Sludge treatment and disposal problems and costs grow with increased concern about the quality of wastewater treatment. As standards for effluent quality in the United States have become stricter, the problems of sludge treatment and disposal have grown disproportionately. Today the costs of sludge treatment and disposal at a modern metropolitan sewage treatment plant represent almost half the cost of wastewater treatment. Sludge problems, although of serious concern everywhere, are different for different locations. The approach to sludge handling and the solution to problems depends on geography, climate, population, proportion and nature of industrial wastes in the wastewater, and local details (e.g., proximity of hills, rivers, residences, farmland, landfills, strip-mined land). The report scans U.S. practice and identifies the predominant and more successful approaches to sludge treatment and disposal that have developed over the years.