A process for converting lignocellulosic biomass to fuel, wherein lignocellulosic feedstock is soaked in a sulfuric acid solution to demineralize the feedstock, the demineralized feedstock is pretreated at a temperature between 150° C. and 230° C. and a pH between 1 and 2.5, at least part of the pretreated material is converted to a fermentation production such as ethanol, and at least a portion of a secondary stream, such as still bottoms from the distillation of ethanol, is converted to biogas by anaerobic digestion. Soaking the lignocellulosic feedstock in sulfuric acid solution reduces the amount of sulfuric acid required for the pretreatment, and thus the amount of sulfate carried downstream to the anaerobic digestion. This increases the biogas yield and/or xylose yield. A recycling process, wherein mineralized soaking liquid produced in the soaking process is fed to cation exchange to remove minerals, reduces excess waste of the sulfuric acid and water usage.

Disclosed herein are methods, systems, and compositions for the uniform pretreatment of biomass within seconds with low inhibitor formation. The pretreatment process is used to convert biomass to a fuel, sugars, or other useful chemicals by subjecting the feedstock to a rapid retention time under pressure and temperature and/or chemical reactant. The system includes at least one high pressure, steam impermiable plug and a continuously-operating valve discharge apparatus to discharge pretreated feedstock while maintaining uniform pressure on the pretreatment system.

A method for treating biomass including lignocellulosic polymers. The biomass is treated in a mixture of water with at least one oxidizing agent and steam at a temperature in a range of from about 130° C. to about 220° C. for a period from about 5 seconds to about 10 hours. The pH of the mixture is periodically measured for substantially an entire duration of the treating step. As necessary, based on the measured pH of the mixture, adjusting the pH of the mixture into a range of from about pH 4.5 to about pH 7.5 by adding a base to the mixture.

An integrated process and corresponding apparatus that produces a relatively clean, delignified cellulose product from lignocellulosic biomass. The method includes treating a portion of the delignified cellulose itself as a substrate to produce on-site cellulolytic enzymes, including further treating the remaining delignified cellulose with the resulting cellulolytic enzymes for in situ enzymatic hydrolysis. The process and apparatus are useful to produce fermentable sugars for cost-effective manufacturing of fermentable sugars, fuels, bioproducts and chemicals.

Methods of fractionating lignocellulosic biomass using maleic acids are provided. Also provided are methods of forming lignin particles, furans, sugars, and/or lignocellulosic micro- and nanofibrils from the liquid and solid fractions produced by fractionation process. The fractionation can be carried out at low temperatures with short reaction times to carboxylate and dissolve lignin with a low degree of condensation.

Moisturized organic material is treated by communicating with a vacuum pump (44) to selectively reduce pressure within a vessel (12) below atmospheric pressure and to a vaporization point, such as at 30 to 17.8° C., for a period of time sufficient to create an internal pressure to rupture cell walls. While being subjected to vacuum below atmospheric pressure, the vessel (12) is rotated to homogenize the moisturized organic material. The organic material can be moisturized by non-potable water including moisture collected by a moisture collector (44b) in the conduit (44a) between the vessel (12) and the vacuum pump (44) and by chilled feed water acting as the seal fluid in the vacuum pump and heated while flowing through a heat exchanger (148) of the moisture collector (44b). Heat can be added by a heater (46) to raise the temperature of low ambient temperature moisturized organic material.

Cotton-containing textiles, such as “trash” feedstock in terms of end-of-life-cotton textiles, may be used to produce sugar without the same kinds of harsh pretreatments used for other biomasses, such as corn, grass sources, or wood. Disclosed is a process for production of sugar from a cotton-containing textile waste fabric comprising optionally mechanically pretreating the cotton-containing textile, pretreating the cotton-containing textile with an acid pretreatment to form a slurry, cooling the slurry, adding at least one base to the slurry, adding at least one additional acid to the slurry to form a buffer in situ, adding a hydrolysis enzyme, and optionally filtering the slurry.

A low-cost process is provided to render lignocellulosic biomass accessible to cellulase enzymes, to produce fermentable sugars. Some variations provide a process to produce ethanol from lignocellulosic biomass (such as sugarcane bagasse or corn stover), comprising introducing a lignocellulosic biomass feedstock to a single-stage digestor; exposing the feedstock to a reaction solution comprising steam or liquid hot water within the digestor, to solubilize the hemicellulose in a liquid phase and to provide a cellulose-rich solid phase; refining the cellulose-rich solid phase, together with the liquid phase, in a mechanical refiner, thereby providing a mixture of refined cellulose-rich solids and the liquid phase; enzymatically hydrolyzing the mixture in a hydrolysis reactor with cellulase enzymes, to generate fermentable sugars; and fermenting the fermentable sugars to produce ethanol. Many alternative process configurations are described. The disclosed processes may be employed for other fermentation products.

Provided herein are compositions and processes concerning efficient downstream processing of products derived from organic acids pretreatment of plant materials.

A method for pretreating lignocellulosic biomass to improve fermentability is disclosed. The method involves reacting lignocellulosic biomass with an acidic mixture while heating at a temperature from about 120° C. to about 200° C. to produce a prehydrolysate mixture. The acidic mixture includes a dilute acid and nucleophilic proteins, hydrolyzed amino acids or combinations thereof.