In the western part of Germany there are 77 full scale anaerobic treatment plants treating industrial wastewater. The ISAH (Institut für Siedlungswasserwirtschaft und Abfalltechnik at the University of Hannover) is or was involved in the investigations, the design and/or operation of 14 of these plants. Some industries (sugar beet, starch, pectin, brewery, vegetable) with their special problems with treating their wastewater anaerobically are described. Experiences of how to handle high nitrate concentrations, to treat a mixture of several industrial wastewaters, to prevent or handle lime, magnesium ammonium phosphate (MAP) or aluminium precipitations are reported.

The first municipal wastewater treatment plant combined with a separate anaerobic stage to treat a wastewater mixture of several small factories is described. Something very special about this plant is the construction of the acidification tank. Using the “teapot effect” to enrich the solid material in the centre of the bottom, the solids can be taken from the bottom of the tank and pumped to the municipal sludge digester.