Biogas Reactor Technology for Norwegian Agriculture

In order to reduce the greenhouse gas emissions much of the manure in Norway should be treated by anaerobic digestion (AD). The AD plant economy can be enhanced by increased biogas production obtained by co-digestion of energy rich substrates like fish ensilage and/or food or slaughterhouse waste. However, the anaerobic digestion is sentitive to the high concentration of the ammonia which is produced during the degradation of the protein rich materials mentioned.
Microorganisms that tolerate high concentrations of ammonia in AD are slow-growing and easily washed out in continuous digesters with suspended bacterial systems. The development of ammonia tolerant microorganism living in biofilms is proposed as a solution to this challenge. In the project the potential role of ammonia tolerant cultures will be analyzed using different reactor technologies. The process design criteria for ammonia tolerant systems suitable for Norwegian agriculture will be suggested.
Increased loading is also possible if the process parameters are monitored on-line, making it possible with early and adequate response to environmental changes. The development and use of new sensor technology and process controlling system is another important part of the project.
Effective AD reactors of UASB type equipped with advanced process control systems might be connected to the already existing farm infrastructure. These biofilm reactores have low investment cost and can operate at smaller farms. This technology is further developed for implementation in Norwegian agriculture.
Horses, sheep, goats and poultry, or animal with deep litter produces manure with high dry matter content. High solids AD requires small energy inputs and will reduce transport costs of the produced digestate due to low water content. However, ammonia inhibition might be an important challenge. Such processes will be tested in the laboratory and evaluated for full scale treatment of solid state manure.