Patent ID: 7361801

Claim:
A method of immobilizing nitrate ions or nitrite ions in aqueous waste comprising the steps of: (a) mixing the aqueous waste with a compound selected from the group consisting of Me(II)O and Me(II)(OH) 2 and a compound selected from the group consisting of 1) a compound having the formula Me(II)O.R 2 O 3 , and 2) a compound having the formula R 2 O 3 , R(OH) 3 or ROOH, to provide an aqueous waste mixture, where Me(II) is a cation selected from the group consisting of Ca, Ba, Sr, Mn, Zn and combinations thereof, and where R is selected from the group consisting of Al, Fe, Cr and combinations thereof; and (b) allowing the aqueous waste mixture to form a solid with a crystalline structure which incorporates the nitrate ions or nitrite ions from the aqueous waste within the crystalline structure of the solid, wherein the following reaction immobilizes the nitrate ions or nitrite ions in the aqueous waste: where x is 2 or 3 and n is at least 10.