Stability and quality of municipal solid waste compost from a landfill aerobic bioreduction process

Solid waste compost product from an aerobic bioreduction process at a full-scale landfill was characterized. The landfill was sampled after 5 months of aerobic bioreduction for spatial variations in biological stability. The product after 14 months of bioreduction was excavated and screened in three different ways to improve product quality. After 5 months of bioreduction, the stability index (SI) of solid waste in the landfill ranged from low activity (0.15-0.67 mg g(-1) h(-1)) in the 6.1-7.6-m depth layer to high activity (1.42-2.14 mg g(-1) h(-1)) at the 4.6-6.1-m depth layer. After 14 months of bioreduction, the 9.5-mm trommel screen provided a superior product among those tested and resulted in total inert content of 3.5% compared to 9.0% (dry basis) when using a 19.1-mm screen. Product SI ranged from 0.39 to 0.55 mg g(-1) h(-1), indicating stability. Regulated heavy metals were below EPA exceptional quality compost levels. Lead, nickel, chromium and zinc were at relatively higher levels than other metals. (C) 2002 Elsevier Science Ltd. All rights reserved.