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INDUSTRIAL AND ENGINEERING CHEMISTRY I
825
such as different petroleum fractions from similar crude oils.
Acknowledgments The authors wish to express their appreciation for the assistance given by several students in petroleum engineering a t the University of Oklahoma. William A. Pearce, Curtiss W. Cannon, and Joseph E. Johnson were of great aid in the operation of the tower.
Literature Cited
FIGURE11. PRESSURE DROPACROSS TRAYVS. LIQUID RATEAS A FUNCTION OF LINEAR VELOCITY OF VAPOR Temperature, SOo F.; pressure, 14.3 lb. per sq. in. abs.: kerosene-air system
(1) Ashraf, Cubbage, and Huntington, IKD.ENQ. CHEM.,26, 1068 (1934). (2) Carey, Chemical Engineers’Handbook, p. 1197, /oo 200 SO0 400 500 New York, McGraw-Hill Book Co., 1934. MASS v,%ocrry * / m / m F S (3) Chillas and Weir, IND.EXQ.CHEM.,22, 206 (1930). FIGURE12. ENTRAINMENT vs. (4) Holbrook and Baker, Ibid., 26, 1063 (1934). MASS VELOCITY OF VAPORAS A (5) Kallam, F. L., Petroleum Engr., 5, 33 (Apr., FUNCTION OF TEMPERATURE AND 1934). LIQUID RATE (6) I b i d . , 5, 29 (June, 1934). Pressure, 14.3 lb. peF sq. in. abs.: 20-in. (7) Rhodes, IND.ENQ.CHEM.,27, 272 (1935). tray spacing; water-air system ( 8 ) Rogers and Thiele, Ibid., 26, 524 (1934). (9) Sherwood and Jenny, Ibid., 27, 265 (1935). (10) Souders and Brown, Ibid., 26, 98 (1934). because of the vast
not be comDared with kerosene directly difference and physicafProperties Of the two liquids* A direct comparison between f3everal liquids can be made only if the liquids are of a similar chemical nature,
R ~ ~ E I Maroh ~ E D 12, 1935, The data, of this paper are t o be presented by W. T. Pyott in partial fulfillment of the requirements for the master of science degree in petroleum engineering, University of Oklahoma.
Treatment of Trade Waste with Activated Carbon
FOSTER DEE SNELL Foster D. Snell, hc., Brooklyn, N. Y.
0
F T H E various possible methods of treatment of dye waste, coagulation has received the main consideration. Bleaching and the use of activated carbon have received only passing mention (1). A process of treatment with activated carbon has been carried through the steps of laboratory development. Since, owing to local conditions, this has not been and will not be put into operation in the near future, it seems worth while to publish the preliminary information available because the data indicate the method to be more suitable than coagulation, a t least for this plant. I n comparison with previous papers (1-5) of this series on the chemical treatment of trade waste, it illustrates the variation possible in the waste disposal problems of individual plants of the same general nature. Although the data presented are laboratory data, they were obtained in all cases on waste from the commercial operations. This plant dyes and prints silk and silk-mixed goods. The waste is chiefly from the dye baths, but in addition there is a small volume of very concentrated waste from the printing department at the end of each day. There is a discharge from the boil-off department and both acid and alkaline baths are used, of which the latter is discharged only a t intervals.
The plant under discussion dyes silk and silk-mixed goods. Laboratory data indicate that treatment of the waste, after diversion of printing waste and boil-off, with 6 pounds of activated carbon per 1000 gallons i s more efficient in removal of color than coagulation. Loss on ignition of the solids is not substantially reduced. The material cost is about 2 cents per 1000 gallons. Considering the cost of equipment and operation the cost is probably about half that of coagulation. Sanitary sewage is disposed of separately and does not enter the problem.
Waste Discharged As is often the case with a dye plant, the volume of discharge varies seasonally. The maximum daily consumption of water is estimated at 150,000 gallons, with seasonal reductions to one-third of that amount. This water is largely discharged as a composite of dye and wash baths. Miscellaneous discharges are as follows:
826 Cencd. dye waste dcid waste Boil-off Caustic waste Dilute dye waste
ISDUSTRIAL AND ENGISEERIXG CHEMISTRY 2-8 Ib. daily 10 gal. of 15% acetic acid, 2-4 gal. suifirio acid daily 2000 gallons daily 1000 gallons of 1.5% caustic soda s o h , once every 3 mo. Abous 150,000 gal.
Nature and Disposal of RIiscellaneous T a s t e s This plant is permitted to discharge a limited volume of waste through a local sewer system. In addition to the sanitary waste, therefore, certain of these miscellaneous TTastes should be so treated. The small daily volume of concentrated dye waste should be so treated. The acid waste is discharged continuously viith the dye waste and the amount is not large enough to counterbalance the buffering action of other materials present. Any change in process resulting in an intermittent rather than continuous discharge will necessitate the provision of a larger averaging basin. The cost of treatment of the boil-off liquor would be high, and, since its volume is comparatively small, it should be discharged directly to the sewer system. On acidifying, the boil-off liquor yields one per cent of oil separation and, if it could not be diverted-, this liquor nould have t o be acidtreated and the resulting acid waste blended with the dye waste. The treatment of this type of waste is a well-developed technic. The caustic waste discharged once every 3 months has a color very much like that of the dye waste. It was found that on neutralization it could be treated in the same way as the dye wastes. Such batch neutralization is not expensive when it is considered that sr theoretical quantity of 340 pounds of 66" BB. sulfuric acid would be required only a t %month intervals The waste should not be discharged to the sewer without neutralization, and after neutralization the use of part of the available sewer capacity for that purpose is not necessary.
Treatment of Dye Waste
In this plant, therefore, the problem is practically reduced t o treatment of a substantially neutral solution containing
S'OL. 27, NO. T
dye wastes. Representative samples of such waste were taken on two separate days, each sample being a oomposite of quart samples taken a t hourly intervals throughout the day. The two samples were examined as in previous studies (4) by determination of total solids a t 110" C., oxygen consumed by a modified acid permanganate method, and color readings for a 5Omrn. layer in the Lovibond tintometer. From the total solids, the loss on ignition at a dull red hear was taken and considered to be organic, solids. Table 1 gives the data obtained on the samples for the 2 days. It is evident from these data that vaste A vas little contaminated except as l o color, so that the problem was mainly one of color removal. Waste was dark and opaque. On standing several. days, solid matter began to flocculate and. after standing several days more, it could be filtered to give a liquor practically identical with waste A. Since waste B was more highly contaminated, it was used as the basis for experimental n~orlion methods of treatment, which were ther confirmed on waste A.
Total golid: Organic sohds Inorganic solids Oxygen consumed Color
45.8 22.4 23.4 10.2 9 red a y@!low
127.2 43.2 84.0 17.6 40 red 2 ellon 0
%he
Experimental. Methods of Tseatmeait Experimental coagulations were carried out and lime or srluni and lime. The copperas removed more of the yellow color and the alum more of the red, but the total color removal was practically the same in each case, From experiinental dosages a t various concentrations the conchsion was reached that 2 pounds of copperas and 2 pounds of lime per 1000 gallons of waste gave the best results obtahable by this method. Data on a samde of waste B so treated a r e shown in Table 11. T h e sludge obtained amounted to 5 per cent by volume. The r e s u l t a n t waste was satisfactory for discharge into the near-by river except for color, Ira. this case the color was con sidered to be one of the most, if not the most, important factor, Waste B was treated experimentally with a high grade of deooloriaing carbon. It was found that 6 pounds of the carbon per. 1000 gallons of waste gave the maximum degree of decolorisation. Color removal by this method was muoh better than by the coagulation m e t h o d , Analytical data on the waste treated in this way are also shown in. Table 11, These data show both the color and total solids to b e
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INDUSTRIAL AND ENGINEERING CHEMISTRY
less than after the coagulation treatment. However, the oxygen consumed is not substantially reduced by this treatment. This treatment yields no sludge for removal, and the better color indicates it to be the more effective treatment for this particular problem. As counterbalancing factors, one method of treatment gives only incomplete removal of color, and the other does not remove the oxygen-consuming substances. Under special conditions, as in this case where color is important, the carbon treatment appears to furnish a feasible method of treatment.
821
most suitable. From the drier it is discharged with about 5 per cent moisture content to an electric revivifier such as is used in the sugar industry. The time required for revivification is less than one hour and the current consumed is 370 kw. per ton of carbon.
Cost of Treatment
The price of the grade of activated carbon used is 13 cents a pound. The day-to-day cost for the carbon used consists of the cost of reactivating, Details of Carbon t o g e t h e r w i t h the Treatment value of any carbon lost in the p r o c e s s . B a s e d on t h e exThe amount of carbon p e r i m e n t a1 results, f o u n d desirable for t h e following is an t r e a t m e n t of t h e outline of the method waste is 6 pounds per of application of the 1000 gallons, but the treatment, subject to same carbon is availdetailed check on the able for re-use a numaverage waste over a ber of times. A consubstantial period of s e r v a t i v e figure for time. the number of times The wastes should i t may be re-used is first be collected and three, on which basis well mixed in a small the reactivating procaveraging basin. A ess would be applied detention of 1 to 2 to 2 pounds of carbon hours should be adep e r 1000 gallons of quate, and it is posCARBON REVIVIFYING UNITS IN LARGE-SCALE OPERATION waste. The cost of sible t h a t f u r t h e r reactivation i s e s t i study will permit remated a t $0.005 per pound, giving a cost of 1 cent per 1000 galduction of this estimated time. A longer averaging period lons. The loss on revivification is about 3 per cent. Estimatwould, in general, be essential for a coagulation treatment, ing on that basis, this means the loss of 0.06 pound of carbon but the carbon treatment will permit of greater variation in a t 13 cents a pound, giving an additional cost of 1 cent per the composition of the waste being treated, provided ex1000 gallons. The total cost therefore is estimated as 2 tremes of acidity and alkalinity are absent. cents per 1000 gallons. Costs were also estimated for the materials used in the experimental coagulation treatment, the TABLE11. DATAON TREATED WASTES cost per 1000 gallons being about 3 cents. Dye Waste B It is not the purpose of this paper to discuss equipment Treated by Treated by coagulation adsorption costs in detail but it may be well to outline them. They Parts ver 100,000 comprise an averaging basin of not over 30,000 gallons ca103.2 111.8 Total solids pacity, a treatment basin of 2000 gallons capacity, a filter to 19.2 41.6 Organic solids 61.6 92.6 Inorganic solids handle 20,000 gallons per hour, an electric drier to handle 2.0 16.8 Oxygen consumed 300 pounds of carbon a day and an electric reactivator of the 4 red 2 yellow Color 3 yellow same capacity, together with necessary accessories such as pumps, motors, etc An existing sump is suitable for use as the averaging basin. This contrasts with the necessary From the averaging basin the effluent should be discharged sludge-settling basin and means of sludge disposal necessary t o a small treating basin to receive the carbon treatment. by coagulation. Taking everything into consideration, the This basin need not be large, as the period of treatment need over-all cost of carbon treatment would probably be about be only about 5 minutes. The carbon should be added as a half the cost of coagulation. concentrated aqueous suspension and mixed during passage of the waste through an entering calender with mixing baffles. Acknowledgment From this calender the effluent should be pumped to a filter The results given in this paper were obtained in co6perato remove the carbon and the filtrate discharged directly to tion with Gerald W. Knight, consulting sanitary engineer of the river. The used carbon, until inactive, can be washed Passaic, New Jersey. Beatrice F. Grey assisted in preparing out of the filter by reversing the flow of liquid (using clear the data for publication. water), and such a suspension can be used for further treatment. Literature Cited More carbon is specified than required for complete de(1) Snell, F. D., Am. DyestufReptr., 16, 54 (1927). colorization because experimentally it worked more effecENG.CHEM.,21,210 (1929). (2) Snell, F. D., IND. tively that way, and because, further, it furnished a margin (3) Ibid., 26, 580 (1934). of safety against variation of the composition in a way to reENQ.CHEM.,19, 237 (1927): (4) Snell, F. D., and Bruce, D. S., IND. quire more adsorbing capacity. Am. Duestuff Reptr., 16, 86, 109 (1927). After exhaustion the carbon may be reactivated to very (5) Snell, F. D., and Snell, C. T., IND.ENG.CIIEM.,20, 240 (1928). nearly its original adsorptive capacity. For reactivation RECEIVED February 16, 1935. Presented before the Division of Water, the cake of carbon would be removed from the filter and Sewage, and Sanitation Chemistry at the 89th Meeting of the American dried. For an installation of this size, an electric drier is Chemical Society, New York, N Y . , Agril 22 to 20, 1935. p-
