NOVELTY - Organic by-product processing plant comprises a processing vessel (200) in which the by-product can be processed. The processing vessel comprises a vessel wall (204), a lifting mechanism located in a central region of the vessel and arranged to lift the by-product within the vessel, and a metal heat transfer member (209) extending around the lifting mechanism in an outer region of vessel and rotatable around the outer region of the vessel to resist downward movement of the by-product in the outer region of the vessel and dissipate heat through the by-product in the outer region of the vessel.    USE - The organic by-product processing plant is useful for processing organic by-product (claimed), animal by-products, food waste and other organic by-products for producing fertilizer.    ADVANTAGE - The organic by-product processing plant utilizes processing vessel which aids in conducting heat through the mixture and allowing it to be heated quickly and uniformly to the required temperature, thus reducing the time required for the heating step.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) the processing vessel for processing organic by-product;    (2) processing organic by-product comprising introducing the by-product into the vessel, introducing a further product into the vessel to form a mixture, lifting the mixture upwards in the central region of the vessel by means of the lifting mechanism, resisting downward movement of the mixture in an outer region of the vessel by means of the heat transfer member, and transferring heat within the mixture using the heat transfer member; and    (3) a processing plant for processing organic by-product, comprising a heating vessel having a product inlet arranged to receive the by-product, a water inlet arranged to receive water, a steam inlet arranged to receive steam, heating means arranged to heat the first heating vessel, a separator arranged to receive the contents of the first heating vessel and separate it into first and second components, and an acidification vessel having a product inlet arranged to receive the solid component, and acid inlet means arranged to receive acid.    DESCRIPTION OF DRAWING(S) - The figure a cut-away side view of a heating vessel forming part of the plant.    Processing vessel (200)    Vessel wall (204)    Heat transfer blades (206)    Metal heat transfer member (209)    Scraper blades (214)