NOVELTY - Biosolids are processed by method involving forming acidified paste of dewatered biosolids and first acid; adding acidified paste to pressure vessel such that the vessel maintains a head space which has predetermined pressure; adding second acid and base to pressure vessel to combine with the acidified paste and form a mixture; subjecting the mixture to a temperature and pressure for retention time, where temperature and moisture content of mixture are determined by head space pressure; removing the mixture from pressure vessel; and drying the mixture to form treated and dried biosolids.    USE - For processing biosolids such as municipal biosolids, heat-dried biosolids, pharmaceutical fermentation wastes, microbial digests of organic products, food stuffs, food byproducts, animal manures, digested animal manures, organic biosolids, and biosolids containing microorganisms (claimed) into high-value, nitrogen-containing, slow-release, organically-augmented inorganic fertilizer.    ADVANTAGE - The exothermic design and closed loop control of the primary reaction vessel decreases significantly the amount of power necessary to run the manufacturing facility. The process utilizes green technologies to facilitate decreased waste and enhanced air quality standards over traditional processing plants. The fertilizer produced from recovered biosolid waste is safe and meets or exceeds the United States Environment Protection Agency (USEPA) Class A and Exceptional Quality standards. The method eliminates the transportation requirement by locating the physical equipment necessary to perform the manufacturing process adjacent or close to the source of the biosolids such as municipal wastewater treatment plants. By co-locating a processing facility of the present method, the otherwise unwanted by-products such as ammonium sulfate need not be carted away, but can be directly utilized in the manufacture of fertilizer. The method produces a fertilizer that exceeds the USEPA regulation, thus is safe for use in and around farming, plants, animals, and safe for handling by humans; and biosolids treated by the present method typically contain low levels of metals such as arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium and/or zinc.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) system for processing biosolids into fertilizer, comprises a first mixer that blends the biosolids with concentrated acid and oxidizing agents and converts the biosolids into a pumpable paste; pressure vessel with head space pressure that receives the pumpable paste from the first mixer, where the pressure vessel retains the pumpable paste at predetermined pressure and temperature as determined by the head space pressure and for a period of time; second mixer that receives the pumpable paste from the pressure vessel, where the pumpable paste is mixed with a hardening agent; and granulator to break the hardened paste into pelletized fertilizer; and    (2) pressure vessel for processing biosolids comprises a head space and several valves that control head space pressure, where head space pressure determines the temperature and moisture content of biosolids within the vessel, and further comprises gauges that indicate temperature, pressure, pH, and nitrogen content of the biosolids within the pressure vessel.