Ceramic filter and method for purifying water

Abstract

A ceramic filter is provided including a substrate, a separation layer comprising titania and having an average pore size in a range of 0.08 to 1 μm and a thickness in a range of 5 to 20 μm, and an intermediate layer formed between the substrate and the separation layer. The intermediate layer includes aggregate particles that are bonded together with glass frits, and aggregate particles of the intermediate layer are smaller than aggregate particles of the substrate and larger than aggregate particles of the separation layer.

1 . A ceramic filter, comprising: 
 a substrate;    a separation layer comprising titania and having an average pore size in a range of 0.08 to 1 μm and a thickness in a range of 5 to 20 μm; and    an intermediate layer formed between said substrate and said separation layer, said intermediate layer comprising aggregate particles bonded together with glass frits, said aggregate particles of said intermediate layer being smaller than an average pore size of said substrate and larger than aggregate particles of said separation layer.    
   
   
       2 . The ceramic filter according to  claim 1 , wherein said glass frits have an average particle size, in terms of volume definition, that is equal to or smaller than ⅔ of the average particle size of said aggregate particles of said intermediate layer and contain 10% by volume or less of particles having a size that is equal to or larger than 3/2 of the average particle size of said aggregate particles of said intermediate layer.  
   
   
       3 . A method for purifying raw water, comprising the steps of: 
 providing a ceramic filter comprising a substrate, a separation layer comprising titania and having an average pore size in a range of 0.08 to 1 μm and a thickness in a range of 5 to 20 μm, and an intermediate layer formed between said substrate and said separation layer, said intermediate layer comprising aggregate particles bonded together with glass frits, wherein said aggregate particles of said intermediate layer are smaller than an average pore size of said substrate and larger than aggregate particles of said separation layer; and    passing raw water through said ceramic filter.    
   
   
       4 . The method according to  claim 3 , further comprising a step of adding a coagulant to said raw water to cause partial or complete coagulation of impurities in said raw water before said raw water is passed through said ceramic filter; and 
 wherein said glass frits have an average particle size, in terms of volume definition, that is equal to or smaller than ⅔ of the average particle size of said aggregate particles of said intermediate layer and contain 10% by volume or less of particles having a size that is equal to or larger than 3/2 of the average particle size of said aggregate particles of said intermediate layer.    
   
   
       5 . The method according to  claim 3 , wherein said raw water is passed through said ceramic filter in a dead-end filtration manner.  
   
   
       6 . The method according to  claim 4 , wherein said raw water is passed through said ceramic filter in a dead-end filtration manner.