Treatment of Fiberboard
pigments as well as paper stock are present in the waste t o be treated. The waste is substantially neutral in reaction. Various methods of filtration were investigated; the data given in the table are representative. They show that the color is mainly due to suspended solids which are largely removed in filtration. The contamination, as measured by the value for oxygen consumed, is also substantially in suspension, being reduced by 75 per cent by filtration. The reduction in solid content by filtration is much less and indicates relatively large amounts of dissolved solids. From a practical standpoint, filtration of this waste proved unsatisfactory. Only 2.2 gallons per square foot per hour were obtained in a 6.75-minute cycle. The rate dropped rapidly and the cake was not suitable for continuous discharge from a vacuum filter. Therefore filter medium would have to be added. That is out of the question from the standpoint of cost. The material settles substantially in 24 hours. The slightly opalescent upper layer contained only 15 p. p. m. of suspended solids. This was 1.25 pounds per 1000 gallons as compared with 1.64 reported for paper mill waste by a somewhat different treatment (4). The sludge, which was relatively small in volume, contained over 2 per cent of solids as compared with 1.3 per cent reported for the paper mill waste (4).
Waste FOSTER DEE SNELL Foster D.Snell, Inc., Brooklyn, N. Y.
Waste from the manufacture of black and red fiberboard from newspaper and rope stock was studied. Filtration was unsatisfactory. The suspended matter amounting to 134 p. p. m. was reduced to 15 p. p. m. by sedimentation for 24 hours. Since the sludge is not offensive in its properties, sedimentation without chemical treatment is recommended.
Total solids Organic solids Inoraanic solids Oxygen consumed Lovibond color of 25.4 mm.
F
IBERBOARD made from newspaper and rope stock is an article of commerce and yields industrial waste requiring treatment. The problem is analogous t o treatment of the white water from the paper mill. I n such plants, save-alls are commonly used. These operate by screening the waste, in which case they are relatively inefficient, or by sedimentation. A combination of the two has been found satisfactory (2, 8). By combined filtration and sedimentation, fiber and slime are separated (1). The process involves large filters with strong suction. Reduction to 1.64 pounds per 1000 gallons by sedimentation, accompanied by mechanical action, has been reported. A patented process (7) recovers fiber by precipitation with zinc hydroxide and subsequently recovers the fiber by dissolving the metal hydroxide. If a closed system (6) is feasible, the problem does not exist. The factors involved have been reviewed (3). I n the operation of the plant under discussion the paper stock is pulped with water. This passes through steps analogous to those of a paper mill and finally is distributed to a felt, The wash water used in this operation carries substantial amounts of fiber and pigment, and goes to a storage tank for use as make-up water. The amount going to this tank is in excess of that which can be used and overflows through suitable conduits. Analyses show that over 80 per cent of the solids are pigment rather than fiber. Dyestuffs and sizing materials are absent. The rate of flow from discharge over a weir was calculated a t 156,000 gallons per day. Two representative samples were accumulated by taking small samples over a period of a day on two different days. The two were so similar that data on only one are reported. As in previous papers of this series ( 5 ) ,data on total solids, loss on ignition, oxygen consumed, and color readings in a 25.4-mm. Lovibond cell were obtained. I n addition suspended solids were obtained by filtration. Since the finished stock is colored red at some times and black at others, suspended
Original P. p . m. 802 164 638
40 5 . 0 red
5 . 0 ellow 5.0 %he
Filtrate P. p . m. 668 94 574 10
0 . i ;‘ellow
...
Upper Layer from 24-Hr. Sedimentation P.p . m. 683 97
586 11
1 . 5 red 1 o ellow 1 oL e
The color of the sedimented liquid is shown in the above table. While not fully satisfactory, it is not seriously colored when compared with many other treated wastes. The total waste contains only 176 pounds of suspended solids of which less than 30 pounds is fiber. Of these, 155 pounds can be removed by 24-hour detention. Therefore provision was made for discharge of the waste to a natural lagoon of an average depth of about 4 feet (having a capacity for slightly over 24-hour detention). It was used for an extended period with only occasional cleaning to remove sludge. Although some slight evidence of putrefaction was observed, the amount was not important, bad odors did not arise, and the dissolved oxygen was not dangerously reduced. The conclusion reached is that for this type of waste the most economical treatment is purely a matter of sedimentation with loss of suspended values. The value of such suspended matter does not warrant more careful treatment.
Literature Cited (1) Cunningham, Noel, Paper Trade J . , 82, 223, 225 (1926); P a p e r M i l l , 49, 110, 112 (1926); P a p e r I n d . , 7, 1993, 1995 (1926). (2) Gilman, E. H., and Milham, E. G., P a p e r I n d . , 8, 461-2 (1926); Paper M i l l , 49, No. 23, 38 (1926) ; P a p e r Trade J., 82, No. 24, 49 (1926). (3) Graef, 0. K., Paper I n d . , 15, 249-53 (1933). (4) Niks, N. J., Ibid., 8, 464, 467 (1926); P a p e r Trade J.,82, No. 24, 50 (1926). (5) Snell, F. D., et ai., Am. D y e s t u f f Reptr., 16, 54 (1927); IND. ENQ. CHEM.,19, 237 (1927), 2 0 , 2 4 0 (1928), 21, 210 (1929), 26, 5801 (1934); 27, 825-27 (1935). (6) Strachan, Jas., World’s Paper Trade REV.,89, 704, 770, 772 (1928) ; Paper-Maker, 75, 339B (1928). (7) Thomsen, A. M., U. S. Patent 1,870,881 (1932). (8) Wents, S. C., P a p e r I n d , , 8 , 460-1 (1926); P a p e r M i l l , 49, No. 24, 36, 38 (1926); P a p e r Trade J . , 82, No. 24, 50 (1926). RECEIVXD Beptember 24, 1936. Presented before the Division of Water, Sewage, and Sanitation Chemistry at the 92nd Meeting of the American Chemical Society, Pittsburgh, Pa., September 7 to 11, 1936.
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