ANTIBIOTICS J. 31. BROWA‘ and J. 6. NIEDERCORN, LederZe Laboratories DZvZxion. American Cyanamid Co., Pearl River, N . 1’.
w a s t e s from the manufacture of antibiotics present a new and, in some respects, a difficult disposal problem, partly because of the presence of antibiotic substances and also because of unusually large quantities of organic matter. Publications up to this time have been confined to the treatment of penicillin, streptomycin, and aureomycin wastes. The relative merits of both laboratory and plant treatments are here discussed, with the inclusion of unpublished data concerning the disposal of aureomycin wastes. Some products of value as supplements to animal
feeds have been obtained as by-products, but much more might be accomplished in this direction. The propertics of the material sometimes make it possible to turn the wastes to some use, but often they make even ordinary methods of disposal more difficult. Thus, the rcsidual antibiotics may result in the loss of desirable flora in both beds and aeration tanks, malting i t necessary to proceed. with new and untried organisms, which may cause unforeseen difficulties. The biological processes are fairly successful; many- phenomena remain to be explained.
S
HORTLY after its discovery, the manufacture of penicillin is uneconomical, as well as st,ill residues resulting from solvent was undertaken b y a nuniber of industrial organizations recovery operations. whose experience with large scale fermentation processes varied 4. Barometric condenser waters from evaporation and drygreatly; those having had no previous experience found theming processes are generally very dilute and ma): contain volatile selves confronted wit,h the unfamiliar problem of disposing of large and entrained nonvolatile organic matter. I n the manufacture quantities of relatively concentrated liquid wastes resulting from of aureomycin such wat,ers have shown biochemical oxygen dethe manufacturing processes. This problem was often doubly mand values of 60 to 120 p.p.m.; their t’emperatures varied beurgent and exacting because of unfavorable plant location or some tween 100‘ and 108’ F. Chlorination t o the break point and ot.her factor not, requiring consideration originally in the selection lagooning for 10 hours reduced the biochemical oxygen demand of their plant sites, because the projected operations did not in10 t o 20oj, and resulted in considerable cooling. Ordinarily the liquids requiring disposal consist of mixtures of clude fermentation processes at,that time. Since t,hen penicillin beers, wash waters, and chemical wastes, but in a t least one inhas been supplemented by other antibiotics, each of which has stance penicillin beers only were concentrated under vacuum and brought, problems of its own, some of which require special conspray dried (10). The resultant product was mixed with dried sideration, but in general certain broad principles appear to be applicable to all. ground mycelium and used as a source of vitamins for anirnal feeds. Subsequently the process proved unsuccessful in the T h e wastes resulting from the manufacture of antibiotics may treatment of aureomycin broths, because of their greater dilution be classified as solids and liquids. and sensitivity t o heat. Solids. This class consists of filter cakes containing filter aids-usually diatomaceous earth or active carbon-together I n laboratory experiments conducted under the direction of with mycelium. These may be incinerated, buried, or dried; the Mohlman ( 7 ) the best results with trickling filters were obtained dried and ground cake may be suitable for fortifying animal feeds. b y aerat.ion for 4 hours and dilution vith four parts of water before application t o the filter, giving a removal of 96% with singleLiquids. 1. Spent st,rong fermentation broths are often called “beers.” The): may be clear because of recent filtration, stage application a t t’herate of 1450 pounds per acre-foot per day. -4naerobic digestion was unsuccessful. in which event the biochemical oxygen demand may vary from A plant designed for the treatment of penicillin and strepto4000 t o 13,000 p.p.m. if they are penicillin wastes; streptomycin mycin wastes has been described by Hilgart ( 7 ) . The mixture of spent broths average approximately 2500 p.p.m., and aureomycin broths range from 4000 to 7000 p.p.m. An occasional spoiled wast,es and Tvash water is aerated 10 hours in holding t,:inks, batch of penicillin broth containing mycelium may approach 20,000 p.p m. (Biochemical oxygen demand ip to be I construed as the 5-day biochemical 90 2 oxygen d e m a n d t h r o u g h o u t t h i s g 80 l..-..-
-
1
,.---:
-Liquid settled 2 hours, diluted and passed through two trickling filters either parallel or in series, again settled 2 hours, and finally chlorinated. The sludge is digested anaerobically and dried in open beds. The two holding tanks have a capacity of 25,000 gallons each, the circular trickling filters are 90 feet in diameter and 6 feet deep (the size of the stone is not specified). Recirculation of the underflow from the h a 1 sedimentation tank or of cooling water provides a constant flow of 700,000 gallons per day through the plant which was designed to treat 3060 pounds of 5-day biochemical oxygen demand per day. Sludge digestion involved some difficulties originally, inasmuch as the contents of the digester became acid, but eventually its operation became satisfactory in this respect. However, diatomaceous earth contained in the sludge threatened to cause serious loss of digester capacity due t o compacting. At times the filter stones became coated with oil, which was attributed to the use of lard oil as a n antifoaming agent in the fermentation, but the coating sloughed off during periods of light loadings. I n the beginning, the incombustible gases from the digester had an objectionable odor; they were enriched with propane and burned. Objectionable odors from the sludge beds were overcome by spraying with o-dichlorobenzene. Hilgart concluded that these wastes can be treated successfully by biological processes inasmuch as in the operation of the plant, biochemical oxygen demand removal was as high as 97%, and the total biochemical oxygen demand discharged to the stream was less than 60 pounds per day. Extensive pilot plant work on penicillin wastes has been reported b y Muss (12). Biochemical oxygen demand reductions of 82% were obtained using shallow filters a t recirculation ratios of 15 to 1 with loadings of 3 pounds of biochemical oxygen demand per cubic yard of stone, and efficiencies of 97% were obtained with deep filters a t 0.2 pound of biochemical oxygen demand per cubic yard of stone, However, during the winter months the reductions were only 42 and 57%, respectively, other conditions remaining the same. This was attributed to excessive cooling a t the high recirculation rates used. Anaerobic digestion of the wastes appeared feasible but was believed economically unsound; aeration in the presence of dispersed growths reduced the biochemical oxygen demand 85% or more. Digestion of the sludge from any of these processes proceeded rapidly a t 75" F. when seeded with digested sludge. Biological treatment removed little of the 2000 p.p.m. color in the initial waste; the use of 1000 p.p.m. of chlorine resulted in the removal of 95% of the color. Muss (12) concluded that the use of shallow trickling filters followed by deep trickling filtration offered a n economical method of treatment; low rates of filtration resulted in the removal of better than 90% of the biochemical oxygen demand. When only partial treatment is required short-period aeration is recommended. The disposal of liquid wastes from the manufacture of aureomycin has been described by Brown ( 2 ) . The treatment consists of storage, grease removal, 4l/2 hours of aeration, 5 t o 1 dilution with filter effluent, sedimentation, and application to three highrate trickling filters, followed by h a 1 sedimentation and chlorination. The effluent is sent to the Pearl River municipal sewage disposal plant together with certain weaker wastes which are bypassed; on the way both are diluted with domestic sewage from Pearl River. The volume of Mstes given this preliminary treatment is approximately 400,000 gallons per day and a like quantity is by-passed. This amounts to 60% of the volume treated at the municipal plant. The aeration tank is 12 feet deep and is equipped with saran Chicago Swing diffusers delivering 1.5 cubic feet of air per gallon per hour; the three $@foot clarifiers have a %foot side water depth and provide 1.5 hours detention time a t a 5 to 1 recircula-
March 1952
IndustrialWastes-
tion rate. The sludge is dewatered on a rotary vacuum filter and incinerated or buried; this operation is possible without chemical treatment because of the sludge's high content of diatomaceous earth, which constitutes 60 t o 70% of its solids. The three high-rate trickling filters are 100 feet in diameter and 6 feet deep. The stone consists of 21/2- to 3l/2-inch trap rock laid without a n outside supporting wall, allowing the stone t o assume its natural slope.
Table I.
Date, 1948
8/25 8/27 9/1 9/3
%E 9/10 9/15 9/22 10/20 10/22 10/27 10/29 10/31 11/3 11/10 11/12 11/15 11/18 11/20
Pilot Filter Performance Data
Biochemical Oxygen Demand Raw Final
2150 2500 2600 2500 2700 2150 2200 1520 2000 1750 600 750 575 700 400 1000 500 480 680 580
680 725 1400 1900 1800 940 1000 680 1000 900 240 300 270 415 180 450 230 220 280 240
Reduc-
tion, % 68.5 71.0 46.4 24.0 33.3 56.4 54.5 55.3 50.0 48.6 60.0 60.0 53.0 40.7 55.0 55.0 54.0 54.2 58.8 58.7
Filter Loadings, Lb. Biochemical Oxypn Deman /Acre Foot/Day
12,000 12,000 14,000 12,000 14,000 11,400 10,800 10,800 12,000 15,000 18,000 18,000 18,750 14,000 8,000 8,500 7 200 7:200 7 200 7 500
:
Recirculation Rate
8-1 8-1 4.3-1 1.5-1 1.3-1 4-1 4-1 3-1 3-1 4-1 4-1 4-1 4-1 2-1 4-1 3-1 4-1 4-1 4-1 4-1
Prior to the construction of the trickling filters, a small filter 6 feet in diameter and 3 feet deep composed of 21/2- to 31/2-inch trap rock was operated a t loadings up t o 18,750 pounds of biochemical oxygen demand per acre-foot, or 11.6 pounds of biochemical oxygen demand per cubic yard of stone with a reduction of 53y0, Filter efficiencies of 50 to 60% were observed over a wide range of loadings. Table I contains some of t h e data obtained. Table I1 contains one year's operating data from the plant before the third filter went into service. The figures are averages of 12 to 15 determinations of the 5-day biochemical oxygen demand made duSing the month. Figure 1shows graphically the per cent of biochemical oxygen demand reduction, filter loadings in pounds of biochemical oxygen demand per acre-foot, and biochemical oxygen demand removed in pounds per acre-foot. During the first month of operation (July 1949), filter reductions of over 80% were accomplished at loadings of 3350 pounds of biochemical oxygen demand per acre-foot. As the filter loadings increased and the weather became colder in succeeding months, the per cent reduction fell to half its former value, but the pounds of biochemical oxygen demand removed per acre-foot of stone changed relatively little. T h e maximum loadings occurred in April 1950 averaging 7350 pounds of biochemical oxygen demand per acrefoot or 4.6 pounds per cubic yard of stone. During the spring of 1950 the per cent reduction rose t o over 6OY0, indicating that the cold weather drop in filter efficiencies in t h e treatment of aureomycin wastes had been higher than that expected for domestic sewage. The same cycle was repeated the following year. The pounds of biochemical oxygen demand removed per acre-foot varied directly with the filter loadings, but the variations wcre less extreme. During the winter of 1950-51 one of the filters showed evidence of ponding, resulting from the interstices becoming filled with a black mud evolving considerable hydrogen sulfide. The mud could be resuspended in water without difficulty, but when undisturbed on the filter bed it seemed t o form a water-impervious layer. A sample contained 69.5% moisture; on a moisture-free basis the chemical analysis was as follows:
IN D U S'T R IA L A N D E N G IN E E R I N G C H E M I S T R Y
469
'
L i q u i d Industrial Waste% Ash Silicon dioxide Metals pptd. by ammonia Calcium i'+&mmium
The high sulfur content (approximately 1.5% of sulfur on the basis of the original chloroform-soluble material) is worthy of note; it suggests that the sulfur may have been EL part of an organic compound. The crude chloroform extract dissolved almost instantly in hot 0.1 N sodium hydroxide a t temperatures above its melting point, and remained in solution upon subsequent cooling to room temperature. However, attempts to dissolve it a t temperatures below its melting point were unsuccessful. Apparently, to rid a filter of this material would require heating the entire bed to 150' F. or higher.
69.8 54.8
15.4 0.7 0.3 1.6 9.5
Chloroform extract Sodium Potassium
0.7
None
Organic m a t t e r other t h a n crude fat, by difference 20.6 Diatomaceous earth, calcd. from silicon dioxide 69 Alkalinity of ash 0.8 mi. of 0.1 A' HCl/g. of ash
Apparently these solids consisted of approximately 70% diatomaceous earth and 30% organic matter, one third of the latter being soluble in chloroform. .1 large sample, 16 grams, of the chloroform-soluble material was prepared by extracting the dried mud and was found to be an extremely viscous tacky brown material melting a t 64' C. and having the following composition: M a t t e r volatilized a t 10.5' C. in 4 hours Ash Total nitrogen, Kjeldahl Unsaponifiable m a t t e r Kitrogen in unsaponifiable m a t t e r Insoluble f a t t y acids
4.3 10 6 0.92 29.4 0.08 37.0
Rlg. KOH/Gm. 22.9 290.6 273.3
Acid value of original material Saponifiration value Seutralization value of insoluble f a t t y acids 3Ienn molecular weight of insoluble f a t t y acids
Figure 2.
205
Analysis of .4sh
These hidings lead to the suspicion that ponding in cold weather is sometimes aided by factors other than the more luxuriant growth of fungi, especially in beds containing coarse stone. An examination of the ponded areas disclosed further that some of the stones had a diameter of less than 1 * / 2 inches, which was thought to contribute to the ponding, and, therefore, when the third filter was built, its stone was screened a t the filter site, using a rotating cylindrical screen mounted on a converted concrete transit mix truck. The stone was placed on the under-drains by means of conveyors. Figure 2 shows the screen in operation and Figure 3 shows a completed bed. The organisms observed on the stones of the filters over a period of six months were as follows (4):
% Ferric oxide 0.96 Magnesium 1.89 1.83 Phosphate Silicon dioxide 2.65 46.2 Sulfate Calcium 16.7 15.0 Sodium 2.5 Potassium Alkalinity of ash = 101.9 ml. of 0.1 A' HCl/g. of ash
The large quantities of iron, calcium, and sodium suggested the presence of salts of high molecular weight organic acids; the surprisingly high iron content may have been due to a complex conipound of the type often formed by organic acids. The mean molecular weight of the insoluble fatty acids approximated that of lauric acid; about 23% of the chloroform-soluble material was soluble in water after saponification and could not be recovered by extraction.
Table 11. July
Fungi. Geotrichum candidum, Fusarium episphaeria ( F . aquaeductum), and a dematius fungus. Algae. Chlorella sp. Bacteria. Large ovoid cells with brick-red pigment in the cytoplasm, cocci, rods, spirilla, and chains of small cylindrical cells.
Plant Operating Data
1950 Aug. Sept. Oct.
Screening of Filter Stone and Placing on Filter
Nov.
Dee.
Jan.
Feb.
1951 l._.ll Mar. Apr. May
June
Storage Biochemical oxygen demand 1675 2130 2529 2320 2830 2330 2910 Suspendedsolids 1124 1340 2050 1543 1212 1910 2070 Organic nitrogen 31 37 32 31 27 22 29 79 80 98 85 93 Total nitrogen 142 98
3820 3124 2620 2350 2850 2618 1664 2012 2180 2050 50 30 22 32 29 112 123 92 116 102
d e r a t i o n Effluent Biochemical oxygen demand 1476 Suspendedsolids ... Organicnitrogen , ,. Total nitrogen ..
1700
.
... .,. ,..
1800
2480 44 97
1681 1460 44
1910 1890 2120 3140 2750 1465 1370 1567 1541 1572 21 23 22 23 26 100 69 70 70 82 88
665 176 15 49
910 228 23 65
668 293 20 60
796 256 17 70
,..
536 384 41
190 114 8 49
306 187 14
2410 1710 1724 2080 22 29 112 102
1990 1350 57 143
Filter I Biochemical oxygen deinand Suspended solids Organicnitrogen Total nitrogen -
1100 278 29 105
1190 377 20 79
1550 2010 445 262 21 25 80 78
1301 1030 380 28 68
304 29 115
677 272 23 112
910 257 40 84
1762
1400 214 26 114
738 322 23 117
886
Filter 11 Biochemical demand oxygen Suspended solids Oiganicnitrogen Total nitrogen
470
. I ,
88
67
1180
932
156 21 80
422 19 75
284 19 86
17,5 278 23 81
443 19
23
353 33 91
I n addition there were yeastlike cells, diptera larvae (probably psychoda), nematodes, ciliates, and paramecia. Of these the fungi, algae, red bacteria, and yeastlike cells were most abundant. Several manufacturers of penicillin discharge penicillin wastes directly to m u n i c i p a 1 s e w a g e d is p os a 1 plants. Mann (11 ) reported the sterilization of a sludge ~- digester by toxic substances inadvertpntly discharged to the sewer by a plant manufacturing penicillin. Such a possibility makes anaerobic fermentations of antibiotic wastes less attractive, inasmuch as the quantities of materials affected would be very much larger than in an aerobic process of similar capacity.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 3
-Liquid
IndrcetrZal Wamk-
T h e plants described are conventional in design, probably befermentation employed seemed likely t o prove useful in the treatment of filtered spent aureomycin broths. Moreover, the cause of the urgent necessity of placing them in operation organism grew well in t h e presence of as much as 10 p.p.m. of promptly, and t h e paucity of experimental data. The fears that aureomycin, and several preliminary tests had shown that freshly the presence of antibiotics in t h e wastes would affect their perfiltered spent broth did not require sterilization or even pasteurformance adversely proved groundless, probably because the antiization for a successful fermentation. biotics are not affective against all organisms, and therefore merely exert a selective action on the microorganisms introduced. Fortunately the number of resistant varieties seems t o be large enough to meet all needs. Significant departures from past practice have been suggested by Weukelekian (b), who has shown that in t h e laboratory t h e aeration of strong antibiotic wastes having a biochemical oxygen demand of 3800 p.p.m. produces nonflocculent growths with a 70% biochemical oxygen demand reduction in 24 hours, using 2.0 cubic feet of air per gallon per hour; in 6 hours the reduction was approximately 40%. Heukelekian found no difference in the properties of penicillinand streptomycin-spent broths, except that the latter were less concentrated. H e found that the quantity of seed added could be varied within wide limits without impairing biochemical oxygen demand reductions, and that new seed could be obtained from soil with little difficulty. Penicillin wash water was qualitatively very similar to t h e spent broth. Both required more Figure 3. Trickling Filter and Clarifier air per pound of biochemical oxygen demand removed by dispersed growth than is commonly used in the activated sludge process, but since no sludge was formed, the reduction in biochemical oxygen demand was assumed to represent complete oxidation. A continuous fermentation was carried out (1) in a 50-gallon The apparatus used consisted of cylindrical glass tubes 2.5 experimental fermentation tank equipped with a ring sparger inches in diameter and 24 inches high. Air was supplied to a with fifty 0.0312-inch holes and a stirrer such as described b y diffuser bulb attached to t h e rubber stopper closing t h e bottom of Inskeep et al. (8). The tank was charged with 76 liters of spent the tube. aureomycin broth, and after the addition of 0.3% each of amI n another series of experiments (6) small-scale anaerobic fermonium sulfate and monopotassium phosphate, it was sterilized mentations of penicillin and streptomycin wastes were conducted a t 120' C. for 20 minutes, cooled t o 26' C. and inoculated with in the laboratory. T h e types of wastes treated included penitwo 12-liter bottles of a 24hour culture of ToruZop,sis utilis. cillin-stripped spent lactose broth, penicillin wash water, peniThe rate of stirring was 140 r.p.m. and sterile air was supplied a t cillin composite, penicillin-stripped spent brown sugar broth, and the rate of 8 cubic feet per gallon per hour. (It was later found strJptomycin meat broth. These originated in two different that 2 cubic feet per gallon per hour was ample.) The temperaplants and varied from 825 t o 10,000 p.p.m. of biochemical oxyture was maintained at 26" to 28' C. During the first 24 hours gen demand, It was found that solvents contributed appreciably of the fermentation, no further additions of waste were made in to the biochemical oxygen demand, and t h e manner in which cerorder to build up the yeast population. tain solvents affect the biochemical oxygen demand determination is discussed. 7.0 Anaerobic digestion was facilitated by gently dl. Effl. Infl. Effl. InfL Effie stirring t h e contents of the digester; under OOQ 6Qoo BOD Wao 5403 7600 5500 .t optimum conditions (daily dosage of 5% of WuMW *.O*I. the volume) there was a n 80% reduction in 8.0 biochemical oxygen demand with the evolution of 2 to 2.5 volumes of gas per volume of waste ,-*, i' 'I fed. The sludge formed was estimated t o cons.0 ll I tain approximately 11.5 pounds of solids per \ ,*--.-/. 1000 gallons of waste. I I I Heukelekian found that ordinary sedimentaI I 4.0 tion and chemical treatments did not reduce '\ / ', the biochemical oxygen demand of the untreated 8. 4 wastes. H e recommended treatment by an3.0 aerobic digestion or aeration, followed in either call v o l u m c l -.-.-.-.-.case by coarse- and fine-grained filtration; -.-.-.-.-.effluents having a biochemical oxygen demand of 35 t o 40 p.p.m. should be obtainable in this 2.0 manner if the rates of filtration are low enough.
--
-
$
2
-
-
Continuous Yeast Fermentation T h e press juice obtained in the manufacture of dried pulp from citrus peel (IS) and waste liquors from the isolation of protein from peanut meal (9)have been utilized in the cultivation of the yeast Torulopsis utilis. T h e continuous
March 1952
to*
I
I
I
I
1
3
5
4
Figure 4.
J s
I
II
I
6 7 e D A Y S ----+
I l l e io
I
I
11
12
I 1s
Torulopsis utilis Continuous Fermentation in Aureomycin Spent Broth 50-gallon aerated tank Dotted line. pH Solid line. Reducing substances as glucose. mg. per ml.
INDUSTRIAL AND E N G I N E E R I N G C H E M I S T R Y
471
Liquid Industrial Wastes Since it was difficult to obtain small quantities of filtrate from plant operations, 350 gallons of filtrate were run into a 500-gallon tank, and, after the addition of salts and sterilization as above, were held to provide the feed for the fermenter. At the end of 24 hours, 12l/2 liters of the fermenting wastes were uithdmwn from the 50-gallon tank; a like quantity of sterile waste was withdrawn into buckets from the holding tank and added t o the fermenter through the open manhole. This process was repeated every half hour thereafter and no precautions were taken to prevent contamination. Every 2 hours the fermented liquor withdrawn was sampled; 10-ml. aliquot8 were centrifuged for 15 minutes, the cell volume was read, and the supernatant liquid was analyzed for reducing sugars as glucose by the method of Hagedorn and Jensen ( 3 ) . Figure 4 shows the results of the experiment graphically. The cell volumes for each batch of filtrate were averaged; the other curves were obtained by drawing a smooth line through the points representing the 2-hour samples. Apparently, when sufficient sugar was present, the pH tended to remain low, and in all except the third batch of filtrate, the cell volume varied directly with the sugar content of the untreated waste. I n the fourth batch the glucose reduction was less complete than in the others, and in all batches for which it m-as determined, the residual biochemical oxygen demand was between 5400 and 6000 p.p.m.
This experiment demonstrated that under proper condition8 the fermentation could be carried on uninterruptedly for long periods of time, and that the sugars could be reduced 80 to 90% with a 4-hour holdup.
Literatnre Cited ( I ) Ball, E. L., private communication. (2) Brown, J. M., Sewage and Ind. Wastes, 23, 1017-24 (1951). (3) Hagedorn, H. C., and Jensen, B. K.,Biochem. Z . , 135,46 (1923); 137, 92 (1923). (4) Hesseltine, C. W., piivate communication. (5) Heukelekian, H., ISD. ENG.CHEaf., 41, 1412-15 (1949). ( 6 ) Ibid., PP. 1535-9. (7) Hilgart, A . A., Sewage and Ind. Wastes, 22, 207-11 (1950). (8) Inskeep, G. C., Bennett, R. E., Dudley, J. F., and Bhepard, M. TI'., IXD.ENG.CHEM.,43, 1488-98 (1951). (9) Klatt, T. J., Parker, E. D., Pomes, -4.F., and Porges, N., Oil & Soap, 22, 319-21 (1945). (10) Knoedler, E. L., and Babcock, S. €I., Jr., IND. ENG.CHEM..,39, 578-82 (1947). (11) Mann, V. T., private communication. (12) Muss, D. L., Sewage and Ind. Wastes, 23,486-96 (1951). (13) Veldhuis, 11 K., and Gordon, W.O., CztrzcsInd., 29, 7-9 (1948).
RECEIVED for review September 17, lY5l.
ACCEPTEDJ a n u a r y 11, l Y 5 2 .
ATOMIC ENERGY INDUSTRY J. € HAYXER, I . U . S. Atomic Energg Commission, Washington 25, D. C.
T h i s paper describes planned programs of research and development bearing on handling of waste products by the nuclear energy industry. There are several reasons for such a program: The products have a high hazard POtential; the industry has grown at a phenomenal rate from laboratory scale processes to plants of major industrial size; security restrictions have prevented supervision
by public agencies; and substantial expansion of the industry into new and broader fields is contemplated with increased problems of disposal and environmental hazards. This paper classifies the sources of radioactive wastes, describes methods of waste treatment, and defines limitations and tolerances for radioactive wastes. Public health and environmental aspects of atomic energy are discussed.
T
essing and disposal and environmental hazards are most important in the interest of national health and security. The need for appraisal of the waste problem was recognized by the Division of Engineering, Atomic Energy Commission, when in the summer of 1948 it appointed a panel of experts t o examine the various chemical operations with attendant waste streams and t o recommend a program of research and development which would be directed toward corrective treatments. This committee, consisting of representatives from Xonsanto and Doiv Chemical companies and the Argonne h'ational Laboratory, returned a report, which clearly defined the sources of liquid radioactive waste streams and recommended broad avenues of investigation. In the main, these recommendations have been followed, the details of which will be discussed later in this paper.
HE development of atomic energy has brought with it the inherent disagreeable and hazardous problem of disposing of the many heretofore practically useless radioactive by-products. Because of the known physiological factors, it is clear that any commercial application of atomic energy, its development as a power source, and the advancement of the science in general will be dependent on the development of satisfactory, safe, and economical methods of controlled disposal. It is a sound policy for any new industry to appraise its operations and planned programs of research and development from the viewpoint of the characteristics of the waste products it may produce and any environmental hazards it may create. This is especially true in the newest of all industries: the utilization of atomic energy. Several reasons emphasized this need: (1) The products, because of the presence of radioactivity and to a lesser extent, toxicity, have a high hazard potential; (2) under wartime urgency, research and development were accelerated a t a phenomenal rate from laboratory investigation, through pilot models, to plants or major industrial size; (3) security restrictions have insulated this industry from the customary observation and supervision by public agencies; and (4) Steps are being taken which may lead t o expansion of the industry into new and broader fields where consideration of waste proc472
Types and Sources of Radioactive Wastes The sources of liquid wastes which must be given special handling t o ensure safety are:
1. The production phases of the national atomic energy program-namely, the huge chemical separation plants and nuclear reactors. 2. The laboratories and hospitals where radioactive materials are used as research tools and/or for medical treatment.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 3
