Development and test of a new mixing vessel for pretreatment of straw for biogas production

The objective of the project is to develop a special wheeled mixing vessel designed for pretreatment of straw before utilization in a biogas plant. The idea is that the feeder must be tight enough to allow straw mixed with slurry under maximum disintegration of the straw. Out comes a straw- manure slurry, which is lead to the farmers pre- storage tank before the tanker from the centralized biogas plant collects the manure. By this, the farmer is enabled to supply manure with a higher DM content, the biogas plants avoids costly handling and disintegration of straw at the biogas plant, and no empty loads are necessary as the straw no longer needs to be transported to the biogas plant separately. It will be investigated how the slurry affects the biogas potential of the straw, relative amounts, retention time etc. From a GHG reduction point of view, utilization of straw in biogas plants is very attractive, because DM not digested in the biogas plant adds to the build up of carbon in arable land when contained in and spread with the digested manure.