Office of Solid Waste Management Programs “Co-Disposal” for Solid Wastes and Sewage Sludge

Each day, 15,000 tons of sludge solids are removed from U.S. wastewater treatment plants. A combination of events has caused disposal of this sludge to build up to a major problem for an increasing number of communities. Municipal sanitary wastewater contains about 0.35 pounds of dry solids per person per day. Added to this load are various commercial and industrial wastes. Ever-greater quantities of sludge are being produced as a result of increasing construction of wastewater treatment plants-and the fact that advanced wastewater plants produce more sludge than their predecessors. In addition to presenting more and more sludge solids for disposal each year, wastewater treatment plants are energy-intensive. The more complex and advanced the plant, the more energy it consumes. The current problems of energy-intensive industries need not be explained. Many conventional sludge disposal practices are becoming less available to municipalities. Spreading solid sludge on the land, and landfilling, are hampered by the lack of suitable sites. Ocean dumping is being phased out. Incineration has become unattractive because of its energy-intensive nature.