Degradation of Biomacromolecules during High‐Rate Composting of Wheat Straw–Amended Feces

Abstract

Pig (Sus scrofa) feces, separately collected and amended with wheat straw, was composted in a tunnel reactor connected with a cooler. The composting process was monitored for 4 wk and the degradation of organic matter was studied by two chemical extraction methods, 13C cross polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) and pyrolysis gas chromatography-mass spectrometry (GC-MS). Wet-chemical extraction methods were not adequate to study the degradation of specific organic compounds as the extraction reagents did not give selective separation of hemicellulose, cellulose, proteins, and lignins. A new method was proposed to calculate the contribution of four biomacromolecules (aliphatics, proteins, polysaccharides, and lignin) from the 13C CPMAS NMR spectrum. Pyrolysis GC-MS allowed identification of the composition of the biomacromolecules. The biomacromolecules showed different rates of degradation during composting. High initial degradation rates of aliphatics, hemicellulose, and proteins were observed, where aliphatics were completely degraded and hemicellulose and proteins were partly recalcitrant during the four weeks of composting. The degradation rate of cellulose was much lower and degradation was not completed within the four weeks of composting. Lignin was not degraded during the thermophilic stage of composting but started to degrade slowly during the mesophilic stage. A combination of 13C CPMAS NMR and pyrolysis GC-MS gave good qualitative and semiquantitative assessments of the degradation of biomacromolecules during composting.

Isolation and screening of potential actinobacteria for rapid composting of rice straw

“…Carbon content is lost during composting in the form of CO 2 as metabolic end-product while total nitrogen content increase due to anabolism of cell structure, enzymes, hormones, etc. The increase of total nitrogen content during composting was in the agreement with other studies (Veeken et al 2001;Lee et al 2002) where they showed that straw with sludge amendment increased inorganic nitrogen content to soil. As a consequence, the C/N ratio decreased during the composting period.…”

A comparison of analytical techniques for evaluating food waste degradation by anaerobic digestion

“…Signals around 72-74 ppm were due to C2, C3 and C5 of cellulose as well as carbons from xylans [52]. The peak at 65 ppm may be assigned to crystalline components of C6 in hexose or C5 in pentose [53,54]. Carbohydrate structures have been reported to remain almost intact in humic and fulvic acids [50].…”

Characterization of different decomposition stages of biowaste using FT-IR spectroscopy and pyrolysis-field ionization mass spectrometry

“…Furthermore, Py-FIMS was used for characterizing four phases of cow manure composting (van Bochove et al 1996). Veeken et al (2001) investigated the evolution of macromolecules in a composting process of wheat straw and pig manure using pyrolysis gas chromatography-mass spectrometry.…”