This investigation was undertaken to demonstrate the application of the anaerobic filter in the treatment of liquor waste resulting from heat treatment of raw sludge in municipal sewage treatment plants. The liquor which contains high concentrations of soluble wastes is often returned to the heat end of a plant, where it can impose an additional load on the plant's operation and reduce its efficiency. Two pilot anaerobic filter columns were operated over a period of 18 months at the Muddy Creek Plant of the Metropolitan Sewer District of Greater Cincinnati. Operational data demonstrated high levels of BOD and COD removals from the raw heat treatment liquor. The generated gas contained 65 to 70 percent methane. Based on the pilot column studies, a suggested design and costs for an anaerobic filter unit were developed. These costs were compared to costs of other means of treatment such as the aerobic alternative. The anaerobic filter process had lower capital and operating costs than other modes of treatment. The gas produced was calculated to provide fuel to maintain the temperature of the filter at 35C, and provide additional capacity for other plant uses. These calculations show a net profit in operating costs. Further investigations to optimize design configurations are suggested.