April 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
and increased the suspended solids content of the effluent. A Cascade aerator was installed t o eliminate the carry-over caused by air entrainment. Temperature fluctuations have an important effect on sedimentation, particularly in the tieatment of white water, because the fibers are light and therefore susceptible to thermal disturbances. Although the average temperature rise that can be tolerated depends to some extent upon the characteristics of the suspended solids, in general an average rise of 3 e F.per hour will not affect the clarity of the effluent if slurry recirculation is used to equalize the temperature before the water reaches the zone when solids separation takes place. With a greater rate of temperature increase, coagulation of white wastes becomes critical, and the installation of an equalization tank should be considered.
619
that is required. I n general, an alum dosage of less than 2.0 pounds per 1000 gallons will be effective for removing the fibers, but more alum will be needed if the waste contains finely divided filler which must also be removed. Sedimentation units are affected by entrained air in the white water, b u t operating difficulties due to entrained air can be avoided by the installation of an air-separation unit. Slurry recirculation eliminates thermal upsets caused by temperature variations of less than 3’ F. per hour. Greater rates of change will increase the suspended solids content of the clarified water. Chemical treatment is particularly applicable to board mills where the recovered fibers can be returned directly t o the process in a concentrated form, as the value of the recovered fibers defrays essentially all operating expenses for the treating plant, LITERATURE CITED
CONCLUSIONS a
White water can be effectively clarified by chemical treatment if effective mixing and slurry recirculation are used; removal of better than 95% suspended solids is obtained by treatment with alum and activated silica. The amount of coagulants needed for effective treatment depends upon the characteristics of the white water and on the degree of clarification and B.O.D. reduction
(1) Knack, M. F., “River Raisin Paper Company’s Approach to
Treatment of Board Mill Wastes,” Fourth Industrial Waste Conference, Purdue University, Sept. 22, 1948. (2) Rudolfs, W., and Axe, E. J., Wuter and Sewage Works, 95,No.6, 21’9 (1948).
(3) Warrick, L. F.,IND. ENG.CHEM.,39,673 (1947). RECEIVED October 8. 1949
TREATMENT OF COTTONFINISHING WASTE LIQUORS GEORGE G. BOGREN Weston & Sampson, Consulting Engineers, Boston, Mass.
2. TRICKLING FILTER. T h e pilot plant expeniments described were conducted This unit is 0.25 acre in area as a step in a program to abate the pollution of a small thesc experiments had and consists of a IO-foot stream receiving the wastes from a large cotton finishing their origin in caustic depth of coarse crushed and peroxide kiers, bleachplant. The finishing plant has a dual sewerage systemstone within a n earth embankment. Wastes are aplight wastes are discharged to the stream without treating, dyeing, mercerizing, plied intermittently by a ment, and the heavier wastes are pumped to a treatment and sundry special finishing dosing siphon through a grid plant. Wastes are now receiving primary and partial processes, together with the of fixed nozzles. The aversecondary treatment. Complete secondary treatment is ~ a 5 hwaters which form age daily rate of dosage is necessary in the planned stream pollution abatement 1,100,000 gallons per acre the bulk of the wasteliquors, per day, and the rate durprogram. The wastes vary widely in alkalinity from hour and a small amount of ing the period 7:OO A x . t o to hour. For this reason, and for economic reasons. highdomestic sewage. 5:OO P.M. is 1,600,000galrate trickling filters seemed the most promising method of Table I shows the comlons per acre per day. The average B.O.D. loading is position of the waste liquors treatment. Pilot plant experiments showed that B.O.D. 0.15 pound per cubic yard removal of at least 60% was possible at a rate of filtration duiing the period of these of filter media. of 10,000,000 gallons per acre per day. experiments. 3. INTERMITTENT FINE The volume of wastes CINDERFILTER.This unit amoun’ s to about 2,000,000 is 1acre in area and consists of a depth of 4 feet of screened cinders varying from 2 inches at gallons per 24 hours, and 60 to 90% of this flow is discharged the bottom t o about 0.3 mm. at the top, underdrained. Trickling between the hours of 7:00 A.M. and 5:00 P.M. Normally the finishfilter effluent is applied intermittently by a pump, through ing plant is in operation 5.5days weekly. wooden distributing troughs. The average rate of dosage is 285,000 gallons per acre per 24 hours.
HE wastes treated in
T
PRESENT T R E A T M E N T M E T H O D S
All the wastes are treated by subsidence, and about 15% by
subsequent trickling filtration through crushed stone and intermittent filtration through a fine cinder filter, which may be described briefly as follows: 1. SUBSIDING BASINS. There are three rectangular horizontal-flow basins, each 32 X 64 feet in area, with an average depth of 17 feet. The period of detention a t average flow is 9.5 hours and during the period 7:OO A.M. to 5:OO P.M., 4.3 hours. The overflow rate at average daily flow is 325 gallons per square foot per 24 hours, and during the period of maximum flow 700 gallons per square foot per 24 hours.
EFFICIENCY O F PRESENT T R E A T M E N T P L A N T
Table I1 shows the average chemical composition of the wastes a t various stages of treatment during the period of operation of the pilot plant. The percentage removal of the significant constituents by various units of the treatment plant during the period of these experiments is shown in Table 111. P I L O T P L A N T STUDIES
Abatement of stream pollution requires that more complete treatment of the entire volume of wastes be undertaken. En-
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
620
largenicnt of the trickling filter and interrnittcnt sand or fine cinder filter was not considered fcasible for the cotton-finishing plant because of the great construction and operation cost of the latter type of filter. Chemical coagulation and clarification methods were likewise not consideied because of the cost of operation and the high degree of supervision required for such processes. The activated sludge process is ill-suited to the wide variations in character and the prcsencac of toxic substances in
Table 1.
Turbidity Color
Parts per Million hrinimum RIarriGilni 160 220 .
.
...
I
f l "v e_e" _
Oxygen consiiined Free aniinonia Total albuminoid ammonia
340 2 1 5.3
310 0.4 4.5
385 3 2 6 0
Alkalinity, total Hydroxide Carbonate Bicarbonate
486 60 423 0
290 0 180 0
740 500 420 100
1565 200 1365
1295 145 1150
1500
Mineral residue on evaporation Total Suspended Dissolved
985 50 935
880 30 810
1160 70 1115
B.O.D. DH Settleable solids,
280 10.6 0.5
240 9.5 0.48
Residue on evaporation Total Suspended Dissolved
Table
II.
'Z
1700 260
355 11.5 0.53
Average Composition of Wastes during Operation of Pilot Plant Parts per RIillion Subsiding Trickling basins filter effluent effluent
Ram wastes Turbidity Color Oxygen consumed Free ammonia Total albuminoid ammonia Alkalinity Total Hydroxide Carbonate Bicarbonate Residue on evaporation Total Suspended Dissolved Mineral residue on evaporation Total Suspended Dissolved B.O.D. !%hble
ihesc wastes. For the foregoing rciiboris, it was decided t1i:it high-rate trickling filters would brat answer the demands and that the expected performance of surh filters could be prcdicf ccl only after pilot plant experiments. DESCRIPTION OF PLANT.Thc plant consisted of a rectangulxr trickling filter to which efflucnt from the existing subsiding basin.. was pumped, an aerating spr:Lv and distributing pan abovc the filter surface, a secondan, subsiding lmsin, and a feed control tank From nhich the pump dischargctl tlir wastes to the filter. Piping, valvci, and float valves permittcd rrcirculation of the filler or srcwndair sulisiding basin cfflurnt . Tlic trirliling filter wa> 3 3 f r e t y u a r p , having an are:] 01 12 q u a i c feet. It was filled t o a depth of 3 5 feet with 1- to 2-inch caruslied stone underlaid bv 12 inrlwq ol 2- to 3-inch stone A v i ics of 1-inch holes w x c b o t r d in Ihc r\ alls of the filter 6 iiirhc3i :~bovcthe bottom, for vcnti1:ttion. Applied wastes nerc (11st ributed from a singlc show 01 sprnv hcad, discharging up\\ artl, ihrough a pan of the same s i x i i i i h r filler surface with '1 -iwh holes 7.5 inc1ic.s on centera The feed pump was a pos~tivctliiplaccment rotary pump IN\ing a m,z\irnum capacity of G giillons per minute. Flow of wastes waq controlled bv varying-head orifices in ronqtant-level tanks. The secondary subsiding babiii 71 ~ L 2.5 F X 10 feet in area, 111 j, nican depth of 28 inches. It was mnuually cleaned of sludges only occasionally. The pilot plant was located in n building, with uindows opcw on all sides for ventilation, except in firezing weather. OPERATYON OF P L I N T . T h e piloi filter was placed in opera tion i n October 1946, after the filter mcdia were seeded with a suspcusion of the biological grotlth o t i the media of the main triclding filter. After 3 months' opciatiori with no appreciable bio1ogic:d action, the pilot plant was shut doon in January. Operation \viis resumed on llpril21, 1947, and coniinucd until mid-Octobcr 1047. During this period, vaijiiig rnl(8s of tloeagc of influent arid wilying rates of recirculation M ( ' I C ) trird. S,imples were collectcd a t intervals ranging from 1 to 3 n c r l \ b :ifter a change in the rafe of feed or recirculation. Thcl p h i i t opciatcd 24 hour? daily 5 l o 5.5 days per week.
Composition of Waste Liquors Sverage 200 Various
solids, %
170
200 Various dyes 340 2.05
dycs 320 1.65
130 Light brown 225 0.70
4.75
4.05
s'arious
5.30
.
Fine cinder filter 2 Pale straw 35 0.!6
0.95
485 60 425 0
460 35 425 0
430 0 175 255
390 0 0 300
1565 200 1365
1445 173 1270
1255 lo0 1108
810 0 810
985 50 935
920 35 885
910 40 870
710 0
280 10.5 0.5
250 10.5 0.03
159 8.5 0.07
Table IV.
Table 111.
a
b c
Influent FloTv'? Wastes Gal./ R1.G. Temp min. A.D.b (2.'' 1.3 6.65 26 1.3 6.63 .. 1.3 6.65 29 1.4 7.15 23.8 1.1 7.15 ,. 1.6 7.65 22 1.7 8.7 9.0 1.9 9.7 22 1.9 9.7 27 2.0 10.2 28 2.0 10.2
..
Removal of Significant Constituents of Wastes during Operation of Pilot Plant __ ______-Prr Cent Removala by Subsiding baiins
Turbidity Oxygen consumed Suspended solids B.O.D. Settleable solids
710
in 6 ,7 0.0
a ?J
TricLling filter 23 80
15
6 13 11 94
14
40 h - 133
Fine cinder filter 99 85 100 93 100
Entii i plant
ne
90 100 96
100
Based on analysis of influent and cfliiicnt. of indicated unit Generally between 50 and 60 01 or l ~ ~ i pcriod i g ~ of t,ime.
Results of Operation of Pilot High-Rate Trickling Filter for Finishing-Plant Wastes ]>arts
7
Date of Sample 1947 7/17 7/22 9/11 6/6 9/30 10/16 1/10 9/25 8/22 8/14 4/22
Vol. 42, No. 4
~
Reciiculation Ratio 1:1 2:l 2:l 0.5:1
1.1:l 1.7:1 0.5:l l.6:l 2:l 2:l 0.8:1
See. Subsidiary Period, Hours 4.3 4.3 1.3C
4.0
1.DC 1.4c 3.3 1.1" 1.OC 0.90 2.8
Influent 205. 211. 252. 80. 303. 325. 143. 246. 308. 233. 228.
B.O.D. Seo. basin effluent 123. 118. 143. 40.7 125. 143. 112. 86.8 130. 171. 211.
hfi!Ii",) .~ I I?-ilrou Sec. Filter basin I~iltcr basin cfflu- efflu- Influ- cfflu- efflu- Influent ent ent ent cnt ent 0.8 . .. ., 180 0 0 is0 0 0 0 0 ,. 240 1.0 .. 500 0 0 240 .. 0 0 ,, 180 !'.'3 0 90 0 .. 380 a.2 ., .. .. 0.5 0 n ., 180 0.9 0 0 C i .. 280 0.2 0 .. . . . . .. 0 O .. ~
~~
_ _ _ _ ~. ..
OxyFen ~- I>i-solved ____ ___
%
Reduction 40.0 44.0 43.3 49.1 58.8 86.0 21.7 64.7 57.8 21.9
Not including recirculated wastes. h1.G.A.D. = million gallons per acre p q r 21 Iiours. Recirculating secondary subsidiary basin effluent: otherwise, filter effluent.
. .>
Influcnt 1.4
...
1.3
...
...
0.7 4.9
:'race 0 ..
..
I
I
.
..
I
.
effluent
..0
effluent
..
0
0 360 0 320
2'8'0 0 0
0 36
0 0
..
.. ..
..
3ih
~
April 1950
. 4
I
INDUSTRIAL AND ENGINEERING CHEMISTRY
RESULTOF OPERATION. Table Iv summarizes the operation and analytical data for the pilot plant. The January 10 sample was collected at the end of the initial 3 months’ operating period, when biological growths failed to establish themselves at the low temperatures. The dissolved oxygen content of the influent was the highest observed during the experiments, because of the inhibiting of aerobic decomposition in the subsiding basins by the low temperature. The April 22 sample was collected the day after the pilot plant was placed in operation after a 3 month’s shutdown. As would be expected, the B.O.D. reduetion was slight. During the remainder of the experiments, the removal of B.O.D. showed a general increase, reaching a maximum of approximately 60% a t a rate of nearly 10,000,000gallons per acre per day. During the same period, the low-rate trickling filter of the main treatment plant was showing an average B.O.D. removal of 40% at an average rate of 1,100,000 gallons per acre per’day. The pilot plant filter carried B.O.D. loads as high as 3.0 pounds per cubic foot, whereas the main filter loading averaged 5% of this amount. The August 14 sample was an exception to the general increase in B.O.D. removal, showing a B.O.D. reduction of only 27.0%. This may have been due to partial clogging of the filter surface with a slimy biological growth, later removed, or to some unre-
621
corded mechanical aberration prior to the time of inspection and sampling. All caustic alkalinity was converted to carbonate or bicarbonate in its passage through the pilot filter. In the design of a wastes treatment plant on the basis of these pilot plant studies, there will be two possibilities of bettering the performance of the pilot plant. First, the dissolved oxygen supply to the influent wastes will be increased to leave a higher residual in the filter effluent. Available head room prevented more desirable aeration of the influent to the pilot filter. Secondly, alterations in the finishing plant sewerage system will permit the diversion to the wastes treatment plant of highly acid wastes now discharged to the river without treatment, thus reducing the excessively high alkalinity of the wastes to be treated. These experiments were not conducted a s a research problem, but rather to obtain a n empirical answer to the question whether these wastes, varying widely in alkalinity, could be treated successfully on shallow high-rate trickling filters. The experiments answer the question in the affirmative and conclude that conservative B.O.D. reductions between 60 and 70% will be possible in a properly designed plant. RECEIVED December 12,1949.
TREATMENT OF COTTON PRINTING AND FINISHING WASTES STUART E. COBURN Metcalf 8t Eddy, Boston, Mass.
T
H I S paper deals with the results of pilot plant tests on treatment of industrial wastes discharged from printing and finishing of cotton and rayon textiles. These tests were made jointly b y Albright & Friel and Metcalf 8z Eddy for the Eddystone plant Of the Jos*
A
pilot plant was operated during 1948 to find the most feasible method of treating cotton printing and finishing wastes before discharge into the Delaware River. It was found that construction costs of a high-rate trickling filter plant would be approximately $45,000 more than a chemical treatment plant, but the net annual charges would be about $25,000 less; the difference in charges was due largely to costs of labor and chemicals. High-rate trickling filters present fewer complications in operation and a less serious sludge-disposal problem. Results are given of analyses of wastes and treated effluents under varying operating conditions, and estimated costs of constructing and operating a plant to handle 2,000,000 gallons a day.
The wastes from the plant, if discharged directly into the Delaware River through the proposed Outfall, would enter Zone 3. All sewage and industrial waetes in this zone are required to be treated to meet the following minimum requirements:
Zone 3. 1. Such effluent shall be free of noticeable Company, Borough floating solids, oil or grease, Of Eddystone, Pa*, whose and substantially free of wastes are discharged into both suspended solids and the tidal waters of the Delasleek. 2. Such effluent shall be sufficiently free of turbidity that it ware River below the city of Philadelphia, Pd. in the~ water of the Delaware The Sanitary Water Board of the ~ ~ of pennsyl- ~ will not cause ~ substantial turbidity ~ ~ River after dispersion in the water of the river. vania had directed the company to discontinue the discharge of 3. Such effluentshall show a reduction of at least fifty-five these wastes or to submit to the board a report and detailedplans ( 5 5 ) per cent of the total suspended solids and a reduction of not less than thirty-five ( 3 5 ) per cent of the biochemical demand. for works to provide treatment for the reduction of pollution. [It is the intent of this requirement to restore the dissolved oxyThe tests described herein ere carried out to determine appligen content of the river water in this zone to at least fifty (50) per cable methods of treatment and basic design data for treatment centsaturation. T~ accomplish this, it may be necessary in the works. case of certain wastes to obtain reductions greater than those required under this item.] REQUIREMENTS OF THE S A N I T A R Y W A T E R B O A R D 4. Such effluent, if i t be discharged within two miles of a publie waterworks intake or kithin prejudicial influence thereof, shall The of the Interstate Commission on the Delau,are a t all times be effectively treated with a germicide. River Bmin for sewage, industrial wastes, or other polluting mat5 . Such effluent shall be sufficiently free of acids, alkalies, and tei discharged into the waters of the Delaware River Basin are other toxic or deleterious substances, that it will not create a menace to the public health through the use of the waters of the those adopted by the Sanitary JfTater Board. This river basin is Delaware River for public water supplies, or render such waters divided into four zones, and the requirements set for each unfit for industrial and other purposes; or cause the water of the depend upon “location, size, character, flow, and many varied neiaware ~i~~~ to be harmful to fish life. uses of the waters.” 6. Such effluent shall be practically free of substances capable dz
~
