title: Co-composting of biowaste and wood ash, influence on a microbially driven-process.
abstract: A trial at semi-industrial scale was conducted to evaluate the effect of wood ash amendment on communal biowaste in a composting process and on the final composts produced. For this purpose, three treatments including an unamended control (C0) and composts with additions of 6% (C6), and 12% (C12) of wood ash (w/w) were studied, and physico-chemical parameters as well as microbial activity and community composition were investigated. At the end of the process, composts were tested for toxicity and quality, and microbial physiological activity. The influence of ash addition on compost temperature, pH, microbial activity and composition was stronger during the early composting stages and diminished with time, whereby composts became more similar. Using the COMPOCHIP microarray, a reduction in the pathogenic genera Listeria and Clostridium was observed, which together with the temperature increases of the composting process helped in the hygienisation of composts. Lactobacillus species were also affected, such that reduced hybridisation signals were observed with increased ash addition, due to the increased pH values in amended composts. Organic matter mineralisation was also increased through ash addition, and no negative effects on the composting process were observed. The nutrient content of the final products was increased through the addition of ash, and no toxic effects were observed. Nonetheless, greater concentrations of heavy metals were found in composts amended with more ash, which resulted in a downgrading of the compost quality according to the Austrian Compost Ordinance. Thus, regulation of both input materials and end-product quality is essential in optimising composting processes.
authors.affiliation: Universität Innsbruck, Institut für Mikrobiologie, Technikerstraße 25d, A-6020 Innsbruck, Austria. Electronic address: marina.fernandez@uibk.ac.at.
authors.forename: Marina
authors.initials: M
authors.lastname: Fernández-Delgado Juárez
authors.affiliation: Universität Innsbruck, Institut für Mikrobiologie, Technikerstraße 25d, A-6020 Innsbruck, Austria; Universität Zürich, Institut für Veterinärpathologie, Winterthurerstraße 268, CH-8057 Zürich, Switzerland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Prähauser
authors.affiliation: Universität Innsbruck, Institut für Mikrobiologie, Technikerstraße 25d, A-6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Walter
authors.affiliation: Universität Innsbruck, Institut für Mikrobiologie, Technikerstraße 25d, A-6020 Innsbruck, Austria.
authors.forename: Heribert
authors.initials: H
authors.lastname: Insam
authors.affiliation: Universität Innsbruck, Institut für Mikrobiologie, Technikerstraße 25d, A-6020 Innsbruck, Austria.
authors.forename: Ingrid H
authors.initials: IH
authors.lastname: Franke-Whittle
mesh_terms: D001317:Austria; D001419:Bacteria / Q000378:metabolism*; D059027:Recycling / Q000379:methods*; D012037:Refuse Disposal; D012988:Soil Microbiology; D018505:Waste Management / Q000379:methods*; D014934:Wood / Q000737:chemistry*
keywords: Compost; Compost maturity; DGGE; Heavy metal content; Sanitation; Waste valorisation