February, 1931
I,VDUSTRIAL AND ENGINEE'RIATG CHEMISTRY
tion in concentration was made in order to obtain a less alkaline water. The pH of the 300 p. p. m. sodium bicarbonate was usually between 7.7 and 8.3. The results of approximately 1900 determinations of p H in the Illinois River laboratories of the Sanitary District of Chicago for 1929 are shown in Figure 8. These curves indicate that, with the exception of Lockport and Morris, the pH generally varied between 7.5 and 8.2. In view of this rather alkaline reaction of the river water it has been concluded that the use of the sodium bicarbonate water is preferable to that of distilled or tap water. Proposed improvement of this synthetic water has been discussed elsewhere ( 2 ) . The selection of the dilution water for B. 0. D. tests in stream-pollution studies depends upon many local conditions, particularly the suitability of the available tap water. Where such
213
waters vary or give high blanks or cannot be stabilized successfully, it is our belief that synthetic water is preferable. I n the course of the work on the Illinois River various types of incubators have been studied. The general practice is to use an air-tempered incubator, but very good results have been obtained by G. R. Barnett a t the Peoria laboratory with a water bath thermostatically controlled. The results indicate that such a water bath can be controlled much more accurately than an air incubator of the type used by the writers and the cost of operation is less. Literature Cited (1) Hoskins, Ruchhoft, and Williams, U. S. Pub. Health Service, Bull. 171 (1927). (2) Mohlman, Sewage TVoorks J., 2, 375 (1930). (3) Mohlman, Edwards, and Swope, IND. END.CHEM.,19, 242 (1928).
__--
Some Interrelationships of Plankton and Bacteria in Natural Purification of Polluted Water' C. T. Butterfield and W. C. Purdy U. S. PUBLIC HEALTH SERVICE,CINCINNATI, Oar0
Based on the results of a series of biological and A preceding paper ( 1 ) has HE abstraction of dischemical experiments, the theory is advanced that the described the p r e p a r a t i o n solved o x y g e n froni chief function of certain plankton in the biochemical and characteristics of a simple polluted water during oxidation process is to keep the bacterial population r e p r o d u c i b l e dextrose-pep the natural purification procreduced below the saturation point and thus to provide tone solution. Unless otheress is a well-known phenome conditions suitable for continuous bacterial multiwise stated, this standard non. It is also well known plication and as a result provide for more complete m e d i u m was used in the that the amount of dissolved oxidation. studies here reported. oxygen used up is definitely Support is given to this theory of the function of the related to the amount of polOxygen Depletion in Abplankton by the results obtained in experiments where lution present. While these sence of All Living the limiting numbers of bacteria were reduced by facts in regard to the natuOrganisms physical and by chemical means. Such reductions in ral purification of polluted bacterial numbers were invariably followed by renewed Suitable tests were made water are definitely known, bacterial multiplication and oxidation. to determine the extent of the mechanism by which the o x y g e n d e p l e t i o n in the oxidation is accomplished is only assumed. For instance, if a portion of polluted water is dilute medium: (a) in the absence of all biological forms, examined many bacteria and plankton are found. If all of and (b) in the presence of dead cells of B. aerogenes. No these organisms are killed or removed from the water, oxida- appreciable oxygen depletions were observed in 10 days. tion ceases. The part that each of these biological factors Oxygen Depletion in Presence of Bacteria Only plays in the progress of events, together with their interreactions, constitute the subject of this study. Studies were carried on with B. aerogenes and with bacteria Purdy and Butterfield (S), in their study on the effect of plankton animals upon bacterial death rates, showed quite other than B. aerogenes. All were in pure culture. The clearly that certain of the protozoa are responsible for the major portion of the work was done with B. aerogenes in an destruction of large number of bacteria in the natural puri- attempt to establish definitely the deoxidizing properties of fication process. Unfortunately their bacteria and plankton this organism under standard conditions, so that, in turn, results were not complemented with collateral data on the the effect and the function of the plankton, growing in pure chemical changes produced. culture and in combination with B. aerogenes, might also be I n the present work preliminary studies were made with definitely established. heterogeneous combinations of bacteria and plankton. With B. aerogenes, procedure was as follows: The dilute These studies, while instructive, presented too many vari- standard medium was prepared in 10-liter quantities, and ables to be of real value. sterilized. After cooling and vigorous agitation, the medium Further studies, with adequate control, were next under- was inoculated with B. aerogenes. The temperature of the taken t o determine oxygen depletion in a medium containing carboy of inoculated medium was next adjusted to approxino living organisms; oxygen depletion when bacteria only are mately 20 O C., the contents thoroughly mixed, then allowed present, in pure culture and in mixed culture; oxygen de- to stand quiescent a few minutes to permit escape of enpletion when no bacteria, but plankton only, are present; and trained air. The inoculated medium was siphoned to sterile oxygen depletion when bacteria and plankton are both pres- dissolved oxygen bottles with elaborate precautions to preent, in pure culture and in mixed culture. vent contamination. The dissolved oxygen bottles filled in this procedure were Received September 20, 1930. Presented before the Division of numbered in consecutive order. Initial determinations were Water, Sewage, and Sanitation Chemistry at the 80th Meeting of the American Chemical Society, Cincinnati, Ohio, September 8 to 12, 1930. made of the bacterial and dissolved oxygen contents of some
ILVD USTRIAL A S D ENGISEERISG CHEMISTRY
214 Table I-Bacterial
TIME
I
Counts and Oxygen Depletions Observed in Dilute Dextrose-Peptone Solution Inoculated with Pure Culture of Bacteria EXPERIVE~T AVERAGE
4
5
7
6
8
14
0
48,000
4,260,000
88,000
239,000
1,000,000
1
2,700,000
11,400,000
5,000,000
6,650,000
6,700,000
2
6,200,000
12,300,000
7,800,000
6,350,000
7,500,000
3
6,800,000
13,400,000
6,200,000
7,000,000
6,900,000
4
6,500,000
12,900,000~
7,000,000
6,100,000
6,750,000
6,400,000 6,200,000 6,300,000
5
6,100,000
12,400,000
5,600,000
5,800,000
6,700,000
4,750,000
6
6,250,000
12,700,000
6,650,000
6,300,000
6,060,000
4,480,000a
7 8 10 l5b
7,800,000 5,450,000 5,800,000
10,800,000 11,200,000 10,800,000 7.650.000
5,800,000 5,700,000 5,800,000 4.200.000
5,650,000 6,900,000 6,900,000 4.150.000
7,300,000 6,550,000 6,800,000 4.350.000
4,200,000 6,300,000 4,900,000 4.100 000
P. p . m.
P. p . m.
p.p.m.
P.p.m.
P.p.m.
P.P.m.
2.33
2.57
2.49
2.06 1.92 2.485
37,700 5,400,000 5,600,000 5,900,000"
1
1.96
..
2
3.07
2.83
2.50
2.75
2.44
3
2.63
2.94
2.58
2.61
2.54
4
2.76
3 , OS"
2.50
2.91
2.74
3.01 2.94 2.95
2.79
3.23
2.56
3.13
3.69
3.13
2.81
3.64
2.89
3.20
2.53
3 . 17a
1
16
17
640,000 5,200,000 6,800,000 6,800,000 6,550,000 6,290,000"
5,800,000 6,000,000 7,050,000 6,600,000 6,500,000 5,900,000 6,500,000 6,300,000 6,170,000 6,200,000
370,000 417,000 7,200,000 6,700,000 8,250,000 9,050,000 8,800,000 6,700,000 9,100,000
85,000 84,000 4,100,000 4,500,000 7,400,000 7,200,000 7,800,000 7,700.000 7,160,000a
753,000 6,130,000 7,630,000 7,600,000 7,410,000
6,450,000 6,700,000 8,900,000
7,150,000
9,000,000 7,900,000 7,500,000 6,100,000
6,600,000 8,160,000 7,000,000
7,060,000 7,160,000 6,850.000 5,250,000b
P.9.m.
P.p.m.
P.p.m.
P. p . m
2.05 1,88 3.12 2.28 2.56a
2.83 2.06 3.17 2.63 2.69 2.47 2.64
2.23 2.09 3.30 3.30 3.35 3.36 3.45a
2 24
3.01
3.58 3.50 3.63
2.:
9,600,000 9,300,000a
7,430,000
2 77
1 75 I 83
L.0,
2.45 2.30
?.'2
2.90a
2 30 2 94 3 02 2 86
2 3 3 4
3.02
L 67
7
2 80
3 2 2 3
15b Q
15
aeronenes PER cc.
A-E
Da>s -
6
Vol. 23, Xo. 2
21 80 89 01
2 2 2 3
55 56 66 32
2 2 3 3
86 89 64 48
3 17 3 03 3 41 2 32
3 3 3 3
21 23 08 37
79 04 00 00
2 95 3 70
3 16 3 19b
Calculated figure; mean of preceding and following results.
b Includes results obtained a t 1 3 t o 16 days.
Table 11-Colpidium Counts and Oxygen Depletions Observed in Dextrose-Peptone Solutions Inoculated with Colpidium i n Pure Bacteria-Free Culture TIME
OF
INCUBATION
CONCENTRATIONCOLPIDIUM PER cc.
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