Method and apparatus for wastewater treatment

Abstract

Phosphorus in wastewater is removed by using an apparatus including a settling tank, an anaerobic tank, an aerobic tank, and a final settling tank. Nitrogen in wastewater is removed by using an apparatus including a settling tank, an anaerobic tank, a nitrification tank, and a final settling tank.

What is claimed is:  
     
         1 . A method for treating wastewater comprising the steps of: 
 removing phosphorus from wastewater, using a wastewater treatment apparatus comprising a settling tank, an anaerobic tank, and an aerobic tank;    crushing at least a portion of sediment in the settling tank; and    supplying the crushed sediment to the anaerobic tank.    
     
     
         2 . A method for treating wastewater according to  claim 1 , wherein the step of crushing comprises grinding a portion of the sediment in the settling tank.  
     
     
         3 . A wastewater treatment apparatus comprising: 
 a settling tank for removing solids contained in wastewater;    an anaerobic tank, wherein effluent from the settling tank is introduced and activated sludge releases phosphoric acid ion from cells into wastewater by a biological phosphorus-releasing reaction;    an aerobic tank, wherein effluent from the anaerobic tank is introduced and activated sludge takes up phosphoric acid ion into cells by a biological phosphorus-uptake reaction;    a line for withdrawing sediment from the settling tank;    a crushing device for crushing the withdrawn sediment; and    a line for supplying the crushed sediment to the anaerobic tank.    
     
     
         4 . A wastewater treatment apparatus according to  claim 3 , wherein the crushing device comprises a device for grinding the sediment.  
     
     
         5 . A method for treating wastewater comprising the steps of: 
 removing phosphorus from wastewater, using a wastewater treatment apparatus comprising a primary settling tank, an anaerobic tank, an aerobic tank, and a final settling tank;    returning effluent from the aerobic tank to the primary settling tank;    returning sludge withdrawn from the final settling tank to the primary settling tank; and    sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         6 . A method for treating wastewater according to  claim 5 , wherein the step of removing phosphorus comprises removing phosphorus from the wastewater, using a wastewater treatment apparatus comprising a primary settling tank, an anaerobic tank, an anoxic tank, an aerobic tank, and a final settling tank.  
     
     
         7 . A method for treating wastewater according to  claim 6 , further comprising the step of sending sludge in the primary settling tank to the anoxic tank.  
     
     
         8 . A method for treating wastewater comprising the steps of: 
 removing phosphorus from wastewater, using a wastewater treatment apparatus comprising a primary settling tank, an anaerobic tank, an aerobic tank, and a final settling tank;    returning effluent from the aerobic tank to the primary settling tank; and    sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         9 . A method for treating wastewater comprising the steps of: 
 removing phosphorus from wastewater, using a wastewater treatment apparatus comprising a primary settling tank, an anaerobic tank, an aerobic tank, and a final settling tank;    returning sludge withdrawn from the final settling tank to the primary settling tank; and    sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         10 . A wastewater treatment apparatus comprising: 
 a primary settling tank for removing solids contained in wastewater;    an anaerobic tank, wherein effluent from the primary settling tank is introduced and activated sludge releases phosphoric acid ion from cells into the wastewater by a biological phosphorus-releasing reaction;    an aerobic tank, wherein effluent from the anaerobic tank is introduced and activated sludge takes up phosphate anions into cells by a biological phosphorus-uptake reaction;    a final settling tank for settling the wastewater treated in the aerobic tank;    a line for returning effluent from the aerobic tank to the primary settling tank;    a line for returning sludge withdrawn from the final settling tank to the primary settling tank; and    a line for sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         11 . A wastewater treatment apparatus according to  claim 10 , further comprising an anoxic tank for denitrifying effluent from the anaerobic tank, the anoxic tank being disposed between the anaerobic tank and the aerobic tank.  
     
     
         12 . A wastewater treatment apparatus according to  claim 11 , further comprising a line for sending sludge in the primary settling tank to the anoxic tank.  
     
     
         13 . A wastewater treatment apparatus comprising: 
 a primary settling tank for removing solids contained in wastewater;    an anaerobic tank, wherein effluent from the primary settling tank is introduced and activated sludge releases phosphate anions from cells into the wastewater by a biological phosphorus-releasing reaction;    an aerobic tank, wherein effluent from the anaerobic tank is introduced and activated sludge takes up phosphate anions into cells by a biological phosphorus-uptake reaction;    a final settling tank for settling the wastewater treated in the aerobic tank;    a line for returning effluent from the aerobic tank to the primary settling tank; and    a line for sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         14 . A wastewater treatment apparatus comprising: 
 a primary settling tank for removing solids contained in wastewater;    an anaerobic tank, wherein effluent from the primary settling tank is introduced and activated sludge releases phosphate anions from cells into the wastewater by a biological phosphorus-releasing reaction;    an aerobic tank, wherein effluent from the anaerobic tank is introduced and activated sludge takes up phosphate anions into cells by a biological phosphorus-uptake reaction;    a final settling tank for settling the wastewater treated in the aerobic tank;    a line for returning sludge withdrawn from the final settling tank to the primary settling tank; and    a line for sending sludge withdrawn from the primary settling tank to the anaerobic tank or the aerobic tank.    
     
     
         15 . A method for treating wastewater comprising the steps of: 
 removing nitrogen from wastewater, using a wastewater treatment apparatus comprising a settling tank and a denitrification tank;    crushing at least a portion of sediment in the settling tank; and    supplying the crushed sediment to the denitrification tank.    
     
     
         16 . A method for treating wastewater according to  claim 15 , wherein the step of crushing comprises grinding a portion of the sediment in the settling tank.  
     
     
         17 . A method for treating wastewater comprising the steps of: 
 removing nitrogen from wastewater, using a wastewater treatment apparatus comprising a settling tank, an anaerobic tank, and a nitrification tank;    crushing at least a portion of sediment in the settling tank; and    supplying the crushed sediment to the anaerobic tank.    
     
     
         18 . A method for treating wastewater according to  claim 17 , wherein the step of crushing comprises grinding a portion of the sediment in the settling tank.  
     
     
         19 . A wastewater treatment apparatus comprising: 
 a settling tank for removing solids contained in wastewater;    a denitrification tank, wherein effluent from the settling tank is introduced and nitrate nitrogen or nitrite nitrogen in the wastewater is reduced to nitrogen gas;    a line for withdrawing sediment from the settling tank;    a crushing device for crushing the withdrawn sediment; and    a line for supplying the crushed sediment to the denitrification tank.    
     
     
         20 . A wastewater treatment apparatus according to  claim 19 , wherein the crushing device comprises a device for grinding the sediment.  
     
     
         21 . A wastewater treatment apparatus comprising: 
 a settling tank for removing solids contained in wastewater;    an anaerobic tank, wherein effluent from the settling tank is introduced, nitrate nitrogen or nitrite nitrogen in the wastewater is reduced to nitrogen gas, and activated sludge releases phosphate anions from cells into the wastewater by a biological phosphorus-releasing reaction;    a line for withdrawing sediment from the settling tank;    a crushing device for crushing the withdrawn sediment; and    a line for supplying the crushed sediment to a denitrification tank.    
     
     
         22 . A wastewater treatment apparatus according to  claim 21 , wherein the crushing device comprises a device for grinding the sediment.  
     
     
         23 . A wastewater treatment apparatus according to  claim 21 , further comprising a nitrification tank, wherein effluent from the anaerobic tank is introduced and nitrogen compounds in the wastewater are oxidized to nitrate nitrogen or nitrite nitrogen.  
     
     
         24 . A wastewater treatment apparatus comprising: 
 a primary settling tank for removing solids contained in wastewater;    a denitrification tank, wherein effluent from the primary settling tank is introduced, and nitrate nitrogen or nitrite nitrogen in the wastewater is reduced to nitrogen gas;    a nitrification tank, wherein effluent from the denitrification tank is introduced and nitrogen compounds in the wastewater are oxidized to nitrate nitrogen or nitrite nitrogen;    a final settling tank for settling effluent from the nitrification tank; and    a line for returning a portion of effluent from the nitrification tank or a portion of effluent from the final settling tank to the primary settling tank.    
     
     
         25 . A wastewater treatment apparatus according to  claim 24 , further comprising an anaerobic tank disposed between the primary settling tank and the denitrification tank, wherein effluent from the primary settling tank is introduced, nitrate nitrogen or nitrite nitrogen in the wastewater is reduced to nitrogen gas, and activated sludge releases phosphate anions from cells into wastewater by a biological phosphorus-releasing reaction.  
     
     
         26 . A wastewater treatment apparatus according to  claim 25 , further comprising a line for sending sediment in the primary settling tank to the anaerobic tank.  
     
     
         27 . A wastewater treatment apparatus according to  claim 24 , further comprising a line for sending sediment in the primary settling tank to the denitrification tank.