Waste management involves the collection, transport, processing, and recycling or disposal of solid, liquid and gaseous wastes in a manner that is ecologically sound. The waste management industry is comprised of those entities charged with this task. In many localities, waste management is conducted by private companies either directly or under contract to a local government, while other jurisdictions handle waste through local government agencies.
Traditionally, solid waste was collected from consumers and hauled off to a landfill. As the amount of municipal solid waste (MSW) has grown, concern over disposal methods has increased. Not only is there a shortage of landfills in some areas, but scientific advances have revealed a number of environmental concerns regarding contamination from untreated landfills. In addition to finding alternative methods of disposing of MSW, the waste management industry has revised its landfill management. Landfills in the US and many other regions now have clay liners, and the garbage is spread, compacted, and then covered with dirt daily.
The waste management industry has also become the global leader in recycling. Japan has perhaps the best success record to date, with over 70% of all municipal waste recycled. In the US, this amount is approximately 33%, and in the UK the total is a little over one-quarter of the MSW produced. Not only does recycling reduce waste disposal, but it saves production energy.
There are a number of other disposal options used by the waste management industry to reduce the need for landfills. Incineration is a mature technology, but some plants are now equipped to convert the waste they burn to energy in the form of heat, electricity or gas. Many of these facilities sort out the recyclable products first, and then use the heat from the incinerators to convert water to steam to run the plant, or to produce electricity. Japan has been very successful in using energy from waste processed at advanced thermal treatment (ATT) plants to supply some of their municipal power needs. Large scale ATT plants have also been build in Europe and North America
Waste can be treated with heat, chemical, biological and physical processes. One biological disposal option being explored by the waste management industry is the use of aerobic digestion. In 2002, the Thomley waste transfer station in County Durhan, UK, opened with two aerobic digestion towers. This plant processes unsegregated MSW, successfully diverting over 70% of the waste processed from landfills or incinerators.
Some sectors of the waste management industry specialize in the disposal of hazardous, toxic or medical waste. These companies deal with asbestos removal, toxic site cleanup, and disposal of substances which cannot be deposited in a landfill. Many countries and local governmental agencies have specific regulations requiring disposal of such items. These usually involve treating the waste in such a manner to render it harmless or at least less toxic, as well as the method of final disposal. Toxic liquid wastes are often deposited into underground injection wells which are highly regulated to prevent contamination of drinking water.