TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Process: The process (P1) or (P2) further involves: maintaining the pH of the reactor bulk liquid within 6.5-8.5. The process (P1) or (P2) further involves: maintaining the oxidation-reduction potential of the reactor bulk liquid at -300 to -400 mV. The process (P1) or (P2) in the reactor is performed mesophilic at 80-100 degrees F. The process (P1) or (P2) in the reactor is performed thermophilic at 125-150 degrees F. The process (P1) or (P2) further involves: monitoring rate of the reactor biogas production to determine whether rate of production of the biogas is within a predetermined range. The process (P1) or (P2) further involves: monitoring relative rates of methane, carbon dioxide, and hydrogen sulfide production of the reactor biogas to determine whether methane, carbon dioxide, and hydrogen sulfide production are each within a predetermined range. The process (P1) further involves: removing treated effluent from the reactor; and recycling at least a portion of the treated effluent to the reactor to increase biomass inventory within the reactor. The process (P1) further involves: passing treated effluent through a solids/liquid separation apparatus for further treatment of the effluent. Preferred Components: The biogas comprises methane of 60-85%; and carbon dioxide of 15-40%.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Apparatus: The apparatus further comprises a recycle effluent conduit for recycling a portion of the treated effluent back to the reactor; further comprises a flow meter operably coupled to the biogas conduit for measuring the level of flow of biogas from the reactor; and further comprises a methane sensor operably coupled to the biogas conduit for measuring the amount of methane in the biogas; and a carbon dioxide sensor operably coupled to the biogas conduit for measuring the amount of carbon dioxide in the biogas; and a hydrogen sulfide sensor operably coupled to the biogas conduit for measuring the amount of hydrogen sulfide in the biogas. The apparatus further comprises: several injection conduits which facilitate injection of process chemicals selected from caustic, magnesium hydroxide, micronutrients, ferrous chloride, ferric chloride, macronutrients, and lime. The apparatus further comprises: a microprocessor connected to the oxidation-reduction potential, pH, and temperature sensors. Preferred Components: The microprocessor automatically adjusts the rate of feed material into the reactor in response to predetermined ranges of parameters selected from temperature, pH or oxidation reduction potential (ORP). The microprocessor automatically adjusts the rate of feed material into the reactor in response to predetermined ranges of parameters selected from biogas flow rate, methane (CH4) or carbon dioxide (CO2). The microprocessor automatically adjusts the rate of feed material into the reactor in response to predetermined ranges of parameters selected from biogas production rate, methane production rate, chemical oxygen demand (COD), volatile solids (VS), volatile fatty acids (VFAs) or alkalinity. EXAMPLE - No suitable example given.