Patent ID: 7828976
Filing Date: 2010-11-09
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 phosphorous from the wastewater, forming iron or aluminum adsorption material having phosphorous adsorption sites thereon; clarifying the wastewater and producing a sludge having the iron or aluminum adsorption material therein; concentrating the iron or aluminum adsorption material in the wastewater by continuously recycling a substantial portion of the sludge having the iron or aluminum adsorption material therein and mixing the recycled sludge with the wastewater being treated; removing phosphorous from the wastewater by absorbing phosphorous onto the concentrated iron or aluminum adsorption material in the wastewater; and selecting a sludge recycle rate, determining the phosphorous concentration in a clarified effluent, and adjusting the sludge recycle rate until the phosphorus concentration in the clarified effluent is 0.05 mg/l or less.