Environmental Engineering Reference
In-Depth Information
waste. Despite improvements in waste reduction and recycle, MSW management
remains a constant concern because the generation trend indicates that the overall
tonnage we generate continues to increase, especially for developing countries.
The amount of MSW generated in United States increased 60 percent from
1980 to 2006. In 2006, U.S. residents, businesses, and institutions produced more
than 246 million tons of MSW, which is approximately 4.5 pounds of waste per
person per day (U.S. EPA 2007). Paper and paperboard products constitute about
34 percent of the MSW stream. This is the largest portion of MSW. In 2006,
Americans generated about 85 million tons of paper products, which are nearly
a threefold increase from 1960. About 52 percent of all paper and paperboard
products were recovered in 2006, nearly two and a half times the percentage in
1960 (U.S. EPA 2007).
Municipal solid waste is collected by cities and counties and then potentially
separated into three waste streams. These waste streams are then processed as
follows. Recyclable material is separated by category (paper, glass, aluminum,
etc.) and then sorted and sold to brokers or vendors. Organic wastes such as
yard wastes can be composted using microorganisms to produce a humuslike
substance, which can be used in gardening and landscaping applications. The
remaining waste stream is often placed in a landfill or sent to incinerators. The
major legislation that governs the management of solid waste is the Resources
Conservation and Recovery Act (RCRA) of 1976. The intent of this legislation is
to promote environmentally sound solid waste management practices to maximize
resource recovery. It has been amended about every couple of years. RCRA
gives the legal basis for implementation of guidelines and standards for solid
waste storage, treatment, and disposal. In this legislation, the U.S. EPA separated
hazardous waste from municipal solid waste so that hazardous waste is regulated
under Subtitle C and solid waste is under Subtitle D. Although solid waste is
regulated mostly by state and local governments, the U.S. EPA has promulgated
solid waste regulations to address how disposal facilities should be designed and
operated. Its primary role is in setting national goals and providing technical
assistance, as well as developing educational materials.
Management of municipal solid waste is a complicated problem that must
be addressed to meet public health, environmental, and economical concerns.
The U.S. EPA's tiered integrated waste management strategy includes the fol-
lowing: (1) source reduction (or waste prevention), including reuse of products
and on-site (or backyard) composting of yard trimmings; (2) recycling, including
off-site (or community) composting; (3) combustion with energy recovery; and
(4) disposal through landfilling or combustion without energy recovery. The rest
of this chapter will discuss the following aspects of MSW: sources and composi-
tions, management processes that includes source reduction, collection, recycling,
composting, incineration and landfilling, management in other countries, plan-
ning issues and optimization models development, environmental impact and
life-cycle assessment, and future trends in MSW management.
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