February, 1930
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y Literature Cited
(1) Barker, University of Missouri, B d l . S4, No. 26 (1923). (2) Doerner, Bur. Mines, Repls. of Iwestigations SETS (1928). (8) Fleck and Haldane, U. S. Patent 1,577,217 (1926). (4) Kithil and Davis, Bur. Mines, Bull. 10s (1917).
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(5) Kunkle, Eng. Mining J . Press, 114, 503 (1922). ( 6 ) McCoy, U. S. Patent, 1,154,230 (1915). (7) Parsons, Moore, Lind, and Schaefer, Bur. Mines, Bull. 104 (1916). (8) Spun and Wormser, “Marketing of Metals and Minerals,” New York, 1925. (9) Vogt, U. S. Patent 1,429,550.
Pollution Studies of the Upper Mississippi River’ F. L. Woodward MIXNESOTA DEPARTMENT O F HEALTII, ?IlIKNEAPOLIS,
Mlh‘S.
This paper covers briefly the activities of the Minneing Minneapolis is fairly well HE pollution of the upper Mississippi River, sota State Board of Health and cooperating departrecovered from any great particularly the section ments in studying the pollution problem of the Misl o a d s of pollution. Soon sissippi River from Minneapolis and St. Paul, Minn., after entering the Twin City below the Twin Cities, has to La Crosse, Wis., a distance of about 160 miles. It a r e a t h e r i v e r shows t h e longbeena subject of discuswas found that conditions of pollution are evident effects of the sewage and insion and complaint, but not until recently has it been during the winter time as far down stream as the outlet dustrial wastes discharged &le to make any comprehenof Lake Pepin, a distance of about 100 miles. Under into it. Visible evidence of summer conditions the pollution is quite pronounced this pollution may be found sive study of the situation. for a distance of 50 miles or During the period from June, at the head of Lake Pepin 70 miles below Minneapolis, but recovery is practically complete at the outlet of more down the river. Other 1926, to August, 1927, H. R. Crohurst, sanitary engineer the lake. The changes in the oxygen balance at various evidences of the extent of points in the stream at different seasons are illustrated pollution are odors produced of the U. S. public Health by means of charts. During the summer, odors are by the d e c o m p o s i t i o n of Service, conductedan investiproduced by the decomposition of organic matter in sewage and wastes and the gation of the pollution of the the pool above the Twin City Lock and Dam. Another absence of fish life in the secMississippi River and its dam is being constructed at Hastings 30 miles downtion of the river immediately tributaries from Minneapolis stream, which is expected to bring about similar condibelow the Twin Cities. to Winone, a distance of a p p r o x i m a t e l y 137 miles. tions in the river through St. Paul and South St. Paul. T h e Mississippi River A tentative classification, from a pollution standpoint, enters Minneapolis a t CamDuring the same period a study of fish life in that of the river below Minneapolis is given. den a t an elevation of about section of the river was made 802 feet above s e a level. by A. H. Wiebe, biologist of the U. S. Bureau of Fisheries. Near the business center of Minneapolis the river passes over It is fortunate that this work was done a t a time when St. Anthony Falls, dropping about 70 feet t o an elevation the discharge of the river was less than it had been for of 728. About 6 miles below St. Anthony Falls is located many years and conditions of pollution were consequently the Twin City Lock and Dam, where the river again drops more pronounced than they are during ordinary stages of the 33 feet to an elevation of 690. This dam has created a pool river. of relatively foul water extending about 5 miles upstream. The Metropolitan Drainage Commission of Minneapolis All but one of the sewers of the Minneapolis system and and St. Paul was created by an act of the Minnesota Legis- eleven of those of the St. Paul system discharge into the river lature in 1927. The commission immediately began its work above this dam. As a result, large quantities of suspended of studying the subject of sewage disposal for the Twin Cities. material are deposited in the pool. These deposits give In order that the commission might have a basis for its pro- rise to unsatisfactory conditions, especially in the summer gram, the Minnesota State Board of Health was asked to when the river discharge is low and the water temperature make a classification of the river below the Twin Cities. is high. Mr. Crohurst states in the preliminary report of This necessitated the collection of additional information his work on the Mississippi that indications of septic conbefore such a classification could be made. Therefore, the ditions are likely to be found in the pool above the Twin Minnesota State Board of Health in collaboration with the City Lock and Dam during the summer whenever the flow Minnesota Department of Conservation, the Wisconsin State of the river is less than 5000 cubic feet per second. This Board of Health, and the Metropolitan Drainage Commission, statement is corroborated by observations made in 1928. conducted an investigation during 1928 covering the MissisA few miles below the Twin City Lock and Dam the Mississippi River from Minneapolis to the southern boundary of sippi is joined by the Minnesota, a river which, because of its Minnesota, treating the various phases of the pollution low summer discharge, does little to relieve conditions in the problem. Mississippi. Below this point the river receives additional sewage and industrial wastes from St. Paul, South St. Paul, Pollution Conditions between Twin Cities and La Crosse and Newport. At Hastings, about 30 miles below the Twin The Mississippi River rises among the lakes of northern City Lock and Dam, another dam is being constructed as an Minnesota and flows a distance of about 530 miles before aid to navigation. This dam will create a pool extending upentering the Twin City area. The cities and towns discharg- stream to the Twin City Lock and Dam, and it is expected ing sewage and wastes into this stretch of the river are rela- that the conditions found in the pool above the present dam tively small and far apart, so that the water in the river enter- will be duplicated in the pool through - St. Paul and South St. Paul. 1 Received October 12, 1929. Presented before the Division of Water, A short distance below Hastings the St. Croix River enters Sewage, and Sanitation Chemistry at the 78th Meeting of the American Chemical Society, Minneapolis, Minn., September 9 to 13, 1929. the Mississippi. This is a relatively clean stream and,the
T
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I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Vol. 22, No. 2
M A P OF MlSSlSSlPPl RIVER
% D€TWEEN MINNEAPOLIS
6 LA CROSSE
SMOWING LOCATION OF
SAMPLING POINTS
Chart 1
discharge is sufficient to improve conditions in the Mississippi appreciably. However, for the next 30 miles, until the river enters Lake Pepin just below Red Wing, the pollution is still quite evident. Lake Pepin is formed by the widening of the Mississippi River. The lake is about 25 miles long and from 1 to 3 miles wide. The average depth is 25 to 35 feet. This lake serves very effectively as a settling basin, where the silt and suspended materials carried by the river are allowed to deposit on the bottom. The water leaving the lake is much improved as compared with its condition on entering the lake. Immediately below Lake Pepin the Mississippi is joined by the Chippewa River from the Wisconsin side. The Chippewa has a comparatively high discharge during most seasons and does not exert any great polluting effect on the Mississippi. Below this point the Mississippi receives sewage and waste from Wabasha, Minn.; Fountain City, Wis.; Winona, Minn.; and La Crosse, Wis., in the order named. It is also joined by several minor tributaries, which have little effect upon it. While conditions of pollution are quite marked below Winona and La Crosse, the volume of hater and ,8 the distance between cities are great enough to enable the river to recover from these effects '5 before the next municipality is reached in each 5'4 case. -j+3
dissolved oxygen, and 1-, 5-, and 10-day biochemical oxygen demand. The turbidity, alkalinity, total hardness, and pH determinations have little sanitary significance in connection with this problem, but they are easily made and have some value in interpreting biological data. Bacteriological samples collected a t the same time were examined for total plate count on agar incubated for 48 hours a t 37" C. and for the determination of the number of organisms of the coli-aerogenes group. Another sample was collected in each cilse for plankton examination. The samples were collected by means of a sampler designed especially for the work, which made it possible to collect the samples for all the various analyses simultaneously and thereby insure comparative results. This sampler was similar to the one used by the United States Public Health Service in its studies on the Illinois River, and consisted of a pail containing a rack for
,,
Sampling
9.2 d'l
During the investigation of 1928 samples of water were collected a t intervals of 2 weeks from twenty-four stations on the Mississippi River and its tributaries below Minneapolis (Chart 1). Eight of these stations were located in the metropolitan area. The routine samples were subjected to the following physical, and temperature, turbidity, alkalinity, total hardness, pH,
L0
&
-'
Chart 2-Average for February and March, 1928 (See Chart 3 for June and July.) Oxygen Resources of Mississippi River Water Obtained by Balancing Diseolved Oxygen and Five-Da; Demand
February, 1930
INDUSTRIAL A N D ENGIXEERING CHEiMISTRY
holding several bottles, which were filled through separate glass tubes fitted into thimbles in the cover of the pail by means of one-hole rubber stoppers. The temperature, pH, and dissolved oxygen determinations were made in the field a t the time of collection and the remaining samples were shipped by express to the laboratory in Minneapolis. I n practically all cases the laboratory work was begun within 24 hours after the samples were collected.
Chart 3-Average for June and July, 1928
In addition to the routine sampling a biological survey was made of the bottom fauna at each of the regular sampling stations in order to corroborate the analytical findings. Collection of bottle samples was done by means of a Petersen dredge, which collected the material from a definite area of bottom and thus permitted an accurate comparison of biological conditions a t the various stations. The material was sifted in the field and the organisms were preserved and taken to the laboratory for identification and classification.
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problem, winter and summer, these two are taken as examples of the changes which take place in the oxygen balance. I n winter the water is cold and the biological activity is reduced to a minimum. Furthermore, cold water absorbs oxygen very readily from the atmosphere, and it would be expected that under these conditions the oxygen balance would be high. However, an ice covering over the river for 3 months or more prevents re-aeration from the atmosphere and as a result the balance becomes very low. A chart of the oxygen balance of the river in winter shows an increase in resources in passing over St. Anthony Falls (Chart 2). The balance then drops as the water passes through the pool above the Twin City Lock and Dam, becoming zero a short distance below the dam and continuing to be negative until the junction with the St. Croix River below Hastings. The lowest point on the curve is just below St. Paul. Below the St. Croix River the oxygen balance continues to rise until the water enters Lake Pepin. Because of the large amount of organic matter which has settled in Lake Pepin, the dissolved oxygen is considerably reduced by the time the water leaves the lake. However, the oxygen demand is practically satisfied at this point and from here on the pollution is local below each municipality. The Chippewa River entering just below Lake Pepin supplies a large amount of oxygen in the winter. During the summer when the water is warm the biological activity in the water and sludge is at its highest point and oxygen is not absorbed so readily as it is in colder weather
Information Collected During the course of this investigation information was collected relative to the quantity and strength of all sewage and industrial wastes discharged into the Mississippi River and its tributaries in Minnesota and Wisconsin. In the case of municipalities on the river proper from Minneapolis to La Crosse, inclusive, careful measurements were made and composite samples collected of the sewage and wastes from all important sewer outlets. From the information thus obtained the population equivalents of all the sewage and industrial wastes discharged into the river were calculated. The factor used in these calculations was a 5-day demand of 0.163 pound of oxygen per capita. These population equivalents are: metropolitan area, including Minneapolis, St. Paul, South St. Paul, and Kewport, 1,395,000; municipalities and institutions from Hastings to La Crosse, inclusive, 75,730. These figures are almost double the actual population of the sewered areas represented. Oxygen-Balance Data In determining the effect of pollution upon the section of the river under consideration, use has been made of the socalled oxygen balance. This balance is obtained by subtracting the 5-day biochemical oxygen demand from the dissolved oxygen. Although the figure thus obtained is a hypothetical one, it nevertheless represents the oxygen resources of the stream and gives a picture of what would occur if the water had no opportunity of becoming re-aerated. Since there are two critical oeriods in the studv of this .
Chart 4-Total Number of Bacteria per Cubic Centimeter a t 37.S0 C 48 Hours and Number of Organisms of Coli-Aerogenes Group &r Cubic d e n t i m e t e r , Averaged for Periods of 2 Months i n 1928
(Chart 3). -4s a result, conditions of pollution become acute and especially so in the pool above the Twin City Lock and Dam. - A s in the winter season, the situation ii improved
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Chart 5-Correlation
Vol. B, No. 2
between Various Criteria of Pollution a n d Recovery, February to July, 1928
after the Mississippi is joined by the St. Croix, but when the water passes through Lake Pepin the oxygen balance, instead of being reduced as in winter, is greatly increased as a result of photosynthesis and wind and wave action on the broad surface of the lake. I n seasons of high water the dissolved oxygen in the river water is always high and the ratio of water to sewage is so great that pollution does not present a problem except that a large amount of silt and suspended materia! may be carried down and deposited in Lake Pepin. As has been previously stated, the effects of these deposits are felt at other seasons, when they reduce the oxygen content of the water causing nuisances and bringing about serious losses of fish. Conclusions
The bacteriological data are very useful in determining the public health hazard to which persons using the stream for recreational purposes, such as boating, bathing, etc., are exposed, and especially in determining the load on a waterpurification plant which may obtain its water supply from the stream. The bacteriological and biological findings, as well as the chemical and biochemical results, show that the pollution from the Twin City Area extends into Lake Pepin but is reduced to a point which is comparable with conditions above Minneapolis before the outlet of that lake is reached (Charts 4 and 5).
Information obtained indicates that the river may be divided into the following zones: Zone 1. A zone of heavy pollution extending from Minneapolis to the junction with the St. Croix River. Water in this zone is unfit for use as a source of water supply and is a potential danger from a health standpoint to persons and livestock coming in contact with it. Nuisances are frequent and fish life has been practically exterminated in this zone. Zone 2. A zone of partial recovery extending from the junction with the St. Croix River to the head of Lake Pepin. Conditions are somewhat improved over Zone 1 as a result of the dilution effected by the addition of water from the St. Croix and the natural processes of stream purification. The river is unfit for use as a source of water supply, but nuisances are less frequent and fish life is less restricted than in Zone 1. Zone 3. A zone of more complete recovery through Lake Pepin. By the time the outlet of the lake is reached the water meets the bacterial standards for permissible loading of waterpurification plants. Zone 4. A zone of intermittent pollution and recovery below Lake Pepin. The water below Lake Pepin appears t o have practically recovered from the pollution introduced above the lake and the pollution in this zone is local below each municipality.
Following this investigation a detailed report was submitted to the Minnesota Legislature together with recommendations for improving conditions. It is probable that the studies will be continued for several years at least, in order to keep in touch with the situation and to determine when further recommendations shall be made.
Rubber Trees Grown Successfully in Florida Rubber trees are making good growth in Florida, but the experiments toward a domestic rubber supply do not yet justify conclusions, according to the Department of Agriculture. The Brazilian rubber tree has made rapid growth in Florida in the last two seasons. Many of the young trees in the department's experimental work have reached a height of 15 feet or more. They are of the same species of Hevea that is planted extensively in the East Indies and in other tropical countries. These trees are being grown at Chapman Field, near Miami, in the extreme southern
part of Florida, Many other rubber plants from all the principal rubber-growing countries of the world are being tried there in a limited way. A number of these plants are now being grown in southern Florida as ornamentals. No frost injuries occurred in the winter of 1928-29, and some of the Hevea trees with slat-house protection continued to grow, even during periods of cold weather. This indicates that the Hevea is much more resistant to cold than has been supposed and that the development of strains sufficiently hardy to grow readily in southern Florida is possible.
