Characterization of Waste Organic Matter by FT-IR Spectroscopy: Application in Waste Science

A series of experiments has shown that FT-IR (Fourier transform infrared) spectroscopy is a helpful tool for characterizing waste organic matter, its decomposition, and stabilization in rotting processes. A specific set of differently treated input materials, originating from various composting plants, was chosen to reflect a wide range of spectroscopic properties. The approach to FT-IR spectra interpretation is presented. Changes of relative absorbances of the band at 2925 cm−1 (methylene groups of aliphatics) reflect the progress and dynamics of composting processes. Different processes can be compared by the specific development of their 2925 cm−1 band. Nitrate was quantified by calibrating nitrate band heights with added amounts of KNO3. The concentrations and band heights (absorbances) were linearly correlated (R2 = 0.9968, SD = 0.001). Bands of inorganic components are useful to assess the decomposition process because they also indicate the development of organic matter. Different wastes can be distinguished by their fingerprint region (1500–900 cm−1). This region also reveals fresh and undecomposed materials. The presence or absence of specific bands provides information about the decomposition status of materials.