NOVELTY - The apparatus comprises an acidification reactor of a mixed fluid type reactor for microbial hydrolysis and acidification of biomass, a methane synthesis reactor of a solid bed reactor type for an anaerobic microbial conversion of acidified biomass into methane, a methane synthesis reactor of a mixed fluid type reactor for anaerobic microbial conversion of acidified liquid biomass into methane, a nitrification reactor for aerobic microbial conversion of ammonia (NH4+) into nitrate (NO3-), and an effluent gas conversion reactor.    USE - The apparatus is useful for conversion of biomass including liquid manure, manure, sewage sludge, domestic vegetable waste, agricultural plant residue, and/or domestic plant residue into methane and/or fertilizer, where the methane is collected at the outlets of the methane synthesis reactors and the fertilizer is collected at the outlets of the nitrification reactor and/or the composting reactor (all claimed).    ADVANTAGE - The apparatus efficiently and economically converts the biomass into the methane and/or the fertilizer with increased yield.    DETAILED DESCRIPTION - The apparatus comprises an acidification reactor of a mixed fluid type reactor for microbial hydrolysis and acidification of biomass, a methane synthesis reactor of a solid bed reactor type for an anaerobic microbial conversion of acidified biomass into methane, a methane synthesis reactor of a mixed fluid type reactor for anaerobic microbial conversion of acidified liquid biomass into methane, a nitrification reactor for aerobic microbial conversion of ammonia (NH4+) into nitrate (NO3-), an effluent gas conversion reactor for aerobic microbial conversion of hydrogen sulfide (H2S) into sulfate (SO42-), a composting reactor for microbial decomposition of processed sludge biomass, a vacuum device for concentrating the processed liquid biomass, a controlling device configured to monitor pHs, temperatures and/or redox potentials, an outlet for discharging carbon dioxide (CO2) and methane, and an outlet for discharging calcium carbonate and ammonium magnesium phosphate. The acidification reactor: comprises an intake comprising a communicating inlet for receiving the biomass, a discharge end comprising an outlet for discharging acidified biomass, an outlet for discharging the H2S comprising gaseous effluent, and a further inlet for receiving acetate comprising leachate from the composting reactor; and is operated at a temperature of 45-70 degrees C and a pH of 3-4.5. The methane synthesis reactor of the solid bed reactor type: comprises an intake for receiving the acidified biomass from the acidification reactor, and a discharge end comprising outlets for discharging processed sludge biomass and methane comprising gaseous effluent and acidified liquid biomass; and is operated at the temperature of 20-60 degrees C, the pH of 6.5-8 and a redox potential of -150 mV to -450 mV. The methane synthesis reactor of the mixed fluid type reactor: comprises an intake comprising a communicating inlet for receiving acidified liquid biomass from the methane synthesis reactor of the solid bed reactor type and a discharge end comprising outlets for discharging processed liquid biomass and methane comprising gaseous effluent; and is operated at the temperature of 20-60 degrees C, the pH of 6.5-8 and the redox potential of -150mV to -450mV. The nitrification reactor comprises: an intake comprising a communicating inlet for receiving processed liquid biomass from the methane synthesis reactor of the mixed fluid type reactor and a discharge end comprising an outlet for discharging nitrified processed liquid biomass; and is operated at the temperature of 15-37 degrees C, the pH of 6.5-7.5 and the redox potential of greater than 50 mV. The effluent gas conversion reactor: comprises an intake comprising a communicating inlet for receiving H2S comprising gaseous effluent from the acidification reactor and a discharge end comprising an outlet for discharging CO2, water vapor (H2O) and sulfate (SO42-); and is operated at the temperature of 15-35 degrees C, the pH of 3-4.5 and the redox potential of greater than 50 mV. The composting reactor: comprises an intake comprising a communicating inlet for receiving processed sludge biomass from the methane synthesis reactor of the solid bed reactor type, a discharge end comprising an outlet for discharging composted biomass, and an outlet for discharging acetate comprising leachate; and is operated at the temperature of 45-75 degrees C, the pH and an oxygen concentration of 2-20%. The methane synthesis reactor of the solid bed reactor type further comprises: a phase separation device for separating the acidified biomass into an acidified liquid biomass and an acidified sludge biomass and a methane synthesis device. The phase separation device comprises an inlet for receiving acidified biomass and outlets for discharging acidified liquid biomass to the methane synthesis reactor of the mixed fluid type reactor and acidified sludge biomass. The methane synthesis device comprises an inlet for receiving the acidified sludge biomass from the phase separation device and an outlet for discharging processed sludge biomass, and is operated at the temperature of 20-60 degrees C, the pH of 6.5-8 and the redox potential of -150mV to -450mV. The vacuum device: is positioned between the methane synthesis reactor of the mixed fluid type reactor and the nitrification reactor; comprises an inlet for receiving processed liquid biomass from the methane synthesis reactor of the mixed fluid type reactor and an outlet for discharging concentrated processed liquid biomass to the nitrification reactor; and is operated to subject the processed liquid biomass to a vacuum of 20-200 mbar until the pH of 8.5. The reactors are provided with heating devices for maintaining the temperature in the defined range, with pH regulating devices for maintaining the pHs in the defined range, and with redox potential regulating devices for maintaining the redox potential in the defined range. The communicating inlets and outlets of the reactors comprise devices for isolation of microorganisms and reintroduction of the isolated microorganisms in the reactors from which they are derived from the reactors. An INDEPENDENT CLAIM is included for a method for conversion of biomass.