Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production

Abstract

Results from an investigation of the mechanical size reduction with the Szego Mill™ as a pretreatment method for lignocellulosic biomass are presented. Pretreatment is a highly expensive and energy-consuming step in lignocellulosic biomass processing. Therefore, it is vital to study and optimize different pretreatment methods to find a most efficient production process. The biomass was milled with the Szego Mill™ using three different approaches: dry milling, wet milling and for the first time nitrogen assisted wet milling was tested. Bioethanol and biogas production were studied, but also fibre analysis and SEM (scanning electron microscope) analysis were carried out to characterize the effect of different milling approaches. In addition, two different process flows were used to evaluate the efficiency of downstream processing steps. The results show that pretreatment of barely straw with the Szego Mill™ enabled obtaining glucose concentrations of up to 7 g L−1 in the hydrolysis mixture, which yields at hydrolysis efficiency of 18%. The final ethanol concentrations from 3.4 to 6.7 g L−1 were obtained. The lowest glucose and ethanol concentrations were measured when the biomass was dry milled, the highest when nitrogen assisted wet milling was used. Milling also resulted in an 6–11% of increase in methane production rate during anaerobic digestion of straw.

Effect of Ink and Pretreatment Conditions on Bioethanol and Biomethane Yields from Waste Banknote Paper

“…Distilled water was added to the flasks to obtain a total working volume of 200 mL. The hydrolysis took place for 72 h, at a temperature of 50 °C, under constant stirring in the orbital shaker (IKA ® -Werke GmbH & Co. KG, Staufen im Breisgau, Germany) [ 18 ]. After the hydrolysis, the solid and liquid fractions of the samples were separated by centrifugation (Thermo Scientific Heraeus megacentrifuge, Waltham, USA) at 10,000 rpm for 30 min.…”

“…Although chemical pretreatment methods have been widely used and are effective in dissolving lignin and hemicellulose, they are still expensive because of the high cost of chemicals [ 17 ]. Besides, several inhibitors, such as aliphatic carboxylic acids, phenolic compounds, and furans, are formed during chemical pretreatment, which may disrupt subsequent hydrolysis and fermentation processes [ 18 , 19 ]. Physical pretreatment methods include comminuting, irradiation, and freezing, while biological pretreatment methods use fungi, enzymes, or microorganisms to break down the lignin and hemicellulose bonds [ 14 , 16 ].…”

Energy-Efficient Advanced Ultrafine Grinding of Particles Using Stirred Mills—A Review

“…Hammar Mill Corn stover and wheat straw grinding [136] 7 Roller Mill Pig Feed [137] and cement grinding [138] Table 6. Different types of stirred mills, their specifications, and their energy requirements in past years.…”

Mechanical pretreatment of lignocellulosic biomass toward enzymatic/fermentative valorization

“…Inside the case are more than one screw-like cylinders that rotate around its axis and the axis of the cage. Raud et al. (2020) used this technology to pretreat barley straw with three different approaches: dry, wet, and liquid nitrogen assisted.…”

“…Dry milling obtained the highest BMP (from 269 to 292 L CH 4 /kg raw material). However, the highest production rate was obtained with liquid nitrogen assisted ( Raud et al., 2020 ). The lowest particle size obtained from the bibliography was 17.25 μm ( Bai et al., 2020 ).…”