NOVELTY - To recover useful material from animal garbage tankage, it is formed into a slurry by mixing (1) with water, for anaerobic fermentation in a container (2). The gas from the fermentation is led away and heated (3), and solids are separated (4) from the slurry residue from fermentation. The liquid obtained from the separation is treated up to an acceptable hygienic level.    USE - The system is for the recovery of useful material in the disposal of animal garbage tankage.    ADVANTAGE - The content of organic substances is reduced by biological degrading of about 60% of the organic matter, so that only 40% of the original material is to be incinerated.    DETAILED DESCRIPTION - To process animal garbage tankage, the separated liquid is processed in a multi-stage filtration (5) to remove at least colloids and proteins including prions, using membrane filters. The filtration is followed by reverse osmosis (6). At least part of the heat generated from the gas processing is recovered for use at the fermentation stage to heat the fermenting container, and also at the drying stage for the separated solids. The retained matter at the filtering stage is passed to the fermented residue, before its separation. The condensation from the gas processing stage is passed to the separated liquid, after the separation stage. At least part of the solid matter from the reverse osmosis is added to the separated solids and to the fermented residue before separation. The recovered solid matter is heat processed if required after drying. The gas extracted from the fermentation stage, composed mostly of carbon dioxide and hydrogen sulfide and water vapor, is passed to a system to generate current and heat through a force-heat coupling.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow chart of the processing stages to treat animal garbage tankage. (The drawing includes non-English language text).    slurry mixing container (1)    fermenting stage (2)    heater (3)    separator (4)    filter stage (5)    reverse osmosis (6)