Today biogas formation is exploited as a spontaneous microbiological process. An intensification by microbiological means leads to significantly improved, economically feasible technologies. The complex cascade of anaerobic microbiology events that leads to degradation of organic waste (manure and other agricultural waste, waste water sludge, waste from the food processing industry and households) yielding biogas is far from being understood. This is due to the fact that microbiology research has only begun to investigate the behaviour of mixed microbial systems, recently. Overall, it is known that methanogenic bacteria at the end of the series of interrelated microbiological conversion steps need reductant to form methane, the most reduced form of a carbon atom. Reductants are usually supplied as hydrogen by acetogenic bacteria present in the methanogenic consortia. Among the significant recent advances in the microbiology of anaerobic biodegradation of organic wastes are the recognition of the close syntropic relationship among three distinct microbe populations and the importance of hydrogen H₂ in the process control. It is shown that addition of hydrogen producers to the system and thereby shifting the population balance brings about advantageous effects for the entire methanogenic cascade. The decomposition rate of the organic substrate and both the acetogenic and methanogenic activities are remarkably amplified.

In order to reduce the cost for production of the hydrogen producers, the bacteria should be grown separately in diluted industrial waste water. This substrate is added discontinuously into the digester in order to increase the decomposition rate and the biogas production.

The technology is recommended to be developed first for small farms with animal breeding above 200 SD (SD = animals of a weight over 500 kg). The technology should also be used with advantage in municipalities for treatment of mixed organic waste such as manure, sewage sludge, municipal solid waste, waste from agriculture and food industries etc.

The R&D objectives of this task will be 1) better understanding of the microbiological events under AD conditions in mixed cultures; 2) optimization of the degradation and bioconversion yields; 3) development of a simple but reliable fermenter design for small farm users; 4) installation of demonstration plants; 5) feasibility and economical calculations based on the demonstration plants’ performance characteristics under various environmental and sociological conditions at geographically distant locations; 6) increasing public appreciation and awareness through