NOVELTY - Converting biological feedstock (2) into at least one combustible gas and nutrient rich solid, comprises: (a) subjecting the feedstock to digestion in a biodigester (1) by anaerobic bacteria to afford at least methane and at least partially digested feedstock; (b) reacting the digested feedstock with a halogen e.g. chlorine, bromine and/or iodine to produce heat, aqueous hydrogen halide and a micronutrient rich ash; and (c) electrolytically converting the hydrogen halide to gaseous hydrogen and molecular halogen.    USE - The process is useful for converting biological feedstock into at least one combustible gas (methane) and nutrient rich solid, where the gas is useful as a fuel (all claimed).    ADVANTAGE - The process provides a significant reduction in the volume of the waste solids hence reducing costs associated with disposal or distribution. The pathogens existing in anaerobic digester effluents are destroyed by both the heat and oxidation resulting from the halogen oxidation process. The residual solids output from the halogen digester comprise a substantially or totally pathogen free, micronutrient-rich ash that is used as a fertilizer. The liquid portion, which contains the aqueous hydrogen halide acid, is passed on to an electrolysis chamber for generating hydrogen and regenerating the halogen for recycling and reuse in the oxidation process. The methane and hydrogen gas mixture produced by the combined process produces significantly reduced harmful emissions over conventional fuels e.g. diesel and gasoline. The process: allows for warm and stable digestion temperatures, thus enabling the process to be carried out in colder climates; produces an effluent with fewer or no pathogens; has shorter retention times for feed stock; and provides a method to extract an increased amount of energy per unit of feedstock.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) converting biological feedstock into a nutrient rich solid, comprising subjecting the feedstock to partial digestion by aerobic bacteria to afford an at least partially digested feedstock, subjecting the aerobically digested feedstock to further partial digestion by anaerobic bacteria, and steps (b) and (c) as above per se; and    (2) an apparatus for the processing of biological feedstock in operable combination, comprising an aerobic or anaerobic bacteria digestion unit, a halogen oxidation unit and an electrolysis unit for converting aqueous hydrogen halide produced in the halogen oxidation unit into molecular halogen and hydrogen gas.    DESCRIPTION OF DRAWING(S) - The figure shows the overall process of the biological digestion system.    Biological digestion system (1)    Biowaste feedstock (2)    Electricity generator system (5)    Halogen electrolysis system (7)    Filter (35)