Flow-through biological conversion of lignocellulosic biomass

A process for biologically converting carbohydrates from lignocellulosic biomass, comprising the steps of:

• suspending lignocellulosic biomass in a flow-through reactor, wherein said reactor comprises:
• a reactor vessel having a fluid inlet and a fluid outlet;
• a reservoir tank having a fluid inlet and a fluid outlet, wherein said fluid outlet of said reservoir tank is fluidly connected to said fluid inlet of said reactor vessel;
• and
• a fluid passageway, wherein one end of said passageway is connected to said fluid outlet of said reactor vessel and another end of said passageway is connected to said fluid inlet of said reservoir tank;
• passing a reaction solution into said reactor, wherein said reaction solution is absorbed into said biomass and at least a portion of said reaction solution migrates through said biomass substrate to a liquid reservoir in said reactor vessel;
• and
• recirculating said reaction solution in said liquid reservoir at least once, wherein said reaction solution flows from said fluid outlet of said reactor vessel through said passageway to said reservoir tank and then into said fluid inlet of said reactor vessel;
• whereby a portion of carbohydrates in said lignocellulosic biomass are biologically converted,
• wherein said biological conversion comprises fermenting oligosaccharides, monomeric sugars, or a combination thereof to produce a fermentation product,
• and wherein said recirculation of said solution is driven by a build-up of fermentation gases in said flow-through reactor.