Characterization of changes occurring in natural organic matter during the composting of a synthetic compost and a municipal solid waste.

摘要

Composting has the potential to recycle natural or organic matter regarded as a wage product while forming a productive soil amendment. Humic substances are believed to form during the composting process. These ubiquitous compounds impact the fate and transport of metals and organics as well as trihalomethane formation.; The objectives of this research were to investigate compost and humic substances; and the pyrolysis-gas chromatography/mass spectrometry (PY-GC/MS) method. Two composts were investigated during 120 days of a composting process: synthetic compost and municipal solid waste compost. Both composts were divided into several operationally defined fractions: extractable, matter, fulvic fraction, humic acid, fulvic acid, nonhumic substances and nonextractable matter. Extractable matter was further separated into several apparent molecular size fractions.; The intact material (whole compost) for each of the composts was investigated in terms of the changes occurring in gross physical parameters: moisture, organic matter, and ash. Humic acid became more dominant as composting progressed. Fulvic acid and nonhumic substances showed decreases. Synthetic compost had much greater levels of all humic fractions than did municipal solid waste compost.; Synthetic compost exhibited little change in reactivity as the result of compost but did show a change in molecular size. Municipal solid waste compost showed noticeable changes in reactivity but little change in size. The trend is for smaller molecules to form as composting progresses.; Apparent molecular size determination was also ran. Extractable matter fractions were investigated. Synthetic compost showed the greatest change in size of molecules. Most noticeably, the smaller molecular weight compounds disappeared. Municipal solid waste results were inconclusive.; Whole compost, nonextractable matter, humic acid and fulvic acid fractions of the compost were investigated by PY-GC/MS. PY-GC/MS in this research characterized the fractions in terms of the relative percentages of proteins, polysaccharides, aminosugars and polyhydroxyaromatic compounds they contained. Polysaccharides decreased noticeably. There was also a relative increase in proteins, aminosugar and polyhydroxyaromatic compounds. In addition, a new method of PY-CG/MS was developed. This enabled true quantification of individual pyrolysis fragments. This analysis showed, that only a small percentage of pyrolysis fragments are identified. It also, showed that the dominant peak was carton dioxide.; Overall, this research established a reference compost material in the synthetic compost. It also established a now method of PY-GC/MS that enables quantification or pyrolysis fragments. Finally, it characterized both a synthetic compost and a municipal solid waste compost and their humic fractions. Synthetic compost underwent more humification. Municipal solid waste compost underwent more degradation. (Abstract shortened by UMI.)