THE RECLAMATION OF MILITARY ORGANIC WASTE
In deciding the type of plant suited to the recovery of military
organic waste regard was specially devoted to two governing principles.
The one was the standardization of plant, so far as was practicable, to
facilitate duplication and installation of the machinery in the various
camps. The second was the selection of such plant as could be installed
readily and cheaply in an improvised building, and which, if the
conditions warranted, would enable a standard type of cheap and simple
building to be adopted.
So far as the initial plants were concerned dependence had to be
placed upon existing structures, otherwise delay in putting the scheme
into practical application would have been inevitable, owing to the
difficulty attending the acquisition of constructional material. But
the installation of the plants in extemporized buildings sufficed to
establish the applicability of the idea to any type of building of
adequate dimensions, and in such a manner as to impose only the minimum
of structural alterations to secure the requisite efficiency. This
adaptability is an outstanding feature, because it indicates how the
recovery of organic waste may be attacked along the most economical yet
comprehensive lines, and with the minimum of capital expenditure and
its concomitant amortization charges.
Two types of plant were adopted, both being standardized. One coincided
with what might be described as the central or permanent waste-recovery
station, while the second presented all the necessary elements of
portability with the added advantages of inexpensive dismantling,
removal, and expeditious reassembling at another point according to
exigencies. But the processes are common to both types.
In the case of the permanent mill which I visited structural
alterations had been reduced to the absolute minimum, the most
conspicuous outlay being the provision of a simple form of elevator to
lift the swill to a level above the plant to permit of gravity feed.
The total cost of this station, including the installation of the
necessary machinery, which included a steam-boiler, bone-crusher, small
engine, melter, centrifugal or turbine fat extractor, and settling
tanks, with one or two further accessories, was only £2,500--$12,500.
The swill is brought to the mill by motor-lorry. Operations are
commenced at an early hour, because health considerations demand that
waste of this character shall be handled with all possible promptitude
in a big camp. The clearance is carried out daily and is complete,
including all garbage, bones and other profit-yielding organic residue
from the cook-house. Segregation is conducted as far as practicable at
the source, special sanitary vessels for distinctive residues being
provided. The mill continues working throughout the day until the whole
of the morning’s collection has been duly treated. No accumulation or
carrying-over of some of one day’s swill to the next day is permitted.
Swill is susceptible to speedy fermentation, especially during hot and
sultry weather, and so would become noisome within a very short period,
as well as developing into an ideal breeding-ground for flies and other
pests.
The contents of the collecting lorries are distinctly heterogeneous,
the vehicles being laden with swill, bones, empty tins, jam and pickle
jars, bottles--in short, anything possessing an element of salvage
value. In segregating the waste at the cook-house special stress is
laid upon the necessity to keep all green vegetable matter, such as
outer leaves, stumps and other inedible trimmings, distinct from the
general swill for the reason explained later.
The swill is transferred by the elevator to the upper level, where it
is dumped into a capacious sink to drain. The proportion of free liquid
is not pronounced, the swill being rather in the nature of a slush,
whatever fat there may be present, apart from the solid pieces, being
either congealed in flakes and globules, either free or clinging to
the more stable substance. The superfluous water having run off the
residue is permitted to fall through a trap into a hopper feeding the
capacious cooker or melter. Where the height of the building does not
permit the provision of an elevated draining sink the swill, dumped at
ground-level, is shovelled into the melter.
The melter is a cylindrical vessel or drum fitted with a steam jacket,
the steam circulating at a pressure of about 80 lb. per square inch
through the annular space between the inner and outer jackets. The
capacity of the vessel is approximately 1,700 pounds, and the contents
are kept agitated during the process by paddles mounted upon a
revolving shaft forming the longitudinal axis of the drum.
The cooking process drives off all remaining moisture in the form of
steam, and, at the same time, liberates whatever fat may be present
by melting and rendering it fluid. It gravitates to the bottom of the
cylinder to make its escape through a suitable vent and pipe into the
settling tank. The last-named is also steam-heated by a coiled pipe
system which not only sterilizes but clarifies the reclaimed fat, which
is then permitted to cool and to solidify.
The swill remains in the drum for 70 to 90 minutes. By the end of this
period the contents have been practically cooked, while all free fat
has effected its escape. It will be observed that the steam does not
come into contact with the contents, but is confined to circulation
between the jackets. When withdrawn from the melter the swill resembles
a stiff slush. This is transferred to a canvas bag to be dropped into
a wire cage forming the inner vessel of the second machine, which is
a vertical turbine extractor. The vessel when charged is closed by
clamping down the lid.
Steam is turned on and the second stage of the fat reclamation process
proceeds. Beneath the wire cage a series of steam jets are radially
disposed in such a manner as to allow the steam to impinge upon the
cage at an angle. The cage itself is supported freely upon a suitable
vertical shaft and so, under the impetus imparted by the steam issuing
from the jets, naturally revolves. By varying the volume and pressure
of the steam the revolving speed of the cage may be varied within wide
limits. Consequently it is possible to give the cage a very high rotary
velocity.
The steam, after performing its mission towards rotating the cage, is
induced to ascend in such a manner as to permeate the contents of the
canvas bag imprisoned within the wire cage. All fatty matter still
associated with the organic material, owing to the high temperature of
the steam, becomes still more fluid. Under the centrifugal action set
up by the high rotary speed of the cage this fat becomes separated from
the solids to be expressed through the pores of the canvas container
and also the perforations of the outer cage, and to be flung against
the inner wall of the extractor. The extreme fluidity of the very
hot grease facilitates and expedites this separation, the expelled
fat finally dropping to the bottom of the vessel to make its escape
through suitable drain holes to pass into the settling tanks previously
mentioned.
Under the whirling action of the turbine quite 91 per cent. of the
fatty content of the mash is extracted and recovered. The treatment
in the turbine extractor is continued until the flow of grease to the
settling tanks is observed to cease, when steam is shut off and the
extractor is emptied. The mash, somewhat resembling peat in consistency
and of a rich chocolate colour, cooked through and through, is spread
upon the floor to cool. Unless one has followed the cycle of operations
one would never associate this odourless, clean, dry and sterilized
product with the repulsive looking slush from the swill-tubs which had
entered the mill barely two hours previously.
This residue constitutes an ideal pig-food. It is rich in the
essentials for building up the frame and flesh of the porker, and as
may be supposed finds a ready sale. It appeals to the farmer because
it is clean to handle, is easier to transport than the conventional
swill, because it can be bagged, while it possesses excellent keeping
qualities. In effect it is a concentrated food, and accordingly can be
broken down by blending with ordinary swill to increase the calories
of the latter as they affect the pig, or it may be used instead of
pig-meal, for which it is an excellent substitute.
Finally, it meets with the farmer’s favour because its fat content,
being only about 9 per cent., coincides more closely with the animal’s
dietetic requirements. It is not surprising, in these circumstances,
that the farmer should be eager to procure as much of this sterilized
food as he can obtain at a fair price. Certainly the authorities
experience no difficulty in regard to its disposal at a remunerative
figure.
The bones, upon reaching the mill, are dumped apart. They represent
waste from the cook-house stripped as cleanly of meat and fat
as a sharp knife in dexterous practised hands will allow. Their
gravy-yielding and other nutritious constituents have been extracted
from prolonged sojourn in the stock-pots. When they reach the
swill-mill they appear to be as capable of rendering any further
contribution to the general scheme as those bones which have passed
through the hands of a frugal housewife. They have reached the stage
when such refuse is either thrown into the kitchen fire, dust-bin, or
handed over to the peripatetic rag-and-bone monger.
Yet they still possess distinct fat value, but it can only be wrung out
by drastic effort. The bones are first passed through a crusher to be
reduced to small size. At times the bone-dump from the cook-house will
be found to be swollen by the dismantled framework of what was once
a horse or some other animal, and which is to be passed through the
fat reclamation factory. The crushed bones are submitted to the same
process as the swill, being passed through the melter and extractor
successively. The combined action of cooking and whizzing brings about
a far more impressive release of fat than may possibly be imagined.
Furthermore, cooking and whirling effectively release all slender
strings and shreds of fat which may have escaped the butcher’s sharp
knife, while clinging tatters of meat and sinew are also thoroughly
cooked. Upon withdrawal from the extractor the bones are thrown over a
riddle, this action being sufficient to detach all shreds of fibrous
matter which fall through the meshes of the sieve.
The bones are now ready for dispatch to the degreasers. The loose
fibrous residue resulting from riddling is collected for subsequent use
in the preparation of poultry foods. Seeing that the treatment of the
bones in this mill is pursued for the express purpose of reclaiming
only the loose and easily secured fat and grease there is no conflict
with industry. The degreasers are concerned rather with the recovery of
fat resistant to ordinary salvage methods, as well as glue, size, and
many other commodities involving the submission of the bone waste to
many special processes, the ultimate residue being ground up to form a
fertilizer.
The fat, after cooking, clarification, and solidification, presents an
attractive, odourless, sterilized mass. This is dispatched to the trade
for resolution into tallow, glycerine, and the requisite basic material
for the production of soap.
I mentioned that, in the segregation of the wastes at the cook-house,
special emphasis is laid upon the necessity to prevent the combination
of all green vegetable refuse with the swill. This is essential,
because in the subsequent cooking operation the dye from the green
waste is extracted as every housewife knows, and, mingling with the
fat, will steep the latter a pronounced greenish hue. This detracts
very pronouncedly from the value of the fat because the dye, being
of vegetable origin, cannot possibly be eliminated in the subsequent
manufacturing operations through which the fat is passed. On the other
hand, the deep yellow tinge which is likely to result from the presence
of curry waste in the swill is not deleterious because it can be
readily discharged.
For some time the disposal of the green vegetable waste presented a
thorny problem. Farmers were not prepared to purchase it with the
ordinary cooked pig-food, for the simple reason that they already
possessed a surfeit of this refuse in their fields. Cremation appeared
to be the only possible solution of the difficulty, the accumulations
being somewhat formidable, but as a result of experiment the difficulty
was very neatly and profitably overcome. This garbage, together with
other waste of a comparative character, is subjected to a desiccating
process to yield a product which is adapted to association with other
approved by-products, without depreciating the pecuniary or other value
of the whole, for poultry feeding.
Both plant and processes are extremely simple. Nor is a pretentious
staff required. Six men suffice to attend to an installation capable of
dealing with the swill contributed daily by a unit of 15,000 men. One
hand tends the engine and boiler for the supply of steam and power; two
men are responsible for the conduct of the melter; while two additional
men wait upon the turbine extractor. The sixth man is retained to
operate the bone crusher. This staff need only be increased, as the
volume of work rises from any accretion to the camp, to the extent of
one man for every additional 5,000 soldiers.
The wastage of bread, for the most part inadvertently, is far heavier
than may be supposed. Possibly the heaviest proportion of waste arises
from unconscious crumbling of the article during conversation at the
table. Observation revealed that the accumulation of such crumbs and
crusts was pronounced, while it was also discovered that a heavy
contribution was extended by the bakery as the result of cutting up the
loaves. The loss of flour incurred during the preparation of the bread
and pastry was also found to be appreciable.
Thereupon it was decided to reclaim all bread waste and flour residues.
The crumbs, together with the odd crusts and other small fragments, are
collected, while the bakery floors and tables are regularly swept to
yield grist to the salvage harvest. Moreover, despite the observance
of all possible precautions to avoid waste, accidents are unavoidable.
Occasionally a batch of bread is ruined in the baking. Being unfit
for human consumption it is handed over to the salvage department to
be worked up into readily marketable products instead of suffering
destruction as was formerly the practice.
Bread and flour waste is subjected to a simple and inexpensive
roasting treatment and is then roughly graded. The larger fragments
and condemned loaves are reduced to a convenient size, while the
finer material is reduced to a meal. The granulated residue is
absorbed by the firms specializing in the manufacture of compounded
proprietary poultry foods, entering into the composition thereof to
approximately 20 per cent., which experience has proved to represent
an excellent balance. During the war this granulated waste, sold in
bulk, realized about 1¹⁄₈d. (2¹⁄₄ cents) per lb., plus an additional
charge of 10 per cent. to cover administration expenses. The coarser
grade of waste proved to be an excellent feed for horses--superior to
oats--and consequently was somewhat in demand at 1³⁄₄d. (3¹⁄₂ cents)
per lb., the availability of such feed during the period when horses
were necessarily rationed owing to the shortage of the conventional
feeding-stuffs being keenly appreciated. In this instance the extra
charge on account of administration expenses was also made.
Other expressions of military “save-the-waste” activity cover the
recovery of tins, bottles, and jars. But the difficulties concerning
transport somewhat adversely affected success in this direction
for a time. The preserve and pickle manufacturers intimated their
readiness to accept all bottles and jars owing to the short supply
of new receptacles of this character, but for some time it was found
impossible to spare the requisite carrying facilities. The provision of
canned and bottled comestibles does not enter into the official scheme
of rations, the supply of such articles, “extras,” being conducted
through the Navy and Army Canteen Board, which, as a protection,
imposes a charge upon all jars and bottles sold to the canteen attached
to a unit. As a result every care is observed to preserve these
vessels to avoid any financial loss arising from their non-return.
Consequently, consignments of empty jars and bottles are generally
returned intact, such losses as are incurred being unavoidable, and, in
the main are due to accidental breakage.
An effort was also made to discover a possible commercial outlet for
spent tea-leaves. This beverage is particularly popular in the army,
and the accumulation of this waste is enormous. At one period the
Home Commands were called upon to handle over 13,500,000 pounds of
this refuse a month. The thought was entertained that the extraction
of the caffeine from this residue might prove a profitable venture,
but the experiments were inconclusive, and so the proposal was
abandoned. Then the circumstance that the tea-leaves carry a certain
proportion of potash suggested another line of application--conversion
into fertilizer. But here again success failed to be recorded. The
profitable exploitation of spent tea-leaves still awaits conclusive
resolution. But it happens to be one of those problems beset with
supreme difficulties, while it is imperative that every precaution
should be observed to prevent this waste finding its way into
unscrupulous hands to be turned to base account to the disadvantage of
the community.
I have already mentioned that, while every effort was made to recover
the uttermost ounce of fat-yielding residue from the kitchens, every
encouragement was extended to the troops to cultivate the consumption
of the nourishing dripping. Although it would seem as if these two
recommendations were in utter conflict, no such trouble as might
have been anticipated has been recorded. The troops appreciated the
concession, and the request for this fat has led to considerable
fertility of thought and individual resource among the officers of the
various units. Such initiative received commendation from headquarters
because it not only contributed to the economical consumption of food
in the army, but reacted to the advantage of the civil population
who, unable to obtain dripping owing to the rigorous meat rationing
in operation, were compelled to depend upon butter and margarine
for their fat requirements. The increasing consumption of dripping
by the soldiers to whom it was readily available served to permit
increased quantities of the restricted supplies of other articles to be
distributed among the community.
In one cook-house I witnessed an interesting method to increase the
dripping yield. A big pail had been filled with little shreds of
fat and meat, shaved and scraped by the cooks from the bones of the
freshly-cut-up quarters of beef. This pail was placed within an outer
vessel containing water, the improvised double saucepan then being
placed upon the hot stove. As the water boiled the fat clinging to
the shreds of fibre dissolved, while the meat-juices also became
dissociated from the fibre under the influence of the heat. Boiling was
continued until the whole of the fat had melted, when the vessel was
removed and set upon one side to cool. The fat solidified at the top
to yield a fine chunk of appetizing rich dripping, while immediately
beneath was a jellied mass of gravy and disintegrated meat-fibre,
forming a concentrated beef-tea. The dripping was reserved for issuance
in lieu of butter and margarine, while the jelly sediment was set upon
one side to improve the contents of steak-pies, puddings, and other
savoury dishes.
The soldier is also a gourmet for cheese. But exigencies of war
speedily elevated this comestible to the status of a luxury, even
in the army. Unfortunately the average cheese does not lend itself
to economic use. It is friable, the loss in crumbs being somewhat
pronounced, while the rind is lost.
An officer conceived an ingenious idea to persuade the cheese to go
farther, and in such a manner as to eliminate all possibility of waste.
A whole cheese was taken, thoroughly washed and cleaned. It was then
placed in a mill with a quantity of dripping, the proportion being
60 per cent. of the former to 40 per cent. of the latter. The two
constituents were then pulped and blended together.
The resultant product was distinctly surprising. The cheddar cheese
was converted, by compounding with the animal fat, into a delicious
cream-like article of the consistency of butter, allowing it to be
spread upon bread and biscuits. The flavour was distinctly improved;
indeed, the soldiers expressed a decided preference for this blended
food. Its nutritive value cannot be gainsaid, because it carries all
the virtues of the cheese plus those incidental to rich animal fat.
By this simple expedient all wastage of cheese was overcome. Even the
rind, generally conceded to represent the richest part of the product,
was used, being thoroughly disintegrated, macerated and blended with
the dripping by passage through the little mill. Not only did the
officer reduce the item for the consumption of cheese by his unit to
a very significant degree, but he achieved the desired end without
penalizing the men to the slightest degree.
The process is so simple that it might even be emulated to profit by
the thrifty housewife. The kitchen mincing machine will suffice for the
purpose. It is only necessary to pulp and to blend the two constituents
thoroughly together. It certainly offers a means of inducing a pound
of cheese to go as far as, if not farther than, a pound and a half has
ever gone before.
In so far as the arrest of the elusive fat was concerned there remained
only one other possible avenue of escape demanding interruption. This
was the sink where all plates, dishes, and cooking utensils in general
are washed. In the first effort to secure this contribution the hot
water carrying the desired material was led into a pit. Here the fat
collected in the form of a scum, which was skimmed off at intervals and
sent to the swill mill for further treatment. But this crude method
gave way to one more in consonance with modern ideas. The fat is now
caught at the gully.
One device I saw installed to achieve this end was of an extremely
simple character. It comprised a wooden box, about three feet in length
by one foot in width, and about two feet in depth. It was subdivided
into three cells by two partitions, which, however, did not extend to
the full depth of the box. The pipe from the sink entered the box at
one end while the outlet to the drain was placed at the opposite end.
The box was filled with cold water, which need only be renewed when the
box is emptied for cleaning and flushing, since normally it is kept
charged with the water coming from the sink. The hot water bearing the
fat circulates through the three cells and finally, upon reaching a
certain level, passes into the drainage system.
But during its passage through the box the hot water becomes so
effectively chilled as to be compelled to release any fat which it
may be carrying. This congeals and rises to the surface. Within a
short time the top of each cell is crusted with a thick layer of solid
fat which may be removed as frequently as desired. The box not only
constitutes an efficient and simple, as well as inexpensive, fat-trap,
but also acts as a water seal to the sink, thus preventing all nuisance
or fouling of the sink pipe.
The amount of fat capable of being retrieved in this manner is
certainly startling. The fat-trap which I saw fitted to one of the
sinks of an army cook-house yielded several pounds of fat every
day--sheer waste recovered from washing plates, pots and pans. The
fat is dispatched to the swill-mill to be passed through the melter
and extractor in the usual manner, thereby undergoing thorough
clarification and sterilization. The recovery during the course of
the year of several thousand pounds of fat which otherwise would have
vanished down the drain, by the introduction of a small wooden box
such as I have described, represents no mean achievement. Certainly
it serves to bring home the losses which are incurred at this point
in every house during the twelve months. The device might profitably
be installed at every sink by every householder. The few shillings
involved by its provision would be quickly recouped, because the fat
always has a market. Moreover, the introduction of this device would
contribute towards the efficiency of the drain, keeping it clear and
free to fulfil its designed function.
That it pays to recover all fats and greases lost to consumption or
permitted to escape because it is merely residue is conclusively borne
out by the results recorded in connection with the military operations
which I have described. During the year 1917 the fats--waste--reclaimed
from the Home Commands of the British Army yielded 13,000 tons of
tallow. The value of all the by-products recovered from the refuse was
£700,000--$3,500,000. The cost of securing this waste for commercial
exploitation, including the extra pay extended in the form of bonus to
the cooks, and other allowances, was £400,000--$2,000,000--leaving a
balance of £300,000--$1,500,000--which was returned to the public.
As previously mentioned, the fats were urgently needed to furnish
glycerine for the manufacture of munitions. One ton of crude fat yields
10 per cent. of glycerine, so that 1,300 tons of this indispensable
article were derived from this one source of supply. The fat was sold
to the bone-degreasers and the soap manufacturers, who effected the
recovery of the glycerine, selling the product to the Ministry of
Munitions at the agreed price of £59 10s. to £63--$297.50 to $315--per
ton, as compared with £300--$1,500--per ton which we should have been
compelled to pay had we bought the glycerine upon the open market.
Here was a direct saving of £237 to £240 10s.--$1,185 to $1,202.50--per
ton. Altogether the purchase of glycerine recovered from military
organic waste represented a saving of £312,650--$1,563,250--because
the nation obtained for £77,350--$386,750--what otherwise would
have cost £390,000--$1,950,000. This figure is not quite complete
because, inspired by the success achieved from the milling of the
swill at home, the army in France established similar stations
behind the lines upon the other side of the Channel. When these were
brought into operation the shipment of fat and grease recovered
from the organic waste of the British Expeditionary Force in France
represented 5,000 tons a year, whence 500 tons of glycerine were
derived. The 5,000 tons of fat won from the swill-tubs of the army in
France realized £140,000--$700,000--while the total saving recorded
under the heading of glycerine secured from army waste fat was
augmented to £432,000--$2,160,000. During the year in question the
aggregate financial economies directly secured from the exploitation
of organic army waste, in conjunction with the introduction of ways
and means to reduce the yield of such residue from the observance of
improved culinary methods and reduced consumption of foodstuffs was
approximately £5,626,000--$28,130,000. Finally, to demonstrate the
value of this contribution to the aggressive resources of this country,
it may be stated that the 1,800 tons of glycerine derived from the
18,000 tons of tallow recovered from the army swill-tubs, rendered
it possible to turn out sufficient nitro-glycerine to serve as the
propellant charges for 18,000,000 eighteen-pounder shells.
The success accomplished with the army waste fat and grease prompts
the obvious inquiry as to why comparative methods cannot be adopted in
civilian circles. The average household has but little conception of
the value of its fat losses. It should not be an impossible task to
segregate the waste from the house at the source, and to submit it to
similar treatment. The majority of our civic and municipal authorities
possess buildings which could readily be adapted to the installation
of the necessary plant, and the capital outlay therefore need not be
heavy. The disposal of the various by-products would not be attended by
any difficulty. True, under war conditions abnormal prices ruled, but
even to-day they are attractive and are likely to continue to remain so
for an appreciable time to come.
Of course, the municipal authorities could not aspire to net such
profits as are possible in the army. In the first place the wage
problem must be taken into consideration. Under military conditions
this does not arise. Fatigue parties are always available to collect
the swill and to conduct its conversion into fat. But even if the
practice were pursued at a loss it would redound to the distinct
benefit of the community in general, because it would comply with one
of the fundamental laws of National Economy and would conduce towards
the reduction in the cost of living. But unprofitable exploitation
would not result so long as the methods were conducted along commercial
lines. Ineptitude and wastage in administration and operation alone
could be responsible for any such eventuality in this connection.
Happily we are becoming wiser in our knowledge: domestic organic waste
is now being exploited on broader lines, as I relate in subsequent
chapters.