I N D U S T R I A L A N D ENGINEERING CHEXISTRY
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FINAL
TOTAL SOLIDS
ORGANIC MATTER IN SOLIDS
I !
Per cent Per cent Per cent Per cent Per cent Per cent
Diminished pressure Atmospheric pressure Pressure a
7.5 7.4 7.5
i
6.47
4.72
27.0
52.5
41.9
42.0
6.47 6.47
4.96 4.73
23.0 27.0
52.5 52.5
43.2 42.6
37.0 40.0
Reduction of organic solids is on basis of fresh organic solids.
Conclusions
1-The incubation of a 2: 1 mixture of fresh and Imhoff sludges under pressures of 0.6,1.0, and 1.8 atmospheres gave a completed period of digestion comparable for all three conditions as determined by methane production and the reduction of organic matter. This was 7 weeks. The period for 85 per cent completion of digestion, based on methane production, was 37 days for diminished pressure, 40 days for atmospheric pressure, and 42 days for a pressure of 1.8 atmospheres, an indicated slight advantage for diminished pressure and a disadvantage for pressure as compared with normal conditions.
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2-Total gas production for some time prior to, and subsequent to, the middle point of digestion showed consistently different values for the different experiments, being greatest for decreased and least for increased pressure. If these differences could be adjusted for loss of gas due to the different pressure-solubility conditions, they would not be so great nor would they be significant of more than slight differences in the rates of digestion. 3-Methane production throughout was nearly parallel for the reduced and atmospheric pressure experiments. It was lower for the pressure experiment until the latter part of the digestion. This may have been due to an unfavorable influence upon the chemical environment by the entrained gases or to the inability of the bacteria to reach digestible solids by reason of the solids being surrounded by a barrier of gas bubbles. 4-As judged by the total period required for sludge digestion, there was no significant difference for any of the experiments. Therefore, devices aiming to establish pressures unusual in practice would presumably not shorten the digestion time. &The use of deep tanks for digestion of sludge may have certain advantages in operation. It probably has no disadvantage on the ground of the increased pressures a t which digestion must proceed.
Chemical and Biological Correlations in a Polluted Stream’,’ Willem Rudolfs NEW
JERSEY
AGRICULTURAL EXPERIMEXT S T A T l O N , NEW BRUNSWICK. N. 1.
The water of the Raritan River system in New Jersey and low mineral content place URING 1927 a study is in its natural condition admirably fit for potable and them definitely among the was made of the polluindustrial purposes. Unfortunately the lower section better waters of the United tion conditions in the of the river is heavily polluted. The studies conducted States for industrial use.” lower Raritan River and its show an apparent direct relation between the amounts The lower Raritan River is tributaries. The s t u d y exof ammonia present and the biochemical oxygen depolluted by the raw sewage of tended over one year and inmand of the river water. Oxygen depletion was far about 100,000 people and by cluded all seasons. greater in summer than in winter. The effect of two the industrial wastes of about The Raritan River system small dams upon the self-purification of the river 85,000 population equivalent. is the largest in New Jersey, is considerable. There was a direct relation between I n addition the effluent from except the Delaware. The B. 0. D., bacteria, and plankton. The highest number the Joint Plainfield Sewage tributaries do not combine of B. coli recorded was 11,000 per cubic centimeter Disposal Plant, treating the until they reach points within found opposite a bathing beach. During the summer waste of about 50,000 people, 7 miles of tide water. The months the average number of B . coli at this point was is discharged into a brook and whole Raritan drainage area 3240 per cubic centimeter. The relation between reaches the Raritan in about is 1105 square miles. The rainfall and oxygen saturation is pointed out. an hour. There is only one upper part of the drainage s e p t i c t a n k , treating the svstem lies in the hills and the -* - physiography of the territory changes until the lower part of sewage of a small borough, in the whole region. the Raritan runs through marshes into the Raritan Bay. Discharge Testing Procedure Collins and Howard3 state, in a paper on the surface waters in New Jersey, that “the river waters of New Jersey do not Discharge measurements for the years 1924-1927, inclusive, change in composition so much as many other waters in the United States.” Disregarding pollution and on the basis were supplied by the courtesy of 0. W. Hartwell, district of their chemical analyses, these authors conclude that the engineer, U. S. Geological Survey, Trenton, N. J. There were twelve sampling stations established, located waters of the Raritan basin with “their comparative softness as far as practicable in such a way that large sewer outfalls 1 Presented under the title “Some Results Obtained in Raritan River and the mouths of the larger tributaries had no disturbing Pollution Studies” before the Division of Water, Sewage, and Sanitation influence on the samples. Chemistry at the 76th Meeting of the American Chemical Society, SwampScott, Mass., September 10 to 14, 1928. The chemical analyses performed consisted of determina1 Paper 75, Department of Water Supplies and Sewage Disposal. tions of pH values, alkalinity, chlorides, ammonia, nitrites, 8 Collins and Howard, U. S. Geol. Survey, Water-Supply Paper 696-E nitrates, suspended solids, ash, dissolved oxygen, and 5-day (1927).
D
~
March, 1929
I N D U S T R I A L A N D ENGINEERING CHEkfISTRY
257
months the total discharge of the river was 40 per cent higher than the average for the five preceding years. The effect of re-aeration caused by two small dams is striking. Dam I is about 4 feet high and situated below a town discharging its sewage and factory wastes untreated into the river. Dam I1 is about 6 feet high and arrests the downward trend of the oxygen saturation curve still more. Up to sampling point 8 the river is shallow and not navigable. This shallowness would tend to facilitate re-aeration, but the pollution is such that self-purification of the river is slight except where these dams cross the river. BACTERIA AND PLANKTON-Agar plate Counts were made for total bacteria and the numbers of B. coli organisms determined. From a pollution standpoint we were more interested in the colon organisms than in total organisms, and especially in those of fecal origin. The average 1;'I / I yearly numbers of B. coli are plotted in Figure 3. i Figure 1-Average Results for Year The curve has the same general shape as those for Obtained a t Different Sampling Station: 2 A 4' a' e ' o . I 1 I1 I~ 1 0 B. 0. D. and ammonia curves, except that the along t h e River D.nplliy *t.tIrnn. effect of the dams is again emphasized. The averFigure 2-Relation between Yearly and Summer Averages of Percentage age numbers for the summer months were considerbiochemical o x y g e n demand. Oxygen Saturation of River Water ably higher. The lowest number recorded in any Bacteriological tests4 were made for total organisms and B. coli, while the plankton determina- one sample was 1 p& cubic centimeter of water and the highest tions6 consisted of identification of types or species and their number was 11,000 per cubic centimeter. At the point where greatest pollution occurred the lowest number recorded in midenumeration.
1
I
'I
Results
In order to obtain a picture of the average yearly
8. soli per ce.
Pellullon organiens (protax-) In hundred' per Inter.
d
2200
/I
-
3. The h s t part on the curve represents a sampling point several miles above the town of Raritan, where the contributing population is small and the river is but slightly polluted. The last point on the curve is for samples taken a t the Victory Bridge a t Perth Amboy, just about a t the mouth of the river. Figure 1 shows the increase in biochemical oxygen demand and ammonia present in the river. The density of pollution increases until a point is reached about half a mile below the town of New Brunswick, which has a population of about 50,000 (including the borough of Highland Park). The raDid dror, of B. 0. is due iothe tide water, Figure 3-Relation between Numbers of B. coli and Numbers D. and NH8-N-after this Organisms a t Different Sampling Stations which reaches about 2 miles above New Brunswick. Attention is drawn to the relation between KH3-N and B. 0. D. results. With the increase of from 2 to 4.5 p. p. m. B. 0. D. the ammonia increases from 0.05 to 0.175 p. p. m., or 0.05 12 ' , p. p. m. NH3 for each 1p. p. m. B. 0. D. The question might he raised whether the difference between the two determin Rt'ions observed below 2 p. p. m. B. 0. D. is due to the initial or purely chemical oxygen demand included in the readings. OXYGENDEPLETIOK-The yearly and summer averages of oxygen saturation are given in Figure 2. The percentages of oxygen saturation vary rapidly in this comparatively short stretch of river. The yearly average shows a drop from 89 n per cent saturation to BO, while the change during the summer I 70 months (June to September) is from 82 per cent, where the river is but slightly polluted, to 41 per cent helow New Brunsea . wick. There was no absolute depletion recorded during the summer, the lowest figures obtained being 26 per cent satura-I tion. It may be stated here that during these summer dl I I I I I
- (a
- 30 - 20 - 10 a
of Pollutional
I
I
I
In
June 7
Made by H. Heukelekian, Department of Water and Sewage. Made by J. B. Lackey, Department of Water and Sewage.
9
Figure 4-Relation
11
13
13
17
19
50
I 21
between Rainfall and Oxygen Saturation in River Water
INDUSTRIAL AND ENGINEERING CHEMISTRY
258
winter was 110 per cubic centimeter. The yearly average for this point was 2280, and for the summer months 3240, B. coli per cubic centimeter. This sampling point was located opposite a bathing beach where hundreds of people seek recreation in swimming during the warmer months of the year. It is evident from the results that the Raritan River is unfit for swimming purposes, even at places where the pollution is only slight. From ten to twelve places are used for this purpose, however. Swimming in polluted rivers, especially in the neighborhood of the larger cities, continues in spite of the danger. The boards of health of a number of states have made strict requirements for pool and outdoor bathing. The rules are often so strict that but few rivers and water courses near the larger cities could be used if the rules were enforced. The most lenient standard set for bathing beaches in this country is set by the former health commissioner of the city of New York, who allowed 25 to 30 B. coli per cubic centimeter before the bathing beaches are condemned. Professor Winslow6 suggests 10 B. coli per cubic centimeter instead of the more rigid requirements of the health boards and the 8
Winslow, A m . J . H y g . , 8 (January, 1928).
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U. S. Public Health Service. The question might be raised whether a policy followed by New York or that suggested by Winslow is not better than strict requirements which in the large number of cases cannot be met. Figure 3 shows also the numbers of pollution organisms (green flagellates) per liter of water. The relation between the numbers of B. coli and the numbers of these protozoa, known to be characteristic of polluted water, is rather striking. RAINFALLAND OXYGEN SATURATION-The percentage oxygen saturation of river water changes from day to day. One of the most important factors seems to be changes in discharge caused by rainfall. The results from a detailed study are plotted in Figure 4. As soon as the rainfall increases the oxygen saturation of the water increases. It should be remembered that the oxygen saturation figures are corrected for changes in temperature. The detailed study from which the figures are taken for the construction of the graphs was made while samples were taken every hour during a little more than a week. If the results are plotted on an hourly basis the relation between rainfall and changes in oxygen saturation are even more apparent.
Sludge Digestion and pH Control' H. W. Clark2 and George 0. Adams' MASSACHUSETTS DEPARTMENT OF PUBLIC HEALTH, STATE HOUSE,BOSTON,MASS.
When sludge from the sewage of different municipaliExperiments with Lawrence H E pH control of sludge ties is digested under identical conditions, the pH Sewage and Sludge digestion has been Under investigation for necessary for the best digestion of each sludge may vary. I n the first experiments the several yearsat the Lawrence This is due t o the difference inherent in the organic bottles, in each of a and mineral contents of each; that is, their chemical Experiment Station of the liter of sludge was beMassachusetts Department composition varies. Raising the PH by the addition fore filling with sewage, were of Public Health. Experiof calcium carbonate is an aid in accelerating digestion operated as follows: merits have been conducted in in certain instances but the sludge of other municipalities has an available alkalinity that makes such No. 1-A control. receptacles of v a r i o u s sizes addition unnecessary and there is practically always No. %pH adjusted by adranging from gallon bottles, dition of small amounts of preof which many have been a slow accumulation of lime in the sludge, for Organic cipitated calcium operated, to experimental Immatters are destroyed by bacterial digestion but the No. 3 S m a l l amounts of the hofftankshavingacapacityof lime remains. Organic acids resulting from the deacetic acid were added daily to keep the pH around6.0. from 300 to 1250 gallons each. composition of sludge may, while causing low pH, be No. &The sludge and sewI n the Imhoff tanks and in all beneficial t o digestion. age were given an additional the bottles operated during degree of hardness by stirring the first of these experiments, only Lawrence sewage and with precipitated calcium carbonate. i?ganed the equivalent of 1 Per cent of strong WoolLawrence sludge were used. During the past year sludge from other municipalities in Massachusetts has also been No. contained per cent of strong paper-mill waste studied. Up to the present time about thirty-five sludge- liquor. digestion bottles and seven Imhoff tanks have been operated. NO. 7-sodium nitrate equivalent to 2.5 parts in 100,000 parts These digestions in gallon bottles were made as follows: of nitrogen was added. No. 8-200 cc. of a well-nitrified sewage filter effluent wefe The bottles were fitted with rubber stoppers through which passed three glass tubes. One of these tubes with a funnel a t ad$:. was in all respects a duplicate of No. except it was its upper end and its lower end just above the sludge in the operatedat a low temperature-500 F. c.~e bottle was used to add sewage to the bottle. The second tube, reaching about half way down the bottle, was bent a t Gas analyses were made frequently enough and of such its upper end in Order to liquid to a beaker placed volumes of accumulated gas as to represent closely the total beside the bottle. As gas was evolved and collected in the gas produced. Fermentation began immediately in all the upper part of the bottle an equivalent volume of liquid Was bottles and the rate of production of total gas is shown in forced through this tube. The third tube, which reached just Table 111,in which the carbon dioxide dissolved in the sewage through the stopper, was closed with a pinchcock and used and sludge is included. Frequently this carbon dioxide in to deliver gas from the bottles. solution was as great as that set free and present in the total 1 Presented before the Division of Water. Sewaee. - . and Sanitation at volume of gas above the liauid. the 76th Meeting of the American Chemical Society, Swampscott, Mass., REs~~Ts-Spaceforbids giving all the results of each gas September 10 to 14,1928. analysis, hence only the volumes of carbon dioxide and meth* Chief chemist, Massachusetts Department of Public Health. ane produced are shown in Tables I to IV (from Report of * Chemist at the Lawrence Experiment Station.
T
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