Anaerobic waste digestion in Germany - Status and recent developments

Anaerobic treatment processes are especially suited for the utilization of wet organic wastes from agriculture and industry as well as for the organic part of source-separated household wastes. The anaerobic degradation is a very cost-effective method for treating biogenic wastes because the formed biogas can be used for heat and electricity production and the digester res idues can be recycled to agriculture as a secondary fertilizer. The anaerob ic technology will be used today also for the common treatment of wastes to gether with renewable energy crops in order to reduce the CO2-emissions acc ording the Kyoto protocol. Various process types are applied in Germany whi ch differ in material, reaction conditions and in the form of the used reac tor systems. The widespread introduction of anaerobic digestion in Germany has shown that biogenic organic wastes are a valuable source for energy and nutrients. Anaerobic waste treatment is done today in approx. 850 biogas p lants on small farm scale as well as on large industrial scale with the bes t beneficial and economic outcome. Due to some new environmental protection acts which promote the recycling of wastes and their utilization for renew able energy formation it can be expected that several hundreds new biogas p lants will be built per year in Germany. For using the synergetic effects o f a combined fermentation of wastes and energy crops new process types must be developed in order to optimize the substrate combinations and the proce ss conditions for maximum biodegradation.