(3) The third class, household garbage and market waste, is the division which causes most trouble and expense in any city, large or small. In seaport towns it has usually been cheapest and easiest to tow the mixed wastes to :AA and tu dump them so far from shore as to be practically unol jectionable. In land cities and towns, however, have found great in disposing organic waste, method of on adopted must at ‘,11.c ...- community and to its neighbors. These municipalities have I usually endeavored to sell their edible waste, even if not very fresh, for use as food in large piggeries. Many, too, until within recent years, have used it as food for mulch cows. The city_ of Worcester, Idass., feeds upward of 2,000 bogs year at the municipal piggerias. Colorado Springs, Denver, Kansas City, Omaha and Providence make a similar disposition of city garbage. At Grand Rapids a contractor pays the city 45 cents per ton and feeds 10,000 hogs; his sales reaching $135,000 a year in pork besides 2,400 tons of highly valued fertilises.
%% hen mechanical methods were sought, the first impulse naturally was to destroy an article which had been the source of so much danger and trouble; the second impulse was to save a substance winch was known to be valuable. The development of these two ideas has led to the invention of incinerating and utilisation meth ods, respectively. The term garbage is used here to signify only table, kitchen and market refuse, consisting of animal and vegetable scrap. always wet and putrescibie. The composition of this material varies with the season and with the city, but the average in America is approxi mately: Water, 70 per cent; grease, 3 per cent ; solid fibre, 27 per cent. Such material cannot be burned until its 70 per cent of closely-held water has been freed and evaporated; and, on the other hand, its grease and fibre have com mercial value if they can be separated from the water and from each other.
Every housekeeper knows that small amounts of garbage can be quickly disposed of by a good fire; but when the endeavor is made to destroy a large- amount of _garbage. by .a 'peer lire;. the trouble begins. In all cases noxious fumes are produced and escape unless the temperature is 2,000° F. or more, and freedom from offensive odors is gained only at the expense of fuel. The organic fumes must be decomposed and destroyed within the furnace itself and, there fore, the process must be one of complete com busuon and not mere evaporation or distilla tion. When a small amount of garbage is mixed with a large amount of paper, excelsior, shop sweepings and waste coal and dinker the in cineration process is neither difficult nor costly; and is permissible in the outskirts of a town or city where there are no neighbors within a mile to be troubled by the fumes which in practice always escape with the chimney smoke and come to the ground at a greater or lesser distance ac cording to the force of the wind. Many city in cinerators for this kind of waste destruction are in use in the United States and Canada; many of practically the same class have been in use in England for a long time, and from there the practice has extended to Hamburg and some other places; but none of these incinerators en deavor to burn pure garbage, but always the mixture above mentioned. As a matter of fact,
there is enough heating power in a pound of dry garbage to evaporate the water from the next pound, and, therefore, there is no reason why a furnace cannot be so constructed that each pound of garbage may dry the next succeeding pound, and garbage thus be made to burn itself, with only enough added fuel to insure the destruction of fumes. The practice in cities which use in cinerators is to collect household ashes with the garbage. These ashes average 20 to 25 per cent of unburned coal, and this is ample for the complete destruction of the garbage at a suitable temperature.
Garbage utilization processes all aim to ex tract the grease by cooking in steam or solution in naphtha, after which the solid material or fibre is dried and ground to form a fertilizer base. The recoverable grease amounts to about 60 pounds per ton of raw garbage, and is salable at about three cents per pound. The dry fibre averages 540 pounds per ton of winter garbage and derives its value from the presence of am monia-18 pounds @ 8c. —$1.44; phosphoric acid— 18 pounds ePt Ic.°18c.; potash —6 pounds @ 3Y2c.-21c., or a total recoverable value of $3.63 from a ton of raw winter garbage. Summer garbage is less valuable because tt contains more water and less grease and fibre. The cost of treatment, when the quantity is large, is less than the value of the material re covered. In American cities the amount of garbage collected averages about a half pound per citizen per day; in Europe it averages less than a quarter pound. Many people object to keeping separate garbage cans because of the odors which arise unless the water is absorbed by a mixture of ashes, paper and other waste; but in a large city where garbage is collected daily, it is evident that material which has come from the table within 24 hours must be odorless and unobjectionable, and that the odors arise solely from the cans, and from them only be cause they are not regularly washed and kept clean. Some cities require the wrapping of garbage in substantial paper parcels. This not only makes for deanliness but renders incinera tion very much easier. The pee capiwproduc tioo of -garbage is the. United -States- wanes from AO pounds (Buffalo, N. Y.) to 260 pounds (Rochester, N. Y.) per annum. In nine of the larger American cities the daily output of gar bage varies from 331 pounds to 875 pounds per 1,000 of population. In 1914 the city of New York entered into a contract by which it was to receive $62,500 for its garbage the first year; V7,500 the second year; and $112,500 annually for three years thereafter.