Thermally treated expanded perlite

Abstract

A thermally treated expanded perlite that can be coated or impregnated with at least one active material and the use of the thermally treated expanded perlite as a light-weight filtration media. Methods for forming thermally treated expanded perlite as well as methods for forming thermally treated perlite coated or impregnated with an active material are also disclosed.

What is claimed is:  
     
         1 - 6 . (canceled) 
     
     
         7 . A method for forming expanded perlite thermally impregnated with an active material comprising:
 forming a mixture comprising (i) expanded perlite and (ii) an active material or an active-forming material to produce a composition containing perlite pellets coated with the active material or active-forming material; and   heating the composition containing the coated perlite pellets to a temperature of about 850 to 1300° C. to produce expanded perlite pellets thermally impregnated with the active material.   
     
     
         8 . A method in accordance with  claim 7  wherein said active material comprises an element selected from the group consisting of calcium, magnesium, aluminum, iron and mixtures thereof. 
     
     
         9 . A method in accordance with  claim 7  wherein the average particle size of the expanded perlite pellets thermally impregnated with an active material is about 0.5 mm to about 12.5 mm. 
     
     
         10 . A method in accordance with  claim 7  wherein the expanded perlite pellets thermally impregnated with an active material have a crush strength of at least 6 lbs. 
     
     
         11 . A method in accordance with  claim 7  wherein said mixture comprises an active material and said active material comprises calcium or magnesium or both. 
     
     
         12 . A method in accordance with  claim 7  wherein said mixture comprises an active-forming material and said active-forming material is selected from the group consisting of  calcium acetate, calcium carbonate, calcium bicarbonate, calcium hydroxide and mixtures thereof. 
     
     
         13 . A method in accordance with  claim 7  wherein said mixture comprises an active-forming material and said active-forming material is selected from the group consisting of magnesium acetate, magnesium carbonate, magnesium bicarbonate, magnesium hydroxide and mixtures thereof. 
     
     
         14 . A method in accordance with  claim 7  wherein said active material comprises calcium oxide, magnesium oxide or both. 
     
     
         15 . A method in accordance with  claim 7  wherein said mixture comprises an active material selected from the group consisting of activated alumina, goethite, iron oxide-hydroxide and mixtures thereof. 
     
     
         16 . A method for removing contaminants from an aqueous composition comprising:
 contacting an aqueous composition containing contaminants with a filtration media comprising expanded perlite thermally impregnated with at least one active material.   
     
     
         17 . A method in accordance with  claim 16  wherein said filtration media has a bulk density in the range of about 5 to 40 lbs/ft3 and an average particle size of about 0.5 mm to about 12.5 mm. 
     
     
         18 . A method in accordance with  claim 16  wherein said aqueous composition containing contaminants comprises stormwater runoff or wastewater. 
     
     
         19 . A method in accordance with  claim 16  wherein the contaminants comprise phosphorus. 
     
     
         20 . A method in accordance with  claim 16  wherein the contaminants comprise dissolved metals.  
     
     
         21 . A method in accordance with  claim 20  wherein the dissolved metals are selected from the group consisting of copper, zinc, lead, nickel, cadmium and mixtures thereof. 
     
     
         22 . A method in accordance with  claim 16  wherein the active material comprises alumina. 
     
     
         23 . A method in accordance with  claim 22  wherein the alumina comprises activated alumina. 
     
     
         24 . A separation system for separating contaminants from an aqueous composition comprising:
 a tank with an inlet for receiving the aqueous composition and an outlet for transferring treated water out of the tank; and   a treatment chamber disposed in the tank wherein the treatment chamber contains a light-weight filtration media comprising expanded perlite thermally impregnated with at least one active material.   
     
     
         25 - 38 . (canceled)