THERMALLY TREATED EXPANDED PERLITE
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.
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)