Moderate pretreatment: a practical approach for bioconversion of cellulosic biomass

When pretreating biomass under harsh conditions (extreme pHs and high temperatures), biomass chemical components will degrade into by-products that become inhibitors for the subsequent processing. However, moderate pretreatment can be developed to avoid sugar degradation and toxic compounds formation during pretreatment. As a result, a whole slurry process without inter-stage washing/detoxification can be used, which can significantly reduce capital/operational cost. A moderate pretreatment must remove some lignin but do not break down lignin to simple compounds.It should achieve some defibrillization without much sugar degradation. In a word, It is enough as long as cell wall pores/channels are opened. "Over pretreatment" may improve cellulose accessibility but inevitably cause other chemical components degradation. The right degree of pretreatment is the key. 

The solution to 7 Billion Consuming Resources

On 11/01/2011, the world population hit 7 billion, a warning to the world’s resources: limited food, absolute water scarcity, increasing consumption of non-renewable oil.


One solution: technological advancements and a free market.

• Desalination: to get fresh water from the sea!
• Hybrid and high yield food: Transgenic plants?
• Alternative energy- biofuels,natural power sources like solar and wind may be an alliterative before our fossil fuels run out.

Biomass particle size

It is agreed that biomass feedstock particle sizing can impact the economics of cellulosic ethanol commercialization through its effects on conversion yield and energy cost. Physical size reduction can not always achieve expected effect of biomass enzyme digestibility. For example, the thickness of woody biomass play more critical role in chemical pretreatment of wood chips than its length. Defibrillation of grass biomass is more efficient than size reduction in terms of enzymatic hydrolysis.

Therefore, for practical application, an appropriate size reduction needs to be selected based on the biomass type,what chemicals to be used for pretreatment. The smaller does not mean the best!