Introduction

Waste: v. to use, consume, or expend carelessly or thoughtlessly without need; n. a worthless or useless byproduct. (Webster's, 1984)

Wastes from manufacturing, agriculture, mining, oil and gas production, and municipal sources (residential, commercial, and institutional) must be managed. The preferred management technique, all other things being equal, is source reduction; however, wastes are inevitable in any activity. A waste management system is used to collect, transport, and manage the disposal of waste. The management system may include any combination of disposal on land, in air, or in water, or utilization as fuel or material. In each case the economic, environmental, and energy issues must be considered in a life cycle analysis. Today, most people believe that the common method of waste management is by discard to the environment, usually to a landfill, although incineration (discard to the air) and discard to water are also practiced. Yet, historically humans have used wastes for productive purposes. Cities are, in part, constructed from older structures. Even today estimates are that 50% of the primary metal used annually in the United States is produced from scrap and wastes. A limited database of information exists for evaluating the relative merits of these options, particularly as they relate to industrial wastes. The largest body of knowledge is for municipal solid waste (MSW).

There are significant environmental advantages to the productive use of wastes. Using wastes productively reduces their discard to the environment and displaces other fuels or raw materials with their associated concerns. Despite such environmental advantages, permitting is often delayed or projects rejected because of misperception, the lack of comparative fuel cycle based data, the need for improved technology, and high first cost versus excellent life cycle cost.

The consequences of any decision relating to economics, environmental concerns, or energy systems must consider the full breadth of the impacts including mining, refining,

Legend Manufacturing Agricultural —

2.5

Oil and Gas Hazardous Municipal

CD Mining

Oil and Gas Hazardous Municipal

Figure 1 Waste disposal in the United States (in billions of tons).

collecting, transporting, utilizing, and, ultimately, waste disposal. For example, the conversion of MSW into energy reduces the amount of waste going to landfills by 90%, reduces landfill gas emissions identified as greenhouse gases by a factor of 15, reduces the need for other conventional energy sources and their associated emissions, and provides an indigenous energy source while producing air emissions (at lower than the rates for criteria pollutants for some displaced alternatives) and benign ash for disposal. Recycling reduces the amount of waste going to landfills, eliminates landfill gas emissions associated with biodegradable materials, and may conserve conventional energy sources and their associated emissions but produces air emissions from added transportation and manufacturing.

There are a variety of sources of information on waste generated in the United States although they are generally inadequate for estimating potential for reducing or using the waste resource. Based on an analysis of available data from a variety of documents, Americans generate roughly 14.7 billion tons of solid wastes per year. By far the greatest portion of these wastes are classified as nonhazardous manufacturing wastes, accounting for just under 60% of the total waste stream by weight. Hazardous waste, which is the focus of most data collection efforts, represents roughly 6% of the total. The balance of industrial wastes are agricultural, oil and gas, and mining wastes.

Figure 1 presents the estimated amount of each waste stream and its contribution to the total. The total of 14.7 billion tons represents a reasonable conjecture of the total industrial and municipal wastes generated in the United States, but it is by no means a precise figure because of a number of imperfections in the data collection and analysis.

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