NOVELTY - Anaerobic digestion (A1) of biomass involves providing biomass as feed stream; aerobically hydrolyzing at least one portion of stream in a hydrolysis stage; transferring at least one portion of stream after hydrolysis to acidifying stage; anaerobically acidifying at least one portion of stream at first temperature; transferring at least one portion of stream after acidifying to thermophilic stage; and anaerobically converting at least one portion of stream at a second temperature, where converting includes forming at least one acetic acid, methane and carbon dioxide.    USE - For anaerobic digestion of biomasses for production of biogas (e.g. methane, hydrogen), liquid fertilizer, pathogen-reduced liquid fertilizer, biosolids, Class A Biosolids, and pathogen reduced biosupplements (claimed).    ADVANTAGE - The method produces biomass digesters with increased efficiency, which enables reduction in digester volume and/or reactor size. Such reduction leads to reduced capital costs and reduced energy requirements, as a consequence of lower heating and mixing demands. Through the digestion of waste materials using sequential phases in an efficient digestion process, enhanced biomass conversion efficiency and improved output of products (in quantity and/or quality) are obtained with a significant reduction in dwell time in each phase. The independence of phase environments and separate control of phases provides a stable operation by minimizing process upsets (e.g. microbe displacement and spillover that normally be caused by unequal microbial growth) and provides uninterrupted operating period that maximizes biogas, biosolid and/or biofuel production. The system and the method provides stable anaerobic digestion and uninterrupted plant operation with reduced plant upsets, upsets that are normally due to unequal growth rates of microorganism; reduces overall amount of water consumed in digestion processes; avoids over-acidification as well as minimal operating energy requirements. Such enhancement promotes system efficiency and stability. The method provides efficient and on-demand biomass digestion and output production without a need for regular biomass biosupplements; allows digestion and output production with minimal operating energy requirement; and allows reliable production of biogases, biofuels and/or biosolids, including safe organic fertilizer. The method improves overall biomass digestion, enhances generation rate of methane and/or hydrogen and output of safe organic liquid fertilizer, Class A biosolids and other pathogen reduced fertilizers and/or biosupplements. The efficient and controllable digestion processes and systems, each having more moderate and modifiable reactor conditions, removes potential for over-acidification and assists in isolating acidogenic microbes in order to manage their rapid and aggressive growth. In addition, efficient and timely biomass digestion is obtained without the need for regular biomass supplements.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method of recycling water in a biomass digestion process involving transferring at least one portion of post-mesophilic stage effluent from a biomass digestion process to a dewatering stage, separating liquid from solids in the dewatering stage, transferring at least one portion of the separated liquid to at least one biological contactor, filtering at least one portion of liquid through the biological contactor, filtering again the liquid through an earth filter; and transferring the filtered water to the biomass digestion process for re-use;    (2) a system (A2) for anaerobic digestion of biomass comprising at least one hydrolysis stage vessel for receiving a feed stream that includes a biomass, and aerobically hydrolyzing at least one portion of the feed stream, at least one anaerobic acidic stage vessel for receiving at least one portion of feed stream from the hydrolysis stage vessel, and anaerobically acidifying at least one portion of the feed stream received from the hydrolysis stage vessel to generate an acidified feed stream, at least one pH adjustment system for modifying pH of at least one point in the system located at or between the vessels, at least one heat exchanger for modifying temperature of at least one point in the system, at least one anaerobic thermophilic stage vessel for receiving at least one portion of the acidified feed stream, and anaerobically converting at least one portion of the acidified feed stream to acetic acid, a biogas and carbon dioxide, a gas lifter for removing at least one biogas from the anaerobic thermophilic stage vessel, a treating system operable to filter the biogas, and a diversion system operable for diverting at least one portion of the feed stream exiting at least one of the anaerobic thermophilic stage vessel to a dewatering system, where the dewatering system separate solids from liquid in the received feed stream to produce a product that includes at least one product selected from liquid fertilizer, a pathogen-reduced liquid fertilizer, biosolids, Class A biosolids, and biosupplements; and    (3) method (B1) for production of biogas involving providing a first biodigestion system and a second biodigestion system in parallel, where the first biodigestion system has a first feed stream with a high percent total suspended solids as compared with a second feed stream for the second biodigestion system, where each biodigestion system includes an aerobic hydrolysis stage, an anaerobic acidogenesis stage and at least one anaerobic methanogenesis stage, and each biodigestion system produces at least one biogas at one of the group consisting of the acidogenesis stage and the methanogenesis stage; and removing at least one portion of the biogas produced from the first biodigestion system for routing to the second biodigestion system.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view for the process of biomass digestion.