During the war a loud wail went up because a number of hams and a quantity of bacon had been found in a decomposed condition at a certain port. Had this occurred during pre-war days not a word would have found its way into the public press, and the destructor alone would have known of the incident. But because under war conditions the public was directly affected—was clamouring for this particular article of food—the wastage was declared to be intolerable. Fortunately, in this instance, owing to our having become more enlightened, the spoiled food was not totally lost. The fat was reclaimed, while the residue was turned to its most profitable account.
At Liverpool, as at other centres where a vigilant eye is maintained upon the clock of progress, it was speedily discovered that the methods of handling such refuse were distinctly deprecatory. It was decided to introduce improved practice. One material was treated as an experiment, and the process was found to be profitable. Gradually other condemned articles of food were taken in hand. This logical development of salvage was continued, until to-day there is very little material entering into the composition of the Liverpool dust-bin which does not find some one or other useful application.
It was learned from studied investigation that waste-food products collected with the refuse of the city might be classified into five broad divisions, namely butchers’ and fishmongers’ offal, damaged fruit and vegetables, damaged eggs, damaged canned foods, such as meat, fish, milk and so forth, as well as warehouse sweepings. Over and above this assortment, of course, came the miscellany to be found in every ash-bin drawn from the home. To ensure the receipt of the offal from tradesmen a special and separate collection from all retail shops dealing in fish and greengrocery was inaugurated. Subsequently, to prevent the wastage of swill suitable for the sustenance of pigs, a special collection from private houses was introduced.
In every city the isolation of the swill from the general material consigned to the dust-bin though freely urged is a somewhat difficult issue to carry into practice. Segregation at the source is imperative to ensure the maximum results being attained. But the Liverpool authorities overcome the obstacle very satisfactorily. The residents were notified of the intention of the department charged with this duty, while officials were detailed to visit and to explain to residents the proposals, and to extend advice upon what, and what should not, be thrown into the dust-bin. Moreover, the City Fathers undertook to provide each house with a special receptacle for the swill, and to collect it at frequent intervals. Experience proved that collection twice a week sufficed to meet every requirement.
But, as a rule, when the suggestion is made that local authorities should provide special receptacles for swill, demur is made on the plea that such a procedure must entail further capital expenditure. Yet it can be carried out along very inexpensive lines if attacked in the proper spirit. So far as Liverpool has been concerned it was even found possible to turn a waste article to such account. Among the flotsam and jetsam sent to the corporation depots for disposal were thousands of tins measuring 9 × 9 × 13 inches, originally used for the conveyance of oil to this country. Examination revealed the circumstance that these discarded receptacles could readily be converted into swill-pails, their dimensions and construction admirably adapting them to such a duty. Forthwith they were cleaned, one or two minor alterations carried out, and then painted. The cost of adaptation was less than 1s.—25 cents—per tin. These were then issued to the residents who expressed readiness to co-operate with the efforts of the authorities, and proved a complete success. It has often been advanced by local authorities that the residents will never collaborate in such schemes of segregation at the source, declining to be bothered, but the experience gained at Liverpool does not support such a contention. The inhabitants of the city astride the Mersey responded very promptly to the request to save and segregate their swill, the result being that enormous accumulations of potential and valuable pig-food were secured.
Swill supplies being assured, the next step was to handle this waste at the depot, and to prepare it for the piggeries. The City Engineer, Mr. John A. Brodie, M.Inst.C.E., advanced a complete solution to this problem and along economical lines. A number of old pitch boilers and other plant was lying idle at the depot. This was turned out, overhauled, rigged up and coupled up to the steam generating equipment of the destructor. The household swill was cooked in these vessels, and in this manner a first-class pig-food was produced. To ensure the consumption of the swill thus obtained the Corporation installed its own piggeries and poultry runs upon its farms. The swill, while still hot, was conveyed to the piggeries in the municipal motor wagons and doled out. Private pig-raisers were also at liberty to obtain the swill in the heated condition if they cared to fetch it. This facility was readily accepted, inasmuch as it saved the pig-keepers the trouble and time of conducting collection from houses in the conventional manner and then boiling it upon their farms for their animals.
Continuous development of the reclamation of waste problem has been the policy of the Liverpool civic authorities. Satisfied with the pecuniary and other results attending their initial efforts the City Engineer installed an inexpensive and complete plant working upon the Scott system, described in another chapter, for the full reclamation of the material contained in the city refuse. It was laid down at the central depot primarily to treat the meat, fish, and other organic offal, increasing quantities of which were forthcoming. The plant in question comprises a digester, dryer, vacuum pump, disintegrator and fat tanks. Electric drive is employed throughout, the necessary power being drawn from the municipal generating station.
The digester, made of steel, 7 feet long by 3 feet in diameter, is of sufficient capacity to receive one ton of refuse at a time, and works at a pressure of 60 lb. It is charged from the top and emptied from the bottom. It works upon the jacket principle, and the necessary steam may be admitted both at the top and bottom as desired. Top and bottom cocks are fitted for drawing off all fatty and oily liquid for the fat tanks, and also to draw off the liquor. About four hours are required to treat the charge.
The vacuum dryer is a drum, 4 feet 6 inches deep by 5 feet in diameter, and is also able to receive a charge of one ton. Top and bottom facilities, for charging and emptying respectively, are provided. Within the vessel rotating blades are disposed to keep the contents in agitation during treatment, these blades making about 25 revolutions per minute. All foul gases arising during the process are drawn off by a vacuum pump, and are led to the furnaces to be consumed, thereby being rendered innocuous before escaping into the atmosphere.
The disintegrator is a cast-iron cylinder provided with a continuous automatic feed. Within the vessel are set a number of steel arms which run at a very high speed—about 2,500 revolutions per minute—which break up and thoroughly disintegrate the refuse introduced until it is able to pass through the meshes of the screen placed at the bottom of the machine.