NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
Scientific Memoirs by
appropriate chemical conditions for their specific actions, until at last we obtain in
the effluent, a mob of organisms by which the final stage of purification is effected.
Oxygen alone is now required, and this is often present in the effluent to the
amount of 40 per cent. of the maximum possible, and more is provided by the salts
in solution for ultimate mineralization. Lastly, we may say, that although all sub
-
stances are not capable of fermentation—a process which may be described, in
its chemical aspect, as due to the erratic conduct of the "fixed" oxygen
atom, and failure will occur when the molecular constitution of the substance
is too large in relation to the number of displaceable oxygen atoms—yet we
meet with no difficulty of this kind in the case of the organic matter in
domestic sewage; nothing is left after the processes described but a negligible
quantity of "humus," which indeed does slowly disintegrate in time. Never
-
theless in sewage the organic molecule is large enough to demand the preliminary
hydrolytic fermentation before it can be effectively attacked by free oxygen.
Let us explain what has been said by the parable of the "spontaneous
combustion" of the haystack, which affords a striking example of the activity
to which oxidation of organic foodstuffs may attain, when decomposition of the
latter has previously set in. If hay is stacked before it is thoroughly dry, decom
-
position ensues in the middle of the damp stack, due to the action of bacteria
and their enzymes. Heat is liberated by the decomposition, and proportionately
with the rise of temperature in the middle of the stack, there is an ever-increasing
accumulation of easily oxidizable decomposition products. If the hay be now
disturbed so that there is free access of atmospheric oxygen to the interior of
the stack, the whole blazes up and is consumed. This, as will be seen, is exactly
parallel to the conditions we arrange in a "biological" apparatus with, first, its
anaërobic, and later its free oxidizing stages. This is a striking illustration from
Nature's economy that we can only apply our available oxygen, to the best effect,
when, and only after, we have prepared our complex waste materials for the
attack.
134
Pasteur on Putre
-faction.
Before summing up this part of our subject, a brief allusion to Pasteur's
original statement of the process of putrefaction in the presence and in the
absence of oxygen, may be made for its great practical and historical interest.
He pointed out, many years before anything was heard of "biological" methods
of sewage disposal, that in a body of fluid containing putrescible matters, when
air is excluded, the oxygen contained in the fluid is, firstly, completely used up
by certain aerobic organisms, and this accomplished, these organisms die and
fall to the bottom of the vessel. Now the true putrefactive bacteria appear upon
the seene and they perform their special functions only under anaërobic con-
Medical Officers of the Army of India.
135
ditions; they set up the putrefactive fermentation proper, but they require the pre--
paratory action of the aërobes. If, however, the fluid is exposed to the air, the
aërobes develop continuously at the surface and form a scum which at times
falls to the bottom in masses, but is constantly regenerated. The scum prevents
the access of oxygen to the liquid, and thus provides the necessary anaërobic
conditions for the putrefactive organisms below. The complex fermentative pro-
ducts, thus formed, serve as nutriment to the aërobes at the surface and the
latter break them up into the simplest compounds, water, carbon dioxide and
ammonia. [Sims Woodhead has since confirmed this, by the demonstration of
anaërobes in the lower part and body of an open tank, and of liquefying aerobes
on the surface, to the rôle of which in the second stage we have referred.] In
these words we have a prophetic statement of the advantages to be obtained
from the treatment of sewage in an open " Septic tank," or in an open upward
" cultivation tank" (Scott-Moncrieff) to which we shall subsequently refer.
But it is obvious that, in practice, in dealing with large bodies of sewage, we
cannot rely on this process alone for the sufficiently rapid mineralization of the
waste products; we should not only need apparatus of a size impossible to obtain,
but we should incur all the disadvantages and dangers of the old cess-pool
system, with loss of the immense manurial value of the organic matter.
Nevertheless it is clear that in fermentation without oxygen we have so far gained
enormous advantages in the breaking down and solution of the solid waste, which
is now rendered far more readily susceptible of final oxidation.
Coming now to the practical application of the principles which govern
the biochemical forces in action, we see that we must provide the following
stages for their distinct rôles:—
(1) For anaërobic liquefaction and solution of the solids—albuminous,
carbohydrate and fatty. This is best accomplished in what is
called a "septic tank," closed or open, or by upward filtration
on the Scott-Moncrieff plan, which resembles in all essentials the
open septic tank, but possesses certain important advantages in
that it provides a far better nidus for the organisms and an enor
- m o u s l y i n c r e a s e d a r e a f o r t h e i r c u l t i v a t i o n u n d e r s u i t a b l e c o n d i t i o n s ;
it also allows of the initiation of the second stage of partial oxida
- t i o n , a n d b y s o m u c h s a v e s t i m e , a n d t h e s t r e s s o n t h e a p p a r a t u s
provided for the second stage. (See Part III.)
(2) The second stage in which the intermediate products are broken
down by fermentation in the presence of a certain amount of
oxygen, and here intermittent downward "filtration" is indicated.
The practical
application.
136
Scientific Memoirs by
The effluent flows from the top of the first upward tank on to the
surface of the downward filter, which is allowed to fill, and without
resting, is then discharged and carried by pipe or conduit, to—
(3) Porous arable land at some distance, where the third stage of complete-
aëration and nitrification, transforms the ammonia, nitrites and
carbonaceous residues to the final terms of carbon dioxide, water
and nitrates. The whole mechanical part of the process may
be made practically automatic, as will be shown when we discuss sug-
gestions for reform of our present methods, where also we shall deal
with the supply of water required and the method of removal.
The above broad indications are set forth with a due sense of responsibility,
but with the confidence born of practical experience of the working of the different
types of installation now on trial in England, viz., the Septic tank, the Scott-
Moncrieff plan and the systems of downward filtration, intermittent and continuous
(the Dibdin, the Ducat, the "Absaf " processes). These last are entirely unsuited
to the concentrated sewage of cantonments, and of natives, even with the most
extravagant preliminary dilution with water. If the outward forms of the apparatus
be legion, there are, in truth, but two types; the one which makes a preliminary
hydrolytic process essential previous to oxidation, and the other, which relies on
fermentation in the presence of air throughout, and where the different stages
we have followed are perforce confused. The marked differences in the character
and strength of the sewage in India and in England respectively, sufficiently
indicate that the latter processes, which may deal creditably with the excreta
diluted with 30 to 40 gallons per head, after a long passage through sewers,
(where the hydrolytic transformations are largely carried on) are entirely out of
place in India, where the dilution is much smaller and where the unabsorbed
proteid from vegetable food amounts in the excrement to as much as 10 to 20
per cent. of the total ingested, and where also from 30 to 50 per cent. of the
Cellulose leaves the body in its integrity, and can only be decomposed under
anaërobic conditions.
Necessity for pre-
- l i m i n a r y a n a ë r o b i c
stage.
And, it may be added that an enormous economy of space and apparatus
accrues from the division of labour obtained by a preliminary anaërobic hydrolysis,
where concentrated sewage has to be dealt with, and as Scott-Moncrieff has said,
the stronger the sewage the more vigorous and complete is the fermentation set
up in the anaërobic stage. Finally, it is absolutely certain that it is radically
unscientific to depend solely on downward filtration, where all classes of organisms
are confused in antagonistic action; and in practice, as the writer has proved,
Medical Officers of the Army of India.
137
these filters rapidly choke and become useless, because the larger proportion of
solids is not in solution.*
Comparison of
biological methods
ith earth disposal.
We shall not detain the reader with a statement of the advantages and dis-
advantages which accrue from the employment of the " biological " method so-
called, as compared with the present system of direct earth-disposal. The first
part of this paper provides a sufficient indictment of the latter, and in considering
its merits and demerits one must give full weight to the most important question
of " removal," and of the removal and disposal of the considerable quantities
of waste water of various kinds that by the present arrangements are a standing
menace to the community. Briefly, it may be said that labour is multiplied,
and that supervision is inadequate, however conscientious, and we have no right
to expect the best results from this hide-and-seek policy, which opens the way to
dangerous risks at every stage. Its chief justification lies in the return of plant
food to the soil, but if cultivation is neglected or impossible, its rationa.e is lost,
and if cultivation be carried out, it is secured at the risk of infringing other
cardinal principles of disposal, viz. , that it should be sure, rapid, complete, innoc-
uous and economical. Do we, in fact, fulfil the conditions formulated in the
words of Sir J. Simon that we have quoted, and will anyone deny that they are
indispensable, or aver that they are impossible ?
There is full warrant in the evidence adduced 'that the " system " is no
system, and that it has demonstrably failed in the essential points we look to
it to fulfil. Even in its best form, as regards disposal only, viz. , in the Allahabad
system of surface trenches, there are special dangers in the varying extremes of
the Indian climate ; it is employed in only a few places, and is not everywhere
possible of application. Cultivation is delayed, or is not possible at a time
when the danger is greatest, and there is the difficulty about the necessary
water for irrigation of the crops.
" The careful and intelligent cultivation of the land is the point on which
the system breaks down in practice."— Quarter Master General in India. †
* The extraordinary nature of a typical Indian sewage may be appreciated by a glance at the following
figures, the average results of many analyses, the dilution per capita being 5 gallons :—
Pts. per 100,000.
Total dry solid residue ...
...
...
...
...
. . . 432
Solids in suspension
...
...
. . .
. . .
. . .
. . . 244
Solids in solution
...
...
...
...
...
... 188
Ammonia (Free)
...
... . . .
. . .
. . .
1 4 . 5
Ammonia (Albuminoid) ...
...
...
...
...
...
9 . 3
Note the excess of suspended over dissolved solids and the very large amount of Albuminoid
Ammonia, due probably to the undigested grain and vegetable food; compare this with English sewage.
(Simla experiments).
† See letter of Quarter Master General to L. G. Cs. of 29th June 1900.
LL
138
Scientific Memoirs by
Objections to bio
-logical methods.
Answers to objec
-tions.
The objections that have been raised in this country against the more
artificial biological methods, and which at present appear to stand in the way of
their adoption are—
"Want of more extended experience of the system; the necessity for
an abundant and cheap supply of water for purposes of dilution."*
The doubt as to the passage through the apparatus of pathogenic germs.
Possibly, a potent factor in a policy of
fainéance is the prime cost.
As regards the first, it may be said that experiments already made in India
have put the matter beyond doubt, as far as the main issue is concerned, even if
details vary and require elaboration in minor points (see reports from Bombay,
Poona, Calcutta and Simla); and further there appears to be no reason why the
Government which has hitherto stood aloof from the enquiry, should not redeem
the time by instituting experiments in different places under competent advice.
Is the question to be worked out by private corporations and individuals, whose
results will doubtless be held to require confirmation?
As to the second objection, experiments in India have fully demonstrated the
capacity of the biological methods to deal with the excrement of natives which
averages 10 oz. for each person, with all its undigested food residue and
large excess of cellulose, with a dilution of 5† gallons per head, and it is certain
that the European adult average of 5 oz. could be submitted to the pro--
cess with equally good results when diluted with 3 gallons of water, not only
because of its relative diminution in bulk and weight, but because of the compara--
tive absence of undigested residues.
Does the European soldier receive, for ablutionary and culinary purposes,
less than 3 gallons of water per diem? If he does, the difficulty of supple--
menting the supply to reach this amount is surely not insuperable; but is it too
much to ask that this amount of fresh water should be set aside for the purpose of
diluting the excreta? One of the objections raised against trenching grounds
is the lack of irrigation water for cultivation; the intermittent bestowal of a
"purified" effluent from a "biological" installation not only returns the necessary
nitrogen to the soil for manurial purposes for raising crops of vegetables, but it
brings at the same time the required supply of moisture, while it relieves the
inhabited site of so much stagnant waste.
Do pathogenic or-
ganisms survive bio-
logical methods?
As for the third objection, there is certainly no intention on the writer's part
to minimise its importance, but first, it must be noted that it is hypothetic and
inferential. If pathogenic germs be contained in the solid and liquid excreta
— a n d i t m a y b e t a k e n a s c e r t a i n t h a t t h e y d o — w h a t a r e w e t o s a y o f t h e p r e s e n t
* See letter of Quarter Master General to L. G. Cs. of 29th June 1900.
† Three gallons in the Calcutta experiments.
of obtaining adequate supervision, absolutely essential for carrying out trenching,
is largely minimised, and with a proper integral system of removal is almost entir
e -
ly obviated, while the risks to health, to some extent incumbent on all methods,
are reduced to a minimum. In larger communities installations can be
e s t a b -
lished at suitable points, and so save the cost of large schemes for the devolution,
of all the sewage to a common outfall; smaller communities need not wait for the
large comprehensive schemes required by towns in or near which they are situated.
As regards the final disposal of the effluent, we have doubtless something yet
to learn, if it be desired to discharge it into a stream. Our own opinion has been.
stated, that no means of disposal can compare with land irrigation both for safety,
and for the return we desire in the shape of vegetables and other crops which,
will go far to recoup the expenses of the first cost of the necessary apparatus.
Still, where a foul nullah or water-course is the only resource, we may rest
assured that, so far as the chemical effect of the effluent is concerned, a great
purification of the stream is secured, from the biological and chemical forces,
which characterize the effluent (see Manchester experiments, independently
confirmed by those made by the writer at Simla, in 1899-1900).
We come now to a brief discussion of the practical application of the prin
-
ciples which have been set forth in the preceding pages, and we must premise
that our object is "the perfect adaptation of drainage, water-supply and scavenage
to the purpose of carrying away, inoffensively, all refuse materials of life from the
person, the house and the environment, so soon as possible after their formation,
and with as near an approach as possible to one continuous current of removal,"*
and with this, their speedy, safe, complete and economical disposal.
It is clearly impossible to indicate here in exact detail the precise measures ne-
cessary to achieve these objects, which must be grasped in their organic unity ; the
special conditions of each community and locality must necessarily be studied and
the measures must be adapted thereto. What follows must therefore take the
form of general suggestion, which will not be found difficult of application, pro-
vided that the necessity for a radical reform of our present methods, and the prin-
ciples which should guide us to that end are accepted as an undeniable obligation
by those responsible for the lives and well-being of our troops.
The subject on its practical side will be dealt with, briefly, under the follow-
ing heads: (I) removal of excreta and, polluted waste water; (2) disposal; (3)
water-supplies; (4) general remarks.
* Sir J. Simon (loc. cit.)
142
Medical Officers of the Army of India.
145
or at proper intervals along its course. If, on the contrary, no extra supply
of fresh water could be allotted to the latrine W, Cs., the lavatory waste is at
disposal for this purpose, 300—350 gallons of it being pumped or carried up into
the latrine tank which should be provided with a scum and grease trap, and the
rest being admitted to the connecting drain by siphon flush. However, if,
as is understood, the amount of water per head is to be raised, as a rule, t
o
15 gallons for European troops, there seems to be no valid reason why, in most
cases, 3 gallons of this should not be available, in the fresh state, for the
W. C. flush. A separate fresh supply should be aimed at, and it is
thought that if the matter of the quantities of water actually supplied and
actually used in each barrack be enquired into, it will be found that in most
cases, this can be effected with the pumping, and even with the pakhali, power at
disposal. A strict enquiry into the amount of water available, into the amount
supplied, and into the amount used is necessary before deciding this question.
It may merely be a matter of inadequate water at command, while the pumping
or other power is quite adequate; in which case it will often be possible by
deepening old wells or sinking new ones to get over the difficulty. If the supply
is adequate, the transport power may be augmented.
The different latrine drains (four inch) should, it is suggested, be conducted
in comparatively short lengths, according to the exigencies of the site and their
mutual position thereon, to a five or six inch sewer-pipe, which may either be
placed in front or behind the latrines (according to the position of the barracks
and the advantages of the natural fall afforded); this five or six inch sewer should
either slope from one end to the other of the line of buildings, or from each
end to some intermediate point, from which another six-inch sewer will
conduct the collective drainage of all the latrines to the installation; a
manhole will be necessary at the junction of these two sewers, unless they
run in one continuous line to the installation. Manholes are required at
any considerable bends or variations in gradient, but in the small area to be
drained these should rarely be required. Where two or more regimental lines are
contiguous, these larger five-inch connecting sewers may be utilized to subserve
the off-flow from the latrines of more than one regiment; a six-inch connecting
sewer would possibly serve for three regiments. The lavatory waste water
provides the motive power of the system, and this can best be utilized by being
conducted to automatic flushing tanks, at the higher ends of the combining
sewer, one at each upper end of the sewer, if this is to slope to an intermediate
point for junction with the final collecting sewer; or the flushing tanks may be
placed at convenient intervals along the combining sewer, and they should be of
NN
Scientific Memoirs by
100 to 300 gallons capacity according to the length of sewer to be flushed.
All these are points upon which precise action can only be taken after a careful
survey of the site, and are given here in the form of a general idea, which may
easily be modified according to the particular facilities or difficulties met with.
It is believed that, generally speaking, a fall all over, of 1 in 100—say 15 feet in a
course of 500 yards, will be ample, to give the required gradient for self-cleansing
with the flushing arrangements provided But this will vary of course according
to the size of the drains and sewers, and the quantity of sewage to be discharged
in the unit of time, questions which Engineers will have no difficulty in deciding.
It should be added that the cook-house waste water should be diverted to the
drainage channels at the nearest convenient point.
But if the necessary fall be not obtainable, we may easily increase it to a con
-siderable extent-by depressing the installation, or rather the first part of it—the
hydrolytic tank or bed—by excavating, and building it well below ground level. For
instance, taking the first upward filtration bed, we could lay its foundations some
10 or 12 feet below ground level (or even more), so that the end of the discharg
-ing sewer and the effluent pipe (which are approximately on the same level)
would be six feet or more below ground level, giving us this amount of fall in addi-
tion to the natural gradient. The effluent pipe would discharge into a pucka well
built on to the end of the tank and by the aid of a "Persian wheel" worked by
one bullock, the first effluent could be raised some fifteen feet or, say, 7 feet above
ground level; it would be discharged on to the aërating filters above ground
level, and as these are only three feet in depth, there would be the advantage
of four feet in addition to the natural fall for the gravity necessary to carry the
purified effluent to the land to be irrigated. The same device may be applied by
the alternative method of pumping, but the Persian wheel, which is easily
worked and repaired by a native, would probably be as effectual in most cases
and less costly; a pump however would allow of a still steeper fall from the bar
-racks to the installation, and raise the effluent higher, and so give a better final
gradient. (See Plate I.)
There can be no question, then, that this system of immediate and direct
removal is perfectly feasible in cantonments standing on the flattest sites; but
it is confidently believed that these supplementary devices will not often be neces-
- s a r y , s i m p l e a s t h e y a r e W e h a v e g o n e i n t o t h i s s u b j e c t a t l e n g t h , b e c a u s e
of the conviction that complete and prompt removal is not a whit of less impor
-tance than adequate disposal. If we attempt to deal with the question by half
- h e a r t e d a n d p a r t i a l m e h o d s , w e s h a l l n e v e r a t t a i n t h e e n d i n v i e w . T h e o n l y
alternative is the cart-carriage nuisance, which retains one of the chief dangers of
the present system, and even this must not, at any cost, be worked as at present.
146