Abstract: A wastewater treatment system incorporates three interconnected, but separately controlled, processes to enhance biological phosphorus removal. The first process is a mainstream biological treatment process utilizing aerobic and solids separation zones and the provision of return activated sludge. The next is a first sidestream process for anoxic/anaerobic "selection" of desirable BPR organisms. Finally, a second sidestream process serves to ferment organic material in some of the return activated sludge to produce food utilized in the first sidestream selection process. The system permits the three processes to be separated from each other by creating two sidestreams, allowing all three processes to be controlled separately and optimized in satisfying their own specific goals.