Description It demonstrates the biological anaerobic water treatment. The trainer consists basically of two units: – stirring tank with secondary clarifier – UASB reactor Both units can be used separately or in combination. This allows both a single stage and a dual stage operation mode. In the dual stage operation a pump first transports the raw water into a stirred tank. In this tank the acidification of the organic substances dissolved in the raw water takes place. Here, anaerobic microorganisms convert the long-chain organic substances into short-chain organic substances. In a secondary clarifier the biomass discharged from the stirred tank is separated from the water. The separated biomass is pumped back into the stirring tank. From the secondary clarifier the raw water pretreated in this manner reaches a UASB reactor (UASB: Upflow Anaerobic Sludge Blanket). Here the final step of the anaerobic degradation takes place. The previously formed short-chain substances are converted by special microorganisms into biogas (methane and carbon dioxide). Flow through the UASB reactor is from the bottom to the top. At the top of the UASB reactor there is a separation system. This separates the generated gas from the treated water. It also ensures that the biomass remains in the reactor. The gas can be discharged externally or collected. The treated water exits at the top end of the reactor and is collected in a tank. To adjust the flow velocity in the UASB reactor a of the treated water can be recirculated. The temperatures in the stirred tank and the UASB reactor can be controlled. The pH value in the stirred tank is measured. In addition, the pH value in the UASB reactor can be controlled. A software and webcam are available for data acquisition and visual inspection.Anaerobic biomass and analysis technology are required to perform the experiments. Recommended parameters are: COD (chemical oxygen demand), nitrogen and phosphor. Specification anaerobic degradation of organic substances stirred tank with secondary clarifier UASB reactor with separation system separate supply unit with tanks for raw water and treated water single stage or dual stage operation mode temperatures in the stirred tank and the UASB reactor can be controlled control of the pH value in the UASB reactor GUNT software for data acquisition via USB under Windows 8.1, 10 visual inspection with webcam