Development and Scaleup of a High‐Rate Biogas Process for Treatment of Organically Polluted Effluents

Due to the high concentration of industrial production in localized small urban areas in recent years, highly polluted effluents are produced. Modern waste management should therefore consider these localized situations in a special way. Conventional aerobic wastewater treatment (activated sludge process) becomes more and more problematic due to the considerable energy requirements for oxygen supply. The main goal of the so-called high-rate biogas process was thus to provide a technical solution for treatment of organically polluted industrial effluents. In the case of anaerobic “activation”, degradation of wastewater components is performed according to a concept that has already been realized in nature: biogas is the end product of degradation of organic material in the absence of oxygen. Aerobic methods only partly solve pollution control problems because up to 50% of the organic matter is transformed into sewage sludge. The problems are thereby shifted in part to the excess sludge produced. However, anaerobic wastewater treatment appears to be a general purification method insofar as the major part of organic pollution (more than 95%) is eliminated under energy-saving conditions. The endproduct biogas contributes to the process by making it self-sufficient with regard to energy. The low carbon incorporation (only 3-4%) into cell mass is associated with the energy limitation of growth under anaerobic conditions. On the other hand, in spite of some prejudices, the metabolic activity of anaerobes is undoubtedly comparable with that of anaerobic microorganisms. This also becomes clear if one considers that evolution under energy-limiting conditions encourages the selection of some mutants that perform at a particularly high substrate conversion rate from the low energy potential available.