Water Purification

Survival, Water, Medical Field Manuals

Military Manuals

Tweeddale, W.

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48 KANSAS ACADEMY OF SCIENCE. 

Fifteen individual grains were analyzed, and their variation was from 1.72 per 
cent, to 2.30. These figures show that, to make selection most effective, we must 
be able to separate the desirable kernels from the less so, and not depend simply 
on selection of ears. Upon this problem we are still at work. It is evident that 
we cannot analyze our kernel, and plant it too, and that some physical test only 
is available. Our task is to find a usable physical property which varies with 
the per cent, of nitrogen. The specific gravity suggests itself as best adapted to 
our needs. Investigation of this point has not yet reached definite results. The 
differences in specific gravity are very slight, and since parallel determinations 
of the nitrogen in single kernels are impracticable, a large number of analyses 
will be necessary before a positive result can be expected. The determination of 
the specific gravity, while theoretically simple by means of a heavy solution and 
the Westphal balance, presents considerable difficulty because of the adherence 
of air to the grain with great tenacity, and because of the occurrence of cavities 
within the kernels sometimes. 

Analysis of the several parts of the grain has shown that the germ is much 
the richest in nitrogen. Constituting about ten per cent, of the weight, it con- 
tains sixteen per cent, of the nitrogen. It also contains sixty-five per cent, of the 
oil. An increase in the size of the germ, therefore, will insure an increase in the 
percentage of the most valuable parts. Differences in the size of the germ are 
easily seen by simple sections through the kernels with a sharp pocket-knife, and 
ears can be selected showing a predominance of large germs. 



WATER PURIFICATION. 



BY W. TWEEDDALE, TOPEKA. 
Read before the Academy December 30, 1898. 

The character of the water-supply of a country is the determining element of 
its potential future, as regards its being the habitation of man, whether it be by 
the solitary pioneer or a community of individuals, as in ranch, village, town, or 
city like New York, with a population of millions. 

Modern sanitation requires that not only shall the quantity be abundant, but 
that the quality shall be suited to the uses to which it is to be applied. Medical 
science forbids that the cholera- infected water in the sacred tanks of India be 
longer used for dietetic purposes ; and in the same line demands that, if water 
for potable purposes cannot be procured, provision be made to render it so by 
some system of purification. The necessity for this purification is due to the 
very solvent power of water acting on solid substances, such as clay, the presence 
of which in a state of suspension causes turbidity, together with the solvent poWer 
of gases in water acting chemically on inorganic earth salts, causing the property 
termed hardness and the fermentation (putrefactive decomposition) of organic 
substances, the presence of which in this state constitutes the nidus for the de- 
velopment of bacteria. 

In this country the purification of public water-supplies has been mainly re- 
stricted to the removal of visible impurities in suspension, including bacteria. 
This is sought to be done by filtration or by subsidence. There are two systems 
of filtration: 1st, sand filters, English system, as it is termed, with or without 
being allowed to deposit the coarser particles by sedimentation ; and, 2d, the me- 
chanical filters, American system, combined with the use of a coagulant. 

Subsidence is the practice in cities whose sources of supply are the waters ob- 



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CHEMISTRY AND PHYSICS. 49 

tained from our western rivers, an example of which is St. Louis, Mo., which in 
this manner treats thirty-two million gallons per diem. In Europe, where water 
purification by the use of sand filters is general, the rate of descent of the water 
through the sand of the filter varies with the degree of turbidity, ordinarily, but 
about sixty gallons per square foot per twenty-four hours, or 2,500,000 gallons 
per acre per diem. 

The action of these filters is not alone that of strainers. The fermentation of 
the organic substances in the bed of the filter changes the organic constituents 
to inorganic nitrites and nitrates by the agency of bacteria. The mechanical fil- 
ters act only as strainers, as the rate of passage of the water through the filter, 
130 million gallons per acre per diem, is too rapid to allow of the reduction of the 
organic compounds by fermentation. 

In the process of purifying water containing organic matter by filtration, that 
portion in a state of suspension will be retained on the filter as a strainer, while 
that carried down by subsidence will be mingled with the other precipitated im- 
purities. In either case they will by decomposition be rendered insoluble, and in 
the case of the filter will pass off with the filtered water ; or in the case of by sub- 
sidence will be mingled with the purified water in the settling basin ; in each case 
containing the spores of any bacterial life there may be in the water, together 
with the soluble matters as a nidus for their development ; for which reasons the 
requirement is to use sand-filtered water soon after it has been purified. The 
value of filtration as a means for purifying water by the removal of bacteria can 
be judged from the following: 

Doctor Currier, biologist for the Syracuse Water Commission, experimented 
with a variety of filters, and found, even with the justly celebrated Chamberlain- 
Pasteur filter, under the hydrant pressure of New York city, when the flow was 
but drop by drop, that, when the filter had been sterilized by steaming for five 
hours, no bacteria passed through with the water ; but that after three days' con- 
tinued use the number of bacteria increased to 2500 per cc, and after five days 
of such use the number had increased to 400,000 per cc. These processes, which 
may be regarded as standard, take no account of the removal of inorganic sub- 
stances in solution in water. These substances are earth salts, rendered soluble 
by the solvent action of gases contained in the water, mainly carbonic and sul- 
phuric acid gases, so objectionable in water used- for washing or for use in steam 
boilers. Doctor Frankland, chemist to the Parliamentary Rivers Pollution Com- 
mission in England, regards the softening of water by the removal of lime, mag- 
nesia, etc., as so important that he recommended, in a report to the above-named 
commission, that all companies should be compelled to provide for softening 
water-supplies before being allowed to raise additional capital for the extension 
of water-works. It was estimated that the chalk contained in the water-supply 
of London was 160 tons per diem, and that the saving in soap, if that were re- 
moved, would be, approximately, £250,000, equal to $1,250,000; and a cost of one 
penny applied for purifying water would effect a saving of soap of three shillings 
and eight pence, or forty- four times as much. 

While the character of these impurities has been understood in a general way, 
it is only of late that any account has been taken of the effects, on nutrition and 
health, of hard water used dietetically. Based on mortuary statistics of a number 
of cities, it has been held that the hardness of water had no material effect on 
the death-rate; and, while it may be true that there is no direct evidence of this, 
there is much evidence that they exert a marked influence in inducing diseases, 

—4 



50 KANSAS ACADEMY OF SCIENCE. 

causing suffering if not immediate death. The effects produced by the dietetic 
use of hard water on the animal economy are : 

1st. Chemical. An illustration of the chemical effects of such use of hard 
water can be shown by putting a small quantity of the white of egg in each of 
two test-tubes, and adding to each the same quantity of bile from a freshly killed 
animal; then, after agitating for a short period of time, add to one of these tubes 
a portion of soft water and again agitate, when it will be found that the emulsion 
formed is perfect, rendering the contents assimilable and fitted for passing into 
the circulation. To the other tube add the same amount of hard water and agi- 
tate, when it will be found that the contents have coagulated into curd- like 
lumps, similar to soap in hard water, and be no more capable of providing nour- 
ishment than so much dissolved stone. 

The medical congress held in Brussels in 1886 passed the following resolution : 
"Waters that are too hard, or that contain mineral substances that do not as- 
similate with the food and constitute a part of the human system, form with 
chyle an abnormal medium for the formation of blood, and the presence of these 
substances in the blood throws additional work on the kidneys, whose duty it is 
to filter out and remove the wastes of the blood, the too great accumulation of 
which substances results in the formation of concretions." 

2d. Physiological. The distinguishing difference in the physical condition 
of the human system in youth and old age is in the increased amount of deposits 
of earthy matter. These are carbonates and phosphates of lime mixed with 
other calcareous substances. These deposits affect the physical organs and inter- 
fere with their action, causing imperfect circulation of the blood and clogging of 
the arteries. The change is in the nature of a slow, steady accumulation ; and 
when they have become excessive the stiffness of old age is produced. As these 
substances are constituents of the food we eat and of the liquid we drink, much 
can be done to prevent their injurious effects by a proper selection of food and by 
providing, for cooking and drinking, a water which does not contain these sub- 
stances, and also which by its solvent power will dilute not only the substances 
in the food, forming deposits, but also by acting on the deposits already formed 
fit them for removal, and thus tend to prolong the elasticity of youth. 

3d. Mechanical. The nature of the mechanical action of hard water used 
dietetically on the system will appear when we consider that in the process of com- 
bustion of the impurities in the blood the uric acid (ashes of the blood), collected 
in the kidneys as an ash-pit, must, as in the case of the ash-pit to the furnace, be 
removed in order to secure efficient action. For this end the requirement is that 
the fluids passing through the body be in a condition to dilute the uric acid and 
thus fit it for being carried off by the channels nature has provided for their re- 
moval. 

When waters used dietetically are charged with earth salts their solvent power 
is lessened, and they are in a condition to form deposits of the substances they 
hold in solution in the order of their solubility. Among the least soluble sub- 
stances in solution in this case, uric acid acts as a nucleus, forming concretions 
producing paralysis, dropsy, Bright's disease, etc. 

Dr. Lewin, of Munich, who made an extended and very careful study of the 
purification of water, gives the following as the requisites of any system of 
filtration : 

"It must absorb not only substances in suspension but also all matters phys- 
ically and chemically latent, and must so retain them that additional impure 
water or clear water cannot wash the impurities out ; or purifications must be 
carried on in such a manner as not to injuriously affect the purity of the water. 



CHEMISTRY AND PHYSICS. 51 

The arrangements also should be such as to retain the property of purifying water 
for a considerable length of time without deterioration." 

It is needless to state that this ideal purification of water has not been even 
approached by any known system of filtration in use. Such being the case, 
it is allowable to assert that no such system of filtration is possible; from which 
it follows that the solution of the problem of water purification to the above 
standard must be sought for outside of present methods, and that any process 
for the removal of injurious impurities in solution in water physically and chemi- 
cally latent will be incomplete unless means are provided for rendering all such 
substances fit for removal by filtration or by sedimentation by making them in- 
soluble and causing them to coagulate and unite with other impurities in 
suspension. 

With the above high ideal of water purification as a standard, the writer has 
invented an apparatus and a process which in combination provide for the fulfill- 
ment of the above conditions. 

The apparatus consists essentially of one or more vessels, tanks or reservoirs 
of any desired form or required capacity, with one or more oxidizers to each 
tank. These oxidizers are composed of metallic iron and coke arranged to form 
a galvanic battery, the size and number of oxidizers to depend on the dimensions 
of the tank, together with the requisite systems of piping for filling the tanks with 
water, agitating with air, drawing off the purified water, and removing the sludge 
whenever by its too great accumulation it is found necessary. 

process. 
The process fulfills the requirements above enunciated by Dr. Lewin of remov- 
ing all objectionable impurities in water whether in suspension or in solution, and 
that, too, without deterioration of the apparatus; and consists 

1st. By the use of chemical reagents, changing all substances in solution in water 
to an insoluble state in suspension. 

2d. By combination of the galvanic action of the oxidizer, the salts of iron, 
and aeration; these substances, now all in suspension, by coagulation and aggre- 
gation, are fitted for being precipitated by sedimentation. 

REAGENTS. 

The reagents for rendering the earth salts, held in solution by the solvent acid 
gases in the water, insoluble in suspension are alkalis for which the solvent acid 
gases have a greater chemical affinity than they have for the earth salts held in 
solution by them. The withdrawal of these acids renders these earth salts in- 
soluble. 

The reagents for changing organic substances in water, rendered soluble by 
putrefactive fermentation, insoluble are metallic iron, coke, and salts of iron. 

3d. The treatment consists in introducing into the tank the requisite amount 
of alkali necessary to absorb the carbonic acid holding the earth salts in solution, 
then fill with water; during the time of doing so and for the necessary length of 
time after, by means of compressed air, force the water through the oxidizer. 
This, in addition to thoroughly mixing the reagents with the water by bringing 
each particle of water into intimate contact with the material of the oxidizer, 
oxidizes or burns up the organic matter in solution in the water, thus render- 
ing it insoluble: in addition to which the galvanic action of the oxidizer in the 
water kills the bacteria and causes the impurities in the water to coagulate. 
After completion of reaction, test for excess or deficiency of reagents and correct 
to neutrality if necessary. Then add reagents to absorb the sulphuric acid, and 
again agitate, test, and correct. After completion of reactions to neutrality, add 



52 KANSAS ACADEMY OF SCIENCE. 

salts of iron. The effect of this is not only to complete the oxidation of organic 
matter in solution, but also to hasten coagulation and destroy any excess of alka- 
linity there may be in the treated water ; after which give final agitation and 
allow the water to become quiescent, when all the impurities in the water, now 
all in a state of suspension, will be precipitated by sedimentation. 

When settled, the water is taken off from near the surface by a floating pipe, 
clear, soft, free from bacteria, and sterile to the development of micro-organisms. 

The rate of precipitation depends on the condition of the water and the tem- 
perature. That of the water-supply of the city of Topeka at a temperature of 
sixty degrees is four feet per hour. 

This process, by making a filter of the now all insoluble impurities and by 
sedimentation, passing them down through the water, instead of by filtration 
passing the water through the filter, and by the accumulation of impurities in the 
body of the filter, resulting in the deterioration of the apparatus, provides for 
the complete realization of Doctor Le win's ideal water purification, and effects 
the following results : 

1st. The removal from the water of the earth salts renders the water soft. 

2d. The removal of the organic matter sterilizes it to the development of 
micro-organisms and the support of bacterial life. 

3d. Aerating the water renders it more palatable, when used for drinking, 
and allows of the more rapid formation of steam in boilers required for industrial 
uses. 

The cost of installation per square foot of surface will not exceed that for sand 
filters, while the rate of passage of water will be as twelve to one. The cost of 
operation will practically be that of the cost of reagent.