TNT Wastes from Shell-Loading Plants COLOR REACTIONS AND DISPOSAL PROCEDURES C. C. RUCHHOl?I', M. LEBOSQUET, JR., A N D WILLIAM G. MECKLER U. S. Plcblic Health Service, Cincinnati 2, Ohio This study was made to assist in solving the problem of the disposal of liquid wastes from TNT bomb- and shell-loading plants. The factors affecting the conversion of alphaTNT in these wastes to a colored derivative were studied! it was found that natural degradation of TNT was too slow for application to the treatment of wastes. Small quan-
A
tities of both forms of TNT reduce the rate of biochemical oxidation in polluted waters without reduction of TNT. Interference with biological treatment prevents treatment with domestic sewage. Soil absorption and activated carbon treatment were the most promising procedures studied for the removal of TNT from these wastes.
theless, the previous paper on T N T wastes (3)from manufacture indicated the stability of the nitrotoluenes and some of the difficulties of treatment. The present study was made to assist in the trinitrotoluene) waste waters arose. These waste waters are safe and economical disposal of T N T wastes from loading plants. produced when the kettles for melting T N T are washed out and thoroughly cleaned with steam and water. The water solution The fact that T N T waste in the drainage ditches at shellloading plants was red while fresh T N T solutions are uncolored of the T N T is collected in a concrete tank where most of the T N T suggested that the waste was reacting or decomposing. An crystallizes out and can be removed. However, the overflow experiment with uncolored T N T was therefore started. Dufrom these tanks, in most cases, is allowed to flow through open plicate portions of tap water ( A ) , polluted water (75% tap 25% drainage ditches to the nearest creek or stream. The pollution sewage plant effluent) ( B ) , and activated sludge plant ehuent (C) were dosed so that they all contained 26 p.p.m. of TNT. from T N T in the ditches and very small streams is evidenced by One set of samples waa held in the dark, and the other in direct the dark red color of the water. sunlight as lon as possible each day. During an inspection at several of these plants, the opinion Samples A , and C, held in the dark at 20' C., showed no was expressed by those in authority that the T N T in aqueous r p t i b l e change in T N T concentration during an 80-day period y the spectrophotometric method for a-TNT and colored solution was decomposed and destroyed by two reactions in the T N T (2). The maximum extinction values observed on direct water. The first method of destruction suggested was photoexamination during the 80-day period were 0.14 for A and B chemical and chemical reaction induced by the sun; the second and 0.35 for C. I n other words, the slight trace of color formed was biochemical. No evidence was submitted, however, that in the dark gave practically no indication that T N T was present. It was concluded that, in the dark, T N T in polluted water solueither of these reactions was effective. It was also suggested that tions was not altered infiltration into soil materially in 80 days at would effectively reordinary temperatures. move and destroy the The samples exposed I I I I TNT, but again no I I to intermittent sunQ) evidence was available light progressively increased in color, and at to indicate to what exthe end of 80 days had tent this could be deextinctions a t 4 6 0 ~of pended upon. 1.84,2.00,and 1.88 for T h e s e w a s t e s are A , B, and C, respecneutral, contain T N T tively. This color is due to the conversion in concentrations up to of a-TNT to thecolored about 100 p.p.m., and c o m p l e x ( T a b l e I). may have up to 1.0 or These data indicate the 2.0 p.p.m. of nitrotolcourse of the reaction uene sulfonates. in terms of alpha and the combinedor colored Water containing 5 T N T derivative, and p.p.m. of T N T will kill show that a-TNT defish, and is considered creased from 26 to 5-9 unfit for human conp.p.m. and the colored i c sumption. These form increased from 0 Q) i I I I I I I w a s t e s a r e different to 10-11 p.p.m. The 1.0 2.0 3 . 0 4.0 total T N T (sum of both from those from T N T t i Time in Hours forms) decreased manufacture. Neverslowly{ 65 to 75% of 1 Wherever T N T &ment h e original T N T Figure 1. Effect of Carbonate Concentration on Carbonate TNT tioned in this paper, alpha remained after 80 days. Color Development in a Solution Containing 126 P.P.M. of TNT TNT b meant.
T SEVERAL shell- and bomb-loading plants in the United States, the problem of disposing of alpha TNT1 (2,4,6-
8,
1
!+-
I
I -
937
INDUSTRIAL AND ENGINEERING CHEMISTRY
938
Vol. 37, No. 10
some of the pertinent conditions of the last experiment, another TABLEI. ESTIMATES OF ALPHAAND COLORED T N T IN experiment was set up. The data (Table 111) indicate again that SOLUTIONS EXPOSED TO SUNLIGHT AT ROOM TEMPERATURE pH and chemical constituents in the water and li ht conditions Sunlight Colored TNT", Alpha TNTb, Total T N T influence the progressive change in dilute T N T solutionfi. The P.P.M. P.P.M. Remaining, P.P.M. Exposure, alpha T N T was converted to the colored addition product in all D a y a A B C A B C A B C cases, and the rate of this reaction increased with the carbonate 0 2 6 . 1 25.5 26.5 0 0 0 25.2 24.5 25.4 1.7 2.3 2 1.7 concentration and with sunlight. The maximum concentration 2.2 3.7 25.0 21.1 19.4 7 2.3 4.4 19.4 18.8 18.3 3.5 3.7 13 of the colored form was produced after one day in the presence of 20.9 1 8 . 8 16.8 5.2 4.4 4.5 20 1000 p.p.m. of carbonate in this experiment. The rate of re5.9 4.8 2 0 . 0 17.2 14.2 4.1 28 17.2 16.0 14.2 6.0 5.9 35 6.5 duction in total T N T in this experiment was not so great as the 9.1 9.4 14.9 11.8 12.0 49 7.1 5.6 6.7 9.4 80 10.0 11.0 10.7 change from one form to the other. When the experiment was terminated after 36 days, from 53.1 to 73.0% of the original T N T a Based on the color produced on standing and the carbonate TNT com lex extinotion correlation a t 4 6 0 ~ . remained in the various portions, largely as the colored addition b Eased on the net extinction due to sulfite-hydroxide treatment at 505r. product. This demonstrates again that these slow decomposition reactions produced by the concentration of sodium carbonate used here cannot be depended upon as a satisfactory method COLORED TNT COMPLEX IN WATER CONTAINING NORMAL of destroying TNT. CARBONATE
Data on the effect of carbonate concentration, temperature, and light upon the formation of colored T N T derivative are given in Table 11. The term "equivalent extinction" is used for the extinction observed at a dilution multiplied by the dilution factor. Using the maximum extinction values obtained at room temperatures throughout the period of observation as loo%, the percentage color intensities were calculated. These percentages are plotted to show the effects of various factors in Figures 1 , 2 , and 3. Fiyure 1 illustrates the maximum color developed at room temperature in the presence of ordinary daylight (but no direct sunlight) for 5 hours with variations in carbonate concentration; it demonstrates the great importance of carbonate or a similar constituent in the solution for rapid color formation. The four lower curves of Figure 2 show the effect of temperature on color formation in the T X T solution containing 300 p.p.m. of sodium carbonate. Unfortunately the light conditions were not similar for all of these samples. H and I were held in the dark; D,J , K,and M were held in daylight in the laboratory. Even so, the temperature was the most important factor and gave color results increasing with temperature for the first two hours. The lower curve of Figure 3 demonstrates that in the absence of sodium carbonate the effect of sunlight was negligible. With solutions containing 300 and 1000 p.p.m. of sodium carbonate, the curves showing the rate of color formation in sunlight are more erratic and have minor fluctuations due apparently to changes in intensity of sunlight. On the whole, however, these curves follow fairly closely the trend noted in the absence of direct sunlight. The data in Figures 1, 2, and 3 indicate that temperature and chemical constituents of the water and stream bottom are the most important factors involved in the color reaction in T N T solutions and that sunlight is secondary. T o follow the progressive change in dilute T N T solutions under ~
EFFECT O F TNT ON NATURAL BIOCHEMICAL PURIFICATION IN STREAMS
An earlier study (8) showed that wastes from T N T manufacture in considerable concentration had no B.O.D. and adversely affected the B.O.D. reaction. These earlier data were obtained by crude methods before the method for determining T N T concentration and B.O.D. reaction separately had been devised Consequently, a number of experiments were performed on sewage dilutions to determine the extent of the interference of small quantities of T N T on the natural biochemical oxidation of organic matter. Table I V lists the data obtained in one experiment with concentrations of 1.17 to 80 p.p.m. of T N T in 1% sewage in a mineralized dilution water (1). The B.O.D. data indicate that all concentrations of T N T down to 1.17 p.p.m. had a decided retarding effect on the observed B.O.D. throughout the &day observation period. The mean percentage of the normal B.O.D. that can be expected with short incubation periods (up to 6 days) in the presence of T N T has been calculated from the data. I n dilutions having oxygen depletions up to about 4 p.p.m., 1 to 2 p.p.m. of T N T reduce the B.O.D. values 15 to 30% below normal. As the T N T concentration increases, a smaller percentage of the normal B.O.D. can be expected. With 80 p.p.m. of TNT, only 44% of the normal B.O.D. was obtained. Although some fluctuations in T N T concentration are shown during the incubation period, 60 to 90% of the initial concentration remained in these samples after 25 days. These data suggest that T N T is not attacked biochemically to any appreciable extent, regardless of the initial concentration. Because of the great importance of the B.O.D. reaction in natural purification in streams, the above experiment was also carried out on colored TNT. The oxygen depletions obtained throughout the incubation period in this experiment decrcased as
~~
OF LIGHT,TEMPERATURE, AND CARBONATE CONCENTRATION ON COLORED T N T FORMATION TABLE 11. EFFECT
SamDle .4
B C D E F
c H
I
J
K
L
11
Observation Period, Days 37 37 37 32 32 32 32 31 31 29 29 26 27 27
N~ carTemp. of Sample, C. bonate First RemainAdded, 2-31/1 der of Entire P.P.M. hours period period 20 None Roomb .... None Rooma 100 Roomb .. 300 Room6 300 Roomb 1000 Roomb 1000
.. .. ..
300 300 300 300 5000 1000 2000
.. .. .. ....
50 80
..
80
80 N 0 E X dilution factor (for samgle as b Varied from about 15" to 26 C.
Equivalent extinction^
T N T Concn., P.P.M. Final Ori ins1 Colored UncolTotal uncJored T N T ored T N T in a-TNT complex a-TNT soh. ~
during for obserLight first entire vation Condition 3 hr. period period 126 0.10 0.15 0.15 Dark 192 9.0 9.0 0.10 Bun 13.6 13.6 1.32 192 Room 20.2 20.2 126 5.05 Room 21.6 21.6 126 5.45 Sun 21.8 126 27.5 9.25 Room 21.4 126 26.0 Sun 10.75 126 17.7 Dark 17.7 2.80 10-12 19.2 126 19.2 4.70 Dark 37 20.8 20.8 126 9.1 Room R&mb 23.4 23.4 126 24.0 Room Roomb 20.0 126 20.0 17.4 Room .... R;O'drh 126 33.5 25.0 33.5 Room Roomb 31.0 26.0 126 31 . O Room Roomb result of treatment described and without sulfite-hydroxide treatment).
....
.... .... ....
0.5 4.3 95.5 80.8 86.0 88.0 80.2 72.9 73.7
78.9
88.5 77.5 95.7 97.5
125.5 147.0 61.0 24.8 18.9 4.6 10.0 50.1 17.8 16.8 18.1 8.5 11.6 11.6
126 151.3 156.5 105.6 104.9 92.6 90.2 123.0 91 5 95.7 106.6 86.0 107.6 109.1
Original T N T Accounted for, % 100
78.4 81.1 83.8 83 3 73.5 71.6 97.6 72.8. 75.9 84.6 68.2 85.1 86.6
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1945 TABLE 111. .
CHANGE IN DILUTB TNT SOLUTIONS UNDER VARIOVS CONDITIONS
PROQRE~SIVE
,
of Initial T N T (42.6 P.P.M.) Remaining As Alpha-TNT Room Sunlight 300 1000 5000 300 1000 100 100 100 100 100 93.2 76.3 31 .O 52.8 71.4 35.0 9.6 9.9 8.0 33.8 53.0 18.3 8.2 7.0 6.6 16.0 20.4 41.1 4.9 7.5 30.8 10.1 6.1 4.0 6.8 21.1 5.4 3.8 4.7 6.3 12.4 5.4 5.6 4.9 6.3 7.0
As Colored TNT Room Sunlight 3000 1000" 5000" 300 lo00 0 0 0 0 0 6.1 25.6 67.6 4411 8.4 ;5 61.3 77.9 20.4 62.1 65.0 33.8 70.7 70.0 67.6 74.4 62.2 56:6 50:7 62.7 70:4 50:s 56:6 4i:4 60.1 63.6 50.9 66.6 50.0 66.0 58.7 52.1 48.8 47.4 66.0 58.7 50.7
Time.of Reactron Initial 4 hr. 1 day 3 days 4 days 5 days 7 days 14 days 26 days 36 days
939
+
Colored Alpha Room Sunlight 1000 5000 300 1000 100 100 100 .loo 101.9 100 ... 96.2 87.6 96.9 94.0 89.0 78.2 86.8 72.8 90.4 68.8 74.6
.
...
..
...
...
... ... ...
300 100 99.3 91.8 91.5
...
...
...
... ...
...
91.5 93.4 81.2 78.4 73.0
...
77.9 70.4 65.0 65.0
64.4 54.9 56.8 55.6
65: 7 61.9 55.2
... ...
54.5 53.8 53.1
Sodium carbonate concentration, in p.p.m.
0
OXYGENDEPLETIONS AND (UNCOMBINED) CY-TNT CONCBNTRATIONS IN A SEWAGE DILUTION AFTER VARIOUS TABLE IV. BIOCHEMICAL PERIODS OF INCUBATION
'IPNT+ 80 P.P.M.
Days Incubated
ftott~. 1 2 3 4 6 10 25 Mean"
b
+ 35 P.P.M.
+
4- 22.0 P.P.M. TNT
D , 1% Sewa
E, 1% Sewa e 10.9 P.P.M. %NT % of o/ of % of o/ of % of 7 of n%& oxy en normal TX~T oxy en normal T%T o x y en normal T%T Oxy en d?p?e- T N T oxy en re; d & - TNT ow en re: d& T N T oxy en red&TNT oxy en re; tton, concn., de$* maintion, concn., d e $ - maintion, conon., de& maintion, concn., de& mainp.p.m. p.p.m. tion tng p.p.m. p.p.m. tion ing p.p.rp. p.p.m. tion ing p.p.m. p.p.m. tion mg 55.0 83.6 1.12 0.81 47.9 88.0 0.93 18.8 87.5 8.5 66.3 78.0 0 0 70 53.8 94.2 9.6 58.0 08.1 1.38 57.1 85.1 1.28 21.2 1.36 91.2 51.7 1.23 78 1.64 19.7 62.2 87.6 1.87 9.2 59.6 84.4 1.66 52.5 95.3 97.7 42.3 1.33 78.2 47.8 96.3 1.78 21.8 51.3 96.9 2.18 10.4 62.8 95.4 1.66 42.3 102.2 1.47 81.8 2.12 21.2 55.4 94.2 59.5 84.6 9.4 65.5 86.2 2.51 2.28 88.7 41 .O 1.57 71 19.8 90.6 88.1 9.6 .. 94.1 .. 88.1 76.8 18.9 .. 87.4 .. 9.1 84.1 .. .. 91.6 83.5 73.3 44.3 53.0 53.5 62.4 #NT
Tx~G
Oxy en de.p?etion, p.p.m. 1.69 2.38 3.14 3.49 3.83
.. ..
... ...
1% Sewage T N T based on E observation, p.p.m. 1 0.228 f 0.205 :3 0.274 4 0.183 6 0,217 10 0.k25 25 Mean" 0
C, 1% Sewa e
E , 1% Sewa e
A , 1% Sewage
F, 1% Sews e 1.04 1.59 2.14 2.60 2.77
+
3.5 P.P.M. ~ N T 48.6 1.70 61.5 55.7 1.95 66.8 58.9 2.06 68.2 72.9 2.55 74.9 68.9 2.41 72.3 2.82 80.6 2.59 74.0 68.7
....
.. ..
....
..
..
..
+
G', 1% Sewa b 1.8 P.P.M. %NT 1.16 1.01 68.6 86.1 0.91 64.3 50.6 1.53 2.28 1.08 72.6 60.0 1.54 76.9 85.6 2.67 1.13 74.2 62.8 2.84 1.16 64.4 1.11 61.7 71.3
.. ..
.. ..
H,1% Sewage 1.51 2.03 2.74 2.76 3.48
....
+
1.17 P.P.M. TNT 0.537 89.3 45.9 0.694 85.3 50.8 0.685 87.3 58.5 0.742 79.5 63.4 0.615 86.2 52.6 Oj96 59.5
....
..
85.5
First 6 days. Insufficient sample for the determination.
OXYGEN DEPLETIONS AND TNT CONCENTRATIONS (COLORED AND UNCOMBINED) IN TABLE V. BIOCHEMICAL AFTER VARIOUS PERIODB OF INCURATION
+
Days Incubated at 200 c . Initial" lnitialb 3 5 7
10
25
E , 1% Sewa e 60.6 P.P.M. %NT
a 6
TNT
D , 1% Sewa e
+ 15.2 P.P.M.
%NT
E , 1%
SEWAGE DILUTION
+
Sewa%NT e 7.56 P.P.M.
Oxygen p.p.m.
..
o:is
0.40 0.43 1.70 1.98
Colored Alpha 45.5 15.1 51.5 4.6 43.0 8.7 43.8 8.7
..,
43.0
...
11.0
Total 60.6 56.1 51.7 52.5
54:O
F,1% Sewa e + 3.78 P.P.M. %NT Initial. Initialb 3 5 7 10 25
C,1% Sewaae 4- 30.4 P.P.M.
A
..
i:i4 1.55 1.55 1.97 1.32
2.84 3.08 2.79 2.60
0.16 0.65
3.78 3.68 2.86 3.30
2.59
0.62
3:21
...
0.94 0.60
...
p.p.m. Colored 22.8 22 6 O:SS 21.0 0.84 22.6 1.05 1.86 23.0 2.52
..
...
Alpha 7.6 5.7 6.3 7.2
Total 30.4 28.3 27.3 29.8
5:5
2815
4- 1.89 P.P.M. %NT 1.89 1.42 0.47 2.47 2.18 0.29 1.45 0.00 1.45 1.56 0.25 1.81
0. 1% Sewa e
.. 1143 1.78 2.27 2.32
..
i:is
~:37
i:85
p.p.m.
....
1147 1.14 1.99 2.28
Colored 11.4 11.6 11.2 11.4
10:s
H,1% Sewa e
.. 2101 2.38 2.41 2.85 5.40
Alpha 3.8 1.9 1.8 3.4
Total 15.2 13.5 13.0 14.8
2:9
1319
+
0.95 P.P.M. %NT 0.71 0.24 0.95 0.93 0 15 1.08 0.98 o 00 0.98 1.00 0 14 1.14
0 : o:ii ~
i:27
p.p.m.
..
1108 1.50 1.45 1.83 2.20
T N T Concn., P.P.M. colored Alpha Total 5.68 1.88 7.56 5.80 0.89 6.69 5.40 0.63 6.03 5.60 1.45 7.05
5:75
1:is
7:23
A , 1% Sewage
... ...
2.00 2.53 2.79 3.15 >8.21
Calculated on basis of mixture prepared. Observed on basia of analytical procedure described.
the concentration of TNT was increased. The percentages of normal oxygen depletion for sewage obtained in the presence of colored TNT were calculated from these data and are shown in Table V. The mean percentages of normal depletions for the 3-, 5-, and 7-day periods were calculated and are also shown in Table V. Themmean values may be considered as representing the expected biochemical oxidation performance during the
period of carbonaceous oxidation. Comparison of these mean percentages with similar values from Table IV for CY-TNT indicate that colored TNT is equally as inhibitive of normal biochemical oxidation as the uncolored alpha form. On the basis of these data it must be concluded that rates of natural biochemical purification of organic matter in streams are reduced in the presence of TNT. The retardation to be expected will increase
rNDUSTRIAL AND ENGINEERING CHEMISTRY
910
Vol. 37, No. 10
of T N T per unit of suspended matter was much higher than in the other samples. Although 21 p.p.m. were removed in the first 24 hours, later removal was very slow and did not reach completion in 31 days. Odor tests on these samples from time to time also indicated that the reduction of the sulfur compounds in the various samples was delayed for longer periods in t h e s m ples containing the higher quantities of TNT. In fact, sample D had practically no odor for the first 15 days, but at the end of 36 days i t had a foul odor that was different from that obtained in normal sludge digestion. After 36 days the pH values of all samples were determined; the solids were then separated from the liquor by centrifuging, and the moisture, volatile matter, and ash contents of the solids were determined: XEisture Volatile Ash, %
Sb&,
TIME IN HOURS
Figure 2. Effect of Temperature on Carbonate TNT Color Development in a Solution Containing 126 P.P.M. of TNT
OF a-TNT TABLE VI. RECORD Initial suspended solids, p.p.m. Initial TNT,.p.p.rn. T N T remaining after: 4 hr. 1 day 2 days 3 days 7 days 31 days
E (Control) 200
0 0.58" 0.73" 0.55a 0.66a 0.71" 1.40"
IN
SEWAGESUPERNATANT
A
B
C
182 9.75
161 21.4
134 35.8
100 53.7
8.1 0.8 0.55 0.16 0.05 0.46
21.4 2.40 1.70 0.58 0.43 1.20
35.5 4.65 3.40 2.22 1.92 0.27
52.0 31.0 21.0 17.6 10.1 4.0
%
Color after sulfite-hydroxide treatment, in terms of T N T deducted from readings on all other samples to obtain the net T N T values shown.
with increasing concentrations of TNT, regardless of the form in which i t is present. Roughly 0.6 to 0.8 p.p.m. may be considered the critical concentration below which no substantial retarding action is expected to occur on natural purification. Data on colored T N T remaining through the first 10-day period (Table V) indicate that no reduction of colored T N T can be expected during the natural biochemical purification process. While there was a slight reduction in a-TNT (Table IV), particularly in the lower concentrations, there was no parallel reduction in the colored form. It must be concluded, therefore, that both alpha and colored T N T not only interfere with and reduce the rates of natural purification in streams, but are not attacked biologically and remain for long periods, even in low concentrations. REMOVAL OF TNT IN SEWAGE
PRIMARY TREATMENT FOR a-TNT. An early experiment showed that the suspended organic matter in sewage removed T N T from solution. To study this phenomenon, increasing quantities of a T N T solution were added to domestic sewage, and the progress of anaerobic digestion was followed. The record of original T N T present and the quantity remaining in the supernatant of these sewage samples for a 31-day period is presented in Table VI. These data show that almost no T N T was removed from solution during the first 4 hours of contact with sewage, but by the end of 24 hours the largest portion of T N T was removed from solution in samples A , B, and C. I n sample D the dose
A
B
c
D
7.47 96.0 75.5 24.5
7.05 95.9 81.9 18.1
7.05 97.5 68.6 31.4
7.37 96.3 84.7 15.8
These data indicate that digestion time is increased with T N T concentration. Apparently, little T N T is needed to slow down the digestion. Consequently, although sewage seems to lend itself well to the removal of T N T from solution, difficulties would be encountered later in the digestion of the sludge. PRIMARY T~EATMENT FOR COLORED TNT. Tests were made with colored T N T solution in domestic sewage similar to those described for a-TNT. Increasing quantities of the colored solution containing a total of 133.7 p.p.m. (103.4 p.p.m. colored and 30.3 p.p.m. alpha) T N T were added to portions of raw domestic sewage, and the following data were obtained: A Conirol
D
a
E 7.27 95.1 61.2 38.8
Initial pH of mixt. Initial concn. of SUBpended solids, p Initial 5-day B.iflif;t: p.p.m. Initial T N T (total), p.p.m. T N T remaining after: 24 hours. p.p.m. 5 days, p.p.m. 24 hours, % 5 days, %
7.2
B 8.05
C
D
E
8.35
8.58
8.89
104
95
83
70
62
324
294
260
217
162
0
10.2
26.8
44.9
66.9
0
7.7 4.7 75.5 46.1
18.9 19.6 70.5 73.1
28.8 33.8 64.1 75.3
49.1 41.3 73.4 61.7
...0 ...
These data indicate poor Temoval of colored T N T with the domestic sewage solids, and are in contrast to the effectiveness of such treatment for removal of the alpha compound. ACTIVATED SLUDGETREATMENT. Experiments on the treatc ment of sewage containing T N T with activated sludge were made in the laboratory in bottles. When 30 to 40 p.p.m. of T N T in sewage was fed to activated sludge, a reduction in the rate of sewage purification was obtained. Biological observations indicated such a large reduction in the nonzoogloeal microflora and -fauna as a result of T N T that a complete breakdown in the performance of the sludge would be expected from biological observations only. The chemical data showed that the removal of T N T was very slow, that operation of a plant on a normal aeration cycle of 4 to 6 hours would result in a poorly clarified effluent,
TABLE VII. COMPARISON OF RESULTSOF FEEDING COLORED AND a-TNT WITH SEWAGE TO ACTIVATED SLUDGE
+
Sewa e =-T%T
Mean sludge suspended solids, p.p.m. 4210 Mean B.O.D. of sewage feed, p.p.m. 365 Mean B.O.D. of 24-hr. effluent, p.p.m. 20 57.9' Mean % reduction of B.O.D.after aeration for 4.5 hours 86.6 24 hours 94.4 38.0 Mean T N T fed, p.p.m. 0.72 Mean T N T in 24-hr. effluent, p.p.m. Mean % reduction in T N T in 24-hr. aeration 98.0 Effect on bioloeical counts Over 90% reduction Effect on settling qualities of sludge None I
0
Immediately after mixing.
+
Sewa e Colore3 TNT 2599 248 10.5 48. tP 84.1 91.2 36.7 15.5 5.9
N o notiaeable e5ect None
October, 1945
INDUSTRIAL AND ENGINEERING CHEMISTRY
and that aeration periods of 24 hours or more would be required for removal of more than 90% of both T N T and sewage B.O.D. T o permit easy comparison of the effects of colored and a-TNT in sewage on the activated sludge proccss, the results of the experiments with both forms are summarized in Table VII. Neither form of T N T had any detectable effect on the settling qualities of the sludge. The colored form had no appreciable effect on biological counts and was only partially removed in the process. I n fact, an average of only 59.5% of colored T N T was removed in a 24-hour aeration period compared to 98% removal of a-TNT. The process is unsatisfactory for colored wastes. a-TNT can be satisfactorily removed but at the risk of breaking down the entire process if overdosed. The aeration time would also have to be increased considerably, which would increase the cost of treatment. Consequently, i t may be concluded that activated sludge treatment would not be successful for treating T N T wastes in either form. PERCOLATION THROUGH SOIL. As soil seepage is used at one plant for disposing of T N T waste, laboratory experiments were performed to determine the effectiveness of this procedure. Data on filtration of the uncolored T N T solution are summarized in Table VI11 and indicate great difference in the performance of the different soils. The poorest removal performance was obtained with the sand which removed only 9.6 mg. or 10.5% of the T N T applied. The clay soils filtered slowly, as would be expected, and although they removed considerably more T N T than sand, they did not approach the performance of black garden top soil (sample 3); 234 mg. of T N T were applied to the latter, and i t removed 148.1 mg. or 59.8%. Even in this w e the percentage removal of T N T had fallen considerably when the experiment was terminated; and the total T N T absorbed represented only 0.10% of the weight of the soil. To determine to what extent T N T could be washed out of the absorbing soil by fresh water, this experiment was carried further on samples 1 and 4. As i t became evident that the absorbing capacity was abopt exhausted, distilled water was passed through the filter in 100-ml. portions. The quantities of T N T recovered in the wash water on these samples follow: Mg. TNT Recovered from
Distd. Water Washes 1st 100 ml. 2nd 100 ml. 3rd 100 ml. 4th 100 ml. Sth 100 ml. 6th 100 ml. 7th 100 ml. 8th 100 ml. 9th 100 ml. 10th 100 ml. 11th 100 mI. Total Total TNT absorbed, mg. % TNT recovered
Mg. of TNT ReooveredSample 4 Sample 1 2.91 6.75 1.32 0.26 0.12 0.06
2.08 1.19 0.91 0.59
... ... ...
0.34 0.29 0.20
8.61
8.94
... ... ...
9.60 88.7
t
c
941
40
0, 0 a
s s
I-
30
d c
0
8 20
a0
IO
1.0 2.0 Time in Hours
3.0
Figure 3. Effect of Sunlight on Carbonate TNT Color Development in a Solution Containing 126 P.P.M. of TNT
with the black garden soil, which absorbed about 0.14% of its weight of T N T in removing 70.6% of @e T N T from 2200 ml. of solution. Comparison between the percentage removals of a-TNT in Table VI11 and colored T N T in Table IX indfcates that all soils tested were more effective in removing the colored form. Experiments on the removal of colored T N T from the sand filter with distilled water gave variable results. I n three experiments with 500 to 1400 ml. of wash water, from 18 to 65% of absorbed T N T was washed out of the sand. These results suggest that it is more difficult to remove colored T N T from soil after absorption than the uncolored cu-TNT.
0.17 0.16 0.10
61.4 14.6
TABLE VIII. REMOVAL OF ALPHA (UNCOLORED) TNT SOLUTION BY FILTRATION THROUGH SOIL Soil sample' No.
1
Description pf soil
Thwe data indicate that the T N T is rather easily removed from thesand filter. However, in the case of soil sample 4,eleven washes wererequired to remove 14.6% of the absorbed TNT. An additional experiment showed that i t is much more difficult to wash T N T out of black garden soil (sample 3), once it has been absorbed. The experiment was repeated with similar soil samples and a solution containing most of its T N T in the colored form. The data are summarized in Table IX. The sand filter removed 66.3 mg. of colored and 38.17 mg. of a-TNT in the fourteen 100-ml. portions of solution filtered. As the previous experiment showed thst sand is ineffective for removing a-TNT, it is assumed that most of the 44.87mg. of CY-TNTapplied here was converted to the colored form during passage through the sand because of the bigher alkalinity of the water (300 p.p.m. sodium carbonate). The various soils in these experiments removed about 47-84% of the T N T applied. The highest removals were again obtained
No. of 100-ml. portions of s o h . filtered Total TNT applied, mg. Total TNT removed, mg. Mean $70 TNT removed TNT absorbed, % soil wt. (150 gram)
FilIter sand
2
High-
cla.
SOIT
FROM
3 4 5 Like3 Like4 Black but with but wlth garden some more soil clay clay
10.5
22.9
15 234.0 148.1 69.8
9
37.6
148.2 61.4 45.8
6 85.2 64.4 63.8
0.006
0.025
0.10
0.04
0.035
5 91.5
9.60
9 149.1
ACTIVATED CARBON TREATMENT
REMOVAL OF T N T FROM WATER. Experiments on the treat+ ment of wastes with activated carbon and on filtration through a filter of powdered activated carbon were carried out to determine which procedure would be most effective to remove alpha and colored T N T from waste waters. Using 10 grams of Cliffchar R coarse in such a filter, 100% removal was obtained from a solution containing 130.4 p.p.m. of a-TNT (uncolored) on the first thirteen of the 100-ml. portions filtered. The percentage removal
INDUSTRIAL AND ENGINEERING CHEMISTRY
942
TABLE IX. REMOVAL OF COMBINED (COLORED) Th’T Soil sample No. Description of soil Form of TNT No. of 100-ml. portions of soln. filtered Total T N T applied, mg. Colored T N T as % of total applied Total TNT removed mg. Mean % of TNT reAoved Total TNT applied. mg. Total TNT removed, mg. Mean Yo of total TNT removed T N T sbsorbed. % of soil wt.
1
2
Filter Sand Colored Alpha 14 14 172.8 44.87 79.38 66.3 38:i7 38.4 85.09 217.67 104.47 48.0 0.07
High-Clay Soil Cblored Alpha ir 17 183.5 51.23 78.17 63.3 43164 34.5 84.98 234.73 109.94 48.8 0.07
then slowly fell from 99.3 on the fourteenth portion to 36.7 on the twenty-seventh and continued at this level through the thirtieth portion when the experiment was. terminated. I n this experiment 391.2 mg. of TPTT were put through the filter in 3 liters of solution, and 313.2 mg. or 80% was removed. TGo additional filtration experiments were run with Cliffchar R fine. I n the first, a considerable quantity of the fine activated carbon was washed through the filter into the effluent, and this mechanical difficulty reduced the efficiency. However, 3 liters of solution containing 391.2 mg. of (I-TKT were filtered through, and 374.1 mg. or 95.6% of the T N T was removed. I n the last experiment a larger bed of glass wool was used to retain the fine Cliffchar and the filter rate was reduced slightly. Then 3.5 liters of solution containing 522 mg. of T N T were filtered through, and 482 mg. or 92.6% were removed. On the b&sis of the a-TNT removed in the last experiment, it may be concluded that the fine activated carbon is about forty-eight times more effective in removino; T N T than the best soil sample. Trial experiments on filtration of colored T N T solutions through fine activated carbon filters indicated filter clogging, with such a great reduction in the rate of filtration that the experiments were abandoned. These trials indicated that filtration of the colored solution through carbon would be more difficult and less successful than filtration of e-TNT solutions. POWDERED ACTIVATEDCARBON. The treatment of T N T solution with powdered activated carbon, as in water purification practice, was tried next. Doses of Cliffchar R fine of 0.3,0.6, and 0.9 gram were added to liter portions of T N T solution, and the samples were aerated for one hour. The carbon was then separated by filtration through paper, and the T N T remaining in the filtrate was determined: 121.8 P.P.M. a-TNT Carbc- ’--P.P. T N T removed Mg. 82.4 118.3 120.7 97.6 99.5 Per cent 67.9 Mg./g. carbon 274.6 197.8 134.1
115.4 P.P.M. Colored TNT
46.1 40.0
153.8
55.4 48.0 92.3
56.1 48.7 62.6
These results indicate that treatment with powdered activated carbon is definitely more effective than filtration through carbon. They show further that it is more difficult to treat colored than a-TNT by either method. The same dose of carbon removes only about half as much of the colored form as the alpha form. Mechanical stirring and bubble aeration were found equally effective in removing a-TNT with activated carbon. With vigorous mixing of the carbon in the solution, 5-minute contact is sufficient t o remove 98% of a-TNT from ordinary waste solutions with an adequate carbon dose. With slow stirring or mixing, 15 to 30 minutes of contact may be required. When the carbon dose is insufficient, periods of mixing and contact up to 2 hours did not increase the percentage removal significantly over that accomplished in 15 minutes. Although the doses of carbon required were large (equivalent to about 17-50 grains per gallon of waste), they would be practicable for the volumes of waste at loading plants. About 50,000 gallons of waste per day with the T N T largely in the alpha form
FROM
Vol. 37, No. 10
SOLUTION BY SOILFILTRATION
3 Black Garden Top Soil . Colored Alpha 22 22 232.3 67.76 77.42 148.9 62:95 63.9 94.85 300.05 211.85 70.6 0.14
4 Like 3 but with Some Clay Colored Alpha 18 18 186.3 53.28 77.76 133.1 5i:45 71.5 96.48 239.58 184.55 77.0 0.12
5 Like 4 but with More Clay Colored Alpha 6 6 67.1 17.62 79.20 54.7 16:98 81.5 95.92 84.72 71.68 84.6
..
might be effectively treated (80 to 90% removal of TNT) with 100 to 300 pounds of activated carbon per day. With carbon selling at about $90.00 per ton, the carbon costs of treatment might be estimated to run from $4.50 to $15.00 per day, depending on the kind of carbon used, the effectiveness of the mixing and holding system provided, and the quantity and form of T N T in solution. DISCUSSION
I n deciding on a corrective procedure for pollution problems at a T N T shell-loading plant, an important factor is the quantity of flow, which is normally on the order of 50,000 gallons per day. This flow is relatively minor compared with flows from T N T manufacturing plants. On the other hand, shell- and bombloading plants are frequently located on small streams and may require corrective measures despite the small magnitude of flow involved. The disadvantage brought out by the study of disposal by seepage through soil is that, sooner or later, the ground will become saturated with T N T and lose its capacity for removal. In the case of treatment with activated carbon, a treatment plant may operate indefinitely with satisfactory results and with only a minor problem of disposal of carbon sludge. I n practice, the carbon may easily be mixed with the waste bJ’ a 15-30 minute contact period in a diffused air aeration tank. The carbontreated waste would not have t o be filtered but could be passed through a plain settling tank with a 24-hour detention period, or into settling ponds of still larger capacity. Settling in this manner would remove 97% of the carbon from the waste. The small amount of carbon lost in the waste effluent would not be objectionable, The settled carbon sludge could periodically be removed from the settling tank or pond for disposal on burning grounds. The shell- and bomb-loading plants now in operation are generally temporary and will be abandoned at the termination of the war. Therefore, disposal by seepage through soil offers ~1 simple solution which should be effective for the short time plants are in operation. The practical installation consists of seepage and evaporation ponds of the size necessary to dispose of the wastes at seepage rates experienced in the particular locality. Seepage is supplemented to a varying degree, depending on locality, by evaporation which in some places may approach or wen exceed the disposal by seepage. To prevent a dangerous accumulation of T N T in the bottom of seepage ponds, it is desirable to take successive ponds from service, allow them to dry, and remove’deposited T N T for disposal at burning grounds. Although no opinion is offered as to hazards connected with disposal of T N T wastes, reasonable precautions would involve placing the ponds or treatment plant at remote locations and handling all dry sludges with care commensurate to the nature of the sludge. SUMMARY
The intensity of the color produced in dilute solutions of (IT N T in natural waters is dependent upon the following factors: concentration of TNT, concentration of normal carbonate or alkaline constituents of the water which raise the pH, temperature,
October, 1945
INDUSTRIAL AND ENGINEERING CHEMISTRY
and liqht conditions. The colored complex 'seems more stable than the aTTNT, and it is difficult to reverse the reaction, once the colored complex is formed. All water samples containing colored T N T must be examined for T N T in both forms. CYTNT solutions in t a p waters of low alkalinity or polluted waters will remain uncolored for 100 days and longer in the dark at 20" C. a-TNT solutions in distilled water can be exposed to .sunlii ht for long periods with the formation of only a trace of colored complex and without other decomposition. With relatively pure or polluted surface waters, from 40 to 55% of CY-TNT is converted to the colored form in 80 days a t ordinar tem eratures in intermittent sunlight. The percentage of coLred f " T formed can be increased to 90% or more in one day or less by increasing the alkaline constituents of the water and/or the tern perature The conversion of a-TNT to the colored form is considered the principal reaction during rolonged storage of T N T solutions. During this conversion, Rowever, there is a slow reduction of total T N T which depends to a large extent upon carbonate concentration or pH and light conditions. I n the surface and polluted water samples tested, 65 to 75% of the original T N T remained in one form or the other after 80 days in intermittent wnlight. I n water containing 300 to 1000 p.p.m. of normal carbonate, 53 to 55% of the T N T remained (largely in the colored form) after 36 days in intermittent sunlight. This decomposition reaction is considered too slow for practical applicat,ion. Concentrations of a-TNT above 1.0 p.p.m. have a retarding effect on the biochemical oxidation of sewage. There is little biochemical removal of T N T as the result of biochemical oxidation in dilute sewage. Colored T N T was equally as inhibitive as ~Y-TNTto normal biochemical oxidation of organic matter dunng the carbonaceous stage. The study of colored T N T wastes indicated that no reduction of the color can be expected by natural biochemical purification in streams. Raw domestic sewage at p H values of 7.2 to 7.8 removed concentrations of a-TNT up to about 35 p.p.m. from solution in a 24-hour contact period. The quantity of T N T removed seems
.
943
to depend upon the suspended organic matter in the sewage. The rate of anaerobic digestion of sewage solids is decreased considerably by the TN'I' absorbed. It was more difficult to remove colored T N T from solution during primary treatment of sewage than a-TNT. Even with concentrations of a-TNT as low as 30 p.p.m. in sewage, activated sludge treatment requires aeration periods up to 24 hours for 90% removal of both T N T and B.O.D. Although colored T N T did not inhibit the process as much as alpha, i t was not removed so readily. Filtration experiments indicated that a black garden soil was best for removing TNT. Such soils might be expected to remove a total amount of T N T up to about 0.1% of their weight. Colored T N T is removed more effectively by all soils than a-TNT. Alkalinizing the waste slightly with soda ash to convert the T N T to the colored form is advantageous for soil percolation. As the absorption capacity of the soil becomes exhausted, fresh water removes some of the absorbed TNT. Dosing and mixing activated carbon into the waste were more effective in removing T N T than filtration through carbon. CYT N T was removed from solution more readily than the colored derivative. A satisfactory chemical treatment of T N T wastes from shell-loading plants would involve holding the T N T in the alpha form, followed by treatment with activated carbon to remove i t from solution. Such a procedure is considered practical for the volumes of waste discharged from shell-loading plants. LITERATURE CITED
(1) Ruchhoft, C. C.. Sewage Works J.,13, 669 (1941). (2) Ruchhoft, C. C., and Meckler, W. G., IND.ENQ.CHEM., ANAL. ED.,17, 430 (1946). (3) Schott, Stuart, Ruchhoft, C. C., and Megregian, Stephen, IND. ENQ.CHEW,35, 1122 (1943).
PRESENTED as part of the Symposium on Industrial Wastes before the Division of Water, Sewage, and Sanitation Chemistry at the 108th Meeting of the AMERICAN CHEMICAL SOCIETY in New York, N. Y .
CARBOXYMETHYLCELLULOSE Uses and Applications C . B. HOLLABAUGH, LELAND H. BURT,AND ANNA PETERSON WALSH Hercules Powder Company, Wilmington,Del.
T
HE newest member of the cellulose derivative family to be introduced commercially, carboxymethylcellulose, is finding wide acceptance in industry. It is the reaction product of monochloroacetic acid on alkali cellulose, and is generally supplied to the trade as the sodium salt which is a white, granular, odorless, and tasteless powder. This salt is readily soluble or dispersible in water or alkaline solutions to form highly viscous solutions useful for their thickening, suspending, and stabilizing properties; furthermore, these solutions can be evaporated to form tough films. The sodium salt of carboxymethylcellulose is known in the trade by several different names including cellulose gum, sodium cellulose glycolate, Carboxymethocel, Collocel, and CMC. The first two are used as general trade designations; the last three are trade names 'for specific types sold by individual producers. A reasonably complete summary of published literature (both patents and technical articles) on carboxymethylcellulose and its derivatives is assembled here. No effort has been made to evaluate the literature references, because commercial exploitation of carboxymethylcellulose is so recent and is expanding at such a rate that any critical evaluation could be out of date before publication. Research in this laboratory has been carried out on possible usefub applications of the product. Conclusions not yet published are cited throughout this paper without literature
references; they are for the reader's use in conjunction with his study of the references cited. Since i t was first developed by Jansen (40)in Germany toward the end of World War I, carboxymethylcellulose has been suggested as a substitute for such products as gelatin, glue, gum arabic, agar-agar, carragheen moss, tragacanth, cherry gum, wheat gluten, and locust bean gum (33, 40). The original Jansen process was later improved upon by Chowdhury (6) and Hhppler (33). Carboxymethylcellulose is usually used in the form of its sodium salt (cellulose gum) which, so far, is its most important industrial derivative (3). Low-substituted types, soluble in alkali but not in water (20,60), are known. A highly substituted form (IO), insoluble in alkali or water but soluble in organic solvents, has also been produced. The potassium salt resembles the sodium salt in many of its properties and gives a similar solution in water. The ammonium salt also is water soluble, and is particularly interesting because i t is unstable and loses ammonia on heating to 50-60" C. The chief insoluble salts of carboxymethylcellulose so far investigated are those of lead, silver, mercury, and aluminum, all of which are colorless, the copper and nickel salts which are blue, and the ferric salt which is red. Generally speaking, sodium carboxymethylcellulose is indicated wherever hydrophilic colloids possessing marked suspending.
