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 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
~
622
INDUSTRIAL AND ENGINEERING CHEMISTRY Table
I.
Results of Analyses of Composite Samples of D a y Flow of Combined Wastes
8:OO A . M - 1o:oo A . M . - 1 2 : 0 0 M - 2:00 %ai.- 4 : O O r h i . 1o:oo A . X . 12:OON. 2:ooP . Y . 4:OO P.M. 6 : 00 I' \[. Physical examination" Color Red-brown 3 Rrown 3 Brown-red 4 Brown 3 Red-brown 4 Odor Soapy 3 Soapy 3 Soapy 3 Soapy 4 Soapy 3 Suspended matter 3 3 3 2 3 Turbidity 4 4 4 3 4 Chemical examinationh pH index 11.30 11.36 11.45 11.53 11.20 Alkalinity as CaCOi Total 492 458 692 744 514 Hydroxide 65 110 272 144 42 Carbonate 424 348 120 600 472 Bicarbonate 0 0 0 0 0 Residue oil evaporation Total 1362 It68 1688 1600 1982 Loss o n ienition 796 674 1046 814 QS4 Fixed resydue 366 494 642 786 598 Suspended solids Total 84 94 Loss on ignition 52 90 rixed residue 32 4 Turbidity 131 213 Oxygen consumed, total 340 ,520 B O.D. (5-clay, 20' C ) , t o t a l 213 145 '2 1 yery slight; 2 slight; 3 diitinct: 4 decided, 5 extreme. b A11 chemical results in parts per million excen't pI-1 and settleable sulids.
Period of collection
of producing offensive tastes O r Odors i n I)ublic water supplies derived from the Delan-are River. PRELIMINARY INVESTIGATIONS
Composition of Wastes. The n-astes v o n which the tests byere lnade were warm, highly colored, and decidedly turbid-especially during the day-and had a strong soapy odor. The PI1 was in excess of 11.0. The residue on evaporation was about 1500 p,p.m,, the greater proportion of IYhich was mineral. Suspellded solids were low, being considerably less than 100 p.p.m. and amounting to about 0.05% by volume with 2-hour sedimentation. Organic matter, as measured by oxygen consumed, ranged from 50 to 250 p.p.m. and averaged about 125; and the 5-day B.O.D. averaged about 100 p.p.m. The wastes discharged a t night were considerably weaker than those discharged during the day. Represent'ative analyses of day and night samples collected a t 15-minute intervals and made into 2-hour composites are given in Tables I and 11. Laboratory Tests. Preliminary laboratory treatment tests Tvere made on composite samples of the plant wastes using sedimentation and chlorination, alum treatment n+th pH coiitrol, and precipitation with calcium chloride and carbon dioxide. It was found that the quantit,y of settleable solids in the wastes was so small that little could be accomplished by sedimentation alone. Although the wastes had a considerable chlorine demand, chlorination was ineffective in reducing organic matter measuretl as oxygen consunled or as B.O.D. The addit'ion of calcium chlo-
6:OO r x -
8:OO
P.M.
Purple-brown 4 Soapy 3 3 4
9.90 220 0 120 100 1282 906 376 88 83
ride and sufficierlt carbo11 &oxide to neutralize the carbonat,e LL1kalinity caused a fine gra11al:ir precipitate of calcium carbonatc i,o form which partially clarified the wastes, but the costs for chciiiicals were excessive for the results produccd. Adjustment. of the pH of tile wastes wit11 up to 1000 II.I,III. or sulfuric acid and the additioll of 3 to 15 grains per gallon or ~ 1 ~ : , 1 i iium sulfate produced good clarification and color remov;Ll arrti a reduction of 20 to 30% oi 13.0.1). The sludge produccci avo^aged about 2% by volume of t,21c total cornbined mastes. PILOT PLANT INVESTIGATION
Description ofYPilot Plant. Thc analyses and test.3 nia,de oti the composite samples of wastes furnished significant data f o r the design of the pilot, plant. "his plant esscntis'*y O f : An equalizing tank for equalizing t'he variations in composition of the wastes, having capacity for 2 hours' flow. A sulfuric acid mixing tank having a capacity for about 5 miiiUtes' flow for neut,ralizing the excessive alkalinity of the wastes. An alum mixing tank (flash mix) for mixing a solution of alum (sulfate of aluminum) wit,h t,he neutralized wastes for tre:itmeiit by chemical precipitat,ion. A flocculator to facilitate coagulation, having a capacity for 30 minutes' flow af the alum-treated wastes. A sedimentation tank or "thickener" for clarifying the chemically precipitat,ed wastes with provision for measurements and t,ests of the sludge b luding a filter leaf and a small sludge-d ~~
Table
Vol. 42, No. 4
~~
II. Results of Analyses of Composite Samples of Night Flow of Combined Wastes
Period of collection
8:OO
1O:OO r . v F.Ar.>I.
10:oo I'
12:oo inidnight
12:oo
midnight2:00 A.M.
P h sioal examination" 6olor Rronn 1 l-elloa. 4 Yellow 2 Odor Soapy 3 Soapy 2 Soapy 1 3 Suspended matter 2 I 4 Turbidity 3 2 Chemical examination!) p H index 9.35 9.7: 0.80 Blkalinity R S CaCO3 162 Total 140 136 40 48 Carbonate 64 Bicarbonate 112 02 72 Residue on eraporatiou Total 678 660 644 Loss o n ignition 452 344 342 Fixed residue 226 316 302 Suspended solids 65 15 12 Total Loss on ignition 49 13 8 2 6 4 Fixed residue 44 120 26 Turbidity 135 25$ Oxygen oonsumed, total 170 B.O.D. (5-day, 20" C.), total 00 47 49 a 1 very slight: 2 slight; 3 distinct: 4 decided; 5 extreme. b Parts per million except p H and settleable solids.
2 : 00 4:OO
A 51 A.M.
Pellou 3 Soapy 2 1
Yellow 3 Soapy 2
Gray 3 Musty 3
2
1 2
2 2
9.75
9 , 9.5
7.40
120
I70
66
44 76
80 I10
0
66
474 228 246
524 252 272
124G 540 706
9 7
24
2
27 24
J
2
19
28 43 15
13 82
57
10 96
67
s
April 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
A coke filter for treating the neutralized wastes. A high-rate trickling filter unit. The equalizing tank was approximately 5 feet square and 4 feet deep, providing a water depth of 3.25 feet below the 2-inch overflow to the drain. This volume of approximately 81.3 cubic feet was equivalent to a little over 2 hours’ flow at a rate of 5 gallons per minute. The capacity could be increased by raising the 2-inch overflow. The flow to be treated was taken off by a 0.75-inch pipe at a lower level to the sulfuric acid mixing tank. The sulfuric acid mixin tank, holding about 5 minutes’ flow for mixing sulfuric acid wit$ the wastes to be treated, was fed with a dilute sulfuric acid from a carboy through a 0.5-inch pipe. A pipe line from this mixing tank was provided for supplying neutralized wastes to the high-rate trickling filter. For chemical precipitation, the neutralized wastes in the sulfuric acid mixing tank were drawn to the alum mixing tank. where the desired amount of alum solution was added. After mixing, the alum-treated wastes were passed through a small Dorr flocculator and thickener. The flocculator was 1foot 10 inches wide, 10 feet long, and 2 feet deep, having a capacity of 150 gallons. The thickener was approximately 6 feet in diameter by 3 feet in side-wall depth, having a capacity of about 600 gallons. The high-rate trickling filter was designed so that either the effluent from the chemical precipitation tank or neutralized wastes could be applied to it. The wastes were pumped either from the chemical precipitation tank or the neutralizing tank to a storage tank having about 50-gallon capacity. A similar storage tank was provided for recirculated effluent from the secondary settling tank, of about 50-gallon capacity. The desired quantity of each could be drawn to a mixing tank and the mixture applied to the filter. A tipping bucket was provided for the distribution of the wastes on the surface of the filter, which in a large plant would generally be provided by a revolving distributor. The filter was about 2 feet in diameter and 6 feet deep, composed of crushed stone about 2.5 inches in size. Later, the filter was enclosed and heated with steam to accelerate the growth of the necessary oxidizing organisms because of the limited time available for the operation of the pilot plant. OPERATION OF PILOT PLANT
The pilot plant was operated continuously from the week ending September 25 until the week ending December 18, 1948. During this period, specific studies were made to determine the necessity of equalization and sedimentation of the combined wastes, efficiency of chemical treatment, efficiency of high-rate trickling filter, and possible sludge-handling and disposal methods. Because of lack of time and the fact that satisfactory results were obtained by the trickling filter, no tests were made on the coke filter. Sedimentation and Equalization. The wastes discharged from the plant change rapidly in charactcr and strength, including suspended solids content, alkalinity, pH, and temperature; therefore, it was found necessary to equalize these variations before treatment. Table I11 shows the gradual change in the alkalinity of the effluent from this tank after equalization. A small quantity of settleable solids was removed by this 2hour detention. The tank was unwatered weekly and the volume of sludge measured. The quantities of sludge produced are shown in Table IV. The quantity of sludge varied from 1000 to 2500 gallons per million gallons of wastes treated, and averaged 1600 gallons. A sample of the sludge collected during the week of October 18 to 23 was analyzed and found to contain 2.2% of dry solids, of which 63.6% was organic. A summary of the results of analyses of the composite samples of the equalizing tank influent and effluent is given in Table V. The 2-hour settling period accomplished little in purification of these wastes. The quantity of solids removed was practically nil. This was substantiated by the actual measurements of sludge removed weekly from the tank. Although equalization of the wastes was of little value in removing settleable solids, it was of great value in equalizing the strength of the wastes.
Table Time,
111.
Total Alkalinity of Equalizing Tank Effluent (October 18 and 19, 1948)
6:30 7:OO
P.P.M. 695 580 560
7:30
530
P.M.
6:OO
623
Time, AM.
l:oo 2:oo 3:OO
Time, A.M.
P.I’.,\I
180 160
10:30 11:oo 11:30
395 460
145
12:OO
P.P.M. 195
...
M.
4:OO
540
P.Y.
8:00 8:30 9:00 9:30
485 440 400 365 310 275 265 250
1O:OO
10:30
11:OO 12:OO
Table
IV.
5:OO
130 120 125 115 125 130 200 280
6:OO
7:OO
8:OO
8:30 9:oo 9:30 1O:OO
12:30 1:OO
1:30
2:OO 2:30 3:OO 3:30
4:OO
578 585 540 530 540 605 625 620
Quantities of Sludge Produced in Equalizing Tank Volume of Volume of
Period From To Oot. 11 Oct. 16 Oct. 18 Oct. 23 Oct. 25 Oct. 30 Nov. 6 Nov. 1 Nov. 8 Nov. 13 Nov. 20 Nov. 15 Nov. 22 Nov. 27 Deo. 4 Nov. 29
Operation, Hours 102 90 91 97 115 109 40 115
Waates Treated, Gal. 21,800 19,200 19,500
20,800 38,200 36,400 16,300 38,100
Sludge Produced, Gal. 23.4 23.4 31.2 31.2 93.6 62.4 15.6 78.0
Volume of Sludge,
% 0.11 0.12 0.16 0.15 0.25 0.17 0.10 0.21
Chemical Precipitation. Part of the pilot plant was operated from October 4 through November 24, using chemical coagulation and precipitation. The time covering these tests may be divided into four periods. During the first period, from October 4 through October 20, the plant was being tuned up and operated using sulfuric acid for p H control and aluminum sulfate, commonly called alum, as a coagulant. During the second period, from October 22 to November 9, the plant was operated using alum as a coagulant but without pH control. During the third period, November 9 to 22, inclusive, representative test runs were made using alum alone as a precipitant. The fourth and final period extended for 2 days, November 23 and 24, in which tests were made to determine whether plant efficiency, including costs of operation, could be improvedusing clay with the alum to assist flocculation. The results of the tests during the third period, given in Tables V1 and VII, represent the best obtained during any of the four operating periods and constitute the basis upon which estimates of efficiency and costs of a full-size treatment plant were made. During this third period, the wastes were treated with alum ranging from a minimum rate of 1310 pounds per million gallons to a maximum of 2470 pounds per million gallons, averaging 1780
Table
V.
Summary of A n a l ses of Equalizing Tank influent and Effluent Turbidity
Nov. 15-19 Influent Effluent NOV.22-24 Influent Effluent Nov. 30-Dec. Influent Effluent Dec. 6-10 Influent Effluent
pH
Oxygen Alka- Residue SusConB.O.D. linity, on Evap- pended sumed 5-?az: Total oration Solids (30 Min.) 20 Parts per Million
180
8.9 8.6
185 194
1143 1137
106 100
205 204
138 110
255 223 3 122 138
10.4 10.6
365 375
1302 1406
125 123
261 258
148 127
10.1 9.5
217 223
816 787
57 65
234 213
182 140
110 95
10.6 10.5
297 277
971 943
61 63
258 249
250 210
Av. Nov. 16-Deo. 10 Influent 167 1 0 . 0 9.8 Effluent 152
266 268
1058 1068
88 88
239 231
179 151
151
INDUSTRIAL AND ENGINEERING CHEMISTRY
624
Table
Date, Temp. of -->l(l'T1 Nov. Wastes, 1948 F. Lb./mg.
5 8 9
10 11 12
86 86 86 86 86 81
13
14 13 16 17 18 19
VI. Summary of Chemical Treatment Operation
(Period 3, November 5-22, 194gn) pII of Effluent Retention Period, EqualEqualFloccuCostb, izing I'loccuClariimng lator s/mg tank lator fier tank tank
-
AV.
2470 1310 1650 1075 1070 ]GOO . . I
37,0; 19 65 24.75 25.02 16.05 24.00
..
9.1
7.4
10.2 9.3 10.1
7.8
8 5
,.. ,. . . ,
0.6 0.6 0.6
...
2.1 1.7 1.8 1.9 1.8
, . .
1.9
0.6
1.8 1.9 1.8 1.8 1.8 1.8
0.6 0.6
b
-41uin at
9.0
9.2
... , . .
82 88 81 88 88
1400
Vol. 42, No. 4
2i:oo 2310 35.55 2030 30.45 2280 34.20 1720 25,80 .4v. 85 1780 26.70 a Including 2 days of Period 2,
9.8 10.1 9.0
9.6
B.G 9.6
7.1 8.2 8.6 6.6
...
Saturday Sunday 8.0 7.9
...
7.9 7.8 6 3 7.7
... . . ...
pountls per million gallons. This is cquivalcnt to about $2G 70 pcr million gallons for the cost of alum. Table VI1 shows that thclc was a noticeable improvcinent i n the appearance of the wastes after treatment. The decided rcdbiown color of the untreated wastes was reduced to a slight yellow tinge. The turbidity or milkinesb of the wastcs was reduced from 152 to 88 p.p.m., equivalent to a 42.8% reduction. The caibonate alkalinity was neutralized and the total allralinity icduced hy the action of alum from 236 to 133 p,p.m., a ieduction of 43.5%. The suspended solids weie reduced from 97 to 61 p.p.m., equivalent to 37.27,. This efiiciency would bc materially increased in a large plant, as the pilot p l m t clarifier did not operntr efficiently in these tests. The 13.0 13. \vas reduced fioin 146 to 30 p.p.m., or 45.2%. Sludge from Chemical Treatment. The quantity of sludge produced by chemical precipitation with alum, as determined by 2 hours' settling in Imhoff cones, ranged from 1.5 to 6.0% by volume, averaging 4.0%. This sludge contained about 1.0% ot dry solids by weight. On standing for 24 hours, thc volume was reduced to 2.1% and t h e solids increased to 1.9% by weight. Based on an estimated volume of wtstes of 2,000,000 gnllons per day, the total volume produced would amount to about 80,000 gallons of unconipacted sludge or 38,000 gallons of compacted sludge per day, containing about 6650 pounds of dry solids. Chemical Coagulation Tests, Using Clay and Alum. I t was pioposed that the addition of clay to the combined xastes befoie coagulation with alum might assist flocculation, tend t o reduce the color of the wastes, reduce the quantity of alum required, and concentlate the chemical precipitation sludge to be handled. 130th laboratory and pilot plant tests were made on the3e x-iastcs. Although laboratory tests indicated some advantage in t h e use of clay, pilot plant tests made during the day shifts only, .on Kovember 22 and 23, were not conclusive. For this reason, no further consideration was given to the ure of clay in the chemical treatment of combined wastes. Trickling Filter Tests. The pilot plant trickling filter w l t ~ placed in operation on October 14. I n order to seed the filter as rapidly as possible, unsettled sewage from the Eddystone Sewage Plant was recycled continuously through the filter. Part of the effluent was discarded every few days and replaced with fresh sewage. In order to accelerate the biological growth in the filter, the sewage was fortified with ammonium orthophosphate [( NHA)~HPOI] to furnish additional nutrients in the form of nitrogen and phosphates. During the seeding period, an eqliivalent of 10 p.p.m. of nitrogen and I1 p.p.m. of phosphorus was added. When a satisfactory growth on the filter media was observed, a portion of the recycled sewage was gradually replaced by increasing quantities of the combined wastes from the m l l , which
I . .
... ...
0.6 0.6
... ...
... , . .
0.6
0.6 0.6 0.6
iIours pilot plant Final Operasettling tion, tank IIours
2,5 2.3 2.3 2.3 2.3 2.3
... ...
24 22 24 24 24 21 0 0 22 24 23 21
2.3 2.3 2.4 2.3 2.3 19 2.3 22.4 530 per ton delivered.
had had the p H adjusted with sulfuric acid to a 6.0 to 8.0 rangc. The filter was operated with plant rvastes alone starting Kovemhcr 8. In order to determine the optimum operating conditions, it was necessary to run the filter a t various rates of dosing, using different rates of recirculation. The filter was operated continuously, c x e p t Saturdays and Sundays, from Sovember 8 through Dcccinber 17. On Saturdays and Sundays, when no mill wastes 1% ere produced, the filter effluent was recycled continuously. The titne over which the filter operated was subdivided into shorter periods wherein the ratio of recirculation, or the rate of filteration, was changed. Composite samples of the wastes and the effluents wcrc collected throughout the entire tcst run for analysis to dctcrmine the efficiency of tieatmcnt. A summary of the operation data for the diffeient periods is given in Table VIII. Period 6 is representative of the accomplishment by high-rate trickling filters. There had been some degradation in the effluent in the previous period, using a recirculation rate of 3 to I, so the rate was increased to 6.5 to 1, and the rate of application of wastes was reduced from 17,800,000 to 10,000,000 gallons per acre per day. During this period, all nutrient feeding was stopped. With these changes in operation, the effluent improved in appearance. The results are given in Table IX. The removal of suspended solids increased from 33 to an average of 4870, and the B.O.D. removal increased from 51 to 70%.
Table
VII. Efficiency of Chemical Treatment with A l u m Pilot Plant Tests
(November 9-18, 1948) Equalizing Tank Clarifier Sample Effluent Effluent Chemical used, alum, Ib./mg. 1780 Physical examination Yellow 2 Colora Red-brown 4 Odor" Resinous 3 Resinous 3 Suspended matter" 2 2 Turbidity, p.p.m. 152 87 Chemical examinationb p H index 8.50 7.43 -4lkalinity a s CaCOa 236 133 Total 0 0 Hydroxide 118 0 Carbonate Bicarbonate 11s 133 Residue on evaporation 1253 1280 Total Loss on ignition 405 380 Fixed residue 850 900 Suspended solids 61 97 Total 38 71 Loss on ignition 23 26 Fixed residue Oxygen consumed (30 min.), 208 189 total 13.O.D. (5-day, 20° C.), total 146 80 (6 2 slight; 3 distinct; 4 decided. b P.p.m. except pH.
..
Reduc. tion,
76
.. .. ..
0
42.8
.. 43.5
.. .. ..
-2.3 6.2 -5.9
37.2 46.5 11.5 9.2
45.2
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1950
Table
VIII. Operation Data, Hi h-Rate Trickling Filter, Pilot Plant Tests (average) 1 2
Period Volume, gal./day Wastes Recirculation Total applied Temn.. F. Wastes Final effluent Chemical added, Ib./nig. Sulfuric acid Diamrnonium phosphate Recirculation ratio Rate dosing, million gal./aore/day Wastes Total % reduction L B.O.D. k Suspended solids
3
4
5
6
336 666 1052 1080 1080 598 7522 5948 7200 3250 3240 3855 7858 6614 8252 4320 4320 4453 82 58 978 394 22.4
82 60
87
..
..
68
985 1963 1025 394 394 0 8.3 6.9 3.0
..
..
65
63
1673 1675 0 79 3.0 6.5
5.5 10.8 17.3 17.8 17.8 9.8 128.3 108.4 135.9 71.1 71.1 73.6
90 82
77 81
74 71
51 57
51 33
70 48
.~
Table
IX. Efficiency of High-Rate Trickling Filter, Pilot Plant Tests
(Period 6, December 13-17, 1948) Trickling ReducEqualizing Trickling tion, Filter Filter Tank Sample Efflucnt Influent Effluent % Chemicals used, Ib./mg. Diammonium phosphate None .. .. 1675 .. .. Sulfuric acid P h sical examinaton Brown 3 Gray-yellow 2 Gray-yellow 2 Zoior5 Odora Resinous 3 hlustv 3 Mustv 3 2 2 2 ii.5 98 81 75
Carbonate Bicarbonste Suspended solids Total Loss on ignition Fixed residue Settl.eabl? solids, % Nitrite rutrogen as N Nitrate nitrogen as N B.O.D. (5-day, 20’ C.), total
10.9
6.6
6.6
307 46 26 1 0
83 0 0 83
81
62 49 13 Trace
32 28 4 Trace 0.00 0.5
.. t .
168
53
0
0 81
I
.
73.7
.. ..
..
32 28 4 Trace 0.00 0.5
48.4 42.9 69.2
51
69.8
..
.. ..
quantity of sludge could be removed from the final tank and handled with the sludge produced in the equalizing tank. QUANTITY OF WASTES DISCHARGED
The volume of waste discharged could not be accurately determined from the quantity of water pumped, because of several factors, such as lack of knowledge of the efficiency of the pumps and of water uses which did not reach the wastes channels. This last use refers to filter washing, cloth drying, steam losses, water used in etching and machine shops, and sewage discharged t o t h e Eddystone sewerage system. The total volume of wastes discharged was determined from weir readings made on a weir constructed a t the outlet of the pipe line. All of the wastes sampled were 01a quality that would require treatment before discharge to the Delaware River. A considerable quantity of clean cooling water, amounting to 268,000 gallons per day, could be discharged to the river without treatment. However, i t was the author’s opinion that the costs of separation would be considerable and that tho separation would not greatly change the size of treatment plant nor reduce the cost of operation. TREATMENT PLANT PROJECTS
Two alternate projects for treatment of the wastes were studied. Plan I involved equalization, p H adjustment, chemical precipitation, and vacuum filtration of sludge. Plan I1 involved equalization, p H adjustment, treatment on high-rate trickling filters, and sludge dewatering on sludge beds. Both plans were based on treating an average flow of 2,00O,OO(p gallons per day with a maximum 8-hour average rate of 2,750,000 gallons per day. The estimated cost of construction together with annual operating charges based on prices of January I, 1949, is as follows:
1 very slight; 2 slight; 3 distinct; 4 decided: 5 extreme. h P. p. m. except pH.
a
Construrtion cost Operating cost, excluding fixed charges
Summary of Trickling-Filter Tests. Six test runs were made on the pilot plant high-rate trickling filter, using rates of application of wastes varying from 5,500,000 to 17,800,000 gallons per acre per day and an application of wastes and recirculated effluent ranging from 71,100,000 to 135,900,000 gallons per acre per day. T h e ratio of recirculated effluent to wastes varied from 3 to 22.4 times. A study of the results obtained indicates that in excess of 50% of the suspended solids and in excess of 60% of the B.O.D. can be removed from the combined wastes which have been conditioned with sulfuric acid by treatment on high-rate trickling filters, when the wastes and recirculated effluent are applied to the filter a t the rate of about 70,000,000 gallons per acre per day. With a recirculation ratio of about 4 to 1, this quantity is equivalent to an application of about 14,000,000 gallons per acre per day of the plant wastes. Sludge Produced by Trickling Filters. The suspended matter in the effluent from the trickling filters was very flocculent and did not settle readily. With a theoretical detention period in the h a 1 tank ranging from 26 to 50 minutes, depending upon the flow, only a small amount of solids settled; and it was not necessary to remove sludge from this tank throughout the entire test run. The volumetric determination of settleable solids in the final effluent showed a variation from a trace to 0.020/0, averaging about 0.01%. This is equivalent to only 200 gallons per day with a total flow of 2,000,000 gallons per day. Obviously, this small
625
Plan I, Chemical Treatment Plant $389,200 49,700
Plan 11, Hi h-Rate
f.Plant
Trick ’ ing Filter $434,400 20,000
The basis for costs under both projects is the same with the exception of maintenance charges. Under Plan I, these were estimated to he 2% of total construction costs as compared with 1% for Plan 11. This was due to the larger amount of mechanical equipment and the larger building which had to be maintained with the first plan. Comparison of Plans I and 11. Although the first cost of Plan I1 would he approximately $45,000 more than for Plan I, the net annual charges would be about $25,000 less. The difference in computed annual charges is due largely to increased labor and chemical costs. Plan I1 would involve much fewer complications of operation than Plan I. Furthermore, the sludge-disposal problem, were the second plan put into effect, would be much less serious than if the first plan were adopted. Consequently, it was recommended in the interest of economy and efficiency that the high-rate trickling filters be adopted for the treatment of the wastes, and plans for the full-scale treatment plant nrcl now being prepared by Albright & Friel, Inc. ACKNOWLEDGMENT
The author wishes to acknowledge the cooperation and assistance of Francis s. Friel and the staff of Albright & Friel, Inc., and of Frank Bromley, vice president of the Eddystone Manufacturing Company, in this study. R ~ C E I V IDeoember D 12, 1949.
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