1. Mikrobiell förbehandling Guido Zacchi, LTH

2. Develop and optimise pretreatment of lignocellulosic agricultural raw materials and rest products 1.Pre-pretreatment to facilitate storage and to facilitate the pretreatment 2.Perform pretreatment at milder conditions with a high yield of carbohydrates and minimal degradation of sugars 3.Improve the production of biogas from the stillage after SSF of pretreated material Overall aim Should result in better utilisation of the agricultural residues i.e with higher energy efficiency and lower production cost

3. The influence of impregnation with lactic acid on sugar yields from steam pretreatment Organic acids (Lactic acid) :  Weak acids (Less corrosive, lower degree of neutralization)  Biodegradable to produce biogas  Ensilage (crop preservation method)

4. WWT Fermentation Biomass Pretreatment Enzymatic Hydrolysis Distillation Sep CHP Biogas Lignin Stillage SSF Yeast cultivation Dehydration Ethanol Heat & Power AD Sludge Liquid Pretreatment influences all other process steps! Schematic process

5. Pretreatment conditions OM-SOM+STM-STM+SRefRef.L Storage with lactic acid (months) 1122-- Concentration of. Lactic acid (wt%) 0.5 0 Impregnation with SO2 (wt%) 02.50 0 Temperature (C)210200210200 210 Residence time (min)555555 Pretreatment conditions

6. The influence of impregnation with lactic acid on sugar yields from steam pretreatment Sugarcane bagasse Sugar yield (% of theoretical in the raw material) OM: One month storage with Lac TM: Two months storage with Lac Ref.: Impregnation with SO 2 only Ref.L: Impregnation with Lac only -S: Only storage with Lac +S: Storage with Lac and impregnation with SO 2

7. Sugar degradation products (g/100 g raw material) Concentration (g/100 g raw material) OM-S OM+S TM-S TM+S Ref. Ref.L

8. Straw Pretreatment SSF Distillation Sep Biogas Solid Stillage Ethanol AD Liquid Slurry Straw Pretreatment SSF Distillation Sep Biogas Solid Stillage Ethanol AD Liquid Scenario 1 Scenario 2 Steam pretreatment of wheat straw The influence of impregnation with acetic acid

9. Steam pretreatment of wheat straw The influence of impregnation with acetic acid Acetic acid concentration Energy efficiency (%) Lignin assumed to be used for process heat + electricty

10. Ensiling – for storage Oleskowicz-Popiel et al, Biomass and Bioenergy 35, p2087 (2011) Crops Fresh maize (whole crop) Fresh rye (whole crop) Fresh clover (whole crop) Enzymatic hydrolysis and SSF tested for Fresh material Ensiled material Pretreated ensiled material (190 C, 10 min at 6% DM)

11. Ensiling – for storage (2) Enzymatic Hydrolysis Yield (g glucose per 100 gram cellulose)

12. MaizeRyeClover Fresh material29.939.041.8 Ensiled material29.028.134.5 Ensiled + pretreated material72.080.775.7 Ensiling – for storage (3) SSF (with S.cerevisae) Overall ethanol yield % of theoretical based on available C6 sugars in raw material OBS The materials contain also some starch! Some of the sugars are converted to acids during ensiling

13.  The use of an organic acid (or silage) for storage has improved the pretreatment.  Biogas production after pretreatment with an organic acid works well (data not shown).  Next step is to consider also pentose fermentation as an option and investigate more crops/residues  Perform real ensilage on selected residues Conclusions

14. Acknowledgements Swedish Energy Agency PhD students: Sanam Monavari, Elisabeth Joelsson and Pia-Maria Bondesson