COMPOSTING PROCESS FOR THE STABILIZATION OF AN INDUSTRIAL FERMENTATION BIOMASS BYPRODUCT

摘要

Industrial fermentations are widely used in the manufacture of food-grade enzymes and other value-added products. A major stream of byproduct from these fermentations is biomass, containing unused substrate, dead bacterial and fungal biomass, and residual enzymes. Current methods of disposal of this byproduct are by lime stabilization and land application. The composting process was evaluated as a value-added alternative to current disposal practices. Specifically, the biomass was blended with laboratory animal bedding, furniture sawdust containing urea-formaldehyde (UF) resin, or a combination of these amendments and evaluated in a 3 treatments × 3 replicates pilot-scale experiment. The amendments were chosen for their ease of availability within the fermentation industry in the southeastern U.S. The process parameters monitored were temperature, moisture content, total and volatile solids losses, final compost quality, and breakdown of UF in the sawdust-amended treatments. Total solids reductions ranging from 22.0% to 44.1% were observed. Presence of high levels of nitrate-nitrogen (1.9 to 2.4 mg g -1 ) in treatments containing furniture sawdust were observed after 45 days of composting along with 17% to 20% reduction in UF concentrations, suggesting biodegradation of the resin. The compost in each treatment was completely stabilized, as measured by oxygen respirometric indices of 0.042 to 0.221 mg g -1 h -1