NOVELTY - The method comprises reacting a feedstock in a reactor (402) to form an effluent, separating the effluent into a solid fraction and a liquid fraction, separating heavy metals from the liquid fraction, separating 80 wt.% of arsenic, cadmium, cobalt, mercury, molybdenum and/or selenium from the liquid fraction, maintaining a temperature in the reactor that is less than 210 degrees C, maintaining a pressure in the reactor of 2070 kPa, supplying oxygen gas to the reactor, and recycling a portion of the effluent back to the reactor. The feedstock is a part of a reaction mixture.    USE - The method is useful for treating an organic waste such as a sewage material, a municipal and/or farm waste such as a dewatered sewage, a municipal sludge cake, an animal manure and a food waste such as potato skins, from home, industries and institutions and for transforming the sewage material into a fertilizer, a biofuel such as a biodiesel, biolubricants and/or a soil amendment.    ADVANTAGE - The method is capable of economically treating the organic waste with less acid consumption thus providing good fertilizer.    DETAILED DESCRIPTION - The method comprises reacting a feedstock in a reactor (402) to form an effluent, separating the effluent into a solid fraction and a liquid fraction, separating heavy metals from the liquid fraction, separating 80 wt.% of arsenic, cadmium, cobalt, mercury, molybdenum and/or selenium from the liquid fraction, maintaining a temperature in the reactor that is less than 210 degrees C, maintaining a pressure in the reactor of 2070 kPa, supplying oxygen gas to the reactor, and recycling a portion of the effluent back to the reactor. The feedstock is a part of a reaction mixture that includes a first oxidizing acid and nitric acid (1wt.%). The step of separating the heavy metals form the liquid fraction includes precipitating the heavy metals from the liquid fraction and contacting the liquid fraction with an ion exchange material and/or activated carbon. The solid fraction includes a hydrocarbon material that includes 25 wt.% of fatty acid esters. A weight ratio of the first oxidizing acid to the nitric acid when added to the reaction mixture is 2. The first oxidizing acid includes sulfuric acid. The feedstock includes a sewage material. A pH of the reaction mixture is 0.5 to 2.0.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a reaction system.    Reactor (402)    Oxygen gas source (406)    Control gas source (408)    Recycled gas source (410)    Sensors. (412)