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要旨

The ability to quantify lignin is an important tool for characterizing the extent of decomposition of municipal solid waste (MSW). Traditionally, acid insoluble Klason lignin (KL) has been used to measure lignin. However, synthetic organic materials such as plastics and rubber present in MSW interfere with the traditional KL method, resulting in artificially high measurements. Another method for lignin analysis is CuO oxidation, in which lignin is oxidatively hydrolyzed into phenolic monomers that are quantified by high-performance liquid chromatography or gas chromatography–mass spectrography. The objective of this study was to evaluate the applicability of CuO oxidation to measure the lignin content of MSW. The study demonstrated that analysis of lignin monomers can be simplified by skipping the ethyl acetate extraction step and that ball milling is not necessary to optimize CuO oxidation. Neither the MSW components (e.g., plastics and metals) nor extractives affected CuO oxidation. The ratio of cellulose (Cel) plus hemicellulose (H) to KL [(Cel+H)/KL] has traditionally been used as an indicator of the extent of MSW decomposition. The use of Cel plus H to the sum of CuO oxidation products of lignin (Λ8) [(Cel+H)/Λ8] exhibited a similar trend to the traditional metric. CuO analysis provided information on the presence of hardwood, softwood, and nonwoody material in buried MSW, but is not recommended as a substitute for KL analysis.