Waste disposal is the gathering, removal, and destruction or use of garbage, rubbish, and ashes. Garbage is unwanted food and waste food materials, such as banana peels, eggshells, and coffee grounds. Rubbish includes rags, wastepaper, and other solid nonfood materials.
Refuse disposal is important to community health and safety. Rats, flies, and other disease carriers live on and in garbage. Concentrations of rubbish can cause fires, and smoke from burning rubbish may pollute the air. Piles of refuse can produce unpleasant odors, and refuse thrown into bodies of water can pollute or contaminate them.
Storage of Waste
Refuse is usually stored for collection wherever it is produced. Garbage should be stored in metal cans that can be closed tightly to keep away insects and animals. Other refuse may be tied in bundles or placed in boxes. Many apartment houses and some private homes have incinerators in which most garbage and rubbish may be burned. In such a case only ashes and noncombustible materials need to be stored and collected.
Collection of Waste
Garbage, rubbish, and even ashes are often collected together. However, when garbage is used to feed pigs or when a disposal method that is inappropriate for garbage is used for rubbish, separate collection is necessary.
Refuse is usually collected in large trucks specially equipped for the purpose. Garbage should ordinarily be collected weekly and at least twice each week during hot weather.
Destruction of Waste
Some localities have community incinerators that destroy refuse cheaply and safely. Such devices produce little smoke if properly operated. Heating the smoke to 1200° F. prevents odors from being spread.
Garbage can also be ground up and disposed of through sewer systems. Some homes have electric garbage grinders in kitchen sinks. These grind garbage into small particles. Some towns have community garbage-grinding plants.
Instead of being destroyed, refuse is sometimes dumped at sea or in designated land areas called dumps. The problems created by dumping, however, make it less desirable than destruction as a means of disposal. If garbage is dumped at sea, some of it floats back to shore. If it is dumped on land, it attracts rats and flies, and disease-breeding conditions, as well as odors, are produced.
Since pigs will eat garbage, an easy and useful method of waste disposal is to feed all edible refuse to pigs. In the United States, Canada, and England, garbage that is to be fed to pigs must be disinfected by cooking in order to prevent the spread of diseases.
Sometimes useful materials, such as metals, are removed from refuse before disposal. This process is called reclamation. In the past some garbage was cooked to produce industrial fats and bases for animal feed, but rising costs and the reduced need for fats have made this process uneconomical. In some countries, such as the Netherlands, chemical processes are used to convert dangerous wastes into harmless humus, which can then be used for growing plant crops.
In the landfill method of waste disposal, dumping and u sing refuse are combined. Garbage and selected rubbish are dumped into large holes or trenches, packed down, and covered with earth. Bacteria destroy the organic matter in the refuse, and the land can then be used.