Monday, April 4, 2011

Bioconversions of lignocellulosic biomass: the points we cannot overlook

Pretreatment

• If you pretreat biomass at alkaline conditions, be sure to separate lignin before neutralization. Otherwise, the solublized lignin will be precipitated or re-deposited when pH drops.
• If you pretreat biomass at acidic conditions, be sure the temperature does not exceed 165 C. Otherwise, the lignin will condense and re-distribute through cell wall and become gel coat on the surface of pretreated fiber
• If you pretreat biomass with organosolvents, make sure to recycle/re-use the solvents.


Post-pretreatment
• If run detoxification, make sure the methods to be used with fundamental mechanisms. It is cheap and scalable.
• Recover by-products and easily and economically deal with the chemicals if any.

Enzymatic hydrolysis
• Know what biomass you are using and their sugar composition. Woody and non-woody biomass has different chemical (especially lignin and hemicelluloses) composition.
• Know the pretreatment methods you used. The modification of cell wall structure and chemical composition differ under different thermochemical pretreatments.
• Know what substrate the enzyme cocktail development has been based on. Alkaline and acidic pretreated biomass will end up different cocktail characteristics. The enzyme cocktail may need to be customized in terms of the specific pretreated biomass.


Process
• Avoid or reduce unit operations as much as possible
• Be as simple as possible for process configuration
• Use high solids if possible

Fermentation
• Use cheap nutrients if possible
• Ferment C6 and C5 sugars if possible

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