Some processes aimed to biofuels production, use lignocellulosic wastes as feedstocks for fermentative conversion. If this is the case, pretreatment is required to make these resources fully digestible. Among a wide range of pretreatment options, this study focuses and compares oxidative-alkaline and biological. The reactions that lead to delignification are discussed and modeled. In addition, other compositional changes during pretreatment are briefly reviewed. The obtained yields are introduced to ASPEN simulations to make an economical assessment of each type of pretreatment within the MixAlco process.
The chosen lignocelluloses feedstock was recycled cardboard commonly used in Colombia to accommodate and transport chicken eggs. This biomass is high in lignin content, with more than 40%.
Oxidative-alkaline pretreatment used a lime loading of 0.5g of Ca(OH)2/g of biomass and 30 mL of 0.5 to 2% peroxide were added per g of biomass. A factorial design of 23 was used varying temperature from 80 to120oC.
Biological pretreatment used Laccase Suberase, an enzyme of Novozymes® at 55oC and a pH of 6.5 according to the best activity coefficient obtained in the operational range of 3 to 7 pH (Baldrian, 2005) . A factorial design of 33 was deployed, varying enzymatic loading, amount of substrate and residence time.
All biomass samples (pretreated and otherwise) were characterized, and the yield of sugars and lignin were obtained for each pretreatment and for the combined pretreatment and enzymatic hydrolysis to recommend pretreatment conditions on the basis of highest yield. All data was then loaded in Aspen Plus ®, in a simulation which reproduce the MixAlco ® process (Gousame, 2011) and gives as result the cost of the whole process including pretreatment.
The final result is the quantitative comparison of chemical and biological lignin degradation if the MixAlco process is used.
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