Composting and storage of organic household waste with different litter amendments. I: carbon turnover

Composting of source-separated organic household wastes is becoming a more common practice in several countries. Carbon decomposition dynamics during composting are important for an overall understanding of the process. We in vestigated over 590 days losses of organic C and decomposition of C constit uents in artificial organic household waste mixed with six different litter amendments; straw, leaves, hardwood, softwood, paper and sphagnum peat. Li tter addition was necessary to achieve an aerobic process. Samples were ana lysed for dry matter, ash, organic C, volatile fatty acids, and lignin, cel lulose and hemicellulose fractions. Calculated by first-order kinetics, res idual amounts of dry matter were 22-63% and of organic C 11-61%, and both a mounts were highest in the peat mixture and lowest in the control without l itter addition. Rate constants for dry matter and organic C decomposition w ere highest in the leaf mixture and lowest in the control. The initial lign in content in the mixtures was highly correlated (R-2 = 0.91) with the resi dual amount of organic C. A lag phase, of varying length, in lignin decompo sition was present in some but not all cases. Cellulose decomposition was s lower in leaf, hardwood and softwood mixtures than in paper and straw mixtu res. The results showed that the characteristics of litter amendments great ly influence the composting process. (C) 2000 Elsevier Science Ltd. All rig hts reserved.