-Liquid acid and thus more effective use of acid. Although a crane truck will be required, one man can be trained to handle all the units in a single mill with consequent less training and supervisory expense and better control of metals content to streams. The cartridge method is generally to be preferred within its operational limitations. On the other hand, where very wide variance in rinse flow rates and copper content from tank to tank exists within a mill or where there are less than four tanks per mill, the fixed unit should be more practical.
operational factors, including labor costs, might then be made t o establish the merits of any particular process.
Acknowledgment The authors wish t o acknowledge the helpful suggestions of Harding Bliss of Yale University and J. C. Winters, Rohm and Haas Co., and the helpful cooperation of C. E. Potts and members of the staff of the American Brass Co. laboratory, where these studies were carried out.
Nomenclature
Conclusions
.
Industrial Wastes-
The recovery and disposal of copper and brass alloy metals from wash waters prior to passage into streams might be accomplished successfully by employing high capacity cation exchangers such as Amberlite IR-120. Either the sodium or hydrogen cycle may be used; however, current operation using spent regenerant acid as pickle make-up points t o a considerable economy if the hydrogen cycle is used. I n many cases a considerable saving might be realized. The major factor influencing capacity for copper and zinc is the relative amount of calcium and magnesium hardness in the raw water supply. This factor is particularly important where the copper concentration in the rinse water is relatively low. Where the elimination of metals is the primary concern without considering recovery, sodium cycle operation should be considered. Sodium cycle operation has the advantage of a greater capacity, less sensitivity to total hardness in rinse water, greater concentrations of toxic metals in the regenerant, more complete removal of trivalent chromium, and reduced acidity. Copper, zinc, and chromium could be precipitated from the waste chloride regenerant b y sodium carbonate. The precipitated metals may be recovered by chemical means or dumped. These studies have served t o emphasize the problems existing in the treatment of pickle rimes with ion exchange. It is suggested that a survey be made of the flow rates and copper contents of pickling rinses in representative brass &ndcopper sheet, rod, wire, and tube mills. Once these data are available, a n over-all cost estimate for each firm could be determined and plant designs suggested. A large scale pilot plant study to fully determine
v
Bed volume, cubic feet G = Flow rate, gallons per minute P = Capacity, pounds of copper per cubic foot H = Hardness of water, p.p.m. as CaCOa EM++ = Total divalent cations, p.p.m. as CaCOa = Operation costs, dollars O.C. = Pounds of copper per gallon Cu ZMo++ = Total divalent cation, pounds of copper per gallon =
Literature Cited (1) Beaton, R. H., and Furnas, C. C., IND.ENG.CHEM.,33,‘1500
(1941). (2) Beohnor, H.L., and Mindler, A. B., Ibid., 41,448 (1949). (3) Bliss, H., Chem. Eng., 54, No. 5, 128; No.6 , 100 (1947). (4)Bliss, H.,Chem. Eng. Progress, 44, 887 (1948). (5) Bliss, H.,Connecticut State Water Commission, Metal Inds. Memo., No. 42,43, 44 (1940). (6) Bliss, H., personal communication (February 1, 1949). (7) Dodge, B. F., Connecticut State Water Commission, Metal Inds. Memo. No. 23, 25, 27-35, 37-41. ( 8 ) Galloup, C . F., “Electrolytib Treatment of Brass Mill Waste Pickling Liquors,” doctoral dissertation, Yale (1941). (9) Hilbert, L. E.,Connecticut State Water Commission, MetaE Inds. Memo. No. 36. (10) Monet, G., Chem. Eng., 57, No. 3, 106 (1950). (11) Nelson, R.,and Walton, H. F., J . Phys. Chem., 48, 406 (1944). (12) Piret, E. L., and Carlson, R. W., Proc. Minn. Acad. Sci., 9, 70 (1941). (13) Selke, W.A,, and Bliss, H., Chem. Eng. Progress, 46,’509(1950). (14)Tyler, C., “Chemical Engineering Economics,” New York, McGraw-Hill Book Co.. 1938. (15) Vessalovski, V. S.,and Seligliei, I. A., Chemie & industrie, 35, 875 (1936). RECEIVED for review August 11, 1951. ACCEPTED January 2, 1952.
Sulfuric Acid Recovery from Waste Liquors F. J. BARTHOLOMEW, Chemical Conetructi~n Corp., 488 Madi8on Am., New York 22, N. Y. T h e current shortage of sulfur and sulfuric acid has prompted industry to give serious consideration to recovering acid from products that are now going to wastefor example, the iron sulfate-sulfuric acid solutions from steel mills and titanium pigment plants. A practical method is described for recovering the sulfuric acid of such solutions by concentrating the free acid, removing the iron sulfate by salting out, and then decomposing the sulfate for the recovery of the acid value it carries. The process is a development resulting from years of work on this
problem in conjunction with designing and constructing plants for the manufacture of sulfuric acid and other heavy chemicals and for the recovery of sulfuric acid from industrial wastes. Cost of water evaporation has always been a major cost in pickle liquor recovery. A new method of supplying heat to concentrate the liquor improves fuel efficiency and makes the recovery possibilities somewhat more attractive. The economic aspects of these problems are stressed because of increased prices of sulfur and sulfuric acid arising from their short supply.
A
dence of the importance of thiR basic chemical. So closely is ita production tied to the national economy that its sale is used as a measuring stick, like car loadings, to gage prosperity. In many of its applications sulfuric acid is completely consumed and be-
BOUT 75% of the sulfur that is mined or obtained in other ways is used for the manufacture of sulfuric acid. In 1950, more than 12,000,000 tons of sulfuric acid (100% HB04 equivalent) were consumed in the United States; this is sufficient evi-
March 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
541
Liquid Industrial Wastecomes a part of the manufactured product-for example, in the production of superphosphate and alum-but in other applications it is only partly consumed and a ivaste product containing unconsumed acid and dissolved impurities must be disposed of or restored to usefulness. A reduction in supplies of sulfur or sulfuric acid can be more than offset by recovering the acid that is going to waste. Many larger consumers of sulfuric acid, such :is the oil refinem, steel manufacturers, and producers of titanium pigment, are now faced with sulfur shortages and are making close studies of acid recovery procedures.
f111ER
LIQUOR
TANK
Figure 1. Acid Concentrator
The C,hemical Construction Corp. has been active in the field of waste acid recovery for more t,han 30 years. Chemico acid concentrators and sludge acid recovery plants of various types are widely known. I t has long been interested in the problem of recovering acid from steel mill pickling wast’e and has built and operated t’ivo large recovery plants in the United States for manufacturers of titanium pigment, who have a similar waste product,. The process used in the original installation has now been radically improved. One cannot accuse t,he steel companies of lack of interest in the subject of waste acid I P cowry. The matter ha:: been under investigation for years. T’v70rk of this kind has been sponsored by the American Iron and Steel Institute, but years of thorough study and investigation have not disclosed any important and practical improvements in pickling practice or any completely satisfactory methods of waste acid recovery that steel mills were willing to adopt, Standing squarely in the way of economical recovery is the cost of evaporating Iarge quantit’ies of water and disposing of iron sulfate for which there is no great market. First attempts by Chemical Construction Corp. to develop a commercial recovery process involved two steps: the evaporation of the water and simult,aneous neutralization in the same vessel, of the free acid with iron oxide dust and roasting the resulting sulfates under r e d u c i n g con d i t i o n s t o produce sulfur dioxide gas which could be processed to produce fresh sulfuric acid. The process proved fea,-ible and two cornnicrcial plants were built. After some gears of operation, changing labor contlitions and other attending circumstances finally led to their abandonment. Excessive operat,ing and maintenance costs niadc the eo& of recovered acid higher than acid produced directly from low cost sulfur and acid dumping was resumed. The process had its shortcomings. The invgstment was high and the type 542
equipment used made upkeep costlj- even a t labor rates anti prices in effect in the late thirties. With comparatively stable sulfur prices and a steady improvement in design of sulfur-burning contact plants, it was more economical to produce acid requirements from sulfur and throw away the waste. KO plants of this type were built for the steel industry. Steel mill pickle liquor varies rather widely in acid and iron sulfate content because of the variation in pickling practice in the industry. Strong sulfuric acid is not effective for pickling for the simple reason that steel and ferrous sulfate are bot,h insoluble in strong sulfuric acid. Pickling, therefore, must be done with hot, weak sulfuric acid and, when the pickling action of the acid is spent, common practice is to run it to waste, with or without neutralization, depending on local circumstances. In most mills pickle liquor is run to waste when the acid content is about 5 to 8% and bhe iron sulfate, calculat,ed as FeSO4, is about 15.0%. Our present concept of a suitable recovery process is that it should return the free acid to the pickling vabs and convert unmarketable iron sulfate to fresh sulfuric acid and sintered iron oxide suitable for charging the blast furnace. With this concept in mind, Chemical Construction Corp. made a fresh assault on t,he problem. In the earlier work it was found that if the acid in pickling liquor was concentrated to about OO%, the ferrous sulfate dropped out in a crystalline form, easy to filter and wash. Also, the sulfate deposited from this strength acid had a relatively low water content and was suitable for further processing. Acid concentration was not a new problem, but concentrating acid saturated Tyith salts was a new problem, involving difficulties not previously encountered. It was necessary, therefore, to dcvelop a new technique, bearing in mind that fuel efficiency is of utmost importance becausc of the heavy cost burden of evaporating large quantities of water for the recovery of small quantities of acid. Indirect application of heat to thc salt-saturated arid
Figure 2.
Sulfate Sintering Operation
was out of the quest,ion. Submerged combustion seemed logical, but there was no satisfactory burner on the market. A burner known as the Swindin burner had been used to a limited extent in England for this purpose. License rights for its use were acquired and then the design was modified to increase its fuel-consuming possibilities for large scale operation. After considerable preliminary work had been done on a laboratory scale to test the various steps of the complete process, plans were made for a semi-
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
Vol. 44, No. 3
LJquid Industrial Wastecommercial unit, designed to handle, daily, 50 tons of spent acid from titanium pigment operations. The unit was installed a t Piney River, Va., where waste liquor of proper quality was available in continuous supply, and a contact sulfuric acid plant, already installed, simplified the processing of the sulfur dioxide gas to sulfuric acid.
Figure 3.
Extruded Pellets of Ferrous Sulfate, Iron Oxide, and Coal
Waste acid available here contained about 12% sulfuric acid, 20% ferrous sulfate, and the balance water. A cone-bottomed steel tank, lead- and brick-lined, served as the concentrating vessel and a combustion djp pipe fired with light fuel oil supplied the heat for the evaporation of the water (Figure 1). The unit was designed for continuous operation with waste liquor charged in a steady stream; part of the circulating magma, consisting of precipitated ferrous sulfate and concentrated acid, was continuously withdrawn for filtration of the solids. A vacuum filter of the Oliver Rotary type, constructed of lead and with plastic filter cloth, filtered the sulfate and washed the filter cake. The filtrate, containing about 60 to 70% sulfuric acid and about 1% iron sulfate, was sent to storage for re-use. The filter cake of iron sulfate was mixed in a pug mill with about 12% of its weight of coal and a quantity of crushed oxide from the Dwight Llo d sintering machine and then was extruded through a perforatez plate t o form l/d-inch diameter cylinders which broke off in lengths of to ‘/z inch (Figure 2). The extruded pellets fell directly on a moving grade for drying and then on the sinter machine on which a protecting coat of roaster cinder had already been placed (Figure 3). The dried pellets were ignited from above while air was drawn down through the bed. The coal in the pellets supplied sufficient heat to decompose the ferrous sulfate into sulfur dioxide and iron oxide. Incipient fusion of the magnetic iron oxide took place and the material was discharged in large porous chunks (Figure 4). A portion of the sinter discharged from the machine was diverted to a rough crusher and then conveyed by belt and elevator to a screen where the oversized particles were returned to the hearth layer bin, and the undersized fines were discharged to a secondary crusher and thence elevated to the sinter fines bin for the extrusion mixture. The sintering machine wind box was divided into two parts: Strong gas averaging about 7.5% sulfur dioxide from one portion w a s sent through a scrubbing tower and then through a coke box after which i t was suitable for processing in the contact sulfuric acid plant. The gas from the other section, containing very little sulfur dioxide was circulated over the drying section where it dried the pellets as described and then was discarded; it rontained less than 0.1% sulfur dioxide. With certain modifications, this is the process offered for commercial operation. Blast furnace dust could be used instead of coal on the sintering machine and pyrites would also make a suitable substitute for coal at this point and would have the added advantage of providing sulfur dioxide gas for make-up acid. As a matter of fact, it would be a simple step to enlarge the roasting, gas purification, and contact plant equipment to handle a substantially increased quantity of pyrites and produce any desired amount of acid. The process described is a practical one. If carried through all its steps, a recovery of 85 to 90% of all the equivalent acid in the pickling liquor. including that of the ferrous sulfate, may be ex-
March 1952
pected. Even the steel that wohld ordinarily be lost by pickling is returned to the mill as a by-product, not fully, of course, but to a substantial extent. Viewed from an economic standpoint, one must take into consideration local governing factors. A recovery plant might be economically feasible a t one location and completely impractical a t another. Recovery units of very low acid capacity are impractical for obvious reasons, although unusual attending circumstances may justify their installation. For large units there are other factors to be considered. Because of the water evaporation step, fuel is one of the largest items of cost and, therefore, pickling procedures have an important bearing on the economy of recovering the waste liquor. Unnecessary dilution of the pickling liquors, not only adds to the cost of reclaiming the acid, but adds to the investment required for the equipment. Every additional ton of water to be evaporated per day adds nearly 20 gallons of oil to the fuel requirement and about $1300 to the investment. The author is not qualified to advise on pickling procedure, but believes that, with x-aste acid recovery in mind, present methods of pickling can probably be changed to improve recovery economics. Neutralization of waste acid before dumping is a “must” a t certain locations, and this is a very substantial item of cost since the acid equivalent of the ferrous sulfate must be neutralized as well as the free acid. The cost of hauling waste acid to sea cannot be written off lightly. The value of by-product sintered iron oxide offers a favorable credit to the process and, if pyrites are purchased and processed with the iron sulfate to produce additional acid, the economic picture becomes brighter
Figure 4.
Sintered Iron Oxide
The followirig tabulations of investment and operating costs will give a clearer picture of recovery costs and operations.
Titanium Pigment Waste For a theoretical titanium pigment company having 840 tons of waste liquor per 24 hours of operation Table I would apply. This table shows that the profit is substantial and even without considering disposal costs, the write-off period is very short.
Steel Mill Liquor As another example let us select waste pickling liquor from a large steel mill buying, daily, 223 tons of sulfuric acid (100% equivalent); 984 tons of pickling liquor are wasted per 24 hours. With analysis as assumed, costs would be as shown in Table 11. Only concentration and filteming of the acid are considered; sulfate is dumped or given to a manufacturer of acid with no credit allowed for the sulfate. In this example no net profit can be shown, but the cost of pickling can be greatly redueed. This is especially true if the plant is located where neutralization of the pickling liquor is
INDUSTRIAL AND ENGINEERING CHEMISTRY
543
Liquid Industrial Wastes Costs of Acid Recovery from Titanium Waste Liquor
Table I.
necessary before dumping. On such a basis, the costs indicate that an investment in a recovery unit would pay for itself in about 19 months.
OPERATINGCONDITIONS PER DAY Analysis, %
Steel Mill Liqaor of High Concentration
Filter Cake, Tons
Heso4
FeSOa HzSOa NzO
25.3 13.4 61.3
FeSOa He0
-
Return Bcid, Tons
Concentrator Feed, Tons
HzSOa 204,4 FeSOa 2.0 H20 133,6 __ Total (60% acid) 340.0 Water Evaporation, Tons
213 113 514 840 Wash water -22 Total feed 866
E2804 FeSO4 Hz0
112.0 8.6 52.4 173.0
-
866
-
(340
+ 173)
= 353
IXCOME A N D EXPENSE P E R DAY Value of recovered products 240 tona 60 acid at 818.00 70 tons 98% acid at $20.00 50 tons calcines a t $5.50 Total
$3672.00 1400,OO 275.00 $5347.00
Operating costs Labor 48 operator hours a t 82.00 96 helper hours a t $1.75 - Svpervision and overhead Hue1 2 1 tons coal a t $10.00 6813 gal. oil a t 7.5 cents Power 13,100 kw.-hr. a t 1 cent
$
96 .OO 168,OO 132 .OO 210.00 611.00 131 .OO
2 000 000 gal. at 1cent/thous.
20.00
illajnteAance, amortization, repairs, taxes 20%/350 days on $1,900,000 1090.00 Profit
2358.00 $2989 00
There are some who advocate the use of stronger solutions for pickling steel, the thought being that there would be less water to evaporate to recover the acid and precipitate from the iron sulfate. To accomplish the same purpose-that is, treat the same amount of steel-one would etpect to have the same quantity of iron sulfate in the pickling solution a t the end of 24 hours. A waste product using higher acid strength in pickling would contain about 25.4% sulfuric acid, 13.4% ferrous sulfate, and 61.2% water. I n this example (Table 111) the plant would start the day with 500 tons of acid (100% equivalent, The quantity of waste liquor would be 1340 instead of 984 tons (Table 11) in order to contain the same amount of iron sulfate as was contained in the liquor of lower concentration. In Table I11 the investment shown is slighdy lower than that in Table I1 because there is less water to evaporate; this is also reflected in the daily operating costs The value of the acid recovered daily cannot be used as a credit since this acid circulates through the recovery system and pickling vats, and a steel company would not use the high strength pickling technique if the waste were to be dumped or neutralized. If a credit were shown. it would represent the same quantity of acid as was used in Table I1 It is obvious that there would be n o advantage in pickling with stronger acid. As a matter of fact, the heavier losses shown with the use of strong acid for pickling would throw the advantage to the low strength pickling technique.
INVESTMENT A X D WRITE-OFP 81,000,000 900,000 $1,900,000
Concenrraring a n i filrerin:! rquipment Roasring and ne\\. acid equy’nent Total investment Write-off:
GCEZE = 340 X 2989
141a
years
Table 11. Costs of Acid Recovery i n a Large Steel Mill OPERATINGCONDITIONS PER DAY Analysis, %
Small Steel Mill This is a theoretical case of a relatively small steel mill that purchases 50 tons of acid (100% H2S04) per day and is in a location where it is necessary t o neutralize the waste before dumping
Table 111. Costs of Acid Recovery i n a Steel Mill Using Concentrated Acid OPERATING CONDITIONS PER DAY
Filter Cake, Tons
HzSOI
FeSO4 HzsOa
8.5 18.3 73.2
FeSO4
Hz0
FeSOd
Wash water T o t a l feed
Return Acid, Tons &SO4 FeSOl
83.6 180.0 720.4 984.0
-
Hz0
-
Hz0
Concentrator Feed (Loss lo%), Tons
H&Oa
178.0 13.7 82.3 274.0
69.9 1 0 45.6 __ 116 5
Hz0 Total (60% acid) Water Evaporation, Tons
40 1024
1024
- (274 f 116.5)
= 633.5
Analysis, % HzSOa FeSO4
HzO
Concentrator Feed (Loss HzS04 340 FeSOa 180 HzO 820 Wash water Total feed
INCOXE A K D EXPENSE PER DAY Acid costs without recovery 223 tons at $18.00 Neutralization cost if reqd. Acid costs with recovery of 69.9 tons Labor 24 operator hours a t $2.00 8 48 00 48 helper hours a t $1.75 84 00 Supervision a n d overhead 66 00 Fuel 12,235 gal. oil a t 7.5 cents 918 .OO Power 17,125 kw.-hr. at 1 cent 171.00 Water 233,000 gal. at 1 cent/thous. 3 00 Maintenance, amortization, repairs, taxes 20%/350 on 1,700,000 971.00 New acid purchased, 153 tons a t $18.00 Savings on recovery operations
Write-off:
5 44
concentrating and filtering equipment ~5~~~~
X 12
-
19 months
178.0 13.7
lo%), Tons
1340
4
0 1380
82.3 274.0
Return Acid, Tons
HzSOr
325 4 211
FeSOa
Ha0
Total (60% acid) ‘3 Water Evaporation, Tons 1380
- (274 + 540)
= 566
INCOME AND EXPENSE PER DAY $4014.00 4014.00
$226 1 .00 2754.00
$8028 00
-5015 00 $3013 .OO
Acid costs without recovery 223 tons a t $18.00 Neutralization coat if reqd. Acid costs with recovery of 325 tons Labor 24 operator hours at $2.00 S 48.00 48 helper hours a t $1.75 84.00 Supervision a n d overhead 66.00 Fuel10,924 gal. oil a t 7.5 cents 819.00 Power 153.00 15,290 kw.-hr. a t 1 cent Water 1,100,000 gal. a t 1 cent/thous. 11.00 Maintenance, amortization, repairs, taxes 20%/350 on $1,600,000 915.00 New acid purchased, 175 tons at $18.00 Savings on recovery operations
INVESTMENT A N D W‘RITE-OFF Investment:
Filter Cake, Tons 25.4 13.4 61.2
S4014.00 4014.00
S8028.00
$2096.00 3150.00
5246.00 -~ S2782.00
INVESTMENT A N D WRITE-OFF $1,700,000
Investment: Write-off:
concentrating and filtering equipment
$1,600,000
1,600,000 350 2782 X 12 = 20 months
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 3
-Liquid Table IV.
Costs of Acid Recovery in a Small Steel Mill
Analysis, %
OPERATINQ CONDITIONS PER DAY Filter Cake, Tons FeSO4 33.0 8.5 His04 1.5 18.3 HzO 15.5 73.2
50.0
Concentrator Feed (Loss 25%), Tons HZsO4 15.5 FeSO4 33.5
Return Acid, Tons His04 14.0 FeSOa 0.5
Wash water Total feed
Total 23.0 Water Evaporation, Tons 191 (50 i23) 118
Ha0
__ 8.6
Ha0
134.0 183.0 8.0 191.0
-
INCOME AND EXPENSE PER DAY Aoid costa without recovery 60 tons a t $18.00 $ 900.00 Neutralization cost if reqd. 900.00 $1800.00 Aoid costs with recovery of 50 tons (total daily requirement) Labor 48 operator hours a t $2.00 $ Q6.00 126.00 72 helper hours a t $1.76 Sunervision and overhead 111.00 FuelCoal 3.5 tons a t $10.00 36.00 Oil, i280 gal. a t 7.5 cents 171.00 Raw materials Filter cake, 50 tons Pyrites 14.5 tons a t $10.00 145 00 Power 7600 kw.-hr. a t 1 cent 76 00 Water: I,IOO,OOOgal. a t 1cent/ 11 00 thous. Maintenance, amortization, repairs, taxes, 20%/350 on
-
1,080,000
670.00
Less value of caloines, 15 tons a t $5.50
$1451 .OO 82.00
Savings on recovery operations
INVESTMENT A N D WRITE-OFF Investment Concentrating and filtering equipment for recovery 14 tons HzS04 (60%)
Roasting and acid producing equipment for production 36 tons HzSOr (98%)
Total
$
1369.00 I 431.00
330,000
750,000 $1,080,000
Industrial Wmtes-
and where acid is expensive or difficult to obtain (Table IV). The acid is concentrated to 60% to remove the iron salts and is returned to the pickling vats. The sulfate is roasted with the addition of pyrites to produce fresh acid in sufficient quantity to meet the needs of the mill. In Table IV no net profit can be shown since the value of the products is less than the total daily cost of recovering them. There is a saving in pickling costs but the investment write-off is rather slow.
Summary Many other examples could be set up since pickling procedures differ widely and local conditions vary. Because of the high investment required and the cost of fuel for water evaporation, it is difficult to show a favorable return on a steel mill pickle liquor recovery plant. Acid pickling is a minor item of cost on the steel manufacturer’s books, and he will probably continue to dump his waste as long as he is able to purchase fresh acid a t reasonable cost and is not prevented from dumping it. A shortage of acid and restrictions against dumping it would alter the situation. The recovery situation is somewhat different as it applies to titanium pigment manufacturers The by-product from this industry is in such form that recovery is ecoaomically feasible. Some objections have been raised by pigment manufacturers who state that the acid recovered by concentration carries impurities that would contaminate the pigment if the acid were re-used. However, there would be a ready market for the recovered acid in other industries and roasted sulfate would produce an acid of a purity suitable for any purpose. The process described can not be utilized economically in all cases, but i t is a practical one and can be applied when a scarcity of raw materials or other attending circumstances make it advisable.
1 080 000 = 7 years, 2 months Write-off: 350 X 431 RECEIVED for review September 6, 1951.
ACCEPTED December 17, 18.51.
WASTES CONTAINING RADIOACTIVE ISOTOPES C. C. RUCHHOFT, Public Health Service, CincZnnati 2, Ohlo A. E. GORMAN, Atomic E n e r g g Commission, Washington, D. C. C. W. CHRISTENSON, Atom& Energg Commission, Los Alamos, N . Mex. Coagulation and carrier precipitation procedures common to municipal water purification practice have been applied to the treatment of low level radioactive wastes containing plutonium. A chemical coagulation and filtration plant was designed and built at Los Alamos, N. Mex., following laboratory studies on the treatment of research laboratory wastes. The objfctive of the waste treatment was to reduce the plutonium content to that permissible
in drinking water. The features of the design and operation of the plant are described. Operating results to date indicate that the plutonium removal objective has been attained. The treatment costs about 0.8 cent per gallon of waste. Biological treatment has also been applied to some wastes that cannot be treated by chemical precipitation because of interference due to sequestering agents and detergents.
H
It is probable that no new industry has given such serious consideration to its waste disposal problems in the interest of the public welfare than has the American atomic energy industry. Realization within this industry of the environmental aspects of waste disposal as well as its economic significance is a most important consideration and is setting a good example for all new industries. In sharp contrast with wastes of other industries, radioactive wastes may not be objectionable as measured by such common
AYNER ( 4 ) discusses the policy of the Atomic Energy
Commission with respect to many problems on the treatment and disposal of high level radioactive wastes. Gorman (3)has presented a discussion of the sanitary engineering approach to the waste disposal problems of the industry. He points out that the effectiveness and economy of the recommended procedures have found wide acceptance by American industrial management and refers to research in progress supported by the Atomic Energy Commission.
March 1952
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