The invention relates to treatment of microorganisms from an activated sludge process operating with enhanced biological phosphorus removal in a reactor with baffles or other devices to induce similar plug-flow effort, designed to optimally release phosphorus and/or magnesium from the microorganisms with or without chemical addition. Further, the disclosure relates to a process designed to produce both a lower solids, phosphorus and magnesium enriched liquid stream and a higher solids, phosphorus and magnesium enriched stream. The reactor operates to give optimal performance by operating in a plug-flow mode.