PubMed · 4134447
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H Trowell. 1974-07-06. Letter: Bran hypothesis.. https://doi.org/10.1016/s0140-6736(74)91394-4
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Cellulosic textiles, constituting over 30% of global fibre production, are biodegradable but remain challenging to recycle at scale owing to their high crystallinity, chemical finishes, and heterogeneous waste streams. Although microorganisms drive cellulose turnover in natural ecosystems, their potential for transforming anthropogenic cellulosic waste remains largely unexplored. In this study, composting was evaluated both as a sustainable approach to textile biodegradation and a reservoir of cellulolytic microorganisms with biotechnological potential. Biodegradation assays of cotton and lyocell were integrated with shotgun metagenomics and targeted cultivation to identify microbial taxa and enzymes involved in cellulose degradation. Composting trials showed that degradation was strongly influenced by both composting system and fibre composition. Community composting achieved near-complete textile disintegration, while shredded textiles exhibited the highest degradation rates, reaching up to 97%. Shotgun metagenomic revealed a bacterial-dominated community enriched in Actinomycetota and Bacillota and characterised by an abundance of glycoside hydrolases. Culture-based screening recovered 62 microbial isolates, of which Neurospora and Aspergillus exhibited the highest cellulolytic activity (>60%). In vitro assays further showed that cotton was more readily degraded than lyocell, with several isolates achieving >70% mass loss. Metagenomic approach revealed a predominantly bacterial composting community at the sampled stage, whereas cultivation preferentially recovered fungi that, despite their low relative abundance in situ, exhibited strong cellulolytic potential. These findings highlight the potential of composting as a sustainable end-of-life strategy for cellulosic textiles and identify compost microbiomes as valuable reservoirs of cellulolytic microorganisms for the development of sustainable bioprocesses for textile waste treatment.
In this paper, we present our study of the speciation of copper and hexavalent chromium sorbed onto a lignocellulosic substrate, using analytical microscopy. The lignocellulosic substrate constitutes a low-cost biomaterial that can be used in wastewater treatment. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) was used to determine the speciation of the two metal ions on the constitutive moieties of the lignocellulosic substrate. The use of a staining agent sensitive to carbon unsaturation allowed us to differentiate between the microstructures rich in lignin entities and those rich in cellulose entities. The EDX analysis showed that metal ions are preferentially sorbed onto microstructures rich in lignin moieties. The energy electron loss spectroscopy (EELS) was used to determine the oxidation states of chromium in association with lignocellulosic moieties. We showed that the sorption process of hexavalent chromium requires the reduction of Cr(VI) into Cr(III) and the probable oxidation of lignin moieties.
The effect of varying the compression pressure on the brittle fracture tendency of alpha-cellulose and lactose tablets has been investigated. Tablet tensile strength, (T), packing fraction, (Pf), and brittle fracture index (BFI) were determined at different compression pressures (0.82, 1.22 and 1.63 MPa). In another aspect of the study, alpha-cellulose and tapioca powders were mixed in various proportions to obtain powders of varying plastoelasticity. Their tableting characteristics T, Pf and BFI were also determined at the different compression pressures. The polymer, alpha-cellulose displayed the characteristics of plastic compression--a low BFI but high T and Pf values while lactose displayed the characteristics of elastic compression--a high BFI but low T and Pf values. The degree of plastic compression decreased as the proportion of tapioca in the powder mixture increased from 0 to 50% w/w. Higher concentrations of tapioca >50% produced crumbly tablets at all compression pressures, thus indicating that tapioca is highly elastic. Increase in the compression pressure caused an increase in the BFI values of lactose tablets, 0.39-0.76 but a decrease in the BFI values of alpha-cellulose tablets, 0.38-0.09. This decrease became less pronounced as the plasticity of the powder mixtures decreased. The difference in the response of the tablets to the change in compression pressure relates to the difference in the plastoelasticity of the materials tested.