The present invention is directed to a process for biologically converting carbohydrates from
lignocellulosic biomass comprising the steps of: suspending
lignocellulosic biomass in a flow-through reactor, passing a reaction solution into the reactor, wherein the solution is absorbed into the
biomass substrate and at least a portion of the solution migrates through said
biomass substrate to a liquid reservoir, recirculating the reaction solution in the liquid reservoir at least once to be absorbed into and migrate through the
biomass substrate again. The biological converting of the may involve hydrolyzing
cellulose,
hemicellulose, or a combination thereof to form oligosaccharides, monomelic sugars, or a combination thereof; fermenting oligosaccharides, monomelic sugars, or a combination thereof to produce
ethanol, or a combination thereof. The process can further comprise removing the reaction solution and
processing the solution to separate the
ethanol produced from non-fermented solids.