Millions from Waste by Frederick Arthur Ambrose Talbot - HTML preview

CHAPTER X
 LIVING ON WASTE

War is Hell. So said Sherman, and it is a verdict with which the whole world will agree. But war is also a powerful educating force. If any convincing testimony upon this point were required we have only to reflect upon the effective manner in which the recent European conflagration caused the British nation to revise its methods and practices. The stress of war, ravages by submarines, depletion of transport facilities by sea, road, and rail, and the shortage of crops and labour, compelled the community to consider the food question in a light totally different from that with which it was regarded during the days of cheapness and plenty. We were forced to digest lessons which under normal conditions we would have ignored in contempt. Whether the changes wrought in our complex social and commercial life are destined to be permanent in character is another question, but the continuation of high prices is tending to consummate this end, the process being assisted by the reflection that the good old days are destined never to return, at least not for many years to come.

In the previous chapter I have recounted how the engineer is now striving to conserve rather than to destroy what we throw to one side as of no further use. By inventive ingenuity he is endeavouring to bring home to our local authorities how to extract further utilitarian value from what the household discards. The question immediately arises as to what extent this tendency towards preservation and construction, as opposed to destruction and loss, is being supported in a practical manner by the authorities concerned.

It is to be feared that, considered on the whole, the seeds which are being sown are falling on barren ground. However, here and there our civic and municipal authorities, especially those who evince a distinct pride in being numbered among the pioneers of progress, are fully alive to the possibilities of the problem, and are leaving no stone unturned, nor sparing any exertion, to bring home to the public at large that refuse is merely matter in the wrong place. In some instances this reversion to rigid economical methods is not of modern record, the practice of salvage or recovery of abandoned products having been practised along more or less comprehensive lines, as indicated by scientific thought, for many years past.

The city of Glasgow is able to point to a convincing record of what can be achieved in this direction. In the years 1908-9 the fathers of the progressive Scottish city derived £41,000—$205,000—from this source, while during the ten years ending 1918 what is commonly regarded as rubbish and useless has been induced to yield no less than £50,300—$251,500. Surely what can be achieved in one city is equally possible of attainment in every other community throughout the British Isles to a greater or lesser degree!

Glasgow has evolved its own organization for retrieving and utilising the city refuse and in accordance with the conditions which obtain in the locality. Speaking generally, the system may be described as one of separating the saleable from the unsaleable. Previous to the year 1917 efforts were devoted mainly to the preparation of fertiliser from the contents of the domestic dust-bin, as well as the recovery of tins, but, owing to the high prices which other so-called waste was commanding, and in deference to the national appeal towards greater economy, the reclamation of other materials was taken in hand with highly gratifying results.

The refuse of the city is collected in the usual manner and conveyed to the depot. It is weighed upon receipt. It is then dispatched up an inclined roadway to a tipping floor, where the vehicles discharge their loads through shoots. Beneath the latter are disposed horizontal revolving riddles of conical form. The fine refuse and cinders escape through the grids, but the bulky material is carried forward to be ejected on to a travelling conveyor.

The ashes and cinders which fall through the open mesh of the first riddles are caught by a second and stationary screen. The mesh of this sieve being finer only allows the dust to escape to fall into a mixing machine. Here it is combined with a regulated quantity of excrementitious matter drawn from an overhead tank. The materials are thoroughly blended, and the mixture ultimately falls direct into railway wagons. In this way all intermediate handling is obviated. This material constitutes a first-class fertilizing agent, is keenly sought by farmers, and accordingly meets with a ready sale.

The cinders, arrested by the secondary stationary screen, are collected in a similar manner. They are not sold, but dumped into the bunkers of the works to fire the boilers, thereby assisting materially in the generation of the power necessary to drive the plant.

The bulkier material remaining in the revolving conical grid is discharged on to a conveyor. While being moved forward all material of value, such as waste-paper, tins, scrap-metal, waste-food, rags, bones, glass and so on are picked off by hand to be thrown into bins. The manual labour employed to carry out this task of segregation may be considered to be an adverse cost factor. But against this expenditure for separation by hand must be set that formerly entailed in the destruction or other disposal of this material. Accordingly, all things considered, it may be accepted that the revenue derived from this source virtually represents money saved.

In addition to the recovery of paper from the above-mentioned refuse the Cleansing Department also maintains a special service for the collection of such waste from offices, warehouses, and private residences throughout the city area. This procedure has been in operation for many years, but, owing to the scarcity of paper encountered during the war, and the need which consequently arose to display accentuated enterprise in this direction, an auxiliary collecting service was inaugurated. It was conducted by the members of the Women’s Volunteer Reserve, who received a percentage of the profits arising from the sale of the waste-paper thus gathered.

So far as the waste-metal—light scrap, tins, and other odds and ends of a metallic nature—is concerned this was formerly sold in the form of detinned compressed billets. Under the present contract this is delivered to the contractor in the condition in which it is received. But it is quite possible that, at some future date, there may be a reversion to the baling process which formerly obtained. In view of this fact it has been deemed advisable to bale a certain proportion of the recovered metal merely in order to maintain the hydraulic compressing plant in good working conditions. The practice is to separate and to classify metallic material under one or other of six headings—bright tins, galvanized metal, light iron (black), cast iron, enamelled ware, and burned tins respectively.

While the Cleansing Department hitherto has not devoted any attention to the recovery of garbage from the refuse for conversion into pig-food, it is possible that this issue may be undertaken at a future date. The authorities have the suggestion under serious consideration with a view to its adoption.

The clinker question commands the attention of the Glasgow authorities, as it does all other communities equipped with facilities for carrying out refuse destruction by incineration. But, so far as this city is concerned, the problem does not bristle with perplexity as is invariably the case. The residuum from the furnaces of the Corporation works is mechanically screened into five varying grades, to meet the requirements of contractors who find it eminently adapted to their particular needs. No difficulty has yet been experienced in regard to the disposal of this article, a ready sale always having prevailed for the stocks available.

That the reclamation of the utilitarian contents of the domestic dust-bin is distinctly remunerative to the Glasgow civic authorities is reflected from a perusal of the revenue derived from the recovery and disposal of the city’s refuse during the year ended May 31, 1918. The sales’ record is as follows:—

To the above total there remains to be added the revenue derived from the sale of the prepared manure, arising from the admixture of the finely-screened dust and excremental material. This realized £6,718 17s. 8d.—$33,594—bringing the grand total to £19,188 15s. 1d.—$95,943. In this return the cinders are totally ignored, but, seeing that they constitute a highly serviceable fuel, the saving in the coal-bill, which their use secured, should be taken into consideration.

It is necessary to explain that, inasmuch as the thorough separation of the material is only of recent date, previous operations having been confined to the recovery of paper, old metal and the preparation of the fertilizer as already mentioned, the item “Sundries” cannot extend any criterion as to the results now being recorded, nor of the revenue derived from the recovery and disposal of the additional articles.

The successful conversion of the volume of dust, comprising about 50 per cent. of the aggregate, into a marketable fertiliser, offers a satisfactory solution of a complex and perplexing problem. But when the dust is coarser and yet deficient in “bite” or gritty characteristic, its disposal is not so readily consummated because its possible applications are thereby severely narrowed down in number.

Speaking generally, the utilization of the fine dust may be said to present a vexatious question. While it forms an excellent ingredient for a compounded fertilizer, it is not a simple matter to discover an inexpensive, and preferably second, refuse constituent of approved manurial value with which to associate it. The majority of the ingredients advocated as complying with the desired requirement possess too high an independent fertilizing value for such an application. In itself the dust is of very low soil-feeding power, and so active investigation is being pursued in anticipation of the discovery of a satisfactory adjustment to this question.

Another enterprising illustration of what can be achieved with domestic, office and warehouse refuse, both organic and inorganic, is extended by the Port of Liverpool. Here, again, the developments to be recorded in this connection are not attributable to the war, although the last-named factor was responsible for the conduct of the reclamatory process upon a more intensive scale. Liverpool is somewhat peculiarly situated among the importing centres of the United Kingdom seeing that it is probably the largest distributing centre for American foodstuffs for this country. Consequently, as is only to be expected, very considerable quantities of food which have suffered such damage during transit or demurrage as to become unfit for human consumption have to be handled. Under the old régime all organic waste of this character was either consigned right away to the destructor, or was perfunctorially treated to be sold as manure. Neither science nor brains was displayed in its disposal. The shortest way out of the difficulty was accepted as being the most effective in the public interests. But Liverpool was not the only port to follow such summary practice. It was common to all ports of the country in greater or lesser degree. The public loses heavily from the observance of such deprecatory measures, especially when it is borne in mind that such traffic runs into tens of thousands of tons during the course of the year. But under pre-war conditions, owing to the plentitude of supplies and the wide distribution of the losses incurred, the financial effect was scarcely felt by the unit of the population.

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.

The process is very simple. The refuse is dumped into the digester which, upon being filled, is sealed. Steam is turned on, and the resultant cooking releases all the oleaginous constituents of the contents, which are floated off through the cock to be led to the fat-recovery tanks. The cooking is continued until the raw waste has shed every drop of recoverable oil and grease. The digester is then emptied, pressed, and the cooked material passed to the dryer to be dried, thence to the disintegrator to be pulverized or ground to the required degree of fineness.

The fatty and oil liquors drawn from the digester fall into a tank, and the fat and grease collecting on the surface are skimmed off to be passed to a lower tank. All tanks are kept at a certain degree of temperature by means of a steam-heated coil. The fat and oil reclaimed in this manner are subsequently treated for their yield of glycerine, the final residue entering into the preparation of soap and other articles.

The solid residues recovered from the disintegrator, representing the fibres from the meat, fish offal and other solid matter, constitute an excellent poultry food. According to the analyses which have been made it is rich in the albuminoids and phosphates.

While the foregoing naturally represents the foremost and greatest phase of salvage activity pursued by the Liverpool Corporation it by no means exhausts their efforts in this direction. Other refuse is recovered and treated for some one or other specific commercial purpose. All bones are collected, washed, and boiled to secure the fat, the solid matter afterwards being ground into meal. Vegetable refuse, of which large quantities are forthcoming, especially from the markets, are dried and stored, having been found useful as a constituent for poultry foods. Fish, both offal and unsold inedible surplus, is converted directly into fertilizer. Wooden refuse, recovered from dust-bins and other sources, is heated at low temperature to allow carbonization for sale as charcoal. Large quantities of straw, both clean and soiled, are also brought in, being recovered from packing-cases and crates. The clean straw is segregated to be chopped finely, and as such meets with a ready sale among poultry-raisers because it constitutes a very effective scratching material. The dirty straw, together with soiled paper and old wooden boxes incapable of other treatment, as well as other light refuse, are burned in a special furnace which has been installed, care being observed to collect the ash. As the latter contains approximately 12 per cent. potash it forms a first-class fertilizer. Banana stalks are likewise rich in potash, and so, by submitting the stalks, large quantities of which are forthcoming from the fruit markets under normal conditions, to a special treatment, this potash is recovered and is turned over to the soap-makers. Oyster shells are washed, calcined, and then ground for sale as grit to poultry-raisers.

Damaged and condemned eggs are frequently received in large quantities from the docks, warehouses and wholesale establishments. One consignment numbered no fewer than a quarter of a million. Instead of being used as fuel for the destructor, these eggs are boiled, then chopped, dried and together with the shells are finely ground into meal for use as chicken food.

Consignments of ham and bacon are often received in heavy quantities at times from the docks. This inedible food is submitted to treatment to secure the various commercial by-products such as oil and grease, the residue being ground up into meal.

From the foregoing it will be realized that Liverpool is not permitting much waste of any commercial character to find its way to the incinerator. The wise policy now being pursued is bearing fruit. The prices which have been, and still are being, realized, render the trouble and effort expended well worth while. The meal made from fish offal, after the extraction of the oil, has fetched as much as £25—$125—per ton, while the butchers’ offal, after similar treatment, has commanded an equally satisfactory price. Even the refuse gathered from the households of the city, and capable of being turned into poultry-meal, which exceeds 20 tons a week, is promptly sold at prices ranging up to £15—$75—per ton. The possibilities attending systematic collection from private residences have also been conclusively established, and at the moment the Corporation is gathering a round 1,000 tons of such waste from certain houses in the course of the year. Reclaimed tins, after being washed and dried, have realized up to £8—$40—per ton, while, to meet the enhanced request for organic manure, an excellent fertilizer is being prepared from certain materials which come into the hands of the authorities, or accrue from the practice of waste-reclaiming. The Corporation are able to dispose of this fertilizer with comparative ease at the rate of 50,000 tons during the year.

Other towns are able to point to comparable achievements in connection with the exploitation of waste incurred within their areas. Some of the small communities are even able to produce some startling records in this connection. If all our civic and municipal authorities could be brought into line and raised to the productive level of Glasgow or Liverpool, the cumulative benefits to the nation would be enormous and far reaching. But, as yet, only a fraction of what might be secured is being turned to useful account. For instance, it is computed that 3,000 tons of first-class pig-food could be recovered from London alone every week—this in itself would show a heavy yield of fats and greases if properly treated—but at present it is being wasted.

Merely because foodstuffs—meat, fish, eggs, fruit, and other commodities innumerable of a perishable nature—are condemned as being unfit for the service of man, that is not to say they have completed their mission in the scheme of things ordained by a so-called high civilization. Doubtless they assist in the manufacture of excellent paving-stones, but although we are in dire need of houses and this is the concrete age, that is not a sufficiently reasonable excuse for withdrawing nitrogenous products from the cycle of Nature.