Excellence in Excrements: Upcycling of Herbivore Manure into Nanocellulose and Biogas

Funding Information: The authors acknowledge Tiergarten Schönbrunn for providing the elephant manure, Johannes Theiner from the Microanalytical Laboratory (Faculty of Chemistry) at the University of Vienna for performing elemental analysis and IR-spectroscopy, and the following students for their help with various aspects of the work: Alexander Blocher, Lisa Panzenböck, Hanna Hirn, Nina Troppmaier, Manuel Holzman (all University of Vienna), and Elodie Schaffner (Institut National Polytechnique de Toulouse). The authors also thank Stephan Puchegger from the Faculty Center for Nano Structure Research for his help with the SEM and Antje Potthast (Institute of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna) for measuring the molecular weight of the cellulose. This work was supported by OeAD (WTZ ZA 03/2017) enabling the collaboration with CSIR, Port Elisabeth, South Africa. K.W. is grateful for the financial support provided by the Institute of Materials Chemistry of University of Vienna (371300). E.K. acknowledges the support by FinnCERES Materials Bioeconomy Ecosystem. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society.The demand for animal products has significantly increased over the past decades as a result of the growing population and the heightened standards of living. Increased livestock farming does not only yield desired products but also significant quantities of wastes, particularly manure whose storage and application are being monitored with a tightening network of regulations. The problem is that manure is considered merely as a substrate for biogas production or as a fertilizer, whereas the substantial portion of fibers residing in herbivore manure has remained underutilized. Here, we propose a manure management system, in which not only biogas and fertilizer precursors but also high-value materials in the form of (nano)cellulose are produced. We show that high biogas yields can be achieved for elephant manure and the remaining substrate enables effortless isolation of cellulose nanofibers, leading to a significant reduction of the environmental impact compared with traditional systems based on wood.Peer reviewe