It would scarcely be possible to name in this connection all those who have contributed to the development of principles, systems and ap paratus which go far toward the practical solu tion of this difficult problem. Boston installed the first modern refuse-sorting plant, and the first reduction plant was at Buffalo. Much im petus was given to effective practical develop ment of the principle of utilization by the deter mined efforts of the late Col. Geo. E. Waring, New York's indomitable commissioner of streets. After a most exhaustive investigation of the whole subject, and a thorough inspection and test of every system of disposal then in exist ence, both in Europe and America, Colonel Waring became thoroughly convinced that utilization was right in principle and practice, and proceeded at once to have the garbage of the city of New York disposed of in this manner.
Prior to this time there were successful utilization plants in Philadelphia, Pa., Saint Louis, Mo., and Detroit, Mich. The system adopted by Colonel Waring, and which is now in use in many of the principal cities of the United States, is first, thorough sterilization by subjecting the material to the action of live steam in enclosed vessels, condensing all vapors and passing insoluble gas through flame. By this treatment the structure of the material is broken down,— even bones are disintegrated,— the liquids carrying the oils and greases being separated from the solids by mechanical means. The further preparation of the ingredients, by which they are put in commercial form or finally disposed of, varies greatly in the different plants. In some cases the liquids are evaporated, in others they are allowed to run into sewers or water courses. In a number of the plants the solid portions are used for fuel; in others they are acidulated or dried and prepared as a base for commercial fertilizers. The greases are sometimes extracted by the use of a solvent, and reclaimed by evaporation, the solvent vapors being condensed and also reclaimed to be used again. The principles involved are not new, having been applied for many years to the treat ment of slaughter-house waste. In its applica tion, howeier, to the greater subject of garbage disposal, much new apparatus has been invented, and the plants have been equipped to handle very promptly a vast amount of the material; the plant which disposes of the entire garbage of the Greater New York having a daily capacity of more than 2,000 tons, and the plants lo cated in Philadelphia, Pa., Boston, Mass., New ark, N.. J., Baltimore, Md., Washington, D. C., Detroit, Mich, Saint Louis, Mo., Cleveland, Ohio, Columbus, Ohio, and in some of the smaller cities, are of sufficient capacity to dispose of all the garbage produced within 12 hours of de livery at the plant. It is this prompt and effect ive disposal that has rendered the utilization systems so popular in the large American cities. The entire work of collection and disposal is, in most cases, done by contract. The plants are owned by contractors, the cities in some cases collecting the garbage and delivering it upon the contractors' cars or boats for trans portation to the place of final disposal.
Garbage collection is now common in all American cities and towns of 10,000 or more population, and is increasing in smaller places. It has been found that a collector making rounds once a week can serve 40 to 90 houses a day. Usually two men travel to a wagon, and the use of specially designed sheet-iron body wagons is increasing. • It is common to ask house holders to separate their garbage and ashes and refuse in separate cans, so that the collectors can conveniently dispose of them. The ashes
can then be used for filling low land, which would be impracticable if mixed with garbage. Where there are incinerator plants there is a tendency to return to the old method of dumping all the garbage, ashes and refuse together, and i taking it to the incinerating furnace. Here the unburned coal in the ashes and the wood in the refuse furnish fuel enough to consume all the moist garbage. Cities and districts are routed, and householders notified what days the collectors will come through their streets, and on such mornings they place their garbage cans on the sidewalks.
Incinerators or destruction plants are increas ing in use. Seattle has five 60-ton destruction plants, distributed so as to reduce haulage, and pays $1.94 per ton for collecting the garbage. Incineration costs only seven and one-half cents a ton. Figuring in depreciation, interest and all costs, the total expense is about $3 per ton. One of the largest incinerator plants is in Columbus, Ohio; capacity 80 tons in 12 hours. The garbage is collected in steel wagons, 50 horses being employed in the hauling. Ashes are utilized to fill in low land ; the garbage collectors deliver to railway garbage cars, of which there are four, built at a cost of $1,890 each. These cars deliver over the trolley line to a plant four miles out, where the garbage is drained, the water being evaporated. The solid residue goes to digester tanks for treatment with hot steam at 60 to 70 pounds pressure for six hours. It is then pressed and the grease separated, as much as 400 tons a year being obtained and sold; the remainder of the solid product is pressed into cakes for fertilizer. This Colum bus plant cost the city about $200,000 and the collection system about $100,000. It disposes of the garbage and ashes at a total cost of about $3 per ton.
Many of the failures, both in incineration and utilization, are due to the improper location of plants. While it should be perfectly clear to everyone that such plants should be so located as to cause the least possible property loss or inconvenience to the people, yet it should be recognized that every city must have a place i for final disposal of its waste and, once prop erly located, it must be recognized as such. Though plants for final disposal, when properly designed and operated, have not proved a nuisance to near-by residents, nor a menace to public health, yet the assembling at one point of the material is objectionable and should be restricted to a section for such purposes. See WASTES, CITY, DISPOSAL OF.
Much has 'been written on the subject by both European and American engineers, prin cipally in the form of papers read before some of the engineering societies, and published in engineering journals. Valuable information can be obtained from the files of such journals. Very little of such material, however, has been put in book form. In a small volume published in 1897, entitled 'Street Cleaning and Its Effects,' by Col. Geo. E. Waring, interesting and valuable data is assembled, a portion of which bears directly on this subject. A most comprehensive treatise on the subject is 'The Wastes of a Great City,' by John McGaw Woodbury, commissioner of street cleaning, New York in Vol. XXIV, p. 387, Scribne?s Magazine (1903). Consult also Venable, 'Gar bage Crematories in America' (1906) ; Morse; 'Collection and Disposal of Municipal Waste' (1908).