title: Assessment of compost maturity by using an electronic nose.
abstract: The composting process produces and emits hundreds of different gases. Volatile organic compounds (VOCs) can provide information about progress of composting process. This paper is focused on the qualitative and quantitative relationships between compost age, as sign of compost maturity, electronic-nose (e-nose) patterns and composition of compost and composting gas at an industrial scale plant. Gas and compost samples were taken at different depths from composting windrows of different ages. Temperature, classical chemical parameters, O2, CO, combustible gases, VOCs and e-nose profiles were determined and related using principal component analysis (PCA). Factor analysis carried out to a data set including compost physical-chemical properties, pile pore gas composition and composting time led to few factors, each one grouping together standard composting parameters in an easy to understand way. PCA obtained from e-nose profiles allowed the classifying of piles, their aerobic-anaerobic condition, and a rough estimation of the composting time. That would allow for immediate and in-situ assessment of compost quality and maturity by using an on-line e-nose. The e-nose patterns required only 3-4 sensor signals to account for a great percentage (97-98%) of data variance. The achieved patterns both from compost (chemical analysis) and gas (e-nose analysis) samples are robust despite the high variability in feedstock characteristics (3 different materials), composting conditions and long composting time. GC-MS chromatograms supported the patterns.
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), P.O. Box 1052, 41080 Sevilla, Spain. Electronic address: rafael.lopez@csic.es.
authors.forename: Rafael
authors.initials: R
authors.lastname: López
authors.affiliation: Departamento de Química y Ciencia de los Materiales, Facultad de Ciencias Experimentales, Univ. de Huelva, Campus Universitario El Carmen, Avenida de las Fuerzas Armadas, 21071 Huelva, Spain. Electronic address: giraldez@uhu.es.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Giráldez
authors.affiliation: Departamento de Ingeniería Química, Química Física y Química Orgánica, Facultad de Ciencias Experimentales, Univ. de Huelva, Campus Universitario El Carmen, Avenida de las Fuerzas Armadas, 21071 Huelva, Spain. Electronic address: alberto.palma@diq.uhu.es.
authors.forename: Alberto
authors.initials: A
authors.lastname: Palma
authors.affiliation: Departamento de Ingeniería Química, Química Física y Química Orgánica, Facultad de Ciencias Experimentales, Univ. de Huelva, Campus Universitario El Carmen, Avenida de las Fuerzas Armadas, 21071 Huelva, Spain. Electronic address: dblanco@uhu.es.
authors.forename: M
authors.initials: M
authors.lastname: Jesús Díaz
mesh_terms: D062609:Electronic Nose; D005163:Factor Analysis, Statistical; D005740:Gases / Q000032:analysis; D012987:Soil / Q000737:chemistry; D013696:Temperature; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D005740:Gases; D012987:Soil; D055549:Volatile Organic Compounds
keywords: Biomass; Compost maturity; Composting; Green wastes; Manure; Pruning residues; VOCs