Waste disposal system

The problem of waste management and disposal becomes increasingly pressing as human population, industrial activity, and material consumption expand. The collection and disposal of municipal wastes poses the most visible solid-waste management problem; agricultural and mining wastes, however, dwarf urban wastes present a severe danger to the environment

Agricultural and Mining Wastes. Agricultural and mining wastes are generally disposed of on the land from which they came. When not adequately contained, however, these wastes have caused the contamination of runoff and receiving waters. Agricultural wastes, particularly animal wastes, contain valuable nutrients that traditionally were returned to the soil. Recently, however, agricultural wastes have come to be seen as a disposal problem rather than as a usable commodity.

As the cost of chemical fertilizers increases, the residuals from organic-waste treatment, or the untreated wastes themselves, may once again become a significant source of soil nutrients.

Industrial Waste. Hazardous industrial waste, although often in liquid from, are generally treated the same as solid waste because they must be kept from receiving water. Radioactive or chemically toxic waste must be adequately contained in special disposal areas.

Municipal Waste. The residential and commercial wastes of municipalities cause litter, open dumps, leaching of water pollutants, ocean contamination, air pollution from burning wastes, and wasted resources. Before the 1960s most of the urban refuse produced in the United States was burned in open dumps or in inadequate incinerators. Today, most municipal waste is buried in sanitary landfill. Many landfill, however, are nearly filled, and are closing.

Urban refuse contains large quantities of potentially usable paper fiber, glass, metals, organic material for compost, and energy. A traditional urban waste-disposal method is incineration, which reduces the volume of the water by about 90%. Drawback to incineration include air pollutant and the disposal of the residue, or “fly ash” that remains after the incineration process.