Chemical treatment of wastes, despite early interest in such methods, fell into disfavor as improved biological methods were developed. Biological treatment is far superior to chemical treatment for the removal of soluble organic matter. However, in recent years there has been a revived interest in special applications of chemical methods, especially for processing biologically treated effluents when additional purification is needed. This research was undertaken to investigate to what extent chemical flocculation methods can complement, and partially substitute for, the biological treatment process.