In this paper it is shown how pretreatment of biomass results in the significant improvement of the biogas yield in the anaerobic digestion (AD) process. The pretreatment is carried out with Lhoist Lime which is a biocompatible material manufactured from high purity calcium oxide originating from natural resources. Apart from AD process improvement, Lhoist Lime has a variety of applications in anaerobic digestion, agriculture and biomass upgrading.
The paper addresses the scientific concepts and practical application of lime pretreatment of biomass. It is shown that during the pretreatment easy digestible carbohydrates are formed and the enzymatic accessibility of the cellulose is increased.
With a series of test using grass biomass, it is be demonstrated that after Lhoist Lime pretreatment, the resulting biomass shows significant improvement of the enzymatic digestibility and methane yield. It was found that the methane production of the AD process increased with 25% which contributes directly to the bottom line. In addition the pretreatment improves the operation of the anaerobic digester because the viscosity of the biomass is lower, the grass material is less prone to agglomeration and the throughput can be increased.
Keywords: Lime, alkali, biomass, pretreatment, enzymatic, digestibility, accessibility, methane, biogas, anaerobic digestion, lignocellulosic, biomass, cellulose, hemicellulose
Biogas is a renewable energy carrier generated via the anaerobic digestion (AD) of biomass. Biogas is rapidly growing in Europe and contributes to our energy independence, reduction of CO2 emissions, and sustainable energy generation. The feedstock for AD units ideally consists of waste streams but in practice animal feeds (e.g. corn) are commonly used. The use of agricultural waste streams such as straw, grass or manure is hampered by their low biogas yield because of the high lignocellulosic composition. In this paper we will show how the application of lime pretreatment using Lhoist Lime can unleash the potential of low cost waste streams and can improve the biogas yield of fibrous biomass.
8 Appleton Court, Calder Park, Wakefield, WF2 7AR, UK
Consultancy and Laboratory services: + 44 (0)1924 242255
Conferences and Training enquiries: +44 (0)1924 257891