Physical and Chemical Characteristics of Selected U.S. Municipal Solid Waste Composts
- Xin-Tao He *,
- Terry J. Logan and
- Samuel J. Traina
Municipal solid waste (MSW) composting has been increasingly recognized as a promising alternative for solid waste management. Because of the variation in both geographic origin (thus feed stock) and composting technology, the properties of MSW composts generated in various regions are likely to be different. In this study, 10 composts were collected from different facilities throughout the USA. Elemental composition and some physical properties were determined. Trace elements and organic C were partitioned into water soluble, exchangeable, complexed, organically bound, mineral particulate, and residue forms based on sequential extraction with H2O, 1 M KCl, 0.1 M Na4P2O7, 0.1 M NaOH, and 4 M HNO3, respectively. Substantial variabilities were observed in both chemical and physical properties among the MSW composts generated in different facilities. Our results indicate that the trace element contents of MSW composts are in general lower than the average trace elements reported for sewage sludges, and below the pollutant concentrations (PC) for sewage sludges regulated by USEPA. The exception is for Pb, which was higher in some of the MSW composts than the average Pb content in sewage sludges and exceeds the PC. Solid particulate was the dominant form of Cd, Mn, Cu, and Pb, but the majority of Zn was organically complexed. Both solid particulate and residue were dominant forms of compost Cr and Ni. The differences in distribution patterns of trace elements in the MSW composts studied indicate that these elements will vary in their potential mobility and bioavailability in the environment.
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