Mineral elements present in lignocellulosic biomass feedstocks may accumulate in biorefinery process streams, where they can cause technological problems and contaminate end-products. Silicon can particularly be problematic due to its high abundance in some lignocellulosic biomasses [1]. A better understanding of the distribution of mineral elements in various fractions in response to pretreatment parameters is therefore important in relation to development of new biorefinery processes.
In this work, mineral composition in solid fractions of wheat straw biomass after pretreatment at 1 kg-scale was modelled using an empirical factor, denoted cpH, in an extended severity equation, Eq. 1.
, (1)
cpH describes pH sensitivity of the given
mineral elements. For some elements (e.g. Ca, Mg, P, K), increasing 
, i.e. higher temperature, longer holding
times, and/or higher pH, resulted in lower contents in the solid product. Others
(e.g. Si) did not show any dependency on pretreatment parameters and therefore did
not follow Eq. 1.
Figure 1: Content of selected mineral elements vs. pretreatment severity calculated by the extended severity equation. Adapted from [2]
This study showed that for some mineral elements, the amount ending up in the solid fraction could be controlled by varying pretreatment parameters. Other mineral elements, such as Si, are an integral part of the biomass, which will remain in the solid insoluble fraction.
References
1. D.M. Le, H.R. Sørensen, N.O. Knudsen, A.S. Meyer, Biofuels Bioprod Bioref 9, (2015) 109.
2. D.M. Le, H.R. Sørensen, N.O. Knudsen, J.K. Schjoerring, A.S. Meyer, Biotech biofuels 7 (2014) 141.