Archive for Lignocellulosic pretreatment

Effect of Steam Explosion on Biomass

Before enzymes can efficiently hydrolyse the sugar components of biomass, biomass needs to be pre-treated to expose these sugars to enzymatic attack. Why is this necessary? Well the highly complex lignocellulosic matrix consisting of Cellulose, hemicellulose and lignin forms a barrier against enzymes which prevents degradation of the biomass into its individual components.

Steam explosion is one man-made way in overcoming this barrier, or in other words overcome the recalcitrant propery of biomass that is observed in nature. By subjecting biomass to high pressure steam for a certain period of time and then explosively depressurizing the biomass through release of steam/biomass one can break apart the lignocellulosic structure effectively yielding a highly digestible substrate.

Compare the following pictures of raw un-pretreated triticale straw with that that has been steam exploded at a steam temperature of around 200 degrees and a residence time of 5 – 10 minutes. One can visually see how the biomass has been fragmented and destroyed by this pretreatment technology.

Raw straw for steam explosion

Raw unpretreated triticale straw

Pretreated biomass

Steam Exploded triticale straw

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Steam Gun Arrival

Steamgun? What is that? This is a piece of equipment that is used in preatreatment of biomass so that Bio-ethanol can be produced. We have one arriving here early next week which is to be incorparated into our lignocellulosic research facilites.

So how does it work and what is its purpose? Let me start with its purpose. As I’ve mentioned it is used in pretreatment which in short opens up the biomass structure to¬† enzymatic attcack. Once pretreated, enzymes are able to efficiently attack the structure of the biomass and convert it into fermentable sugars. The fermentable sugars can then be fermented into bio-ethanol. Without pretreatment the structure of the biomass is basically inpenetrable and immune to enzymatic attack which results in extremely low ethanol yields.

So how does the steamgun pretreat the biomass material? It achieves this by placing the biomass under high pressure and temperature through steam addition to the material for a certain period of time. At the end of the pretreatment the pressure is suddenly released which cause the material to explode making it more accessible to enzymatic attack. This is in short how the steamgun works but I will have to explain it a bit more in detail the effect and advantages of pretreatment technologies. Hopefully soon I will upload pictures of our new steamgun.

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