Simultaneous anoxic biological phosphorus and nitrogen removal

摘要

Methods and systems are provided for treating wastewater to simultaneously remove nitrogen, carbon, and phosphorus. The process includes an anoxic tank that receives at least two streams, including plant influent wastewater and return activated sludge. These streams are mixed in the anoxic tank to promote phosphorus release and fermentation of particulate and dissolved organic matter. The mixed liquor is transferred to an aerated tank having low dissolved oxygen concentrations to promote development of phosphorus-release bacteria that is eventually recycled to the anoxic tank by way of the return activated sludge. Simultaneous nitrification, denitrification, and phosphorus release occur in the aerated tank. A membrane tank separates treated effluent from activated sludge in a membrane tank.

主权项

1. A process for treating wastewater to simultaneously remove organic matter, nitrogen, and phosphorus, the process comprising:
providing two or more streams in a first tank operating under anoxic conditions, the two or more streams including plant influent wastewater and return activated sludge; mixing the plant influent wastewater and the return activated sludge in the first tank having a continuous oxygen deficit to form a mixed liquor to initiate phosphorus release and fermentation of particulate organic matter and dissolved organic matter; transferring the mixed liquor to a second tank; treating the mixed liquor in the second tank with operating a concentration of dissolved oxygen of less than 1.0 mg/l under microaerophilic conditions to simultaneously effectuate nitrification, denitrification, phosphorous release, and phosphorus uptake in the second tank; and transferring the mixed liquor to a third tank that separates treated effluent from activated sludge containing microorganisms, wherein a first portion of the activated sludge is returned to the first tank as the return activated sludge.