is undertaking, that will ultimately result in full-scale carbon treatment of the water supply. Sand replacement in the filters was compared to post-filtration pressure contactors. In addition, an on-site carbon reactivation furnace was included as part of the study. In addition to providing protection against chemical spills on the Ohio River, granular carbon filters in the water treatment plant will be used to remove trihalomethanes. Small-scale pilot columns were evaluated in parallel to the converted sand filters to determine if the large-scale results could be reproduced in the smaller filters.
“New for user and designer” “GAC is a new technology for the user and designer, rather than for the maker,” Don Hager, formerly general manager of Calgon’s Environmental Systems Division, and now with the firm of Rubel and Hager ( R & H , Tucson, Ariz.), told ES&T. H e said that many chemical engineers have never covered adsorption during their training, to any great extent. For this important reason, also, there are not many people in the potable, or drinking water treatment (dwt) and wastewater treatment (wwt) fields, who have much experience in that line. Thus, “it is not always easy to impart a full understanding of GAC, especially among designers and users,’’ Hager said. But this barrier to understanding will have to be, and will be overcome, especially if EPA’s proposed drinking water standards do take effect. If that happens, G A C use will increase sharply, as will the need for, and the amount of people who understand its applications. Hager said that GAC use may expand slowly, at first; but that its use could well begin to accelerate sharply. H e estimated that in five years, GAC use for dwt could reach 50 million Ib. For this year, Hager pegged G A C use in dwt systems a t 12 million Ib. On the other hand, consultant AI Hiltgen of Marketing Assistance, Inc. (Inverness, Fla.) pegs 1978 dwt use at 75 million Ib, to handle trace trihalomethanes ( T H M ) and synthetic organic chemicals.
ES&T’s Julian Josephson In the US.,producers of granular activated carbon (GAC) and powdered activated carbon (PAC) are Barnebey-Cheney (Columbus, Ohio, recently acquired by Pennwalt Corp.); Calgon Corp. (Pittsburgh, Pa.); Husky Industries (Dunnellon, Fla.); IC1 America (Marshall, Tex.); Union Carbide (Fostoria, Ohio); Westvaco (Covington, Va.); and Witco (Petrolia, Pa.). Last year, their total sales were about $95 million, with projected growth of 7-1O%/y in sales, and 557% in unit volume. Total output was on the order of 207 million Ib (1 80 million Ib, if one excludes vapor-phase carbon). The Carborundum Co. is entering the G A C field, and expects to have an initial capacity of 25 million Ib/y at its new Pryor, Okla., plant, starting next September. The carbon will be made from a variety of coals, by a proprietary process. Carborundum will add its capacity to the industry’s total capacity of 290 million Ib/y. And IC1 America has announced a 40% expansion of its G A C and PAC facility, scheduled for startup next year.
The main GAC and PAC markets Hager believes that if EPA’s proposed dwt regulations go through largely as envisioned, the main market for activated carbon-especially GAC-will be municipal. However, he notes that the time frame for purchase and installation of this technology, aimed principally at removing trace trihalomethanes (THM) and synthetic organics, should be considered uncertain. For instance, compliance dates could be affected by the very strong resistance which many municipal and private water utilities are putting up against proposed dwt rules. Hager estimated this year’s municipal G A C market at $12 million; and the industrial G A C market at a like amount. Should the controversial EPA rules come into being, however, he expects the municipal market to pull ahead, because of the boost from dwt requirements. But municipal wwt would also be an expanded market, because of the frequent classification of G A C as “best available technology” (BAT), as required for 1984. To be sure, the industrial wwt market would also grow because of the BAT feature, but Hager said that it is too early to hazard a guess as to what the 1984 municipal/industrial G A C market proportions might be. J. William Breen, marketing manager, and Michael Massey, product manager, wastewater treatment at Westvaco’s Chemical Division, counseled caution in trying to project market trends. They reminded ES& T of sanguine expectations for a greatly expanded activated carbon market-expectations engendered by the passage of the Federal Water Pollution Control Act Amendments of 1972.
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Activated carbon is made in Europe, as well. For instance, Calgon has facilities in Belgium and England. “Picactif TE” is made in France. And Norit, N.V., of Holland, is a company specialized in activated carbon; Norit makes both G A C and PAC. In the U.S., the three major producers-Calgon, ICI, and Westvaco-make both PAC and GAC. IC1 and Westvaco produce more in the way of PAC, while Calgon leads in GAC.
Activated carbon-some of its business and technology Aqua Media Aqua Media (Sunnyvale, Calif.) manufactures reverse osmosis (RO) and deionization equipment to treat industrial process water, and wastewater. The company explains that activated carbon is used to remove chlorine, low molecular weight organics, and partially dissolved gases from process water. Activated carbon is also used to remove trace organics and proprietary cleaning solution from reclaimed water supplies, according to Aqua Media. Calgon Calgon has a 3-year “service” contract for a G A C adsorption system to control offensive taste and odor in drinking water supplied by the Lee County Water Plant at Olga, Fla., near Fort Myers. The plant processes 3 mgd of water from the Caloosahatchee River, and serves about 30 000 persons. The water’s taste and odor problems stem from heavy algae growth in the river water. There are three specially-designed adsorption vessels which use a total of 60 000 Ib of FiltrasorbB 300 G A C made by Calgon. The initial carbon fill is expected to last one year before replacement. Lee County contracted for the service agreement by which Calgon installs/maintains the equipment, and replaces exhausted carbon. A monthly fee pays for these services. According to Calgon, the need for a major capital outlay by Lee County was thereby eliminated. Calgon’s G A C adsorption processes are also helping to achieve a goal of “zero discharge” for a specialty chemical plant operated by Alcolac, Inc., at Sedalia, Mo. ( E S & T , August 1978, p 877). W A P O R A , Inc. (Washington, D.C.) designed the wwt system. Met-Pro Met-Pro Corporation’s Systems Division (Harleysville, Pa.) has provided many of their Independent Physical/Chemical (IPC) advanced wwt systems for treating domestic waste. Typical of their systems is one recently installed at the Vail Ski Resort (Vail, Colo.), which treats 50 000 gpd. These systems utilize GAC, following chemically-aided clarification. The
G A C was supplied by Westvaco. The systems are furnished completely assembled, including piping, wiring, and controls for flows up to 300 000 gpd. Carl Janson, sales manager for the Systems Division, notes that G A C is more expensive than PAC, on a pound-for-pound basis, but “the G A C has a higher loading capability; and when overall economics are compared, G A C comes out ahead. G A C is also easier to handle, as it has little dust,” Janson said, “and fewer pounds need to be utilized for a given job, resulting in less effort by the user.”
Westvaco Westvaco’s first fluidized-bed G A C regenerator has successfully undergone startup at Hercules Inc.’s Hattiesburg, Miss., chemical plant. Hercules had been using G A C for years for industrial wwt, and regenerating it in a multihearth furnace. Costly furnace repairs and down-time caused Hercules to look for on-site regeneration alternatives. Thus, Hercules chose to retrofit the first Westvaco Fluid Bed Regeneration Process into its system. Since startup, the unit has operated above design rates, according to Westvaco’s Breen and Massey. Westvaco has received contracts
to install regenerators at Manchester, N.H., and Cincinnati, Ohio, to process GAC used for dwt. Breen and Massey say that while the fluidized-bed regenerator probably would not sell for less than a comparably-sized multi-hearth furnace, there are a number of operational advantages. These are a halving of fuel consumption, less need for maintenance, and easier startup/shutdown.
Zurn Zurn Industries, Inc. (Erie, Pa.) is to design and supply equipment for a carbon adsorption system to handle 1 mgd of drinking water for the City of Cincinnati, Ohio. The system is to remove synthetic organic pollutants, and is one of the first such systems, sponsored by EPA, to do so on a relatively large scale. It will have a great degree of operating flexibility, in order to determine the best configuration and modes of operation, George Strudgeon, vice president and general manager of Zurn’s EnviroSystems Division, told ES& T . Zurn is also supplying a carbon adsorption system to the 30-mgd Garland, Tex., project. That system uses a novel upflow-downflow approach developed by Strudgeon and Andy Loven. It uses IC1 America’s “Hydrodarco” carbon.
How GAC removes ttihalomethanes Existing planP
Fittration “Plug-in” packaged carbon treatment system
I
1Backwash recycle
I
I
I
Influent from
Treated effluent
filters
Backwash Pump
I
Q
From clearwell
w
(for regen
eration)
Influent
I
BAt Cincinnati, Ohio Source: Zurn Industrrs, Inc
1 I
I
Automated valves
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Because of that la‘w, certain producers of coal-based GAC doubled their capacity. The result was an overcapacity, because the GAC market did not grow as expected. Breen and Massey see where this overcapacity could be further increased, if new producers enter the G A C field in anticipation of dwt markets which subsequently do not grow in the amount or time frame foreseen. Breen and Massey observed that while GAC is specified as the treatment technique to remove trace synthetic organics, it is a treatment alternative for removing trace THM. Thus, they feel that T H M treatment is a “potentially large” market for PAC, as well, to be used for removing T H M precursors before chlorination.
Keep your powder wet! A different situation exists in the case of PAC. For example, Westvaco’s Breen and Massey gave ES& T an estimate that PAC use for control of taste and odor in dwt was 40 million Ib in 1968, and will be 30 million Ib for this year. They said that the decline was occasioned by improvements in raw water quality, as well as by the municipal money crunch. However, they are optimistic about PAC’s future as a means to control T H M . On the other hand, R&H’s Hager looks for a “modest” growth, or stabilization of the PAC market in dwt and wwt. But he said that for most municipal applications, he expects that PAC may give way to GAC. Hager explained that PAC is applied to drinking water or wastewater “as a dose,” whereas GAC is packed in columns through which the water must pass. In the case of wwt, he said that the spent PAC becomes part of the sludge, which must be removed, and is normally not regenerable. O r is it not regenerable? PAC regeneration Perhaps there are ways around the sludge and nonregenerability characteristics of PAC. For instance, Zimpro Inc. (Rothschild, Wis.) says that for wwt, at least, there are. Zimpro spokesman Jim Force explained how the secondary sludge disposal problem is eliminated with his company’s biophysical Wastewater Reclamation System ( E S & T , September 1977, p 854). The trick is to add PAC to activated sludge aeration basins where physical adsorption and biological treatment are accomplished together. The PAC used is supplied by ICI. The next step is to “waste” spent PAC and associated biomass to a wet oxidation unit where, with compressed air at 1200 psig and 200 OC, about 80% of the waste biological suspended solids are effectively destroyed; the remainder is stabilized. There, the spent PAC is regenerated, up to 95%. Wet oxidation selectively oxidizes spent sludge organics, thereby limiting PAC losses. Such systems have been operating successfully in Japan for more than one year. In the US.,Zimpro’s technology is soon coming on line at Vernon, Conn., and at a 10-mgd wwt plant in Medina County, Ohio (less than $3.5 million). And at Burlington, N.C., an 86-gpm system, costing $4.1 million, is specified; Force says that it is expected to reduce BOD below 5 mg/L; ammonia nitrogen below 1.5 mg/L; and total Kjeldahl nitrogen below 3 mg/L. Force points out that Zimpro’s work with PAC involves, principally, municipal wwt. However, he sees wwt applications as a “coming thing,” and expects the PAC market, and his company’s involvement in it, to grow. At its Chambers Works at Deepwater, N.J., Du Pont has 1144
Environmental Science & Technology
had a PAC regeneration process, known as the PACT Process, in operation for about one year. A continuous process, it works as part of the Chambers Works’ 40-mgd wwt system. IC1 and Westvaco furnish the carbon.
Use and cost projections: everyone seems to make his own R&H’s Hager estimated that as of this year, for dwt, the number of plants using PAC is 10 times the number using GAC. Some 33 dwt plants used GAC for taste/odor control as of January. As for GAC itself, Hager estimated that wwt use of all types exceeds dwt use by five times. Whether these proportions will remain the same is problematical. One factor clouding any attempt at a forecast is the effects of any dwt regulations concerning T H M and synthetic organics that EPA may set forth. Also, if EPA’s proposed rules come into effect, what might costs-part of which would go to purchasing activated carbon-be? Some federal government estimates are as low as $6-27/family/y. Many others outside the “fed” say that a more likely figure is $lOO/family/y, which comes to about 30$/family/d. Hager says that 30Q/d might conceivably be accepted, because safe drinking water is, after all, high on a person’s or family’s priority of needs. Discussing the “big picture,” many opponents of EPA’s proposals talk about nationwide capital costs of $350-450 million, with operating costs of $60 million/y. And some water utility spokesmen predict costs 6-10 times those figures.
Is a carbon service the way to go? Hager suggested that one way to ease some of the capital cost burden might be to contract for a service, such as one that his former company, Calgon, offers for a monthly fee (ES&T, October 1976, p 974). H e said that in consideration of that fee, Calgon stands ready to provide a whole range of dwt or wwt services, including installing the equipment; assuring a GAC supply; regenerating the GAC; and monitoring what goes into, and comes out of the GAC columns. On the other hand, Westvaco’s Breen and Massey believe that on-site GAC regeneration will be the most economical alternative for the large municipalities likely to be required to install G A C under proposed EPA rules. “We do not see a service package approach as a serious alternative for the dwt industry in the future,” they told E S & T.
They use BAC in Europe At the ACS symposium, Irwin Suffet and Michael McGuire discussed ozone-enhanced adsorption-biological degradation, also known as biological activated carbon (BAC). In fact, this BAC technology has been in use in Europe for several years. One reason it was needed was the very poor quality of raw water in many European localities. Some 20-30 dwt/BAC plants are in use in Europe. A typical example is Diisseldorf, W. Germany, whose plant is 10 years old. And a 100-mgd plant-more than 1000 metric tpd-will come on line at Rotterdam, The Netherlands. Work done by jVagdy Guirguis, former director of R & D for the Cleveland Regional Sewer District, indicates that G A C made from lignite performed best for the BAC application. H e attributed this performance to the pore structure of such carbon, which he said is more conducive
it follows that he will be forced to make decisions that are frankly judgmental. Absent the luxury of absolute scientific, technical, legal and economic certainties, he must, in keeping with the protective intent of the law, make these judgmental decisions on the side of public health.
GAC regeneration. Furnace at Diissrldorf, W. Germany
to biological activity. Incidentally, IC1 makes lignite-based GAC. This technology is not yet in greater than pilot use in the U.S. In the future, it could come, but that would necessitate a Europe-US. technology transfer operation, which got a good start from the ACS Meeting symposium described by McGuire and Suffet. However, the principles of BAC systems are now known and proven, as are those of G A C systems, and P A C applications and doses. The technologies are certainly familiar to their producers, and should eventually present few problems to users, aside, perhaps, from the costs. It is only a question of time.
ES&T’s Lois R. Ember It began with the muddy Mississippi River and the potentially carcinogenic industrial and agricultural contaminants that its currents carry to the City of New Orleans. For such was the fear-engendering force of that polluted river’s flow that it was soon transformed into political pressure, to emerge, in record-breaking time, as the Safe Drinking Water Act (SDWA) of 1974. A cursory reading of the Act would suggest that EPA and its administrator were given unprecedented discretionary powers and unlimited flexibility in carrying out its mandate. The Act, in fact, does state that the administrator must promulgate regulations for those contaminants which he determines may adversely affect human health. It does not stipulate conclusive scientific proof as a prerequisite to regulation, but it does prescribe the form of regulationeither a maximum contaminant level (MCL) or, if this level is technically or economically infeasible, a mandatory treatment requirement. Russell Christman, an environmental scientist intimately familiar with the Act-he was an original member of the National Drinking Water Advisory Council-has characterized it as “unique in the lack of flexibility given to the regulatory agency with regard to either the selection of contaminants to be regulated or the manner in which they should be regulated.” Given this inflexibility, and the fact that the administrator must regulate a t the suspicion of human health risk,
Health-effects information was inadequate On December 24, 1975, EPA promulgated National Interim Primary Drinking Water Regulations, which became effective on June 24, 1977. These interim regulations set MCLs for only six pesticides. N o other organic contaminants were regulated because, EPA claimed, the agency a t that time did not have adequate health-effects information on which to base such regulations. In September 1976, the Environmental Defense Fund (EDF) filed suit in the U S . Court of Appeals for the District of Columbia to force the agency to promulgate interim regulations for the myriad organic contaminants found in drinking water. On February 10, 1978, the court upheld the administrator’s action of not including more comprehensive organic contaminant control measures in the interim regulations. But the court also stated that incomplete health-effects information “and the imperfect nature of the available measurement and treatment techniques cannot serve as justification for delay in controlling contaminants that may be harmful.” While the court was deliberating, additional scientific information was being amassed. Toxicological and epidemiological studies, whose findings were assessed by the National Academy of Sciences (NAS) in its June 1977 report “Drinking Water and Health,” suggested that trace organic contaminants in drinking water posed a potential human health risk. Buttressed by this accumulating but not conclusive evidence, the EPA on February 9,1978, one day before the appeals court ruling, issued a proposed amendment to the interim regulations to control these contaminants whose control Victor Kimm, deputy assistant administrator for Drinking Water, has said “takes us to the very limits of current scientific knowledge.” A two-pronged approach The agency recognized two prime classes of potentially hazardous organic contaminants-the by-products of conventional chlorination practices; and those synthetic organic chemicals present in upstream industrial discharges, and in agricultural or urban runoff-and chose to control each class differently. Both parts of the regulation apply initially to cities with populations greater than 75 000. At this population cut-off, EPA estimates that about 60 cities, serving 52% of the U S . population, will be affected by the proposed regulation. For the trihalomethanes (THM), the by-products of the reaction of the disinfectant chlorine with natural humic materials in the water, the EPA proposes an M C L of 100 pg/L or 100 ppb, which can be achieved by any reasonable means, provided adequate disinfection is maintained. According to Joseph Cotruvo, director of the Criteria and Standards Division within EPA’s Office of Drinking Water, the agency’s issuance of an MCL for T H M is less restrictive than a treatment requirement would have been because the affected utility can meet the M C L by whatever means it chooses. Further, Cotruvo says, T H M s can be monitored and, therefore, “the appropriate standard under the Safe Drinking Water Act is a maximum contaminant level.” For those water systems likely to be contaminated by Volume 12, Number 10, October 1978
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synthetic organic chemicals, the proposed regulation refully chuckled that no city in his state is large enough to be quires a treatment technique: GAC or an equivalent affected by EPA’s proposed regulation. method. Water utilities may seek a variance from this “Spirited comment period”: EPA was treatment requirement, but they will have to supply monitoring data to show that their water supply comes from a surprised by the strong response! protected source; water comparable in quality to that of the EPA considers its proposed two-part approach to the Great Lakes, deep underground aquifers or protected rescontrol of organic chemicals a reasonable and economically ervoirs would probably qualify for variance. Also, alterfeasible first step. The outcry from the water works indusnative treatment methods that can be shown to be as eftry, however, was fast in coming and strident in tone. Surfective as GAC will be allowed by variance. prised by industry’s reaction, EPA candidly admits that the Why did EPA propose a treatment requirement rather opposition was “stronger than anticipated.” One indication than individual MCLs for these pollution-related organic of this opposition is that at the close of the comment period chemicals? According to EPA’s interpretation of the law, last month, the agency had received about 500 comments in the absence of a treatment requirement, MCLs would plus 350 congressional inquiries. have to be written for a significant number of chemicals Thomas C. Jorling, assistant administrator for Water and identified in drinking water, and these would have to be Hazardous Materials, speaking to the 98th annual meeting applied uniformly throughout the U S . Further, MCLs of the American Water Works Association (AWWA) on would require monitoring on a regular basis, which is exJune 26 categorized the most frequently received comrrients pensive; they would require that all public water systems into four themes: monitor, unless an exemption mechanism could be found “The health effects data are not a sufficient basis for to eliminate some systems from this requirement; and they action. would require that a water system meet the MCLs or be EPA’s estimated costs of using G A C are grossly undeclared out of compliance. For these reasons, the MCL derestimated. route seemed to offer utilities less flexibility and, therefore, 0 The regulations should not be promulgated because the agency opted for the treatment requirement. of their secondary effects on energy consumption and air The agency chose the 75 000 population cut-off for three pollution. reasons, not all of which were explicitly stated in the proThere are risks and possible bad side-effects in the use posed regulation. First, the SDWA was clearly written with of granular activated carbon.” large-system economics in mind. Cities with populations EPA addressed these themes in its white paper, which it of 75 000 or greater supposedly have the financial and published in the Federal Register on July 6 . After reextechnical wherewithal to monitor water supplies and operate amining its proposed regulation, the agency succintly sophisticated treatment plants. Second, at this cut-off, about concluded that the secondary effects on energy consumption one-half of the U S . population is protected. Third, this and air pollution, and the potential side-effects of G A C cut-off captures, under regulation, many of the cities the would be minimal. On the scientific and economic bases for EPA knew had waterborne pollution problems. the regulation, however, the agency went into some deEDF’s attorney Jacqueline Warren, however, argues for tail. a much lower cut-off point, stating that “safe water should The scientific evidence be provided for all citizens regardless of the size of the community they live in.” Senator Edmund Muskie (D, For its health-effects data, EPA drew from both animal Me.), at oversight hearings which he chaired in July, ruetoxicological (bioassay) studies and from human epide-
Proposed organics regulations A Maximum Contaminant Level (MCL) of 0.10 mg/L for THM This is initially applicable to community water systems serving more than 75 000 people. Monitoring requirements for these systems would become effective 3 mo after the date of promulgation. The MCL would become effective 18 mo after promulgation. Systems serving 10 00075 000 people would be required only to monitor for THM, beginning 6 mo after promulgation. Systems serving fewer than 10 000 people would not be required to monitor for THM. Additional microbiological monitoring would be required if treatment practices are altered to
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comply with the regulations. Limits would be placed on the use of chloramines and chlorine dioxide as alternative disinfectants to chlorine.
GAC effectiveness criteria for systems vulnerable to significant contamination by synthetic organics: Concentration in the effluent, of any volatile halogenated organic compounds, excluding THM, is not to exceed 0.5 pg/L. Removal of total organic carbon in the influent, with fresh activated carbon, shall be a t least 5oom. Effluent total organic carbon may not exceed the value with fresh
activated carbon, by more than 0.5 mg/L. Those water systems required to install the G A C (or alternative) treatment technology would be expected to have that technology in operation within 395 years after the effective date of the regulation. Pilot studies should be begun within 6 mo of the effective date. Within 18 mo, the system would submit its final design, plans, specifications, and construction schedules to the state, or to EPA for apppoval. The G A C application might include post-filtration contactors, or replacement of existing filter media with GAC. Source: Suffet and McGuire (p 1138).
departments. Industry, on the other hand, finds insufficient scientific evidence to support EPA’s regulatory stance.
EPA’s Jorling, Kimm, and Cotruvo (I to r) massaging the regulations
miological studies. In the proposed regulation, EPA clearly lays out its reasoning, and the problems associated with the methodologies underpinning its action. These can be found in 43 FR 5756; in EPA’s statement of Basis and Purpose; and in NAS’ “Drinking Water and Health.” Chloroform, only one of the many trihalomethanes formed during the disinfection process, has been confirmed a carcinogen in rodents in several studies. Other organic compounds found in drinking water-carbon tetrachloride, trichloroethylene, and vinyl chloride-have also been shown to be carcinogenic in bioassays with rats and mice. In its position paper supporting the EPA regulation, N C I cites nine epidemiological studies that showed “a number of statistically significant associations between water quality and cancer,” and three studies in which THM levels were quantified which tentatively concluded that “bladder cancer, and perhaps large intestine cancers are correlated with trihalomethanes in the water.” One of the latter quantitative studies, the N C I states, “leads to the conclusion that a decrease of 100 pg/L of chloroform in water could lead to a decrease in [bladder and large intestine] cancer rates. ” Working from a 1976 list of organic contaminants in drinking water, the N C I identified 23 as carcinogens or suspected carcinogens, 30 as mutagens or suspected mutagens, and l l as promoters. Based on this evidence, NCI’s director Arthur C. Upton, in an April letter to EPA administrator Douglas Costle, lent his agency’s support to EPA’s proposed regulation: “We support the judgment that these chemicals present a potential risk of cancer that should be reduced to the extent feasible.” Upton did state that while it was not possible at present “to quantify the actual hazard from exposure to chemically contaminated drinking water or to determine the contribution to national cancer rates from drinking water,” these facts remain uncontested: “Chemicals which have been shown to cause cancers in animals studies are commonly found in drinking water in small amounts. Some known human carcinogens have been found in drinking water. Exposure to even very small amounts of carcinogenic chemicals poses some risk and repeated exposure amplifies the risk.” Additionally, chemicals that have been found to be carcinogenic in animals have later been shown to be carcinogenic in humans; and, with the possible exceptions of arsenic and benzene, the converse is also true. Moreover, since no thresholds for carcinogens have been demonstrated to date, the implication can be drawn that even low levels of exposure may contribute to the total cancer risk. The EPA is supported in its action not only by NCI, but by such other federal agencies as OSHA, FDA, CPSC and NIEHS, and by EDF, the League of Women Voters, Ralph Nader, and several state health agencies and local water
Utilities take strong issue George W. Pendygraft, an attorney with Baker & Daniels, counsel to the Coalition for Safe Drinking Water (an ad hoc group of 85 municipal and investor-owned water suppliers formed solely to fight EPA’s regulation), stated at the final EPA public hearing in July that “based on the data now available, the proposed amendment appears to us to be based upon fear, not upon fact.” Francis Roe, a British pathologist testifying at this same hearing for the Louisville Water Co., a member of the Coalition, stated that data from his studies in dogs, rats and mice led him to “believe that a negligible cancer hazard would be associated with the concentration of chloroform in water of 300 ppb, since this concentration would be less than 1/1000th of that [level] known to be without carcinogenic effect in the most sensitive of four strains of mice that we studied.” After reviewing Roe’s rodent data, NCI’s Cipriano Cueto, chief of the toxicology branch, concluded that Roe’s results could have been predicted from NCI’s statistical model. Cueto pointed out, however, that the probability of Roe being able to detect a carcinogenic effect in his study was small because of the low dose levels and the small number of animals used. Richard Reitz, testifying for Dow Chemical Co. at the July hearings, stated that EPA overestimated the carcinogenic risk associated with chronic, low-level chloroform ingestion. His reasons: “EPA has failed to consider important data which exist concerning the mechanisms through which chloroform exerts its toxicity. The N C I study was carried out with very high doses of chloroform. At slightly lower doses, the relative carcinogenicity of chloroform falls sharply. This suggests that there may be detoxification mechanisms which effectively protect the animals until they are overwhelmed by very large doses.” In its July 6 white paper, EPA outlines the scientific uncertainties, the difficulties of translating animal experimentation to the human experience, and the inconclusiveness of epidemiological studies, and still it concludes: “The approach EPA is taking in the drinking water proposal is consistent with the approach which these [NCI, NIEHS, FDA and OSHA] and other health-concerned agencies have taken in regulating human exposure to carcinogens, that is, to reduce human exposure to the extent feasible, provided the costs are reasonable.” The agency acknowledges that there are reputable scientists who do not accept the concept that there is “no safe level” for a carcinogen. But EPA, recognizing that this scientific issue will not be resolved in the near future, chooses to align itself with the other federal health-oriented agencies by taking the conservative position of “accepting the ‘no safe level’ conclusion, since this position is more protective of public health and the preponderance of scientific opinion supports it.” The cost of compliance Certainly, nothing in the proposed regulation elicited more controversy than the GAC treatment requirement and the costs that such treatment would engender. Estimating the costs of major undertakings is an uncertain business at best. In this instance, cost estimates varied as a factor of the number of systems affected and the basic assumptions made. Volume 12, Number 10, October 1978
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Initially, EPA and industry estimates differed greatly. After the initial comment period, EPA asked its economic analysts Temple, Barker & Sloane (Wellesley Hills, Mass.) to reevaluate the 1977 analyses. The agency took the unusual step of publishing the revised (higher) cost estimates in its white paper. Industry also recalculated its estimates. After these exercises, EPA and industry figures were generally in agreement, differing by less than 20% in the New Orleans case, for instance. T o adjust for inflation, certain types of fees (legal and financing), and to incorporate more conservative design parameters, EPA raised its national capital costs upward by 50-80%, from $352-585 million to $616-831 million. The effect on residential utility bills for a family of three is to raise the cost of water by $7-26/y, up from original estimates of $3-17/y. For its economic analyses, the Coalition retained the services of the consulting firm of Black & Veatch (Kansas City, Mo.), whose consultant Paul Haney testified at EPA’s July hearings. Haney’s firm estimated that national capital expenditures for G A C treatment would total $4.7 billion, and annual operating and maintenance costs would reach $400 million for 154 utilities. EPA estimated annual O & M costs (for 61 utilities) at about one-tenth this amount. In its presentation to the August meeting of the drinking water advisory council, the Coalition said that Black & Veatch now estimates the m e r a g e capital cost of G A C for the affected systems a t around $29 million. This puts the Coalition’s national capital cost ($1769 million for 6 1 affected systems) at more than twice EPA’s revised estimates ($616-831 million). Further, the Coalition estimates residential rate increases “on the order of 50-loo%,” an estimate with which the National Association of Water Companies concurs.
“A gross underestimate” In a question and answer period following her testimony before the House Subcommittee on Economic Stabilization, EPA deputy administrator Barbara Blum was asked by Rep. Stewart McKinney (R, Conn.) if the agency had “looked a t the economic impacts of these [organic] regulations?” Blum’s answer: “Yes, we have looked into the economic impact of those regulations. I will say our first analysis was considerably underfigured, and we have come out since then and refigured it. It was probably the worst underfiguring job we have ever done. We were about 100% off in our estimates.” However you choose to characterize EPA’s original economic analysis, it should not be overlooked that the agency did go back and “refigure it.” The agency even went so far as to retain the consulting engineering firm of Gannett, Fleming, Corddry, and Carpenter (GFCC) to prepare a “preliminary estimate of capital costs for GAC treatment a t New Orleans,” so as to be able to reconcile some of the differences between EPA and industry estimates. The Coalition, in its presentation to the advisory council, pointed out that GFCC’s capital costs estimates for New Orleans exceeded $ 5 5 million, and that EPA’s revised capital costs for New Orleans were only $32-40 million. The Coalition failed to mention, however, that its capital cost estimates for New Orleans were originally $89.8 million, later revised to $65 million. The actual costs for a specific system will depend on such variables as the raw water supply and the design of the existing plant; these costs will vary widely from system to system. But the actual aggregate (national) costs are likely 1148
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to fall somewhere between industry and EPA estimates. A little bit of arm twisting There has been much political maneuvering by the water works industry to thwart the promulgation of the proposed regulation or, at least, substantially modify it. This lobbying, to some extent, continues. However, a t least between EPA and AWWA, the stridency that characterized earlier confrontations has mellowed. The rapprochement came in June at AWWA’s annual meeting. AW WA’s position since February has shifted. Originally the association called for a goal not an MCL of 100 ppb for THM, and for four G A C demonstration projects in lieu of the G A C treatment requirement. Now it is calling for an MCL of 300 ppb for chloroform (not total T H M ) for all water supply systems and, as more information is gained, MCLs for individual trihalomethanes. Instead of a treatment requirement, t h e h W W A is asking that the EPA set MCLs for the 23 organic chemicals the N A S lists as carcinogens or suspect carcinogens. The Coalition offered no constructive alternative to the EPA proposal until the August drinking water advisory council meeting. There it stated that it does not believe that an M C L for T H M is necessary; but if one is set, it “should be no lower than 0.30 mg/L (300 ppb), and it should be made applicable to all community water systems.” In lieu of the GAC treatment requirement, the Coalition called for MCLs. During the public comment period, the Coalition and A W W A have feverishly lobbied individual congressmen, and have prodded congressional committees to schedule oversight hearings on the SDWA. The aim of all this political suasion: amendment of the Act. Curtis Stanton, AWWA’s president, told the July 18 oversight hearings of the Senate Subcommittee on Environmental Pollution, chaired by Sen. Muskie, that the means to reconciliation between EPA and the water works industry “is contained in the key phrase of the law’s opening paragraphs. It requires EPA to regulate contaminants that in its judgment may have an adverse affect on human health.” Stanton went on to say that the “one word, ‘may,’ is causing most of the difficulty. If a reasonable modification could be approved by Congress, the way would be paved to renewed cooperation between the utility-state-federal team.” Muskie, in his contemplative closing remarks, did not appear to be receptive to changes in the law at this time. He said: “The minute you move beyond what was done before, to require that something more be done, then you immediately venture into areas of the unknown, and the uncertain, and the unproved, and you advance as firmly as you can on the basis of the best evidence that you have if you expect to get anywhere.” H e continued: “If, in passing the
AWWA’s Stanton (4and Sen. Muskie ( r )
differed on the needfor change
Safe Drinking Water Act all you wanted was sanctification of the status quo, well, you didn’t need the Act. So somebody has got to make some judgments, take the risk of criticism, take the risk of moving into experimental realms . . . take the risk of imposing requirements that may prove burdensome and less than cost effective, but unless we do that sort of thing, how are we going to make any progress?” Another set of oversight hearings was scheduled for July 25 in the House Subcommittee on Health and Environment, chaired by Paul Rogers (D, Fla.). These hearings were cancelled and rescheduled for September. However, the likelihood of amendments to the S D W A emanating from this committee is slim because of the few days remaining in this legislative session, and the fact that Rogers is retiring from Congress a t the end of his term later this year.
The question is not “whether,” but “when” But what of the likelihood of EPA promulgating its proposed regulation? Since the law, as further interpreted by the courts, is very clear on the number of options available to EPA, the question is better restated as “When will a regulation be promulgated and in what form?” The public comment period closed on September 1. The earliest EPA could promulgate a standard is probably March 1979. However, several rumors have been circulating that contradict this date. One rumor says that EPA will not promulgate a regulation after the comment period but will promulgate an organics regulation with its Revised National Primary Drinking Water Standards, perhaps a year or two hence. Another says that EPA will, because of substantive changes in the proposed regulation, reissue the regulation and go through the whole comment period again. Despite these rumors, a good guess is that EPA will promulgate a regulation early next year. The form this regulation may take offers the most intriguing possibilities. Both Kimm and Cotruvo state repeatedly that no policy will be set until all comment is in and reviewed; they will, however, enumerate the various combinations and permutations. While it is entirely possible that the proposed regulation will be promulgated unchanged, it is unlikely. The greatest changes are likely to come in the most controversial aspect of the regulation-the G A C treatment requirement. Could be in two parts The regulation will probably be promulgated in two parts; the MCL for T H M will most likely be stipulated at 100 ppb. If a G A C treatment requirement for pollution-related organic contaminants is stipulated, the time schedule will probably be stretched out to permit implementation of the requirement, or to accommodate two- to three-year demonstration/pilot plant projects, followed by the construction and operation of the plants. With this new time frame, final operation of G A C plants would not occur for another eight to nine years; the proposed standard would see G A C plants in operation in five years, a time schedule the utilities claim is impossible to meet. At its August meeting, the National Drinking Water Advisory Council recommended an alternative approach to EPA’s proposed G A C requirement: animal studies to assess the potential health hazards of untreated raw water from highly vulnerable water supplies compared to raw water from protected water sources and effluent samples from the activated carbon filter demonstration/pilot-plant studies, which would run concurrently with the animal
studies. The Council assumed that these studies would take five years to complete; and, in the interim, EPA should promulgate MCLs for NAS’ 23 carcinogens. Should the administrator not deem this approach viable, the Council proposed that the G A C treatment requirement be substantially modified, especially as it concerns variances and the timetable for compliance. The Council’s alternative approach may persuade the EPA to alter substantially its proposed G A C regulation. Should EPA accept and implement the Council’s recommendations for animal studies and MCLs, the agency would have to reissue that portion of the regulation and go through another comment period. On the M C L for T H M , the Council supported the proposed 100 ppb level, but recommended that coverage be extended to communities of 10 000 and up. It is, therefore, conceivable that the current population cut-off of 75 000 will be lowered, a t least for this portion of the regulation.
Between a rock and a hard place As is evident from the foregoing, EPA is, quite literally, a sitting duck, much like the targets one sees at a carnival’s shooting booth. Its mzneuverability is restricted, and once it begins to move back or forth along that straight line fashioned by Congress and the courts, it becomes the target for industrial or environmental advocacy groups. Should EPA retreat from its proposed standard by substantially raising the M C L for T H M and/or stretching out the G A C treatment requirement to eight-nine years, EDF will most likely seek relief in the courts. On the other hand, should EPA retain or lower the MCL for T H M and/or require the G A C treatment without substantial modifications, industry is likely to sue. Both factions have their rifles aimed, cocked and ready to fire. The next move is EPA’s. Irwin H. Suffet is aprofessor of chemistry and environmental science at Drexel. He is a member of the executive committee of the A C S Division of Environmental Chemistry, and of the National Academy of Sciences’ Safe Drinking Water Committee. His research efforts are in trace organic analysis, fate of pollutants. and the chemistry of water treatment. Michael J. McCuire is a senior engineer with Brown and Caldwell, Consulting Engineers. Since joining Brown and Caldwell, he has been responsible for directing research and engineering activities in his specialty area of activated carbon, and for managing a wide variety of industrial waste projects.
Julian Josephson is an associate editor of ES &T
Lois R. Ember is an associate editor of ES&T
Volume 12, Number 10, October 1978
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