TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The concentration and/or content of the microbial biomass and/or the separated microbial mass is determined by a measuring device. The obtained biogas is analyzed by an analysis mechanism for determining gas composition and/or gas production rate. The device comprises a conveyer system to promote a liquid in the expiration against a flow direction of the separated microbial biomass, which undergoes a magnetic field mechanism using a movable magnetic field. The intermediate treatment mechanism is carried out for cleaning or mincing microbial agglomerates using magnetic particles. The magnetic field strength support mechanism provides arrangements of magnets such as permanent magnets and/or electromagnets. The magnets are arranged in projection (16) along the expiration. The magnets is in: active position, when kept in the support of microbial biomass and passive position, when it is not in the support of the microbial biomass.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The concentration and/or content of the microbial biomass and the separated the microbial biomass in the reactor are determined by magnetic particle in the reactor. The concentration and/or the contents of the microbial biomass in the reactor is analyzed or evaluated by the biogas production. The biogas produced is analyzed or determined by gas composition and/or gas production rate. The amount of the microbial biomass used in the biogas production depends upon the concentration of the microbial biomass in the reactor. The microbial biomass expiration in the reactor is carried out by a supporting liquid through a flow direction in the outlet. The expiring microbial biomass is separated by implementing magnetic field. The separated quantity of the expired microbial biomass is partially treated before in contact with the reactors. The microbial biomass is treated by cleaning, a mincing microbial agglomerated with magnetic particle. The separated microbial biomass is in concentrated form.