Patent ID: 8147695
Filing Date: 2012-04-03
Classification: C02F,Y02W,Y10S

Abstract:
1. A method of removing phosphorous from wastewater comprising: adding an iron or aluminum salt to the wastewater; removing phosphorous from the wastewater by precipitating phosphorous as ferric hydroxyphosphate or aluminum hydroxyphosphate; in addition to precipitating ferric hydroxyphosphate or aluminum hydroxyphosphate from the wastewater, precipitating iron or aluminum phosphorus adsorption species having phosphorous adsorption sites thereon; clarifying the wastewater and producing a clarified effluent and sludge having the iron or aluminum phosphorus adsorption species therein; concentrating the iron or aluminum phosphorus adsorption species in the wastewater by recycling portions of the sludge having the iron or aluminum phosphorus adsorption species therein and mixing the recycled sludge with the wastewater being treated; removing phosphorous from the wastewater by adsorbing phosphorous onto the concentrated iron or aluminum phosphorus adsorption species in the wastewater; monitoring a phosphorus concentration in the clarified effluent; and adjusting a sludge recycle rate to concentrate the iron or aluminum phosphorous adsorption species in the wastewater such that the clarified effluent includes a phosphorous concentration of 0.05 mg/L or less.