Chapter C: O. Bartlett, sanitary engineer, says: “So far as disposal of garbage

is concerned, in incinerators, it is coming to be generally understood that this method is far from sanitary and is essentially wrong in that it neglects to obtain the value for the products so collected.”

Rudolph Herring, Sanitary Expert, says: “In incineration, if sufficient fuel is added, the combustion can be made perfect and the garbage can be destroyed without offense and converted into inodorous gases, ashes and clinker. Whatever sanitary objection has been made to this process has resulted from preventable causes. Unless ashes and rubbish are combined with garbage in sufficient quantities to produce the necessary heat, the steam production is deficient and other fuel must be added.”

Robert H. Wylde favors incineration at a high temperature: “Here we have a method that is at once sanitary, expeditious and economical in first cost and maintenance.” He also says that this method is free from nuisance, the plant may be centrally located, cost of collection minimized owing to the relative shortness of hauls, not necessary to maintain a separate collection, nor is there any necessity to keep refuse in separate cans.

W. F. Goodrich, Sanitary Expert, maintains that modern destructors are perfectly satisfactory and that there may be no fear of nuisance wherever they are located. He maintains that it should be the aim of officials to utilize the power produced for the best interests of the community.

William M. Venable believes that cities of from 10,000 to 40,000 population should burn garbage and refuse, the problem to be solved being the advisability of attempting to utilize the heat generated by burning.

Reduction

When the reduction method is used only garbage and dead animals can be destroyed, but when these kinds of wastes are broken down by means of heat, valuable by-products are recovered. This may be done in two ways, the processes being known as cooking, or digestor system, and drying. In the first, garbage is cooked in large closed retorts by means of steam under pressure. It is then pressed, leaving grease and a dry cake known as tankage, which is used for fertilizer. In the drying method the grease is extracted by some volatile solvent like naphtha. The relative advantages of these two methods is disputed. At the present time the majority of plants are operated by the cooking or digestor method.

Within the last year or two a new reduction process has been evolved. The raw garbage is placed in sealed, air-tight tanks with jacketed walls and bottom. The solvent is pumped into the reducer and steam admitted to the jacketed walls. The heat causes the evaporation of the solvent and the water in the garbage. When the garbage has been dried, the solvent is pumped into the reducer and dissolves the grease. In an evaporator the solvent is vaporized and carried to a condenser where it is again liquefied and then conveyed to storage tanks. After the extraction of the grease, the garbage is further dried by steam, and as tankage, is used for fertilizer. The chief advantage claimed for this system is that it is odorless. The cost of plant operation is much greater than that of the digestor system, but the value of the recovered products is considerably greater. Plants of this type are being operated in Los Angeles, Cal., and in New Bedford, Mass. The plant now being constructed for handling the garbage of New York City will also employ this new process.