simultaneous anoxic biological removal of phosphorus and nitrogen with energy recovery

摘要

Simultaneous anoxic biological removal of phosphorus and nitrogen with energy recovery. The present invention relates to methods and systems for treating wastewater to simultaneously remove nitrogen, carbon and phosphorus while recovering energy in the form of methane and carbon dioxide. A stream containing ammonia is directed to a pretreatment tank that produces excess sludge, biogas, and pretreated stream. The pretreated stream has at least 45% less carbon than the ammonia-containing stream. The pretreated stream is then directed to an anoxic tank, which promotes phosphorus release and the fermentation of dissolved and particulate organic matter. The mixed liquor is transferred to an aerated tank having low dissolved oxygen concentrations to promote the development of phosphorus bacteria which are eventually recycled to the anoxic tank by the return of activated sludge. At the same time nitrification, denitrification and phosphorus release occur in the aerated tank. A membrane tank separates treated effluent from activated sludge into a membrane tank.