The Los Angeles County Sanitation Districts conducted a 14-month pilot and plant scale sludge dewatering research program aimed at selecting a system to remove approximately 95 percent of the suspended solids contained in high rate anaerobically digested primary sludge. An existing dewatering system at the site of the research consisted of six horizontal scroll centrifuges. During the course of the study both digested sludge and centrate from the existing centrifuges were used as feed to the various dewatering systems investigated. Based on the results of the research, cost estimates for dewatering and ultimate disposal of 300 dry tons per day of wastewater solids were prepared.