Protein feed and bioplastic from farm biogas.

Protein feed and bioplastic from farm biogas. A new solution has been developed for converting even small sources of methane-rich biogas into raw materials for animal feed or bioplastic on farms, landfills and wastewater treatment plants. This emission-reducing solution is based on the ability of methanotrophic bacteria to grow on methane in gas fermentors. Methane-rich biogas is generated on farms, landfills and wastewater treatment plants in anaerobic digestion of biological material. Until now, the processing of such gas into biomethane has only been viable on large biogas-producing sites; small biogas sources such as farms have remained largely unexploited. Technical Research Centre of Finland (VTT), has developed a solution for converting even small sources of methane-rich biogas into raw materials for animal feed or bioplastic on farms, landfills and wastewater treatment plants. This emission-reducing solution is based on the ability of methanotrophic bacteria to grow on methane in gas fermentors. Methane-rich biogas is generated on farms, landfills and wastewater treatment plants in anaerobic digestion of biological material. Until now, the processing of such gas into biomethane has only been viable on large biogas-producing sites; small biogas sources such as farms have remained largely unexploited. The method developed by VTT would reduce emissions, increase the use of biogas and improve protein self-sufficiency. It is based on the ability of methanotrophic bacteria to grow in aerobic conditions in gas fermentors, using methane as the source for carbon and energy. The process is as follows: The methane gas generated by anaerobic digestion is fed into a gas fermentor. A growth medium containing the methanotrophic bacteria circulates through the pipes of the gas fermentor, creating a single-cell protein biomass with a protein content of around 60%. The cell mass is filtered, pasteurised and dried. The methanotrophic bacteria and (depending on the growth conditions) cell mass may also contain polyhydroxybutyrate plastic (PHB) -- a natural substance in the cells that enables them to store conserve energy. For example, PHB can be used as a raw material for biodegradable packaging material, instead of oil-based and non-biodegradable plastics such as polypropylene (PP). The cell mass may contain 50% half of the PHB, in which case the protein content is around 30%. Extraction is used to separate the PHB and protein fractions from the dried cell mass.