NOVELTY - Anaerobic digester system comprises (a) hydrolysis reactor comprising hydrolytic bacterial culture for which the organic material is a hydrolysis substrate, (b) biogasification reactor comprising acetogenic and methanogenic bacterial culture, and (c) biostabilization reactor comprising methanogenic bacterial culture.    USE - The anaerobic digester system is useful for producing biogas from organic material. The biogas includes methane, hydrogen and carbon dioxide.    ADVANTAGE - The anaerobic digester system produces biogas rapidly and cost-effectively.    DETAILED DESCRIPTION - Anaerobic digester system comprises (a) hydrolysis reactor (35) comprising hydrolytic bacterial culture for which the organic material is a hydrolysis substrate, where the hydrolysis reactor further comprises hydrolysis inlet port (40) for receiving the organic material, hydrolysis outlet port (42) for discharging hydrolysis effluent from the hydrolysis reactor, first hydrolysis outlet port for discharging hydrolysis effluent from the hydrolysis reactor and gas vent for discharging the biogas from the hydrolysis reactor, (b) biogasification reactor (46) comprising acetogenic and methanogenic bacterial culture, where the biogasification reactor further comprises biogasification reactor inlet port for receiving the hydrolysis effluent from the hydrolysis reactor outlet port, biogasification reactor outlet port for discharging biogasification effluent from the biogasification reactor, and gas vent for discharging the biogas from the biogasification reactor, and (c) biostabilization reactor (58) comprising methanogenic bacterial culture, where the biostabilization reactor further comprises first biostabilization reactor inlet port for receiving the biogasification effluent from the biogasification reactor outlet port, biostabilization reactor outlet port for discharging biostabilization effluent from the biostabilization reactor, and gas vent (44) for discharging the biogas from the biostabilization reactor. INDEPENDENT CLAIMS are included for the following:    (1) method for producing a biogas; and    (2) biostabilization reactor system for producing a biogas from a partially-digested organic material.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of anaerobic digester system.    Hydrolysis reactor (35)    Hydrolysis inlet port (40)    Hydrolysis outlet port (42)    Gas vent (44)    Biogasification reactor (46)    Biostabilization reactor (58)