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Hydrolysis rates, methane production and nitrogen solubilisation of grey waste components during anaerobic degradation

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)501-508
Number of pages8
JournalBioresource Technology
Issue number4
Publication statusPublished - Mar 2005
Externally publishedYes
Publication typeA1 Journal article-refereed


Municipal grey waste (i.e. the remaining fraction in municipal waste management systems in which putrescibles (biowaste) and other recyclables (paper, metals, glass) are source-segregated) was manually sorted into six main fractions on the basis of composition and also separated by sieving (100 mm mesh size) into two fractions, oversized and undersized, respectively. In practice, in waste management plant the oversized fraction is (or will be) used to produce refuse-derived fuel and the undersized landfilled after biological stabilisation. The methane yields and nitrogen solubilisation of the grey waste and the different fractions (all studied samples were first milled to 5 mm particle samples) were determined in a 237-day methane production batch assay and in a water elution test, respectively. The grey waste was found to contained remnants of putrescibles and also a high amount of other biodegradable waste, including packaging, cartons and cardboard, newsprint, textiles and diapers. These waste fractions comprised 41%-w/w of the grey waste and produced 40-210 m3 methane (total solids (TS))-1 and less than 0.01 gNH4-NkgTS-1 added except diapers which produced 9.8 gNH4-N kgTS-1 added in the batch assays. In the case of the two sieved fractions and on mass bases, most of the methane originated from the oversized fraction, whereas most of the NH4-N was solublised from the undersized fraction. The first-order kinetic model described rather well the degradation of each grey waste fraction and component, showing the different components to be in the range 0.021-0.058 d-1, which was around one-sixth of the values reported for the source-segregated putrescible fraction of MSW.


  • Anaerobic degradation, Components, Grey waste, Hydrolysis rate, Landfill, Methane, Municipal solid waste, Nitrogen, Solubilisation, Source-segregation