Waste sorts were conducted during each of the four quarters (or seasons) of 1996 at the City of Columbia Sanitary Landfill. A detailed physical sampling protocol was outlined. Weight fractions of 32 waste components were quantified from all geographic areas that contribute to the Columbia Sanitary Landfill using a two-way stratification method, which accounted for variations in geographical regions and seasons. Comparisons of solid waste generated between locations and seasons were conducted at the 80% confidence level. The composition of the entire waste stream was 41% paper, 21% organic, 16% plastic, 6% metal, 3% glass and 13% other waste. Paper was the largest composition and glass was the smallest composition for all geographical regions. The result of this study was also compared with a 1987 Columbia, Missouri study conducted by EIERA (1987), with studies conducted in other states such as Minnesota, Wisconsin, Oregon and with national study conducted by the USEPA (USEPA 530-R-96-001, PB96-152 160. US Environmental Protection Agency, Office of Solid Waste, Washington, DC). The results of studies from other states are different from this study due to different local conditions, different methodologies and a different scope. There was a small (5%) increase in per capita weight from 1987 to 1996. The total per capita weight in the present study was 60% greater than the national per capita weight reported by the USEPA (1996) due to that the USEPA report excluded industrial, construction and certain commercial waste. The total per capita weight agrees with the national per capita weight for municipal waste reported by Tchobanoglous (1993), which included industrial, construction and commercial sources. The geographical and seasonal effects on the waste composition are evaluated and discussed. Statistical analysis indicates that waste characteristics are different among geographical regions and seasons. The potential for waste recovery and reduction is also discussed.

Solid waste management planning involves selecting a best combination of solid waste management options. The decision involves the perceptions and preferences of different groups of people and multiple, sometimes conflicting, project objectives that are expressed in subjective terms. As reported in this paper, these issues were addressed by developing a fuzzy multicriteria decision support system. An internet-based user-interactive decision-support application was developed based on fuzzy logic. Community specific data are stored in a centralized database and are accessible to others through a web browser. The decision support system is a tool for decision makers and environmental professionals to use in conducting local and regional integrated solid waste management planning. A case study was conducted to illustrate the application of the models. The case study evaluated eight alternatives for managing the waste stream entering the City of Columbia Sanitary Landfill and utilized waste characterization data, other solid waste related data from the City of Columbia and the open literature, as well as preferences assigned by the researchers. The results showed that an assigned Alternative 4, which is a combination of Material Recovery Facility (MRF) and Refuse-Derived Fuel Facility (RDF) could be distinguished as the alternative that best met the established criteria. The sensitivity analysis showed that the fuzzy ranking results were not sufficiently sensitive to the different aggregation operators for combining the fuzzy importance factors. The comparison of different composition operators showed that the sum-product composition operator allows greater differentiation in the solid waste management context.

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