PROCESS TO ENHANCE PHOSPHORUS REMOVAL FOR ACTIVATED SLUDGE WASTEWATER TREATMENT SYSTEMS

摘要

Contaminated wastewaters comprising biochemical oxygen demand (BOD), nitrogen and phosphorus are treated by an activated sludge process. The process utilizes an activated sludge tank, a solid-liquid separator, and a bioreactor to significantly reduce, or eliminate, waste activated sludge (WAS) within a sludge stream. A sidestream reactor is employed downstream from the bioreactor to remove soluble phosphates left in the sludge stream by the low WAS process. Within the sidestream reactor, a source of multivalent metal ions is added to a slightly alkaline sludge stream to precipitate the phosphates. The solid phosphates have a specific gravity higher than that of the organic matter in the sludge stream and may be separated from the sludge stream based upon differential settling velocity.