Epuramat: Digestate and biogas plants

Biogas plants have become a very important source for generating renewable energy. Until now, the biggest problem with biogas plants has been the unsolved issue of how to recycle digestate. Digestate is normally spread on fields as fertilizer. However, as this can only be done during the growing season, the digestate has to be stored over the intervening winter. Huge storage tanks have to be built for the interim storage of the fluid digestate. There must also be sufficient space available to accommodate spreading of the end substrate. A large number of biogas plants could be greatly enlarged and made to perform better. There is no shortage of biological material, but, in many instances, there simply isn’t the space to re-use it (over-fertilization).

Epuramat technology makes it possible remove the water from digestate, dry it and process it into pellets, which are easy to store. When the growing season comes, the pellets are ground up by agricultural machinery and put on the fields as fertilizer by a spreader. Any pellets that are surplus to requirements or produced outside the growing season are very good for producing heat, due to their high thermal value. This can be used to supply power to the public network, and to produce heat to dry the wet pellets and feed the distribution network.

Ultra-filtration membrane biology is used downstream to produce water for industrial use. This helps to preserve natural water sources and delivers costs savings in terms of fresh and wastewater charges. The digestate is thickened with a special pressure-controlled mandrel thickener from a dry mass content of 7% to 40%. The expelled water is then separated from solid matter in the ExSep and processed into industrial and mixing water by ultra-filtration. The separated solids are then taken away again to be used for sludge thickening.