Major extractable organic compounds in the biologically degradable fraction of fresh, composted and anaerobically digested household waste

The recirculation of plant nutrients from urban areas to agriculture and ho rticulture and a need to reduce waste disposal by landfilling and incinerat ion are the main reasons for recycling the biologically degradable fraction of household waste. However, before using the recycled material in agricul tural and horticultural production it is necessary to make sure that the ma terial does not contain any unwanted contaminants. In general, there is a l ack of knowledge about organic contaminants in the degradable fraction of h ousehold waste and its compost and anaerobic digestion products. As a first step in a study of organic contaminants in household waste, and as part of the characterization of the degradation processes during composting and an aerobic digestion, the major extractable organic compounds were identified in the biologically degradable fraction of fresh, composted and anaerobical ly digested household waste. The organic compounds were isolated by supercr itical fluid extraction using carbon dioxide as extraction medium. Gas chro matography-mass spectrometry was used for qualitative analyses. Natural pro ducts, such as fatty acids, fatty acid esters, n-alkanes, aliphatic alcohol s, monoterpenes and triterpenes constituted the major organic components in the waste samples. In addition bis-(2-ethylhexyl) phthalate. frequently us ed as a plasticizer in polymers. was found in the extracts. In the chromato grams of the extracts of the Fresh and composted household waste, fatty aci ds and fatty acid esters dominated with respect to peak heights and the num ber of peaks identified. In the anaerobically digested household waste n-al kanes were the dominating compound class. The pattern of the n-alkanes, als o found in the fresh waste, possibly indicates a petrogenic origin of these compounds, perhaps caused by contamination during the collection of the ho usehold waste.