Chemical-resistant bioreactor carrier, processes for producing the carrier and use of the carrier

Abstract

The present invention provide: a bioreactor carrier having a suitable water swelling property, a suitable degree of volumetric swelling and a suitable specific gravity as well as exhibiting high chemical resistance to be suitable for use in the microbial treatment of organic waste water having a high chemical content; processes for efficiently producing the bioreactor carrier; and use of the bioreactor carrier. More specifically, there are provided: a chemical-resistant bioreactor carrier comprising (A) a specific water-swellable thermoplastic resin and (B) a specific resin compatible with the water-swellable thermoplastic resin (A), and as the case may be, (C) an inorganic filler, characterized in that the degree of volumetric swelling of the carrier is controlled to within a range of 120 to 3,000% and that the specific gravity of the carrier on swelling in water is controlled to within a range of 0.98 to 2.12; processes for efficiently producing the chemical-resistant bioreactor carrier; and a denitrification process for organic waste water having a high chemical content, characterized in that the chemical-resistant bioreactor carrier is used as a microbe immobilization carrier in the microbial nitrification and denitrification of nitrogenous components in the organic waste water.

What is claimed is:  
     
         1 . A chemical-resistant bioreactor carrier, comprising: 
 (A) a water-swellable thermoplastic resin selected from the group consisting of: 
 (A1) a polyurethane resin prepared by the reaction of diphenylmethane diisocyanate and polyethylene glycol having a molecular weight of 3,000 to 12,000 with or without 1,4-butanediol;  
 (A2) a cross-linked N-vinylacetamide polymer or copolymer;  
 (A3) a nonionic polyalkyleneoxide-base thermoplastic resin; and  
 (A4) a cross-linked product of polyacrylic acid salt, and  
   (B) a resin compatible with the water-swellable thermoplastic resin component (A), selected from the group consisting of: 
 (B1) a polyether-based elastomer;  
 (B2) a polyester-based elastomer;  
 (B3) an ethylene-acrylic acid copolymer resin; and  
 (B4) an acid-modified polyethylene,  
   wherein the degree of volumetric swelling of said carrier is controlled to within the range of 120 to 3,000%.    
     
     
         2 . The chemical-resistant bioreactor according to  claim 1 , further comprising (C) an inorganic filler, 
 wherein the specific gravity of said carrier upon swelling in water is controlled to within the range of 0.98 to 2.12.    
     
     
         3 . The chemical-resistant bioreactor according to  claim 2 , wherein the inorganic filler (C) has an average particle size of 0.1 to 50 μm and a specific gravity of 1.5 or more.  
     
     
         4 . The chemical-resistant bioreactor carrier according to  claim 2 , wherein the inorganic filler (C) is contained in an amount of 1 to 350 parts by weight based on 100 parts by weight of the total amount of the resins (A) and (B).  
     
     
         5 . The chemical-resistant bioreactor carrier according to  claim 1 , wherein the weight ratio of the resin (A) to the resin (B) falls within the range of 90:10 to 10:90.  
     
     
         6 . A process for the production of a chemical-resistant bioreactor carrier having a degree of volumetric swelling controlled to within the range of 120 to 3,000%, the process comprising the steps of: 
 blending the water-swellable thermoplastic resin (A) as set forth in  claim 1  with the compatible resin (B) as set forth in  claim 1;     heat melting the resultant blend;    extruding the melted blend into the form of a strand by means of an extruder; and    continuously cutting the strand.    
     
     
         7 . A process for the production of a chemical-resistant bioreactor carrier having a degree of volumetric swelling controlled to within the range of 120 to 3,000% and a specific gravity upon swelling in water controlled to within the range of 0.98 to 2.12, the process comprising the steps of: 
 blending the water-swellable thermoplastic resin (A) as set forth in  claim 1 , the compatible resin (B) as set forth in  claim 1 , and an inorganic filler (C);    heat melting the resultant blend;    extruding the melted blend into the form of a strand by means of an extruder; and    continuously cutting the strand.    
     
     
         8 . A process for the production of a chemical-resistant bioreactor carrier having a degree of volumetric swelling controlled to within the range of 120 to 3,000% and a specific gravity upon swelling in water controlled to within the range of 0.98 to 2.12, the process comprising the steps of: 
 blending the water-swellable thermoplastic resin (A) as set forth in  claim 1  in which an inorganic filler is added at the time of producing the resin (A) with the compatible resin (B) as set forth in  claim 1  or with the compatible resin (B) as set forth in  claim 1  and an inorganic filler (C);    heat melting the resultant blend;    extruding the melted blend into the form of a strand by means of an extruder; and    continuously cutting the strand.    
     
     
         9 . A process for purifying organic waste water with a high chemical content by microbial nitrification and denitrification of nitrogen components in the organic waste water, wherein the chemical-resistant bioreactor carrier as set forth in  claim 1  is used as a microbe immobilization carrier.  
     
     
         10 . The process according to  claim 9 , wherein the bioreactor carrier as set forth in  claim 1  is used repeatedly and alternately in the nitrification and the denitrification.