Title: Co-composting of seaweed with lignocellulosic substratum: effect of the compost composition on compost humic substances

Authors: Oskars Bikovens; Sarmite Janceva; Laima Vevere; Ingrida Purina; Galina Telysheva

Addresses: Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, Latvia ' Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, Latvia ' Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, Latvia ' Latvian Institute of Aquatic Ecology, Voleru Street 4, Riga, Latvia ' Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga, Latvia

Abstract: Seaweed is one of Latvia's underexploited natural resources. Green and brown algae collected after stranding on beaches were co-composted with lignocellulosic substratum - grass and/or hardwood sawdust. Six different compost compositions were prepared. Composting was carried out indoors in the autumn-winter season. The correspondence of the obtained composts to the national and EU legislation was evaluated. The best results were obtained for compost prepared from green algae, grass and sawdust mixture. Compost raw material, compost and compost humic acids were characterised by elemental analysis, UV and Fourier transform infrared spectroscopy and monosaccharides analyses. The compost humic substance composition was found to be dependent on the compost raw materials. Compost humic acids constituted of recognisable algae and plants biomolecules structures, including lignin-derived structures and carbohydrates. Humic acids of the obtained compost contained around 8% monosaccharides. Fucose is a deoxy sugar typical for algae and not for higher plants, and can be used as a chemical indicator of algae biomass in compost.

Keywords: algae; compost; humic acids; fucose; waste management.

DOI: 10.1504/IJARGE.2020.115327

International Journal of Agricultural Resources, Governance and Ecology, 2020 Vol.16 No.3/4, pp.263 - 277

Received: 06 Sep 2019
Accepted: 15 Sep 2020
Published online: 28 May 2021 *

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