Municipal solid waste (MSW), also called household solid waste, is a waste type that includes predominantly household waste with sometimes the addition of commercial waste collected in a given area. They are in either solid or semisolid form and generally exclude industrial hazardous wastes. The term residual waste relates to waste left from household sources containing materials that have not been separated out or sent for reprocessing. Composition of MSW: food wastes, paper, cardboard, plastics, textiles, leather, yard wastes, wood, glass, metals, ashes; domestic hazardous waste: medicines, paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and pesticide containers, batteries, shoe polish; special wastes (e.g., bulky items, consumer electronics, white goods, oil, tires).
The functional elements of solid waste chain:
Waste handling and separation, storage and processing at the source: Waste handling and separation involves the activities associated with management of waste until they are placed in storage container for collection. Handling also encompasses the movement of loaded containers to the point of collection. Separation of waste components is an important step in the handling and storage of solid waste at the source.
Collection: the functional element of collection includes not only the gathering of solid waste and recyclable materials, but also the transport of these materials, after collection, to the location where the collection vehicle is emptied. This location may be materials processing facility, a transfer station or a landfill disposal site.
Separation and processing and transformation of solid wastes: the types of means and facilities that are now used for the recovery of waste materials that have been separated at the source include curbside collection, drop off and buy back centers. The separation and processing of wastes that have been separated at the source and the separation of commingled wastes usually occur at a materials recovery facility, transfer stations, combustion facilities and disposal sites.
Transfer and transport: this element involves two steps: i) the transfer of wastes from the smaller collection vehicle to the larger transport equipment ii) the subsequent transport of the wastes, usually over long distances, to a processing or disposal site.
Energy Generation: municipal solid waste can be used to generate energy. Several technologies have been developed that make the processing of MSW for energy generation cleaner and more economical than ever before, including landfill gas capture, combustion, pyrolysis, gasification. While older waste incineration plants emitted high levels of pollutants, recent regulatory changes and new technologies have significantly reduced this concern. For example, in the US EPA regulations in 1995 and 2000 under the Clean Air Act have succeeded in reducing emissions of dioxins from waste-to-energy facilities by more than 99 percent below 1990 levels, while mercury emissions have been reduced by over 90 percent. The EPA noted these improvements in 2003, citing waste-to-energy as a power source "with less environmental impact than almost any other source of electricity".
Disposal: today the disposal of wastes by landfilling is the ultimate fate of all solid wastes, whether they are residential wastes collected and transported directly to a landfill site, residual materials from materials recovery facilities, residue from the combustion of solid waste, compost or other substances from various solid waste processing facilities.
A modern sanitary landfill is not a dump; it is an engineered facility used for disposing of solid wastes on land without creating nuisances or hazards to public health or safety, such as the breeding of fatties and insects and the contamination of ground water.
The problem of solid waste is gigantic. Only the United States generated in 2008 about 250 million tons of solid waste. Solid waste management has always been a chronic problem in all parts of the world, causing serious environmental degradation. Uncontrolled dumping and burning are the common methods practiced for solid waste disposal resulting in serious land, water, and air pollution problems. Although such methods are legally banned and their adverse impacts widely recognized, until the present time, they are still practiced in rural areas and even in some urban areas, mainly due to the lack of law enforcement, financial means and awareness. Sole solution of the problem is efficient solid waste management. State-of-the–art waste management policy is based on a hierarchy of principles: best is waste prevention with disposal as least favorable.