COMPOSTING PROCESS FOR THE STABILIZATION OF AN INDUSTRIAL FERMENTATION BIOMASS BYPRODUCT

Abstract

Industrial fermentations are widely used in the manufacture of foodgrade enzymes and other valueaddedproducts. A major stream of byproduct from these fermentations is biomass, containing unused substrate, dead bacterial andfungal biomass, and residual enzymes. Current methods of disposal of this byproduct are by lime stabilization and landapplication. The composting process was evaluated as a valueadded alternative to current disposal practices. Specifically,the biomass was blended with laboratory animal bedding, furniture sawdust containing ureaformaldehyde (UF) resin, ora combination of these amendments and evaluated in a 3 treatments 3 replicates pilotscale experiment. The amendmentswere chosen for their ease of availability within the fermentation industry in the southeastern U.S. The process parametersmonitored were temperature, moisture content, total and volatile solids losses, final compost quality, and breakdown of UFin the sawdustamended treatments. Total solids reductions ranging from 22.0% to 44.1% were observed. Presence of highlevels of nitratenitrogen (1.9 to 2.4 mg g1) in treatments containing furniture sawdust were observed after 45 days ofcomposting along with 17% to 20% reduction in UF concentrations, suggesting biodegradation of the resin. The compost ineach treatment was completely stabilized, as measured by oxygen respirometric indices of 0.042 to 0.221 mg g1 h1.