Impact Assessment of the B.E.S.T. Thermal Sludge Drying Process in the Pulp and Paper Industry. Draft Final Report

摘要

The Basic Extractive Sludge Treatment (B.E.S.T.) drying process is being examined as an energy-saving alternative to flash drying of partially dewatered sludge produced by wastewater treatment in the pulp and paper industry. The B.E.S.T. process relies on the low 133 Btu/lb heat of vaporization of the solvent triethylamine (TEA), and on the action of TEA as a sludge conditioning agent in mechanical dewatering, to produce almost completely dry solids from input sludges of 6 to 30% solids. The dried solids may be sold as fertilizer (e.g., 7% Nitrogen, 3% P sub 2 O sub 5 ) or burned to raise steam (e.g., 9500 Btu/lb volatiles, 20% ash). In this study, costs and energy usage were developed for sludge disposal process trajectories used or potentially used in the pulp and paper industry. Evaluations were performed on trajectories, or series of processes, in order to establish common grounds for comparisons, such as similar starting and finishing points in sludge treatment. The amount of sludge of the type which might require a thermal drying process was projected through the end of the century. Costs and energy usage for complete disposal process trajectories were compared assuming 100% saturation of the estimated market. A preliminary toxicity analysis was performed on the TEA solvent used in the B.E.S.T. process. (ERA citation 08:055916)