Process and apparatus for further processing of sewage sludge and other materials to reduce pathogens and toxins

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.