Humificación

i n d u s t r i a l c r o p s a n d p r o d u c t s 2 7 ( 2 0 0 8 ) 196–201

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Co-composting of lignin to build up humic substances—Strategies in waste management to improve compost quality
E. Smidt a,∗ , K. Meissl a , M. Schmutzer c , B. Hinterstoisser b
a

Institute of Waste Management, Muthgasse 107,1190 Vienna, Austria Institute of Wood Science and Technology, Peter Jordanstraße 82, 1190 Vienna, BOKU – University of Natural Resources and Applied Life Sciences, Vienna, Austria c Institute of Chemical Engineering, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
b

a r t i c l e
Keywords: Co-composting Lignin addition Humification

i n f o

a b s t r a c tCo-composting of different lignin sources with biogenic waste from the separate collection in Vienna was carried out in lab-scale experiments to promote humification as lignin is known to be a precursor molecule of humic substances. Humification is a target to be reached by composting due to the favorable properties for soils and plants. Extractable humic acids have been proved to be a suitable parameterto assess humification. Biogenic waste was used as a reference and basic material for co-composting of lignin. Lignin from different origins and composition was added: microbiologically degraded wood and lignin powder from industrial processes. Preliminary results show that addition of 2–5% of lignin powder could improve humic acid formation. Microbiologically degraded wood did not effect higherhumic acid contents within the short time of lab-scale composting. Humic acid determination is based on photometrical investigations. To ensure that humic acid contents were not pretended by the presence of lignin, quality control was carried out using FT-IR spectroscopy and thermal analysis. The results obtained showed that lignin had been integrated in the humic acid molecule. © 2007 Elsevier B.V.All rights reserved.

1.

Introduction

Approximately, 478,000 tonnes/year of biogenic waste materials comprising yard and kitchen waste (no leftovers) are collected separately in Austria. About 90,000 tonnes/year are processed in the City of Vienna. Due to the efficient separation and strict standards high quality input material for composting can be achieved (Plahl et al., 2002). Thebiological aerobic treatment is a usual method to process organic waste materials to get composts for different purposes. Organic matter recycling becomes more important with respect to

resource management. During composting humic substances are built up. Humic substances, especially humic acids, represent a stable fraction of compost organic matter. They are only synthesized in biologicalprocesses. Mechanisms are not completely elucidated and no stoichiometric formula of the humic acid molecule is available. Composting can be considered a humification technology. Humic substances are known to be advantageous for soils to maintain aggregate stability and therefore to prevent soil erosion. Water and nutrient holding capacity and availability depend significantly on this stable organic matterfraction. Due to the dark color they have a

Corresponding author. Tel.: +43 1 318 99 00 343; fax: +43 1 318 99 00 350. E-mail address: ena.smidt@boku.ac.at (E. Smidt). 0926-6690/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2007.07.007

∗

i n d u s t r i a l c r o p s a n d p r o d u c t s 2 7 ( 2 0 0 8 ) 196–201

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regulating effect on soiltemperature. Their contribution to plant health is an issue of interest although mechanisms are not clear yet. Humification contributes to carbon sequestration, contrary to the higher CO2 released by mineralization. In the context of global warming this environmental benefit has to be emphasized. Many studies have been done to shed light on the nature, chemical and physical properties of humic...