Knowledge Base

Solid feedstock is organic input material with a high dry matter content that is fed into an anaerobic digester in solid or semi-solid form, rather than as a pumpable liquid. Examples include maize silage, straw, grass, solid manure, and other fibrous or bulky biomass. Solid feedstock requires dedicated feeding, mixing, and dosing equipment to feed it into the digester alongside or instead of liquid feedstocks.

What is solid feedstock?

Solid feedstock is organic material fed into a biogas digester in a solid or semi-solid state, typically with a higher dry matter content than liquid feedstocks such as manure or process water. Common examples include maize silage, rye silage, grass, straw, and solid manure, such as chicken manure. Because these materials do not flow or pump like liquids, they require dedicated equipment such as the HoSt Mixing / Dosing Feeder® or HoSt Moving Floor Feeder® to dose them accurately into the digester, sometimes combined with the HoSt Biomix Feeder® to pre-mix solid biomass with liquid digestate into a homogeneous, pumpable input. Once inside the digester, solid feedstocks such as grass and straw can float and form drifting layers, so HoSt applies paddle mixers like the HoSt GiantMix® to keep the material in suspension, prevent foaming, and support a higher dry matter content within the tank, allowing more low-value solid products to be used alongside or instead of maize silage.