Patent ID: 7972408

Claim:
A method of treating a Biosolid composition contaminated with one or more pathogenic microorganisms comprising the steps of: placing the composition into a pressure sealable treatment vessel having a reagent injection system, a mixing device, a heating system, and a vapor recovery system; controlling the pressure or temperature in the vessel such that anhydrous ammonia inside will exist in a substantially gaseous state; injecting anhydrous ammonia into the vessel through the reagent injection system; mixing the composition in the presence of anhydrous ammonia using the mixing device to kill at least a portion of the pathogenic microorganisms in the composition; and recovering anhydrous ammonia gas that has not reacted in the composition through the vapor recovery system; introducing phosphoric acid into the vessel following the step of mixing the composition in the presence of anhydrous ammonia; and mixing the composition with the phosphoric acid using the mixing device to convert residual ammonia in the composition into a nitrogenous fertilizer salt.